Energy modelling: A new challenge for management science

The Arab oil embargo in 1973 and the subsequent price rises and production restrictions have given birth to a distinct branch within Management Science: energy modelling. This paper gives a critical and selective review on energy modelling, an industry which though thriving in an era of general economic anxiety, is showing signs of arrogant immaturity. After giving a historical background, the paper classifies energy models into three groups: open loop demand or supply models; energy closed loop models; energy-economy closed loop models. For each group the problem area is analysed and some illustrative examples are described. In the last sections, an attempt is made to sum up the experience that has been gained with energy modelling: the basic deficiencies, the impact of this activity on policy formulation and its position within Management Science. It is concluded that energy models, though very poor forecasting devices, can be very useful to policy makers as tools for analysis; energy model developers must convince potential model users and for that purpose they can benefit immensely from the 35-year-long experience accumulated by their colleagues in Management Science.     

Large scale communication networks—Design and analysis

The paper discusses the problem of design and analysis of large scale communication systems. An iterative process, composed of a minimum cost network design algorithm and a network performance algorithm, is presented for the solution of these problems. Computational considerations, using these algorithms, are discussed.     

The use of strategic planning techniques in the United Kingdom

In this paper some of the techniques available for strategic planning are reviewed. Four techniques are presented, the experience curve, the growth-share matrix, the directional policy matrix and the PIMS program. The results of a survey into the use of these techniques in the United Kingdom are also presented.     

近四十年来韩国《史记》研究综述（1971—2010）

《史记》是中国史学中一部继往开来的不朽巨著,作者司马迁开创的以人物为中心的纪传体,在汉代以后一直是历代王朝正史所沿用的体制。司马迁修《史记》,不仅尊重历史事实,秉笔直书,而且还注意语言文字的锤炼,文句优美。他将叙事、抒情、说理的不同文体有机地综合起来,达到思想上、艺术上的高度统一,为后代文史创作提供了范例。《史记》不仅是中国纪传体史书的开创者,而且对后世的散文、小说、戏曲都产生了深远的影响。同时它也早已流传至国外,在汉文化圈国家中亦有不小的影响。其中,《史记》传入韩国,特别受到韩国知识界人士的关心和推崇,为韩国学术界所重视。到了1960年代中期,随着国家经济的发展,韩国整个社会的发展进入了一个历史的新时期,不仅国家面貌发生了根本性变化,学术文化事业也步入正轨,同时韩国学术界对中国学术文化的关心及研究也重新得到了高度重视。正是在这样的基础上,韩国学者对《史记》的翻译和研究有了较大的进展,在传播、普及和通俗化方面作出了积极的贡献。本文除简述《史记》在韩国的流传背景外,还分别论述自1971年至2010年近四十年来《史记》在当代韩国的翻译介绍与研究现状,并对其研究成果上存在的一些不足和空缺作一番客观的评价。     

Real-life closeness of social media contacts and depressive symptoms among university students

ABSTRACT

Objective: To examine the association between degree of real-life closeness of social media (SM) contacts and depressive symptoms. Participants: Students ages 18–30 (N = 1124) were recruited in August 2016. Methods: Participants completed an online survey assessing SM use and depression. We used multivariable logistic regression to assess associations between real-life closeness of SM contacts and depressive symptoms. Results: After controlling for covariates, each 10% increase in the proportion of SM friends with whom participants had no face-to-face relationship was associated with a 9% increase in odds of depressive symptoms (AOR = 1.09; 95% CI = 1.05–1.13). However, each 10% increase in the proportion of SM friends with whom participants had a close face-to-face relationship was associated with a 7% decrease in depressive symptoms (AOR = 0.93; 95% CI = 0.89–0.97). Conclusions: Having no in-person relationship with SM contacts is associated with increased depressive symptoms; however, having close in-person relationships with SM contacts is associated with decreased depressive symptoms.     

A reconceptualization of authentic leadership: Leader legitimation via follower-centered assessment of the moral dimension

We explore some challenges that face authentic leadership scholarship including problems related to how the construct is understood and measured. We present a model of authentic leadership that looks at it, not as a leadership style, but as an outcome of a legitimation process. Authentic leadership represents legitimated follower perceptions of a leader's authenticity which are activated by moral judgments. We explain how a follower-centered assessment of the moral component helps explain leadership dynamics in situations involving ethical relativism, thus alleviating concerns regarding the presumed moral component of the construct. The overlap between leaders' and followers' value systems leads to impressions of authenticity, even in cases in which there are no clear universal moral standards. An authentic person's behavior cannot be labeled as “leadership” unless it is embraced by a follower who grants moral legitimacy to the leader. We then discuss the implications of our study for scholars and practitioners.     

A methodological approach to strategic petroleum reserves

Energy constitutes a small fraction of the production inputs in the economy, yet the rigidity imposed by the short and medium term inability to substitute energy with other production factors in case of an energy shortage, requires the establishment of safeguard mechanisms to ensure sufficient energy supply during an emergency. These safeguards usually take the form of strategic energy reserves. A methodological approach is presented here, relating the level of strategic petroleum reserves, the decision variable, with the costs associated with their storage and the economic losses incurred by an energy shortage. This approach is based on the use of a decision tree, to portray emergency scenarios. Each scenario, a branch of the decision tree, can be evaluated in terms of a cost function which includes the inventory procurement and maintenance cost and the shortage cost inflicted by a petroleum shortfall.     

Tobacco,Marijuana, and Alcohol Use in University Students: A Cluster Analysis

Abstract

Objective: Segmentation of populations may facilitate development of targeted substance abuse prevention programs. The authors aimed to partition a national sample of university students according to profiles based on substance use. Participants: The authors used 2008–2009 data from the National College Health Assessment from the American College Health Association. The sample consisted of 111,245 individuals from 158 institutions. Methods: The sample was partitioned using cluster analysis according to current substance use behaviors. The association of cluster membership with individual and institutional characteristics was examined. Results: Cluster analysis yielded 6 distinct clusters. Three individual factors—gender, year in school, and fraternity/sorority membership—were the most strongly associated with cluster membership. Conclusions: In a large sample of university students, the authors were able to identify 6 distinct patterns of substance abuse. It may be valuable to target specific populations of college-aged substance users based on individual factors. However, comprehensive intervention will require a multifaceted approach.     

Route first—Cluster second methods for vehicle routing

In this paper we consider route first—cluster second methods for the vehicle routing problem. Extensions to the basic method both to improve its effectiveness and to enable it to cope with practical constraints are described. Computational results are given for the method applied to standard vehicle routing problems drawn from the literature.