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Malnutrition is a serious obstacle to development in many countries. To deal with it effectively we must know how to provide adequate nutrition in an economical way. Linear programming will determine the most economical set of foods or production activities if the set of nutrients needed can be specified in absolute amounts or as fixed ratios, but this will not suffice for one of the most pressing nutritional problems--the protein problem. It is impossible to specify the quantity of protein required in this way. That quantity depends upon the concentration of protein in the diet and the "quality" of the protein (its amino acid composition). The greater the concentration, the less efficiently the protein is used; the better the quality, the more efficiently. For a least-cost diet, quality and quantity must be determined simultaneously, but the relationships are nonlinear. This paper presents a model, with one nonlinear restraint, that determines a least-cost diet in which the quality and the quantity of the protein are jointly and optimally determined. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to describe a mathematical model, called MOD-METRIC, for the control of a multi-item, multi-echelon, multi-indenture inventory system for recoverable items, that is, items subject to repair when they fail. Discussion is limited to two-echelon multi-item systems in which an item may be demanded at any one of several locations called bases; in turn, these bases receive inventory from a central location called a depot. The objectives of the model are to describe the logistics relationship between an assembly and its subassemblies, and to compute spare stock levels for both echelons for the assembly and subassemblies with explicit consideration of this logistics relationship. In particular, the model is used to determine the base and depot spare stock levels which minimize total expected base backorders for the assembly subject to a system investment constraint. An example is given showing how the model can be used to calculate spare engine and engine module stock levels. MOD-METRIC has been implemented by the Air Force as the method for computing recoverable spare stock levels for the F-15 weapon system. [ABSTRACT FROM AUTHOR]

This paper examines the nature and promise of the revolutionary approach to social problems that is represented by systems analysis. It first describes social decisions and how they are usually made. Then it examines systems analysis, considers its worth for social decisions, and describes some prerequisites required for it to be useful. Finally, the paper concludes that systems analysis of social problems can contribute substantially to the intelligent allocation of society's resources. [ABSTRACT FROM AUTHOR]

This paper discusses an inventory system in which the cost per order varies and is dependent on the number of different items listed on the order The problem is to determine how frequently orders should be initiated and how many different items should be listed on the orders so as to minimize the sum of the costs of carrying inventories and the costs of ordering An area for application of this study is discussed and models are developed for various ordering policies Examples are given and the costs associated with each of these policies are compared [ABSTRACT FROM AUTHOR]

This article discusses the author's opinion on how economic models are represented in professional journals in the U.S. The author criticizes the lack of relevance in the current academic teaching and research in economics. The author emphasized on the political influence of the lack of empirical foundation in speculative economic theory. The author postulated that the representation of a new model of economics is usually centered on a step-by-step derivation of its formal properties. However, policy oriented models are gaining favor over descriptive ones. The author then concluded that the Establishment of systematic cooperative relationships across the traditional frontiers now separating economics from these adjoining fields is hampered by the sense of self-sufficiency resulting from what is characterized as undue reliance on indirect statistical inference as the principal method of empirical research.

The article focuses on operations research, a decision making mathematical method. According to the author, operations research is not a subject-matter field but an approach or method. And, even after a study of hundreds of examples of work classified as operations research, it is by no means clear just what the method is other than that it is scientific, because operations analysts are typically resourceful and ingenious men who tackle their problems with no holds barred. There is an important corollary to the tendency of operations analysts to cast their thinking in terms of formal mathematical models. Operations research is not a descriptive science but a prescriptive one. Therefore the deduction of adequate descriptive models is only part of the task of the operations analyst. In the end he must come up with a recommendation for action and this requires that he know what the operation in question is intended to accomplish. The economist comes to operations research with a number of important ideas already instilled, among them an appreciation of the importance of substitution, a sophistication about the objectives of enterprises, an awareness of the importance of marginal trade-offs, and most important, a realization that physical quantifies are subsidiary to "values" in a decision process. He also inherits from his training a number of disabilities, including ignorance of the technical side of business and industry and a belief in the existence of production functions.

