960 research outputs found

    Aircraft aerodynamic prediction method for V/STOL transition including flow separation

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    A numerical procedure was developed for the aerodynamic force and moment analysis of V/STOL aircraft operating in the transition regime between hover and conventional forward flight. The trajectories, cross sectional area variations, and mass entrainment rates of the jets are calculated by the Adler-Baron Jet-in-Crossflow Program. The inviscid effects of the interaction between the jets and airframe on the aerodynamic properties are determined by use of the MCAIR 3-D Subsonic properties are determined by use of the MCAIR 3-D Subsonic Potential Flow Program, a surface panel method. In addition, the MCAIR 3-D Geometry influence Coefficient Program is used to calculate a matrix of partial derivatives that represent the rate of change of the inviscid aerodynamic properties with respect to arbitrary changes in the effective wing shape

    A study of beryllium and beryllium-lithium complexes in single crystal silicon

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    When beryllium is thermally diffused into silicon, it gives rise to acceptor levels 191 MeV and 145 meV above the valence band. Quenching and annealing studies indicate that the 145-MeV level is due to a more complex beryllium configuration than the 191-MeV level. When lithium is thermally diffused into a beryllium-doped silicon sample, it produces two acceptor levels at 106 MeV and 81 MeV. Quenching and annealing studies indicate that these levels are due to lithium forming a complex with the defects responsible for the 191-MeV and 145-MeV beryllium levels, respectively. Electrical measurements imply that the lithium impurity ions are physically close to the beryllium impurity atoms. The ground state of the 106-MeV beryllium level is split into two levels, presumably by internal strains. Tentative models are proposed

    [Review]

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    Binomial Ideals and Congruences on Nn

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    Producción CientíficaA congruence on Nn is an equivalence relation on Nn that is compatible with the additive structure. If k is a field, and I is a binomial ideal in k[X1,…,Xn] (that is, an ideal generated by polynomials with at most two terms), then I induces a congruence on Nn by declaring u and v to be equivalent if there is a linear combination with nonzero coefficients of Xu and Xv that belongs to I. While every congruence on Nn arises this way, this is not a one-to-one correspondence, as many binomial ideals may induce the same congruence. Nevertheless, the link between a binomial ideal and its corresponding congruence is strong, and one may think of congruences as the underlying combinatorial structures of binomial ideals. In the current literature, the theories of binomial ideals and congruences on Nn are developed separately. The aim of this survey paper is to provide a detailed parallel exposition, that provides algebraic intuition for the combinatorial analysis of congruences. For the elaboration of this survey paper, we followed mainly (Kahle and Miller Algebra Number Theory 8(6):1297–1364, 2014) with an eye on Eisenbud and Sturmfels (Duke Math J 84(1):1–45, 1996) and Ojeda and Piedra Sánchez (J Symbolic Comput 30(4):383–400, 2000).National Science Foundation (grant DMS-1500832)Ministerio de Economía, Industria y Competitividad (project MTM2015-65764-C3-1)Junta de Extremadura (grupo de investigación FQM-024

    1838-05-02 Extradition Request From Georgia For Philbrook and Kellerun

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    https://digitalmaine.com/atticus_docs/1006/thumbnail.jp

    Integral closure of rings of integer-valued polynomials on algebras

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    Let DD be an integrally closed domain with quotient field KK. Let AA be a torsion-free DD-algebra that is finitely generated as a DD-module. For every aa in AA we consider its minimal polynomial μa(X)D[X]\mu_a(X)\in D[X], i.e. the monic polynomial of least degree such that μa(a)=0\mu_a(a)=0. The ring IntK(A){\rm Int}_K(A) consists of polynomials in K[X]K[X] that send elements of AA back to AA under evaluation. If DD has finite residue rings, we show that the integral closure of IntK(A){\rm Int}_K(A) is the ring of polynomials in K[X]K[X] which map the roots in an algebraic closure of KK of all the μa(X)\mu_a(X), aAa\in A, into elements that are integral over DD. The result is obtained by identifying AA with a DD-subalgebra of the matrix algebra Mn(K)M_n(K) for some nn and then considering polynomials which map a matrix to a matrix integral over DD. We also obtain information about polynomially dense subsets of these rings of polynomials.Comment: Keywords: Integer-valued polynomial, matrix, triangular matrix, integral closure, pullback, polynomially dense set. accepted for publication in the volume "Commutative rings, integer-valued polynomials and polynomial functions", M. Fontana, S. Frisch and S. Glaz (editors), Springer 201

    Microstructure and velocity of field-driven solid-on-solid interfaces moving under stochastic dynamics with local energy barriers

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    We study the microscopic structure and the stationary propagation velocity of (1+1)-dimensional solid-on-solid interfaces in an Ising lattice-gas model, which are driven far from equilibrium by an applied force, such as a magnetic field or a difference in (electro)chemical potential. We use an analytic nonlinear-response approximation [P.A. Rikvold and M. Kolesik, J. Stat. Phys. 100, 377 (2000)] together with kinetic Monte Carlo simulations. Here we consider interfaces that move under Arrhenius dynamics, which include a microscopic energy barrier between the allowed Ising/lattice-gas states. Two different dynamics are studied: the standard one-step dynamic (OSD) [H.C. Kang and W. Weinberg, J. Chem. Phys. 90, 2824 (1992)] and the two-step transition-dynamics approximation (TDA) [T. Ala-Nissila, J. Kjoll, and S.C. Ying, Phys. Rev. B 46, 846 (1992)]. In the OSD the effects of the applied force and the interaction energies in the model factorize in the transition rates (a soft dynamic), while in the TDA such factorization is not possible (a hard dynamic). In full agreement with previous general theoretical results we find that the local interface width under the TDA increases dramatically with the applied force. In contrast, the interface structure with the OSD is only weakly influenced by the force, in qualitative agreement with the theoretical expectations. Results are also obtained for the force-dependence and anisotropy of the interface velocity, which also show differences in good agreement with the theoretical expectations for the differences between soft and hard dynamics. Our results confirm that different stochastic interface dynamics that all obey detailed balance and the same conservation laws nevertheless can lead to radically different interface responses to an applied force.Comment: 18 pages RevTex. Minor revisions. Phys. Rev. B, in pres

    TRUNK AND UPPER EXTREMITY KINEMATICS OF THE OFFSIDE FOREHAND POLO SWING IN PROFESSIONAL POLO ATHLETES

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    The purpose of this study was to examine trunk (flexion, lateral flexion, rotation) and upper extremity (shoulder horizontal abduction, elevation, and elbow flexion) kinematics of the offside forehand polo swing between professional male and female polo athletes. Kinematic data were collected while participants performed the offside forehand polo swing on a stationary wooden horse. The polo swing was analyzed at three events: take away (TA), top of back swing (TOB) and ball contact (BC). Results revealed significant differences in trunk and upper extremity kinematics between the male and female professional polo athlete. Further investigation into these mechanical differences, along with the influence of live play and performance variables are necessitated to understand mechanics for the most powerful swin
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