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排序方式: 共有1355条查询结果,搜索用时 15 毫秒
1.
迄今,为解决多属性偏好关联决策属性集容量判断指数复杂性难题所提出的λ模糊测度模式与k-可加模糊测度模式,以及建构在它们之上的属性集容量确定的推算模型,尚存在着适用性差的技术不足。为此,以平衡容量判断的可操作性和容量推算的准确性为视角,提出了一种新容量测度模式,即关于容量判断与推算的夹挤式测度模式,并在此基础上通过引入决策者较易判断给出的容量序信息构建了相应的容量推算模型。基于数值模拟的对比分析表明:新模式不仅在应用可行性上高于k-可加模糊测度模式,而且从容量推算的准确性上看也明显优于λ模糊测度模式和k-可加模糊测度模式,因而对实际决策具有更强的适用性。  相似文献   
2.
Emergency material allocation is an important part of postdisaster emergency logistics that is significant for improving rescue effectiveness and reducing disaster losses. However, the traditional single‐period allocation model often causes local surpluses or shortages and high cost, and prevents the system from achieving an equitable or optimal multiperiod allocation. To achieve equitable allocation of emergency materials in the case of serious shortages relative to the demand by victims, this article introduces a multiperiod model for allocation of emergency materials to multiple affected locations (using an exponential utility function to reflect the disutility loss due to material shortfalls), and illustrates the relationship between equity of allocations and the cost of emergency response. Finally, numerical examples are presented to demonstrate both the feasibility and the usefulness of the proposed model for achieving multiperiod equitable allocation of emergency material among multiple disaster locations. The results indicate that the introduction of a nonlinear utility function to reflect the disutility of large shortfalls can make the material allocation fairer, and minimize large losses due to shortfalls. We found that achieving equity has a significant but not unreasonable impact on emergency costs. We also illustrate that using differing utility functions for different types of materials adds an important dimension of flexibility.  相似文献   
3.
一稿多投是学术界由来已久且难以医治的顽症。究其原因,主要是科研压力之下作者的投机心态、作者投稿经验的匮乏、稿件时效性的压力以及网上投稿的便捷与低成本等因素使然。一稿多投会造成编方人力资源的浪费,容易引发一稿多发,挤占宝贵的版面资源,引起版权纠纷,破坏学术诚信,扰乱科研秩序。要从加强制度建设、加大惩罚力度、利用高科技进行防范、健全监督机制、加强学术道德教育、提高编辑效率等方面,把"他律"与"自律"结合起来,惩防并举,标本兼治,多管齐下,齐抓共管,从根本上规范科研活动,根治一稿多投顽症。  相似文献   
4.
以社会行动者理论与多重制度逻辑框架为基础,从中央政府与地方政府两个行动者的多重逻辑出发,在央地互动视阈下对中国建设用地一级配置管理的政策演化与制度逻辑进行了解析。研究发现,在建设用地一级配置管理的制度变迁中,央地双方在多重逻辑的相互作用下,针对不同的土地利用计划指标类型,实质设立了差别化的行动准则:在中央权威有效性逻辑与地方代理自利性和局部自主性多重考量的相互回应下,对于新增建设用地计划指标,央地采取了掌控与突破的相斥性准则;在中央强公共性和有效性逻辑重叠与地方局部自主性逻辑的相互交织下,对于非新增建设用地计划指标,央地则采取了放权与执行的相容性准则。在这种差别化的行动准则下,央地双方展开了持续性互动,最终形成了新增建设用地指标愈发收紧的“计划管控”、非新增建设用地计划指标愈发灵活的“市场调剂”的“双轨化”变迁路径。由此可见,在央地政府这种差别化的行动准则下,中国未来的建设用地配置改革,不能只寄期望于诸如简单引入市场机制等治理结构层面的改变,还需要从深层次把握中央集权体制下央地政府的多重逻辑、管理诉求与互动策略,由此才能设计能够引导央地激励相容、优势互补的制度改进机制。  相似文献   
5.
