Some Cracks in the Empire of Chance (Flaws in the Foundations of Reliability)

Making quantified statements about the uncertainty associated with the lifelength of an item is one of the most fundamental tasks of reliability assessment. Most practitioners routinely do this using one of the several available statistical techniques. The purpose of this paper is two-fold. The first is to give the user an overview of the key tenets of two of the most commonly used parametric approaches. The second is to point out that these commonly used approaches involve strategies that are either ad hoc, or are in violation of some of the underlying tenets. A method that is devoid of logical flaws can be proposed, but this method is difficult to implement. The user must therefore resign to using that technique against which the fewest objections can be hurled.     

钢结构随机有限元动力分析

钢结构在应用一段时间后,物理参数和几何参数的变化将导致结构参数发生某些不确定性的改变, 这将会影响结构的力学特性.从此问题出发,通过一个算例详细阐述了用摄动随机有限元法解决此类问题的实现过程.     

PRICING DERIVATIVES ON MULTISCALE DIFFUSIONS: AN EIGENFUNCTION EXPANSION APPROACH

Using tools from spectral analysis, singular and regular perturbation theory, we develop a systematic method for analytically computing the approximate price of a large class of derivative‐assets. The payoff of the derivative‐assets may be path‐dependent. In addition, the process underlying the derivatives may exhibit killing (i.e., jump to default) as well as combined local/nonlocal stochastic volatility. The nonlocal component of volatility may be multiscale, in the sense that it may be driven by one fast‐varying and one slow‐varying factor. The flexibility of our modeling framework is contrasted by the simplicity of our method. We reduce the derivative pricing problem to that of solving a single eigenvalue equation. Once the eigenvalue equation is solved, the approximate price of a derivative can be calculated formulaically. To illustrate our method, we calculate the approximate price of three derivative‐assets: a vanilla option on a defaultable stock, a path‐dependent option on a nondefaultable stock, and a bond in a short‐rate model.     

马克思经济增长模型中的特征值及其理论蕴涵

为了借鉴现代经济增长模型的数量方法对马克思经济增长理论的研究,本文基于马克思两部类经济增长模型的特殊结构,将特征值方法探索运用于对其的研究。通过解析两个部类积累相互约束的关系,以及每个部类新创造价值增长与本部类积累和两个部类结构参数之间的关系,获得两个部类新创造价值的唯一特征值,也就是唯一的均衡发展速度。给出与特征值对应的全社会和每个部类积累率算式,指出产生特征值的模型结构条件,以及特征值的最大值。从经济均衡和非均衡增长的视角,通过与哈罗德经济增长模型的对比分析,阐述了马克思两部类经济增长模型中的特征值的理论蕴涵。最后引用和借鉴《资本论》中的举例,对所论析做了算例验证。     

螺旋波纹波导回旋行波管色散特性仿真分析

对螺旋波纹波导回旋行波管的冷腔色散特性进行了研究,通过理论分析和数值计算,得到了螺旋波纹波导的冷腔色散方程和色散曲线,并分析了几何结构参数变化对其色散特性的影响。同时利用三维电磁仿真软件HFSS对螺旋波纹波导进行建模和计算。     

THE BLACK-SCHOLES EQUATION REVISITED: ASYMPTOTIC EXPANSIONS AND SINGULAR PERTURBATIONS

In this paper, novel singular perturbation techniques are applied to price European, American, and barrier options. Employment of these methods leads to a significant simplification of the problem in all cases, by reducing the number of parameters. For American options, the valuation problem is reduced to a procedure that may be performed on a rudimentary handheld calculator. The method also sheds light on the evolution of option prices for all of the cases considered, the results being particularly illuminating for American and barrier options.     

Linear programing models for portfolio optimization using a benchmark

We consider the problem of constructing a perturbed portfolio by utilizing a benchmark portfolio. We propose two computationally efficient portfolio optimization models, the mean-absolute deviation risk and the Dantzig-type, which can be solved using linear programing. These portfolio models push the existing benchmark toward the efficient frontier through sparse and stable asset selection. We implement these models on two benchmarks, a market index and the equally-weighted portfolio. We carry out an extensive out-of-sample analysis with 11 empirical datasets and simulated data. The proposed portfolios outperform the benchmark portfolio in various performance measures, including the mean return and Sharpe ratio.     

A Novel Compact Cat Swarm Optimization Based on Differential Method

ABSTRACT

A compact cat swarm optimization scheme (cCSO) is proposed in this paper, which is designed to solve application domains plagued with limited memory and less-computation power, as a member of cat swarm optimization algorithms (CSO), it composes of two sub-modes, i.e., tracing and seeking modes, so it keeps the same search logic of CSO. On the other hand, cCSO inherits the main feature of compact algorithms, a normal probabilistic model is used to represent the population of solutions instead of processing an actual population, which ensures the cCSO to have the modest memory requirement. The updating vector for the probabilistic model provides a clear moving direction for cats in next step. A cat without historical position and velocity is applied in the algorithm. When the cat is in seeking mode, it employs a differential operator to update the cat’s position, which makes it possible for the cat to have multiple searching directions. Experimental results show that cCSO has pretty performance compared with respect to some population-based testing benchmarks. And it also shows superior performance in convergence rate to some compact optimization algorithms. The case study of gray image segmentation proves that it suits for solving the optimization problem by limited hardware.     

一类相同材料焊接问题的稳定性

文章讨论了相同材料带一个孔洞无限平面焊接问题的稳定性,通过引进两个全纯函数,把焊接问题转化为黎曼边值问题中的跳跃问题,从而得到应力函数的表达式,借助柯西型积分关于积分曲线和核密度的稳定性来研究其稳定性,并给出误差估计。     

内部控制指数的分析与再设计初探

设计内部控制指数,可以降低内部控制制度设计方面的主观因素,把定性因素量化,以此衡量内部控制的效率,并为利益相关者提供可量化的决策参考。本文基于现有的研究成果,结合内部控制的目标和要素,设置评价指数和评分标准,信息使用者通过计算总分数来评价内部控制效率,从而形成具有完整性、层次性的内部控制指数体系。