6,506 research outputs found

    Sclerotherapy of spider veins

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    Granular discharge rate for submerged hoppers

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    The discharge of spherical grains from a hole in the bottom of a right circular cylinder is measured with the entire system underwater. We find that the discharge rate depends on filling height, in contrast to the well-known case of dry non-cohesive grains. It is further surprising that the rate increases up to about twenty five percent, as the hopper empties and the granular pressure head decreases. For deep filling, where the discharge rate is constant, we measure the behavior as a function of both grain and hole diameters. The discharge rate scale is set by the product of hole area and the terminal falling speed of isolated grains. But there is a small-hole cutoff of about two and half grain diameters, which is larger than the analogous cutoff in the Beverloo equation for dry grains

    A Classical Analogue to the Standard Model, Chapters 4-11: Particle generations and masses; curved spacetimes and gravitation; heavy weak bosons

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    The C∧18\mathbb{C}^{\wedge 18} analogue model contains counterparts to the particle spectrum and interactions of the Standard Model, and has only three tunable parameters. As the structure of this model is highly constrained, predictive relationships between constants may be obtained. In Chapters 4-6, the masses of the tau, the WW and ZZ bosons, and a Higgs-like scalar boson are calculated as functions of α\alpha, mem_e, and mμm_\mu. They are shown to be 1.776867413(43)1.776867413(43) GeV/c2c^2, 80.3587(22)80.3587(22) GeV/c2c^2, 91.1877(35)91.1877(35) GeV/c2c^2, and 125.1261(48)125.1261(48) GeV/c2c^2 respectively, with no free fitting parameters. All are within 0.1 σ0.1\,\sigma of the observed values of 1.77686(12)1.77686(12) GeV/c2c^2, 80.360(16)80.360(16) GeV/c2c^2, 91.1876(21)91.1876(21) GeV/c2c^2, and 125.11(11)125.11(11) GeV/c2c^2 respectively. In Chapter 7 the final ungauged freedom of the C∧18\mathbb{C}^{\wedge 18} model is used to eliminate the right-handed weak interaction, while simultaneously introducing space-time curvature and a gravitational interaction emulating general relativity. The value of Newton's constant is then calculated from α\alpha, mem_e, and mμm_\mu, yielding GN=6.67426(230)×10−11 m3kg−1s−2G_N=6.67426(230)\times 10^{-11}~\mathrm{m}^3\mathrm{kg}^{-1}\mathrm{s}^{-2}, which is in agreement with the observed value of GN=6.67430(15)×10−11 m3kg−1s−2G_N=6.67430(15)\times 10^{-11}~\mathrm{m}^3\mathrm{kg}^{-1}\mathrm{s}^{-2} with tension less than 0.1 σexp0.1\,\sigma_\mathrm{exp}. This persistent consistency with experiment suggests the existence of a unifying relationship between lepton generations, gravitation, and the electroweak mass scale. In the Classical Analogue to the Standard Model this unification arises from an underlying construction from coloured preons, with the low-energy residuals of the preon binding interactions corresponding to the strong nuclear force.Comment: 201 pages, 46 figures. Updated calculation of Higgs boson mass (0.1% correction; Secs. 5:3.3 & 6:4.5). Added some initial discussion of Higgs interactions in CASMIR (Ch. 11

    Cognition as Embodied Morphological Computation

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    Cognitive science is considered to be the study of mind (consciousness and thought) and intelligence in humans. Under such definition variety of unsolved/unsolvable problems appear. This article argues for a broad understanding of cognition based on empirical results from i.a. natural sciences, self-organization, artificial intelligence and artificial life, network science and neuroscience, that apart from the high level mental activities in humans, includes sub-symbolic and sub-conscious processes, such as emotions, recognizes cognition in other living beings as well as extended and distributed/social cognition. The new idea of cognition as complex multiscale phenomenon evolved in living organisms based on bodily structures that process information, linking cognitivists and EEEE (embodied, embedded, enactive, extended) cognition approaches with the idea of morphological computation (info-computational self-organisation) in cognizing agents, emerging in evolution through interactions of a (living/cognizing) agent with the environment

    Aerojet - Attitude Control Engines

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    All the engines were both qualification and acceptance tested at Marquardt s facilities. After we won the Apollo Program contract, we went off and built two vacuum test facilities, which simulated altitude continuous firing for as long as we wanted to run an engine. They would run days and days with the same capability we had on steam ejection. We did all of the testing in both for the qualification and the acceptance test. One of them was a large ball, which was an eighteen-foot diameter sphere, evacuated again with a big steam ejector system that could be used for system testing; that s where we did the Lunar Excursion Module testing. We put the whole cluster in there and tested the entire cluster at the simulated altitude conditions. The lowest altitude we tested at - typically an acceptance test - was 105,000 feet simulated altitude. The big ball - because people were interested in what they called goop formation, which is an unburned hydrazine product migrating to cold surfaces on different parts of spacecraft - was built to address those kinds of issues. We ran long-life tests in a simulated space environment with the entire inside of the test cell around the test article, liquid nitrogen cooled, so it could act as getter for any of the exhaust products. That particular facility could pull down to about 350,000 feet (atmosphere) equivalent altitude, which was pushing pretty close to the thermodynamic triple point of the MMH. It was a good test facility. Those facilities are no longer there. When the guys at Marquardt sold the company to what eventually became part of Aerojet, all those test facilities were cut off at the roots. I think they have a movie studio there at this point. That part of it is truly not recoverable, but it did some excellent high-altitude, space-equivalent testing at the time. Surprisingly, we had very few problems while testing in the San Fernando Valley. In the early 1960s, nobody had ever seen dinitrogen tetroxide (N2O4), so that wasn't too big a deal. We really did only make small, red clouds. In all the hundreds of thousands of tests and probably well over one million firings that I was around that place for, in all that thirty-something years, we had a total of one serious injury associated with rocket engine testing and propellants. Because we were trying to figure out what propellants would really be good, we tried all of the fun stuff like the carbon tetrafluoride, chlorine pentafluoride, and pure fluorine. The materials knowledge wasn't all that great at the time. On one test, the fluorine we had didn't react well with the copper they were using for tubing, and it managed to cause another unscheduled disassembly of the facility. It was very serious. It's like one of those Korean War stories. The technician happened to be walking past the test facility when it decided to blow itself up. A piece of copper tubing pierced one cheek and came out the other. That was the only serious accident in all of the engines handled in all those years. Now, we did have a problem with the EPA later because they figured out what the brown clouds were about. We built a whole bunch of exhaust mitigation scrubbers to take care of engine testing in the daytime. In general, we operated the big shuttle (RCS) engine, the 870- pounder at nominal conditions; they scrubbed the effluents pretty well. If you operated that same 870-pound force engine at a level where you get a lot of excess oxidizer, yeah, there s a brown cloud. But, you know, it doesn't show up well in the dark. They did do some of that. But, that s gone; it was addressed one way or another. RELEASED
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