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Fine-Tuning LLaMA for Multi-Stage Text Retrieval: Conclusion, Acknowledgements and References

This paper is available on arxiv under CC 4.0 license.
Authors:
(1) HARRISON WINCH, Department of Astronomy & Astrophysics, University of Toronto and Dunlap Institute for Astronomy and Astrophysics, University of Toronto;
(2) RENEE´ HLOZEK, Department of Astronomy & Astrophysics, University of Toronto and Dunlap Institute for Astronomy and Astrophysics, University of Toronto;
(3) DAVID J. E. MARSH, Theoretical Particle Physics and Cosmology, King’s College London;
(4) DANIEL GRIN, Haverford College;
(5) KEIR K. ROGERS, Dunlap Institute for Astronomy and Astrophysics, University of Toronto. Table of Links Abstract and Intro
Methods
Phenomenology
Discussion and Future Work
Conclusion
Acknowledgments and References 2. METHODS In order to model the behavior of extreme axions, we modified axionCAMB to include an arbitrary field potential shape (in our case, a cosine of the form given in Equation 1), and reconfigured the code to sample the extreme starting angles necessary to probe these potentials. We also modified the effective sound speed of the axions after the onset of oscillations to reflect the growth in structure resulting from the tachyonic field dynamics. Lastly, we implemented a computationally-efficient ‘lookup table’ of the axion background fluid evolution in order to speed up the computation of the perturbation equations of motion. The details of implementing extreme axions into axionCAMB are presented below [2]. 2.1. Review of axionCAMB The numerical treatment of axions in axionCAMB is described in detail in Hlozek et al. ˇ (2015), but we review the dynamics of axions here in a potential-agnostic way in order to set up our discussion of modeling extreme axions. In theory, the best way of modeling the dynamics of axion dark matter is to model the behaviour of the field throughout all of cosmic history, and derive all cosmological parameters from those primary variables. However, since this field evolution includes periods of extremely rapid oscillations at late times, simulating this is computationally prohibitive and numerically unstable. Instead, the axion field is modeled directly at early times, but the code switches to a simplified fluid approximation at late times (Hlozek et al. ˇ 2015). This piecewise background evolution could then be called when solving the equations of motion for the fluid perturbations (axion density perturbation δa and axion heat flux u), allowing for efficient and stable computation of the final axion power spectrum. This method is discussed here, building on the discussion in Hu (1998) and Hlozek et al. ˇ (2015). axionCAMB runs through this early pre-oscillatory phase several times in order to determine the proper initial value of the axion field required to produce the desired final axion density, and the time at which it can safely switch back to the free particle CDM solution at late times. It then dynamically evolves these initial conditions (integrating the equation of motion for a field using a Runge-Kutta integrator, Runge 1895) until the field starts to oscillate, at which point it switches over to the known free-particle solution for DM evolution (Hlozek et al. ˇ 2015). This results in a new set of equations of motion for the axion perturbations after the onset of oscillations: The perturbation equations of motion in these two regimes can be used to calculate the evolution of the axion perturbations, and make predictions for cosmological observables such as the MPS or CMB. 2.2. Finely tuned initial conditions Restructuring the initial shooting methods to specify the field starting angle allows us to probe the effects of extreme starting angles in new ways. We can specify starting angles arbitrarily close to π, in order to see the effects of these extremely finely tuned angles on other observables. In addition, when performing MCMC analysis, having the starting angle as a free parameter allows us to impose arbitrary priors on this starting angle. We can use these priors to test the dependence of any constraints on the level of fine tuning of the axion starting angle. 2.3. Modeling the early-oscillatory effective axion sound speed To get a sense of the effects of the anharmonic potential on the axion fluid sound speed, we first solve the axion field perturbation equations of motion, This approximation of the fluid sound speed is shown in red in the lower subplot of Figure 2. In order to approximate the boost in the axion sound speed shown in the field equations without changing the late-time evolution of the perturbations, we modified the vanilla axion fluid sound speed to include a large negative spike just after the onset of oscillations. This negative triangular spike is shown in green in the lower subplot of Figure 2. The width and height of this spike were fit to match the approximate sound speed computed from the field perturbation solution. The width (C1) was fit to the delay in scale factor a between the onset of axion oscillations and the asymptotic sign change in the field solution sound speed. This numerical width was then approximated as a power law function of the scale factor k of the perturbation, depends linearly on the scale factor at the onset of oscillations, which in turn depends on the axion mass, fraction, and starting angle, The power spectrum results for this method can be compared to the literature, where other groups have used the exact field perturbation equations of motion to compute the matter power spectrum for extreme axions, such as Leong et al. (2019). In Figure 3 we can see the comparison in the matter power spectrum for both a vanilla axion and an extreme axion with a starting angle deviating from π by 0.2 degrees, and we find that they are in remarkably close agreement with Leong et al. (2019). However, this close agreement seems to hold best at z = 0, when these power spectra are computed, while the higher redshifts comparison may be more nuanced. Figure 2 suggests that while the exact field solution and the new approximate fluid solution agree at very late times, their evolution at early times are not fully equivalent, so more work may need to be done on this approximation in order to perform comparisons to high-redshift observables. 2.4. Using lookup tables for efficient modeling of field Extending the full field evolution so much later past the onset of oscillations requires far more computational resources than ending the field evolution as soon as oscillations begin. Greater numerical resolution, in both time and possible field potential scale, is also required to integrate these rapidly oscillating variables. With these increases to computational time, the new version of axionCAMB takes around seventy seconds to complete. While this may be feasible when computing a single power spectrum result, this is computationally intensive with which to run an MCMC analysis, which may require tens to hundreds of thousands of separate calls to axionCAMB. 2.5. Summary of changes to axionCAMB In order to model axions with extreme starting angles in a cosine field potential using the computationally efficient field formalism used in axionCAMB, we have introduced a number of modifications to axionCAMB which are explained above, but summarized here. • We replaced the quadratic approximation of the field potential with an arbitrary potential function, currently set to the canonical cosine potential. • We modified the effective axion fluid sound speed to reproduce the growth in structure seen in the exact field perturbation equations of motion. • We precomputed a lookup table for the axion background evolution which significantly reduced the runtime. The result is an accurate modeling of extreme axion background and perturbation evolution for an arbitrary axion mass, density, and starting angle that only takes ∼ 7 seconds to run. This powerful tool can shed new light on the behaviour and detectability of these extreme axion models, as discussed below. 2.6. Data: Ly-α forest estimates of the MPS [2] axionCAMB is in turn based on the cosmological Boltzmann code, CAMB (Lewis & Bridle 2002). [4] A logarithmic dependence for the background field can be derived analytically for the anharmonic corrections to the relic density (Lyth 1992). This paper is available on arxiv under CC 4.0 license. Authors: (1) HARRISON WINCH, Department of Astronomy & Astrophysics, University of Toronto and Dunlap Institute for Astronomy and Astrophysics, University of Toronto; (2) RENEE´ HLOZEK, Department of Astronomy & Astrophysics, University of Toronto and Dunlap Institute for Astronomy and Astrophysics, University of Toronto; (3) DAVID J. E. MARSH, Theoretical Particle Physics and Cosmology, King’s College London; (4) DANIEL GRIN, Haverford College; (5) KEIR K. ROGERS, Dunlap Institute for Astronomy and Astrophysics, University of Toronto. This paper is available on arxiv under CC 4.0 license. Authors: Authors: (1) HARRISON WINCH, Department of Astronomy & Astrophysics, University of Toronto and Dunlap Institute for Astronomy and Astrophysics, University of Toronto; (2) RENEE´ HLOZEK, Department of Astronomy & Astrophysics, University of Toronto and Dunlap Institute for Astronomy and Astrophysics, University of Toronto; (3) DAVID J. E. MARSH, Theoretical Particle Physics and Cosmology, King’s College London; (4) DANIEL GRIN, Haverford College; (5) KEIR K. ROGERS, Dunlap Institute for Astronomy and Astrophysics, University of Toronto. Table of Links Abstract and Intro Methods Phenomenology Discussion and Future Work Conclusion Acknowledgments and References Abstract and Intro Abstract and Intro Methods Methods Phenomenology Phenomenology Discussion and Future Work Discussion and Future Work Conclusion Conclusion Acknowledgments and References Acknowledgments and References 2. METHODS In order to model the behavior of extreme axions, we modified axionCAMB to include an arbitrary field potential shape (in our case, a cosine of the form given in Equation 1), and reconfigured the code to sample the extreme starting angles necessary to probe these potentials. We also modified the effective sound speed of the axions after the onset of oscillations to reflect the growth in structure resulting from the tachyonic field dynamics. Lastly, we implemented a computationally-efficient ‘lookup table’ of the axion background fluid evolution in order to speed up the computation of the perturbation equations of motion. The details of implementing extreme axions into axionCAMB are presented below [2]. 2.1. Review of axionCAMB The numerical treatment of axions in axionCAMB is described in detail in Hlozek et al. ˇ (2015), but we review the dynamics of axions here in a potential-agnostic way in order to set up our discussion of modeling extreme axions. In theory, the best way of modeling the dynamics of axion dark matter is to model the behaviour of the field throughout all of cosmic history, and derive all cosmological parameters from those primary variables. However, since this field evolution includes periods of extremely rapid oscillations at late times, simulating this is computationally prohibitive and numerically unstable. Instead, the axion field is modeled directly at early times, but the code switches to a simplified fluid approximation at late times (Hlozek et al. ˇ 2015). This piecewise background evolution could then be called when solving the equations of motion for the fluid perturbations (axion density perturbation δa and axion heat flux u), allowing for efficient and stable computation of the final axion power spectrum. This method is discussed here, building on the discussion in Hu (1998) and Hlozek et al. ˇ (2015). axionCAMB runs through this early pre-oscillatory phase several times in order to determine the proper initial value of the axion field required to produce the desired final axion density, and the time at which it can safely switch back to the free particle CDM solution at late times. It then dynamically evolves these initial conditions (integrating the equation of motion for a field using a Runge-Kutta integrator, Runge 1895) until the field starts to oscillate, at which point it switches over to the known free-particle solution for DM evolution (Hlozek et al. ˇ 2015). This results in a new set of equations of motion for the axion perturbations after the onset of oscillations: The perturbation equations of motion in these two regimes can be used to calculate the evolution of the axion perturbations, and make predictions for cosmological observables such as the MPS or CMB. 2.2. Finely tuned initial conditions Restructuring the initial shooting methods to specify the field starting angle allows us to probe the effects of extreme starting angles in new ways. We can specify starting angles arbitrarily close to π, in order to see the effects of these extremely finely tuned angles on other observables. In addition, when performing MCMC analysis, having the starting angle as a free parameter allows us to impose arbitrary priors on this starting angle. We can use these priors to test the dependence of any constraints on the level of fine tuning of the axion starting angle. 2.3. Modeling the early-oscillatory effective axion sound speed To get a sense of the effects of the anharmonic potential on the axion fluid sound speed, we first solve the axion field perturbation equations of motion, This approximation of the fluid sound speed is shown in red in the lower subplot of Figure 2. In order to approximate the boost in the axion sound speed shown in the field equations without changing the late-time evolution of the perturbations, we modified the vanilla axion fluid sound speed to include a large negative spike just after the onset of oscillations. This negative triangular spike is shown in green in the lower subplot of Figure 2. The width and height of this spike were fit to match the approximate sound speed computed from the field perturbation solution. The width (C1) was fit to the delay in scale factor a between the onset of axion oscillations and the asymptotic sign change in the field solution sound speed. This numerical width was then approximated as a power law function of the scale factor k of the perturbation, depends linearly on the scale factor at the onset of oscillations, which in turn depends on the axion mass, fraction, and starting angle, The power spectrum results for this method can be compared to the literature, where other groups have used the exact field perturbation equations of motion to compute the matter power spectrum for extreme axions, such as Leong et al. (2019). In Figure 3 we can see the comparison in the matter power spectrum for both a vanilla axion and an extreme axion with a starting angle deviating from π by 0.2 degrees, and we find that they are in remarkably close agreement with Leong et al. (2019). However, this close agreement seems to hold best at z = 0, when these power spectra are computed, while the higher redshifts comparison may be more nuanced. Figure 2 suggests that while the exact field solution and the new approximate fluid solution agree at very late times, their evolution at early times are not fully equivalent, so more work may need to be done on this approximation in order to perform comparisons to high-redshift observables. 2.4. Using lookup tables for efficient modeling of field Extending the full field evolution so much later past the onset of oscillations requires far more computational resources than ending the field evolution as soon as oscillations begin. Greater numerical resolution, in both time and possible field potential scale, is also required to integrate these rapidly oscillating variables. With these increases to computational time, the new version of axionCAMB takes around seventy seconds to complete. While this may be feasible when computing a single power spectrum result, this is computationally intensive with which to run an MCMC analysis, which may require tens to hundreds of thousands of separate calls to axionCAMB. 2.5. Summary of changes to axionCAMB In order to model axions with extreme starting angles in a cosine field potential using the computationally efficient field formalism used in axionCAMB, we have introduced a number of modifications to axionCAMB which are explained above, but summarized here. • We replaced the quadratic approximation of the field potential with an arbitrary potential function, currently set to the canonical cosine potential. • We modified the effective axion fluid sound speed to reproduce the growth in structure seen in the exact field perturbation equations of motion. • We precomputed a lookup table for the axion background evolution which significantly reduced the runtime. The result is an accurate modeling of extreme axion background and perturbation evolution for an arbitrary axion mass, density, and starting angle that only takes ∼ 7 seconds to run. This powerful tool can shed new light on the behaviour and detectability of these extreme axion models, as discussed below. 2.6. Data: Ly-α forest estimates of the MPS [2] axionCAMB is in turn based on the cosmological Boltzmann code, CAMB (Lewis & Bridle 2002). [4] A logarithmic dependence for the background field can be derived analytically for the anharmonic corrections to the relic density (Lyth 1992).

