20,635 research outputs found

    Control of Electrophilicity in Aliphatic Friedel-Crafts Reactions

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    Fiber optics wavelength division multiplexing(components)

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    The long term objectives are to develop optical multiplexers/demultiplexers, different wavelength and modulation stable semiconductor lasers and high data rate transceivers, as well as to test and evaluate fiber optic networks applicable to the Space Station. Progress in each of the above areas is briefly discussed

    Brief state-of-the-art review on optical communications for the NASA ISES workshop

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    The current state of the art of optical communications is briefly reviewed. This review covers NASA programs, DOD and other government agency programs, commercial aerospace programs, and foreign programs. Included is a brief summary of a recent NASA workshop on optical communications. The basic conclusions from all the program reviews is that optical communications is a technology ready to be accepted but needed to be demonstrated. Probably the most advanced and sophisticated optical communications system is the Laser Intersatellite Transmission Experiment (LITE) system developed for flight on the Advanced Communications Technology Satellite (ACTS). Optical communications technology is available for the applications of data communications at data rates in the under 300 MBits/sec for nearly all applications under 2 times GEO distances. Applications for low-earth orbiter (LEO) to ground will allow data rates in the multi-GBits/sec range. Higher data rates are limited by currently available laser power. Phased array lasers offer technology which should eliminate this problem. The major problem of cloud coverage can probably be eliminated by look ahead pointing, multiple ground stations, and knowledge of weather conditions to control the pointing. Most certainly, optical communications offer a new spectral region to relieve the RF bands and very high data communications rates that will be required in less than 10 years to solve the communications problems on Earth

    Workload and stress in driving

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    Comparison of Optimal Control Solutions in a Labor Market Model

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    In this paper a variety of computational optimal control techniques are compared on a complicated nonlinear discrete-time model. We use a labor market model with the objective of trying to obtain an unemployment rate objective, using an active labor market program as a control. In reality the control is constrained as only limited proportion of the unemployment can attend the labor market program. A variety of computational optimal control techniques are applied. The techniques include numerically linearizing the model and using standard linear quadratic optimal control and applying this to the nonlinear model; model based predictive control; and stacking the model over time and using optimisation techniquesLabour market policies; Optimal Control.

    Foreword

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    A toast to the Model Business Corporation Act (MBCA), and especially its forefathers, on its 60th Birthday! Now at age 60, the MBCA is still vibrant, meaningful, and it forms the bedrock for the health of the United States corporate economy

    Pattern avoidance in compositions and multiset permutations

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    We study pattern avoidance by combinatorial objects other than permutations, namely by ordered partitions of an integer and by permutations of a multiset. In the former case we determine the generating function explicitly, for integer compositions of n that avoid a given pattern of length 3 and we show that the answer is the same for all such patterns. We also show that the number of multiset permutations that avoid a given three-letter pattern is the same for all such patterns, thereby extending and refining earlier results of Albert, Aldred et al., and by Atkinson, Walker and Linton. Further, the number of permutations of a multiset S, with a_i copies of i for i = 1, ..., k, that avoid a given permutation pattern in S_3 is a symmetric function of the a_i's, and we will give here a bijective proof of this fact first for the pattern (123), and then for all patterns in S_3 by using a recently discovered bijection of Amy N. Myers.Comment: 8 pages, no figur
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