In studies with recurrent event endpoints, misspecified assumptions of event rates or dispersion can lead to underpowered trials or overexposure of patients. Specification of overdispersion is often a particular problem as it is usually not reported in clinical trial publications. Changing event rates over the years have been described for some diseases, adding to the uncertainty in planning. To mitigate the risks of inadequate sample sizes, internal pilot study designs have been proposed with a preference for blinded sample size reestimation procedures, as they generally do not affect the type I error rate and maintain trial integrity. Blinded sample size reestimation procedures are available for trials with recurrent events as endpoints. However, the variance in the reestimated sample size can be considerable in particular with early sample size reviews. Motivated by a randomized controlled trial in paediatric multiple sclerosis, a rare neurological condition in children, we apply the concept of blinded continuous monitoring of information, which is known to reduce the variance in the resulting sample size. Assuming negative binomial distributions for the counts of recurrent relapses, we derive information criteria and propose blinded continuous monitoring procedures. The operating characteristics of these are assessed in Monte Carlo trial simulations demonstrating favourable properties with regard to type I error rate, power, and stopping time, ie, sample size.  相似文献   
6.
《Risk analysis》2018,38(6):1183-1201
In assessing environmental health risks, the risk characterization step synthesizes information gathered in evaluating exposures to stressors together with dose–response relationships, characteristics of the exposed population, and external environmental conditions. This article summarizes key steps of a cumulative risk assessment (CRA) followed by a discussion of considerations for characterizing cumulative risks. Cumulative risk characterizations differ considerably from single chemical‐ or single source‐based risk characterization. CRAs typically focus on a specific population instead of a pollutant or pollutant source and should include an evaluation of all relevant sources contributing to the exposures in the population and other factors that influence dose–response relationships. Second, CRAs may include influential environmental and population‐specific conditions, involving multiple chemical and nonchemical stressors. Third, a CRA could examine multiple health effects, reflecting joint toxicity and the potential for toxicological interactions. Fourth, the complexities often necessitate simplifying methods, including judgment‐based and semi‐quantitative indices that collapse disparate data into numerical scores. Fifth, because of the higher dimensionality and potentially large number of interactions, information needed to quantify risk is typically incomplete, necessitating an uncertainty analysis. Three approaches that could be used for characterizing risks in a CRA are presented: the multiroute hazard index, stressor grouping by exposure and toxicity, and indices for screening multiple factors and conditions. Other key roles of the risk characterization in CRAs are also described, mainly the translational aspect of including a characterization summary for lay readers (in addition to the technical analysis), and placing the results in the context of the likely risk‐based decisions.  相似文献   
7.
8.
系统总结了在伸展构造背景下,导致反映构造特征的地层倾角模式复杂化的多种因素。沉积相的不同、岩性变化、井眼状况和测井作业时间等多种因素都可能使地层倾角资料复杂化。进一步指出在拉张盆地中,进行倾角资料的构造解释,必须了解其构造样式的多样性和复杂性,解释存在的多解性。重点解剖了铲式断层在横剖面情况下,对于不同构造位置下的倾角模式。详细分析了一个倾角模式对应多种构造样式的倾角构造解释实例。倾角资料的构造解释应是综合解释,既要综合井筒的相关地质资料,又要综合测井与地质知识,还必须考虑综合地震资料。  相似文献   
9.
In view of the fact that culture‐inclusive psychology has been eluded or relatively ignored by mainstream psychology, the movement of indigenous psychology is destined to develop a new model of man that incorporates both causal psychology and intentional psychology as suggested by Vygotsky (1927). Following the principle of cultural psychology: “one mind, many mentalities” (Shweder et al., 1998), the Mandala Model of Self (Hwang, 2011a,b) and Face and Favor Model (Hwang, 1987, 2012) were constructed to represent the universal mechanisms of self and social interaction that can be applied to any culture; both models can be used as conceptual frameworks for analyzing mentalities of people in any given culture. Taking research works from Foundations of Chinese Psychology: Confucian Social Relation as exemplars (Hwang, 2012), this article illustrates how to construct culture‐inclusive theories of Confucianism by multiple philosophical paradigms. The mechanism of culture‐inclusive theory can be applied to explain qualitative research findings on lifeworld events of people in a particular society. It can also be utilized to predict results of quantitative research conducted to verify theoretical propositions in the scientific microworld by empirical methods.  相似文献   
10.
陶杰  高岩 《管理科学》2021,24(3):32-44
非线性优化模型中经常出现多重Lagrange乘子现象,导致决策者错误地计算资源的影子价格.本文针对该问题指出最小欧几里得范数的Lagrange乘子是影子价格.同时,还提出了一个无约束优化模型用以求解最小欧几里得范数 Lagrange乘子,该无约束优化模型可以通过经典的非光滑优化算法求解.最后,本文提出一个基于次梯度的算法求解影子价格,该算法是次线性收敛的,且计算时间与约束条件的个数及自变量的个数线性相关.  相似文献   
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