Extreme Axions Unveiled: A Novel Fluid Approach for Cosmological Modeling - Methods

চরম অক্ষরেখা উন্মোচন: মহাজাগতিক মডেলিংয়ের জন্য একটি অভিনব তরল পদ্ধতি - পদ্ধতি

Extreme Axionen enthüllt: Ein neuartiger Fluidansatz für die kosmologische Modellierung - Methoden

Se revelan los axiones extremos: un nuevo enfoque fluido para el modelado cosmológico - Métodos

Extreme Axions dévoilés : une nouvelle approche fluide pour la modélisation cosmologique - Méthodes

चरम एक्सियंस का अनावरण: ब्रह्माण्ड संबंधी मॉडलिंग के लिए एक नवीन द्रव दृष्टिकोण - विधियाँ

極限アクシオンの解明：宇宙論モデリングのための新しい流体アプローチ - 方法

Extreme Axions 공개: 우주론적 모델링을 위한 새로운 유체 접근 방식 - 방법

Extreme Axions revelados: uma nova abordagem de fluidos para modelagem cosmológica - métodos

Представлены экстремальные аксионы: новый жидкостный подход к космологическому моделированию - Методы

Extreme Axions Ortaya Çıktı: Kozmolojik Modelleme için Yeni Bir Akışkan Yaklaşımı - Yöntemler

Ra mắt các Axion cực đoan: Một phương pháp tiếp cận chất lỏng mới cho mô hình vũ trụ - Phương pháp

揭开极端轴子的面纱：一种用于宇宙学建模的新型流体方法 - 方法

Identifying Axion Conversion in Compact Star Magnetospheres With Radio-Wave Polarization Signatures

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Moving forward, search providers should invest in “better together” experiences that utilize copilots plus traditional search, make these joint experiences more seamless for searchers, and add more support for their use in practice, e.g., help people to quickly understand copilot capabilities and potential and/or recommend the best modality for the current task or task stage. This includes experiences where both modalities are offered separately and can be selected by searchers and those where there is unification and the selection happens automatically based on the query and the conversation context. The foundation models that power copilots have other search-related applications, e.g., for generating and applying intent taxonomies [43] or for evaluation [19]. We must retain a continued focus on human-AI cooperation, where searchers stay in control while the degree of system support increases as needed [44], and on AI safety. 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Navigating Complex Search Tasks with AI Copilots: The Undiscovered Country and References

This paper is available on arxiv under CC 4.0 license. Authors: (1) Ayei E. Ibor, Trustworthy Digital Infrastructure for Identity Systems, The Alan Turing Institute, United Kingdom; (2) Mark Hooper, Trustworthy Digital Infrastructure for Identity Systems, The Alan Turing Institute, United Kingdom; (3) Carsten Maple, Trustworthy Digital Infrastructure for Identity Systems, The Alan Turing Institute, United Kingdom; (4) Gregory Epiphaniou, WMG, University of Warwick, United Kingdom. Table of Links Abstract & Introduction Background Review of Literature Methodology Discussion of Findings Conclusion and Future Work & References 6. Conclusion and Future Work Trustworthy interoperability is a key enabler for identity management and widens the dimensions of e-government in developing countries. This research provided insights into the challenges, opportunities, and requirements of interoperability and highlighted the limitations of current interoperability solutions such as the Estonian X-Road and the eIDAS of the European Union. We found that each existing interoperability solution has its benefits and drawbacks, although both are targeted at a common goal. To achieve seamless communication of identification data, we proposed an approach for scoping requirements by first identifying the key processes to identity management in an interoperability context. Furthermore, we addressed the limitations of the current solutions using an architecture that considers the flexibility of identity verification and validation through an interoperable layer that is based on four interacting layers of data representation, semantics, binding, and security and privacy. For future work, an analysis of country-specific use cases for achieving interoperability in the African identity ecosystem will be performed. References African Union, 2020. The Digital Transformation Strategy for Africa (2020-30), Available at https://openresearch-repository.anu.edu.au/bitstream/1885/278587/1/GhaEcon_24.pdf, Accessed 20 May 2023. Alamillo, I., Mouille, S., Rock, A., Soumelidis, N., Tabor, M., Gorniak, S., 2023. Digital identity standards: Analysis of standardisation requirements in support of cybersecurity policy, Available at file:///C:/Users/aIbor/Downloads/Digital_Identity_Standards%20(1).pdf, Accessed 30 July 2023. Aldosary, M. and Alqahtani, N., 2021. A Survey on Federated Identity Management Systems Limitation and Solutions. International Journal of Network Security & Its Applications (IJNSA) Vol, 13. ANSSI, 2023. The EIDAS Regulation, Available at https://www.ssi.gouv.fr/en/regulation/digital-confidence/the-eidas-regulation/, Accessed 09 April 2023. 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Hummer, D. and Rebovich, D.J., 2023. Identity theft and financial loss. In Handbook on Crime and Technology (pp. 38-53). Edward Elgar Publishing. Irvin-Erickson, Y., 2023. How Does Immigration Status and Citizenship Affect Identity Theft Victimization Risk in the US? Insights from the 2018 National Crime Victimization Survey Identity Theft Supplement. Victims & Offenders, pp.1-24. Kaaniche, N., Laurent, M. and Belguith, S., 2020. Privacy enhancing technologies for solving the privacy-personalization paradox: Taxonomy and survey. Journal of Network and Computer Applications, 171, p.102807. Kanagwa, B., Nakatumba-Nabende, J., Mugwanya, R., Kigozi Kahiigi, E. and Ngabirano, S., 2018. Towards an interoperability e-government framework for Uganda. In e-Infrastructure and e-Services for Developing Countries: 9th International Conference, AFRICOMM 2017, Lagos, Nigeria, December 11-12, 2017, Proceedings 9 (pp. 16-28). Springer International Publishing. Kiourtis, A., Giannetsos, T., Menesidou, S.A., Mavrogiorgou, A., Symvoulidis, C., GRAZİANİ, A., KLEFTAKİS, S., MAVROGİORGOS, K., ZAFEİROPOULOS, N., GKOLİAS, C.A. and KYRİAZİS, D., 2023. Identity management standards: A literature review. Computers and Informatics, 3(1), pp.35-46. Krimmer, R., Dedovic, S., Schmidt, C. and Corici, A.A., 2021, August. Developing crossborder e-Governance: Exploring interoperability and cross-border integration. In International Conference on Electronic Participation (pp. 107-124). Cham: Springer International Publishing. Kotzé, P. and Alberts, R., 2017. Towards a Conceptual Model for an e-Government Interoperability Framework for South Africa. In ICEIS (3) (pp. 493-506). Lips, S., Bharosa, N. and Draheim, D., 2020. eIDAS implementation challenges: the case of Estonia and the Netherlands. 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Mocanu, S., Chiriac, A.M., Popa, C., Dobrescu, R. and Saru, D., 2019. Identification and trust techniques compatible with eIDAS regulation. In Security and Privacy in New Computing Environments: Second EAI International Conference, SPNCE 2019, Tianjin, China, April 13– 14, 2019, Proceedings 2 (pp. 656-665). Springer International Publishing. Pöhn, D. and Hommel, W., 2023. Towards an Improved Taxonomy of Attacks Related to Digital Identities and Identity Management Systems. Security and Communication Networks, 2023. Priisalu, J. and Ottis, R., 2017. Personal control of privacy and data: Estonian experience. Health and technology, 7(4), pp.441-451. Saputro, R., Pappel, I., Vainsalu, H., Lips, S. and Draheim, D., 2020, April. Prerequisites for the adoption of the X-Road interoperability and data exchange framework: a comparative study. In 2020 Seventh International Conference on eDemocracy & eGovernment (ICEDEG) (pp. 216-222). IEEE. Schmidt, C. and Krimmer, R., 2022. 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Trustworthy Interoperability and Identity Management Systems: What Comes Next

