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81.
We introduce and develop models for a physical goods storage system based on the 15‐puzzle, a classic children's game in which 15 numbered tiles slide within a 4 × 4 grid. The objective of the game is to arrange the tiles in numerical sequence, starting from a random arrangement. For our purposes, the tiles represent totes, pallets, or even containers that must be stored very densely, and the objective is to maneuver items to an input–output point for retrieval or processing. We develop analytical results for storage configurations having a single empty location (as in the game) and experimental results for configurations with multiple empty locations. Designs with many empty locations can be made to form aisles, allowing us to compare puzzle‐based designs with traditional aisle‐based designs found in warehousing systems. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007 相似文献
82.
The ability to effectively match supply and demand under uncertainty can result in significant revenue benefits in the airline industry. We study the benefits of a Demand Driven Swapping (DDS) approach that takes advantage of the flexibilities in the system and dynamically swaps aircraft as departures near and more accurate demand information is obtained. We analyze the effectiveness of different DDS strategies, characterized by their frequency (how often the swapping decision is revised), in hedging against demand uncertainty. Swapping aircraft several weeks prior to departures will not cause much disturbance to revenue management and operations, but will be based on highly uncertain demands. On the other hand, revising the swapping decision later will decrease the possibility of bad swaps, but at a higher cost of disrupting airport services and operations. Our objective is to provide guidelines on how the flexible (swappable) capacity should be managed in the system. We study analytical models to gain insights into the critical parameters that affect the revenue benefits of the different swapping strategies. Our study determines the conditions under which each of the different DDS strategies is effective. We complement our analysis by testing the proposed DDS strategies on a set of flight legs, using data obtained from United Airlines. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004. 相似文献
83.
This paper studies capacity expansions for a production facility that faces uncertain customer demand for a single product family. The capacity of the facility is modeled in three tiers, as follows. The first tier consists of a set of upper bounds on production that correspond to different resource types (e.g., machine types, categories of manpower, etc.). These upper bounds are augmented in increments of fixed size (e.g., by purchasing machines of standard types). There is a second‐tier resource that constrains the first‐tier bounds (e.g., clean room floor space). The third‐tier resource bounds the availability of the second‐tier resource (e.g., the total floor space enclosed by the building, land, etc.). The second and third‐tier resources are expanded at various times in various amounts. The cost of capacity expansion at each tier has both fixed and proportional elements. The lost sales cost is used as a measure for the level of customer service. The paper presents a polynomial time algorithm (FIFEX) to minimize the total cost by computing optimal expansion times and amounts for all three types of capacity jointly. It accommodates positive lead times for each type. Demand is assumed to be nondecreasing in a “weak” sense. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2004. 相似文献
84.
Kenneth R. Baker 《海军后勤学研究》1999,46(8):978-991
This paper examines heuristic solution procedures for scheduling jobs on a single machine to minimize the maximum lateness in the presence of setup times between different job families. It reviews the state of knowledge about the solution of this problem, which is known to be difficult to solve in general, and examines natural solution approaches derived from some of the underlying theory. The emphasis is on the design and computational evaluation of new heuristic procedures. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 978–991, 1999 相似文献
85.
State‐level newborn screening allows for early treatment of genetic disorders, which can substantially improve health outcomes for newborns. As the cost of genetic testing decreases, it is becoming an essential part of newborn screening. A genetic disorder can be caused by many mutation variants; therefore, an important decision is to determine which variants to search for (ie, the panel design), under a testing budget. The frequency of variants that cause a disorder and the incidence of the disorder vary by racial/ethnic group. Consequently, it is important to consider equity issues in panel design, so as to reduce disparities among different groups. We study the panel design problem using cystic fibrosis (CF) as a model disorder, considering the trade‐offs between equity and accuracy, under a limited budget. Most states use a genetic test in their CF screening protocol, but panel designs vary, and, due to cost, no state's panel includes all CF‐causing variants. We develop models that design equitable genetic testing panels, and compare them with panels that maximize sensitivity in the general population. Our case study, based on realistic CF data, highlights the value of equitable panels and provides important insight for newborn screening practices. 相似文献
86.