A nonmathematical model is developed of one type of community, termed the "folk village." Ten villages, each from a different culture, provide the only data, and the model's nineteen components are based on traits found in all the villages. The components (or subelements) are grouped into elements of interaction, space, activities, sentiment, and norms. The more variable components are eliminated as possible integrating factors, on die premise that the nature of the folk village resides in its constants. One means of integrating the components is offered in tile definition: The folk village is a localized system of co-operating families. (Co-operation is institutionalized as mutual aid.) This definition furnishes a basis for describing the elements as they appear in the villages. The findings are used as limiting factors in evaluating earlier concepts. Selected definitions of community are reexamined, and the relation of the model to Redefined's folk society is briefly indicated. [ABSTRACT FROM AUTHOR]

Using Bayesian probability theory and Ackoff's Behavorial Theory of Communication, a mathematical model of the Hegelian Dialectical Inquirer is developed. The model strongly argues against the widely held and naive distinction between "fact" and "theory." The model strongly argues for a new way of treating statistical data, in a sense, for a "new" theory of statistics. A fundamental principle of the Hegelian Inquirer is formalized, i.e., that one only stands to understand any issue by witnessing the strongest possible kind of debate take place on that issue. The model suggested is one that is seen as especially suited to issues involved in Strategic Planning. [ABSTRACT FROM AUTHOR]

This paper discusses models for planning the social development of a country. These models are intended to provide some understanding and assessment of intertemporal changes in social groups through industrial, educational, health, etc. opportunities and constraints over a time horizon. They thus include constraints and goals for planning the improvement in living conditions and the upgrading of different segments of society. The models also make extensive use of various sociological factors. While these models are presented in the context of a developing nation, the concepts, attributes and formalisms are not limited to such cases. [ABSTRACT FROM AUTHOR]

Numerous alternatives are available in the kinds of studies which can be elected in the market research which should precede the introduction of a new product. This gives rise to a possible network interpretation and treatment by an associated chance-constrained programming characterization and analysis. The resulting model, called DEMON (Decision Mapping Via Optimum GO-NO Networks), which was discussed in [6], is here given a new formulation in terms of an extremal equation. A general analytic characterization is achieved and then replaced by more special ones. Means for effecting study decisions and inferences are discussed along with the sensitivity analyses that we associate with GO and NO preemptions, relative to profit and payback constraints. Payback (in a constraint) is here distinguished from its use as a criterion for choice (or objective), the latter being here oriented toward MEMP (maximizing expected maximum profit). A chart is provided for interpreting these and other aspects of policy which bear on the problems of marketing a new product. [ABSTRACT FROM AUTHOR]

This paper applies, to ballistic missile systems, replacement policies for equipment subject to stochastic failures in which the actual state of the system--good or failed--is not known with certainty. Although it applies these policies only to the missile itself, optimal maintenance policies for the system as a whole are conceptually similar. The criterion employed for comparison of alternative maintenance policies is to minimize the total cost per expected piece of equipment good per period of time. Maximization of system reliability is a special case of this criterion which ignores the financial costs of maintenance actions. The range of maintenance policies examined may be subdivided in two ways. First, it may be assumed that the distribution of times to failure for parts not subject to inspection is known. Secondly, it may be assumed that the distribution is known but that one or more parameters characterizing the distribution are unknown. The central feature of these latter policies is that the interval between replacements is adapted to new information as it accumulates. A second subdivision encompasses those maintenance policies in which the time to replacement for the non-monitored part depends on the state of the remaining parts of the system, and those in which only the failure rate of the uninspected part and the cost of maintenance actions are taken into account in determining the replacement interval. The first class of policies is called "opportunistic," since optimal policies are designed to take advantage of opportunities arising through failures of the remaining parts. Opportunistic policies have a structure which may be described by a critical number N and a set of such critical numbers n1, n2 ⋅⋅⋅, each corresponding to one of the parts under inspection. The optimal policy may be described as follows: For 0 ? x ? ni, the non-monitored part is not replaced if the i-th monitored part fails; for ni ? x ? N, the non-monitored part and the i-th monitored part are replaced whenever the i-th monitored part fails. For illustrative purposes, optimal policies of each type are computed for a hypothetical ballistic missile system. They are then compared with each other and with a rule of thumb frequently proposed for replacement policy. Replace at the mean time to failure. [ABSTRACT FROM AUTHOR]

Integrated steel mills usually have a choice over the use of various materials and production processes. Different ores may be used in the production of iron; steel scrap and iron can be used in different proportions in the production of steel. The economical usage rate of all materials is a function of numerous variables, among which the market price of some materials, notably of various grades of steel scrap, fluctuates and therefore requires a periodic determination of the economical usage rate. This is a typical problem for programming. The paper presents a mathematical formulation of the stages of iron and steel production to determine the optimal (least cost) rate of input of materials. The models of the various stages of production are connected to form a "master model" of an integrated steel mill. [ABSTRACT FROM AUTHOR]