189 Stories To Learn About Reading Books

Scientific American, Volume XXIV., No. 12, March 18, 1871 by Various, is part of the HackerNoon Books Series. You can jump to any chapter in this book . Official lists of patents here Official lists of patents ISSUED BY THE U. S. PATENT OFFICE. FOR THE WEEK ENDING MARCH 7, 1871. Reported Officially for the Scientific American. SCHEDULE OF PATENT FEES On each Caveat $10 On each Trade-Mark $25 On filing each application for a Patent, (seventeen years) $15 On issuing each original Patent $20 On appeal to Examiners-in-Chief $10 On appeal to Commissioner of Patents $20 On application for Reissue $30 On application for Extension of Patent $50 On granting the Extension $50 On filing a Disclaimer $10 On an application for Design (three and a half years) $10 On an application for Design (seven years) $15 On an application for Design (fourteen years) $30 For Copy of Claim of any Patent issued within 30 years $1 A sketch from the model or drawing, relating to such portion of a machine as the Claim covers, from upward, but usually at the price above-named. $1 The full Specification of any patent issued since Nov. 20, 1866 at which time the Patent Office commenced printing them $1.25 Official Copies of Drawings of any patent issued since 1836, we can supply at a reasonable cost, the price depending upon the amount of labor involved and the number of views. Full information, as to price of drawings, in each case, may be had by addressing MUNN & CO., Patent Solicitors, 37 Park Row, New York. 112,309.—Hose Sprinkler.—William Anderson, San Francisco, Cal. 112,310.—Locomotive Spark Arrester.—J. G. Armstrong, New Brunswick, N. J. 112,311.—Tool for Carriage Makers' Use.—George Atkinson, San Francisco, Cal. 112,312.—Potato Probe.—John A. Beal, Waterford, N. Y. 112,313.—Hinge for Carriage Doors.—George W. Beers, Bridgeport, Conn. 112,314.—Stove Leg.—James Birckhead, Jr., Baltimore, Md. 112,315.—Clothes Pin.—Orris A. Bishop, Chicago, Ill. 112,316.—Manufacture of Rochelle Salts and Borax.—V. G. Bloede, Brooklyn, N. Y. 112,317.—Beehive.—Felix Brewer, Waynesville, Mo. 112,318.—Thill Coupling.—Theodore Burr (assignor to Allen Muir and Henry Muir), Battle Creek, Mich. 112,319.—Evaporating Pan for Saccharine Liquids.—F. C. Butler, Bellows Falls, Vt., assignor to himself and James B. Williams, Glastonbury, Conn. 112,320.—Door Securer.—William H. Caldwell, Wheeling, W. Va. 112,321.—Toe-calk Bar.—R. B. Caswell, Springfield, Mass. Antedated March 2, 1871. 112,322.—Glass Flattening Furnace and Leer.—James Clabby, Lenox, Mass. 112,323.—Spring Bed Bottom.—Alex. Cole, Manamuskin, N. J. 112,324.—Water Wheel.—E. E. Coleman, West Cummington, Mass. 112,325.—Toy Horse and Carriage.—John B. Cuzner, Bridgeport, Conn. 112,326.—Mackerel-line Holder.—E. L. Decker, Southport, Me. 112,327.—Sewing Machine.—J. William Dufour, Stratford, Conn. 112,328.—Steam Boiler.—Edwards Evans, North Tonawanda, N. Y. 112,329.—Medical Compound for Cure of Catarrh and Asthma.—Erastus Field, Ostrander, Ohio. 112,330.—Machine for Grinding the Cutters of Mowers, etc.—H. C. Fisk, Wellsville, N. Y. 112,331.—Machine for Making Hooks and Eyes.—Jeremy T. Ford, San Francisco, Cal. 112,332.—Churn.—Thompson Freeman, Westfield, Ill. 112,333.—Attachment for Revolving Mold Boards for Plows.—J. S. Godfrey, Leslie, Mich., assignor to himself and S. M. Loveridge, Pittsburgh, Pa. 112,334.—Grain Cleaner and Fertilizer Sifter.—J. A. Green, Mill Dale, Va. 112,335.—Screw Propulsion.—E. C. Gregg (assignor to A. H. Gregg and C. P. Gregg), Trumansburg, N. Y. 112,336.—Seeding Machine.—P. M. Gundlach, Belleville, Ill. 112,337.—Compound for Kindling Fires.—J. L. Hannum and S. H. Stebbins, Berea, Ohio. 112,338.—Lawn Mower.—Benjamin Harnish, Lancaster, and D. H. Harnish, Pequea, Pa. 112,339.—Composition for Pavements.—C. B. Harris, New York city. Antedated February 25, 1870. 112,340.—Spring for Vehicles.—John R. Hiller, Woodland, Cal. 112,341.—Harvester Rake.—S. T. Holly, (assignor to John P. Manny), Rockford, Ill. 112,342.—Door Clamp.—Henry O. Hooper, Diamond Springs, Cal. 112,343.—Taper Holder.—Thomas W. Houchin, Morrisania, N. Y. 112,344.—Metallic Garter.—Henry A. House, Bridgeport, Conn. 112,345.—Bobbin Winder.—Henry A. House, Bridgeport, Conn. 112,346.—Method of Knitting Stockings, etc.—Henry A. House, Bridgeport, Conn. 112,347.—Apparatus for Evaporating and concentrating Liquids.—John Howarth, Salem, Mass. Antedated March 1, 1871. 112,348.—Apparatus for Evaporating and Concentrating Liquids.—John Howarth, Salem, Mass. Antedated March 1, 1871. 112,349.—Apparatus for Removing Oil from Vegetable and other Matters.—Elias S. Hutchinson, Baltimore, Md. 112,350.—Apparatus and Process for Removing Oil from Grain, Seeds, etc.—Elias S. Hutchinson, Baltimore, Md. 112,351.—Chandelier.—Charles F. Jacobsen, New York city. 112,352.—Culinary Vessel.—Carrie Jessup, New Haven, Conn. 112,353.—Machine for Cutting Leather.—Aberdeen Keith, North Bridgewater, Mass. 112,354.—Attaching Knobs to their Spindles.—John F. Keller and Nathaniel Sehner, Hagerstown, Md. 112,355.—Miter Machine.—T. E. King, Boston, Mass. 112,356.—Take-up for Corset Looms.—Julius Kuttner, New York city. 112,357.—Elevator and Carrier.—T. W. Lackore, Worth, Ill. 112,358.—Apparatus for Burning Hydrocarbon Oils.—James R. Lee, Grass Valley, Cal. 112,359.—Burglar Alarm.—Robert Lee, Cincinnati, Ohio. 112,360.—Telegraph Apparatus.—L. T. Lindsey, Jackson, Tenn. 112,361.—Harvester.—J. P. Manny, Rockford, Ill. 112,362.—Harvester.—J. P. Manny, Rockford, Ill. 112,363.—Harvester Rake.—J. P. Manny, Rockford, Ill. 112,364.—Cheese Curd Sink.—H. C. Markham, Collinsville, N. Y. 112,365.—Mowing Machine.—H. C. Markham and Dewitt C. Markham, Collinsville, N. Y. 112,366.—Propeller.—Alex. J. Marshall, Warrenton, Va. Antedated March 3, 1871. 112,367.—Oiler.—Edward McDuff and E. D. Forrow, Warwick, R. I. 112,368.—Wash Boiler.—John McInnes, Oxford, Pa. 112,369.—Propelling Canal Boats.—H. B. Meech, Fort Edward, N. Y. Antedated February 25, 1871. 112,370.—Water-proof Compound for Coating Cloth Wood, Metals, etc.—Peter E. Minor, Schenectady, N. Y. 112,371.—Cooking Stove.—W. N. Moore, Neenah, Wis. 112,372.—Boring Machine.—J. H. Pardieck (assignor to himself and S. M. Brown), Acton, Ind. 112,373.—Vapor Burner.—R. W. Park, Philadelphia, Pa. 112,374.—Machine for Pointing Blanks for Cultivator Teeth.—John Pedder and George Abel, West Pittsburgh, Pa. 112,375.—Bale Tie.—J. E. Perkins, San Francisco, Cal. 112,376.—Lining Walls with Felt, etc.—James Phillips, Chicago, Ill. 112,377.—Cooking Stove.—Samuel Pierce, Boston, Mass. 112,378.—Tack.—A. A. Porter, New Haven, Conn. Antedated Feb. 25, 1871. 112,379.—Machine for Shaping and Cutting Gear Cutters.—F. A. Pratt (assignor to the Pratt & Whitney Company), Hartford, Conn. 112,380.—Combination Camera and Developing Box.—E. C. Ratzell, Philadelphia, Pa. 112,381.—Punching Machine.—J. C. Rhodes, South Abington, Mass. 112,382.—Washing Machine.—J. W. Ricker, Chelsea, Mass. 112,383.—Curtain Fixture.—Charles Robin. Chester, Conn. 112,384.—Machine for Making Printers' Leads.—Isaac Schoenberg, New York city. 112,385.—Slide Valve for Steam Riveting Machines.—Coleman Sellers (assignor to William Sellers & Co.), Philadelphia, Pa. 112,386.—Machine for Polishing Thread.—Samuel Semple, Sr., John Semple, Samuel Semple, Jr., and R. A. Semple, Mount Holly, N. J. 112,387.—Paint Brush.—F. S. Shearer, Washington, Ill. 112,388.—Bee Hive.—S. A. Short, F. J. Short, J. B. Short, and Jasper Kile, Decatur, Ala. 112,389.—Apparatus for Removing Oil from Vegetable and other Matter.—Thomas Sim, Baltimore, Md. 112,390.—Retort for Producing Bisulphide of Carbon.—Thomas Sim, Baltimore, Md. 112,391.—Utilizing the Silky Down of the Wild Cotton. —M. H. Simpson, Boston, Mass. 112,392.—Pruning Shears.—Frank Smiley, Batavia, N. Y. 112,393.—Water-closet Valve.—A. J. Smith, San Francisco, Cal. 112,394.—Gang Plow.—J. W. Sursa, San Leandro, Cal. 112,395.—Grinding Pan and Amalgamator.—W. H. Thoss, West Point, Cal. 112,396.—Street Lantern.—Augustus Tufts, Malden, Mass. 112,397.—Cooking Stove.—Alvin Warren, Swanton, Ohio. 112,398.—Safety Bridle.—James Weatherhead, San José, Cal. 112,399.—Fire Grate.—George Wellhouse, Akron, Ohio. 112,400.—Hay Knife.—G. F. Weymouth, Dresden, Me. 112,401.—Claw Bar.—Charles Winter, Chillicothe, Ohio. 112,402.—Steam Generator.—J. C. Woodhead, Pittsburgh, Pa. 112,403.—Animal Trap.—W. D. Wrightson, Queenstown England. 112,404.—Brush.—John Ames, Lansingburg, N. Y. 112,405.—Clod Fender.—F. L. Bailey, Freeport, Ind. 112,406.—Ruler.—H. S. Ball, Spartanburg, S. C. 112,407.—Fanning Mill.—Benjamin Barney, Time, Ill. 112,408.—Ice-cutting Machine.—Lafayett Barnum (assignor to himself and A. R. Hale), Bridgeport, Conn. 112,409.—Manufacture of Ice.—T. J. Bigger, Kansas City, Mo. 112,410.—Machine for Heading Bolts and Spikes.—Reinhold Boeklen, Brooklyn, N. Y., assignor to himself and Henry Torstrick New York city. Antedated Feb. 28, 1871. 112,411.—Washing Machine.—Joseph Boswell, L. M. Boswell, Jonathan Palmer, and J. H. James (assignors to themselves and Thomas Starbuck), Wilmington, Ohio. 112,412.—Water Wheel.—E. C. Boyles, New York city. 112,413.—Cotton Press.—R. M. Brooks, Pike county, Ga. 112,414.—Paper-cutting Machine.—Samuel Brown (assignor to himself and C. R. Carver), Philadelphia, Pa. 112,415.—Governor for Direct-acting Engines.—A. S. Cameron, New York city. 112,416.—Governor for Direct-acting Engines.—A. S. Cameron, New York city. 112,417.—Butt Hinge.—J. W. Carleton (assignor to the Union Manufacturing Co.), New Britain, Conn. 112,418.—Machine for Cutting Sheet Metal.—C. R. Choate, East Saginaw, Mich. 112,419.—Bit Brace.—William Cleveland, Lawrence, Mass., assignor to himself and James Swan, Seymour, Conn. 112,420.—Steam Engine Governor.—C. A. Condé, Indianapolis, Ind. 112,421.—Carpet-cleaning Machine.—J. C. Craft (assignor to himself and Antonio Rosello), Baltimore, Md. 112,422.—Steam Regulator for Paper Dryers.—Daniel Crosby, Hampden, Me. 112 423.—Metallic Piston and Valve Rod Packing.—G. M. Cruickshank, Providence, R. I. 112,424.—Grain-thrashing and Separating Machine.—John Culham, Grand Rapids, Mich. Antedated Feb. 25, 1871. 112,425.—Cooking Stove.—David Curtis, Mishawaka, assignor to himself and C. B. Graham, South Bend, Ind. 112,426.—Lightning Rod.—S. D. Cushman, New Lisbon, Ohio. 112,427.—Hose Bridge.—Patrick Daily (assignor to himself and J. J. Kehoe), New York city. 112,428.—Cover for Openings in Sidewalks.—William Dale, New York city. 112,429.—Rotary Pump.—F. O. Deschamps, Philadelphia, Pa. 112,430.—Machine for Cutting Files.—James Dodge, Manchester, England, assignor to David Blake, Spencertown, N. Y. 112,431.—Coupling for Railway Cars.—Henry Dubs and S. G. Goodall-Copestake, Glasgow, Great Britain. 112,432.—Tobacco Pipe.—P. J. Dwyer, Elizabethport, N. J. 112,433.—Basket for House Plants.—Albert P. Eastman, Washington, D. C. 112,434.—Sulky Plow.—Milo A. Elliott, Stratford Hollow, N. H. 112,435.—Stretcher for Paintings.—James Fairman, New York city. 112,436.—Body Lantern Holder.—Samuel C. Fessenden, Stamford, Conn. 112,437.—Stove Leg.—Amon L. Finch, Sing Sing, N. Y. 112,438.—Pump Piston.—John S. Follansbee and George Doolittle (assignors to the Forrester Manufacturing Company), Bridgeport, Conn. 112,439.—Shoe.—Samuel W. Francis (assignor to himself and W. H. Newton), Newport, R. I. 112,440.—Guard-Finger for Harvesters.—George Fyfe and Chester Hard, Ottawa, Ill. 112,441.—Dining Table.—S. R. Gardner (assignor to himself and S. M. Marquette), Independence, Iowa. 112,442.—Step Ladder.—M. Boland Geary, New York City. 112,443.—Oilcloth Printing Machinery.—Ebenezer A. Goodes (assignor to Philadelphia Patent and Novelty Company), Philadelphia, Pa. 112,444.—Tenoning Machine.—Lyman Gould, Norwich, Conn. 112,445.—Printer's Case.—Wm. H. A. Gresham, Atlanta, Ga. 112,446.—Lamp Chimney.—Geo. W. Griswold, Factoryville, Pa. 112,447.—Grain Separator.—Philander Griswold, Hudson, Mich. 112,448.—Clamp for Thill Couplings.—John W. Guider (assignor to himself and John Kiefer), St. Joseph, Mo. 112,449.—Bird Cage.—Gottlob Gunther, New York city. 112,450.—Stop Cock and Valve.—William Haas, New York city. 112,451.—Valve for Steam Engines.—Joseph L. Harley, Baltimore, Md., and Xaver Fendrich, Georgetown, D. C. 112,452.—Metallic Hub.—John H. Harper, Pittsburgh, Pa. 112,453.—Composition for Lubricating Machinery.—E. Q. Henderson (assignor to John C. Burroughs and Richard A. Springs) Charlotte, N. C. 112,454.—Post-hole Digger.—Bryant B. Herrick, Decatur, Mich. 112,455.—Door Check.—Levi S. Hicks (assignor to himself, J. Perrin Johnson, and John Buell), Peoria, Ill. 112,456.—Railway-car Brake.—Luther Hill, Stoneham, and Seth D. Tripp, Lynn, Mass. 112,457.—Truss.—Adam Hinoult, Montgomery, N. Y. 112,458.—Feed Bag for Horses.—Walter A. Hough, South Butler, N. Y. 112,459.—Shade Holder for Lamps—Mark W. House, Cleveland, Ohio. 112,460.—Lamp Chimney.—Mark Wiggins House (assignor to the Cleveland Non-Explosive Lamp Company), Cleveland, Ohio. Antedated March 1, 1871. 112,461.—Horse Hay Rake.—James Howard and E. T. Bousfield, Bedford, England. 112,462.—Tongs for Rolling Barrels.—Mark W. Ingle, Indianapolis, Ind. 112,463.—Pitman.—George W. Jayson, Lodi, Ohio. 112,464.—Paste for Paper Hangings.—John Jones (assignor to himself and Henry A. Smith), New York city. 112,465.—Twine Holder.—Edward M. Judd, New Haven, Ct. 112,466.—Clothes Pin or Clasp.—Amos L. Keeports and William Yount, Littletown, Pa. 112,467.—Putting up Hams.—Samuel Edward Kelly, Philadelphia, Pa. 112,468.—Limn Kiln.—Thomas A. Kirk, Kansas City, Mo. 112,469.—Fastening for Seats for Wagons or Sleighs.—John G. Knapp and John F. Robertson (assignors of one third their right to James H. Holly), Warwick, N. Y. 112,470.—Potato Planter.—George Knowlton (assignor for one-half his right to N. Haynes), Johnstown, Pa. 112,471.—Revolving Firearm.—Edwin S. Leaycroft, Brooklyn, N. Y., assignor by mesne assignment, to "Colt's Patent Firearms Manufacturing Company," Hartford, Conn. 112,472.—Revolving Firearm.—Edwin S. Leaycroft, Brooklyn, N. Y., assignor, by mesne assignment, to "Colt's Patent Firearms Manufacturing Company," Hartford, Conn. 112,473.—Railroad Cattle-Guard Gate.—J. H. Mallory, La Porte, Ind. 112,474.—Back-reflecting Mirror.—Richard Mason (assignor to himself and Matthew Ely), Newark, N. J. 112,475.—Ventilator and Chimney Top.—James McGowan (assignor to himself and Daniel H. Waring), New York city. 112,476.—Apparatus for Rectifying and Refining Spirits.—Frederick Measey (assignor to himself and Henry D. Fling), Philadelphia, Pa. 112,477.—Tin Can.—John F. Merrill (assignor to himself and Alexander Stewart), Cincinnati, Ohio. 112,478.—Take-up Mechanism for Looms.—John Michna and Joseph Fischer, New York city. 112,479.—Combined Baker and Broiler.—Wm. H. Miller, Brandenburg, Ky. 112,480.—Shuttle for Sewing Machines.—James D. Moore, Grinnell, Iowa. 112,481.—Cotton Chopper and Grain Cultivator.—Daniel Mosely, Osark, Arkansas. 112,482.—Sad and Fluting Iron.—Frederick Myers, New York city. 112,483.—Reed for Organs and Melodeons.—Augustus Newell, Chicago, Ill. 112,484.—Straw Cutter.—Amon Park, Germanville, Iowa. 112,485.—Apparatus for Aging Whisky and Other Spirits.—Josiah Peiffer and Samuel Richards, Valonia, Pa. 112,486.—Combined Cotton and Corn Planter.—Louis A. Perrault (assignor to himself and Joseph Huber), Natchez, Miss. 112,487.—Faucet.—Solomon Pfleger, Reading, assignor to himself and J. S. Pfleger, Tamaqua, Pa. 112,488.—Treadle.—George K. Proctor, Salem, Mass. 112,489.—Lubricating Compound.—Victory Purdy, Poughkeepsie, N. Y. 112,490.—Fertilizer and Seeding Machine.—Archibald Putnam (assignor to Elizabeth Putnam), Owego, N. Y. 112,491.—Rotary Pump.—George W. Putnam, South Glens Falls, N. Y. 112,492.—Hat Brush.—Robert Dunbar Radcliffe, Palmyra, N. Y. 112,493.—Refrigerating Show Case.—Thomas L. Rankin, Lyndon, Kansas, assignor to himself and D. W. Rockwell, Elyria, Ohio. 112,494.—Device for Starting and Stopping Cars.—Philip Rhoads, Carlisle, Pa. 112,495.—Pipe-molding Machine.—George Richardson, Milwaukee, Wis. 112,496.—Sulky Cultivator.—Richard B. Robbins, Adrian, Mich. 112,497.—Hand Plow.—Nelson Rue, Harrodsburg, Ky. 112,498.—Mechanical Movement.—Edward G. Russell, Ravenna, Ohio. 112,499.—Railway Car Brake.—Lyman Alphonzo Russell, Shrewsbury, Vt. 112,500.—Stovepipe Cleaner.—David Sanford, Ashton, Ill. 112,501.—Twine Holder.—Joseph B. Sargent and Purmont Bradford (assignors to Sargent & Co.), New Haven, Conn. 112,502.—Dovetailing Machine.—James M. Seymour, Newark, N. J. 112,503.—Wooden Pavement.—Eaton Shaw, Portland, Me. 112,504.—Guard for Circular Saws.—George W. Shipman, Ischua, N. Y. 112,505.—Breech-loading Firearm.—Dexter Smith and Martin J. Chamberlin, Springfield, Mass. 112,506.—Spark Arrester.—James Smith, Altoona, Pa. 112,507.—Horse Hay Rake.—Solomon P. Smith, Waterford, N. Y. 112,508.—Plow.—S. M. Stewart, New Harrisburg, Ohio. 112,509.—Medical Compound for Treating Fever and Ague.—George E. Swan, Mount Vernon, Ohio. 112,510.—Device for Cooling Journals of Car Axles.—Henry G. Thompson, Milford, Conn. 112,511.—Cooling Journal of Car Axles.—Henry G. Thompson, Milford, Conn. 112,512.—Cooling Journal of Car-wheel Axles.—Henry G. Thompson, Milford, Conn. 112,513.—Device for Cooling Journals of Railway Cars.—Henry G. Thompson, Milford, Conn. 112,514.—Non-heating Handle for Sad Irons, etc.—William H. Towers, Boston, Mass. 112,515.—Lubricator.—John Erst Uhl, Renovo, Pa. 112,516.—Combined Corn Planter and Cultivator.—Franklin Underwood, South Rutland, N. Y. 112,517.—King Bolt.—Wendel Vondersaar, Indianapolis, Ind. 112,518.—Wheat Roaster.—George W. Waitt (assignor to himself and Robert B. Fitts), Philadelphia, Pa. 112,519.—Plaster Sower.—Thomas J. West, Alfred Center, N. Y. 112,520.—Ticket Holder.—Henry Wexel, Providence, R. I. 112,521.—Tobacco Press.—Abraham N. Zell, Lancaster, Pa. 112,522.—Combined Bag Holder and Scales.—William Zimmerman, Lebanon, Pa. Antedated February 25, 1871. 112,523.—Breech-loading Firearm.—James M. Mason, Washington, D. C. About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Various (2006). Scientific American, Volume XXIV., No. 12, March 18, 1871. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/19180/pg19180-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at , located at . www.gutenberg.org https://www.gutenberg.org/policy/license.html

