Stochastic scheduling problems II-set strategies-

The paper introduces the finite class of set strategies for stochastic scheduling problems. It is shown that the knownstable classes of strategies such as ES and MES strategies are of this type, as arelist-scheduling strategies such as LEPT and SEPT and other, more complicatedpriority-type strategies. Roughly speaking, set strategies are characterized by the fact that the decision as to which jobs should be started at timet depends only on the knowledge of the two sets of jobs finished up to timet and being processed at timet. Contrary to list scheduling strategies, set strategies may involve deliberate idleness of machines, i.e. may not be greedy and can therefore not generally be induced by priority rules. It is demonstrated that set strategies have useful properties. They are e.g. ⁿ -almost everywhere continuous and therefore show satisfactorystability behaviour w.r.t. weak convergence of the joint distribution of job durations. Furthermore, the optimum w.r.t.all strategies is already attained on this class if job durations are independent and exponentially distributed and the performance measure fulfills a certainshift condition. This shift property is a quite natural concept and generalizes aspects of the notion ofadditivity in semi-Markov decision theory and stochastic dynamic optimization. Its complete analytical characterization is a major object of this paper. Typical additive cost criteria such as makespan and flowtime are of course covered, which yields simultaneously a first step towards generalization of optimality of LEPT and SEPT rules, as known for special cases. In fact, in view of the obtained optimality result, the question of when deliberate idleness of machines can be avoided, gains considerable interest, as it characterizes stochastic environments in whichpriority strategies are optimal. This provides a major link with current research on the analysis of networks of queues in the context of computer systems.The work of the first two authors was supported by the Minister für Wissenschaft und Forschung des Landes Nordrhein-Westfalen, while the work of the last author was supported by DAAD.     

Incentive equilibrium in an overlapping-generations environmental game

We consider two overlapping generations that want to coordinate their strategies of working, consuming and controlling pollution. Since the cooperative solution is not an equilibrium, and hence is not a self-enforcing contract, a mechanism is required to sustain it. We show how incentive strategies, and the resulting incentive equilibrium, could provide such a mechanism. We also derive the conditions that ensure the credibility of these strategies.     

Optimal Policies to Obtain the Most Join Results

Consider two finite or infinite populations, each member of which carries a positive integer valued label. Samples are drawn without replacement. A match is said to occur between two sampled members if they are from different populations and carry the same label. The object is to sample from the two sources in an order that maximizes the number of matches, uniformly across all steps. An optimal strategy is identified in the infinite case. In the finite case, while an optimal policy is shown to not always exist, we identify a policy which beats one that is commonly used. The work is motivated by a database problem in computer science. Many of the results are established through the probabilistic technique of coupling.     

Li-rich layered oxides: Structure,capacity and voltage fading mechanisms and solving strategies

Lithium rich layered oxides (LLOs) are attractive cathode materials for Li-ion batteries owing to their high capacity (>250 mA h g^–1) and suitable voltage (∼3.6 V). However, they suffer from serious voltage and capacity fading, which is focused in this review. First, an overview of crystal structure, band structure and electrochemical performances of LLOs is provided. After that, current understanding on oxygen loss, capacity fading and voltage fading is summarized. Finally, five strategies to mitigate capacity and voltage fading are reviewed. It is believed that these understandings can help solve the fading problems of LLOs.     

地位差异视角下知识分享策略对组织学习的影响研究

组织学习是提高企业竞争能力的重要途径,人际学习是组织学习的重要组成部分。组织成员间普遍存在的地位差异,会直接影响个体的知识分享策略,继而影响组织学习。然而,以往的组织学习模型通常忽略了个体的地位差异,默认假设每个组织成员的地位是相同的。鉴于此,本文在组织学习经典仿真模型的基础上,引入地位这一特征,综合探讨正向差异化(高地位成员更愿意分享知识)、负向差异化(低地位成员更愿意分享知识)、以及同质化(不同地位的成员有相同的知识分享意愿)这三种知识分享策略对组织学习的影响机理。研究结果表明,三种知识分享策略下,知识分享水平和地位认可度对组织学习的作用关系和作用大小存在显著差异。但总体来说,仅当组织成员的地位认可度较高且知识分享水平较低时,同质化策略才最有利于组织学习;其他情境下,负向差异化策略更有利于提高组织学习绩效。     

Two-sided approximations for unilateral variational inequalities by multi-grid methods

For the numerical solution of unilateral variational inequalities two iterative schemes are developed which provide approximations from below resp. from above. Both schemes are based on some kind of active set strategy and require the solution of an algebraic system of equations at each iteration step which is done by means of multigrid techniques. Convergence results are established and illustrated by some numerical results for the elastic-plastic torsion problem     

Strategic joining in M/M/1 retrial queues

The equilibrium and socially optimal balking strategies are investigated for unobservable and observable single-server classical retrial queues. There is no waiting space in front of the server. If an arriving customer finds the server idle, he occupies the server immediately and leaves the system after service. Otherwise, if the server is found busy, the customer decides whether or not to enter a retrial pool with infinite capacity and becomes a repeated customer, based on observation of the system and the reward–cost structure imposed on the system. Accordingly, two cases with respect to different levels of information are studied and the corresponding Nash equilibrium and social optimization balking strategies for all customers are derived. Finally, we compare the equilibrium and optimal behavior regarding these two information levels through numerical examples.     

Modeling and simulation of high-speed passenger train movements in the rail line

In this paper, we propose a new formula of the real-time minimum safety headway based on the relative velocity of consecutive trains and present a dynamic model of high-speed passenger train movements in the rail line based on the proposed formula of the minimum safety headway. Moreover, we provide the control strategies of the high-speed passenger train operations based on the proposed formula of the real-time minimum safety headway and the dynamic model of highspeed passenger train movements. The simulation results demonstrate that the proposed control strategies of the passenger train operations can greatly reduce the delay propagation in the high-speed rail line when a random delay occurs.     

Operational and design considerations for broad area graded barrier quantum well heterostructure lasers grown by metalorganic chemical vapor deposition for high power applications

Graded barrier quantum well heterostructure (GBQWH) broad area lasers have been shown to be capable of high power pulsed and cw operation. In this article, we consider several operational characteristics and design issues associated with broad area graded barrier quantum well heterostructure lasers grown by metalorganic chemical vapor deposition. In particular, the effect of junction heating on emission wavelength for cw device operation and the effects of various buffer layer structures on the material properties and device characteristics of GBQWH structures are addressed. Typical results for high power operation of uncoated broad area laser diodes are also outlined.