25,265 research outputs found

    A New Method to Improve the Sensitivity of Leak Detection in Self-Contained Fluid-filled Cables

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    A method of real-time detection of leaks for self-contained fluid-filled cables without taking them out of service has been assessed and a novel machine learning technique, i.e. support vector regression (SVR) analysis has been investigated to improve the detection sensitivity of the self-contained fluid-filled (FF) cable leaks. The condition of a 400 kV underground FF cable route within the National Grid transmission network has been monitored by Drallim pressure, temperature and load current measurement system. These three measured variables are used as parameters to describe the condition of the cable system. In the regression analysis the temperature and load current of the cable circuit are used as independent variables and the pressure within cables is the dependent variable to be predicted. As a supervised learning algorithm, the SVR requires data with known attributes as training samples in the learning process and can be used to identify unknown data or predict future trends. The load current is an independent variable to the fluid-filled system itself. The temperature, namely the tank temperature is determined by both the load current and the weather condition i.e. ambient temperature. The pressure is directly relevant to the temperature and therefore also correlated to the load current. The Gaussian-RBF kernel has been used in this investigation as it has a good performance in general application. The SVR algorithm was trained using 4 days data, as shown in Figure 1, and the optimized SVR is used to predict the pressure using the given load current and temperature information

    Phase-space analysis of bosonic spontaneous emission

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    We present phase-space techniques for the modelling of spontaneous emission in two-level bosonic atoms. The positive-P representation is shown to give a full and complete description and can be further developed to give exact treatments of the interaction of degenerate bosons with the electromagnetic field in a given experimental situation. The Wigner representation, even when truncated at second order, is shown to need a doubling of the phase-space to allow for a positive-definite diffusion matrix in the appropriate Fokker-Planck equation and still fails to agree with the full quantum results of the positive-P representation. We show that quantum statistics and correlations between the ground and excited states affect the dynamics of the emission process, so that it is in general non-exponential.Comment: 16 pages, 6 figure

    Leading, Learning, and Leadership Support

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    Offers a framework for improving learning-focused leadership through the use of data and evidence, reallocation of resources, redefined roles and responsibilities, assessment of leadership performance, better governance, and a focus on high schools

    Eigenspace techniques for active flutter suppression

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    The use of eigenspace techniques for the design of an active flutter suppression system for a hypothetical research drone is discussed. One leading edge and two trailing edge aerodynamic control surfaces and four sensors (accelerometers) are available for each wing. Full state control laws are designed by selecting feedback gains which place closed loop eigenvalues and shape closed loop eigenvectors so as to stabilize wing flutter and reduce gust loads at the wing root while yielding accepatable robustness and satisfying constrains on rms control surface activity. These controllers are realized by state estimators designed using an eigenvalue placement/eigenvector shaping technique which results in recovery of the full state loop transfer characteristics. The resulting feedback compensators are shown to perform almost as well as the full state designs. They also exhibit acceptable performance in situations in which the failure of an actuator is simulated

    The Impact of "Deregulation" on Regulator Behavior: An Empirical Analysis of the Telecommunications Act of 1996

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    This paper examines how regulators set local prices in response to the changes brought on by the Telecommunications Act of 1996 (“Telecom Act”). We are particularly interested in the extent to which state regulators set prices that promoted efficiency or were influenced by private-interest groups who had secured rents under a regime of regulated monopoly. Using regional Bell operating company (RBOC) data, our empirical results indicate that private interests continue to influence the structure of retail and wholesale prices, although their influence appears to be waning. We find that changes to the regulatory structure, as measured by federal approval of RBOC Section 271 applications that open up markets to competition and universal service subsidies, resulted in a re-balancing of retail prices and lower overall price levels.competition, political contributions, private interest, public interest, regulation, telecommunications, universal service

    Persistent current formation in a high-temperature Bose-Einstein condensate: an experimental test for c-field theory

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    Experimental stirring of a toroidally trapped Bose-Einstein condensate at high temperature generates a disordered array of quantum vortices that decays via thermal dissipation to form a macroscopic persistent current [T. W. Neely em et al. arXiv:1204.1102 (2012)]. We perform 3D numerical simulations of the experimental sequence within the Stochastic Projected Gross-Pitaevskii equation using ab initio determined reservoir parameters. We find that both damping and noise are essential for describing the dynamics of the high-temperature Bose field. The theory gives a quantitative account of the formation of a persistent current, with no fitted parameters.Comment: v2: 7 pages, 3 figures, new experimental data and numerical simulation

    Estimation and optimal designing under latent variable models for paired comparisons studies via a multiplicative algorithm

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    We consider:<BR/> 1. The problem of estimating the parameters of latent variable models such as the Bradley Terry or Thurstone Model by the method of maximum likelihood, given data from a paired comparisons experiment. The parameters of these models can be taken to be weights which are positive and sum to one;<BR/> 2. The problem of determining approximate locally optimal designs for good estimation of these parameters; i.e of determining optimal design weights which are also positive and sum to one
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