基于社会网络视角的突发灾害应急响应合作者关系网络分析——以“6·24”叠溪滑坡灾害为例

突发灾害应急管理实践表明,响应主体间的合作关系网络可靠性将影响应急响应的效率。本文以“6.24”新磨滑坡作为研究案例,采用文献分析、访谈、关系挖掘等研究方法构建灾害响应过程中主体间的合作者关系网络,重点从社会网络视角对该合作者关系的网络韧性进行量化分析,并对比随机生成的合作网络以及国外类似案例。研究发现,应急响应网络中的关键行动主体履行了救灾响应所要求的责任角色;在应急救援的效率方面,我国的应急救援体制具有制度优越性;指挥部等关键行动者会影响整个合作网络的效率和韧性。因此,在灾后应急救援时需进一步提升整体网络成员中协同救灾的水平,以在救援效率和效果上取得实效。     

应急响应的时效性评估问题研究

应对突发事件的关键在于时间上要快,效果上要好,综合考虑这两方面的评估被称为时效性评估。应急响应程序是由多个具有逻辑先后顺序的应对行动组成的,前面行动执行的效果会对后面的行动产生影响,不同行动的特点和评价指标是不一样的。根据行动的评价指标与其时效性的定性关系,通过构造函数定量表达的方法,给出了不同行动的时效性评估函数。并针对资金固定时单行动的时效性评估问题进行了理论研究,通过推导证得该行动不同质量的同一种类资源的配比存在着最优值,使得其时效性评估函数值达到最大。本研究对分析影响时效性的主要因素奠定了基础。     

考虑双方感知满意度的应急资源再配置方法

突发事件常诱发次生灾害,在外界大规模应急资源配送前,发挥区域互救优势,共享原生灾害点应急资源进行资源再配置是及时响应次生灾害的重要手段之一。本文尝试将灾民心理因素融入到应急资源的再配置问题中,基于前景理论提出了原生灾害点灾民的感知满意度模型,结合生存概率曲线对次生灾害点灾民感知满意度进行刻画,构建了考虑双方灾民感知满意度的多目标优化模型。此外,引入缩放系数和违反约束检查函数,改进多目标粒子群算法以加快算法初始化,进而提升模型求解效率。最后,本文通过算例验证了模型和算法的可行性和科学性,并与传统资源配置问题进行了对比,为具有连锁反应的突发事件应急管理提供决策支持。     

基于网格化管理视角下灾后应急物流决策模型与算法研究

灾害发生后,应急资源的需求预测与应急配送中心的合理选址是实现高效救援的关键。本文通过在网格化管理视角下的信息更新将应急救援过程划分为多个阶段,在开展救援的过程中实现救援信息收集和救援预测的同步开展,建立一种多阶段带时间约束的应急救援物资配送响应-时效性的选址模型。借助遗传算法(NSGA-II),实现了基于编码结构独立、路径相互关联基础上的多目标规划求解。本研究的决策模型及算法有着较好的搜索与寻优能力,对实际救援开展具有指导意义。     

风险应对视角下不确定需求定位-路径鲁棒优化研究

及时准确地配送应急救援物资是突发公共事件救援过程中的关键环节,综合考虑应急救援过程中出现的需求随机性,路网的连通能力下降和设施点失灵等情况,采用车辆与直升机联合运输方式进行配送,以应急系统中各物资需求点的救援时间满意度之和最大、系统总成本最小及物资到达需求点的救援时间之和最小为目标,对多式联运三级网络应急物流系统定位—路径优化问题进行研究,建立了多目标定位—路径模型,并改进了遗传算法。最后,以汶川地震应急救援相关数据为例,对模型和算法的有效性进行了数据仿真验证,通过实验结果的对比分析,证明了鲁棒优化方法在处理不确定需求和设施失灵风险方面的有效性,进而为抵御突发公共事件发生后出现的风险,为解决突发公共事件发生后救援物资的安全及时准确配送提供了有效的方法。     

多阶响应下军事物流配送中心可靠选址模型

为了提高战时物资配送的敏捷性和可靠性,结合军事物资配送的多阶响应过程,以部队用户对配送响应的时间约束为限制条件,以设施固定成本与期望配送成本之和为目标函数,并考虑设施未来失效的可能,建立了混合整数规划形式的军事物流配送中心可靠选址模型.结合模型的特点,采用基于时间约束的启发式算法将模型转化为可行子问题进行求解,使用仿真算例说明模型的优越性和算法的有效性.与不考虑设施失效的选址模型相比,考虑设施失效的选址方案在出现设施失效时,其应急配送成本平均增加量基本不超过设施固定成本的20％,平均最大增加量不超过25％;同一种失效情景下,考虑设施失效的选址方案的应急配送总成本也明显小于不考虑设施失效的选址方案的总成本.     

