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451.
线性唯象传热规律下热机内可逆热经济学研究 总被引:1,自引:1,他引:0
对符合线性唯象传热规律(q∝Δ(T-1))的热机内可逆热经济学做了进一步研究,导出了在给定条件下Novikov热机的最优利润解析式,并得到了最优利润和相应的效率同其它参数间的关系. 相似文献
452.
任耀峰 《海军工程大学学报》2003,15(3):14-16
利用特殊半鞅的收敛定理和一般形式的Kronecker引理,给出了特殊半鞅和非负特殊半鞅强大数定律的一般形式,推广和完善了已有的结果. 相似文献
453.
《防务技术》2019,15(3):398-408
The mathematical model used to describe the detonation multi-physics phenomenon is usually given by highly coupled nonlinear partial differential equations. Numerical simulation and the computer aided engineering (CAE) technique has become the third pillar of detonation research, along with theory and experiment, due to the detonation phenomenon is difficult to explain by the theoretical analysis, and the cost required to accredit the reliability of detonation products is very high, even some physical experiments of detonation are impossible. The numerical simulation technique can solve these complex problems in the real situation repeatedly and reduce the design cost and time stunningly. But the reliability of numerical simulation software and the serviceability of the computational result seriously hinders the extension, application and the self-restoration of the simulation software, restricts its independently innovational ability. This article deals with the physical modeling, numerical simulation, and software development of detonation in a unified way. Verification and validation and uncertainty quantification (V&V&UQ) is an important approach in ensuring the credibility of the modeling and simulation of detonation. V&V of detonation is based on our independently developed detonation multi-physics software-LAD2D. We propose the verification method based on mathematical theory and program function as well as availability of its program execution. Validation is executed by comparing with the experiment data. At last, we propose the future prospect of numerical simulation software and the CAE technique, and we also pay attention to the research direction of V&V&UQ. 相似文献
454.
为使大口径舰炮制导炮弹在打击近岸机动目标的末制导段满足落角约束,现考虑自动驾驶仪动态特性,基于自适应RBF逼近网络与动态面滑模提出一种空间末制导律。构建空间弹目相对运动模型,通过带改进微分跟踪器的扩张状态观测器估计目标加速度。为零化视线角跟踪误差与视线角速率,采用自适应指数趋近律设计非奇异终端滑模动态面,并运用自适应RBF逼近网络削弱控制指令抖振。通过Lyapunov第二法证明了全系统中视线角跟踪误差与视线角速率均最终一致有界。仿真实验表明:该末制导律使制导炮弹在空间中打击具有不同机动形式的近岸目标时,均具备良好的末制导性能。 相似文献
455.
Jan Almäng 《Defence Studies》2019,19(2):189-204
It has frequently been observed in the literature on hybrid wars that there is a grey zone between peace and war, and that hybrid wars are conflicts which are not clear cases of war. In this paper, I attempt to illuminate this grey zone and the concept and nature of war from the philosophical discussions of vagueness and institutional facts. Vague terms are characterized by the fact that there is no non-arbitrary boundary between entities which lie in their extension, and entities which do not lie in their extension. I apply a theory of vagueness to notions such as “war” and “peace” and go on to suggest that the exact boundary for what counts as a war or not is arbitrary. However, the context in which the conflict occurs determines a range of possible locations for this boundary. The most important contextual parameter is in this respect how the parties to the conflict themselves conceptualize the conflict. I suggest that this can in various ways help us understand grey-zone conflicts. 相似文献
456.
为充分利用高超声速飞行器在俯冲段的质心运动与绕质心运动之间的耦合作用和飞行过程中的不确定性,基于模糊干扰观测器提出三维一体化制导与控制问题。根据飞行器的动力学方程以及飞行器-目标的视线角相对运动方程,推导出适用于倾斜转弯控制的一体化制导控制模型。针对模型中的不确定性采用模糊干扰观测器进行补偿,并使用块动态面方法设计一种一体化制导控制律。通过选取适当的李雅普诺夫函数证明闭环系统状态的一致毕竟有界性。仿真结果验证了该一体化制导控制方法的有效性和鲁棒性。 相似文献
457.
针对稀薄流域高超声速飞行器的气动加热问题,开展耦合数值计算研究。通过引入牛顿冷却定律,将直接模拟蒙特卡洛数值模拟方法与结构传热计算方法相结合,设计一种可对全机外形进行气动热和结构传热计算的高效松耦合方法,实现飞行器防热层结构材料温度分布特性的数值模拟。在以钝锥外形为例对直接模拟蒙特卡洛数值模拟程序进行验证的基础上,采用该方法对X37B轨道飞行器外形长时加热与结构传热过程进行数值模拟,给出结构温度及热流密度随飞行时间的变化规律。研究结果表明,设计的耦合计算方法能够模拟稀薄流域高超声速飞行器的气动加热及结构传热耦合过程,可为该类飞行器的气动热分析及热防护设计提供技术支持。 相似文献
458.
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460.
Rafael González-Val 《Defence and Peace Economics》2016,27(6):838-853
This paper analyses the statistical distribution of war sizes. Using a new methodology we find moderate support for a Pareto-type distribution (power law), considering data from different sources (COW and UCDP) and periods. A power law is a plausible model for the size distribution of a pool of all wars and a sample of wars in many years, although the log-normal distribution is a plausible alternative model that we cannot reject. The random growth of conflicts could generate both types of distribution. We study the growth rates of battle deaths and random growth cannot be rejected for most of the distribution, although the results also reveal a clear decreasing pattern; the growth of deaths declines faster if the number of initial deaths is greater. 相似文献