Official lists of patents

Scientific American Supplement, No. 365, December 30, 1882 by Various, is part of the HackerNoon Books Series. You can jump to any chapter in this book . RECENT HYDRAULIC EXPERIMENTS. here RECENT HYDRAULIC EXPERIMENTS. At a late meeting of the Institution of Civil Engineers, the paper read was on "Recent Hydraulic Experiments," by Major Allan Cunningham, R.E. This paper was mainly a general account of some extensive experiments on the flow of water in the Ganges Canal, lasting over four years—1874-79. Their principal object was to find a good mode of discharge measurements for large canals, and to test existing formulæ. There are about 50,000 velocity, and 600 surface-slope measurements, besides many special experiments. The Ganges Canal, from its great size, from the variety of its branches abounding in long straight reaches, and from the power of control over the water in it, was eminently suited for such experiments. An important feature was the great range of conditions, and, therefore, also of results obtained. Thus the chief work was done at thirteen sites in brickwork and in earth, some being rectangular and others trapezoidal, and varying from 193 ft. to 13 ft. in breadth, and from 11 ft. to 7 in. in depth, with surface-slopes from 480 to 24 per million, velocities from 7.7 ft. to 0.6 ft. per second, and discharges from 7,364 to 114 cubic feet per second. For all systematic velocity measurements, floats were exclusively used, viz., surface floats, double floats, and loaded rods. Their advantages and disadvantages had been fully discussed in the detailed treatise "Roorkee Hydraulic Experiments"—1881. They measured only "forward velocity," the practically useful part of the actual velocity. The motion of water, even when tranquil to the eye, was found to be technically "unsteady;" it was inferred that there is no definite velocity at any point, and that the velocity varies everywhere largely, both in direction and in magnitude. The average of, say, fifty forward velocity measurements at any one point was pretty constant, so that there must be probably average steady motion. Hence average forward velocity measurements would be the only ones of much practical use. To obtain these would be tedious and costly, and special arrangements would be required to obviate the effects of a change in the state of water, which often occurred in a long experiment, as when velocities at many points were wanted. As to surface-slope its measurement—from nearly 600 trials—was found to be such a delicate operation that the result would be of doubtful utility. This would affect the application of all formulas into which it entered. The water surface was ascertained, on the average of its oscillations, to be sensibly level across, not convex, as supposed by some writers. There were 565 sets of vertical velocity measurements combined into forty-six series. The forty-six average curves were all very flat and convex down stream—except near an irregular bank—and were approximately parabolas with horizontal axes; the data determined the parameters only very roughly; the maximum velocity line was usually below the service, and sank in a rectangular channel, from the center outward down to about mid-depth near the banks. Its depression seemed not to depend on the depth, slope, velocity, or wind; probably the air itself, being a continuous source of surface retardation, would permanently depress the maximum velocity, while wind failed to effect this, owing to its short duration. On any vertical the mid-depth velocity was greater than the mean, and the bed velocity was the least. The details showed that the mid-depth velocity was nearly as variable from instant to instant as any other, instead of being nearly constant, as suggested by the Mississippi experimenters. The measurement of the mean velocity past a vertical was thought to be of fundamental importance. Loaded rods seemed by far the best for both accuracy and convenience in depths under 15 ft. They should be immersed only 0.94 of the full depth. The chief objection to their use, that—from not dipping into the slack water near the bed—they moved too quickly, was thus for the first time removed. A double float with two similar sub-floats at depths of 0.211 and 0.789 of the full depth would also give this mean with more accuracy and convenience than any instrument of its class; this instrument is new. Measurement of the velocity at five eighths depth would also afford a fair approximation. One hundred and fourteen average transverse velocity curves were prepared from 714 separate curves. These average curves were all very flat, and were convex down stream—over a level or concave bed—and nearly symmetric in a symmetric section. The velocity was greatest near the center, or deepest channel, decreased very slowly at first toward both banks, more rapidly with approach to the banks or with shallowing of the depth, very rapidly close to the banks, and was very small at the edges, possibly zero. The figure of the curve was found to be determined by the figure of the bed, a convexity in the bed producing a concavity in the curve and , and more markedly in shallow than in deep water. Curves on the same transversal, at the same site, and with similar conditions, but differing in general velocity, were nearly parallel projections. At the edges there was a strong transverse surface flow from the edge toward mid-channel, decreasing rapidly with distance from the edge. The discussion showed that it was almost hopeless to seek the geometric figure of the curves from mere experiment. vice versa Five hundred and eighty-one cubic discharges were measured under very varied conditions. The process adopted contained three steps: (1) Sounding along about fifteen float courses, scattered across the site in eight cross sections; time, say four hours. (2) Measurement of the mean velocities through the full depths in those float courses, each thrice repeated; time, say four hours. (3) Computation, say two hours. This process was direct and wholly experimental; each step was done in a time which gave some chance of a constant state of water. From an extended comparison of all results under similar conditions, it appeared that the above process yielded, under favorable circumstances, results not likely to differ more than 5 per cent. The sequel showed that in a channel with variable regimen, a discharge table for a given site must be of at least double entry, as dependent on the local gauge-reading, and on the velocity or surface-slope. Special attention was paid to rapid approximations to mean sectional velocity. The mean velocity past the central vertical, the central surface velocity, and Chézy's quasi-velocity—i.e., 100 × √( R × S ) where R=the hydraulic mean depth, and S=surface slope—were tried in detail; thus 100, 76, and 83 average values thereof respectively were taken from 581, 313, and 363 detail values. The ratios of these three velocities to the mean velocity were taken out, and compared in detail with Bazin's and Cutter's coefficients. Other formulæ were contrasted also in slight detail. Kutter's alone seemed to be of general applicability; when the surface slope measurement is good, and the rugosity coefficient known for the site—both doubtful matters—it would probably give results within 7½ per cent. of error. Improvement in formulæ could at present be obtained only by increased complexity, and the tentative research would be excessively laborious. Now the first two ratios varied far less than the third; thus their use would probably involve less error than the third, or approximation would be more likely from direct velocity measurement than from any use of surface slope. The connection between velocities was probably a closer one than between velocity and slope; the former being perhaps only a geometric, and the latter a physical one. The mean velocity past the central vertical was recommended for use, as not being affected by wind; the reduction coefficient could at present only be found by special experiment for each site. Three current meters were tried for some time with a special lift, contrived to grip the meter firmly parallel to the current axis, so as to register only forward velocity, and with a nearly rigid gearing wire. No useful general results were obtained. Ninety specimens of silt were collected, but no connection could be traced between silt and velocity; it seemed that the silt at any point varied greatly from instant to instant, and that the quantity depended not on the mean velocity, but probably on the silt in the supply water. Forty measurements of the evaporation from the canal surface were made in a floating pan, during twenty five months. The average daily evaporation was only about 1/10 in. The smallness of this result seemed to be due to the coldness of the water—only 63 deg. in May, with 165 deg. in the sun and 105 deg. in shade. Lastly, it must suffice to say that great care was taken to insure accuracy in both fieldwork and computation. About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Various (2006). Scientific American Supplement, No. 365, December 30, 1882. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/18763/pg18763-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at , located at . www.gutenberg.org https://www.gutenberg.org/policy/license.html

RECENT HYDRAULIC EXPERIMENTS

Totem and Taboo by Sigmund Freud, is part of the HackerNoon Books Series. You can jump to any chapter in this book here . TRANSLATOR’S INTRODUCTION TRANSLATOR’S INTRODUCTION When one reviews the history of psychoanalysis one finds that it had its inception in the study of morbid mental states. Beginning with the observation of hysteria and the other neuroses Professor Freud gradually extended his investigations to normal psychology and evolved new concepts and new methods of study. The neurotic symptoms were no longer imaginary troubles the nature of which one could not grasp, but were conceived as mental and emotional maladjustments to one’s environment. The stamp of degeneracy impressed upon neurotics by other schools of medicine was altogether eradicated. Deeper investigation showed conclusively that a person might become neurotic if subjected to certain environments, and that there was no definite dividing line between normal and abnormal. The hysterical symptoms, obsessions, doubts, phobias, as well as hallucinations of the insane, show the same mechanisms as those similar psychic structures which one constantly encounters in normal persons in the form of mistakes in talking, reading, writing, forgettin, dreams and wit. The dream, always highly valued by the populace, and as much despised by the educated classes, has a definite structure and meaning when subjected to analysis. Professor Freud’s monumental work, The Interpretation of Dreams , marked a new epoch in the history of mental science. One might use the same words in reference to his profound analysis of wit Faulty psychic actions, dreams and wit are products of the unconscious mental activity, and like neurotic or psychotic manifestations represent efforts at adjustment to one’s environment. The slip of the tongue shows that on account of unconscious inhibitions the individual concerned is unable to express his true thoughts; the dream is a distorted or plain expression of those wishes which are prohibited in the waking states, and the witticism, owing to its veiled or indirect way of expression, enables the individual to obtain pleasure from forbidden sources. But whereas dreams, witticisms, and faulty actions give evidences of inner conflicts which the individual overcomes, the neurotic or psychotic symptom is the result of a failure and represents a morbid adjustment. The aforementioned psychic formations are therefore nothing but manifestations of the struggle with reality, the constant effort to adjust one’s primitive feelings to the demands of civilization. In spite of all later development the individual retains all his infantile psychic structures. Nothing is lost; the infantile wishes and primitive impulses can always be demonstrated in the grown-up and on occasion can be brought back to the surface. In his dreams the normal person is constantly reviving his childhood, and the neurotic or psychotic individual merges back into a sort of psychic infantilism through his morbid productions. The unconscious mental activity which is made up of repressed infantile material for ever tries to express itself. Whenever the individual finds it impossible to dominate the difficulties of the world of reality there is a regression to the infantile, and psychic disturbances ensue which are conceived as peculiar thoughts and acts. Thus the civilized adult is the result of his childhood or the sum total of his early impressions; psychoanalysis thus confirms the old saying: The child is father to the man. It is at this point in the development of psychoanalysis that the paths gradually broadened until they finally culminated in this work. There were many indications that the childhood of the individual showed a marked resemblance to the primitive history or the childhood of races. The knowledge gained from dream analysis and phantasies , when applied to the productions of racial phantasies, like myths and fairy tales, seemed to indicate that the first impulse to form myths was due to the same emotional strivings which produced dreams, fancies and symptoms . Further study in this direction has thrown much light on our great cultural institutions, such as religion, morality, law and philosophy, all of which Professor Freud has modestly formulated in this volume and thus initiated a new epoch in the study of racial psychology. [7] [8] I take great pleasure in acknowledging my indebtedness to Mr Alfred B. Kuttner for the invaluable assistance he rendered in the translation of this work. A. A. BRILL. About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Sigmund Freud (2021). Totem and Taboo. Urbana, Illinois: Project Gutenberg. Retrieved October 2022 https://www.gutenberg.org/cache/epub/41214/pg41214-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org , located at https://www.gutenberg.org/policy/license.html.

