Inventory System Subject to Disaster with General Interarrival Times

Abstract

We discuss a single commodity continuous review (s, S) inventory system in which commodities get damaged due to external disaster. Shortages are not permitted and lead time is assumed to be zero. The interarrival times of demands constitute a family of i.i.d. random variables with a common arbitrary distribution. The quantity demanded at a demand epoch is arbitrarily distributed which depends only on the time elapsed since the last demand epoch. Transient and steady state probabilities of the inventory levels are derived by identifying suitable semi-regenerative process. In the case when the demand is for unit item and the disaster affects only an exhibiting item, the steady state probability distribution is obtained as uniform. An optimization problem is discussed and numerical examples are provided.     

Emergency response to disaster-struck scale-free network with redundant systems

Disasters cause tremendous damage every year. In this paper, we have specifically studied emergency response to disaster-struck scale-free networks when some nodes in the network have redundant systems. If one node collapses, its redundant system will substitute it to work for a period of time. In the first part, according to the network structure, several redundant strategies have been formulated, and then our studies focused on their effectiveness by means of simulation. Results show that the strategy based on total degrees is the most effective one. However, many nodes still collapse in the end if redundant systems do not have sufficient capability, so emergency responses are necessary. Several emergent strategies controlling the distribution of external resources have been proposed in the second part. The effectiveness of those emergent strategies are then studied from three aspects, such as the effect of strategies on spreading processes, minimum sufficient quantities of external resources and determination of the most appropriate emergent strategy. In addition, the effects of redundant intensity on these aspects have been discussed as well.     

Analysis of the GI/Geo/1 Queue with Disasters

The occurrence of disasters to a queueing system causes all customers to be removed if any are present. Although there has been much research on continuous-time queues with disasters, the discrete-time Geo/Geo/1 queue with disasters has appeared in the literature only recently. We extend this Geo/Geo/1 queue to the GI/Geo/1 queue. We present the probability generating function of the stationary queue length and sojourn time for the GI/Geo/1 queue. In addition, we convert our results into the Geo/Geo/1 queue and the GI/M/1 queue.     

多光谱遥感在重大自然灾害评估中的应用与展望

重大自然灾害发乍后,及时、准确的灾情评估对决策部门制定科学和有效的救灾减灾方案具有关键性的作用.多光游遥感具有数据获取范围广、速度快等特点.应用在灾害评估中具有非常大的优势和潜力.在我国近年来的多次重大自然灾害评估中,多光谱遥感技术都发挥了重要的作用.该文首先以地震灾害、洪涝火害和十旱灾害为例,简要总结了多光谱遥感在重...     

Prepositioning supplies in preparation for disasters

In this paper, we examine the decision of where to preposition supplies in preparation for a disaster, such as a hurricane or terrorist attack, and how much to preposition at a location. If supplies are located closer to the disaster, it can allow for faster delivery of supplies after the disaster. As a result of being closer, though, the supplies may be in a risky location if the disaster occurs. Considering these risks, we derive equations for determining the optimal stocking quantity and the total expected costs associated with delivering to a demand point from a supply point. We provide a sensitivity analysis to show how different parameters impact stocking levels and costs. We show how our cost model can be used to select the single best supply point location from a discrete set of choices and how it can be embedded within existing location algorithms to choose multiple supply points. Our computational experiments involve a variety of relationships between distance and risk and show how these can impact location decisions and stocking levels.     

四川泸定磨西台地第四纪冰水台地边坡地质灾害易发性研究

河流冲刷对第四纪软弱地层岸坡的地质灾害起到控制性作用。本文以磨西台地冰水堆积物岸坡为例,充分考虑河流与岸坡地质灾害之间的内在联系,基于对实测地质灾害的分析结果,采用Logistic监督分类方法,评价各环境因子（尤其是河流冲蚀特性因子）在河流岸坡稳定性评价中的作用,进而采用高相关的环境因子进行地质灾害易发性预测。研究表明,河流弯曲度、河流流量、岸坡坡度、河床宽度、岸坡宽度与地质灾害的发育相关性强,采用这些参数和Logistic模型预测的地质灾害易发性能很好的反映现状和未来地质灾害的发育特点,进而提出了磨西台地岸坡地质灾害防治的初步建议。     

Hospital capacity,capability, and emergency preparedness

Disasters often result in shifts in hospital capacity utilization. Emergency preparedness plans must recognize capacity at the service-line level. This information can provide an additional level of detail to better design response activities and develop cost-effective disaster response plans. We model a possible preparedness plan for Florida hospitals in the case of a major disaster. We model a hurricane event because, in addition to its similarity to other disasters, it provides enough warning for substantive preparation activities. Following Johansen, we measure capacity in a frontier setting using data envelopment analysis. We also use a criterion of economic capability to ensure that a Pareto Optimal situation can be maintained. Information on hospital capacity, patient characteristics of inpatient discharges, and financial performance was merged to perform this study. Our findings suggest there is not enough excess capacity for some specialized services in Florida. However, possible evacuation policies can still be derived from our findings satisfying medical and economic capabilities.     

露天矿边坡动态整治方法及其应用——以福建潘洛铁矿滑坡整治为例

露天矿边坡属于人工边坡,它的形成不仅时间长,而且一直处于动态过程中。露天矿滑坡在一定范围内是允许的,滑坡治理的目的是保证矿山在开采期限内安全采出设计境界内的矿石。基于这些特征,在文中提出了适合露天矿滑坡治理的新方法-动态治理法及其可行性,并以潘洛铁矿露天矿滑坡灾害治理为例,对该方法的应用进行了论述。可为露天矿滑坡治理所借鉴。     

Aggregate-level demand management in evacuation planning

Without successful large-scale regional evacuations, threats such as hurricanes and wild-fires can cause a large loss of life. In this context, automobiles are oftentimes an essential transportation mode for evacuations, but the ensuing traffic typically overwhelms the roadway capacity and causes congestion on a massive scale. Congestion leads to many problems including longer, costlier, and more stressful evacuations, lower compliance rates, and increased risk to the population. Supply-based strategies have traditionally been used in evacuation planning, but they have been proven to be insufficient to reduce congestion to acceptable levels. In this paper, we study the demand-based strategies of aggregate-level staging and routing to structure the evacuation demand, both with and without congestion. We provide a novel modeling framework that offers strategic flexibility and utilizes a lexicographic objective function that represents a hierarchy of relevant evacuation-based goals. We also provide insights into the nature and effect of network bottlenecks. We compare our model with and without congestion in relation to tractability, normative optimality, and robustness under demand uncertainty. We also show the effectiveness of using demand-based strategies as opposed to using the status quo that involves a non-staged or simultaneous evacuation process. Effective solution procedures are developed and tested using hypothetical problem instances as well as using a larger study based on a portion of coastal Virginia, USA.     

A multi-agent optimization formulation of earthquake disaster prevention and management

Natural earthquake disasters are unprecedented incidents which take many lives as a consequence and cause major damages to lifeline infrastructures. Various agencies in a country are responsible for reducing such adverse impacts within specific budgets. These responsibilities range from before to after the incident, targeting one of the main phases of disaster management (mitigation, preparedness, and response). Use of OR in disaster management and coordination of its phases has been mostly ignored and highly recommended in former reviews. This paper presents a formulation to coordinate three main agencies and proposes a heuristic approach to solve the different introduced sub-problems. The results show an improvement of 7.5–24% when the agencies are coordinated.