5,533 research outputs found

    Electrodynamic Radiation Reaction and General Relativity

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    We argue that the well-known problem of the instabilities associated with the self-forces (radiation reaction forces) in classical electrodynamics are possibly stabilized by the introduction of gravitational forces via general relativity

    Superdiffusion of massive particles induced by multi-scale velocity fields

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    We study drag-induced diffusion of massive particles in scale-free velocity fields, where superdiffusive behavior emerges due to the scale-free size distribution of the vortices of the underlying velocity field. The results show qualitative resemblance to what is observed in fluid systems, namely the diffusive exponent for the mean square separation of pairs of particles and the preferential concentration of the particles, both as a function of the response time.Comment: 5 pages, 5 figures. Accepted for publication in EP

    Nitriding model for zirconium based fuel cladding in severe accident codes

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    A model has been developed to describe the nitriding of partially oxidized zirconium based cladding during an air ingress sequence when the reaction has become starved of oxidant (oxygen and/or steam), and the subsequent re-oxidation of nitride following of restoration of coolant. Key aspects of the model are the estimation of oxygen-stabilised alpha zirconium, α-Zr(O), formed during pre-oxidation and its reaction with the nitrogen. Nitriding of metallic Zr is much slower than α-Zr(O), and plays a comparatively minor role. The model is based on data from separate-effects tests comprised pre-oxidation, nitriding in the absence of oxidant, and re-oxidation in the absence of nitrogen, which were used to derive the kinetic parameters for the main reaction processes. Developmental assessment was performed using the test results, demonstrating favourable agreement for the main reaction signatures. Independent assessment against Integral Test data is underway

    Spectral Simplicity of Apparent Complexity, Part II: Exact Complexities and Complexity Spectra

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    The meromorphic functional calculus developed in Part I overcomes the nondiagonalizability of linear operators that arises often in the temporal evolution of complex systems and is generic to the metadynamics of predicting their behavior. Using the resulting spectral decomposition, we derive closed-form expressions for correlation functions, finite-length Shannon entropy-rate approximates, asymptotic entropy rate, excess entropy, transient information, transient and asymptotic state uncertainty, and synchronization information of stochastic processes generated by finite-state hidden Markov models. This introduces analytical tractability to investigating information processing in discrete-event stochastic processes, symbolic dynamics, and chaotic dynamical systems. Comparisons reveal mathematical similarities between complexity measures originally thought to capture distinct informational and computational properties. We also introduce a new kind of spectral analysis via coronal spectrograms and the frequency-dependent spectra of past-future mutual information. We analyze a number of examples to illustrate the methods, emphasizing processes with multivariate dependencies beyond pairwise correlation. An appendix presents spectral decomposition calculations for one example in full detail.Comment: 27 pages, 12 figures, 2 tables; most recent version at http://csc.ucdavis.edu/~cmg/compmech/pubs/sdscpt2.ht

    Cost-effectiveness analysis of the New South Wales adult drug court program

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    In New South Wales, Australia, a cost-effectiveness evaluation was conducted of an adult drug court (ADC) program as an alternative to jail for criminal offenders addicted to illicit drugs. This article describes the program, the cost-effectiveness analysis, and the results. The results of this study reveal that, for the 23-month period of the evaluation, the ADC was as cost-effective as were conventional sanctions in delaying the time to the first offense and more cost-effective in reducing the frequency of offending for those outcome measures selected. Although the evaluation was conducted using the traditional steps of a cost-effectiveness analysis, because of the complexity of the program and data limitations it was not always possible to adhere to textbook procedures. As such, each step involved in undertaking the cost-effectiveness analysis is discussed, highlighting the key issues faced in the evaluation. © 2004 Sage Publications

    Development of engineering solutions for air drilling at Dulisminsk oilfield, Irkutsk oblast

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    The article presents the analysis of disastrous mud loss achieved during casing at Dulisminsk oil and gas condensate field (DOGCF) and comparative evaluation of geological structure of DOGCF and Naryksko-Ostashkinsk area of Kemerovo oblast, where the same problem was solved successfully. On the basis of the analysis, an engineering solution is proposed to prevent mud loss in the conditions of DOGCF
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