TRANSLATOR’S INTRODUCTION

In our , we previewed the Framework. For this article, let’s create a small demo project. To start with, let’s set up a scenario for the demo. previous NativeScript article SimpleFileTransfer is a virtual file locker. Users can sign up for the service and get 100 MB of free virtual storage space. Users can then download and upload files on a server. Users will be able to increase their storage space by filling a form. Let’s jot down the App functionalities before moving ahead: Signup: User can signup for the app. Login: Authenticates user. Details Page: Provides user details like current quota and total space. Also, we can display a list of files. Download file: Download file from the server to a device. Upload file: Upload files from a device to the server. Increase Quota: Increases storage quota of a user by a specified amount. You can find the whole code on . GitHub Structuring the Backend The backend must provide the functionalities of managing routes, providing basic authentication and storage, and facilitating file transfers. Based on the requirements above, we will be using the following stack: Node: Server : Middleware Express : ORM Middleware Sequelize SQLite: Database We will also be using libraries like and for specific functionalities that will be explained later on. multer bcrypt Initializing the Backend Project We will be using express-generator to set up the project. Install globally using: express-generator npm install express-generator -g Start a new project using the command: express file-server Navigate to the directory and install the dependencies using . Also, install the following dependencies: file-server npm install npm install multer async sequelize sqlite3 body-parser bcrypt --save Additionally, we will be creating some extra folders for: Database: Storing SQLite DB & DB script. Model: Storing Models. Upload: Temporarily storing uploaded files. Storage: storing file for specific users. Starting with Sequelize is an ORM middleware for SQLite, MySQL, PostgreSQL and MSSQL. For small projects, it’s convenient to use the Sequelize + SQLite combo. Sequelize In our current scenario, we require only one Model. We will define our model user as follows: const User = sequelize.define('user', {uid: { type: Sequelize.INTEGER, primaryKey: true, autoIncrement: true },username:  { type: Sequelize.STRING, unique: true },password: Sequelize.STRING,quota: {type: Sequelize.INTEGER, defaultValue: 104857600},createdAt: Sequelize.DATE,updatedAt: Sequelize.DATE,}) We can use Sequelize’s to initialize Models Table in a database. To initialize users table, we will be using the code below. Model.sync User.sync({force: true}).then(() => {// Table created}); We will store the user model in the file in the model folder. user.js This part is pretty straightforward. For signup, the server accepts a username and password and stores it in the database. We will be using the bcrypt library to salt the passwords. As shown below, we are salting the password 10 times before storing it in the database. We are using Sequelize’s to store the value. Once a user is created, we will create a directory on our server for his uploads. Model.create The code is as below: router.post('/', function(req, res, next) {console.log(req);bcrypt.hash(req.body.password, 10, function(err, hash) {User.create({ username: req.body.username, password: hash }).then(user => {if (!fs.existsSync('storage/'+user.get('uid'))){fs.mkdirSync('storage/'+user.get('uid'));}res.send({status: true, msg: 'User created', uid: user.get('uid')});}).catch(err => {res.send({status: false, msg: err });})});}); For login, the server accepts a username and password and validates it against the database. We are using to get the database record. We use to compare passwords. Model.findAll bcrypt.compare router.post('/', function(req, res, next) {console.log(req);User.findAll({attributes: ["username", "password"],where: {username: req.body.username}}).then(dbQ => {if(dbQ.length > 0) {bcrypt.compare(req.body.password, dbQ[0].dataValues.password, function(err, result) {if (result == true){res.send({status: true, msg: 'Login Success'});} else {res.send({status: false, msg: 'Incorrect Password'});}});} else {res.send({status: false, msg: 'User not found'});}});}); Defining the Users Route An authenticated user is allowed to perform the following functions: Upload file Download file Get Details Increase quota Let’s define the routes for those functions: Upload: POST /users/:id/upload Download: GET /users/:id/download/:filename Details: GET /users/:id/details Increase Quota: POST /users/:id/increasequota Uploading a File to the Server We will be using to handle uploads. multer The multer library is useful to handle multi-part form data. Initially, we will be uploading the file to the uploads folder. Then, the file will be moved to folder where uid is user id. /storage/uid var storage = multer.diskStorage({destination: function (req, file, cb) {cb(null, 'uploads/')},filename: function (req, file, cb) {cb(null, file.originalname )}}); router.post('/:id/upload', upload.single('fileparam'), function(req, res, next) {if (!req.file) {console.log("No file received");return res.send({success: false,msg: "Error Uploading files"});} else {console.log('file received');fs.rename('uploads/'+ req.file.originalname, 'storage/'+req.params.id+'/'+req.file.originalname, function (err) {if (err) {console.log(err);return;}return res.send({success: true,msg: "File Uploaded"})});}}); The method is used for handling uploads. This route is expecting a file with name in the URL call. This is quickly done by adding a name attribute an HTML form. We will need the name attribute app side. upload.single fileparam Download Route ExpressJS provides us with a function to set the download route, conveniently called download. This is the logic we are following: A user logs into the app. He selects a file and initiates the download. The server receives a request with userid and filename. The server sends the file back to the user. The code for the route is below router.get('/:id/download/:filename', function(req, res, next) {const file = 'storage/'+req.params.id + '/' + req.params.filename;res.download(file);}); Increase User Quota Route We will be invoking to adjust the quota. By default, we have 104857600 bytes — which is equivalent to 100 MB — assigned to each user. You can find the query below. Model.update router.post('/:id/increasequota', function(req, res, next) {User.update({quota: req.body.quota,}, {where: {uid: req.params.id}}).then(response => {res.send({status: true, msg: "Quota Increased"});}).catch(err => {res.send({status: false, msg: err});});}); User Details Route This is a route which we will be using for fetching multiple data, such as: Storage Limit of user: from the DB, Current File Space occupied: from the directory, /storage/userid Space Remaining: it’s just Point 1 — Point 2, File List: list of Files, We can fetch the storage limit of a user using . For fetching file names and storage space, we are using , and . Model.findAll fs .readdir fs.stat async function getStorageSpace(relpath) {let space = 0;let fileNames = [];let promise = new Promise(function (resolve, reject) {fs.readdir(relpath, function (err, items) {if (err){reject(err);}fileNames = items;let filesArr = items.map(function (val) {return relpath + '/' + val;});async.map(filesArr, fs.stat, function (err, results) { for (let i = 0; i < results.length; i++) {  
         if (err) {  
           reject(err);  
         }  
         space = space + results\[i\].size;  
       }  
       resolve({fileNames: fileNames, space: space });  
     });  
   });  
 });  
 return promise; } function getStorageLimit(uid){let promise = new Promise(function (resolve, reject) {User.findAll({attributes: ["quota"],where: {uid: uid}}).then(dbQ => { if(dbQ.length < 1) {  
       reject("Quota Not Found")  
     } else {  
       resolve(dbQ\[0\].dataValues.quota);  
     }       
   }).catch(err => {  
     reject(err);  
   });  
 });  
 return promise; } router.get('/:id/details', function(req, res, next) {let it;let relpath = 'storage/'+req.params.id;Promise.all([getStorageSpace(relpath), getStorageLimit(req.params.id)]).then(result => { res.send({storageLimit: result\[1\], occupiedSpace: result\[0\].space, fileNames: result\[0\].fileNames, remainingSpace: result\[1\]- result\[0\].space});  
 }) }); The code works on assumption that user is not allowed to create a subdirectory in his folder. N.B.: The code for enforcing storage limit will be discussed later in the article. NativeScript App For the app side, we will be taking an alternative approach. A demo project based on Angular-Blank template will be shared with users. A significant part of this article will cover details about plugins concerning the plugin functionalities. Consuming Web Services We are consuming data from simple web services for Login / Signup / User Details Page. As mentioned in the , we can access these webservices using the . The basic steps are as follows: previous article HttpClient Module Import in the PageModule. NativeScriptHttpClientModule Import and in Component or Provider. HttpClient HttpHeaders Consume the URL as you will in an Angular application. We will set header to . Content-Type application/json For the JavaScript/TypeScript templates, we can use the NativeScript Core module. The function provides the required framework to consume webservices. Alternatively, we can also use the module. http http. getJson fetch As a response from the server, we will be receiving the of a user. After authentication, we need to store the so we can allow a mobile user to access . uid uid /users/uid route Storing Data The NativeScript framework doesn’t have any method to store data persistently. We can add that functionality using plugins. We are going to look at two of these plugins. : This plugin provides an interface for the SQLite library. This works well if your app needs to store a large volume of records. Install it with: nativescript-sqlite tns plugin add nativescript-sqlite : This plugins provides a key value API for string data, similar to . This works well if your app doesn't have lot of records. Install it with: nativescipt-localstorage window.localstorage tns plugin add nativescript-localstorage The demo app will be using . nativescript-localstorage Uploading Files from a Device to a Server Let’s break this functionality into subtasks: Choose Files from the device. Get File Path. Upload File over uploads WebService. To choose a file and get a file path, we will be using the plugin. The plugin has multiple modes and we can customize it for specific use cases. You can check the plugin documentation . nativescript-mediapicker here To select a file, first, we need to define extensions. This is different for both OSes. For Android devices, we have to use file extensions based on mime types like For iOS devices, we have to define extensions from list for Unified Type identifiers: let extensions = ["xlsx", "xls", "doc", "docx", "ppt", "pptx", "pdf", "txt", "png"] let extensions = [kUTTypePDF, kUTTypeText]; You can read more about UTIs and . here here The code for invoking is as below: filepicker let options: FilePickerOptions = {android: {extensions: extensions,maxNumberFiles: 1},ios: {extensions: extensions,multipleSelection: false}}; let mediafilepicker = new Mediafilepicker();mediafilepicker.openFilePicker(options); `mediafilepicker.on("getFiles", function (res) {let results = res.object.get('results');console.dir(results);}); mediafilepicker.on("error", function (res) {let msg = res.object.get('msg');console.log(msg);}); mediafilepicker.on("cancel", function (res) {let msg = res.object.get('msg');console.log(msg);});` As above, we will receive the filepath of a file in the event. getFiles We will send the file to the server using the plugin. You can read about the plugin . nativescript-background-http here Earlier, we defined the route. As mentioned earlier, our server is expecting the file in the attribute named . /users/:id/upload fileparam The background provides us with two functions: and . Since we need to set the name attribute, we will be using the function. http uploadFile multipartUpload multiPartUpload let session = bgHttp.session("image-upload");let request: bgHttp.Request = {url: Config.apiUrl  + '/users/' + localStorage.getItem('uid') + '/upload'   ,method: "POST",headers: {"Content-Type": "multipart/form-data"},description: 'FileName'};let params = [{name: 'file',filename: path}];let task: bgHttp.Task = session.multipartUpload(params, request);task.on("error", (e) => {reject(e);});task.on("complete", (e) => {resolve(e);}); Downloading a File to the Device We will be using the core , and modules to achieve the result. Both Android and iOS handle downloads differently. We will be using and variables from platform module to segregate the code. file-system platform utils isAndroid isIOS The file-system module provides us with a sub-module. Three predefined folders for both Android and iOS are available: knownFolders knownFolders.currentApp() knownFolders.documents() knownFolders.temp() Additionally, an provides us with some other predefined folders. E.g: iOS sub-module knownFolders.ios.download knownFolders.ios.sharedPublic iOS Code On an iOS scenario, this is straightforward: Show a list of server files. Download the files to the documents folder. List downloaded files in a separate view Use the function to open the file. utils.openFile To download the files, we will be using the module of the NativeScript framework. The function can be used to fetch files from the server and save them to a specific file location. The snippet for iOS is below: http getFile let filePath: string = path.join(knownFolders.documents().path, fileName);getFile(download_url + fileName, filePath).then((resultFile) => {// The returned result will be File object}, (e) => {console.log(e); Once the file has been downloaded, we can use the function from the module to open a file on iOS. openFile utils Android Code The Android side of coding is a bit trickier. The locations of the module are as below. knownFolders currentFolder: /data/data/:appid/files/app documents: /data/user/:androiduser/:appid/files temp: /data/user/:androiduser/:appid/cache As you can see, all the folders are located in . is inaccessible to normal users. Furthermore, external apps won't be able to access the files in those folders. Also, there is no function for Android. /data /data openFile As of now, the best we can do is: Show a list of server files. Download a file to a user accessible location. List the files present in the location. To implement the functionality, we will be using a bit of native code.  Before moving ahead, we will have to install with: tns-platform-declarations npm i tns-platform-declarations --save Create a file in the root folder and add the following lines: reference.d.ts `/// <reference path="./node_modules/tns-platform-declarations/ios.d.ts" />``/// <reference path="./node_modules/tns-platform-declarations/android.d.ts" />` You can check the for more details. readme provides us with a function to access the external storage. Android OS We will be using the constant and the function to create a publicly accessible download location. DIRECTORY_DOWNLOADS getExternalStoragePublicDirectory We will append a path “SimpleFileTransfer” to create a custom and . folderPath filePath const androidDownloadsPath = android.os.Environment.getExternalStoragePublicDirectory(android.os.Environment.DIRECTORY_DOWNLOADS).toString();const androidFolderPath = fs.path.join(androidDownloadsPath, "SimpleFileTransfer");const filePath: string = fs.path.join(androidFolderPath, fileName);getFile(download_url + fileName, filePath).then((resultFile) => {// The returned result will be File object}, (e) => {console.log(e); If you check your file explorer, a new directory will be created in the Downloads folder called SimpleFileTransfer. You will find all the files downloaded there. Listing Downloaded Files We will be using the module. The Folder class of the module has a function which allows us to list files in a folder. As with in Node.js, we can only list the files. file-system file-system getEntities fs.readdir For iOS, the path is const folderPath: string = fs.knownFolders.documents().path; For Android, the path is const androidDownloadsPath  =  android.os.Environment.getExternalStoragePublicDirectory(android.os.Environment.DIRECTORY_DOWNLOADS).toString(); `const  folderPath=  fs.path.join(androidDownloadsPath, "SimpleFileTransfer");` To access the Folder functions, we define a folder using let internalFolder = fs.Folder.fromPath(folderPath); Then, we use to get a list of files: getEntities internalFolder.getEntities().then((entities) => {// entities is array with the document's files and folders. entities.forEach((entity) => {  
               let  fileSize  =  fs.File.fromPath(entity.path).size;  
                   this.listArray.push({  
                       name: entity.name,  
                       path: entity.path,  
                       lastModified: entity.lastModified.toString(),  
                       size : fileSize  
                   });  
               });                    
           }).catch((err) => {  
               // Failed to obtain folder's contents.  
               console.log(err.stack);  
           }); Additionally, we have used the size property of File class to get file size. Enforcing Storage Limit The storage limit can be enforced in two ways: Upload file to the server → Checking remaining space → Reject the upload on the server side. Check remaining space using webservice → Check file size → Cancel the upload on the app side. To enforce the former, we can modify the upload route as below: Promise.all([getStorageSpace(relpath), getStorageLimit(req.params.id)]).then(result => {if (result[1] - result[0].space > req.file.size){fs.rename('uploads/'+ req.file.originalname, 'storage/'+req.params.id+'/'+req.file.originalname, function (err) {if (err) {return res.send({success: false,msg: "Error Uploading files"});}return res.send({success: true,msg: "File Uploaded"})});} else {return res.send({success: false,msg: "Storage Limit Exceeded"});}}) To enforce the latter, we get the file size of the file selected by the plugin and check it against the space remaining using the details webservice. mediafilepicker `let  fileSize  =  fs.File.fromPath(results[0].file).size;` if(fileSize < remainingSpace){// Send To server}`else {// alert user about lack of space} Closing Thoughts This demo covers quite a few different concepts. We divided the solution in a series of functionalities. We used core NativeScript for UX, interacting with the backend, file system management, and Routing. We extended the framework by installing plugins for functionalities like picking files. Going further, we used a bit of native code for solving a specific problem. Using NativeScript allowed us to develop the app faster for both platforms as against individually. If you want to learn how you can secure your NativeScript source code against client-side attacks, sign up for our free upcoming webinar on “ ”. Also be sure to check our . Best Practices for Securing Your Mobile Apps tutorial Originally published at blog.jscrambler.com .

