A vacation scheduling algorithm for military flight crews: Maximizing satisfaction while maintaining military preparedness

This article develops a quantitative method of assigning leave to crewmembers in an operational military flying squadron. The objective of the assignment process is to maximize crew preferences. This objective is limited by manning constraints which limit the number of crews that can be on leave at the same time. The basis of the assignment process is a point system which allows each crew to bid for the periods they prefer. The periods are then assigned to the highest bidder. In this way, each crew is assured of an influence in the leave assignment process, and the results are entirely in the hands of the crews themselves. The method now used to assign leave was developed and refined during a three year period from 1981 to 1983. The 1983 method includes a two-phase partially open bidding system.In Phase I, crews signed up on a posted calendar for the periods they wanted, but they did not assign points to the periods. During this phase, crews could change their period request as they saw what other crews requested. This allows crews to sequence themselves to avoid conflicts. At the end of Phase I, the juggling process was closed, and crews could no longer change their period request. Crews were given a week between the close of Phase I and the start of Phase II to see how many other crews they were competing with. Then in Phase II, they submitted their points via closed bid.This system was very effective in both distributing the demand and preventing “gaming.” There was a strong disincentive from changing a period request at the last minute. If they did, the competition had a week to see whom they were competing with and could then bid accordingly. It was to everyone's advantage to avoid competition.Statistical analysis and positive feedback from crews and scheduling personnel have proven this method to be significantly superior to the former system.     

早高峰地铁站乘客上下车混行阶段影响分析

早高峰地铁站人流拥挤,地铁车门作为上下车人员的交汇界面,此过程中相互拥挤容易发生人员挤压、拉扯、踩踏事件,是安全管理面对的重要问题。实际观察我国乘客上下车一般可分为三个阶段：乘客下车阶段、乘客上下车混行阶段、乘客上车阶段。通过高密度人群的受力模型分析及上下车时间模型与实际观测的对比发现,地铁早高峰乘客上下车时,上下车混行阶段减慢乘客上下车效率并且是发生推挤、堵塞等事故的主要阶段。通过减少或消除乘客上下车混行阶段能提高乘客上下车效率并减少乘客上下车时的事故发生。同时提出可行的相关管理建议。     

Vertical Disintegration: A Dynamic Markovian Approach

In a model where a monopolistic downstream firm (assembler) negotiates simultaneously with each of its intermediate‐input suppliers the prices of the complementary components which enter its product, we analyze the process by which the assembler separates from its suppliers as a Markov Perfect equilibrium. Due to a negative strategic effect (the prices and profits of independent suppliers decrease when their number increases), the assembler’s marginal return from keeping an upstream subsidiary is lower than the market value of an independent supplier. Separation is immediate when the downstream firm’s initial number of upstream subsidiaries is below a critical level. It is progressive in the reverse case and eventually leads to a mixed strategy whereby the assembler keeps all the remaining subsidiaries with some probability, and sells all them off in one go with the complementary probability.     

The relative efficiency of public versus private municipal bus firms: An application of data envelopment analysis

This article has employed the data envelopment analysis method to evaluate the efficiency of the five bus firms in Taipei city. When vehicle kilometers (revenue or the measure combining vehicle kilometers, revenue and the number of traffic trips on routes) was used as the output measure, it concluded that the publicly owned Taipei Municipal Bus had increased (not increased) its technical efficiency after the government liberalized the urban bus market. This article also found that in both the one output (vehicle kilometers) and three outputs cases, Taipei Municipal Bus had, on an average, lower efficiency scores than the private firms, and that while each firm usually employed a linear production technology for several, consecutive years the private firms were more flexible in adopting different technologies.     

供应链电子采购的Stackelberg模型分析

利用Intemet进行采购是企业电子商务战略中最重要的部分。但是。目前关于电子采购的研究仍比较少。现有文献大多都是定性研究、实证研究或案例分析。定量研究非常少。文章从采购双方行为动机的角度出发,建立采购商为主方、供应商为从方的Stackelberg博彝模型;在模型的最优性分析基础上．讨论采购商的采购量与供应商的退款额之间的交互影响关系。     

Can Emotional Intelligence be developed?

This paper explores approaches to the development of Emotional Intelligence (EI) and to the critical question ‘can EI be developed?’ Technical data on the instruments used to measure EI, the Emotional Intelligence Questionnaire (EIQ) devised by Dulewicz and Higgs (2000c) and the EQ-i designed by Bar-On (1997), are reported. Findings from three studies involving managers, team leaders and the skippers and crews from a round-the-world yacht race are presented to explore whether Emotional Intelligence scores change after training and other experiences. A revised model to explain how the elements of Emotional Intelligence are related to each other is presented and tested, and possible explanations of why some elements are more amenable to development actions are proposed.     

