聚碳硅烷先驱体制备SiC基复合材料的性能研究

本文以聚碳硅烷(PCS)为先驱体,SiC晶须,SiC微粉或C纤维为增强剂,热解转化制得SiC/SiC或C/SiC复合材料,研究其制备工艺过程对材料的力学和热物理性能的影响。结果表明:PCS在1300℃下转化为β-SiC微晶并将未烧结的增强剂网络在一起形成SiC/SiC或C/SiC复合材料。该SiC基复合材料具有较好的常温和高温机械强度,优异的耐热疲劳和抗热震性能,在1300℃空气中具有良好的抗氧化性。     

低能电子散射中的定域交换势(Ⅰ)电子被He，Ne和Ar原子的散射

文中利用自由电子气体近似(HFEGE)定域交换势和修正的半经典近似(MSCE)定域交换势,加上正交化方法(Orthogonalization technique),对能量在0.1～20eV的低能电子被He,Ne和Ar 原子的弹性散射过程进行了计算。其中靶原子的电荷分布以及入射电子和靶原子的静电作用利用原子的Roothaan-Hartree-Fock 波函数求出;相关和极化作用则用一个无参数的相关极化势近似表示。通过本文计算结果和严格计及交换作用的结果及实验数据相比较,对HFEGE和MSCE 交换势的准确性以及正交化过程对计算结果的影响进行了分析。     

Iran’s Nuclear Fatwa: Analysis of a Debate

For more than a decade, Iran has been referring to a fatwa issued by its Supreme Leader, Ali Khamenei, proscribing nuclear weapons. The fatwa, however, not only failed to influence the process that led to the resolution of Iran’s nuclear crisis, but also has been met with a good deal of skepticism. The most commonly held suspicions about the credibility of the fatwa can be summed up in five central questions: (1) Has the nuclear fatwa actually been issued? (2) Does the fatwa apply to all the aspects of nuclear weapons including their production, possession and use? (3) What is the juridical status of the fatwa? (4) Was the nuclear fatwa issued only to deceive other nations? (5) Is the fatwa really irreversible? This article tries to answer these questions by providing a chronological review of the fatwa and analyzing all the relevant statements by Khamenei. The analysis is conducted against the background of Islamic principles, Shi’a jurisprudence and the history of the Islamic Republic of Iran. The article concludes that the fatwa is a credible religious decree and could indeed contribute to the cause of nuclear disarmament.     

Reconsidering minimum deterrence in South Asia: Indian responses to Pakistan’s tactical nuclear weapons

India’s nuclear doctrine and posture has traditionally been shaped by minimum deterrence logic. This logic includes assumptions that possession of only a small retaliatory nuclear force generates sufficient deterrent effect against adversaries, and accordingly that development of limited nuclear warfighting concepts and platforms are unnecessary for national security. The recent emergence of Pakistan’s Nasr tactical nuclear missile platform has generated pressures on Indian minimum deterrence. This article analyzes Indian official and strategic elite responses to the Nasr challenge, including policy recommendations and attendant implications. It argues that India should continue to adhere to minimum deterrence, which serves as the most appropriate concept for Indian nuclear policy and best supports broader foreign and security policy objectives. However, the form through which Indian minimum deterrence is delivered must be rethought in light of this new stage of regional nuclear competition.     

Nuclear deterrence and cyber warfare: coexistence or competition?

Nuclear deterrence and cyber war seem almost antithetical in their respective intellectual pedigrees. Nuclear weapons are unique in their ability to create mass destruction in a short time. Information or “cyber” weapons, at least for the most part, aim at sowing confusion or mass disruption instead of widespread physical destruction. Nevertheless, there are some intersections between cyber and nuclear matters, and these have the potential to become troublesome for the future of nuclear deterrence. For example, cyber attacks might complicate the management of a nuclear crisis. As well, information attacks on command-control and communications systems might lead to a mistaken nuclear launch based on false warnings, to erroneous interpretations of data or to panic on account of feared information blackout. It is not inconceivable that future nuclear strike planning will include a preliminary wave of cyber strikes or at least a more protracted “preparation of the battlefield” by roaming through enemy networks to plant malware or map vulnerabilities.     

船用反应堆堆芯物理计算软件包的研制

基于船用反应堆结构特点与运行方式 ,通过对核电站大型机版堆芯物理计算软件的移植与修改 ,研制了微机版船用反应堆堆芯物理计算软件包 .可用于船用反应堆燃料组件参数及堆芯三维细网临界与燃耗的计算研究