1,155 research outputs found

    Fluid state amplifier and compensation for the model nv-b1 gimbal actuator final report, 29 jun. 1964 - 29 mar. 1965

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    Fluid amplifier, servovalve, and compensation network for use with pneumatic actuator on J- 2 rocket engine Thrust Vector Control /TVC

    Pneumatic nutator actuator motor Final report

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    Low speed high torque pneumatic nutator actuator motor for manipulating control drums of nuclear rocket reactor

    Perturbation of an Eigen-Value from a Dense Point Spectrum : An Example

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    We study a perturbed Floquet Hamiltonian K+βVK+\beta V depending on a coupling constant β\beta. The spectrum σ(K)\sigma(K) is assumed to be pure point and dense. We pick up an eigen-value, namely 0σ(K)0\in\sigma(K), and show the existence of a function λ(β)\lambda(\beta) defined on IRI\subset\R such that λ(β)σ(K+βV)\lambda(\beta) \in \sigma(K+\beta V) for all βI\beta\in I, 0 is a point of density for the set II, and the Rayleigh-Schr\"odinger perturbation series represents an asymptotic series for the function λ(β)\lambda(\beta). All ideas are developed and demonstrated when treating an explicit example but some of them are expected to have an essentially wider range of application.Comment: Latex, 24 pages, 51

    THE BIOMECHANIST AS EXPERT WITNESS

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    INTRODUCTION There is a critical need for qualified Biomechanists in the areas of civil and criminal litigation. Currently few "true Biomechanists" work in this area. This has resulted in a vacuum of qualified personnel being filled by people who speak to biomechanical issues with little or no education, training, and experience in anatomy, kinesiology, physiology, research methods, statistics and other areas that constitute the discipline of Biomechanics. The result is that legal decisions are made based upon incorrect or inadequate information. We suggest that as professional Biomechanists we may have a responsibility to enter this area or in our absence abdicate our role to less qualified individuals. If we as a discipline do engage this role we will upgrade the quality and truthfulness of at least a portion of the litigation process

    On the energy growth of some periodically driven quantum systems with shrinking gaps in the spectrum

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    We consider quantum Hamiltonians of the form H(t)=H+V(t) where the spectrum of H is semibounded and discrete, and the eigenvalues behave as E_n~n^\alpha, with 0<\alpha<1. In particular, the gaps between successive eigenvalues decay as n^{\alpha-1}. V(t) is supposed to be periodic, bounded, continuously differentiable in the strong sense and such that the matrix entries with respect to the spectral decomposition of H obey the estimate |V(t)_{m,n}|0, p>=1 and \gamma=(1-\alpha)/2. We show that the energy diffusion exponent can be arbitrarily small provided p is sufficiently large and \epsilon is small enough. More precisely, for any initial condition \Psi\in Dom(H^{1/2}), the diffusion of energy is bounded from above as _\Psi(t)=O(t^\sigma) where \sigma=\alpha/(2\ceil{p-1}\gamma-1/2). As an application we consider the Hamiltonian H(t)=|p|^\alpha+\epsilon*v(\theta,t) on L^2(S^1,d\theta) which was discussed earlier in the literature by Howland

    Weakly regular Floquet Hamiltonians with pure point spectrum

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    We study the Floquet Hamiltonian: -i omega d/dt + H + V(t) as depending on the parameter omega. We assume that the spectrum of H is discrete, {h_m (m = 1..infinity)}, with h_m of multiplicity M_m. and that V is an Hermitian operator, 2pi-periodic in t. Let J > 0 and set Omega_0 = [8J/9,9J/8]. Suppose that for some sigma > 0: sum_{m,n such that h_m > h_n} mu_{mn}(h_m - h_n)^(-sigma) < infinity where mu_{mn} = sqrt(min{M_m,M_n)) M_m M_n. We show that in that case there exist a suitable norm to measure the regularity of V, denoted epsilon, and positive constants, epsilon_* & delta_*, such that: if epsilon |Omega_0| - delta_* epsilon and the Floquet Hamiltonian has a pure point spectrum for all omega in Omega_infinity.Comment: 35 pages, Latex with AmsAr
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