Scheduling of depalletizing and truck loading operations in a food distribution system

This paper studies a scheduling problem arising in a beef distribution system where pallets of various types of beef products in the warehouse are first depalletized and then individual cases are loaded via conveyors to the trucks which deliver beef products to various customers. Given each customer's demand for each type of beef, the problem is to find a depalletizing and truck loading schedule that fills all the demands at a minimum total cost. We first show that the general problem where there are multiple trucks and each truck covers multiple customers is strongly NP‐hard. Then we propose polynomial‐time algorithms for the case where there are multiple trucks, each covering only one customer, and the case where there is only one truck covering multiple customers. We also develop an optimal dynamic programming algorithm and a heuristic for solving the general problem. By comparing to the optimal solutions generated by the dynamic programming algorithm, the heuristic is shown to be capable of generating near optimal solutions quickly. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003     

基于事故树分析法的火灾致灾因素分析

基于事故树分析法对火灾中的致灾因素进行分析，通过对近十年51起重、特大火灾进行归纳、统计，利用火灾调查理论知识与事故树相结合，将火灾中的致灾因素分为起火原因、火灾中人员伤亡因素、造成财产损失原因进行分类统计，并利用最小割集和最小径集，计算出顶上事件的发生概率。最后对事故树进行分析讨论，找出避免顶上事件发生的措施，得出减少或消除火灾致灾的对策，为做好重、特大火灾的预防工作提供了参考。     

The truck assignment problem

Let us consider the following problem: A group of cement factories produces several types of cement, but each factory produces only one type. There is also a group of purchasers and each purchaser may need several types of cement. The amounts supplied and the demands are assumed to be known for each cement factory and each purchaser. Each cement factory has several trucks, but there is only one dispatcher for ail of the trucks from all of the factories. It is assumed that the entire lcad of each truck is for one purchaser only. A truck begins its workday by leaving its base depot loaded and ends its day by returning to it empty. During the day it may be required to transport cement from any of the cement factories. The distances from various factories to individual purchasers are known. The problem to be solved is that of finding a truck schedule such that cement in the needed quantities is delivered daily to the individual purchasers and in such a manner that the total truck-kilometers traveled will be as small as possible. This paper presents the method of solution, though the assumption of an 8-hour workday may not be met. On the other hand, there are methods developed for effecting a variety of cyclic routings which can be used to lend considerable flexibility to the schedules.     

Did the Panamanian Defense Forces conduct infiltration operations at the Arraijan Tank Farm in 1988?

This article reviews the circumstances surrounding a relatively obscure and almost forgotten US Marine Corps and Army security enhancement operation undertaken in Panama that commenced in early April of 1988. Marines were sent to Panama to protect oil and ammunition storage facilities from potential saboteurs. By April 1989 they had reported sighting armed, uniformed intruders on at least 43 occasions and receiving gunfire or discharging their own weapons during 16 incidents. Yet despite the repeated barrages of small arms fire over the course of a year, they failed to recover enemy ammunition, bodies or body parts and their own equipment and positions displayed no signs of suffering from hostile fire. This article analyzes the events from the point of view of a veteran of the operation and highlights the role that psychological operations may have played in generating the situation.     

‘Troops were then forced to fire’: British army crowd control in Palestine,November 1945

In November 1945, British army shooting during street riots and search operations in Palestine resulted in the death of 13 Jews and the injuring of dozens. The most costly in casualties caused by army fire during the whole Jewish insurgency, these incidents have nevertheless not received detailed attention in literature on the British army's counterinsurgency campaign in postwar Palestine. This article outlines British military use of firepower to control civilian crowds and the difficulties involved during these incidents, contributing to the debate on the army's principal of ‘minimum force’. It also highlights the serious problem of legitimizing opening of fire on unarmed protestors, epitomized in the army's fabricated account justifying shooting at a large crowd rushing a military cordon at Givat Hayim.     

Success and Failure in Terrorist Investigations: Research and Lessons from Northern Ireland

Police investigations of terrorist incidents are rarely straightforward. This paper reports the findings of research that looked at low-level paramilitary attacks in Northern Ireland which have taken place during the ceasefire era. Of 500 incidents studied, 28 were followed by the arrest of suspects. The study examines what factors were important for linking later arrests with other features of the incident. These results are discussed in terms of the wider implications for the successful investigation of paramilitary offences and in terms of the specific implications for investigative policing within Northern Ireland.     

