16,725 research outputs found

    BCAUS Project description and consideration of separation of data and control

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    The commonly stated truths that data may be segregated from program control in generic expert system shells and that such tools support straightforward knowledge representation were examined. The ideal of separation of data from program control in expert systems is difficult to realize for a variety of reasons. One approach to achieving this goal is to integrate hybrid collections of specialized shells and tools instead of producing custom systems built with a single all purpose expert system tool. Aspects of these issues are examined in the context of a specific diagnostic expert system application, the Backup Control Mode Analysis and Utility System (BCAUS), being developed for the Gamma Ray Observatory (GRO) spacecraft. The project and the knowledge gained in working on the project are described

    Attitude analysis of the Earth Radiation Budget Satellite (ERBS) yaw turn anomaly

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    The July 2 Earth Radiation Budget Satellite (ERBS) hydrazine thruster-controlled yaw inversion maneuver resulted in a 2.1 deg/sec attitude spin. This mode continued for 150 minutes until the spacecraft was inertially despun using the hydrazine thrusters. The spacecraft remained in a low-rate Y-axis spin of .06 deg/sec for 3 hours until the B-DOT control mode was activated. After 5 hours in this mode, the spacecraft Y-axis was aligned to the orbit normal, and the spacecraft was commanded to the mission mode of attitude control. This work presents the experience of real-time attitude determination support following analysis using the playback telemetry tape recorded for 7 hours from the start of the attitude control anomaly

    Golan v. Holder: Copyright in the Image of the First Amendment

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    Does copyright violate the First Amendment? Professor Melville Nimmer asked this question forty years ago, and then answered it by concluding that copyright itself is affirmatively speech protective. Despite ample reason to doubt Nimmer’s response, the Supreme Court has avoided an independent, thoughtful, plenary review of the question. Copyright has come to enjoy an all-but-categorical immunity to First Amendment constraints. Now, however, the Court faces a new challenge to its back-of-the-hand treatment of this vital conflict. In Golan v. Holder the Tenth Circuit considered legislation (enacted pursuant to the Berne Convention and TRIPS) “restoring” copyright protection to millions of foreign works previously thought to belong to the public domain. The Tenth Circuit upheld the legislation, but not without noting that it appeared to raise important First Amendment concerns. The Supreme Court granted certiorari. This article addresses the issues in the Golan case, literally on the eve of oral argument before the Court. This article first considers the Copyright and Treaty Clauses, and then addresses the relationship between copyright and the First Amendment. The discussion endorses an understanding of that relationship in which the Amendment is newly seen as paramount, and copyright is newly seen in the image of the Amendment

    Energy Spectrum Evolution of a Diffuse Field in Elastic Body Caused by Weak Nonlinearity

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    We study the evolution of diffuse elastodynamic spectral energy density under the influence of weak nonlinearity. It is shown that the rate of change of this quantity is given by a convolution of the linear energy at two frequencies. Quantitative estimates are given for sample aluminum and fused silica blocks of experimental interest.Comment: 9 pages, 3 figures; revised for better presentatio

    Quasi Two-dimensional Transfer of Elastic Waves

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    A theory for multiple scattering of elastic waves is presented in a random medium bounded by two ideal free surfaces, whose horizontal size is infinite and whose transverse size is smaller than the mean free path of the waves. This geometry is relevant for seismic wave propagation in the Earth crust. We derive a time-dependent, quasi-2D radiative transfer equation, that describes the coupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and Lamb waves). Expressions are found that relate the small-scale fluctuations to the life time of the modes and to their coupling rates. We discuss a diffusion approximation that simplifies the mathematics of this model significantly, and which should apply at large lapse times. Finally, coherent backscattering is studied within the quasi-2D radiative transfer equation for different source and detection configurations.Comment: REVTeX, 36 pages with 10 figures. Submitted to Phys. Rev.

    A computationally efficacious free-energy functional for studies of inhomogeneous liquid water

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    We present an accurate equation of state for water based on a simple microscopic Hamiltonian, with only four parameters that are well-constrained by bulk experimental data. With one additional parameter for the range of interaction, this model yields a computationally efficient free-energy functional for inhomogeneous water which captures short-ranged correlations, cavitation energies and, with suitable long-range corrections, the non-linear dielectric response of water, making it an excellent candidate for studies of mesoscale water and for use in ab initio solvation methods.Comment: 6 pages, 5 figure

    Effect of growth regulators and heat on germination of Tokay grape seeds

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    Immersing seeds of 'Tokay' for 24 hours in water ranging from 27 ° to 54 °C failed to terminate rest. KGA3 terminated rest in 50% of the seeds, ancl morphactin at 100 ppm and ethephon at 5,000 ppm resulted in some enhancement of germination. However, SADH, CCC, and ABA treatments were not effective. KGA3 at 1 ppm caused 33% germination of scarified resting seeds. SADH increased the germination rate of nonresting seeds, but ABA, BOA, CCC, ethyl alcohol, and sulphuric acid clecreased the rate.Der Einfluß von Wachstumsregulatoren und Wärmebehandlung auf die Keimungvon Samen der Rebsorte TokaySamen der Rebsorte „Tokay", die 24 Stunden in Wasser mit Temperaturen von 27 ° bis 54 °C getaucht worden waren, beendeten die Dormanz nicht. KGA3 hob die Dormanz bei 50% der Samen auf, während Behandlung mit 100 ppm Morphaktin oder mit 5000 ppm Ethephon die Keimung erhöhten. Die Anwendung von SADH, CCC und ABA war jedoch wirkungslos. 1 ppm KGA3 verursachte bei angeritzten dormanten Samen eine Keimung von 33%. SADH steigerte die Keimungsrate der nichtruhenden Samen, während ABA, BOA, CCC, Äthylalkohol und Schwefelsäure die Keimungsrate herabsetzten

    Experiments with Infinite-Horizon, Policy-Gradient Estimation

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    In this paper, we present algorithms that perform gradient ascent of the average reward in a partially observable Markov decision process (POMDP). These algorithms are based on GPOMDP, an algorithm introduced in a companion paper (Baxter and Bartlett, this volume), which computes biased estimates of the performance gradient in POMDPs. The algorithm's chief advantages are that it uses only one free parameter beta, which has a natural interpretation in terms of bias-variance trade-off, it requires no knowledge of the underlying state, and it can be applied to infinite state, control and observation spaces. We show how the gradient estimates produced by GPOMDP can be used to perform gradient ascent, both with a traditional stochastic-gradient algorithm, and with an algorithm based on conjugate-gradients that utilizes gradient information to bracket maxima in line searches. Experimental results are presented illustrating both the theoretical results of (Baxter and Bartlett, this volume) on a toy problem, and practical aspects of the algorithms on a number of more realistic problems
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