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71.
E. E. Son Al. F. Gaisin M. A. Leushka Az. F. Gaisin R. Sh. Sadriev F. M. Gaisin 《High Temperature》2016,54(1):26-28
We present the results of experimental study of the electric discharge between metal electrodes of various geometry and technical water within the pressure range of 8 × 103–105 Pa at the saw-tooth voltage generator frequency, f = 40 MHz, and the interelectrode distance, l = 3–30 mm. We consider transfer of the streamer discharge into spark one depending on the geometry of the metal electrode and its material. We investigate the electrical characteristics of the discharge between the plate electrode and the technical water within a wide pressure range. The essential influence of the streamer discharge type on the ozone release within the investigated parameters range is discovered. 相似文献
72.
Sh. Khorasanizade J. M. M. Sousa 《International journal for numerical methods in engineering》2016,106(5):397-410
In this work, a dynamic procedure for local particle refinement to be used in smoothed particle hydrodynamics (SPH) is presented. The algorithm is able to consistently produce successive levels of particle splitting in accordance to a flow‐based criterion. It has been applied together with accurate and robust formulations for variable spatial resolution in the framework of a semi‐implicit, truly incompressible scheme for SPH. Different test cases have been considered to assess the capabilities and advantages of the proposed procedure, namely, the laminar flow around circular and square obstacles in a plane channel for various regimes. Such flow cases entail the simulation of attached and separated shear layers, recirculating flow, vortex shedding and surface discontinuities. The results obtained for two levels of particle splitting have demonstrated that significant improvements may be obtained with respect to uniform particle spacing solutions in a variety of situations, thus presenting an excellent trade‐off between accuracy and computational cost. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
73.
74.
This paper presents an innovative application of a new class of parallel interacting Markov chains Monte Carlo to solve the Bayesian history matching (BHM) problem. BHM consists of sampling a posterior distribution given by the Bayesian theorem. Markov chain Monte Carlo (MCMC) is well suited for sampling, in principle, any type of distribution; however the number of iteration required by the traditional single-chain MCMC can be prohibitive in BHM applications. Furthermore, history matching is typically a highly nonlinear inverse problem, which leads in very complex posterior distributions, characterized by many separated modes. Therefore, single chain can be trapped into a local mode. Parallel interacting chains is an interesting way to overcome this problem, as shown in this paper. In addition, we presented new approaches to define starting points for the parallel chains. For validation purposes, the proposed methodology is firstly applied in a simple but challenging cross section reservoir model with many modes in the posterior distribution. Afterwards, the application to a realistic case integrated to geostatistical modelling is also presented. The results showed that the combination of parallel interacting chain with the capabilities of distributed computing commonly available nowadays is very promising to solve the BHM problem. 相似文献
75.
以建立精确的对接圆柱壳结构动力学模型为目标,为解决对接圆柱壳结构实验模型存在的界面转角自由度信息缺失的问题,提出了频响函数子结构混合建模方法,采用界面刚性等效方法进行界面转角自由度信息的近似估计,并将其与有限元频响结果进行对比分析,验证了该方法在圆柱壳结构中的计算精度。同时,根据子结构频响函数获取方式、界面自由度的不同,采用子结构频响函数综合方法进行多种工况下的混合建模。结合对接圆柱壳结构的振动特性,对比分析不同工况下的混合建模结果。结果表明:考虑界面转角自由度信息后,可有效提高对接圆柱壳结构的混合建模精度。 相似文献
76.
To determine the optimum conditions of fracturing or altering the trajectory of dangerous space objects (large iron or rock space bodies, threatening to collide with the Earth), and also destroy space debris in the space around the Earth, the author presents a mathematical formulation of the problem of calculating the dynamic strength of solids under the effect of high-energy loading pulses. The results of numerical modeling are compared with the experimental data for the formulation of cupola-shaped swollen areas on the rear surface of a metallic plate subjected to laser radiation. The change in the fracture mechanisms (front and rear spallation) with increasing energy of the effect has been detected. Recommendations are given for optimizing the pulsed laser effect on dangerous space objects to ensure the fragmentation or change their orbit.Expanded form of the document presented at the International Conference Space Protection of the Earth≓ (SPE'94, Snezhinsk, Russian, September 26–30, 1994).Translated from Problemy Prochnosti, No. 3, pp. 31–51, March, 1996. 相似文献
77.