消防部队处置炭疽芽孢杆菌袭击事件技术方案探讨

对消防部队处置炭疽芽孢杆菌袭击事件的防护技术、现场侦查方法、警戒隔离、样品采集、快速检测技术、洗消技术及其注意事项进行了论述，对消防部队处置此类及类似事故具有一定的指导意义。     

基于ExtendSim的高炮群作战效能仿真分析

构建了高炮部队抗空袭作战仿真流程,并在特定作战条件下基于ExtendSim建立了高炮群雷达诸元法抗击敌空袭目标的作战仿真模型,对火控雷达组网工作模式下的扇形和线性配置的高炮群作战效能进行了仿真分析,结果表明在火控雷达组网模式下,高炮群整体探测范围增大,作战反应时间延长,提高了部队作战效能。     

A learning tabu search for a truck allocation problem with linear and nonlinear cost components

The two‐level problem studied in this article consists of optimizing the refueling costs of a fleet of locomotives over a railway network. The goal consists of determining: (1) the number of refueling trucks contracted for each yard (truck assignment problem denoted TAP) and (2) the refueling plan of each locomotive (fuel distribution problem denoted FDP). As the FDP can be solved efficiently with existing methods, the focus is put on the TAP only. In a first version of the problem (denoted (P1)), various linear costs (e.g., fuel, fixed cost associated with each refueling, weekly operating costs of trucks) have to be minimized while satisfying a set of constraints (e.g., limited capacities of the locomotives and the trucks). In contrast with the existing literature on this problem, two types of nonlinear cost components will also be considered, based on the following ideas: (1) if several trucks from the same fuel supplier are contracted for the same yard, the supplier is likely to propose discounted prices for that yard (Problem (P2)); (2) if a train stops too often on its route, a penalty is incurred, which represents the dissatisfaction of the clients (Problem (P3)). Even if exact methods based on a mixed integer linear program formulation are available for (P1), they are not appropriate anymore to tackle (P2) and (P3). Various methods are proposed for the TAP: a descent local search, a tabu search, and a learning tabu search (LTS). The latter is a new type of local search algorithm. It involves a learning process relying on a trail system, and it can be applied to any combinatorial optimization problem. Results are reported and discussed for a large set of instances (for (P1), (P2), and (P3)), and show the good performance of LTS. © 2014 Wiley Periodicals, Inc. 62:32–45, 2015     

The Amritsar Massacre and the minimum force debate

This article re-examines one of the most infamous incidents in British imperial history: the Amritsar Massacre of 1919, and analyses it within the context of the British Army's minimum force philosophy. The massacre has long been regarded as the most catastrophic failure of minimum force in the history of the British Army. This article reconsiders the arguments over the shooting at Amritsar and the role of Brigadier-General Reginald Dyer, and questions the accepted view that the massacre was such a failure of minimum force. It argues that the circumstances surrounding the massacre must be understood before judging the incident and given these factors it is possible to see it within a minimum force framework.     

Heuristic modeling of supply availabilities in large networks

The objective of this article is to describe heuristic solutions to the problem of modeling inventories at each node of a large network in the context of a computer simulation model of that network. The heuristic solutions are compared with the mathematical solution which is too unwieldy for use in a simulation model. The Weibull cumulative distribution is used as an approximation for the heuristic models. We question whether the good performance of the Weibull is coincidence or perhaps mathematically justifiable.     

The Value of Respect: What Does it Mean for an Army?

The Australian Army has adopted “respect” as a new addition to the existing trio of values, “courage, initiative and teamwork.” This article explores what respect may mean as an army value. The significance of respect surrounding two incidents involving Australian Defence Force personnel while on duty in Afghanistan is considered. The first is the so-called “green on blue” attack by an Afghan National Army soldier killing three Australian soldiers on 29 August 2012. The second concerns allegations of mutilation of suspected Afghan insurgents’ corpses by soldiers attached to an Australian Special Forces Unit on 28 April 2013. The incidents have resulted in internal military investigations: in the second incident, with a view to possible prosecution for breach of the law of armed conflict and related disciplinary offences; and in the case of the green on blue attack, leading to a civilian coronial inquest. This article discusses the training and modelling of behaviour required to instil such a value as respect.     

浅析储油罐安全容量的确定计算

由于油料具有热膨胀性，在运输和储存期间，如果油罐装油超过安全容量，当温度升高时，罐内油料体积膨胀，就可能导致溢油事故的发生，不仅造成油料数量的损失，甚至会引发火灾事故。正确确定不同油罐的安全容量，对油料的安全具有重要意义。文章阐述了油罐安全容量的概念，分析了安全容量计算不准确可能造成的危害，提出了油罐安全容量的计算方法。     

The management of security incidents by private security

This article is about the management of security incidents in organisations and companies which are under the protection of private security personnel, whether in-house or contracted. Incidents can be defined as accidental or anecdotal (bird flies into a camera) to a violation of law or company policy. Managing security incidents is one of the key functions of a private security service provider. The purpose of this study is to explore the management of security incidents and the information related thereto, identify shortcomings and find solutions for managing these shortcomings. Interviews were used to gain insight from personnel within the private and government sectors which are served by the private security industry. It was found that security incidents are handled in a routine way by organisations from the different sectors. One major shortcoming is that security incidents and the information related thereto are not managed by security service providers according to an operational framework or model with the required infrastructure and resources. The significance of this study is for security incidents to be managed correctly, so that the information related thereto may be captured accurately, analysed and used proactively and reactively to improve physical protection systems, develop preventative strategies and provide actionable information products in order to reduce crime, increase detection rates and prevent losses.     