Buyer–seller networks with demand shocks and intermediation

We present a model in which buyers and sellers use links to trade with each other. Each seller produces a good which can be one of two types. Buyers are ex ante identical but receive specification or valuation shocks after the links are formed. We show that efficient networks are stable and that severing a link in an efficient network results in a higher price for the buyer but a lower price for the seller. We also examine network intermediation when sellers (buyers) form links sequentially. When sellers form links sequentially, the first seller becomes an intermediary and shares links with other sellers; this makes all sellers better off. However, when buyers form links sequentially, buyers may or may not share links. If links are shared multiple intermediaries result.     

Queueing problems with arrivals in general stresm and phase type service

This paper deals with the steady state behaviour of a discrete time, single channel, first-come-first-served queueing problem wherein the service phases at two consecutive time-marks are correlated but the arrivals occur in General Stream. Probability Generating functions for the number of phases are obtained under two different models each with assumption that the service phases at two consecutive time marks are (i) correlated and (ii) uncorrelated. For each case the mean queue lengths when the number of phases demanded by an arriving unit is one, are derived. Some particular cases are discussed.     

Personnel scheduling with flexshift models

The concept of personnel scheduling when alternative work hours are permitted is presented in this article. The concept, called Flexshifts, schedules 6-, 8-, and 10-hour shifts against a 12- and 24-hour daily demand profile. Using the concept, required shifts can then be offered to the labor staff allowing each individual to select those shifts that best fit their personal plans. Alternatively, certain shifts can be guaranteed to key employees. Case studies reported in this paper indicate many advantages to allowing workers to opt for different start times, to select their days off and to create non-standard workweeks from predefined sets of 6-, 8-, and 10-hour days. Computerized timekeeping systems make this flexibility manageable. Personnel scheduling algorithms such as the one presented here make the planning of Flexshift easy.The formulation presented here utilizes linear programming. Tests of the L.P. Flexshift model on 42 data sets of 12-hour days showed an average savings in labor of 24.2% when compared to an L. P. model of the traditional 8-hour work shift. For a 24-hour work pattern, that formulation outperformed a published heuristic for 8-hour shifts by reducing average idle time from 13.9 to 5.4%.     

Eurozone

We expect the eurozone economy experienced a quarterly rise of around 10% in Q3 as activity benefited from favourable base effects after the collapse in Q2. However, the latest monthly data are confirming our fears that the recovery is tapering off quickly, as the number of Covid-19 infections continues to rise across the continent. PMIs declined for a second consecutive month in September amid a sharp fall in services, which highlights the impact that a second wave would have on the economy.     

Acting Intuition into Sense: How Film Crews Make Sense with Embodied Ways of Knowing

This study contributes to a holistic understanding of sensemaking by going beyond the mind–body dualism. To do so, we focus analytically on a phenomenon that operates at the nexus of mind and body: intuition. By observing four film crews, we unpack how people act their intuition into sense – that is, how they transform, through action, an initial sense (intuition) that is tacit, intimate, and complex into one that is publicly displayed, simpler, and ordered (i.e., a developed sense). Our model identifies two sensemaking trajectories, each of which involves several bodily actions (e.g., displaying feelings, working hands-on, speaking assertively). These actions enable intuition to express a facet of itself and acquire new properties. This study makes three important contributions. First, it develops the holistic-relational character of sensemaking by locating it in the relations among multiple loci (cognition, language, body, and materiality) rather than in each one disjunctively. Second, it theorizes embodied sensemaking as a transformative process entailing a rich repertoire of bodily actions. Third, it extends sensemaking research by attending to the physicality and materiality of language in embodied sensemaking.     

From London to Los Angeles: a comparison of local labour market processes in the US and UK film industries

Addressing the issue of the embeddedness of labour markets, this paper compares the processes of finding employment in the film industry within two local labour markets. Drawing on studies of freelance film crews in London (UK) and Los Angeles (US), the paper concludes that the importance of social networks in job mobility in both contexts is a consequence of common production structures. However, common labour market practice varies in each geographical space as industry processes and structures are mediated by local institutional contexts.     

