Extending Little’s Law to single order throughput times

It has long been established that the mean throughput time is a result from the relationship between the work in process (WIP) and output rate. In reality, however, throughput times are frequently dispersed broadly around this mean. With the aid of a model originally developed for lateness, it is now possible to describe the throughput times of individual orders. Accordingly, the throughput time can be divided into two components: WIP-dependent throughput time and sequence-dependent throughput time.     

Tweaking the entrepreneurial orientation–performance relationship in family firms: the effect of control mechanisms and family-related goals

Management literature is currently giving growing conceptual and empirical attention to the peculiarity and relevance of entrepreneurial attitudes in family firms, with divergent outcomes. Aiming at concretizing the effects of these attitudes, denoted by the entrepreneurial orientation construct, on family business performance and considering that family dynamics come into play in this relationship, we particularly investigate the impact of control mechanisms and family-related goals. Findings are based on a sample of 180 family firms and show that Proactiveness and Autonomy are particularly relevant to financial performance. Agency-problems avoiding control mechanisms moderate the effect of Innovativeness and Autonomy, while socioemotional wealth (SEW) goals moderate the effect of Risk-Taking, respectively. The usage of these mechanisms and managing SEW goals provide opportunities for a more efficient exploitation of entrepreneurial attitudes.     

Flight gate scheduling: State-of-the-art and recent developments

This paper surveys a large variety of mathematical models and up-to-date solution techniques developed for solving a general flight gate scheduling problem that deals with assigning different aircraft activities (arrival, departure and intermediate parking) to distinct aircraft stands or gates. The aim of the work is both to present various models and solution techniques which are available in nowadays literature and to give a general idea about new open problems that arise in practise. We restrict the scope of the paper to flight gate management without touching scheduling of ground handling operations.     

Shortest and longest length of success runs in binary sequences

The shortest and the longest length of success runs statistics in binary sequences are considered. The sequences are arranged on a line or on a circle. Exact probabilities of these statistics are derived, both in closed formulae via combinatorial analysis, as well as recursively. Furthermore, their joint probability distribution function and cumulative distribution function are obtained. The results are developed first for Bernoulli trials (i.i.d. binary sequences), and then they are generalized to the Polya–Eggenberger sampling scheme. For the latter case, the length of the longest success run is related to other success runs statistics and to reliability of consecutive systems.     

Innovation and Sectoral Employment: A Trade–off between Compensation Mechanisms

The question whether technological progress displaces employment or whether technological advance is beneficial for the level of employment has been at the core of economic debate for over two centuries. The beneficial effect might be achieved by several compensation mechanisms within the economic system. In this paper we categorize these compensation mechanisms into two basic categories that reflect the different nature of the ideas ruling the compensation. We discriminate the mechanisms of employment despite innovation from employment via innovation. In the context of new innovation economics we model an artificial industry implementing both compensation mechanisms. Simulation analysis is used to examine both the short–run and long–run properties of the model. There we focus on the influence of wage restraint policy on the functioning of the compensation mechanism.     

Interactive Job Shop Scheduling: An Experiment

An experiment is discussed in which three computer-aided, interactive job shop scheduling approaches are compared using an interactive job shop scheduling simulator (JOB) developed for the project. All three approaches use a combination of computer and human capabilities to develop job shop schedules, but differ in terms of the timing and degree of human involvement required. The three scheduling approaches are (1) the successive approach, (2) the interactive approach, and (3) the semi-interactive approach. The successive approach is characterized by the computer scheduling all work orders without any human intervention. The interactive approach is distinguished by the human scheduling one work order at a time until all work orders are scheduled. The schedule is developed interactively by the person who must simultaneously consider work-order scheduling needs and machine group load capacities. The semi-interactive approach may be viewed as a combination of the successive and interactive approaches. Work orders are automatically scheduled one at a time using the successive approach criteria, but with prespecified machine-group load thresholds. As long as the load threshold is not exceeded, the successive approach is used to schedule work orders. When a threshold is exceeded, the algorithm (successive approach) pauses and human rescheduling (interactive approach) is required to rectify the overload situation. A second (reallocation) phase, identical for all three approaches, is used to overcome any scheduling problems generated in phase one. Experimental results based on nine different performance criteria (including scheduling time, makespan, machine group utilization, and work-in-process inventory) and 45 experimental runs indicate that there are differences between the results produced by the three scheduling approaches. The interactive approach yields the best overall scheduling results, but the other two approaches are clearly better than the interactive approach in some situations. The success of the interactive approach indicates that it is usually best for the human scheduler to become involved early in the computer-based job shop scheduling process.     

A SIMULATION STUDY OF DECENTRALIZED DECISION MAKING*

This study develops a heuristic procedure for decision making coordination in a decentralized organization structure. The procedure consists of simplified rules of iterative communication between decentralized units and a central agent. The central agent assigns budgeted profit levels and adjusts such levels guiding the system toward optimality. The decision making procedure developed in this study is compatible with management by objectives practices and can serve as a prototype for decentralized management.