35,841 research outputs found

    Deployment/retraction mechanism for solar maximum mission high gain antenna system

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    A mechanism called a deployment/retraction assembly (DRA) which provides not only a stable, but a deployable platform for the high gain antenna system (HGAS) aboard the Solar Maximum Mission (SMM) spacecraft is described. The DRA also has the capability to retract the system upon command

    Broadcasting of three qubit entanglement via local copying and entanglement swapping

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    In this work,We investigate the problem of secretly broadcasting of three-qubit entangled state between two distant partners. The interesting feature of this problem is that starting from two particle entangled state shared between two distant partners we find that the action of local cloner on the qubits and the measurement on the machine state vector generates three-qubit entanglement between them. The broadcasting of entanglement is made secret by sending the measurement result secretly using cryptographic scheme based on orthogonal states. Further we show that this idea can be extended to generate three particle entangled state between three distant partners.Comment: 18 pages, 4 figures, Accepted in Physical Review

    A Measure of Stregth of an Unextendible Product Basis

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    A notion of strength of an unextendible product basis is introduced and a quantitative measure for it is suggested with a view to providing an indirect measure for the bound entanglement of formation of the bound entangled mixed state associated with an unextendible product basis.Comment: 4 pages, Latex, 1 figure, remarks, criticisms welcom

    To stay or go? A study of police officer turnover data and the drivers behind the decision to remain in or leave the Police Service

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    The main aim of this paper was to explore changing police officer turnover patterns within the Metropolitan Police Service (MPS), as well as to gain a broader understanding as to the motivations behind remaining in service or taking the decision to resign voluntarily. A quantitative approach was taken to assist with the understanding and interpretation of turnover data, with the results being interpreted in light of previous literature with an emphasis on the influence of demographic factors. The results indicated that the MPS has seen a slighter higher than average voluntary turnover rate in the last three years compare to other Police Forces across England and Wales. Overall voluntarily turnover has increased, with female turnover significantly higher than male turnover, BME turnover has increased but this is not significantly higher than the average voluntarily turnover rate. The exploration of the motivations behind an officer’s decision making process required a qualitative approach. Nine officers who had voluntary resigned from the police service as well as nine serving officers who had considered resigning but decided to remain were interviewed. The motivating factors leading to dissatisfaction for former and serving officers were broadly the same; pay, pensions and conditions, lack of opportunity, lack of support and increased pressure. However the current research indicates that the decision making process and the way individuals assess the impact of these changes is different for former and serving officers. These differences are potentially linked to an individual’s original motivations for joining the Police Service

    Phase Transitions and Symmetry Breaking in Genetic Algorithms with Crossover

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    In this paper, we consider the role of the crossover operator in genetic algorithms. Specifically, we study optimisation problems that exhibit many local optima and consider how crossover affects the rate at which the population breaks the symmetry of the problem. As an example of such a problem, we consider the subset sum problem. In so doing, we demonstrate a previously unobserved phenomenon, whereby the genetic algorithm with crossover exhibits a critical mutation rate, at which its performance sharply diverges from that of the genetic algorithm without crossover. At this critical mutation rate, the genetic algorithm with crossover exhibits a rapid increase in population diversity. We calculate the details of this phenomenon on a simple instance of the subset sum problem and show that it is a classic phase transition between ordered and disordered populations. Finally, we show that this critical mutation rate corresponds to the transition between the genetic algorithm accelerating or preventing symmetry breaking and that the critical mutation rate represents an optimum in terms of the balance of exploration and exploitation within the algorithm

    User's Guide for a Modular Flutter Analysis Software System (Fast Version 1.0)

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    The use and operation of a group of computer programs to perform a flutter analysis of a single planar wing are described. This system of programs is called FAST for Flutter Analysis System, and consists of five programs. Each program performs certain portions of a flutter analysis and can be run sequentially as a job step or individually. FAST uses natural vibration modes as input data and performs a conventional V-g type of solution. The unsteady aerodynamics programs in FAST are based on the subsonic kernel function lifting-surface theory although other aerodynamic programs can be used. Application of the programs is illustrated by a sample case of a complete flutter calculation that exercises each program

    Curve fitting of aeroelastic transient response data with exponential functions

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    The extraction of frequency, damping, amplitude, and phase information from unforced transient response data is considered. These quantities are obtained from the parameters determined by fitting the digitized time-history data in a least-squares sense with complex exponential functions. The highlights of the method are described, and the results of several test cases are presented. The effects of noise are considered both by using analytical examples with random noise and by estimating the standard deviation of the parameters from maximum-likelihood theory

    Multiplatform Public Service Broadcasting: The Economic and Cultural Role of UK Digital and TV Independents

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    In this report, produced as part of a two-year Arts & Humanities Research Council project (AH-H0185622-2) on ‘multiplatform public service broadcasting’, focusing on factual/specialist factual as a case study, we detail the role independent production companies play in PSB. We set out how PSB informs the production cultures of independent companies, the tensions that are experienced between profit and public service and the impact multiplatform commissioning and production practices have had on the sector
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