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591.
张承宗 《海军工程大学学报》1996,(1)
提出一种求解二阶线性椭圆形偏微分方程过值问题的新型复级数展开法,并用于求解二维各向异性稳态渗流问题,首先得到了各向异性稳态渗流矩形域、圆形域一般解析解,而且给出数值算例。 相似文献
592.
《防务技术》2022,18(9):1697-1714
To solve the problem of realizing autonomous aerial combat decision-making for unmanned combat aerial vehicles (UCAVs) rapidly and accurately in an uncertain environment, this paper proposes a decision-making method based on an improved deep reinforcement learning (DRL) algorithm: the multi-step double deep Q-network (MS-DDQN) algorithm. First, a six-degree-of-freedom UCAV model based on an aircraft control system is established on a simulation platform, and the situation assessment functions of the UCAV and its target are established by considering their angles, altitudes, environments, missile attack performances, and UCAV performance. By controlling the flight path angle, roll angle, and flight velocity, 27 common basic actions are designed. On this basis, aiming to overcome the defects of traditional DRL in terms of training speed and convergence speed, the improved MS-DDQN method is introduced to incorporate the final return value into the previous steps. Finally, the pre-training learning model is used as the starting point for the second learning model to simulate the UCAV aerial combat decision-making process based on the basic training method, which helps to shorten the training time and improve the learning efficiency. The improved DRL algorithm significantly accelerates the training speed and estimates the target value more accurately during training, and it can be applied to aerial combat decision-making. 相似文献
593.
PANG Zhihui 《国防科技》2018,39(1):047-052
韩国自20世纪90年代起开始考虑反导系统的构建以来,其反导政策经历了\"明确反对加入美国反导体系,自主构建韩国型导弹防御系统\"到\"强化韩美、韩美日反导合作,谋求实质上融入美国反导体系\"的显著调整与变化。韩国反导政策的演变与朝鲜核、导威胁的与日俱增、韩国自身反导能力的不足及美国的极力推动等因素密不可分。当前,韩国开始部署\"萨德\"末段高空区域反导系统,韩美反导合作日益深入,并向韩美日三边合作拓展,且取得了实质性的进展。韩国强化与美、日的反导联合,在军事、外交、安全方面引发了广泛影响。 相似文献
594.
Michael Evans 《Defense & Security Analysis》2019,35(2):133-146
The most effective way for the Western profession of arms to use history is to disavow the purism and narrow specialisation of today’s academia in favour of developing a contemporary approach to the subject. The latter aims to foster a range of applied diagnostic skills that transcend the temporal dimensions of past, present, and future. A contemporary approach to history for military professionals emphasises the use of inter-disciplinary war studies to enhance policy relevance. In any defense and security organisation, history must be usable in the sense of providing cognitive and interpretative skills for probing relationships between possibility and actuality, between experience and expectation, and between singularity and repetition. Using history to examine such dialectical interconnections is particularly valuable when military establishments confront their essential task of analyzing emerging trends in the future of war. 相似文献
595.
Tai Ming Cheung 《战略研究杂志》2016,39(5-6):728-761
ABSTRACTChina’s defense science, technology, and industrial system has been undergoing a far-reaching transformation over the past two decades and the single biggest factor behind this turnaround is the role of external technology and knowledge transfers and the defense industry’s improving ability to absorb these inputs and convert into localized output. China is pursuing an intensive campaign to obtain defense and dual-use civil–military foreign technology transfers using a wide variety of means, which is explored in this article. 相似文献
596.
We present a validation of a centralized feedback control law for robotic or partially robotic water craft whose task is to defend a harbor from an intruding fleet of water craft. Our work was motivated by the need to provide harbor defenses against hostile, possibly suicidal intruders, preferably using unmanned craft to limit potential casualties. Our feedback control law is a sample‐data receding horizon control law, which requires the solution of a complex max‐min problem at the start of each sample time. In developing this control law, we had to deal with three challenges. The first was to develop a max‐min problem that captures realistically the nature of the defense‐intrusion game. The second was to ensure the solution of this max‐min problem can be accomplished in a small fraction of the sample time that would be needed to control a possibly fast moving craft. The third, to which this article is dedicated, was to validate the effectiveness of our control law first through computer simulations pitting a computer against a computer or a computer against a human, then through the use of model hovercraft in a laboratory, and finally on the Chesapeake Bay, using Yard Patrol boats. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 247–259, 2016 相似文献
597.
Tamir Libel 《Defence Studies》2016,16(2):137-156
The paper’s main argument is that Israel’s security policy, which traditionally focused on defending its territorial integrity against regular Arab armed forces, was, by the 2010s, transformed into one that focuses on facing a variety of state- and non-state-based threats. Neo-realist explanations could neither account for the contested nature of the security debate during this period, nor the inconsistent evolution of the policy. The present study aims to solve this conundrum by introducing an alternative approach known as 4th generation strategic culture research. The paper is comprised of four parts. First, the origins and evolution of strategic culture are reviewed, with emphasis placed on the commonly accepted weaknesses that, to date, have prevented it from being used as a testable theoretical concept, and subsequently as an explanatory factor for security policy changes. The second part presents the “modernist constructivism” approach that bridges the gap between traditional constructivism and hypothesis-driven research design. Next, the paper introduces the emerging fourth generation in strategic culture literature, followed by a conceptual framework designed to resolve the inherent weaknesses of the more traditional approaches. Finally, this conceptual framework is applied to analyse the transformation of Israel’s security policy between 1982 and 2014. 相似文献
598.
