进入角约束下的载机变结构远距引导

针对一般导引律在载机远距引导中存在的问题,结合远距引导的需求,设计了远距引导的三维变结构导引律。该导引律具有较强自适应性,可以使载机以期望的进入角接近目标。仿真结果表明,载机在该导引律作用下,能以较小过载,平滑轨迹快速接近机动目标,并保证载机引导结束时占有有利的空中战术态势。     

An overview of conflict in Africa in 2014

Violent conflict escalated in Africa in 2014, with five sub-Saharan states – the Central African Republic (CAR), Nigeria, Somalia, South Sudan and Sudan – accounting for an estimated 75% of all conflict-related deaths on the continent. This paper provides an overview of the five major sub-Saharan African conflicts in 2014 and considers the underlying causes and dynamics in the Seleka/anti-Balaka conflict in the CAR, the Islamist threats of Boko Haram and al-Shabaab in Nigeria and Somalia, the civil war in South Sudan, and the long-running conflict between Sudan's government and southern and Darfuri rebels. The paper unpacks the general trends evident in these conflicts and the implications for the settlement thereof, including the targeting of civilians, ethnic and religious mobilisation and the state as epicentre of violence. The paper concludes with a brief look ahead to 2015.     

THE BRAZILIAN WAY

This article examines the positions held by Brazil under the administration of Luiz Inácio Lula da Silva (2003–present) on nuclear nonproliferation, arms control, and disarmament regimes and on contentious issues in those areas. Under Lula's government, Brazil has wanted to mediate between nuclear weapon and non-nuclear weapon states to consolidate its position as a strong negotiator and to benefit from the possible gains of this position in terms of greater participation in international institutions. It has also wanted to pressure nuclear weapon states to fulfill their disarmament obligations in order to reduce asymmetries in its relations with powerful nuclear weapon countries. At the same time, Brazil has tried to preserve its autonomy and flexibility to protect commercial secrets and preserve national security in relation to its own nuclear program.     

SDI,NATO, and the Social Composition Function

The strategic defense initiative (SDI) intends to renew the leadership of the USA on the western alliance. The initiative takes place in a period when a summation technology prevails for the aggregation of contributions of NATO allies. We investigate if SDI induces a shift in Hirshleifer’s social composition function. Panel data tests over the period 1970–1990 do not confirm any break toward a best-shot aggregator. SDI does not alter the core of deterrence. It is indeed a public good at the US level but not at the NATO level, where, it is one of the joint products of the alliance. We also investigate the lessons to be drawn for the current debates on ballistic defense.     

人车目标的自动识别

对单人、人群、机动车三类目标的特征进行了分析,找出了它们之间的不同之处,提出了对这三类目标进行分类识别的方法,并经现场检验,证明这种方法是有效的。     

Optimal FCFS allocation rules for periodic‐review assemble‐to‐order systems

In Assemble‐To‐Order (ATO) systems, situations may arise in which customer demand must be backlogged due to a shortage of some components, leaving available stock of other components unused. Such unused component stock is called remnant stock. Remnant stock is a consequence of both component ordering decisions and decisions regarding allocation of components to end‐product demand. In this article, we examine periodic‐review ATO systems under linear holding and backlogging costs with a component installation stock policy and a First‐Come‐First‐Served (FCFS) allocation policy. We show that the FCFS allocation policy decouples the problem of optimal component allocation over time into deterministic period‐by‐period optimal component allocation problems. We denote the optimal allocation of components to end‐product demand as multimatching. We solve the multi‐matching problem by an iterative algorithm. In addition, an approximation scheme for the joint replenishment and allocation optimization problem with both upper and lower bounds is proposed. Numerical experiments for base‐stock component replenishment policies show that under optimal base‐stock policies and optimal allocation, remnant stock holding costs must be taken into account. Finally, joint optimization incorporating optimal FCFS component allocation is valuable because it provides a benchmark against which heuristic methods can be compared. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 158–169, 2015     

The selection allocation problem

The Selection Allocation Problem (SAP) is a single period decision problem which involves selecting profit‐maximizing (or cost‐minimizing) activities from various distinct groups, and determining the volume of those activities. The activities in each group are selected subject to the availability of that group's resource, which is provided by either pooling or blending raw inputs from several potential sources. Imbedded in the decision process is the additional task of determining how much raw input is to be allocated to each group to form the resource for that group. Instances of this problem can be found in many different areas, such as in tool selection for flexible manufacturing systems, facility location, and funding for social services. Our goal in this paper is to identify and exploit special structures in the (SAP) and use those structures to develop an efficient solution procedure. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 707–725, 1999     

Fire truck relocation during major incidents

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.     

Optimal control policies for an inventory system with commitment lead time

We consider a firm which faces a Poisson customer demand and uses a base‐stock policy to replenish its inventories from an outside supplier with a fixed lead time. The firm can use a preorder strategy which allows the customers to place their orders before their actual need. The time from a customer's order until the date a product is actually needed is called commitment lead time. The firm pays a commitment cost which is strictly increasing and convex in the length of the commitment lead time. For such a system, we prove the optimality of bang‐bang and all‐or‐nothing policies for the commitment lead time and the base‐stock policy, respectively. We study the case where the commitment cost is linear in the length of the commitment lead time in detail. We show that there exists a unit commitment cost threshold which dictates the optimality of either a buy‐to‐order (BTO) or a buy‐to‐stock strategy. The unit commitment cost threshold is increasing in the unit holding and backordering costs and decreasing in the mean lead time demand. We determine the conditions on the unit commitment cost for profitability of the BTO strategy and study the case with a compound Poisson customer demand.     

Capitalism & the “new wars”: free markets and societal insecurity before and after the cold war, 1970–2013

Critics of globalisation suggest that growing free-market conditions generate anomie, leading ultimately to what some term ‘new wars’ and new insecurities. Others argue that liberal economies dissuade violence since people gain from peace. This study argues for a micro perspective that views predatory economic policies driving higher investment in rebellion-specific capital, such as shadow economic activity that easily translates into insurgency in weak-state settings. Investment in the shadows determines survivability against superior state forces, and survivability determines rebellion, by definition. Using civil war onset data from 1970 to 2013, as well as the Global Peace Index (GPI) and several of its individual components, which capture societal insecurity above and beyond the absence of armed violence, this study finds that countries that are more capitalistic have a lower risk of civil war and societal insecurity. The results are robust to alternative models, testing methods, and uphold when examining several relevant subcomponents of the index, such as internal conflict, violent crime, homicides, ease of access to small arms, and political instability. Surprisingly, democracy tends not to be associated with peace but associates with increased criminality whereas strong autocracy reduces it, suggesting that capitalism, more than democracy, associates with conditions favourable to societal security, independently of a country’s level of development.