The burglar problem with multiple options

We consider the burglar problem in which a burglar can either retire or choose among different types of burglaries, with each type having its own success probability and reward distribution. Some general structural results are established and, in the case of exponentially distributed reward distributions, a solution technique is presented. The burglar problem's relationship to a stochastic knapsack problem with a random exponentially distributed knapsack capacity is shown. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 359–364, 2014     

A branch‐and‐price approach for the stochastic generalized assignment problem

In this article, we address a stochastic generalized assignment machine scheduling problem in which the processing times of jobs are assumed to be random variables. We develop a branch‐and‐price (B&P) approach for solving this problem wherein the pricing problem is separable with respect to each machine, and has the structure of a multidimensional knapsack problem. In addition, we explore two other extensions of this method—one that utilizes a dual‐stabilization technique and another that incorporates an advanced‐start procedure to obtain an initial feasible solution. We compare the performance of these methods with that of the branch‐and‐cut (B&C) method within CPLEX. Our results show that all B&P‐based approaches perform better than the B&C method, with the best performance obtained for the B&P procedure that includes both the extensions aforementioned. We also utilize a Monte Carlo method within the B&P scheme, which affords the use of a small subset of scenarios at a time to estimate the “true” optimal objective function value. Our experimental investigation reveals that this approach readily yields solutions lying within 5% of optimality, while providing more than a 10‐fold savings in CPU times in comparison with the best of the other proposed B&P procedures. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 131–143, 2014     

微槽结构单点金刚石飞切加工的切削力建模

超精密单点金刚石飞刀切削技术是一种比较新颖的微槽类结构加工方式。在飞切过程中,切削力是切削过程中重要的物理量,对加工后的表面质量、刀具磨损等有着直接影响。提出了一种基于直角微切削理论的动态微槽类结构飞切的力学模型,基于微切削理论,得到了前、后刀面切削力的理论模型。根据飞切的几何运动特征,建立了飞切过程中剪切角的计算模型,并根据单圈飞切实验得到了飞切过程中剪切面的变化规律。为了验证模型的正确性,采用不同切削参数进行了多圈重叠飞切实验,对切削力进行了测量和分析。实验得到的切削力大小和变化规律与理论模型计算得到的基本一致,证明了该切削力模型的有效性。     

DEFENSIVE COUNTERTERRORISM MEASURES AND DOMESTIC POLITICS

Unlike most of the literature, this paper includes domestic political considerations in which two countries must decide defensive countermeasures against a common terrorist threat. A delegation problem arises as voters strategically choose a policymaker whose preferences differ from their own. As a consequence, countries limit the presumed oversupply of defensive countermeasures. Thus, the inclusion of domestic politics gives a new perspective on counterterrorism. The timing of elections is also shown to make a difference.     

THE MORAL PERMISSIBILITY OF AUTOMATED RESPONSES DURING CYBERWARFARE

Automated responses are an inevitable aspect of cyberwarfare, but there has not been a systematic treatment of the conditions in which they are morally permissible. We argue that there are three substantial barriers to the moral permissibility of an automated response: the attribution, chain reaction, and projection bias problems. Moreover, these three challenges together provide a set of operational tests that can be used to assess the moral permissibility of a particular automated response in a specific situation. Defensive automated responses will almost always pass all three challenges, while offensive automated responses typically face a substantial positive burden in order to overcome the chain reaction and projection bias challenges. Perhaps the most interesting cases arise in the middle ground between cyber-offense and cyber-defense, such as automated cyber-exploitation responses. In those situations, much depends on the finer details of the response, the context, and the adversary. Importantly, however, the operationalizations of the three challenges provide a clear guide for decision-makers to assess the moral permissibility of automated responses that could potentially be implemented.     

基于相位估计的湍流降质图像盲复原

地基望远镜观测的空间目标图像受大气湍流的影响,其分辨率受到很大的限制。为了提高湍流降质图像的复原效果,提出一种改进的盲解卷积方法。首先,考虑观测图像受到高斯噪声和泊松噪声的干扰,推导出基于混合噪声模型的盲解卷积代价函数;然后,根据傅里叶光学原理,利用波前相位表示点扩展函数,将点扩展函数从像素值估计转换为参数估计;最后,通过参数化表示方式,将代价函数寻优从约束最优化问题转换为无约束最优化问题。模拟实验结果验证了本文模型与数值算法的有效性。     

带点缺陷的一维亥姆霍兹共振腔声子晶体中缺陷模式

在基于亥姆霍兹共振腔的一维声子晶体中引入点缺陷会在原有局域共振型声禁带内产生缺陷模式。采用传递矩阵法和有限元法分析了缺陷模式随缺陷单元几何尺寸变化关系和声子晶体中声场分布情况。结果表明,随着缺陷单元与完美单元之间耦合程度的增强,缺陷模式从局域共振型禁带中完美单元共振频率处向禁带边缘移动。同时,缺陷模式的存在使得结构中出现了能量局域化的现象。本工作对设计新型声滤波器、能量集中装置具有一定的理论意义。     

基于时频单源点检测和聚类验证技术的欠定混合盲辨识算法

针对欠定混合盲辨识问题,提出了一种基于时频单源点检测及聚类验证的盲辨识算法。检测各个源信号的时频单源点,利用奇异值分解的方法求解不同单源点集合对应的混合矢量,利用基于k均值的聚类验证技术完成源信号数目和混合矩阵的联合估计。算法放宽了已有方法对时频单源区域的假设,不需要假设信号存在时频单源区域,可以完成仅存在离散的时频单源点条件下的欠定混合盲辨识;同时克服了传统算法需要假设源信号个数已知的不足,可以有效地估计源信号数目。仿真结果验证了算法的有效性。     

囿于控制多边形的NURBS拐点分析与控制

从变形的观点出发,首先研究了一般平面参数曲线变形过程中产生拐点的充分必要条件以及判定拐点的一个泛函方程。在此基础上,给出了研究非凸控制多边形NURBS曲线拐点的方法,特别研究了正则单拐、双拐多边形NURBS曲线拐点的分布问题,得到了分析与控制相应曲线拐点的条件和判据。本文的结果可应用于调节与控制曲线形状的算法设计,也可指导CAD造型工程师的交互设计。     

船用堆物理启动外推临界曲线优化研究

外推临界监督是反应堆物理启动过程中的重要安全保证,控制棒积分价值的非线性和反应堆内的中子泄漏都对外推的准确性有重要影响.针对这种情况提出了一种综合考虑控制棒价值与堆芯泄漏的外推方法,提高了外推的准确性.