Search

This paper provides the solution to the problem of the distribution of busy periods of the single-channel queue characterized by a time-dependent Poisson-distributed arrival rate and a general class of holding times. The notation is chosen in such a fashion that the main body of computations and mathematical analysis is identical with what was required in the solution of the general queuing equations considered in a previous paper which should be read first [4]. The solution of the problem for winch the traffic intensity is constant and the holding time distribution is Pearson type III is derived in closed form in terms of the Ink functions introduced previously. [ABSTRACT FROM AUTHOR]

The article reports on the discussion of the study concerning the learning of mathematics. The discussion contains arguments regarding the paper written by professor Stone about functions. One of the arguments that is given attention to, is the concept of function being connected with the primitive concepts of pure logic, nearly unanalyzable and must be grasped by a psychological act of direct perception. This argument is also related to the child's development as the notion of grasping and perception are described to occur at some point in the development.

This paper sets forth mathematical means for optimizing the simultaneous apportionments of reliability and maintainability by means of two techniques Lagrange multipliers and dynamic programming. Since one of the constraint equations revolves allocating both variables, this simultaneous apportionment problem differs from the usual two-dimensional dynamic programming problems. Two cost problems are treated the first minimizes cost while satisfying availability requirements under the assumption that an unlimited ceiling exists for the cost, and the second maximizes reliability and maintainability given a fixed budget. Although these problems appear closely related, step functions usually preclude considering them together The paper also considers two numerical examples, an interesting cost model for maintainability, and using computers with its models. [ABSTRACT FROM AUTHOR]

The main object of the paper is to demonstrate a method by which a number of problems arising in the study of impatient customers in queues can be solved. The main difficulty in analyzing such queuing systems is the presence of variable coefficients in the difference-differential equations describing the processes; the usual generating function method fails in such cases. When there is a finite number of states, it has been shown that at least formal solutions can be obtained through matrix algebra, which yields what are called 'discrete transforms.' The results are explicitly given when the balking and reneging coefficients are linear in n. An alternative method in which the spectral resolution of matrices is used is also given for solution of the set of equations. In the special case of a M/G/1 queue with finite waiting room, both the methods fail (as the underlying matrix is in the Jordan form), and the solution is obtained by a simple manipulation of the underlying matrix. The methods presented here lend themselves readily to computer solutions. This paper demonstrates the generality of the basic M/G/1 model by relating it to problems arising in other branches of operations research, such as reliability theory, inventory control, etc. Finally, the methods used for the M/G/1 case are shown to hold for a similar class of problems in the GI/M/1 case. As very little work has been reported on impatient customer phenomena in GI/M/1, systems, possibly because of the difficulty in solving equations with variable coefficients, this method may prove to be useful. [ABSTRACT FROM AUTHOR]

The approach to the traffic-flow problem based on an integral differential equation of the Boltzmann type which has been considered by one of us in a recent paper is further developed. The possibility of passing is explicitly introduced into the equation for the velocity distribution function. As in the previous paper, it is shown that at sufficiently high concentration a collective flow process must take place. In order to study more specifically the effects of one car on another, we define reduced n-car distribution functions giving the probability of finding a cluster of n cars all having the same velocity. We derive an equation for the evolution of this distribution function. Study of it yields some information as to the way traffic changes from relatively free flow to completely hindered, 'condensed' flow. [ABSTRACT FROM AUTHOR]

This paper considers an n-phase generalization of the typical M/M/1 queuing model, where the queuing-type birth-and-death process is defined on a continuous-time n-state Markov chain. It shows that many models analyzed in the literature can be considered special cases of this framework. The paper focuses on the steady-state regime, and observes that, in general, closed-form results for the limiting probabilities are circuit to obtain, if at all possible. Hence, numerical methods should be employed. For an interesting special case, explicit results are obtained that are analagous to the classical solutions for the simple M/M/1 queue. [ABSTRACT FROM AUTHOR]

This paper reviews the principal public literature concerned with expected profit decision-theoretic closed-competitive-bidding models. It makes extensions of previous formulations for static multi-contract bidding situations with and without cost dependencies and resource constraints. The same decision model is reformulated to utilize numerical, Lagrange multiplier, dynamic, and integer linear programming techniques according to the information available to the bidder. A zero-one integer programming formulation is well suited to utilize subjective probabilities of winning estimates. Finally, the paper suggests a format for further development. [ABSTRACT FROM AUTHOR]

This paper presents a new decomposition procedure that reduces the highspeed memory requirement and interpolations associated with the dynamic programming algorithm. It shows that an nth-order system described by h coupled difference on differential equations can be treated as a hth-order system with respect to the high-speed memory requirement and interpolations in the dynamic programming procedure. [ABSTRACT FROM AUTHOR]

This paper deals with the effect of promotional efforts in the previous periods on the sales in the present period. Differential equation approach has been used to study the relation between sales and promotional effort for multicompetitors and multiperiods. Using these relations, the problem of finding optimum promotional effort has been formulated for multiperiods, multicompetitors, and multiproducts. For the case of a single product, the optimal values have been obtained. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to provide a solution to a linear difference differential equation with time lag which governs the motion of a line of traffic. The idea of using operational calculus in solving such types of equations is not new, but the result may be of interest. In addition, a special problem is considered and some consequences derived from the solution. [ABSTRACT FROM AUTHOR]

