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31.
本文在梁的纯弯曲损伤基本假设条件下,导出了弯曲损伤的基本方程,与Kachanov的材料刚度劣化(受载横截面积减小)定义拉伸损伤变量类似,以梁的弯曲刚度劣化(惯性矩减小)定义弯曲损伤变量,从而建立了与Kachanov拉伸损伤模型相类似的梁的各向同性弯曲损伤模型。最后,以受蠕变纯弯曲梁为实例进行了损伤分析,在一次近似条件下,该弯曲损伤模型的材料常数可由Kachanov拉伸损伤模型的材料常数确定,且所得计算结果与Kachanov拉伸损伤模型所得结果比较吻和,表明该弯曲损伤模型是合理适用的。  相似文献   
32.
食指[1]诗歌的主题是苦难和宿命,其中最动人的部分是纯朴而高贵的诗质,他忠实于内心的呼唤,表达个体生命体验和对未来的坚定信仰;对苦难和宿命的抗争,建立在美好天性和本质向善的道德信仰之上,诗成为生命的内在抒发。与之相适应,是他的诗歌传统形式美的内核,以节制和内敛的美学追求,更新了一个时代的情感表达方式。  相似文献   
33.
小灵巧炸弹是一种采用倾斜转弯(BTT)控制方式的小型面对称电视制导航空弹药,在实际飞行中必须确保其导引头框架角不超出可用范围。针对上述问题,根据时变偏置比例导引的思想,在三维空间中设计视线角速率偏置项,通过姿态角时变修正实现框架角约束,提出了一种带导引头框架角约束的三维纯比例导引律。仿真结果表明该方法在保证小灵巧炸弹战技指标要求的同时有效减少了框架角需求。  相似文献   
34.
With the burgeoning influence of emerging markets in Asia, a tectonic shift is taking place in the global security landscape. Asian states are concomitantly arming as their economic clout grows. In light of these developments, security analysts would benefit from a formal means of placing these arms acquisitions in a structural context. Are arms acquisitions on par with the expectations of Asian states, given their structural dispositions, or are recent acquisitions beyond anticipated levels? By using a dynamic panel regression of 187 states from 1950 to 2011, this research predicts arms import volume using the degree of interstate arms linkages, the size of a state's military, and its level of economic development. The technique offers analysts a formal means of distinguishing orthodox behavior in importing conventional weapons from extraneous security motivations. The article concludes by generating near-term forecasts of Asian arms imports and discussing the implications of the technique.  相似文献   
35.
面向装备维修保障系统的多分辨率建模问题,提出了一种装备维修模型的聚合方法,为装备维修保障系统模型的聚合研究提供了一种新的思路。该方法通过聚合故障输入和推理维修状态实现维修模型的聚合。最后通过基于MATLAB的仿真实验验证了该方法的可行性。通过实例验证可以看出,该方法缩短了仿真时间,减少了复杂系统底层建模的工作量。  相似文献   
36.
A number of results pertaining to preservation of aging properties (IFR, IFRA etc.) under various shock models are available in the literature. Our aim in this paper is to examine in the same spirit, the preservation of unimodality under various shock models. For example, it is proved that in a non-homogeneous Poisson shock model if {pk}K≥0, the sequence of probabilities with which the device fails on the kth shock, is unimodal then under some suitable conditions on the mean value function Λ (t), the corresponding survival function is also unimodal. The other shock models under which the preservation of unimodality is considered in this paper are pure birth shock model and a more general shock model in which shocks occur according to a general counting process. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 952–957, 1999  相似文献   
37.
ABSTRACT

The legitimate authority principle has become reduced to the issue of state authority. In its current formulation, the state has the sole authority to wage war, and because non-state actors, by their very definition, cannot satisfy this principle, their use of force is inherently unethical. This does not reflect the reality that non-state actors are increasingly engaging in the use of force, sometimes legitimately. As a result, the legitimate authority principle can and should look beyond the state. This article navigates a terrain in which non-state actors engage in the use of force, and in which revisionist just war thinking proposes that the concept of legitimate authority is irrelevant to thinking about the ethics of war. It proposes a principled approach to the inclusion of some non-state actors under the rubric of legitimate authority. This approach draws upon the historical development of the legitimate authority principle and incorporates the factors important to early writers on the subject.  相似文献   
38.
地址随机化是一种针对控制流劫持漏洞的防御机制。已有的漏洞自动分析与利用技术缺少对地址随机化机制影响的分析,导致生成的测试用例在实际环境中的运行效果受到极大限制。针对地址随机化的缺陷及其绕过技术的特点,提出了一种地址随机化脆弱性分析方法。该方法使用有限状态机描述程序运行路径中各关键节点的状态;针对常见的内存泄漏与控制流劫持场景建立约束条件;通过求解内存泄漏状态约束与控制流劫持状态约束的兼容性,分析地址随机化机制在特定场景下的脆弱性。实验结果表明,该方法可有效检测通过内存泄漏导致的地址随机化绕过及控制流劫持攻击,实现自动化的地址随机化脆弱性分析,提高针对软件安全性分析的效率。  相似文献   
39.
This article traces the evolution of the EU strategic reflection which culminated in the publication of the EU Global Strategy (EUGS) in June 2016. It explains the choices made by EU High Representative Federica Mogherini over this time period—including both the initial strategic assessment and the final EUGS. It provides a behind the scenes view on the players, the organization and the methods of work used to produce a strategic vision for the EU’s role in the world.  相似文献   
40.
基于纯纠缠态的量子安全直接通信协议   总被引:1,自引:0,他引:1  
基于纯纠缠态,提出一种量子安全直接通信协议.通信方利用decoy光子来检测窃听.在保证量子信道的安全后,发送方通过控制非操作和von Neumarm测量将秘密消息编码在纯纠缠态上并发送给接收方.由于所有的纯纠缠态都用于传输秘密消息,该协议具有较高的量子比特效率.就实验的可行性来说,该协议可以用当前的技术实现.此外,该协议在噪声量子信道中也是安全的.  相似文献   
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