Dynamics of Fokker-Planck Equation with Logarithmic Coefficients and Its Application in Econophysics

We demonstrate that Fokker Planck equations with logarithmic factors in diffusion and drift terms can be straightforwardly derived from the class of ＂constant elasticity of variance＂ stochastic processes without appealing to any symmetry argument, Analytical closed-form solutions are available for some special cases of this class of Fokker-Planck equations. The dynamics of the underlying stochastic variables are examined. These Fokker-Planck equations have found a rather wide range of applications in various contexts. In particular, in the field of econophysics we have demonstrated their immediate relevance to modelling the exchange rate dynamics in a target zone, e.g. the linked exchange rate system of the Hong Kong dollar. Furthermore, the knowledge of exact solutions in some special cases can be useful as a benchmark to test approximate numerical or analytical procedures.     

40GW重复频率脉冲驱动源研制进展

40 GW重复频率脉冲驱动源是应高功率微波技术发展等需求而设计的一台基于Tesla变压器技术的重复频率脉冲功率装置。40 GW驱动源设计输出功率40 GW,脉宽60 ns,重复频率1~50 Hz,输出功率及重复频率工作状态在一定范围内可调。介绍了40 GW高功率重复频率脉冲驱动源的系统构成、电气及结构参数的确定方法、关键部件的工程工艺技术,并分析了关键绝缘部件的电场分布。已完成驱动源安装并进行了实验调试,其主要单元Tesla变压器的能量效率达到70%,驱动源单次工作状态下输出功率大于40 GW;50Hz重复频率工作状态下,输出功率20.6 GW,系统工作稳定可靠。     

在险风险值估计方法的比较研究

金融数据呈现的厚尾性已达成共识。本文首先基于指数回归模型提出了一种厚尾分布的极值分位数估计方法,得到了在险风险值的估计公式。然后得到了上海上证指数、国债指数和企业债券指数的在险风险值的估计值,比较了他们的极值风险.     

谈电话机的发展

电话机,是电话系统的终端设备．自从美国科学家贝尔和沃森在1875年6月2日发明了世界上第一部电话机后,电话,这一名词,才在1876年3月7日贝尔申请发明电话的专利中首次出现,而人类利用电话机实现的第一次通话是贝尔和沃森于1876年3月10日在他们研究电话的实验室中实现的．从此,它宣告了人类历史上第一部真正具有实用价值的电话机的诞生,这就是原始的电磁式电话机．它从此改变了人们传统的交往方式,使人类文明又进入了新的发展时期．     

浅谈干挂花岗岩的质量控制措施

外墙干挂花岗岩，具有其独特的优点、是外墙幕墙施工的技术创新，它打破了建筑工程中采用花岗岩装饰板的种种限制，为高层、超高层建筑采用花岗岩进行外墙装饰开辟了广阔的前景。     

双调和Abel-Poisson算子对H(o)lder函数类的逼近

建立了双调和Abel-Poisson算子对H(o)lder函数类的逼近度的渐进等式,解决了双调和Abel-Poisson算子和H(o)lder函数类的Kolmogorov-Nikol'skii问题.     

一个经典不等式的再探究

文[1]得到以下结论: 命题A 若a1,a2,…,an∈R+,且a1+a2+…+an=s,P∈R,且|p|≥2,则 ∑ni=11/api(s-ai)≥np+2/sp+1(n-1).其实,关于上述不等式的研究很多文献早有出现.如:徐丹,杨露老师在2001年就已证明了p≤-2的情形[2],2003年,裘敬华老师将结果推广到p≤-1的情形[3].2010年,翁利帅老师[4]将p的范围推广到p∈(-∞,-1]U[0,+∞),但对于p∈(-1,0)的情形,翁老师自称还“留下一点遗憾”.笔者经一番探究,得到如下结论:     

单水听器被动测距的脉冲周期最接近法

为了解决单水听器对运动目标的被动测距的问题,提出了一种基于最小二乘的脉冲周期最接近法。该方法适用于目标发射固定周期脉冲信号,推导了目标运动参数与单水听器接受信号脉冲周期的关系式,构建一个长方矩阵,在最小二乘意义下,计算目标最接近距离和速度。使用泰勒展开公式,分析了算法的误差特性。为单水听器被动测距提供了新方法。仿真结果表明了新方法的正确性。     

Dependence of Structure and Haemocompatibility of Amorphous Carbon Films on Substrate Bias Voltage

Tetrahedral amorphous hydrogenated carbon (ta-C:H) films on Si(lO0) substrates were prepared by using a magnetic-field-filter plasma stream deposition system. Samples with different ratios of sp^3-bond to sp^2-bond were obtained by changing the bias voltage applied to the substrates. The ellipsometric spectra of various carbon films in the photon energy range of 1.9-5.4eV were measured. The refractive index n and the relative sp^3 C ratio of these films were obtained by simulating their ellipsometric spectra using the Forouhi-Bloomer model and by using the Bruggeman effective medium approximation, respectively. The haemocompatibility of these ta-C:H films was analysed by observation of platelet adhesion and measurement of kinetic clotting time. The results show that the sp^3 C fraction is dependent on the substrate bias voltage, and the haemocompatibility is dependent on the ratio of sp^3-bond to sp^2-bond. A good haemocompatibility material of ta-C:H films with a suitable sp^3 C fraction can be prepared by changing the substrate bias voltage.