SELF-ADAPTIVE MOLECULE/CLUSTER STATISTICAL THERMODYNAMICS METHOD FOR QUASI-STATIC DEFORMATION AT FINITE TEMPERATURE

Hybrid molecule/cluster statistical thermodynamics (HMCST) method is an efficient tool to simulate nano-scale systems under quasi-static loading at finite temperature.In this paper,a self-adaptive algorithm is developed for this method.Explicit refinement criterion based on the gradient of slip shear deformation and a switching criterion based on generalized Einstein approximation is proposed respectively.Results show that this self-adaptive method can accurately find clusters to be refined or transferred to molecules,and efficiently refine or transfer the clusters.Furthermore,compared with fully atomistic simulation,the high computational efficiency of the self-adaptive method appears very attractive.     

雷达遮盖性干扰效果评估度量方法研究

对雷达干扰的评估一直是电子战领域的难点和重点，文中对雷达干扰效果评估系统中如何完成干扰效果评估进行了研究，提出并讨论了基于发现概率损失、EMJ度量、发现距离损失和观察扇区损失四种雷达遮盖型干扰效果度量准则及其度量实现方法。通过试验证明，这些准则科学、合理、物理概念明确、便于实现度量，适用于电子战内、外场试验，对电子进攻也有一定的指导意义。     

Statistical space-time adaptive processing algorithm

For the slowly changed environment-range-dependent non-homogeneity, a new statistical space-time adaptive processing algorithm is proposed, which uses the statistical methods, such as Bayes or likelihood criterion to estimate the approximative covariance matrix in the non-homogeneous condition. According to the statistical characteristics of the space-time snapshot data, via defining the aggregate snapshot data and corresponding events, the conditional probability of the space-time snapshot data which is the effective training data is given, then the weighting coefficients are obtained for the weighting method. The theory analysis indicates that the statistical methods of the Bayes and likelihood criterion for covariance matrix estimation are more reasonable than other methods that estimate the covariance matrix with the use of training data except the detected outliers. The last simulations attest that the proposed algorithms can estimate the covariance in the non-homogeneous condition exactly and have favorable characteristics.     

扁平管管内负压冷凝流动阻力特性研究

本文采用试验的方法对扁平管内的负压蒸汽冷凝过程进行了研究。研究结果表明,这类扁管的特殊结构使得管内的蒸汽充满度高,冷凝液占据整个流动截面的份额小,流动顺利,阻力小,是很好的有利于冷凝液流动的管型。研究结果给出了这类扁平管的管内冷凝流动摩擦阻力的计算方法,为这类管型在空冷凝汽器的应用提供了设计依据。     

基于指数效用函数的酒店可替代产品的超订模型研究

本文考虑酒店收益管理中的超订问题.在考虑可替代因素和风险偏好的前提下,我们需决定每种房型的最佳超订量.我们把这个问题归结为两阶段最优化问题:在预定阶段,需决定最佳超订量;在分房阶段,将房型按现有预定进行分配,其中可以发生替代.我们得出,期望效用收益函数关于预定上限是子模函数.也就是说,一种房型的预定上限将随着其它产品预定上限的上升而下降.     

基于外信息收敛的Turbo码译码优化算法

目前Turbo码译码算法运算较复杂,无法满足LTE及LTE-Advanced的高速吞吐要求,因此,研究LTE环境下的Turbo码译码算法具有理论意义与工程价值。从降低译码延时考虑,评估各种迭代停止准则对性能及译码效率的影响,在分析外信息统计特性收敛的基础上,设计基于外信息收敛的双门限停止准则。仿真结果表明,改进的迭代停止准则在不影响译码性能的前提下,能较好地提高译码速率。     

Analysis of plate rolling by MY criterion and global weighted velocity field

A three-dimensional velocity field for plate rolling is proposed by global weighted method. Then, using the field and linear MY (mean yield) criterion, the power functional of internal deformation for plate rolling is analyzed. The collinear vector inner product is used in the friction power functional. Ultimately, analytical solution of total power functional is obtained. By minimizing the power functional, the rolling force and torque, as well as the stress effective factor are obtained. The calculated results by the solutions of rolling torque and force are compared with those of experimental ones. Good agreement is found and the maximum error percentage between them is less than 15.5%.     

海冰弯曲破坏下的破坏准则数值模拟方法研究

海冰的弯曲破坏进程的研究已经称为冰工程界的一项重要课题.通过理论分析结合数值计算对海冰弯曲破坏数值模拟方法进行探索:探讨适合于海冰弯曲应力状态下的本构模型和破坏准则;在LS-DYNA中模拟圆环形冰排弯曲破坏和冰排与锥体结构相互作用的进程,提出了一种对海冰破坏准则验证的技术思路;通过所提出的技术思路对基于三轴压缩试验的Derradji破坏准则进行了修正,使其能够适用于海冰的弯曲破坏.     

A note on randomized Shepp’s urn scheme

Shepp’s urn model is a useful tool for analyzing the stopping-rule problems in economics and finance. In [R.W. Chen, A. Zame, C.T. Lin, H. Wu, A random version of Shepp’s urn scheme, SIAM J. Discrete Math. 19 (1) (2005) 149-164], Chen et al. considered a random version of Shepp’s urn scheme and showed that a simple drawing policy (called “the k in the hole policy”) can asymptotically maximize the expected value of the game. By extending the work done by Chen et al., this note considers a more general urn scheme that is better suited to real-life price models in which the short-term value might not fluctuate. Further, “the k in the hole policy” is shown to be asymptotically optimal for this new urn scheme.     

一种利用序贯判决信息的雷达检测新方法

 在系统已获得一些判决信息的情况下,本文给出了一种新的可以利用这些判决信息的检测方法.系统已经获得的判决信息可以粗略地理解为关于目标的先验信息,利用这些判决信息可以修正系统当前时刻的判决规则,以提高系统的检测性能.本文分析并得出了该检测方法的似然比判决形式,给出了判决阈值的确定方法,并对系统的检测性能进行了评估.计算机仿真实验进一步验证了该检测方法的可行性.