We examine the effects of component commonality on optimal safety stock levels in a two-product, two-level inventory model. The criterion is to minimize system safety stock subject to a service level constraint. Although our model is specialized, its analysis provides insights not available in other multilevel inventory models.
In practice many data series contain observations at irregular times whereas most forecasting methods are restricted to the case of equal time intervals between data points. This paper provides extensions of Single Exponential Smoothing and Holt's Method to the case of irregularly spaced data and shows them to be highly efficient computationally. The new methods are applied to six published series, and their performance is analyzed via four error measures with respect to changes in the smoothing parameters.
Material Requirements Planning or Manufacturing Resource Planning (MRP) systems originally were designed for a deterministic environment. Often, however, demand for finished products is uncertain and some type of buffering mechanism is necessary to provide desired levels of service. When the schedule is replanned each period, as typically is done, variability of demand may manifest itself in the form of early or “emergency” production runs. Safety stock may serve to avert some or most of these emergency production runs. We have developed a heuristic algorithm which is shown to provide extremely good guidelines for setting safety stock levels.
This study examines the effects of frequency and centrality of communication on research and development project success. The data used in this study are from 49 government funded R & D projects in Afghanistan during 1979. The results of the multivariate analyses show that frequency of communication is positively correlated with performance for mid and high performing groups, centrality or location of the project within the communications network is negatively related with project performance within the low performance category. The results are consistent with the evidence thus far obtained for developed countries. There appears to be little difference in the effects of centrality and frequency of communication on the performance between research and development projects. This result is not consistent with the available evidence for developed countries. The results of the regressions on the socio-metric data suggest age are negatively correlated with communication centrality. This is due to the particular circumstances found in 1979 in Afghanistan where the older scholars were typically trained in the region while the younger scholars were mostly Western trained. While conceptually this study is indebted to the research concerning developed countries, these results imply that caution is mandated in generalizing the given body of knowledge to developing countries.
This paper discusses a class of natural organizational phenomena called virtual positions and links them to the enactment of power. Virtual positions involve three or more persons from different parts of an organization working together on a recurring (and usually major) task process. A virtual position is contrasted to a regular position in which an incumbent performs a set of task processes. There is no regular position for the task processes performed by a virtual position. Instead the set of individuals act as if they are a composite position. There are two types of virtual positions: regulated and unregulated. Regulated virtual positions usually take the form of committees, standing committees, and task forces. Unregulated virtual positions involve task processes which have been neither rationalized nor integrated with the Organizational Architecture. Virtual positions arise out of attempts to cope with organizational changes without having to redesign the organization. Given enough time a virtual position can be used to analyze change and to determine how it should be handled. But when changes occur at a more rapid rate than the virtual positions can be absorbed, they can spread rapidly. Thus an informal adaptive mechanism can lead to an accumulation of problems which can become maladaptive. Each virtual position involves the control of some task process and the possible leverage of this task process on others. Each virtual position participant has opportunity for access to information, other persons, and the possibility of enhancing his own position or preventing the enhancement of another's. When the virtual position involves major, recurring vulnerabilities, this control can be parlayed into organizational power. Virtual positions are viewed as arenas for power struggles in organizations. An example is given of the virtual positions in an actual community bank. The theory underlying the virtual positions is based on the continuing evolution of a theory of group structures. The concepts of process and task process are defined. A recently developed operationalization of the concept of interdependence is introduced. The notion of uncertainty is generalized. This leads to the development of uncertainty interdependence. Power is seen as the control of uncertainty interdependence. Virtual positions are viewed as the arenas in which uncertainty interdependencies can be resolved. Thus virtual positions are linked to the distribution and enactment of power in organizations. The theoretical discussion is based on a technology which is used in organizational design. Consequently, there exist means by which virtual positions can be identified and analyzed in real organizations. This paper links these analyses of virtual positions to the process of designing an organization.
In this paper we develop a resource planning and allocation model for a mental-health community-support system. The intent of the model is to provide a tool to system managers and planners to support resource planning and allocation decision-making. More and more, mental health care is being delivered by a variety of community-based service agencies instead of single, comprehensive institutions. The service needs of a client population are continually changing, and depend upon the relative functioning of the population, which depends upon the efficacy of the services provided. The availability of resources is becoming scarcer, and is more closely scrutinized. Consequently, the system manager must attempt to apply the available resources as effectively as possible. We develop a conceptual framework for planning that includes aggregating patients according to their functional level and service needs, and defining “service package options” for each aggregate patient group. We also estimate the effect of giving a particular service package to a patient group, in terms of functional improvement or regression. The planning problem is then to assign service packages to aggregate groups over a multi-period planning horizon to maximize some measure of system welfare within the available resources. This planning problem is a linear programming problem that we illustrate using representative data.
In order to determine an optimum sales strategy for a property it is useful to estimate the distribution of bids which will be received for the property. The more accurate the estimate of the distribution, the higher the expected return will be from following the optimal strategy. This paper presents a technique for estimating the parameters of that distribution based on order statistics. It also describes how a posted list price might affect the sale price data used in this estimation technique, and how the technique can be modified to deal with this type of censored data.
With growing austerity pressures from the Administration, Congress, and the general public, the Government's procurement policy has called for increased use of dual-source competition as a means of reducing acquisition costs. In practice, however, this policy has produced mixed results. The cause seems to be an inadequate understanding of the peculiarities of competition in the Government's market. This paper examines the risk and return available in the defense market, and relates it to the industry's propensity to compete. The results show that intelligent observation of the industry's capacity utilization rate would contribute to the development of a more efficient acquisition policy.
A central issue in new product development and planning is the market timing/entry decision. An entry too early may risk pushing an under-developed product into the marketplace, with possible negative results; however, a product/technology may sacrifice sales if entry is delayed too long. A market diffusion model is developed that incorporates negative word-of-mouth associated with new product failure, resulting from premature introduction. Our analysis suggests that, when introducing a new technology, significant penalties may be associated with mistiming introduction. The analysis was applied to a problem facing the photovoltaic program of the Department of Energy. A proposal to construct a 100-home demonstration program for photovoltaics (PV) in the Southwest was being evaluated. The analysis of this case showed that an argument can be made to delay the demonstration program for several years and that significant risks (in terms of lowered ultimate market penetration) exist when starting this PV demonstration program prematurely.