A. V. Bogachev E. A. Vorob’eva N. E. Zubov E. A. Mikrin M. Sh. Misrikhanov V. N. Ryabchenko S. N. Timakov 《Journal of Computer and Systems Sciences International》2011,50(3):483-490
The problem of gravitational unloading of the angular momentum of inertial actuators of a spacecraft in the pitch channel
for circular and elliptic orbits is considered using the band theory of modal control. Control laws for gravitational unloading
and stabilization of a given spacecraft position unambiguously determined by the object parameters and given coefficients
of characteristic equation are obtained. 相似文献
78.
Dmitry Lizorkin Pavel Velikhov Maxim Grinev Denis Turdakov 《The VLDB Journal The International Journal on Very Large Data Bases》2010,19(1):45-66
The measure of similarity between objects is a very useful tool in many areas of computer science, including information retrieval.
SimRank is a simple and intuitive measure of this kind, based on a graph-theoretic model. SimRank is typically computed iteratively,
in the spirit of PageRank. However, existing work on SimRank lacks accuracy estimation of iterative computation and has discouraging
time complexity. In this paper, we present a technique to estimate the accuracy of computing SimRank iteratively. This technique
provides a way to find out the number of iterations required to achieve a desired accuracy when computing SimRank. We also
present optimization techniques that improve the computational complexity of the iterative algorithm from O(n
4) in the worst case to min(O(nl), O(n
3/ log2
n)), with n denoting the number of objects, and l denoting the number object-to-object relationships. We also introduce a threshold sieving heuristic and its accuracy estimation
that further improves the efficiency of the method. As a practical illustration of our techniques, we computed SimRank scores
on a subset of English Wikipedia corpus, consisting of the complete set of articles and category links. 相似文献
79.
Julien Fleureau Karim Bensalah Denis Rolland Olivier Lavastre Nathalie Rioux-Leclercq François Guillé Jean-Jacques Patard Renaud de Crevoisier Lotfi Senhadji 《Expert systems with applications》2011,38(11):14301-14306
In this study, we propose to evaluate the potential of Raman spectroscopy (RS) to assess renal tumours at surgery. Different classes of Raman renal spectra acquired during a clinical protocol are discriminated using support vector machines classifiers. The influence on the classification scores of various preprocessing steps generally involved in RS are also investigated and evaluated in the particular context of renal tumour characterization. Encouraging results show the interest of RS to evaluate kidney cancer and suggest the potential of this technique as a surgical assistance during partial nephrectomy. 相似文献
80.
Applications implemented on critical systems are subject to both safety critical and real-time constraints. Classically, applications are specified as precedence task graphs that must be scheduled onto a given target multiprocessor heterogeneous architecture. We propose a new method for simultaneously optimizing two objectives: the execution time and the reliability of the schedule. The problem is decomposed into two successive steps: a spatial allocation during which the reliability is maximized (randomized algorithm), and a scheduling during which the makespan is minimized (list scheduling algorithm). It allows us to produce several trade-off solutions, among which the user can choose the solution that best fits the application’s requirements. Reliability is increased by replicating adequate tasks onto well chosen processors. Our fault model assumes that processors are fail-silent, that they are subject to transient failures, and that the occurrences of failures follow a constant parameter Poisson law. We assess and validate our method by running extensive simulations on both random graphs and actual application graphs. They show that it is competitive, in terms of makespan, compared to existing reference scheduling methods for heterogeneous processors (HEFT), while providing a better reliability. 相似文献