How to Create a File Storage Mobile App with NativeScript 5

A comprehensive resource list for building engaging Augmented and Virtual Reality experiences using Web technologies This post originally appeared on the Halo Labs blog A few months ago I joined Halo Labs to help build our AR/VR design and prototyping platform. After the first interview, I received a “take home” exercise, to build a simple VR scene. While I was excited to build a VR app for the first time, I was also a bit afraid. I’m coming from a web development background and I never worked on a VR project before. To my surprise, it took me roughly three hours to finish the exercise, and it even looked pretty good (well, at least to me…). Over the past six months, whenever I told someone that I’m developing a VR product using Web technologies, I got puzzled looks. The will take place in two weeks, and I thought it’s a great time to show web developers that . first annual WebXR week VR & AR + Web technologies = ❤ The main goal of this post is to allow Web developers to enter the AR/VR world quickly and easily. The approach I have taken is not to write a guide about a specific technology or library, but rather to build a “curriculum” that will take you from zero to expert, so you would be able to build complex AR/VR experiences.  Even if you don’t plan to develop AR/VR experiences, reading this guide will give you a glimpse into the current state of the WebXR world. Let’s begin. Starting the journey — Getting to know the VR world Before we begin, let’s line up the terms: Virtual Reality is the use of computer technology to create a environment, so when you are in VR, you are viewing a completely different reality than the one in front of you. Augmented Reality (AR) on the other hand, is an version of reality created by adding digital information on your real-life reality (like in Pokemon GO). The term XR is often used to described any of the two. simulated enhanced While you could easily skip this step and jump directly to the WebVR frameworks, investing some time learning the basics of the XR world will greatly improve your learning speed and understanding down the road. The following resources will help you gain some background on VR and AR development, as well as the required (very basic) mathematical background: course by Udacity — This free course is a great place to start. The course introduces the main VR platforms available today and explains how they work while teaching some basic (but important!) VR terms. Introduction to Virtual Reality — Knowing the meaning of those basic XR terms will help you better understand articles and XR frameworks documentation. Another good resource is website. I really like their infographics section, as it helped me to get my head around some VR terms and topics. VR/AR Glossary The VR Glossary Basic 3D math — The subject I was most afraid of when I entered the VR world was math. I’m not a big math fan, and I thought that dealing with 3D requires a thorough math knowledge. Luckily, it turned out that I was wrong. The frameworks I’ll present below are relatively “high level” and doesn’t require any mathematical background. From my experience, the only important thing to know before moving on is . the difference between the left and right-handed coordinate systems Rendering 3D content on the web Now that we have some basic understanding of the XR world, we can start looking at XR web frameworks. The main framework for XR development is (supported by Mozilla). The next section will go deeper into A-Frame, but before that, it’s important to understand how A-Frame is built in order to use it effectively. Let’s dive in! A-Frame In 2007, Mozilla first introduced Canvas 3D, which allowed rendering interactive 3D graphics on the web. The next step was to expose an API, and by 2009 started the WebGL Working Group. The first version of the specification was released in 2011.But what exactly is WebGL? to quote from Mozilla: The Khronos Group WebGL enables web content to use an API based on OpenGL ES 2.0 to perform 2D and 3D rendering in an HTML in browsers that support it without the use of plug-ins. WebGL programs consist of control code written in JavaScript and shader code (GLSL) that is executed on a computer's Graphics Processing Unit (GPU) _canvas_ In short, WebGL is an API that enables rendering 3D content in the browser, without the need to use plug-ins. Today, all main browsers support the WebGL API, so we can safely use it to render 3D content on the web. The main problem? writing WebGL is hard and tedious. It’s enough to see the required to display simple 2D shapes to get discouraged. The solution? using Three.js. amount of code The aim of the project is to create an easy to use, lightweight, 3D library. The library provides <canvas>, <svg>, CSS3D and WebGL renderers.(source: ) Three.js GitHub page Three.js is a “high level” library that simplifies the creation of WebGL environments. It handles the lower level programming for you and lets you focus on building the scene. To see how much it simplifies the development, take a look at the code example below, which on the screen: renders an animated 3D cube In the above code example, we initialize the scene, the camera (which is our “eyes” in the scene) and the renderer. Then, we create a box geometry, which defines the cube , a material which defines how it’ll and finally we create a cube by combining the two into a mesh. After that, we add the cube to the scene and attach a simple animation to constantly rotate it. Finally, we render the scene. shape look This is a big improvement from the hundreds of lines of WebGL code, but it’s still not very simple. In order to display a cube, you have to understand what’s a material, a mesh, a renderer and how they all connect together. In addition, presenting 3D content is not the end of the story. In order to create “serious” VR content, we’ll also have to allow user input, physics, integrating with various VR headsets, and more.While all of these can definitely be built in three.js, it’ll be difficult to do so without deeper understanding in the 3D and VR domains.But don’t worry! A-Frame to the rescue! A-Frame — VR for the people The A-Frame framework was created in 2015 by the Mozilla VR team in order to allow web developers and designers to author 3D and VR experiences with HTML without having to know WebGL. A-Frame is based on HTML and the DOM, which makes it very accessible and easy to use. While using only the HTML layer allows getting an impressive result, HTML is only the outermost abstraction layer of A-Frame. **Underneath, A-Frame is an entity-component framework for three.js that is exposed declaratively.**A-Frame’s true power embodied in the last sentence, so let’s break it down to make sure we understand it: A-Frame is an entity-component framework for three.js To quote : Wikipedia ( ) is an architectural pattern […] An ECS follows the principle that allows greater flexibility in defining entities where every object in a scene is an entity (e.g. enemies, bullets, vehicles, etc.). Every Entity consists of one or more components which add additional behavior or functionality. Therefore, the behavior of an entity can be changed at runtime by adding or removing components. Entity–component–system ECS Composition over inheritance Let’s clarify with an example:Say I want to build a vehicle with the ESC pattern. Vehicle entity, composed of multiple components First, I would need a vehicle entity, which is practically an object with an Id. Next, I would use components to define the vehicle’s look and behavior. I would have multiple components such as color, wheels, seats, and engine. Finally, composing all those components into the entity we created earlier will give us a functional vehicle entity. While the above example is very simplistic, it should give you a rough idea of what an entity-component architecture is. A-Frame allows writing Three.js code in an ECS way, which makes VR development much easier. One main reason is that ECS makes it very easy to reuse components — so If I built a component, most chances you can use it too. The A-Frame community is taking advantage of that, and there is a which is available for you to use. Now that we understand the first part of the sentence, let’s examine the second part : big library of components that is exposed declaratively This part refers primarily to the HTML abstraction layer. This layer allows us to build a scene declaratively, which means we create a scene by defining it should do, and not it should do it. It can be done thanks to the underlying layers which allow us to create components. After we create a component, we can just say we want to do — the component already knows (that’s what the component code is all about). what how what how Now that we understand what A-Frame is and how it works, let’s see A-Frame’s Hello-World example: Copied from . You can move in the scene using the keyboard. A-Frame’s official examples In this example, every tag under is a Primitives are just syntactic sugar for entities with default components. For example, the primitive is an entity with multiple components (such as depth, height, and width) added by default. Each HTML property is a component added to these entities— we add (or override the default) position, rotation, color, and shadow components to our box entity. a-scene primitive. a-box A-Frame provides a set of primitives to help you create basic scenes quickly and easily, and you can also create your own primitives. I won’t get deeper into A-Frame since it’s not the purpose of this article, but here are some good resources to jumpstart your A-Frame journey: — A-Frame official documentation is quite comprehensive and I highly recommend reading it. It probably contains the answers for all your “beginner questions”, so make sure to check it out before searching other places. A-Frame documentation — An interactive A-Frame course built by A-Frame creators. Using Glitch, the course provides step-by-step exercises to help you get started. A-Frame school — Despite the fact that using A-Frame with React might result with poor performance, I find it to be a great combination (actually, that’s our setup here in Halo Labs). If you like React, this tutorial is using and it’s a great place to start. (p.s — If you prefer Angular, check out ) Creating Your First WebVR App using React and A-Frame aframe-react angular-aframe-pipe Augment your skills So far we talked about VR, but what about AR?Since we still don’t have any broad consumer AR headsets today, the existing WebAR solutions mainly focus on . mobile AR Today, there are three main libraries you can use to build AR scenes, all three work with A-Frame, but each has different capabilities. Let’s go over them one by one: AR.js provides both an A-Frame and a three.js extension that allows building AR scenes. AR.js was built with WebGL and WebRTC, so it’s the only one of the three that works with almost every smartphone, regardless of its OS version. AR.js marker-based If you want to play with AR.js, check out Akash Kuttappa’s . article aframe-ar The common way to build mobile AR application is to use (for Android) or (for IOS) both are native SDK’s. In order to provide a way to use those SDK’s capabilities (like surface detection) on the web, Google released two experimental apps: and . which are actually browsers that expose a JavaScript API to the aforementioned capabilities. On top of that, they released a library called , which provides three.js helper functions for building AR experiences. Since A-Frame is built on three.js, was created in order to provide an easy to use A-Frame wrapper. How easy? all you need to do is to change your A-Frame scene tag from to and you have a working AR scene! ARCore ARKit WebARonARCore WebARonARKit three.ar.js aframe-ar <a-scene> <a-scene ar> If you want to play with aframe-ar, check out Uri Shaked’s . excellent article aframe-xr is based on and they both created by Mozilla. Its main difference from aframe-ar is that it complies with the proposed using the . The main implication is that aframe-xr enables building “progressive experiences” — experiences that change according to the device in use. Simply put, it allows you to move between AR and VR seamlessly.Here in Halo Labs we are big believers in the WebXR API, so aframe-xr is our chosen framework. aframe-xr three.xr.js WebXR Device API webxr-polyfill If you want to learn more about the WebXR API, check out . Also, Mozilla has regarding Progressive WebXR. Dan’s blog post a great blog post After playing with WebAR for a while, it’s obvious that it’s not yet mature. However, even today, using the libraries I mentioned above, you can build some impressive AR experiences. Down The Rabbit Hole So far we’ve covered all the basics. That’s enough to create basic AR/VR experiences and gain some confident in your abilities, but if you want to create some more complex stuff, you’ll need to extend your knowledge.Here are some resources to help you get deeper understanding: — A Udacity course teaching basic principles of 3D computer graphics (meshes, transforms, materials, and more). Interactive 3D Graphics — A series of posts written by Rachel Smith, teaching Three.js basics with a lot of code examples. Beginning with 3D WebGL — An introduction to Three.js. @necsoft talks about all the important stuff in one blog post. Three.js 101: Hello World! — The lower you go on abstraction level, the greater the mathematical knowledge required from you. From my experience, if you want to strengthen your math knowledge, Khan Academy is your best friend. Linear algebra — Khan academy — An example of how to implement a VR Minecraft demo using A-Frame. This step by step guide will help you better understand how to build a robust VR app with A-Frame. Building a Minecraft demo with A-Frame Content As we all know, on the internet- . This is also true for the process of creating XR experiences. In order to build convincing XR experiences, 3D assets are required. While the amount of free and easy 3D creation tools increases rapidly, many of us prefer to use existing content instead of creating it ourselves. Currently, there are 2 main sources for free 3D assets: content is king — A library containing thousands of 3D models for use in VR and AR applications. Poly models are published under license ( ), which means you can use them freely, even for commercial use, as long as you provide attribution to the author. Google Poly Creative Commons CC-BY 3.0 — A marketplace of 3D models that contains more than 2M models. Sketchfab contains thousands of free models, also licensed under Creative Commons license ( ). Sketchfab models are usually high quality, and as a result — “weigh” more. Sketchfab CC-BY 4.0 Both sites support multiple 3D formats, include . You can choose the required format when downloading the model. glTF It’s very easy to add models to an A-Frame scene, by using the primitive (there are as well): a-gltf-model loaders for other formats <a-gltf-model src={http://model.url} /> The easiest way to avoid CORS problems is to host your assets on a publicly accessible CDN. Mozilla provides one for free: https://cdn.aframe.io/ Final words As web developers, the AR/VR world often seems inaccessible. The truth is that the required tools for us to enter and create in this world already exist. Libraries like three.js and A-Frame allow us to use our existing web development skills to build rich VR scenes. In addition, complementary libraries add capabilities that enable the creation of AR scenes, and even progressive experiences that adapt to the capabilities of the device on which they run. Hopefully, my post will help other web developers enter the AR/VR world and together we can finally build the ! :) Metaverse

