The falling tide algorithm: A new multi-objective approach for complex workforce scheduling

We present a hybrid approach of goal programming and meta-heuristic search to find compromise solutions for a difficult employee scheduling problem, i.e. nurse rostering with many hard and soft constraints. By employing a goal programming model with different parameter settings in its objective function, we can easily obtain a coarse solution where only the system constraints (i.e. hard constraints) are satisfied and an ideal objective-value vector where each single goal (i.e. each soft constraint) reaches its optimal value. The coarse solution is generally unusable in practise, but it can act as an initial point for the subsequent meta-heuristic search to speed up the convergence. Also, the ideal objective-value vector is, of course, usually unachievable, but it can help a multi-criteria search method (i.e. compromise programming) to evaluate the fitness of obtained solutions more efficiently. By incorporating three distance metrics with changing weight vectors, we propose a new time-predefined meta-heuristic approach, which we call the falling tide algorithm, and apply it under a multi-objective framework to find various compromise solutions. By this approach, not only can we achieve a trade off between the computational time and the solution quality, but also we can achieve a trade off between the conflicting objectives to enable better decision-making.     

A systematic and critical review of research on respect in leadership

Respect is an important psychological and interpersonal phenomenon that has been included in various theoretical and empirical approaches to leadership for nearly 70 years. In this systematic and critical review article, we provide a comprehensive summary and critique of theories, definitions, measures, and empirical studies of respect in leadership. We first provide an overview of the historical and theoretical background, including the most common theories, definitions, and measures that inform empirical studies of respect in leadership. Second, we present a systematic literature review of empirical studies on respect in leadership, including a critical evaluation of research designs and statistical analyses that support claims of the validity of various conceptualizations of respect that pertain to the study of leadership. Finally, we offer a new working definition of respect in leadership, and an accompanying conceptual framework which informs a number of recommendations for future theory development, empirical research, and leadership practice.     

A critical review of end-user information system satisfaction research and a new research framework

This paper presents a critical review of research in end-user information system satisfaction (EUISS). An extensive literature search is conducted from which over 50 EUISS related papers are identified. It is found that the past research is dominated by the expectation disconfirmation approach. To provide more insights into the psychological processing of the information system performance construct and its impact upon EUISS, we propose an integrated conceptual model based on the equity and needs theories. The implications of the proposed model for EUISS are discussed, and suggestions are made for testing the model.     

Putting consumer behaviour in its place: the Behavioural Perspective Model research programme

Consumer research remains overwhelmingly cognitive in orientation, partly because its apparent underlying philosophical stance usually goes unremarked and unchallenged. In so far as scientific progress relies on the interaction of competing theories, consumer research is impoverished by too great a reliance on a single approach to theory. This paper proposes an alternative to the prevailing 'intentional stance' on which consumer research predominantly rests; the 'contextual stance' eschews the intentionality of the cognitive explanations of consumer choice, substituting for it an account of behaviour determined by its environmental consequences. As a prelude to the interactive debate that these competing stances will hopefully engender, the paper demonstrates that the contextual stance is a viable strategy for consumer research. The contextual strategy leads to an alternative model of consumer choice to those based on social cognitive psychology. It is argued that this model of consumer choice in behavioural perspective provides a thoroughgoing conceptual reinterpretation of consumer behaviour and marketing management as currently envisaged.     

Multi-agent scheduling on a single machine with a fixed number of competing agents to minimize the weighted sum of number of tardy jobs and makespans

We study the multi-agent scheduling on a single machine with a fixed number of competing agents, in which, the objective function of each agent is either the number of tardy jobs or the makespan, and the goal of the problem is to minimize the weighted sum of agents’ objective functions. In the literature, the computational complexity of this problem was posed as open. By using enumerating, dynamic programming, and schedule-configuration, we show in this paper that the problem is solvable in polynomial time.     

A Diagnostic Tree for Improving Production Line Performance

Improving performance of production systems is a critical but often unstructured activity. To help managers convert ad hoc or trial & error improvement efforts into efficient and systematic reviews, we develop a diagnostic tree which decomposes a performance improvement objective into successively more concrete sub‐objectives and finally into potential improvement strategies. Based on principles from the Operations Management literature, this tree is structured to enable a non‐specialist to better understand the links between corrective actions and performance. It also provides an important foundation for a principles‐based knowledge management system that couples the decision tree with a search engine for locating relevant documents within an intranet.     