基于两阶段混合整数规划模型的洪涝灾害应急管理研究

本文以洪涝自然灾害为现实背景, 考虑多种应急物资、灾情的不确定性和应急救灾的多目标性, 集成优化灾前准备和灾后响应两阶段, 建立了一定最大救援时间下的两阶段多目标混合整数规划模型。模型的目标一是使得不同灾害情景下灾后响应阶段总物资不足惩罚和延误损失的期望最小, 目标二是使得灾前准备阶段应急物资存储点建造成本、物资存储成本及灾后响应阶段物资分配成本之和最小。该模型保证了应急救灾的及时有效以及物资的公平分配。本文设计了一种多目标遗传算法用于模型求解, 结合具体算例, 得到了模型在最大救援时间为4到9区间内任意数值下的pareto最优解, 很好地适应了决策者不同的决策需求, 并根据pareto应急方案的数目, 灾后响应阶段成本期望和两阶段总成本等模型的三个关键产出随最大救援时间的变化趋势, 得出最优的最大救援时间为5.7。     

基于改进NSGA-II算法的多级服务设施备用覆盖选址决策模型

为了应对跨区域突发事件过程中受灾点服务差异化需求的问题,建立了应急储备设施点的多级备用覆盖选址决策模型,即一个需求点由多个应急设施提供不同质量水平的服务,并考虑设施繁忙状态下由其他设施点提供服务的状况,使模型更加符合实际应用。首次通过设计分段的染色体编码方式改进NSGA-II算法提升运算效率以更好地解决多目标选址决策问题,将改进方法下得到的Pareto解分布与NSGA-II算法下的仿真结果进行对比分析,结合设施点的部署策略得到不同的空间布局方案。证明了模型的可行性及改进NSGA-II算法在解决设施点多目标选址决策问题时的有效性。     

考虑油膜动态过程的海上溢油应急物资调度优化

针对溢油应急响应中海上油膜所具有的动态特性,综合考虑需求点的时变物资需求、运输网络的不确定性以及物资调度决策与外部决策环境之间的相互作用关系之后,构建了效率目标与成本目标相结合的多目标海上溢油应急物资调度优化模型。根据模型的特点,提出了一种基于鲸鱼算法的求解方法。该算法利用非线性收敛因子克服了算法后期易陷入局部最优的不足,同时还引入小生境共享机制以确保解的多样性。最后,通过仿真案例对模型与算法的有效性与可行性进行了验证。结果表明,该方法可以为决策者提供高质量的决策支持。     

中转点变化的应急医疗物资联合运送干扰管理研究

应急响应中常常出现供应节点与需求节点距离太远、关键道路损毁等情境,此时直升机和车辆逐渐被联合使用以运送关键应急物资。由于原生及次生衍生灾害的发生发展,可能导致已有应急中转点不能使用,或者由于救援工作的开展,产生新的应急中转点等,这就可能导致事先已经制定的联合运送方案不能按照原计划进行。针对直升机和车辆联合运送中出现的中转点变化干扰事件,从物资到达时间、联合运送路线和使用运力三方面进行扰动度量,进而建立一个中转点变化的应急医疗物资联合运送干扰恢复模型,并通过改进基于客户的编码方法和提出基于简化策略的种群初始化方法等,设计了模型求解的遗传算法。数值实验验证了模型与算法的有效性,并通过与重优化方法对比,检验了干扰管理方法在处理中转点变化干扰事件中的优势。     

Unified Interactive Multiple Objective Programming: An Open Architecture For Accommodating New Procedures

It has previously been shown that nine of the most prominent procedures of interactive multiple objective programming can be considered as special cases of a common procedure called the unified algorithm. In this paper, we show how four additional procedures can be similarly included in the unified approach. Also, the paper presents a procedure-switching matrix that depicts the possibilities for switching from one procedure to another, one iteration to the next, in the unified algorithm if so directed by a user.     

Using restrictions to accept or reject solutions of radical equations

The standard technique for solving equations with radicals is to square both sides of the equation as many times as necessary to eliminate all radicals. Because the procedure violates logical equivalence, it results in extraneous solutions that do not satisfy the original equation, making it necessary to check all solutions against the original equation. We propose alternative solution procedures that are rigorous and simple to execute where the extraneous solutions can be identified without verification against the original equation. In this article, we review previous literature, establish and illustrate rigorous solution procedures for radical equations of depth 1 (i.e. equations where all radicals can be eliminated in one step), and deal with an ambiguity concerning the definition of real-valued solutions to radical equations. An application to defining the inverse function, resulting in a parametric radical equation, is also explained.     

