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951.
Michael Holzhauser Sven O. Krumke Clemens Thielen 《Journal of Combinatorial Optimization》2017,33(4):1226-1256
Processing networks (cf. Koene in Minimal cost flow in processing networks: a primal approach, 1982) and manufacturing networks (cf. Fang and Qi in Optim Methods Softw 18:143–165, 2003) are well-studied extensions of traditional network flow problems that allow to model the decomposition or distillation of products in a manufacturing process. In these models, so called flow ratios \(\alpha _e \in [0,1]\) are assigned to all outgoing edges of special processing nodes. For each such special node, these flow ratios, which are required to sum up to one, determine the fraction of the total outgoing flow that flows through the respective edges. In this paper, we generalize processing networks to the case that these flow ratios only impose an upper bound on the respective fractions and, in particular, may sum up to more than one at each node. We show that a flow decomposition similar to the one for traditional network flows is possible and can be computed in strongly polynomial time. Moreover, we show that there exists a fully polynomial-time approximation scheme (FPTAS) for the maximum flow problem in these generalized processing networks if the underlying graph is acyclic and we provide two exact algorithms with strongly polynomial running-time for the problem on series–parallel graphs. Finally, we study the case of integral flows and show that the problem becomes \({\mathcal {NP}}\)-hard to solve and approximate in this case. 相似文献
952.
In a recent paper in this journal, Dagsvik derives the class of independent random utility representations that are “equivalent” to the independence-from-irrelevant-alternatives (IIA) assumption by Luce (Individual choice behavior: a theoretical analysis. Wiley, New York, 1959). In this short note, we clarify the relations between this paper by Dagsvik, and a paper in Lindberg’s 2012 thesis. 相似文献
953.
Jelani Kerr Anita Minh Arjumand Siddiqi Carles Muntaner Patricia O’Campo 《Journal of youth studies》2019,22(5):623-641
Labor force and school attachment may influence alcohol, tobacco, and marijuana use in the US and Canada. Differences in social welfare provision, which provide protections for individuals with insecure attachments to the labor force or education, may in turn impact the behavior and health of youth in these countries. Yet, there is little research to understand the health consequences for youth of being out of the labor force and school (OLFS). Data of 25–29 year old participants of the National Longitudinal Survey of Youth (year 2010) and the Canadian Community Health Survey (2009–2010) were used to examine differences in substance use by labor force and school attachment. Logistic regression suggests that OLFS in the US and Canada were less likely to report alcohol uptake and more likely to use tobacco compared to employed youth. Unemployment was differentially associated with substance use behaviors by country. Country of residence and subsequent exposure to social welfare policy does not appear to impact substance use behaviors among OLFS. However, associations of unemployment and gender by country indicates differences in substance use behavior. More research should seek to understand factors that influence alcohol, tobacco, and marijuana use among OLFS and unemployed youth. 相似文献
954.
Objectives: Data documenting the scope of sexual health clinical services offered as public health in Canada are unavailable. This article provides first insights into the scope of STI and clinical sexual health services available nationally. Methods: Data were gathered using an online survey of 113 Canadian public health units. Results: Almost half of the clinics were not providing expedited partner therapy, one third were not providing point of care testing for HIV and one third were not using syndromic management of sexually transmitted infections (STIs). Low rates of physician support were evident. Conclusion: Given the ever-higher rates of STIs, findings from this study identify important challenges to providing comprehensive services. 相似文献
955.
阶级分析的三种逻辑与中产阶级研究 总被引:2,自引:1,他引:1
本文着重探讨阶级分析的不同传统所强调的三类因果过程:首先是对个体生活有着显著影响的不平等的生活条件相关联的机制;其次是与各种社会封闭形式(forms of socialclosure)有关的机制,社会封闭使得某些个人或群体通过排斥他人而享有获取资源和机会的优势;第三是与个人或群体通过控制他人活动而受益的方式有关的机制。这三类机制可分别称作:基于个人属性和生活条件的阶级划分机制、基于机会阻隔(opportunity-hoarding)的阶级划分机制和基于支配、剥削关系的阶级划分机制。对于中产阶级的分析可以联系上述三种机制进行理解:中产阶级在不平等的生活条件分布中占据中间位置;他们受益于劳动力市场中的机会阻隔,特别是通过技能认证和资格审查制度得以实现;他们在支配和剥削他人劳动的同时自身又受到支配和剥削。 相似文献
956.
Unlocking the mask: a look at the process by which authentic leaders impact follower attitudes and behaviors 总被引:15,自引:0,他引:15
Bruce J. Avolio William L. Gardner Fred O. Walumbwa Fred Luthans Douglas R. May 《The Leadership Quarterly》2004,15(6):801-823
The conceptual and empirical links between authentic leadership and follower attitudes, behaviors, and performance outcomes have not been fully developed. Although we have a number of articles developing the theory of authentic leadership and testing propositions that will appear in a forthcoming special issue of The Leadership Quarterly (Vol. 16, Issue 3, 2005), the focus of this article is to provide some of the initial foundation work for the broader theoretical framework of how authentic leaders influence follower attitudes, behaviors, and performance. Here, we draw from positive organizational behavior, trust, hope, emotion, identification, and identity theories to describe the processes by which authentic leaders exert their influence on followers' attitudes and behaviors. Research propositions based on the proposed theoretical model and implications for future theory building and research are presented. 相似文献
957.
958.
The purpose of this study was to evaluate the effect of residual variability and carryover on average bioequivalence (ABE) studies performed under a 22 crossover design. ABE is usually assessed by means of the confidence interval inclusion principle. Here, the interval under consideration was the standard 'shortest' interval, which is the mainstream approach in practice. The evaluation was performed by means of a simulation study under different combinations of carryover and residual variability besides of formulation effect and sample size. The evaluation was made in terms of percentage of ABE declaration, coverage and interval precision. As is well known, high levels of variability distort the ABE procedures, particularly its type II error control (i.e. high variabilities make difficult to declare bioequivalence when it holds). The effect of carryover is modulated by variability and is especially disturbing for the type I error control. In the presence of carryover, the risk of erroneously declaring bioequivalence may become high, especially for low variabilities and large sample sizes. We end up with some hints concerning the controversy about pretesting for carryover before performing ABE analysis. 相似文献
959.
960.
Performance analysis of a multi-agent scheduling and control system under manufacturing disturbances
This paper is concerned with evaluating the performance of alternative multi-agent approaches to manufacturing planning and control. In order to separate the influence of ‘control algorithm’ from that of ‘control architecture’, a simple local control algorithm is chosen as a common starting point for developing the agent-based system. Two sets of experiments are then reported to evaluate how changes in individual agent characteristics can affect the control system's flexibility and adaptability against disturbances. These experiments show that the manufacturing and control system performance is not affected by architecture if the control algorithm remains fixed, however, altering the characteristics of the control system decision-makers influences both systems’ performance. 相似文献