MULTIPERIOD SEARCH MODELS FOR AN UNKNOWN NUMBER OF VALUABLE OBJECTS

In this paper we examine multiperiod search models for cases in which the number of valuable objects is unknown. The objective is to maximize the expected total returns during the planning horizon, subject to an effort constraint. Using a Bayesian approach, we examine the model for three different priors for the number of valuable objects, and we show that the different priors (binomial, Poisson and negative binomial) lead to such conceptually different results as adaptive and nonadaptive optimal policies. The models can be applied to many areas including mineral explorations, marketing promotion activities and intelligence information.     

Uncovering the factors behind new ventures’ international performance: Capabilities,alertness and technological turbulence

This research is based on the perception that the explanation of International New Ventures' (INVs) performance demands a process view, going deeper than the standard approach, in empirical papers, of testing a direct relationship between company-level antecedents and performance. A three-tier model was developed to investigate the process leading to INVs international performance, emphasizing the role of entrepreneurial alertness. Based on the dynamic capabilities framework, entrepreneurial alertness was envisaged as the mediating element between firms' capabilities and their international performance. Empirical research confirmed the hypothesized model. Firms' capabilities (entrepreneurial orientation, foreign market knowledge, and absorptive capacity) significantly influence the level of entrepreneurial alertness, which impacts on the levels of self-reported satisfaction with the company's international performance. The paper makes four contributions to International Entrepreneurship literature. First, it highlights the key role played by entrepreneurial alertness in explaining INVs' international performance. This is convergent with the dynamic capabilities view on firms' ability to sense and seize specific international business opportunities. Second, this study considers entrepreneurial alertness as a capability that is not limited to the entrepreneur, but it is an organizational capability. Third, it shows that entrepreneurial alertness does not exist in the vacuum, is based on a set of base capabilities, namely entrepreneurial orientation, foreign market knowledge, and absorptive capacity, that simultaneously leverage the INVs to sense possible opportunities and constrain the focus of opportunities to international markets, as a key element to foster INVs' higher performance. Fourth, it underlines the role of technological turbulence as a moderator of the relationship between entrepreneurial alertness and INVs' international performance.     

Representation,Propagation, and Decision Issues in Risk Analysis Under Incomplete Probabilistic Information

This article tries to clarify the potential role to be played by uncertainty theories such as imprecise probabilities, random sets, and possibility theory in the risk analysis process. Instead of opposing an objective bounding analysis, where only statistically founded probability distributions are taken into account, to the full‐fledged probabilistic approach, exploiting expert subjective judgment, we advocate the idea that both analyses are useful and should be articulated with one another. Moreover, the idea that risk analysis under incomplete information is purely objective is misconceived. The use of uncertainty theories cannot be reduced to a choice between probability distributions and intervals. Indeed, they offer representation tools that are more expressive than each of the latter approaches and can capture expert judgments while being faithful to their limited precision. Consequences of this thesis are examined for uncertainty elicitation, propagation, and at the decision‐making step.     

A 14-h night-shift in the control room of a fire brigade

Abstract

All 29 operators in the control room of a fire brigade performed test sessions during work and leisure time at 2-h intervals on a day with a 14-h night-shift, a day off and a day with a 10-h morning shift. The test sessions consisted of a visual search choice reaction time test and two Sternberg memory search tests (1 or 5 letters had to be memorized). Furthermore, the operators recorded their oral temperature and their subjective alertness before each test session. The subject also kept a diary of work and sleep times for 14 days. The circadian rhythm of body temperature was hardly changed by a single night-shift. Parallel to the body temperature, the subjective alertness fell significantly during the night-shift reaching a minimum value at 06:00 h. The mean reaction times increased non-significantly at the end of the night-shift and the results of the two Sternberg memory search tests showed no significant trends. The sleep of the operators after the night-shift was on average reduced to 5 hs 34 min. The results of subjective rating of alertness and reaction time test are interpreted as effects of the combined influences of circadian rhythmicity, sleep loss and time on professional task. Most results support the conclusion that a 14-h night-shift without extensive breaks is not acceptable.     

Determining Order Quantity and Selling Price by Geometric Programming: Optimal Solution,Bounds, and Sensitivity*

This paper presents a geometric programming (GP) approach to finding a profit-maximizing selling price and order quantity for a retailer. Demand is treated as a nonlinear function of price with a constant elasticity. The proposed GP approach finds optimal solutions for both no-quantity discounts and continuous quantity discounts cases. This approach is superior to the traditional approaches of solving a system of nonlinear equations. Since the profit function is not concave, the traditional approaches may require an exhaustive search, especially for the continuous discounts schedule case. By applying readily available theories in GP, we easily can find global optimal solutions for both cases. More importantly, the GP approach provides lower and upper bounds on the optimal profit level and sensitivity results which are unavailable from the traditional approaches. These bounding and sensitivity results are further utilized to provide additional important managerial implications on pricing and lot-sizing policies.     