The causal relationships in a two variable system are examined, using a simultaneous linear differential equation model. Emphasis is placed on the necessity for considering mutual interaction instead of looking for unidirectional causality. To demonstrate the usefulness of this approach an example is taken from the management science literature concerning the relationship between labour turnover and overtime. It is shown that, on certain assumptions, the data disconfirm a hypothesis previously thought to be confirmed. Certain informal observations made in the original paper were shown to receive confirmation from the data. [ABSTRACT FROM AUTHOR]

A theory is given for circumnutations in plants, especially hypocotyls of Helianthus annuus, which were used as experimental material. The theory is based on the lateral auxin transport, which arises when a gravitational force component acts on the plant. With a suitable time delay between stimulus and response, oscillations or circumnutations should arise. It is possible to describe these oscillation phenomena by the solutions of a differential equation, derived in this paper. The time delay has a central role in this equation. The time delay is assumed to be identical with the geotropic reaction time for the hypocotyls. The ratio between the periodic time for the circumnutations and the reaction time for geotropic curvatures was found to be approximately constant in the temperature region investigated (namely 15-40°C), which supports the theory. Different methods of recording the circumnutations were used, 8 mm film camera technique being the most frequently employed. The introduction of a weighting function for describing the plants "memory" of the stimulation makes it possible to relate the periodic time of the circumnutations to the reaction time for geotropic curvatures. The necessity of this weighting function as well as of the time delay in the equations is emphasized. An explanation of the "Fünfphasenbewegungen", reported in the literature, is presented. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Production Research is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper a Monte Carlo sampling study consisting of four experiments is described. Two error distributions were employed, the normal and the Laplace; and two small sample sizes (20 and 40) were tested. The question of simultaneousequation bias called for two-stage estimators. The L1 norm was employed as a means of comparing the performance of the L2 or least squares estimators. A relatively new algorithm for computing the direct least absolute (DLA) and two-stage least absolute (TSLA) estimators was employed for the experiments. The results confirmed the hypotheses that for non-normal error distributions such as the Laplace the least absolute estimators were better. [ABSTRACT FROM AUTHOR]

A sparse matrix is defined to be a matrix containing a high proportion of elements that are zeros. Sparse matrices of large order are of great interest and application in science and industry; for example, electrical networks, structural engineering, power distribution, reactor diffusion, and solutions to differential equations. While conclusions within this paper are primarily drawn considering orders of greater than 1000, much is applicable to sparse matrices of smaller orders in the hundreds. Because of increasing use of large order sparse matrices and the tendency to attempt to solve larger order problems, great attention must be focused on core storage and execution time. Every effort should be made to optimize both computer memory allocation and execution times, as these are the limiting factors that most often dictate the practicality of solving a given problem. Indexing algorithms are the subject of this paper, as they are generally recognized as the most important factor in fast and efficient processing of large order sparse matrices. Indexing schemes of main interest are the bit map, address map, row-column, and the threaded list. Major variations of the indexing techniques above mentioned are noted, as well as the particular indexing scheme inherent in diagonal or band matrices. The concluding section of the paper compares the types of methods, discusses their suitability for different types of processing, and makes suggestions concerning the adaptability and flexibility of the major existing methods of indexing algorithms for application to user problems. [ABSTRACT FROM AUTHOR]

This paper establishes necessary and sufficient conditions for constraint set stability requiring neither convex constraint functions nor convex constraint sets. These conditions then lead to a sufficiency result for the continuity of the optimal objective values as the right-hand side varies. Applications to quasiconvex functions are presented. [ABSTRACT FROM AUTHOR]

A duel is initiated by an attacker at some time t in [-- T, 0]. The defender possesses weapons at -- T and encounters 'false' targets that occur at time t with probability density λ(t) and are classified as 'real' with probability C[subfa]. At the time of attack, the probabilities that the attacker is detected and classified as real are D and c[subaa] (D, C[subaa], C[subfa] are constant). If the defender responds with one of his k weapons at the time of attack, he survives with probability p[subk], and, if he does not respond, he survives with probability q[subk]; q[subk]

The article discusses operations research in China. This type of research was emerged during the liberation of mathematics in the country. Under the leadership of the Chinese Communist Party, mathematics has striven forward. Linear programming, numerical analysis, mathematical statistics, and differential equations are the most important mathematical methods that have been applied. The essential achievement of this direction of research is not the results already attained but rather its profound influence for the future.

In certain problem areas it is not possible to establish one objective function. There may be several, sometimes conflicting, goals. This paper presents a method of reconciling such conflicting goals by establishing a global objective function. A combinatorial example is given and solved by "modified" dynamic programming. [ABSTRACT FROM AUTHOR]

The set of ordinary differential equations resulting from analysis of a lumped model of a microwave oscillator incorporating an n+pp+ IMPATT diode in a simple external circuit is solved using a standard predictor-corrector method. D.C. results suggest that a five lump model may be used to describe the diode behavior Investigation of the steady state oscillation properties of the circuit shows that the simple five lump model is valid at r.f. voltage swings less than 30% of the diode breakdown voltage. At higher r.f. swings more lumps are needed for accurate results.
This paper describes the derivation of a one dimensional lumped model for the IMPATT diode and external circuit which is sufficiently accurate to retain realistic diode physical parameters, yet simple enough to require minimum computer time. One comparison of the results of this large signal analysis with results obtained using a more complex program shows reasonable agreement (Giblin 1970). [ABSTRACT FROM AUTHOR]