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We discuss an algorithmic approach for both deriving discrete analogues of Painlevé equations as well as using such equations to characterize similarity reductions of spatially discrete integrable evolution equations. As a concrete example we show that a discrete analogue of Painlevé I can be used to characterize similarity solutions of the Kac-Moerbeke equation. It turns out that these similarity solutions also satisfy a special case of Painlevé IV equation. In addition we discuss a methodology for obtaining the relevant continuous limits not only at the level of equations but also at the level of solutions. As an example we use the WKB method in the presence of two turning points of the third order to parametrize (at the continuous limit) the solution of Painlevé I in terms of the solution of discrete Painlevé I. Finally we show that these results are useful for investigating the partition function of the matrix model in 2D quantum gravity associated with the measure exp [–t
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稳瞄系统可靠性对直升机载武器系统可靠性具有重要影响。通过对产品可靠性概念和军用光电系统可靠性、直升机载稳瞄系统的功能和组成单元的阐述,给出了舰载直升机光电稳瞄系统的可靠性框图和数学模型。研究了舰载直升机稳瞄系统的可靠性影响因素和系统故障模式,探讨了稳瞄系统结构、光学和电气可靠性,提出通过计算机仿真对稳瞄系统可靠性进行预计分析的方法。某舰载直升机稳瞄系统在96 h可靠性试验过程中出现故障2次,达到MTBF≤32 h的可能性指标要求。对系统可靠性提前进行预估并采取相应的设计措施,保证产品可靠性达到设计要求,提高设计质量,缩短研制周期。 相似文献
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Form invariance and approximate conserved quantity of Appell equations for a weakly nonholonomic system
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A weakly nonholonomic system is a nonholonomic system whose constraint equations contain a small parameter. The form invariance and the approximate conserved quantity of the Appell equations for a weakly nonholonomic system are studied. The Appell equations for the weakly nonholonomic system are established, and the definition and the criterion of form invariance of the system are given. The structural equation of form invariance for the weakly nonholonomic system and the approximate conserved quantity deduced from the form invariance of the system are obtained. Finally, an example is given to illustrate the application of the results. 相似文献
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本文提出了一种新型双级间接蒸发冷却(IEC-TIEC)系统,其中普通叉流回热式间接蒸发冷却器(IEC)与热电辅助间接蒸发冷却器(TIEC)串联运行。建立了该系统的物理及数学模型,在不同热电制冷模块的运行参数(工作电流及模块数量)条件下,对比分析了新型双级间接蒸发冷却系统与单级热电辅助间接蒸发冷却(TIEC)系统的性能,结果表明IEC-TIEC系统的COP与露点效率均优于单级TIEC系统;研究了一次空气入口参数(温度、相对湿度、质量流量)对IEC-TIEC系统的COP与露点效率的影响规律。此外,对系统的四种不同质量流量分配比进行了优化分析,结果表明,存在最佳的质量流量分配比使得系统COP最大;在系统总换热面积一定的约束条件下,对系统中叉流回热式间接蒸发冷却器换热面积占系统总换热面积的比值进行了优化。 相似文献
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本文提出了一种新型双级间接蒸发冷却(IEC-TIEC)系统,其中普通叉流回热式间接蒸发冷却器(IEC)与热电辅助间接蒸发冷却器(TIEC)串联运行。建立了该系统的物理及数学模型,在不同热电制冷模块的运行参数(工作电流及模块数量)条件下,对比分析了新型双级间接蒸发冷却系统与单级热电辅助间接蒸发冷却(TIEC)系统的性能,结果表明IEC-TIEC系统的COP与露点效率均优于单级TIEC系统;研究了一次空气入口参数(温度、相对湿度、质量流量)对IEC-TIEC系统的COP与露点效率的影响规律。此外,对系统的四种不同质量流量分配比进行了优化分析,结果表明,存在最佳的质量流量分配比使得系统COP最大;在系统总换热面积一定的约束条件下,对系统中叉流回热式间接蒸发冷却器换热面积占系统总换热面积的比值进行了优化。 相似文献
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The generation of a hyperchaotic system based on a three-dimensional autonomous chaotic system 总被引:14,自引:0,他引:14
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This paper reports a new four-dimensional hyperchaotic system obtained by
adding a controller to a three-dimensional autonomous chaotic system. The
new system has two parameters, and each equation of the system has one
quadratic cross-product term. Some basic properties of the new system are
analysed. The different dynamic behaviours of the new system are studied when