On quantitative versions of theorems due to F.E. Browder and R. Wittmann

This paper is another case study in the program of logically analyzing proofs to extract new (typically effective) information (‘proof mining’). We extract explicit uniform rates of metastability (in the sense of T. Tao) from two ineffective proofs of a classical theorem of F.E. Browder on the convergence of approximants to fixed points of nonexpansive mappings as well as from a proof of a theorem of R. Wittmann which can be viewed as a nonlinear extension of the mean ergodic theorem. The first rate is extracted from Browder's original proof that is based on an application of weak sequential compactness (in addition to a projection argument). Wittmann's proof follows a similar line of reasoning and we adapt our analysis of Browder's proof to get a quantitative version of Wittmann's theorem as well. In both cases one also obtains totally elementary proofs (even for the strengthened quantitative forms) of these theorems that neither use weak compactness nor the existence of projections anymore. In this way, the present article also discusses general features of extracting effective information from proofs based on weak compactness. We then extract another rate of metastability (of similar nature) from an alternative proof of Browder's theorem essentially due to Halpern that already avoids any use of weak compactness. The paper is concluded by general remarks concerning the logical analysis of proofs based on weak compactness as well as a quantitative form of the so-called demiclosedness principle. In a subsequent paper these results will be utilized in a quantitative analysis of Baillon's nonlinear ergodic theorem.     

Alternative metrics to measure EMS system performance

In the development of strategy for the response to emergent incidents, emergency medical services (EMS) organizations must properly manage their resources while also adhering to response time mandates established by contractual agreements. Performance of an EMS system is typically measured by focusing on the response time of its first responders. However, given that some incidents require the response of multiple emergency vehicles, investigating only the initial response to incidents is inadequate. In this research, we propose two new metrics, in addition to the first response metric, to evaluate the performance of EMS operations: total response time and last responder response time. We develop three mixed integer programming formulations, each one focused on minimizing one of the three metrics, to model the assignment of emergency vehicles to incidents. We also propose a fourth model that combines the metrics via a weighted objective function. This model allows for the simultaneous consideration of the response metrics when evaluating the effectiveness of an emergency response dispatch policy. Experimental results, from comparisons of the models against a greedy dispatch policy, suggest the consideration of multiple response metrics leads to a more robust and effective dispatch policy. Finally, analysis using the models has potential to shape improved strategic and operational policies of EMS organizations. Journal of the Operational Research Society advance online publication, 29 June 2016; doi:10.1057/jors.2016.39     

随机需求应急物流多阶段定位-路径鲁棒优化研究

为提高应急物流系统的应急反应能力,论文针对需求随机变化的应急物流定位-路径问题,利用鲁棒优化的思想将灾区物资需求量表示为区间型数据,将应急救援过程划分为多个阶段,以总救援时间和系统总成本最小为目标,构建了多物资多运输车辆应急物流定位-路径优化模型,设计了改进的遗传算法对其进行求解。实例计算结果表明,该模型和算法可以有效地解决应急物流系统中需求随机变化的定位-路径问题,为政府机构应对重大突发事件提供科学的决策参考。     

基于FTA方法的COVID-19疫情应急防控决策研究

鉴于新型冠状病毒肺炎(COVID-19)的易感染性与聚集性等特点,基于COVID-19的传播机制,应用故障树分析(FTA)方法,研究了具有不同特征的疫情突发事件风险决策问题,包括疫情突发事件的动态演化过程、多种情景以及应急方案对突发事件的影响。通过分析COVID-19疫情突发事件的演化过程,构建故障树来描述导致突发事件演变的条件与因素之间的逻辑关系,给出了不同的可行应急方案。利用FTA预估出疫情突发事件发生的概率,计算出可行应急方案的整体排序值,获得最优应急方案。最后通过一个COVID-19确诊患者的案例分析,验证了所提出的方法的可行性和有效性。     

An integrated approach for risk response development in project planning

The risk response development phase is a major phase in the project risk management process. We present a model that integrates project work contents, risk events, and risk reduction actions and their effects into a comprehensive framework. The model allows the representation of the overlapping effects of multiple risk reduction actions and of the impacts of secondary risk events, and supports the evaluation of the total risk exposure of the project under various combinations of risk reduction actions. The model can be treated with optimisation techniques in order to generate the most cost-effective combination of risk reduction actions. In this work we describe the model, outline a solution procedure and illustrate its application with an example taken from the software industry.     

Designing WDM Optical Networks Using Branch-and-Price

In this paper, we present an exact solution procedure for the design of two-layer wavelength division multiplexing (WDM) optical networks with wavelength changers and bifurcated flows. This design problem closely resembles the traditional multicommodity flow problem, except that in the case of WDM optical networks, we are concerned with the routing of multiple commodities in two network layers. Consequently, the corresponding optimization models have to deal with two types of multicommodity variables defined for each of the network layers. The proposed procedure represents one of the first branch-and-price algorithms for a general WDM optical network setting with no assumptions on the number of logical links that can be established between nodes in the network. We apply our procedure in a computational study with four different network configurations. Our results show that for the three tested network configurations our branch-and-price algorithm provides solutions that are on average less than 5 % from optimality. We also provide a comparison of our branch-and-price algorithm with two simple variants of the upper bounding heuristic procedure HLDA that is commonly used for WDM optical network design.