Nilay Tan&#x;k Argon  Sigrún Andradttir 《海军后勤学研究》2006,53(6):508-524

This paper studies a new steady‐state simulation output analysis method called replicated batch means in which a small number of replications are conducted and the observations in these replications are grouped into batches. This paper also introduces and compares methods for selecting the initial state of each replication. More specifically, we show that confidence intervals constructed by the replicated batch means method are valid for large batch sizes and derive expressions for the expected values and variances of the steady‐state mean and variance estimators for stationary processes and large sample sizes. We then use these expressions, analytical examples, and numerical experiments to compare the replicated batch means method with the standard batch means and multiple replications methods. The numerical results, which are obtained from an AR(1) process and a small, nearly‐decomposable Markov chain, show that the multiple replications method often gives confidence intervals with poorer coverage than the standard and replicated batch means methods and that the replicated batch means method, implemented with good choices of initialization method and number of replications, provides confidence interval coverages that range from being comparable with to being noticeably better than coverages obtained by the standard batch means method. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006  相似文献   

    

John A. Steele  Gábor J. Székely 《海军后勤学研究》2004,51(2):155-165

We show the existence of a unique analytic single parameter limiting survival function arising from the repeated composition of a coherent structure as the number of components tends to infinity. Examples include the repeated composition process of the bridge structure. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2004.  相似文献   

    

Bao U. Nguyen  Peter A. Smith  Du Nguyen 《海军后勤学研究》1997,44(7):687-697

We present an air-defense engagement model to counter an attack by multiple antiship missiles, assuming perfect kill assessment. In this model, the probability of shooting down all incoming missiles is maximized. A generating function is employed to produce an algorithm which is used to evaluate the outcomes. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 687–697, 1997  相似文献   

    

Emmanuelle Maitre  Pauline Lévy 《The Nonproliferation Review》2019,26(5-6):537-557

ABSTRACT

The making of the Treaty on the Prohibition of Nuclear Weapons (TPNW) has put Austria and its involvement in nuclear disarmament in the spotlight. This study highlights several factors that led Austria to become a prominent voice in nuclear-disarmament debates. First, its involvement dovetails with the emphasis on humanitarian disarmament it has promoted since the 1990s. Second, a strong antinuclear identity pervades Austrian society. This “nuclear allergy” combines antimilitarism inherited from the Cold War and, more broadly, an aversion to nuclear power, including for energy purposes. These two considerations form the background to the increased activism of the Austrian Foreign Ministry on nuclear disarmament in international fora. But, equally, Austria’s crusade for the TPNW can be attributed to the engagement of a small team of diplomats implementing personal as well as national preferences in favor of disarmament.  相似文献   

    

Stéphane Taillat  Frédérick Douzet 《Contemporary Security Policy》2019,40(3):362-367

Cyberspace experiences worrying trends that could have a negative impact on the international strategic landscape. The lack or erosion of norms and risky practices and behaviors could lead to greater uncertainty and thus greater instability. Set against a context of renewed competition between great powers, these developments are also tied to the strategic structure of cyberspace. This forum is devoted to discussing factors leading to stability or and instability.  相似文献   

    

Dmitrii Usanov  G.A. Guido Legemaate  Peter M. van de Ven  Rob D. van der Mei 《海军后勤学研究》2019,66(2):105-122

The effectiveness of a fire department is largely determined by its ability to respond to incidents in a timely manner. To do so, fire departments typically have fire stations spread evenly across the region, and dispatch the closest truck(s) whenever a new incident occurs. However, large gaps in coverage may arise in the case of a major incident that requires many nearby fire trucks over a long period of time, substantially increasing response times for emergencies that occur subsequently. We propose a heuristic for relocating idle trucks during a major incident in order to retain good coverage. This is done by solving a mathematical program that takes into account the location of the available fire trucks and the historic spatial distribution of incidents. This heuristic allows the user to balance the coverage and the number of truck movements. Using extensive simulation experiments we test the heuristic for the operations of the Fire Department of Amsterdam‐Amstelland, and compare it against three other benchmark strategies in a simulation fitted using 10 years of historical data. We demonstrate substantial improvement over the current relocation policy, and show that not relocating during major incidents may lead to a significant decrease in performance.  相似文献   

    

Eser Kırkızlar  Sigrún Andradóttir  Hayriye Ayhan 《海军后勤学研究》2010,57(6):563-582

We study the assignment of flexible servers to stations in tandem lines with service times that are not necessarily exponentially distributed. Our goal is to achieve optimal or near‐optimal throughput. For systems with infinite buffers, it is already known that the effective assignment of flexible servers is robust to the service time distributions. We provide analytical results for small systems and numerical results for larger systems that support the same conclusion for tandem lines with finite buffers. In the process, we propose server assignment heuristics that perform well for systems with different service time distributions. Our research suggests that policies known to be optimal or near‐optimal for Markovian systems are also likely to be effective when used to assign servers to tasks in non‐Markovian systems. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010  相似文献   

Perspectives on the AU and Nepad — An elite survey in seven African countries     

Hennie Kotzé 《Whitehall Papers》2013,80(1):115-141

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Peter Dahl Thruelsen 《Small Wars & Insurgencies》2013,24(4):619-643

This article argues that the debate on security sector reform (SSR) needs to be taken further by taking into consideration the fact that, even though the SSR concept was not originally developed as an element in stabilising states undergoing an insurgency, it is very much being used for exactly that. When conducting counterinsurgency with a focus on the creation of stability, the baseline will ultimately have to be security sector stabilisation (SSS) as a precondition for complete SSR implementation. However, the two must be connected to avoid them undermining each other. This is important if a comprehensive approach to programme implementation and especially sustainability is to guide the programme, and not just isolated ‘train and equip’ stand-alone projects that do not solve either the initial need for stabilisation or the long-term need for accountable security forces. Currently, in Afghanistan the surge for security by the international military is in danger of overtaking the other elements of the SSR, thereby undermining the primary end state and thus risking laying the wrong foundation for the long-term process of SSR.  相似文献   

    

Peter Dahl Thruelsen 《Small Wars & Insurgencies》2013,24(2):259-276

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