Building AR/VR with Javascript and HTML

When I started teaching undergraduate C during my master’s program, I did a lot of thinking about how I felt when I was a student sitting in these same classes just a few years before. And that time was characterised for me, as I’m sure it is for many students, by an overarching sense that this wasn’t “real” computer programming. All input and output in the course was performed through the terminal, but half of us had never even seen the terminal used before, and we certainly weren’t regularly running programs from one. In consumer software, the GUI reigns supreme. Is it any wonder I felt like the computer programming I was learning was somehow at odds with my experience as a user of software? programming Of course, this line of betrays some naivety in my younger self, but the problem was a valid one: when your audience is accustomed to interacting with a computer graphically, how do you make them feel empowered by what they’ve learned using purely text-based I/O? With this objective in mind, I wanted to produce a demonstration for the class that looked flashy and impressive, but required extensive computation to get there. This way, I would hopefully be able to convince a flock of disinterested undergraduates that they were most of the way toward being able to produce the sort of computer program they most strongly relate to. thinking I was lucky in one respect, since the course in question, being geared toward programming for engineers, featured a significant unit on numerical methods. All these students had just learned how to write numerical ODE solvers, which lie at the core of a wealth of physical simulations. Are physical sims computationally intensive? Check. Do they produce flashy and impressive results? You betcha. Is it within the capabilities of these students to write one? Well, they’ll be able to understand the code if it’s given to them, at any rate. Aforementioned flashy and impressive results of physical simulations I figured that a cloth simulation struck the perfect balance between complexity and spectacle. It’s effectively a solved problem at this point, with some implementations producing impressively realistic results (see below). So while it mightn’t have been the most revolutionary project, I knew that the problem was well-documented with plenty of supporting material, which was beneficial for a class demonstration. There are models of varying complexity, and the simpler ones are easy to follow without seeming trivial. The model selected treats the cloth as a set of point masses connected by springs. The good thing here was that it could be explained in terms of processes that required only a high school level of physics knowledge, and it was possible, without changing the underlying model, to add additional dynamics that improve accuracy if so desired. All cloth in this surreal video is computer-generated So at its core, the cloth is effectively a grid of particles, with each particle connected to its 8 immediate neighbours by springs like so: How do you obtain the dynamics of a model like this? If we have the position of each particle at a given instant in time, we can assume that the position a very short time later will be roughly this position plus the instantaneous velocity times that very short period of time. Congratulations, you’ve just understood how an ODE solver works. But to follow this method, we need to obtain an estimate of the velocity of each particle by summing the forces acting on them. We divide by mass, and presto, there’s an acceleration we can use to obtain an estimate of the velocity. How good is Newton’s Second Law? The forces we’d consider (at a minimum) to be acting on each particle are a weight force, and the 8 contributions from the 8 springs connected to it. If we wanted to model wind or collisions or whatever, we could add that as well. But essentially, the evolution of the system involves computing, for each time instant, the net force acting on each vertex; from this determining the acceleration vector; and from that finding the velocity and position vectors. The weight force is easy, that’s just a constant -9.8_m_ in the z direction. The springs are a little trickier. The force on a damped spring is resistant to both the amount it is currently stretched by, , and its current instantaneous velocity, . The formula is therefore: x v = - F kx-cv where k and c are constants. Visualisation of the forces acting on a damped spring There’s some trickiness here because the velocity in this case is the velocity between the two neighbouring particles. In any case, do that 8 times, once for each immediate neighbour, and sum the results to get the net force on the particle. relative Armed with these formulae and this model, I was able to put together a decent cloth simulation. In practise, I used a slightly more complex ODE solver called a , which made the simulation more robust, and less prone to instability. Given that this is the solver the students are taught about, using it was a great learning opportunity. Runge-Kutta solver For output, I just printed the resulting data to the terminal, one line to a time instant. Remember that the point of this program is to emphasise the importance of the computation itself, and I think it does a good job of that. A lot of effort goes into producing the numbers that are produced as output, both computational resources and mental effort in designing the program. But of course, if we can produce pretty pictures from this, we ought to. So, by writing some supplementary scripts, I took the output of the solver and rendered a series of frames using , which I stitched into a video. pbrt Fantastic stuff. And here’s the thing, there really wasn’t much post-processing necessary to get that result. I want to be able to convince any student starting their computer science journey that something like this is within their grasp. The renderer isn’t the important part of producing that video, our program is, because without it, there’s nothing to render. By the way, this simulation is far from perfect: there are a number of avenues to explore here to make our simulation more robust or accurate or versatile. We could check for self-intersections of the cloth, we can add additional springs to our model to prevent sharp edges forming at vertices, we could model collisions with solid objects, or add external forces such as wind. The code’s all public on ; feel free to clone it and make some improvements. Github So how did this go down? Well, I showed it to students, and a lot were duly impressed, which is of course flattering and encouraging, but it’s not something I’m all that interested in. Because the real metric for success is whether or not they believed it was within their abilities to do the same, and I hope they did. When you learn to program for the first time, you get this feeling that all your projects are just tiny parts of ‘real’ programs; or toy examples that don’t mean anything. So I think it’s increasingly important to keep students feeling like what they’re being taught is actually relevant in some way. By giving them examples of how their code might fit into some bigger picture, we empower them not just to continue studies in the field, but to start playing around with programming and perhaps end up making something incredible.

How a Piece of Cloth can get Students Interested in Programming

On this topic: | | Part 3 | | | Part 1 Part 2 Part 4 Part 5 Part 6 The was a bit long so we’re going to move forward in smaller increments. last article Let’s start with a discussion on how works in games. The 18th century Swiss mathematician, physicist, astronomer, logician and (quite a resume) Leonhard Euler devised a way for us to predict where an object’s going to be based on two things: its current position and its speed. We actually used it in our in the method of our class: movement engineer previous article update() Square this.x += 1 * movementMultiplier;this.y += 1.5 * movementMultiplier; Euler integration works wonders in games where speed is and it’s also very easy on the processor; unfortunately you’ll quickly find out it’s not quite enough if you’re planning on building a physics engine… it becomes highly inaccurate. Let’s visualize this: constant Euler integration In the image above, the distance between two peaks on the grid is ~30px, the speed of our ball is 60px every frame and we’re running this for 10 frames (at 60fps that’s 1/6 of a second). This seems fine… the movement is constant so it should be easy to work with, right?… well, not really; let’s add a wall in there: Between frames 5 and 6 you can see an impressively drawn wall; what’s even more impressive is that with the current logic, that ball will pass through the wall like it’s not even there. This might be cool if you’re trying to achieve teleportation, not so much if you’re reaching for collision. In a game were detecting multiple object collisions is necessary, if you take into account that each object has it’s own trajectory, speed and external forces acting on it… Euler integration proves insufficient. Another way would be using one of the but they can put a strain on the processor; it’s perfect for precision physics calculations but probably overkill for our purposes. Runge–Kutta methods The go to method in most games would be to use the equations of the French physicist Loup Verlet, specifically . The main difference is that with Verlet integration you’re calculating the speed of an object and not its position in the next frame. You do this by subtracting the previous position from the current position. Verlet integration I keep saying speed so I’m going to correct myself; . The difference between speed an velocity matters to us, because speed is ignorant of direction, whereas velocity is a vector quantity and it is direction aware; it’s a really small and hugely important distinction. we’re actually calculating velocity let velocity = currentPosition - previousPosition;position += velocity; Does this mean our collision problem goes away? Not really but it makes it easier to rectify; we can calculate the next state based on our current and previous states, enabling us to resolve any conflicts before we render. We’ll create a in the game engine and this will allow for other objects to use it if needed; for now it should: VerletModel expose getters and setters for the x and y velocities expose getters and setters for the x and y position values engine/models/VerletModel.js This model could potentially hold variables for other things like: , , and so on or it could be extended by another class that adds these features. The reasoning behind this is simple: all games have movement but not all games need complex physics. gravity friction rotation Let’s see an example; we’ll create another square that moves as described above and add a bit of acceleration and friction logic to our model. A classic MVC approach should do the trick: class which will extend : it will store all data related to our square as well as an method which will overwrite the default one in . SquareModel VerletModel update() VerletModel verletSquare/square/SquareModel.js You can see we’re using the , , and setters and getters from to calculate friction which we then add to the acceleration. x y vx vy VerletModel class which will extend **Scene (**for now; as this should extend , which we don’t have yet) SquareView DisplayObject verletSquare/square/SquareView.js The receives an instance of the and which it updates in its own method. You’ll also see that we’re storing a scene reference on the model, as this is needed to properly wrap the square to its parent scene. This is annoying and should be done automatically but we won’t worry about that yet. SquareView SquareModel SquareCtrl update() class which will extend SquareCtrl Keyboard verletSquare/square/SquareCtrl.js The has one job: to change the acceleration based on the currently pressed key. When we release a key, the friction is set to 0.94. This value will be multiplied with our velocity and the result added to our acceleration. SquareCtrl In the end we’ll get a friction effect which slows down the object on every frame. The acceleration increases by 0.5 on every frame if we keep the key pressed. We do have a bit of code duplication in our method but it’s fine for the purposes of this demo. update() Let’s put everything together: verletSquare/index.js Here’s a demo of this in action (use the arrow keys): Source code: _game-physx - A small utility for JavaScript game making_github.com raduGaspar/game-physx At this point you might be thinking: Well yes, the complexity is increasing; some of it can’t be avoided and part of it is due to our MVC approach. Aren’t we just adding more complexity to our code? As always, there are improvements to be made here; for starters, the way the scene reference is added on the model is suboptimal, we also have code duplication in our controller and quite a bit of logic in our MVC. We’ll slowly move away from MVC and go towards a Flux architecture as these articles progress but all things considered we did learn more about how movement works in games. Next time we’ll create a class and cover: sprite sheets, sprites, animated sprites and frame rate control. DisplayObject

JavaScript: Do you like games? (part 3)

Note: Updated for Swift 4. For a hack day at work I decided to try my hand at creating a share extension. I discovered that there wasn’t a fully-featured out there, and as a result I had to piece together information (much of it attributed, surprisingly, to the ). tutorial Apple documentation The Goal To save a web page URL as rich content into our app, and allow for configuration of a few options. Initially I thought an was what was needed — but it seems that is better suited for modifying content (such as removing red-eye on a photo with one tap). It seems others, Apple included, are using the share extension to create items instead. extension action This is what we’ll have built by the end: The completed extension As you can see I’ve customized the design a little, and added what’s referred to as a “configuration item” which are cells at the bottom of the sheet; commonly used to select from accounts or other options. It’s used here to select from the user’s existing “Decks” to save to. What you can’t see is it’s also running some JavaScript code to fetch the current URL of the browser, which we send to the server later. We’ll cover all of this ahead! Initial Steps Either create a new project, or open an existing one you’d like to add the extension to. Then hit Under the tab select and press Give it a name; I opted for the simple “ShareExtension”. File > New > Target. iOS Share Extension Next. It will ask if you’d like to activate the scheme. This means when you run the application it will allow you to open straight into Safari or similar to test the extension, as opposed to your main app. We want this — tap . Activate Test what you have so far by running the project as mentioned it gives you options of which app to test from, select and tap Cmd + R — Safari Run. The dialog presented when running an extension. When Safari opens, tap the share icon and your extension name with the placeholder icon should appear in the list. If not, tap and enable it. Tapping on the icon will present the default implementation, which is pretty neat right out of the box. More SLComposeServiceViewController’s Getting the URL The share sheet automatically retrieves the page title and sets it as the body text, but generally you’ll want more than that — whether it be the URL or an image on the page. For this you can have Safari run a JavaSript file to parse the document and retrieve whatever we need. First up, right click on your extensions folder in Xcode and select You’ll find inside of the tab, hit and name the file “GetURL.js”. New File. Empty Other Next You’ll need to edit your extensions file and in “NSExtension” there’s another dictionary called “NSExtensionAttributes” — add a key “NSExtensionJavaScriptPreprocessingFile” with the value of our file just created, “GetURL” (note the lack of extension). Info.plist Also add a dictionary row “NSExtensionActivationRule” which should contain the key “NSExtensionActivationSupportsWebURLWithMaxCount” with the number 1: How your extension’s Info.plist should look when viewed as a property list NSExtensionJavaScriptPreprocessingFile: this lets our app know of a JavaScript file that should be run on execution of the extension. NSExtensionActivationRule: use this dictionary to add which help the system determine what types of content to activate your extension for. Action Extension Keys Paste the following into “GetURL.js”: Coupled with the keys we set above, iOS now will look for an object named “ExtensionPreprocessingJS” to perform at runtime. This is explained in more detail in . Apple’s documentation In order to retrieve the data scraped with the javascript file above, you’ll need to run this block of code within the “ShareViewController.swift” function: viewDidLoad You’ll also need this import for kUTTypePropertyList: MobileCoreServices import Running the extension now should successfully print the URL to the console! Side note: add the following snippet if you’d like to customize the navigation bar as I have (replacing with your own image or just a title). Adding Configuration Cells The boilerplate that came with creating your share extension will have included a method to optionally supply configuration items (the cells in the bottom of the share sheet) override func configurationItems() -> [AnyObject]! { Insert the below snippet, which returns an array of “SLComposeSheetConfigurationItem”: Run your app again and you’ll see a cell at the bottom now. A Model for the Configuration Item Create a basic model called “Deck.swift”, which is used ahead to pass data between view controllers. The TableView In the gif at the beginning, you’ll have noticed when tapping on the configuration cell it pushes to a new view with a tableview. Create a new file that inherits from “UIViewController” named “ShareSelectViewController.swift”. Create a tableview property and add it to the view. I’ve also set the title and title color for this view, and prefer to keep constants like cell identifiers in a struct :) Create a property to store the Deck’s passed in from the original view controller: var userDecks = [Deck]() And conform to the required protocols for the tableview: Back in the“ShareViewController.swift”, create a property to store some dummy data and populate it within viewDidLoad: Lastly, inside the tapHandler for the configuration item we created, create an instance of the and have it push on tap, passing the decks in as well: ShareSelectViewController Run the app. Tapping the configuration cell should push to the tableview with the dummy data. However you’ll notice the configuration cell is still hardcoded to “Deck Title”. To have this update, create a property to store the deck selected and select the first by default: And update the configuration cell inside to use it: configurationItems() deck.value = selectedDeck?.title Run the app again and you’ll see it has updated. A Protocol to Update Selected Deck You’ll need a way to dismiss back to the when a new Deck is tapped, and have it update the UI. A protocol will suffice. Add the following to your ShareViewController ShareSelectViewController: Lastly, conform the to the protocol just made and ensure the delegate for the ShareSelectViewController is set to self: ShareViewController The selected Deck is updated, and the configuration items are reloaded to update the value. Then we pop to go back to the main screen. Run the app and now you should be able to change decks which will update to show the correctly selected deck :) Finishing Up All that’s left is to send the collected information to your server or app to do something with, which you can do inside another boilerplate method: override func didSelectPost() I won’t go into detail about this, but I used an to post to our server. I also replaced the dummy data with real decks by creating an and using a shared to store and retrieve data earlier retrieved within the main iOS app. NSURLSession app group NSUserDefaults let userDefaults = NSUserDefaults(suiteName: "some.group.name") let decks = userDefaults?.objectForKey(“userDecks”) as? NSArray Lastly, you’ll notice my extension is named “Vurb” in the action dialog, and has an icon. You can set an icon by . And to change the name simply change “Display Name” in the project settings for the extension_._ following this SO post That’s everything, if you found this helpful please help other’s find it by recommending. You can view the project in entirety . here

