2,050 research outputs found

    Distance between vertical asymptotes of solutions of certain nonlinear differential equations

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    AbstractIn [S.B. Eliason, On the distance between vertical asymptotes of solutions of a second-order differential equation, J. Math. Anal. Appl. 35 (1971) 148–156], Eliason asks the question if there are results concerning bounds for the distance between vertical asymptotes of solutions of the second-order differential equation (ry′)′−pyf(y)=0, in the case where the solution y has at least one zero between each consecutive pair of its vertical asymptotes. In this paper, we answer in the affirmative by presenting such results. We also present other related results for some other nonlinear differential equations

    Orbital order out of spin disorder: How to measure the orbital gap

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    The interplay between spin and orbital degrees of freedom in the Mott-Hubbard insulator is studied by considering an orbitally degenerate superexchange model. We argue that orbital order and the orbital excitation gap in this model are generated through the order-from-disorder mechanism known previously from frustrated spin models. We propose that the orbital gap should show up indirectly in the dynamical spin structure factor; it can therefore be measured using the conventional inelastic neutron scattering method

    A numerical investigation of the stability of steady states and critical phenomena for the spherically symmetric Einstein-Vlasov system

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    The stability features of steady states of the spherically symmetric Einstein-Vlasov system are investigated numerically. We find support for the conjecture by Zeldovich and Novikov that the binding energy maximum along a steady state sequence signals the onset of instability, a conjecture which we extend to and confirm for non-isotropic states. The sign of the binding energy of a solution turns out to be relevant for its time evolution in general. We relate the stability properties to the question of universality in critical collapse and find that for Vlasov matter universality does not seem to hold.Comment: 29 pages, 10 figure

    Opportunities for Women ∗

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    Economics, University of Essex, for private circulation to interested readers. They often represent preliminary reports on work in progress and should therefore be neither quoted nor referred to in published work without the written consent of the author. Equilibrium Search and the Impact of Equa

    Fiber Optic Strain Sensor for Planetary Gear Diagnostics

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    This paper presents a new sensing approach for helicopter damage detection in the planetary stage of a helicopter transmission based on a fiber optic strain sensor array. Complete helicopter transmission damage detection has proven itself a difficult task due to the complex geometry of the planetary reduction stage. The crowded and complex nature of the gearbox interior does not allow for attachment of sensors within the rotating frame. Hence, traditional vibration-based diagnostics are instead based on measurements from externally mounted sensors, typically accelerometers, fixed to the gearbox exterior. However, this type of sensor is susceptible to a number of external disturbances that can corrupt the data, leading to false positives or missed detection of potentially catastrophic faults. Fiber optic strain sensors represent an appealing alternative to the accelerometer. Their small size and multiplexibility allows for potentially greater sensing resolution and accuracy, as well as redundancy, when employed as an array of sensors. The work presented in this paper is focused on the detection of gear damage in the planetary stage of a helicopter transmission using a fiber optic strain sensor band. The sensor band includes an array of 13 strain sensors, and is mounted on the ring gear of a Bell Helicopter OH-58C transmission. Data collected from the sensor array is compared to accelerometer data, and the damage detection results are presente

    Alternative approach to b>sγb->s \gamma in the uMSSM

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    The gluino contributions to the C7,8C'_{7,8} Wilson coefficients for b>sγb->s \gamma are calculated within the unconstrained MSSM. New stringent bounds on the δ23RL\delta^{RL}_{23} and δ23RR\delta^{RR}_{23} mass insertion parameters are obtained in the limit in which the SM and SUSY contributions to C7,8C_{7,8} approximately cancel. Such a cancellation can plausibly appear within several classes of SUSY breaking models in which the trilinear couplings exhibit a factorized structure proportional to the Yukawa matrices. Assuming this cancellation takes place, we perform an analysis of the b>sγb->s \gamma decay. We show that in a supersymmetric world such an alternative is reasonable and it is possible to saturate the b>sγb->s \gamma branching ratio and produce a CP asymmetry of up to 20%, from only the gluino contribution to C7,8C'_{7,8} coefficients. Using photon polarization a LR asymmetry can be defined that in principle allows for the C7,8C_{7,8} and C7,8C'_{7,8} contributions to the b>sγb->s \gamma decay to be disentangled. In this scenario no constraints on the ``sign of μ\mu'' can be derived.Comment: LaTeX2e, 23 pages, 7 ps figure, needs package epsfi
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