Spiking Behavior in Chua's Circuit

Chua ＇s circuit with a slow-fast effect is established under certain parameter conditions. The dynamics of this slow- fast system is investigated. A spiking phenomenon can be observed in the numerical simulation. By introducing slow-fast analysis and a generalized Jacobian matrix at the non-smooth boundaries, the bifurcation mechanism for the periodic spiking solution, different from the smooth case, is discussed.     

模糊环境下部分权重信息的多属性群决策方法

针对决策过程中信息是模糊不确定的,属性的权重信息是部分可知的,我们给出了一个新的确定不同专家给出的属性值的权重的方法.该方法能将靠近中心值的属性值分配较大的权重,而给远离中心值的属性值分配较小的权重,从而得到更加合理的综合属性值.为了确定属性的权重信息,我们建立了一个线性规划模型.利用所给的新方法,我们给出了一个新的模糊多属性群决策方法.最后的实例说明方法的有效性和合理性.     

一类分布鲁棒优化问题的线性化方法及其应用

本文考虑一类特殊的极大极小化问题,即分布鲁棒优化问题.这类优化方法是不同于随机规划和鲁棒优化的一类方法,在这类问题中,不确定变量的概率分布往往是不能精确得知的,只知道概率分布所满足的一些条件,比如一次信息、二次信息以及支撑集合信息等.如此分布鲁棒优化问题便是寻求在所有满足条件的分布中找寻满足最坏可能分布的解.一般情况下,这类优化问题的求解都是NP难的.本文考虑一类简单的情形,即考虑不确定变量的概率分布只满足一次信息、支撑集合信息以及仿射一次信息,通过应用半无限规划问题的对偶性,本文指出这类分布鲁棒优化问题等价于线性规划问题,从而原分布鲁棒优化问题可以应用现成的求解线性规划的方法进行求解.为验证方法的有效性,本文将新方法应用于解决不确定条件下含有交易费用的利率管理问题.     

渐进非对称陀螺分子16O3及同位素16O18O16O的配分函数研究

采用乘积近似法计算了臭氧分子16O3及其同位素16O18O16O在20-6000 K温度范围内的总配分函数。其中转动配分函数用Watson的刚性转子模型,振动配分函数用谐振子模型．总的温度范围被划分为五个温度段。计算的配分函数在这五个温度段分别被拟合到一个温度T的五阶多项式,从而在每个温度段均得到六个拟合系数。由这些拟合系数就可以快速、准确的获得分子在所研究温度范围内任意温度的总配分函数。研究结果为目标特性识别、气动物理的高超声速技术等领域的研究提供了重要的参考信息。     

Study of q and η' physics at BES-Ⅲ

Decays of both η and η' provide very useful information in our understanding of low-energy QCD,and experimental signatures for these decays would be extremely helpful at BES-Ⅲ.The rare decays of the η and η' mesons could serve as a low-energy test of the Standard Model and its beyond.The sensitivities of the measurements of η and η' decays are discussed at BES-Ⅲ,in which the η and η' mesons are produced in the ψ decays.     

First-Principle Calculations for Elastic and Thermodynamic Properties of Diamond

The elastic constants and thermodynamic properties of diamond are investigated by using the CRYSTAL03 program. The lattice parameters, the bulk modulus, the heat capacity, the Grüneisen parameter, and the Debye temperature are obtained. The results are in good agreement with the available experimental and theoretical data. Moreover, the relationship between V/V₀ and pressure, the elastic constants underhigh pressure are successfully obtained. Especially, the elastic constants of diamond under high pressure are firstly obtained theoretically. At the same time, the variations of the thermal expansion α with pressure P and temperature T are obtained systematically in the ranges of 0-870 GPa and 0-1600 K.     

The Blood Flow at Arterial Bifurcations Simulated by the Lattice Boltzmann Method

The Programmed model of non-Newtonian blood fiow （the Casson model） at arterial bifurcations is established by the lattice Boltzmann method. The blood flow field under different Reynolds numbers is simulated, and distri- bution of dynamic factors such as flow velocity, shear stress, pressure and shear rate are presented. The existence of the fluid separation zone is analyzed. This provides a basis for further studies of the relationship between hemodynamic factors and pathogenesis, as well as a reference for a better understanding of the pathological changes and location of sediments, and the plague factor in arteries.     

带吸收系数的正倒向随机微分方程的可解性

利用叠代估计方法研究带吸收系数的正倒向随机微分方程的可解性,在正向随机微分方程的扩散系数可以退化的情形下,证明了适应解的存在性和唯-性,也研究这类正倒向随机微分方程与偏微分方程的联系.     

逆合成孔径成像激光雷达数据采样技术

逆合成孔径成像激光雷达能够实现对运动目标的高分辨实时成像,但激光信号的极大带宽和目标回波信号的微弱性给雷达回波数据的接收和处理带来了较大困难.针对这一问题,提出了基于光外差探测手段和压缩感知理论相结合的信号采样方法,首先通过光外差探测降低回波信号的有效带宽,再结合压缩感知理论实现对信号的稀疏化采样和重构.仿真结果证明了运用本文所提出的采样方法,在使用远低于奈奎斯特定理所规定的采样率时,仍然能够实现对目标的高质量成像.     

笙的簧片物理参数与音色相关性的初步研究

为了改善笙的声音品质,本文研究了笙的簧片物理尺度与笙的音色之间的相关性。在提出笙的物理模型并验证其有效性的基础上,固定音高,改变簧舌的厚度、长度以及缝隙宽度,合成一组笙的声样本。通过对偶比较法以及多维尺度法分析笙的音色空间,根据簧舌参数及音色特征量解释该音色空间的物理意义,并从发声原理比较簧舌参数对音色的作用。结果表明,音高一定时,簧舌宽度对音色的作用可忽略,厚度(及长度)和缝隙宽度对音色的作用相似,但影响方式不同。改变簧舌物理参数所形成的二维音色空间与声音的对数起振时间、频谱丰富性以及频谱不规则度有关。起振特征与频谱丰富性特征存在共变关系,通过改变这两个特征,能够改变音色的明亮度和柔软度。