Joanna R.Hall Olivia Matthews Timothy N.Volonakis Eric Liggins Karl P.Lymer Roland Baddeley Innes C.Cuthill Nicholas E.Scott-Samuel 《防务技术》2021,17(6):1833-1839
The human visual system is still an important factor in military warfare; military personnel receive training on effective search strategies, and camouflage that can effectively conceal objects and personnel is a key component of a successful integrated survivability strategy. Previous methods of camouflage assessment have, amongst others, used psychophysics to generate distinctiveness metrics. However, the population from which the human observers are drawn is often not well defined, or necessarily appropriate. In this experiment we designed a new platform for testing multiple patterns based on a camouflaged object detection task, and investigate whether trained military observers perform better than civilians. We use a two-alternative forced choice paradigm, with participants searching images of woodland for a replica military helmet displaying Olive Green, Multi Terrain Pattern, US Marine Pattern or, as a conspicuous control, UN Peacekeeper Blue. Our data show that there is no difference in detection performance between the two observer groups but that there are clear differences in the effectiveness of the different helmet colour patterns in a temperate woodland environment. We conclude that when tasks involve very short stimulus presentation times, task-specific training has little effect on the success of target detection and thus this paradigm is particularly suitable for robust estimates of camouflage efficacy. 相似文献
87.
This article examines the Ottoman military's escalatory response to violence and frames the Armenian insurrection of 1915 in the historical context of contemporary early twentieth-century counterinsurgency campaigns. A case study is presented, from a military historian's perspective, of counterinsurgency operations conducted by the Ottoman Army's 41st Infantry Division against Armenian insurgents on Musa Da? (Musa Dagh) in an operational area south of Iskenderun (Alexandretta). In this particular operational area, it appears that the modern label which most closely approximates what happened there is ethnic cleansing. Finally, the article concludes with an objective assessment of the effectiveness of the Ottoman Army's counterinsurgency operations. 相似文献
88.
Marc R. DeVore 《Small Wars & Insurgencies》2013,24(1):144-173
Following the emergence of a communist regime in South Yemen and the multiplication of subversive movements in the United Kingdom's Gulf protectorates, British policymakers genuinely feared the spread of communism throughout southern Arabia. Defeating the People's Front for the Liberation for the Occupied Arabian Gulf (PFLOAG) insurgency in Oman's Dhofar province was considered central to preventing such an outcome. In their pursuit of victory, British officers overthrew the sultan of Oman, escalated the war by conducting attacks in South Yemen, and, ultimately, appealed to Islam as a means of rallying support against communism. However, lessons learned in previous counterinsurgencies (Malaya, Kenya, and Borneo) proved of only limited value in Oman's physical and cultural environment. Unfortunately, none of these measures worked as anticipated. Only Iran's direct military intervention and the dramatic growth of Oman's financial resources after the 1973 oil crisis provided the resources to conduct large-scale offensive operations. Even so, victory was only achieved in 1975 because the rebellion's leaders unwisely attempted to oppose the Anglo–Omani offensives conventionally. 相似文献
89.
Maura R. Cremin 《Small Wars & Insurgencies》2013,24(6):912-936
AbstractThe 1919-1921 Anglo-Irish War represents one of the earliest instances of a successful insurgent movement in the twentieth century. By combining a fluid organizational structure with effective hit-and-run tactics and accurate intelligence, the Irish Republican Army was able to defeat militarily the security forces of Great Britain. Combined with a successful propaganda campaign, these tactics allowed the IRA to drive the British to the negotiating table, where its representatives secured greater autonomy than Ireland had known in centuries. The outcome of the Anglo-Irish War demonstrates the success which a well-organized guerrilla campaign can achieve, and the tactics used by the IRA must therefore be understood by any serious student of small warfare. 相似文献
90.
Charles R. Boehmer 《Defence and Peace Economics》2013,24(3):249-268
This paper extends the joint product model of military alliances to apply to the new strategic doctrine adopted by NATO in the 1990s. In particular, a choice must be made between protecting one's own territory and pooling forces for an alliancewide rapid reaction force. This new model accounts for a host of externalities and their implications for burden sharing, full financing, and allocative efficiency. The Pigouvian taxes that adjust for force thinning and attack deflection are shown to finance optimal border‐protecting forces under a variety of circumstances. Second‐best considerations arise owing to the pure publicness of rapid reaction forces. The ideal toll arrangement does not currently characterize NATO financing, nor is it likely to do so. 相似文献