1,593 research outputs found

    Determination of wind tunnel constraint effects by a unified pressure signature method. Part 1: Applications to winged configurations

    Get PDF
    A new, fast, non-iterative version of the "Wall Pressure Signature Method" is described and used to determine blockage and angle-of-attack wind tunnel corrections for highly-powered jet-flap models. The correction method is complemented by the application of tangential blowing at the tunnel floor to suppress flow breakdown there, using feedback from measured floor pressures. This tangential blowing technique was substantiated by subsequent flow investigations using an LV. The basic tests on an unswept, knee-blown, jet flapped wing were supplemented to include the effects of slat-removal, sweep and the addition of unflapped tips. C sub mu values were varied from 0 to 10 free-air C sub l's in excess of 18 were measured in some cases. Application of the new methods yielded corrected data which agreed with corresponding large tunnel "free air" resuls to within the limits of experimental accuracy in almost all cases. A program listing is provided, with sample cases

    Determination of wind tunnel constraint effects by a unified pressure signature method. Part 2: Application to jet-in-crossflow

    Get PDF
    The development of an improved jet-in-crossflow model for estimating wind tunnel blockage and angle-of-attack interference is described. Experiments showed that the simpler existing models fall seriously short of representing far-field flows properly. A new, vortex-source-doublet (VSD) model was therefore developed which employs curved trajectories and experimentally-based singularity strengths. The new model is consistent with existing and new experimental data and it predicts tunnel wall (i.e. far-field) pressures properly. It is implemented as a preprocessor to the wall-pressure-signature-based tunnel interference predictor. The supporting experiments and theoretical studies revealed some new results. Comparative flow field measurements with 1-inch "free-air" and 3-inch impinging jets showed that vortex penetration into the flow, in diameters, was almost unaltered until 'hard' impingement occurred. In modeling impinging cases, a 'plume redirection' term was introduced which is apparently absent in previous models. The effects of this term were found to be very significant

    Synthesis of size-controlled Bi particles by electrochemical deposition

    Get PDF
    Small sized bismuth particles are prepared by an electrochemical method using a triple voltage pulse technique. The bath composition and electrochemical parameters are optimized to yield monodisperse particles. The particles have been characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, UV-visible spectroscopy and X-ray diffraction technique. The particles, as deposited, are highly crystalline in nature and the particle size and shape get tuned depending on the conditions of deposition

    Privacy and Truthful Equilibrium Selection for Aggregative Games

    Full text link
    We study a very general class of games --- multi-dimensional aggregative games --- which in particular generalize both anonymous games and weighted congestion games. For any such game that is also large, we solve the equilibrium selection problem in a strong sense. In particular, we give an efficient weak mediator: a mechanism which has only the power to listen to reported types and provide non-binding suggested actions, such that (a) it is an asymptotic Nash equilibrium for every player to truthfully report their type to the mediator, and then follow its suggested action; and (b) that when players do so, they end up coordinating on a particular asymptotic pure strategy Nash equilibrium of the induced complete information game. In fact, truthful reporting is an ex-post Nash equilibrium of the mediated game, so our solution applies even in settings of incomplete information, and even when player types are arbitrary or worst-case (i.e. not drawn from a common prior). We achieve this by giving an efficient differentially private algorithm for computing a Nash equilibrium in such games. The rates of convergence to equilibrium in all of our results are inverse polynomial in the number of players nn. We also apply our main results to a multi-dimensional market game. Our results can be viewed as giving, for a rich class of games, a more robust version of the Revelation Principle, in that we work with weaker informational assumptions (no common prior), yet provide a stronger solution concept (ex-post Nash versus Bayes Nash equilibrium). In comparison to previous work, our main conceptual contribution is showing that weak mediators are a game theoretic object that exist in a wide variety of games -- previously, they were only known to exist in traffic routing games

    Decompositions of some classes of regular graphs into cycles and paths of length eight

    Full text link
    Let CkC_{k} (resp. PkP_{k}) denote the cycle (resp. path) of length kk. In this paper, we examine the necessary and sufficient conditions for the existence of a (8;p,q)(8; p, q)-decomposition of tensor product and wreath product of complete graphs

