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951.
A. Charalambopoulos D. I. Fotiadis C. V. Massalas 《Archive of Applied Mechanics (Ingenieur Archiv)》2000,70(5):307-322
Summary The present study is concerned with determining the dynamic characteristics of the human head-neck system which is described
as a fluid-filled spherical cavity supported by a viscoelastic neck reacting in three dimensions. The material of the skull
is assumed to be a homogeneous, isotropic, elastic material, and that of the brain-cerebrospinal fluid as an inviscid irrotational
fluid. The neck is approximated by a three-element viscoelastic model, the constants of which are computed by using experimental
data. The obtained results show that the viscoelastic properties of the neck affect only the first two eigenfrequencies and
the corresponding damping coefficients, while the remaining spectrum remains unchanged.
Received 18 December 1997; accepted for publication 23 April 1998 相似文献
952.
953.
Di-Rong Chen 《Journal of Approximation Theory》2000,107(2):204
This note studies Bessel sequences and frames of shift-invariant spaces generated by a countable set of periodic functions. We give characterizations under which the set of translations of the countable set is a Bessel sequence or a frame in terms of spectral decompositions of some self-adjoint operators. 相似文献
954.
We consider the ordinary M/M/1 queue with the FIFO queueing discipline. It seems that the sum of service times of the customers in the system (or the required work, as we call it briefly) is a random variable that is not considered before. In this paper we derive the equilibrium distribution of this variable. The task is not quite trivial because of the dependencies between the elapsed service time and the number of customers in the system. Our motivation for this problem comes from the performance analysis of a dynamic memory allocation scheme of a packet buffer. 相似文献
955.
李峥 《电子信息对抗技术》2002,16(1):39-42
信号处理是目前电子战技术发展的一个关键技术。不能单纯从信号处理本身来考虑如何实现信号处理 ,必须从系统角度设计信号处理 ,同时结合工作实践对信号处理提出一些建议。 相似文献
956.
The dynamic properties of the assistant sounders in the black cicada are given and the twitching properties of Contraction in the sounding muscle are revealed in this paper.For the operculum, tymbal cover and joint membrane, each of their vibration periods consists of three subgroup vibrations (SGV_(a,b,c)) corresponding to amplitude-modulation pulse trains (AMPT_(1,2,3)) in every syllable of synchro song. In comparison with the vibration at dorsum, the SGV_(a-c) have a subband with the function of regulating the tone. During calling song continuously, the pressure change inside the resonant cavity and the airspeed through the spiracles on both sides are about 7. 94—15.88 Paand 0.59—0.84 cm~3/s respectively, and they increase by about 7 and 2.6 times as the abdomen is moved. When the contraction motion of the sounding muscle comes up to the critical Sounding state, it further produces the twitching process, and drives the sounding membrane and the toning plate-membrane to produce AMPT_(1-3) and SGV_(a 相似文献
957.
Alcohol-water mixtures are often used as model systems for the study of hydrophobic interactions. In this respect, their thermodynamic
properties are of particular interest since precise data are available over the whole miscibility range and they lend themselves
readily to theoretical modelling. Three association models have been used to fit the volume data taken from the literature
for aqueous methonol, ethanol and n-propanol at various temperatures. A simple micellization equilibrium explains the general
trends but fails to fit the reduced excess volumes at both ends of the mole fraction scale. Better fits are obtained if interaction
parameters are introduced, but these two parameters cannot easily be rationalized. A double association model (one for the
alcohol and one for the water) gives the best fit and all the parameters have a physical significance. However, the parameters
extracted, e.g. aggregation numbers, and their trends with temperature are not always realistic. Despite their limitations,
these models illustrate well with the kind of avenues that can be explored to fit and interpret the experimental data of these
complex systems. 相似文献
958.
根据7个例子的对比分析表明:湿有效能量对预报暴雨具有较好的指示性,但在某些条件下湿有效能量在有无暴雨发生两者上并无明显差别。对暴雨和无暴雨个例的动力条件分析表明:(1)有暴雨时,在杭州地区为一个相对辐散区(300—900百帕),并伴有较强的上升运动,无暴雨时则为相对辐合区;(2)暴雨时高空有一支强的急流,暴雨区位于高空发散流场和急流中心的入口区右侧。(3)稳定度大小两者也有明显差异。分析结果对业务预报有一定参考价值。 相似文献
959.
结合最新病毒传播的研究工作,建立了一系列微观病毒传播系统,并对动态系统作了简单的分析,是对宏观疾病传播的内在规律的描述和研究,有利于疾病发展趋势的预测和最优化控制策略的研究. 相似文献
960.