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991.
Physical mechanism of the chaotic detection of the unknown frequency of weak harmonic signal and effects of damping ratio on the detection results 总被引:3,自引:0,他引:3 下载免费PDF全文
In the zero-order approximation, we use the perturbation method of parameter with small magnitude to prove that the harmonic frequency in the solution of the equation is close to that of the driving force when the chaotic system from Duffing-Holmes equation stays in the stable periodic state, which is the physical mechanism of the detection of the unknown frequency of weak harmonic signal using the chaotic theory. The result of the simulation experiment shows that the method proposed in this paper, by which one can determine the frequency of the stable system from the number of circulation change of the phase state directionally across a fixed phase state point (x,\dot{x}) in fixed simulation time period, is successful. Analyzing the effects of the damping ratio on the chaotic detection result, one can see that for different frequency ranges it is necessary to carefully choose corresponding damping ratio α. 相似文献
992.
In this paper, we study the relationship between the pull-off force and the transition parameter (or Tabor number) as well as the variation of the pull-off radius with the transition parameter in the adhesion elastic contact. Hysteresis models are presented to describe the contact radius as a function of external loads in loading and unloading processes. Among these models, we verified the hysteresis model from Johnson-Kendall-Roberts theory, based on which the calculated results are in good agreement with experimental ones. 相似文献
993.
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995.
In this paper, first we extend the known definition of cross-ratio of collinear points to whole Moufang plane. Later we introduce
the cross-ratios for lines, and we adapt the known results about the cross-ratios of points to cross-ratios of lines using
the principle of duality. Finally, we give a theorem which describes the relation between the cross-ratios of points and lines.
Received 2 March 2000; revised 22 November 2000. 相似文献
996.
A stochastic programming model using an endogenously determined worst case risk measure for dynamic asset allocation 总被引:2,自引:0,他引:2
We present a new approach to asset allocation with transaction costs. A multiperiod stochastic linear programming model is
developed where the risk is based on the worst case payoff that is endogenously determined by the model that balances expected
return and risk. Utilizing portfolio protection and dynamic hedging, an investment portfolio similar to an option-like payoff
structure on the initial investment portfolio is characterized. The relative changes in the expected terminal wealth, worst
case payoff, and risk aversion, are studied theoretically and illustrated using a numerical example. This model dominates
a static mean-variance model when the optimal portfolios are evaluated by the Sharpe ratio.
Received: August 15, 1999 / Accepted: October 1, 2000?Published online December 15, 2000 相似文献
997.
A. K. Gupta Bowling Green State University USA D. G. Kabe Sf. Mary''''s University USA 《数学物理学报(B辑英文版)》2001,21(2):221-223
1 IntroductionWe are given k independent Wishart densities of the p x p random symmetric positivedefinite matrices G1, G2,' t Gkwhere Ri denotes the population correlation matrir, and K as a generic letter denotes thenormalizing constants of density functions in this paper. The squared multiple correlationcoefficient of the i-th population is pf = r:Riz1.)ri, whereand a likelihood ratio test for testing the hypothesisis desired.Now Wilks (l932, l946) provides certain procedures and guidel… 相似文献
998.
刘旭阳 《数学的实践与认识》2001,31(3):257-263
文 [1 ]、[2 ]和 [3]主要是建立多传染阶段的艾滋病模型 ,并根据各自建立的模型 ,来讨论疾病传染的消除平衡态与流行平衡态以及它们的稳定性 .本文首先对文 [3]中的模型作适当的改进 ,再根据改进的数学模型来分析疾病传染的动态性质 ,着重讨论多传染阶段情况下艾滋病传染的持久性及其对总人数的影响 . 相似文献
999.
The desirable weight-to-axle power ratio for agricultural tractors is determined by the necessity for the optimum utilisation of the available axle power to produce the required drawbar pull at a preselected slip. For a vehicle designed to operate in a given speed range, the weight-to-axle power ratio should be within a particular limit, so that a specific level of conversion efficiency can be maintained. In this paper attempts have been made to select suitable tyres for Indian two-wheel drive tractors operating in sandy clay loam soils on the basis of weight-to-power utiisation and maximum pull-to-optimum weight ratio at a preselected slip using the developed traction prediction equations. A comparison has also been made between the desired and actual weight on a single traction wheel and suitable tyre and tyre normally fitted in Indian two wheel drive tractors up to 35 kW. 相似文献
1000.
考虑材料拉压异性的固支圆板塑性极统一解 总被引:1,自引:0,他引:1
本文采用最新的统一强度理论求出了固支圆板的塑性极限荷载,内力场及速度的统一解;得出了强度理论参数b及材料的不同拉压比α对塑性极限的影响曲线,所给出的解可以灵活地适用于各种不同特性的材料及机械、土木、航空等工程的相关结构中,文献中已有的Tresca解,Mises解和双剪统一屈服准则解均为本文的特例,本文的统一解还给出了一系列新的结果,统一解大于Tresca,Mohr-Coulomb的单剪理论解,它可以更好地发挥材料的强度潜力,工程应用可以取得明显的经济效益。 相似文献