Stability in a general oligopoly model

We analyze a general but parsimonious price competition model for an oligopoly in which each firm offers any number of products. The demand volumes are general piecewise affine functions of the full price vector, generated as the “regular” extension of a base set of affine functions. The model specifies a product assortment, along with their prices and demand volumes, in contrast to most commonly used demand models. We identify a fully best response operator which is monotonically increasing so that the market converges to a Nash equilibrium, when firms dynamically adjust their prices, as best responses to their competitors' prices, at least when starting in one of two price regions. Moreover, geometrically fast convergence to a common equilibrium can be guaranteed for an arbitrary starting point, under an additional condition for the price sensitivity matrix.     

修正的响应面方法优化螺栓法兰连接结构几何参数

采用响应面法对螺栓法兰连接进行优化设计时,考虑到经典响应面模型的局限性,在获得结构优化参数与响应指标内在联系的基础上,提出了修正响应面模型;设计了数值试验并对比了数值试验值与前述两种响应面模型预测值,结果表明修正响应面模型的预测值不仅误差相对比较均匀,且最大误差绝对值要明显小于经典响应面模型的相应值。采用遗传算法对修正响应面模型进行了以法兰质量最轻为优化目标的参数优化,取得了比较理想的优化结果。     

Humanitarian response to hurricane disasters: Coordinating flood‐risk mitigation with fundraising and relief operations

To alleviate flooding, caused by hurricanes, governments build structural barriers called levees. In addition, relief providers such as the nongovernmental organizations and charities raise funds, and procure and deliver supplies (food, water, and medicines) for humanitarian relief. The strategy for managing disasters must, therefore, weigh the costs and benefits of building levees as well as procuring and delivering supplies. We use a three‐stage decision making framework to study how the investment in levee capacity can be integrated with supply procurements, fundraising, and rapid response. One of our major findings is that a large fundraising cost discourages postdisaster funding, implying relatively large investments in levee and prepositioned supplies. That notwithstanding, a large social value (of saving life) can tilt the balance in favor of postdisaster funding. If the levee capacity increases, funding for predisaster procurement is reduced without affecting postdisaster funding. For a sufficiently large increase in capacity, however, postdisaster response becomes superfluous. We also find that hurricane uncertainty motivates levees with large capacity. In contrast, levee‐failures motivate levees with small capacity.     

马尔可夫随机场中应用蚁群系统的红外图像分割

利用蚁群系统(ACS)的信息正反馈和启发式的搜索特点,针对马尔可夫随机场(MRF)图像模型的局部相关特性和最大后验概率(MAP)估计,可以在较短时间内得到图像分割目标函数的全局最优解,从而可以避免传统模拟退火算法的庞大时间复杂度.通过对军用红外图像的分割实验,可以看出这种算法能够在抗噪声、保留目标边缘和降低时间复杂度方面得到较满意的结果.     

基于混沌量子粒子群的舰炮身管多目标优化研究

舰炮的炮口扰动是影响舰炮射击精度的重要因素。为了减少舰炮的炮口扰动,优化身管结构,建立了柔性身管的有限元模型并将该模型的模态计算结果与模态试验测试值进行对比,证明建立的柔性身管有限元模型是有效的。提出了混沌量子粒子群算法与动力学联合优化的方法,进行身管和炮口的多目标优化,优化结果表明：优化后的炮口中心的线速度、角速度和角位移与优化前相比显著减小,身管质量有所降低,结构更加合理,该优化方法有效可行,为下一步全炮总体优化设计提供了一定的借鉴。     

当前消防部队灭火救援工作存在问题及解决对策

近年来,全国消防部队开展了轰轰烈烈的执勤岗位大练兵工作,灭火救援一线官兵素质普遍得到提高,然而,随着社会的发展,兵员结构的变化和兵役制度的改革,消防部队在参加灭火救援工作还存在一些问题。分析了当前消防部队参加灭火救援工作存在的问题,并提出了相应解决对策。     

基于均匀设计的临近空间无动力攻击器运动参数响应面建模

为探求临近空间无动力攻击器运动参数的解析模型,采用均匀设计试验方法,以攻击器发射参数为设计变量,从设计空间中选择一些特定的设计点,构造了临近空间攻击器速度、射程以及飞行时间的响应面模型。通过仿真算例,对各响应面模型分别进行显著性检验,证明了所建立的响应面都具有较高的近似精度。     

超空泡体结构响应问题的有限元分析

超空泡体在水下高速航行时要受到冲击载荷的作用,这对其结构是不利的。用有限元方法分析计算了冲击载荷作用下超空泡体的结构响应,数值计算结果表明,超空泡体在一定频率下引起的结构响应非常显著,且随着频率的升高响应幅值有减小的趋势。     

基于响应面法的复合材料层合板平面应力强度可靠性分析

针对处于平面应力状态下的复合材料层合板,考虑其材料参数、强度参数、几何尺寸以及承受载荷等随机因素,用分支限界法识别结构系统的各重要失效序列,应用响应面法对某具体层合板的各失效事件进行计算,进而计算出整个系统的失效概率,并且利用MATLAB程序以及ANSYS中的APDL语言编写了JC法计算程序。计算结果表明,一般情况下层合板首先出现基体损伤失效,然后才会出现纤维断裂失效。这一结果与一些文献中的试验结果相一致,表明这种概率分析方法可以应用于实际复合材料层合板结构的可靠性分析。     

坦克嵌入式车场射击训练炮长操纵控制模型

在嵌入式射击模拟训练系统中,针对炮长操作过程对模拟训练的影响,建立了炮长操纵控制模型。炮长操纵控制模型包括炮长操纵模型和炮长射击决策模型。炮长操纵模型的建立是基于装备的物理模型和人的生理反应模型。炮长射击决策模型根据坦克射击教范要求,采用与/或正向演绎推理得到。在炮长操纵控制模型基础上,建立了射击反应时间模型,并与实际装备操作进行了比较,对建立的操纵控制模型进行了验证。