How-to Build an iOS Share Extension in Swift

The Spring Factory

**DUBAI, UAE, July 15th, 2024/CyberNewsWire/--**On May 31, 2024, as a result of the hacking 4502.9 BTC(worth approximately $308M)were stolen from the Japanese exchange Bitcoin.DMM.com. The cybersecurity agency Match Systems conducted the current situation of the case. Japanese cryptocurrency exchange DMM Bitcoin was recently hacked, resulting in the theft of over $300 million dollars in Bitcoins. The hackers were able to access a private key, which allowed them to transfer 4,502.9 bitcoins from the exchange's main wallet. The incident occurred on May 30, 2024, and DMM Bitcoin announced the hack the following day. The reasons for the hack of the exchange are still unclear. The attack could have occurred as a result of compromised private keys. The keys of a hot wallet connected to the Internet could have been compromised either through an internal threat or an external hack, which could have allowed hackers to initiate a transfer of funds. Whether social engineering techniques or malware were used to get exchange employees to sign a transaction authorizing the transfer of funds to their wallets, we have yet to learn. An insider attack scenario cannot be ruled out, in which someone with legitimate access to the system contributed to the hack by giving the hackers the necessary data or initiating the attack. The investigation revealed that the hackers used cryptocurrency mixer JoinMarket to launder the stolen funds. More than 2,000 BTC was sent to addresses associated with JoinMarket, while the remaining 2,500 BTC remained at the hackers' original addresses. The Match Systems team was able to identify the first large withdrawal from the mixer in the amount of 223.38 BTC, as well as more than 50 withdrawals over 10 BTC that may be relevant to this case. The full cycle of money laundering can take months to a year, and Match Systems will continue to monitor the movement of stolen funds, as well as looking into the cause of the attack. About Match Systems Match Systems, is a leading company specializing in AML services, blockchain investigations, and implementation of compliance procedures for cryptocurrency projects around the world. By leveraging advanced technology and expertise in financial crime detection, the company is poised to help organizations to navigate the complex regulatory landscape as well as minimize the risks associated with digital currencies. Contact Joseph Match Systems mediacoverage@matchsystems.com This story was distributed as a release by Cyberwire under HackerNoon’s Business Blogging Program. Learn more about the program here. **DUBAI, UAE, July 15th, 2024/CyberNewsWire/--**On May 31, 2024, as a result of the hacking 4502.9 BTC(worth approximately $308M)were stolen from the Japanese exchange Bitcoin.DMM.com. The cybersecurity agency Match Systems conducted the current situation of the case. Japanese cryptocurrency exchange DMM Bitcoin was recently hacked, resulting in the theft of over $300 million dollars in Bitcoins. The hackers were able to access a private key, which allowed them to transfer 4,502.9 bitcoins from the exchange's main wallet. The incident occurred on May 30, 2024, and DMM Bitcoin announced the hack the following day. The reasons for the hack of the exchange are still unclear. The attack could have occurred as a result of compromised private keys. The keys of a hot wallet connected to the Internet could have been compromised either through an internal threat or an external hack, which could have allowed hackers to initiate a transfer of funds. Whether social engineering techniques or malware were used to get exchange employees to sign a transaction authorizing the transfer of funds to their wallets, we have yet to learn. An insider attack scenario cannot be ruled out, in which someone with legitimate access to the system contributed to the hack by giving the hackers the necessary data or initiating the attack. The investigation revealed that the hackers used cryptocurrency mixer JoinMarket to launder the stolen funds. More than 2,000 BTC was sent to addresses associated with JoinMarket, while the remaining 2,500 BTC remained at the hackers' original addresses. The Match Systems team was able to identify the first large withdrawal from the mixer in the amount of 223.38 BTC, as well as more than 50 withdrawals over 10 BTC that may be relevant to this case. The full cycle of money laundering can take months to a year, and Match Systems will continue to monitor the movement of stolen funds, as well as looking into the cause of the attack. About Match Systems Match Systems , is a leading company specializing in AML services, blockchain investigations, and implementation of compliance procedures for cryptocurrency projects around the world. By leveraging advanced technology and expertise in financial crime detection, the company is poised to help organizations to navigate the complex regulatory landscape as well as minimize the risks associated with digital currencies. Match Systems Match Systems Contact Joseph Match Systems mediacoverage@matchsystems.com This story was distributed as a release by Cyberwire under HackerNoon’s Business Blogging Program. Learn more about the program here. This story was distributed as a release by Cyberwire under HackerNoon’s Business Blogging Program. Learn more about the program here . here here

Match Systems' CEO Andrei Kutin Provides Insight On DMM Bitcoin Breach

“What can the critics do but stare” This was my thought as the news broke of GameStop rallying 110% during yesterday’s trading session."Is this happening again?" I whispered, a stunned laugh escaping my lips. With GameStop’s recent price action, investors around the world are embracing a new reality that a daring meme stock can also take Wall Street by storm. The story of GameStop’s miraculous comeback still continues to captivate the investing audience even though three years have passed since it experienced an unprecedented turn of events that saw it going from doom to boom. And that it took one man’s appetite for the shares of a struggling company to trigger the liquidation of billions of dollars in the stock market is no less amusing. When the demand for the shares of a struggling company on a popular stock exchange such as Wall Street is driven by a group of meme-loving investors banding together to give established investors a run for their money, you have a situation that resembles a rescue mission, and in the phraseology of being concise and self-explanatory, experts define such shares as a meme stock to show that they are of an interesting origin. Although critics acknowledge that investing in meme stocks carries the same level of risks as traditional stocks, for “dumb apes”, a pejorative phrase used to refer to the members of a meme stock community, to liquidate $1 billion on the stock market in one hour can not be less newsworthy. But what is all the more interesting is that these stocks have been holding the line since 2021. I guess this is just history repeating itself or another occasion to teach hedge fund investors a lesson. The first time this happened was in 2021 when a user on the Reddit forum WallStreetBets, Keith Gill, invested $50,000 of his money in GameStop, which was trading at an unattractive price of $4 at the time. Booed and bullied, Gill stayed put, built a silent army of investors, and lo and behold by January 2021, his $50,000 was now worth a staggering $48 million, with the GameStop’s value increasing by 1,915%  and trading at $347.51. This rally took Wall Street investors by surprise and caused a lot of rich investors to lose a lot of money through short selling. To the vast astonishment of WallStreet, it was discovered that a vast army of redditors led by Gill was behind the massive demand for GameStop stock, an event that would later bring him fame. Three Years Later Returning to the social media space three years after leading a resistance against Wall Street's Hedge Funds, Keith Gill is certain he would make headlines across the world as soon as he dropped a tweet. His absence after the event that cost Wall Street investors over $12.5 billion only meant that his return had been very much anticipated. While it is too early to conclude that the meme stock frenzy is back, Gill‘s return might offer a clue into how the market responded to it: short sellers have already lost $1 billion dollars and AMC, another meme stock, has recorded a $33 increase. This is not unexpected. After all, he is a symbol of that very historic sentiment that brought GameStop back from the dead. Sentiments Over Fundamentals A valuable lesson modern-day investors can learn from this experience is that sentiment is a powerful force in the investment landscape, especially in the digital age where information moves at a breakneck speed. It surmises that even in the absence of strong fundamentals, a conscious investing community like that of WallStreetBets can shape the financial landscape. This was true of the prevailing mood at the time engineered by Keith Gill(aka Roaring Kitty). It should be remembered that in 2021, Gill, while known by the moniker DeepF**kingValue, gave an utterance to his feelings about Wall Street firms heavily shorting GameStop stock in a bid to profit from its decline. This predatory short-selling might have enraged Gill greatly, prompting him to weaponize his feelings. In Gill’s first return post on X, we are treated to a diagram of a man sitting awkwardly on a chair. With over 27 million views, 11,000 comments, and 31,000 retweets so far recorded, the impact of this tweet is still a subject of discussion among financial pundits. But in a matter of hours, we have seen the reaction of the stock market in the ongoing short squeeze reminiscent of the 2021 massive financial loss sustained by prominent Wall Street investors. Conclusion The return of meme stocks and the resurgence of GameStop raise intriguing questions about the future of the stock market. While some see it as a fleeting phenomenon, others believe it represents a fundamental shift in power dynamics. Regardless, one thing is certain: the age of information and social media has given retail investors a powerful voice, and their influence on the market cannot be ignored. As the story unfolds, it will be fascinating to see how Wall Street adapts and how regulators respond to this evolving landscape. “What can the critics do but stare” This was my thought as the news broke of GameStop rallying 110% during yesterday’s trading session. "Is this happening again?" I whispered, a stunned laugh escaping my lips. With GameStop’s recent price action, investors around the world are embracing a new reality that a daring meme stock can also take Wall Street by storm. “What can the critics do but stare” "Is this happening again?" The story of GameStop’s miraculous comeback still continues to captivate the investing audience even though three years have passed since it experienced an unprecedented turn of events that saw it going from doom to boom. And that it took one man’s appetite for the shares of a struggling company to trigger the liquidation of billions of dollars in the stock market is no less amusing. When the demand for the shares of a struggling company on a popular stock exchange such as Wall Street is driven by a group of meme-loving investors banding together to give established investors a run for their money, you have a situation that resembles a rescue mission, and in the phraseology of being concise and self-explanatory, experts define such shares as a meme stock to show that they are of an interesting origin. Although critics acknowledge that investing in meme stocks carries the same level of risks as traditional stocks, for “dumb apes”, a pejorative phrase used to refer to the members of a meme stock community, to liquidate $1 billion on the stock market in one hour can not be less newsworthy. But what is all the more interesting is that these stocks have been holding the line since 2021. I guess this is just history repeating itself or another occasion to teach hedge fund investors a lesson. The first time this happened was in 2021 when a user on the Reddit forum WallStreetBets, Keith Gill, invested $50,000 of his money in GameStop, which was trading at an unattractive price of $4 at the time. Booed and bullied, Gill stayed put, built a silent army of investors, and lo and behold by January 2021, his $50,000 was now worth a staggering $48 million, with the GameStop’s value increasing by 1,915%  and trading at $347.51. This rally took Wall Street investors by surprise and caused a lot of rich investors to lose a lot of money through short selling. To the vast astonishment of WallStreet, it was discovered that a vast army of redditors led by Gill was behind the massive demand for GameStop stock, an event that would later bring him fame. Three Years Later Returning to the social media space three years after leading a resistance against Wall Street's Hedge Funds, Keith Gill is certain he would make headlines across the world as soon as he dropped a tweet. His absence after the event that cost Wall Street investors over $12.5 billion only meant that his return had been very much anticipated. While it is too early to conclude that the meme stock frenzy is back, Gill‘s return might offer a clue into how the market responded to it: short sellers have already lost $1 billion dollars and AMC, another meme stock, has recorded a $33 increase. This is not unexpected. After all, he is a symbol of that very historic sentiment that brought GameStop back from the dead. Sentiments Over Fundamentals A valuable lesson modern-day investors can learn from this experience is that sentiment is a powerful force in the investment landscape, especially in the digital age where information moves at a breakneck speed. It surmises that even in the absence of strong fundamentals, a conscious investing community like that of WallStreetBets can shape the financial landscape. This was true of the prevailing mood at the time engineered by Keith Gill(aka Roaring Kitty). It should be remembered that in 2021, Gill, while known by the moniker DeepF**kingValue, gave an utterance to his feelings about Wall Street firms heavily shorting GameStop stock in a bid to profit from its decline. This predatory short-selling might have enraged Gill greatly, prompting him to weaponize his feelings. In Gill’s first return post on X , we are treated to a diagram of a man sitting awkwardly on a chair. With over 27 million views, 11,000 comments, and 31,000 retweets so far recorded, the impact of this tweet is still a subject of discussion among financial pundits. But in a matter of hours, we have seen the reaction of the stock market in the ongoing short squeeze reminiscent of the 2021 massive financial loss sustained by prominent Wall Street investors. Gill’s first return post on X Gill’s first return post on X Conclusion The return of meme stocks and the resurgence of GameStop raise intriguing questions about the future of the stock market. While some see it as a fleeting phenomenon, others believe it represents a fundamental shift in power dynamics. Regardless, one thing is certain: the age of information and social media has given retail investors a powerful voice, and their influence on the market cannot be ignored. As the story unfolds, it will be fascinating to see how Wall Street adapts and how regulators respond to this evolving landscape.

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