共查询到20条相似文献,搜索用时 78 毫秒
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平面声波由空气经加肋板向水中传输的数值计算研究 总被引:5,自引:0,他引:5
采用有限元法和边界元法计算研究了平面声波由空气经加肋板向水中的声传输。数值计算表明:板的刚度对声传输的影响只有在板的刚度较大时才是重要的,当板的刚度较小时,空气和水之间的声阻抗失配对声传输起支配作用;板厚或肋骨惯性矩的变化会引起结构传声损失曲线上隔声低谷位置的变化;增大板厚或肋骨惯性矩可增大结构的传声损失,特别是当激励频率低于结构基频时,可通过增大板厚或肋骨惯性矩来增大结构刚度进而明显增大结构的传声损失。 相似文献
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侧向传声作为建筑中声传递的组成部分,对住宅的整体隔声效果具有重要的影响,通过将建筑中相邻房间的各建筑构件划分为若干子系统,应用统计能量分析(Statistical Energy Analysis,SEA)理论,从系统的声功率平衡的角度建立侧向传声的预测模型,在描述各路径的传声规律的同时确定主要传声路径。研究结果表明:当外围护结构为重质结构,且为匀质单一材料构造时,(1)在低频处,全程通过两相邻房间的侧墙或楼板的非通过隔墙的侧向路径成为主要侧向传声路径;(2)在中高频,各侧向路径的声压级差趋于一致,此时的建筑隔声性能取决于通过隔墙的直接路径上的声传递;(3)采用重质隔墙可以缩小侧向传声影响的频率范围。本研究为改善住宅的声环境质量及建筑隔声设计提供了理论依据。 相似文献
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文章探讨了实验室建筑构件隔声测量中填隙墙传声影响的检验与修正方法。通过实验分析,给出了三种可用于不同隔声量构件的门、窗和玻璃试件隔声测量的填隙墙构造方式。 相似文献
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《Superlattices and Microstructures》2000,27(5-6):301-310
A survey is presented on recent investigations of the metal-to-insulator transition in two-dimensional systems with special emphasis on n-Si–MOS structures. Experimental facts are presented and the currently open questions on the nature of this transition are addressed. 相似文献
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A. Guglielmi 《Physics of Atomic Nuclei》2000,63(6):1103-1109
The experimental status of neutrino oscillation searches at accelerators is presented, and the future medium and long baseline projects at CERN are discussed, including the knowledge on the neutrino beam production. Perspectives on future neutrino factories based on muon storage rings are also presented. 相似文献
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An overview of selected recent experimental results on fission times is presented. Evidences for over-damped motion up to saddle point during the fission process of highly excited nuclei have been obtained independently through fission probability, pre-scission multiplicity and direct time measurements. In addition, strong clues have been found for a temperature dependency of friction. Experiments probing transient effects through fission probabilities are presented and the counterbalanced effects of friction and level density parameters are discussed. Promising perspectives for super-heavy stability studies, based on fission time measurements, are presented. 相似文献
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Leonardo R. A. X. de Menezes A. H. Machado P. S. R. Sisnando H. Abdalla Jr. 《International Journal of Infrared and Millimeter Waves》1996,17(11):1927-1935
A new model of absorbing boundary for the TLM Method, based on absorvence condition on the node, is presented. Numerical and experimental results are presented; and the convergence aspect is discussed. 相似文献
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Shuzhen Fan Qingpu Wang Shutao Li Shuanghong Ding Fufang Su 《Optics Communications》2006,266(2):620-626
A method of more precise determination of the focal length of equivalent thermal lens (TL) is presented in this paper. The method is based on the diffraction theory of aberrations. By numerically calculating the optical path difference (OPD) distribution and the Strehl ratio, the focal lengths for “top-hat” pumping and Gaussian pumping are obtained and the equations for the focal lengths are presented by curve fitting. Also the equations for average pump radii are presented. The experiment on a fiber-coupled LD pumped Nd:YAG laser is carried out. The experimental results verify the validity of the method. 相似文献
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G. Masini S. La Monica G. Maiello S. Lazarouk V. Bondarenko 《Il Nuovo Cimento D》1996,18(10):1205-1212
Summary Porous-silicon-based white-light-emitting devices are presented. The fabrication process on different substrates is described.
The peculiarities of technological steps for device fabrication (porous-silicon formation and aluminum treatment) are underlined.
Doping profile of the porous layer, current-voltage characteristics, time response, lifetime tests and electroluminescence
emission spectrum of the device are presented. A model for electrical behaviour of Al/porous silicon Schottky junction is
presented. Electroluminescence spectrum of the presented devices showed strong similarities with white emission from crystalline
silicon junctions in the breakdown region.
Paper presented at the III INSEL (Incontro Nazionale sul Silicio Emettitore di Luce), Torino, 12–13 October 1995. 相似文献
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Detonative propulsion 总被引:8,自引:0,他引:8
Piotr Wolański 《Proceedings of the Combustion Institute》2013,34(1):125-158
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Emile H. L. Aarts Jan H. M. Korst Peter J. M. van Laarhoven 《Journal of statistical physics》1988,50(1-2):187-206
A quantitative study is presented of the typical behavior of the simulated annealing algorithm based on a cooling schedule presented previously by the authors. The study is based on the analysis of numerical results obtained by systematically applying the algorithm to a 100-city traveling salesman problem. The expectation and the variance of the cost are analyzed as a function of the control parameter of the cooling schedule. A semiempirical average-case performance analysis is presented from which estimates are obtained on the expectation of the average final result obtained by the simulated annealing algorithm as a function of the distance parameter, which determines the decrement of the control parameter. 相似文献