导弹结构热防护一体化设计与优化

针对导弹面临的严酷气动热力环境,基于传统波纹夹芯结构,为导弹设计了一种兼具承载和热防护功能的一体化结构。建立热-结构耦合计算模型,对一体化结构进行结构承载与热防护性能分析,结果表明:一体化结构在高温下具有较好的承载能力;增加一体化结构隔热层与内壁厚度有助于提高导弹的热防护效率。以一体化结构热防护效率最高和质量最小为目标,采用第二代非支配排序遗传算法实现了多目标优化,并认识到:一体化结构热防护效率与质量相互影响,设计时需要需综合考虑。     

采用瞬态球状热斗篷方法的浅层地下目标红外隐身技术

由于浅层地下目标与背景土壤的热物性不同,影响了整个区域表面的温度场分布,容易被敌方探测系统发现并击毁。针对这一问题,考虑太阳辐射、天空辐射以及风速的影响,建立了埋藏地下目标的区域温度分布传热模型,揭示了不同时段埋藏地下目标对区域表面温度场的影响。在变换热力学的基础上,通过坐标变换的方法,推导出球状瞬态热斗篷的导热系数的通解表达式。根据等效介质理论,对设计的热物性参数进行均质化,并通过数值实验方法验证了基于热斗篷地下目标红外隐身技术的可行性。     

可展开遮阳罩技术研究进展及其关键科学问题

可展开遮阳罩一般是由多层轻质柔性高精度无褶皱薄膜和展开支撑臂及其控制装置组成,在轨后展开支撑臂有序展开多层大面积薄膜实现光控制和热控制性能,能有效改善和防护空间航天器。针对可展开遮阳罩结构,依据一维轴向、二维平面与三维周向的展开方式分类总结国内外可展开遮阳罩技术的研究进展,并对不同遮阳罩结构形状、薄膜材料、层数与展开方式等进行对比分析;梳理出遮阳罩在杂光抑制、折叠与展开变形机理、极端环境下薄膜多场耦合、低温热控、太阳辐射光压力矩及其计算方法等方面的关键科学问题,并给出了中国研究遮阳罩的发展建议。     

移动式铁路油罐车清洗装置水循环使用与节能分析

装备节能研究对建设绿色节能型社会具有重要意义。对移动式铁路油罐车清洗装置中清洗管路和吸污管路的热损进行分析计算,提出了水掺混循环使用的节能清洗方案,对清洗工艺中的传热过程、水循环使用中水掺混比例进行了详尽的分析计算,并对节能效果进行了分析。结果表明,清洗管路系统热损较低,水掺混循环使用的节能效果明显。     

一步法制备石蜡微胶囊的中试研究及性能表征

采用一步法在100L反应釜内进行石蜡微胶囊制备的中试,表征了石蜡微胶囊的微胶囊化率、粒径和热性能,探讨了中试工艺对产品性能的影响。结果表明中试产品与实验室小试产品的性能基本接近。中试石蜡微胶囊的微胶囊化率为70％,平均粒径为54．0μm,相变范围为40～80℃,相变峰值和热焓分别为65℃,114J／g,分解温度达250℃。     

多轴数控机床的通用运动学综合空间误差模型

提出了一种适用任意结构多轴数控机床的新通用运动学综合空间误差模型。该模型包含了由于制造、安装、运动控制不精确和刀具、床身、工件热变形以及其它因素引起的初始位置误差与运动误差 ,反应了机床误差的实际变化规律 ,对机床工作区误差适时全补偿特别有效。为了发展该新型误差模型 ,运用了多体系统运动学理论和齐次变换矩阵。最后 ,利用所述建模理论和方法 ,给出了 3轴立式数控机床的空间误差模型表达式 ,并分析了其 36种误差成分的变化规律     

Optimal sample size allocation for tests with multiple levels of stress with extreme value regression

In this article, we discuss the optimal allocation problem in a multiple stress levels life‐testing experiment when an extreme value regression model is used for statistical analysis. We derive the maximum likelihood estimators, the Fisher information, and the asymptotic variance–covariance matrix of the maximum likelihood estimators. Three optimality criteria are defined and the optimal allocation of units for two‐ and k‐stress level situations are determined. We demonstrate the efficiency of the optimal allocation of units in a multiple stress levels life‐testing experiment by using real experimental situations discussed earlier by McCool and Nelson and Meeker. Monte Carlo simulations are used to show that the optimality results hold for small sample sizes as well. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

简谐外磁场环境下J-C模型的热力学纠缠

以简谐外磁场环境下的J-C模型为研究对象,从系统的哈密顿矩阵出发,通过计算模拟得出热力学纠缠度解析表达式。计算结果表明,对应于不同的外磁场强度,系统热力学纠缠度呈周期性余弦变化,但随环境温度升高快速衰减;在相同环境温度下,系统热力学纠缠度关于磁场强度左右不对称变化。     

水喷淋对建筑外立面火灾烟气向室内蔓延控制的研究

高层建筑外保温材料发生火灾后,研究着火层房间内的自动喷水灭火系统对火灾烟气向室内蔓延的控制效果,为高层建筑性能化防火设计提供理论支持。运用火灾动力学软件FDS模拟高层建筑外保温材料火灾,对比分析在不同喷射位置的自动喷水灭火系统作用下的室内平均CO浓度和温度等烟气特性参数。综合比较发现,将喷头置于窗上方向下喷淋能有效地降低室内平均CO浓度和平均温度。对于由高层建筑外保温材料引起的火灾,室内自动喷水灭火系统喷头相对于窗户的位置决定其对火灾烟气蔓延控制的效果。     

The impact of operational decisions on the design of salesforce incentives

When facing high levels of overstock inventories, firms often push their salesforce to work harder than usual to attract more demand, and one way to achieve that is to offer attractive incentives. However, most research on the optimal design of salesforce incentives ignores this dependency and assumes that operational decisions of production/inventory management are separable from design of salesforce incentives. We investigate this dependency in the problem of joint salesforce incentive design and inventory/production control. We develop a dynamic Principal‐Agent model with both Moral Hazard and Adverse Selection in which the principal is strategic and risk‐neutral but the agent is myopic and risk‐averse. We find the optimal joint incentive design and inventory control strategy, and demonstrate the impact of operational decisions on the design of a compensation package. The optimal strategy is characterized by a menu of inventory‐dependent salesforce compensation contracts. We show that the optimal compensation package depends highly on the operational decisions; when inventory levels are high, (a) the firm offers a more attractive contract and (b) the contract is effective in inducing the salesforce to work harder than usual. In contrast, when inventory levels are low, the firm can offer a less attractive compensation package, but still expect the salesforce to work hard enough. In addition, we show that although the inventory/production management and the design of salesforce compensation package are highly correlated, information acquisition through contract design allows the firm to implement traditional inventory control policies: a market‐based state‐dependent policy (with a constant base‐stock level when the inventory is low) that makes use of the extracted market condition from the agent is optimal. This work appears to be the first article on operations that addresses the important interplay between inventory/production control and salesforce compensation decisions in a dynamic setting. Our findings shed light on the effective integration of these two significant aspects for the successful operation of a firm. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 320–340, 2014