基于知识转移视角的企业衍生过程分析

企业衍生是一种特殊的知识转移机制。本文从企业衍生在转移知识过程中的特殊性出发,把企业衍生的过程分为知识获取阶段、知识转移阶段、知识应用阶段三个阶段,建立基于知识转移视角的企业衍生过程的三阶段理论模型,并分别分析每个阶段的特殊的影响因素及其相互关系和作用方式。     

Local identifiability of the factor analysis and measurement error model parameter

Measurement error regression models are factor analysis models, the latent ‘correct’ regressors are the factors. There is however no common statistical method between the factor analysis and the regression model, because the covariance elements that are known identifying constituents of the former model are unknown in the latter. Instead, the idea that the data come from the same regression model, as with panel data, but can be grouped in two or more groups, each group having its own different regrressor generating process, is shown to supply credible restrictions. We generalize and compare relevant identifiability criteria and corresponding asymptotically efficient estimators that are recursive in the number of overidentifying restrictions.     

Peak-Load Pricing of a Bottleneck with Traffic Jam

This paper generalizes the model of bottleneck congestion such that formation and development of traffic jams is explicitly formulated. The model is applied to the peak-load problem for the morning rush hour: every morning, a fixed number of commuters travel across a roadway, and each of them chooses departure time to minimize commuting cost consisting of travel time cost, scheduling cost, and toll. Equilibrium and optimal patterns of departure are solved and optimal peak-load toll is derived. Incorporating traffic jams alters the earlier results in the literature. That is, road users may be better off from paying the optimal peak-load toll. Conditions under which such a result is obtained are identified by simulations.     

USING MODEL SELECTION ALGORITHMS TO OBTAIN RELIABLE COEFFICIENT ESTIMATES

This review surveys a number of common model selection algorithms (MSAs), discusses how they relate to each other and identifies factors that explain their relative performances. At the heart of MSA performance is the trade‐off between type I and type II errors. Some relevant variables will be mistakenly excluded, and some irrelevant variables will be retained by chance. A successful MSA will find the optimal trade‐off between the two types of errors for a given data environment. Whether a given MSA will be successful in a given environment depends on the relative costs of these two types of errors. We use Monte Carlo experimentation to illustrate these issues. We confirm that no MSA does best in all circumstances. Even the worst MSA in terms of overall performance – the strategy of including all candidate variables – sometimes performs best (viz., when all candidate variables are relevant). We also show how (1) the ratio of relevant to total candidate variables and (2) data‐generating process noise affect relative MSA performance. Finally, we discuss a number of issues complicating the task of MSAs in producing reliable coefficient estimates.     

Complete subset regressions

This paper proposes a new method for combining forecasts based on complete subset regressions. For a given set of potential predictor variables we combine forecasts from all possible linear regression models that keep the number of predictors fixed. We explore how the choice of model complexity, as measured by the number of included predictor variables, can be used to trade off the bias and variance of the forecast errors, generating a setup akin to the efficient frontier known from modern portfolio theory. In an application to predictability of stock returns, we find that combinations of subset regressions can produce more accurate forecasts than conventional approaches based on equal-weighted forecasts (which fail to account for the dimensionality of the underlying models), combinations of univariate forecasts, or forecasts generated by methods such as bagging, ridge regression or Bayesian Model Averaging.     

Semiparametric Bayesian inference in multiple equation models

This paper outlines an approach to Bayesian semiparametric regression in multiple equation models which can be used to carry out inference in seemingly unrelated regressions or simultaneous equations models with nonparametric components. The approach treats the points on each nonparametric regression line as unknown parameters and uses a prior on the degree of smoothness of each line to ensure valid posterior inference despite the fact that the number of parameters is greater than the number of observations. We develop an empirical Bayesian approach that allows us to estimate the prior smoothing hyperparameters from the data. An advantage of our semiparametric model is that it is written as a seemingly unrelated regressions model with independent normal–Wishart prior. Since this model is a common one, textbook results for posterior inference, model comparison, prediction and posterior computation are immediately available. We use this model in an application involving a two‐equation structural model drawn from the labour and returns to schooling literatures. Copyright © 2005 John Wiley & Sons, Ltd.     

The next hundred years of growth and convergence

World gross domestic product per capita is forecast to grow at 2.6% annually over the next 100 years. Convergence of less-developed countries toward output levels of the world frontier accounts for much of the forecast. Projecting recent growth in China and India accounts for much of the forecast convergence. The forecast differs from the earlier literature because the facts of convergence have changed in recent decades. A Markov-switching model is estimated for each country, allowing each country to switch on or off a path of convergence to the world output frontier. Bayesian estimates of the historical process and posterior forecasts are offered.