    Magneto-optics of massive Dirac fermions in bulk Bi2Se3

    Full text link
    We report on magneto-optical studies of Bi2Se3, a representative member of the 3D topological insulator family. Its electronic states in bulk are shown to be well described by a simple Dirac-type Hamiltonian for massive particles with only two parameters: the fundamental bandgap and the band velocity. In a magnetic field, this model implies a unique property - spin splitting equal to twice the cyclotron energy: Es = 2Ec. This explains the extensive magneto-transport studies concluding a fortuitous degeneracy of the spin and orbital split Landau levels in this material. The Es = 2Ec match differentiates the massive Dirac electrons in bulk Bi2Se3 from those in quantum electrodynamics, for which Es = Ec always holds.Comment: 5 pages, 3 figures and Supplementary materials, to be published in Physical Review Letter

    A Component-oriented Framework for Autonomous Agents

    Get PDF
    The design of a complex system warrants a compositional methodology, i.e., composing simple components to obtain a larger system that exhibits their collective behavior in a meaningful way. We propose an automaton-based paradigm for compositional design of such systems where an action is accompanied by one or more preferences. At run-time, these preferences provide a natural fallback mechanism for the component, while at design-time they can be used to reason about the behavior of the component in an uncertain physical world. Using structures that tell us how to compose preferences and actions, we can compose formal representations of individual components or agents to obtain a representation of the composed system. We extend Linear Temporal Logic with two unary connectives that reflect the compositional structure of the actions, and show how it can be used to diagnose undesired behavior by tracing the falsification of a specification back to one or more culpable components

    Moisture management finish on woven fabrics

    Get PDF
    Moisture management behaviour of four different woven fabrics, such as cotton, polyester/cotton blend, microdenierpolyester and nylon, has been studied. A wetting agent of ethoxylated alcohol blend and moisture management finishingagents, such as amino silicone polyether copolymer and hydrophilic polymer, have been prepared and used. Moisturemanagement finishes with wetting agent and without wetting agent are imparted onto woven fabrics. The effect of moisturemanagement finishing process parameters on the comfort properties of woven fabrics has been studied. The optimization ofcomfort level by varying the moisture management finishing process parameters in order to achieve suitability for makingsports wear is done. It is found that the type of fibre and linear density of yarn affect the comfort properties of woven fabricswhich include wicking, wetting, water absorbency and moisture vapour transmission characteristics. Based on the testresults, microdenier polyester fabrics and cotton fabrics exhibit good wicking, wetting and water absorbency characteristicsthan the polyester/cotton blend and nylon. It is found that the combination of ethoxylated alcohol (wetting agent) and therecipe containing amino silicone polyether copolymer and hydrophilic polymer in the ratio of 1:2 with pH of 5.5 at 600-700 Ctemperature is the optimum finishing process than the other two combinations so as to attain better comfort propertiesfor sportswear

    Moisture management finish on woven fabrics

    Get PDF
    486-491Moisture management behaviour of four different woven fabrics, such as cotton, polyester/cotton blend, microdenier polyester and nylon, has been studied. A wetting agent of ethoxylated alcohol blend and moisture management finishing agents, such as amino silicone polyether copolymer and hydrophilic polymer, have been prepared and used. Moisture management finishes with wetting agent and without wetting agent are imparted onto woven fabrics. The effect of moisture management finishing process parameters on the comfort properties of woven fabrics has been studied. The optimization of comfort level by varying the moisture management finishing process parameters in order to achieve suitability for making sports wear is done. It is found that the type of fibre and linear density of yarn affect the comfort properties of woven fabrics which include wicking, wetting, water absorbency and moisture vapour transmission characteristics. Based on the test results, microdenier polyester fabrics and cotton fabrics exhibit good wicking, wetting and water absorbency characteristics than the polyester/cotton blend and nylon. It is found that the combination of ethoxylated alcohol (wetting agent) and the recipe containing amino silicone polyether copolymer and hydrophilic polymer in the ratio of 1:2 with pH of 5.5 at 600-700 C temperature is the optimum finishing process than the other two combinations so as to attain better comfort properties for sportswear
    corecore