Interactive fuzzy goal programming for multi-objective transportation problems

This paper presents an interactive fuzzy goal programming approach to determine the preferred compromise solution for the multi-objective transportation problem. The proposed approach considers the imprecise nature of the input data by implementing the minimum operator and also assumes that each objective function has a fuzzy goal. The approach focuses on minimizing the worst upper bound to obtain an efficient solution which is close to the best lower bound of each objective function. The solution procedure controls the search direction via updating both the membership values and the aspiration levels. An important characteristic of the approach is that the decision maker's role is concentrated only in evaluating the efficient solution to limit the influences of his/her incomplete knowledge about the problem domain. In addition, the proposed approach can be applied to solve other multi-objective decision making problems. The performance of this solution approach is evaluated by comparing its results with that of the two existing methods in the literature.     

The flexible blocking job shop with transfer and set-up times

The Flexible Blocking Job Shop (FBJS) considered here is a job shop scheduling problem characterized by the availability of alternative machines for each operation and the absence of buffers. The latter implies that a job, after completing an operation, has to remain on the machine until its next operation starts. Additional features are sequence-dependent transfer and set-up times, the first for passing a job from a machine to the next, the second for change-over on a machine from an operation to the next. The objective is to assign machines and schedule the operations in order to minimize the makespan. We give a problem formulation in a disjunctive graph and develop a heuristic local search approach. A feasible neighborhood is constructed, where typically a critical operation is moved (keeping or changing its machine) together with some other operations whose moves are “implied”. For this purpose, we develop the theoretical framework of job insertion with local flexibility, based on earlier work of Gröflin and Klinkert on insertion. A tabu search that consistently generates feasible neighbor solutions is then proposed and tested on a larger test set. Numerical results support the validity of our approach and establish first benchmarks for the FBJS.     

A 14-h night-shift in the control room of a fire brigade

All 29 operators in the control room of a fire brigade performed test sessions during work and leisure time at 2-h intervals on a day with a 14-h night-shift, a day off and a day with a 10-h morning shift. The test sessions consisted of a visual search choice reaction time test and two Sternberg memory search tests (1 or 5 letters had to be memorized). Furthermore, the operators recorded their oral temperature and their subjective alertness before each test session. The subject also kept a diary of work and sleep times for 14 days. The circadian rhythm of body temperature was hardly changed by a single night-shift. Parallel to the body temperature, the subjective alertness fell significantly during the night-shift reaching a minimum value at 06:00 h. The mean reaction times increased non-significantly at the end of the night-shift and the results of the two Sternberg memory search tests showed no significant trends. The sleep of the operators after the night-shift was on average reduced to 5 hs 34 min. The results of subjective rating of alertness and reaction time test are interpreted as effects of the combined influences of circadian rhythmicity, sleep loss and time on professional task. Most results support the conclusion that a 14-h night-shift without extensive breaks is not acceptable.     

The selective minimum latency problem under travel time variability: An application to post-disaster assessment operations

In this paper, we consider a new selective routing problem, where a subset of customers should be serviced by a limited fleet of vehicles with the aim of minimizing the total latency. A service level constraint is added to guarantee that a minimum system performance is achieved. Assuming that the travel times are uncertain, we address the problem through a mean-risk approach. The inclusion of risk in the objective function makes the problem computationally challenging. To solve it, we propose an efficient heuristic, relying on a variable neighbourhood search mechanism, able to strike the balance between service level and latency. A detailed discussion of the model, which includes simulation tests and a sensitivity analysis, is carried out to illustrate the applicability of our approach in a post-disaster scenario, taking as a case study the Haiti earthquake in 2010. Additional computational experiments show that the proposed heuristic is effective for this difficult problem and often matches optimal solutions for small and medium-scale benchmark instances.     

Heuristic Estimation of the Efficient Frontier for a Bi-Criteria Scheduling Problem

We examine a single-machine scheduling problem where the objective is to minimize the mean and the variance of the job completion times simultaneously. We seek to identify the efficient frontier which is obtained by parametrically solving a weighted combination of the two criteria. The identification of the true efficient frontier for this problem is notoriously difficult. To estimate the frontier, we propose a heuristic procedure which is quite general and can be applied to other bi-criteria problems as well. It involves repeated applications of a relatively new technique called beam search in an adaptive manner. To evaluate the proposed procedure, we introduce two measures of performance and conduct a computational study. The results of the study indicate that the procedure is highly effective.     

