NUCLEAR BOMB SQUAD

Defusing Armageddon: Inside NEST, America's Secret Nuclear Bomb Squad, by Jeffrey T. Richelson. W.W. Norton & Company, 2009. 318 pages, $27.95.     

一种纯方位跟踪中的自适应滤波算法

针对纯方位被动目标跟踪中扩展卡尔曼滤波算法易发散的不足,提出了一种自适应的改进算法。该算法利用极大后验噪声估计器Sage-Husa对虚拟观测噪声进行实时在线估计,动态补偿线性化带来的误差。算法的对比仿真分析结果表明,AEKF较之EKF滤波效果有所改善,增强了稳定性,提高了精度,为水下纯方位被动目标跟踪的实现提供一种新的方法。     

自适应平方根无迹滤波的雷达组网状态估计算法

从最小方差的角度分析了雷达组网无迹滤波(Unscented Filter,UF)状态估计的统计学本质,并且针对UF的Cholesky分解遇到非半正定矩阵容易发散、不准确滤波初值造成滤波发散以及异常扰动影响滤波效果等问题,提出将自适应平方根无迹滤波(Adaptive Square Root Unscented Filter,ASQUF)用于雷达组网状态估计,结合合理的滤波初始化策略,提高了UF的工程可用性。仿真验证表明,提出的ASRUF算法用于雷达组网空域目标状态估计时,初始化平稳无波动,工程可用性好,状态估计精度高,明显优于扩展卡尔曼滤波(Extended Kalman Filter,EKF)算法。     

Lines in the sand: the use and misuse of red lines

This article explores series of “red lines” issued over the years by the USA and Israel toward Iran and Syria. It argues that the effectiveness of inflexible “red lines” in an environment that is given to rapid change is doubtful. They provide an adversary with the ability to determine when the deterring party will act and when they will not, a situation that is often undesirable. Moreover, their inflexible nature on the one hand opens the doors for circumvention while technically staying within their parameters. On the other hand, a strategy of more ambiguous “red lines” that allow flexibility in choosing the time, intensity, and nature of the response could also achieve a considerable deterrent effect, provided that they do not remain mere bluffs.     

基于渐消因子的双机协同机动目标定位

传统的双机协同组网目标定位模型中,滤波方法大多为交互式多模型算法。交互式多模型算法的缺陷为需要目标机动先验模型,且模型个数的选择难以同时满足工程上关于跟踪精度和算法复杂性的要求。通过引入渐消因子,实时自适应校正机动目标的状态估计偏差,有效降低了目标运动先验模型对滤波的影响,提高了系统的机动处理能力和模型的工程实用性。     

India's Evolving Nuclear Posture

This article analyzes India's nuclear doctrine, finding it to be critically flawed and inimical to strategic stability in South Asia. In pursuing an ambitious triad of nuclear forces, India is straying from the sensible course it charted after going overtly nuclear in 1998. In doing so, it is exacerbating the triangular nuclear dilemma stemming from India's simultaneous rivalries with China and Pakistan. Strategic instability is compounded by India's pursuit of conventional “proactive strategy options,” which have the potential to lead to uncontrollable nuclear escalation on the subcontinent. New Delhi should reaffirm and redefine its doctrine of minimum credible nuclear deterrence, based on small nuclear forces with sufficient redundancy and diversity to deter a first strike by either China or Pakistan. It should also reinvigorate its nuclear diplomacy and assume a leadership role in the evolving global nuclear weapon regime.     

The Requirements of Nuclear Stability in South Asia

While recent history arguably demonstrates a high level of nuclear stability in South Asia, this article argues that this stability has historically been a function of India's relative weakness. It argues that, as India becomes stronger, attention must be paid to the technical and political requirements of nuclear stability: the reliability of weapons and command and control and the political conditions that underpin stable relations between nuclear-armed states. It concludes by recommending the United States aim to modify the perceptions of regional elites about their various intentions and decision-making processes and the role of the United States as crisis manager.     

China's Nuclear Forces and Their Significance to India

The Indian nuclear program is a response to a perceived politico-strategic threat from China as opposed to a military-operational one that New Delhi began after perceiving an “ultimatum” from China in 1965. Consequently, India is in the process of acquiring an assured second-strike capability vis-à-vis China to meet the requirements of general deterrence. While India has always been concerned about the Sino-Pakistani nuclear/missile nexus, China has become wary of the growing military ties between the United States and India in recent years, especially because of the military implications of the US-India civil nuclear deal. Given the growing conventional military gap between the two states, India is not lowering its nuclear threshold to meet the Chinese conventional challenge. Instead, India is upgrading its conventional military strategy from dissuasion to deterrence against China. While the overall Sino-Indian nuclear relationship is stable, it will be challenged as China acquires advanced conventional weapons that blur the distinction between conventional and nuclear conflict.     

Pakistan's Evolving Nuclear Weapon Posture

This essay provides an overview of the ongoing quantitative and qualitative changes in Pakistan's nuclear arsenal and their impact on deterrence stability vis-à-vis India. Prominent among these trends is a major expansion in fissile material production that enables the manufacture of lighter and more compact warheads optimized for battlefield missions; the development of cruise missiles and shorter-range ballistic missiles possessing dual-use capabilities; and a greater emphasis in doctrinal pronouncements on the need for strike options geared to all levels of conflict. Although these trends pose problematic ramifications for the risks of unauthorized and inadvertent escalation, deterrence stability in South Asia is not as precarious as many observers fear. The challenges of fashioning a robust nuclear peace between India and Pakistan cannot be lightly dismissed, however, and policy makers would do well to undertake some reinforcing measures.