摘要:

AbstractIn this article, we investigate the dynamics of software development productivity throughout the software development lifecycle. Our investigation discerns three forms of productivity, namely, potential, actual, and perceived. This conceptual dissection of productivity provides a useful lens for focusing on two distinct sets of managerial concerns: losses in the efficiency of software production, and losses in the effectiveness of managerial control. Losses in production efficiency stem from faulty processes associated with motivation and communication and lead to a gap between potential productivity and actual productivity. Losses in the effectiveness of managerial control arise, particularly in the early stages of a software project, from the discrepancy between what management perceives productivity to be and what it actually is.

ISSN:0883-7066    

DOI:10.1002/sdr.4260050202

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractUnemployment is at present one of the main economic problems in most Western countries. Shortening working hours and lowering retirement age have both been proposed as useful means of reducing this problem. Discussion of these measures has been conducted mainly at the macroeconomic level, however, and the consequences of such policies on the labor market have been evaluated differently by employers' groups and labor unions. These different evaluations clearly reflect conflicting political viewpoints but may also arise from the fact that little economic research has been performed in this field. To assess the economic implications of shortening working hours, the author has undertaken a microeconomic investigation to identify the dynamic consequences, especially on staff recruitment and on labor‐capital substitution. This article describes the basic structure of the system dynamics model applied in the stud

ISSN:0883-7066    

DOI:10.1002/sdr.4260050203

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe usefulness of control theory techniques in economic simulations is examined. A model of the capital investment accelerator is used for illustration. It is shown that behavior approaching optimality can be achieved in a highly nonlinear system with simple heuristics based on linearization and constant state feedback with an appropriate choice of desired closed‐loop poles. Applications to real‐life situations are discussed, and suggestions are made for approaching potential problems using similar control theory techniq

ISSN:0883-7066    

DOI:10.1002/sdr.4260050204

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractIn this article we develop a formal method, the reference approach, that can be used as a tool for policy optimization in a system dynamics model. The obtained policy is expressed in terms of feedback loops, which master the behavior of the system so that it reaches a dynamic according to the objectives of the designer.The reference approach utilizes three models: a system dynamics model, a reference model, and a control model. The first one is built using Forrester's principles. The second is a large optimization nonlinear model whose solution yields the dynamic desired by the planner. The third is a linear quadratic optimal control model with closed‐loop solution, which minimizes the gap between the observed dynamic (in the system dynamics model) and the desired dynamic expressed by the reference model.We illustrate the operation of the reference approach by using it to find the optimal policy of a well‐known system dynamics model. For this same model the best policy obtained with a heuristic approach is known. Finally, we compare the performance of these two polic

ISSN:0883-7066    

DOI:10.1002/sdr.4260050205

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThis article develops a modeling framework that allows a formal description of evolutionary processes in social and biological systems. An enumerable set of fields (chemical sorts, biological species, technologies, areas of scientific endeavor, and so on) is considered, each field being characterized by the number and properties of its representatives (occupying elements). By introducing probabilities for the elementary processes of spontaneous generation, identical self‐reproduction, error reproduction, death, and transition to other fields, we define a Markov process in occupation number space. At any time, only a finite set of fields is occupied, and the appearance of a representative of a field with “better” properties produces an instability in the system. The characteristic dynamics of such “innovative instabilities” are investigated by simulation. As a particular example, we consider the nonlinear growth properties associated with the emergence of new areas of scientific

ISSN:0883-7066    

DOI:10.1002/sdr.4260050206

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractNotes and Insightsis a forum for discussion and debate about current issues in the philosophy and application of the system dynamics approach, and a marketplace for the exchange of information about current research, policy issues, and teaching experiences. Manuscripts treating material particularly suited to presentation in short form (less than 2,000 words) should be sent to Erich Zahn, Betriebswirtschaftliches Institut, Abt. IV, Universität Stuttgart, Keplerstr. 17, D‐7000 Stuttgart 1, F.R

ISSN:0883-7066    

DOI:10.1002/sdr.4260050207

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractIn this section theSystem Dynamics Reviewpresents problems having the potential to stimulate system dynamics research. Articles may address real‐world dynamic problems that could be approached fruitfully from the system dynamics perspective, or methodological problems affecting the field. A paper submitted to theResearch Problemssection should concisely motivate and define a problem and start a process of conceptualization or formulation that can open the way for further studies. Manuscripts not exceeding 2,000 words should be sent to George P. Richardson, Milne 308, Rockefeller College, S.U.N.Y., Albany, NY 12222, U.S.

ISSN:0883-7066    

DOI:10.1002/sdr.4260050208

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractThis section of theSystem Dynamics Reviewis an eclectic source of information on items of interest to the system dynamics community. Conferences, articles, books, dissertations, speeches, software and hardware products, and teaching materials will be mentioned in this space. The purpose of the section is to provide summaries to help the system dynamics community keep abreast of recent progress related to the field and to anticipate important future events. Submissions covering a wide range of areas and information of possible interest to system dynamicists are encouraged, and should be sent to R. Joel Rahn, Faculté des Sciences de l'Administration, Université Laval, Ste. Foy, Quebec, G1K 7P4, Canad

ISSN:0883-7066    

DOI:10.1002/sdr.4260050209

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

ISSN:0883-7066    

DOI:10.1002/sdr.4260050210

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

ISSN:0883-7066    

DOI:10.1002/sdr.4260050211

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY