76,250 research outputs found

    Energy absorbing system for mechanical impacts

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    System is described based on use of arrangement of crushable hollow spheres bonded together in layers of progressively different diameter, with largest diameter spheres positioned to receive impact forces initially. System is particularly useful for delivery of payloads by air-drop techniques

    Shuttle car loading system

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    A system is described for loading newly mined material such as coal, into a shuttle car, at a location near the mine face where there is only a limited height available for a loading system. The system includes a storage bin having several telescoping bin sections and a shuttle car having a bottom wall that can move under the bin. With the bin in an extended position and filled with coal the bin sections can be telescoped to allow the coal to drop out of the bin sections and into the shuttle car, to quickly load the car. The bin sections can then be extended, so they can be slowly filled with more while waiting another shuttle car

    High temperature underground thermal energy storage system for solar energy

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    The activities feasibility of high temperature underground thermal storage of energy was investigated. Results indicate that salt cavern storage of hot oil is both technically and economically feasible as a method of storing huge quantities of heat at relatively low cost. One particular system identified utilizes a gravel filled cavern leached within a salt dome. Thermal losses are shown to be less than one percent of cyclically transferred heat. A system like this having a 40 MW sub t transfer rate capability and over eight hours of storage capacity is shown to cost about $13.50 per KWh sub t

    Intersection of race and religion for youth in foster care: examining policy and practice

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    Religion and race are primary forces affecting both individuals' identities and social relations. Consequently, their impacts on child welfare systems, and the clients of the system, are important to understand. In addition to protections against discrimination on the basis of religion and race, positive affirmations and connection to relevant communities are also needed to achieve client well-being. This analysis examines both historical and contemporary approaches to addressing religion and race in child welfare policy and practice, with a particular focus on adolescent youth. Our primary focus is on Blacks and Christians because these groups have received predominant attention in the literature. We argue that because racial/ethnic and religious identity development are critical to adolescent well-being, race and religion must receive explicit and consistent attention in child welfare practice. Moreover, the importance of religion has often been overlooked, particularly in its intersection with race. Quality practice needs more explicit attention to religion, but this also raises cautions in the current political environment.Accepted manuscrip

    Constructing graphs with no immersion of large complete graphs

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    In 1989, Lescure and Meyniel proved, for d=5,6d=5, 6, that every dd-chromatic graph contains an immersion of KdK_d, and in 2003 Abu-Khzam and Langston conjectured that this holds for all dd. In 2010, DeVos, Kawarabayashi, Mohar, and Okamura proved this conjecture for d=7d = 7. In each proof, the dd-chromatic assumption was not fully utilized, as the proofs only use the fact that a dd-critical graph has minimum degree at least d1d - 1. DeVos, Dvo\v{r}\'ak, Fox, McDonald, Mohar, and Scheide show the stronger conjecture that a graph with minimum degree d1d-1 has an immersion of KdK_d fails for d=10d=10 and d12d\geq 12 with a finite number of examples for each value of dd, and small chromatic number relative to dd, but it is shown that a minimum degree of 200d200d does guarantee an immersion of KdK_d. In this paper we show that the stronger conjecture is false for d=8,9,11d=8,9,11 and give infinite families of examples with minimum degree d1d-1 and chromatic number d3d-3 or d2d-2 that do not contain an immersion of KdK_d. Our examples can be up to (d2)(d-2)-edge-connected. We show, using Haj\'os' Construction, that there is an infinite class of non-(d1)(d-1)-colorable graphs that contain an immersion of KdK_d. We conclude with some open questions, and the conjecture that a graph GG with minimum degree d1d - 1 and more than V(G)1+m(d+1)\frac{|V(G)|}{1+m(d+1)} vertices of degree at least mdmd has an immersion of KdK_d

    System for slicing silicon wafers

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    An improved system is described which has at least one endless band saw blade that is characterized by a continuously regenerated cutting edge and is unidirectionally driven along a pair of courses extended in mutual parallelism through a cutting station located near the midportion of the courses. The blade is supported at the cutting station by pairs of guides continuously rotated through less than 360 deg of angular displacement during each cutting operation in order to continuously regenerate the blade supporting surfaces of the guide. Blade wobble is thus substantially eliminated

    NLO corrections in MC event generator for angular distribution of Drell-Yan lepton pair production

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    Using a subtraction method, we derive the formulae suitable for use in Monte-Carlo event generators to give the angular distribution for the gluon-quark induced NLO corrections in Drell-Yan lepton pair production. We also give the corresponding helicity density matrix for W and Z boson production.Comment: 14 pages, 2 figure

    Nonlinear-damped Duffing oscillators having finite time dynamics

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    A class of modified Duffing oscillator differential equations, having nonlinear damping forces, are shown to have finite time dynamics, i.e., the solutions oscillate with only a finite number of cycles, and, thereafter, the motion is zero. The relevance of this feature is briefly discussed in relationship to the mathematical modeling, analysis, and estimation of parameters for the vibrations of carbon nano-tubes and graphene sheets, and macroscopic beams and plates.Comment: 15 page

    Charles M. Breder, Jr.: Hypothetical considerations, 1931-1937

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    Charles M. Breder Jr. “hypothesis” diary is a deviation from the field diaries that form part of the Breder collection housed at the Arthur Vining Davis Library, Mote Marine Laboratory. There are no notes or observations from specific scientific expeditions in the document. Instead, the contents provide an insight into the early meticulous scientific thoughts of this biologist, and how he examines and develops these ideas. It is apparent that among Dr. Breder’s passions was his continual search for knowledge about questions that still besieged many scientists. Topics discussed include symmetry, origin of the atmosphere, origin of life, mechanical analogies of organisms, aquaria as an organism, astrobiology, entropy, evolution of species, and other topics. The diary was transcribed as part of the Coastal Estuarine Data/Document Rescue and Archeology effort for South Florida. (PDF contains 33 pages
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