Nicolas Groffman 《Defense & Security Analysis》2016,32(2):144-162
India and China both have powerful spy networks; completely different in their approaches to espionage; both effective against their perceived enemies. China focuses first on internal threats, on Taiwan and Hong Kong, and then the US and Japan. India’s defense policy focuses on Pakistan and internal terrorist threats, and then on China. In reality, however, when it comes to spying on each other, both China and India suffer from incompetence and apathy – which endangers both their own security and regional stability. This article looks at how they spy on each other, and asks why and how they need to improve. The narrative also touches upon some of the individuals who are waging the spy war, from India’s wily spymaster Ajit Doval down to junior Chinese agents such as Wang Qing and Pema Tsering. The two countries are not friends. They have the largest territorial dispute in the world on their hands, covering an area the size of North Korea, and they have large armies facing each other along 4000 kilometers of frontier. But they also lay claim to the world’s two oldest and richest civilizations, with a rich history of exchange, and now with a combined population of 2.6 billion people and more than a quarter of the world’s economic output. If they cooperated, they could solve many of the world’s problems; but if they lurch into conflict, the potential consequences are terrifying to contemplate. Unfortunately, despite their geographical closeness, they do not know much about each other. They have few cultural interchanges, little diplomacy, few trade missions. They do not watch each other’s films, read each other’s books or listen to each other’s music. Chinese tourists would rather fly to New Zealand for their holidays than cross the border to India, and Indian students would rather study in Europe than China. China and India are neighbors that barely talk to each other. Most significantly, they do not spy on each competently. For countries that do not interact socially, defensive understanding is important for security – but China prefers the glamor of facing up to its Pacific and other maritime rivals such as the US and Japan. India, for its part, does talk a great deal about the China threat, but its resources and expertise are wrapped up in controlling its security threat from Pakistan and the Islamic world. When China and India do try to spy on each other, it is often without the benefit of a long-term focus or understanding. India has some very skilled operatives within the Research and Analysis Wing, but few that specialize in China. China has an enormous pool of resources spread across several government departments, including the Ministry of Public Security, and also has extensive facilities and manpower in the Joint Staff Department of the Central Military Commission (the JSD) and the new Strategic Support Force (the SSF). However, China’s intelligence services generally behave as if India is not worth spying on. Given that the two countries do not have the cultural or political machinery in place to understand each other, espionage and intelligence gathering is vital to ensure that miscalculations do not take place. This has been apparent over the last few years in stand-offs in the Himalaya, as well as top-level suspicions on each side about a variety of subjects including terrorism, covert operations in Sri Lanka and Burma, and the two countries’ nuclear weapons programs. Both countries do occasionally make efforts in espionage against each other, especially during sensitive periods such as the mountain stand-offs of 2014 and 2013 and during policy developments in nuclear warfare. In this article the author looks at actual spying incidents between the two countries, their methodologies, their staff, their technical capabilities, and how the act of spying, which is usually viewed as intrinsically adversarial, can be a force for good. The article relies on interviews with actual participants in intelligence from both countries as well as extensive use of contemporary online sources, and secondary analysis by both military and academic experts from China, India and NATO countries. 相似文献
599.
Darrell Driver 《Defense & Security Analysis》2016,32(1):4-18
The US role in the North Atlantic Treaty Organization (NATO) Alliance is a 65-year history of retrenchment and renewal. When Washington has sought a retrenchment from the world, it traditionally increased burden sharing pressure on Europe to do more. During times of increased global ambition, the USA reaffirmed its traditional leadership role in the Alliance and its commitment to NATO effectiveness and relevance. This cycle of NATO retrenchment and renewal, however, is halting. Though the USA will continue to go through periods of relative increases and decreases in security policy ambition, signs point to a permanent defense and security retrenchment in Europe. Germany is the ally singularly capable of filling the resulting security gap. If NATO is to avoid the drift toward irrelevance many critics have predicted, Germany will need to cast off old inhibitions toward security and defense leadership. These trends and their implications for NATO's future are explored through historical case studies and the shifting contemporary security environment. 相似文献
600.
After 15 years of war in Afghanistan and Iraq, many now see ‘small-footprint’ security force assistance (SFA) – training, advising and equipping allied militaries – as an alternative to large US ground-force commitments. Yet, its actual military efficacy has been little studied. This paper seeks to fill this gap. We find important limitations on SFA’s military utility, stemming from agency problems arising from systematic interest misalignment between the US and its typical partners. SFA’s achievable upper bound is modest and attainable only if US policy is intrusive and conditional, which it rarely is. For SFA, small footprints will usually mean small payoffs. 相似文献