the system parameter $a$ or $b$ is varied. The system is hyperchaotic in
several different regions of the parameter $b$. Especially, the two positive
Lyapunov exponents are both larger, and the hyperchaotic region is also
larger when this system is hyperchaotic in the case of varying $a$. The
hyperchaotic system is analysed by Lyapunov-exponents spectrum, bifurcation
diagrams and Poincar\'{e} sections. 相似文献
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光学合成孔径成像技术发展概况 总被引:4,自引:0,他引:4
介绍了光学合成孔径成像技术的发展现状。简要阐明了合成孔径成像技术的原理和分类以及在光学波段的主要应用。归纳出了光学合成孔径成像技术的发展趋势:地基合成孔径系统向长基线方向发展;天基系统向超轻量化方向发展;图像处理正在成为系统不可分割的一部分;技术重点是从地基系统向天基系统转移,并被应用于更多领域。概括了光学合成孔径成像系统的各种应用方案及特点。与传统的光学系统相比,合成孔径成像技术具有如下特征和优点:可降低光学元件的加工难度和天基光学合成孔径成像系统的发射体积和重量,可节约发射费用。 相似文献
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研究转动相对论Birkhoff约束系统积分不变量的构造首先,建立转动相对论系统的约束Birkhoff方程;其次,利用等时变分与非等时变分之间的关系建立系统的非等时变分方程;然后,研究转动相对论Birkhoff约束系统的第一积分与积分不变量之间的关系,证明由系统的一个第一积分可以构造一个积分不变量,并给出自由Birkhoff系统的相应结果;最后,讨论转动相对论Hamilton系统、相对论Birkhoff系统和Hamilton系统、经典转动系统和等时变分情形下的积分不变量的构造,结果表明相关的结论均为该定理的特款给出一个例子说明结果的应用
关键词:
转动相对论
Birkhoff系统
约束
第一积分
积分不变量 相似文献
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Symmetry of Hamiltonian and conserved quantity for a system of generalized classical mechanics
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This paper focuses on a new symmetry of Hamiltonian and its conserved quantity for a system of generalized classical mechanics.The differential equations of motion of the system are established.The definition and the criterion of the symmetry of Hamiltonian of the system are given.A conserved quantity directly derived from the symmetry of Hamiltonian of the generalized classical mechanical system is given.Since a Hamilton system is a special case of the generalized classical mechanics,the results above are equally applicable to the Hamilton system.The results of the paper are the generalization of a theorem known for the existing nonsingular equivalent Lagrangian.Finally,two examples are given to illustrate the application of the results. 相似文献
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为了在复杂及伪装的红外背景中识别出小温差目标,本文提出了一种基于分孔径的偏振成像系统结构,并对分孔径偏振成像系统所采用的分孔径成像系统及中继成像系统进行了设计研究。首先,根据Stokes矢量介绍了系统的工作理论和光学结构;其次,在现有探测器的结构参数要求下,计算出了光学系统的偏心量等参数,选择硅、锗作为透镜材料。在此基础上,确定了分孔径成像系统结构和中继成像系统结构。接着使用离轴偏心多重结构设计方法对初始结构进行了优化,研究了将普通红外物镜转变为具有实入瞳的像方远心结构的方法;最后,完成了分孔径成像系统和中继成像系统的整体系统匹配。设计结果表明,整体系统的调制传递函数在探测器奈奎斯特频率为17 lp/mm处大于0.6,能够满足系统的设计要求。本文设计的结构可以对探测目标实现实时偏振成像,且具有结构紧凑的优点。 相似文献
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介绍了聚光光伏系统的发展历史和研究现状。对聚光光伏系统中的主件一聚光器和光伏电池进行了详细分类,给出了它们的特点和主要参数。描述了国外一些厂家为提高光伏系统效率并降低成本而研制的太阳跟踪系统。总结出聚光光伏系统的发展趋势,主要是指高倍聚光器+跟踪系统和低倍大角度聚光器+分光元件+多节电池等。最后就目前状况提出了聚光光伏系统商业化还需要解决的问题。 相似文献
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In the present work, the new exact solutions of the Boiti-Leon-Pempinelli system have been found. The system has extensive physical background. The exact solutions of the Boiti-Leon-Pempinelli system are investigated using similarity transformation method via Lie group theory. Lie symmetry generators are used for constructing similarity variables for the given system of partial differential equations, which lead to the new system of partial differentiaJ equations with one variable less at each step and eventually to a system of ordinary differential equations (ODEs). Finally, these ODEs are solved exactly. The exact solutions are obtained under some parametric restrictions. The elastic behavior of the soliton solutions is shown graphically by taking some appropriate choices of the arbitrary functions involved in the solutions. 相似文献