Place–time correlation of robbery incidents in metropolitan Lagos: a Mantel index analysis

This article investigates the correlation of space and time in the clustering of robbery incidents in metropolitan Lagos. Analysis was carried out on 781 selected robbery incidents in 2013. Using the Mantel index to correlate place and time intervals for pairs of robbery incidents, the results show that robberies are respectively concentrated in residential areas, transport nodes and public places, peaking at midnight during weekdays. The results further show that this concentration is most likely greater than what would be expected on the basis of a chance distribution. The study concludes that various factors may exist which cause clusters of robberies to occur in these places at these times.     

Complexity and workload considerations in product mix decisions under the theory of constraints

The literature on the product mix decision (or master production scheduling) under the Theory of Constraints (TOC), which was developed in the past two decades, has addressed this problem as a static operational decision. Consequently, the developed solution techniques do not consider the system's dynamism and the associated challenges arising from the complexity of operations during the implementation of master production schedules. This paper aims to address this gap by developing a new heuristic approach for master production scheduling under the TOC philosophy that considers the main operational factors that influence actual throughput after implementation of the detailed schedule. We examine the validity of the proposed heuristic by comparison to Integer Linear Programming and two heuristics in a wide range of scenarios using simulation modelling. Statistical analyses indicate that the new algorithm leads to significantly enhanced performance during implementation for problems with setup times. The findings show that the bottleneck identification approach in current methods in the TOC literature is not effective and accurate for complex operations in real‐world job shop systems. This study contributes to the literature on master production scheduling and product mix decisions by enhancing the likelihood of achieving anticipated throughput during the implementation of the detailed schedule. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 357–369, 2015     

计算流体动力学在隧道安全中的应用

总结分析了近年国内外重大隧道火灾事故，简述了隧道火灾的特点、危害性及其烟气控制方法，回顾了国内外对隧道火灾的研究现状。着重介绍了计算流体动力学（CFD）在隧道通风安全中的应用。同时总结了国内外在研究隧道火灾方面应用CFD模拟所作的一些基本工作，并描述近来在隧道安全工程的一些典型应用。     

A sequential partial information bomber-defender shooting problem

A bomber carrying homogenous weapons sequentially engages ground targets capable of retaliation. Upon reaching a target, the bomber may fire a weapon at it. If the target survives the direct fire, it can either return fire or choose to hold fire (play dead). If the former occurs, the bomber is immediately made aware that the target is alive. If no return fire is seen, the true status of the target is unknown to the bomber. After the current engagement, the bomber, if still alive, can either re-engage the same target or move on to the next target in the sequence. The bomber seeks to maximize the expected cumulative damage it can inflict on the targets. We solve the perfect and partial information problems, where a target always fires back and sometimes fires back respectively using stochastic dynamic programming. The perfect information scenario yields an appealing threshold based bombing policy. Indeed, the marginal future reward is the threshold at which the control policy switches and furthermore, the threshold is monotonic decreasing with the number of weapons left with the bomber and monotonic nondecreasing with the number of targets left in the mission. For the partial information scenario, we show via a counterexample that the marginal future reward is not the threshold at which the control switches. In light of the negative result, we provide an appealing threshold based heuristic instead. Finally, we address the partial information game, where the target can choose to fire back and establish the Nash equilibrium strategies for a representative two target scenario.     

工业企业火灾爆炸量化分析方法应用探讨

运用工业企业火灾爆炸量化分析方法对发生在韩国的一起液化石油气充装站火灾爆炸事故进行了量化分析.结果表明在沸腾液体扩展蒸气爆炸发生前的21 min时间内约有6.0t的丁烷泄漏并参与到池火燃烧中;丁烷槽车胶管与丁烷地下储罐管线之间的不良连接是导致丁烷泄漏的原因,其有效泄漏直径为27 mm;参与火球燃烧的丁烷为3.7t,约占沸腾液体扩展蒸气爆炸发生时槽车内剩余丁烷的62％;参与火球燃烧的丙烷为8.0t,约占丙烷槽车全部装载量的53％.     

An attacker‐defender model for analyzing the vulnerability of initial attack in wildfire suppression

Wildfire managers use initial attack (IA) to control wildfires before they grow large and become difficult to suppress. Although the majority of wildfire incidents are contained by IA, the small percentage of fires that escape IA causes most of the damage. Therefore, planning a successful IA is very important. In this article, we study the vulnerability of IA in wildfire suppression using an attacker‐defender Stackelberg model. The attacker's objective is to coordinate the simultaneous ignition of fires at various points in a landscape to maximize the number of fires that cannot be contained by IA. The defender's objective is to optimally dispatch suppression resources from multiple fire stations located across the landscape to minimize the number of wildfires not contained by IA. We use a decomposition algorithm to solve the model and apply the model on a test case landscape. We also investigate the impact of delay in the response, the fire growth rate, the amount of suppression resources, and the locations of fire stations on the success of IA.