A 14-h night-shift in the control room of a fire brigade

All 29 operators in the control room of a fire brigade performed test sessions during work and leisure time at 2-h intervals on a day with a 14-h night-shift, a day off and a day with a 10-h morning shift. The test sessions consisted of a visual search choice reaction time test and two Sternberg memory search tests (1 or 5 letters had to be memorized). Furthermore, the operators recorded their oral temperature and their subjective alertness before each test session. The subject also kept a diary of work and sleep times for 14 days. The circadian rhythm of body temperature was hardly changed by a single night-shift. Parallel to the body temperature, the subjective alertness fell significantly during the night-shift reaching a minimum value at 06:00 h. The mean reaction times increased non-significantly at the end of the night-shift and the results of the two Sternberg memory search tests showed no significant trends. The sleep of the operators after the night-shift was on average reduced to 5 hs 34 min. The results of subjective rating of alertness and reaction time test are interpreted as effects of the combined influences of circadian rhythmicity, sleep loss and time on professional task. Most results support the conclusion that a 14-h night-shift without extensive breaks is not acceptable.     

The relative influence of country conditions, industry structure, and business strategy on multinational corporation subsidiary performance

Two competing theories of firm performance have been proposed in the business strategy literature, the industry structure view and the resource-based view of the firm. Empirical studies have estimated the relative contribution of industry structure, corporate, and business unit effects to business unit performance. These studies, however, have been restricted to using only single-country data. Missing from this debate is an international dimension that includes the relative importance of country conditions as a determinant of firm performance. The objective of this article is to fill this void by adding country characteristics to the analysis. Using cross-country data of four large multinationals in a single industry, we estimate the relative importance of country characteristics in addition to industry structure, corporate characteristics, and subsidiary strategy as determinants of subsidiary performance by using multiple regression analysis. This analysis also will contribute to the discussion on environmental determinism versus strategic choice. Country and industry characteristics are mainly outside the control of management, whereas corporate characteristics and subsidiary strategy are under management's control. Results show that country characteristics are by far the most important determinant of subsidiary performance, followed by industry structure, subsidiary strategy, and corporate characteristics. Thus, country conditions are a very important determinant of firm performance that so far has been overlooked in previous studies. These results indicate that subsidiary performance is determined mainly by conditions outside the control of subsidiary management. In terms of competing theories, these results support the environmental determinism view more than the strategic choice view and the resource-based view of the firm more than the industry structure view. These results also have important implications for multinational corporations' selection of countries for entry and investment and for performance evaluation of subsidiary management.     

Theories of the Firm–Market Boundary

A central role of the entrepreneur-manager is assembling a strategic bundle of complementary assets and activities, either existing or foreseen, which when combined create value for the firm. This process of creating value, however, requires managers to assess which activities should be handled by the market and which should be handled within hierarchy. Indeed, for more than 40 years, economists, sociologists and organizational scholars have extensively examined the theory of the firm's central question: what determines the boundaries of the firm? Many alternative theories have emerged and are frequently positioned as competing explanations, often with no shortage of critique for one another. In this paper, we review these theories and suggest that the core theories that have emerged to explain the boundary of the firm commonly address distinctly different directional forces on the firm boundary—forces that are tightly interrelated. We specifically address these divergent, directional forces—as they relate to organizational boundaries—by focusing on four central questions. First, what are the virtues of markets in organizing assets and activities? Second, what factors drive markets to fail? Third, what are the virtues of integration in organizing assets and activities? Fourth, what factors drive organizations to fail? We argue that a complete theory of the firm must address these four questions and we review the relevant literature regarding each of these questions and discuss extant debates and the associated implications for future research.     

An Integrated Methodology for Assessment and Selection of the Project Risk Response Actions

In a systematic process of project risk management, after risk assessment is implemented, the risk analysts encounter the phase of assessment and selection of the project risk response actions (RA). As indicated by many researchers, there are less systematic and well-developed solutions in the area of risk response assessment and selection. The present article introduces a methodology including a modeling approach with the objective of selecting a set of RA that minimizes the undesirable deviation from achieving the project scope. The developed objective function comprises the three key success criteria of a project, namely, time, quality, and cost. Our model integrates overall project management into the project risk response planning (P2RP). Furthermore, the proposed model stresses on an equivalent importance for both "risk" and "response." We believe that applying the proposed model helps the project risk analyst in most effective and efficient manner dealing with his or her complicated RA selection problems. The application of the proposed model was implemented in projects in the construction industry in which it showed tremendous time, cost, and quality improvements.