bluuebunny/crossref_metadata_2025 huggingface dataset:
On the economic application of airlift to product distribution and its impact on inventory levels
Authors: Gross Donald , Soriano A.
Published: May 2007

In many resupply situations, the decisionmaker has the option of “purchasing” faster replenishment leadtimes. For example, a premium may be paid for delivery by parcel post rather than slower but less expensive delivery by railway express. It may be economically advantageous to pay shipment premiums for faster leadtimes when considering the possible cost reductions in pipeline (on‐order) inventory and safety stock levels. This paper develops a decision rule which, for any given item, will indicate whether it is economically advantageous to purchase a faster leadtime. The general methodology is then applied to a peacetime military resupply operation involving several million items, each requiring a decision as to whether the item should be shipped by air or sea.
Duality in fractional programming
Authors: Kydland Finn
Published: May 2007

This paper develops theoretical and computational aspects of the dual problem in linear fractional programming. This is done on the basis of two alternative methods for solving the primal fractional programming problem, both of which were presented in earlier literature. Parametric changes in the resource‐vector are considered, and attention is given to infinitesimal as well as to discrete changes.
A probabilistic evaluation of helicopter lift capability
Authors: Limaye Dilip R. , Levy Edwin
Published: May 2007

This paper describes a technique for the calculation of the probability that a helicopter can lift a specified load, or number of loads with a specified frequency distribution, in a given geographical region. This probability is computed by determining the bivariate altitude‐temperature probability distribution for the specified region. The payload capability at any given temperature and altitude is calculated from standard performance equations. By integrating this over the altitude‐temperature distribution, it is possible to obtain the probability distribution of payload capability, from which the required probabilities of lifting specific loads can be determined.
On sequencing with earliest starts and due dates with application to computing bounds for the (n/m/G/Fmax) problem
Authors: Bratley Paul , Florian Michael , Robillard Pierre
Published: May 2007

Recent efforts to improve lower bounds in implicit enumeration algorithms for the general (n/m/G/Fmax) sequencing problem have been directed to the solution of an auxiliary single machine problem that results from the relaxation of some of the interference constraints. We develop an algorithm that obtains optimal and near optimal solutions for this relaxed problem with relatively little computational effort. We report on computational results achieved when this method is used to obtain lower bounds for the general problem. Finally, we show the equivalence of this problem to a single machine sequencing problem with earliest start and due date constraints where the objective is to minimize the maximum lateness.
Inventory models with a mixture of backorders and lost sales
Authors: Montgomery Douglas C. , Bazaraa M. S. , Keswani Ajit K.
Published: May 2007

This article presents several single‐echelon, single‐item, static demand inventory models for situations in which, during the stockout period, a fraction b of the demand is backordered and the remaining fraction 1 ‐ b is lost forever. Both deterministic and stochastic demand are considered. although the case of stochastic demand is treated heuristically. In each situation, a mathematical model representing the average annual cost of operating the inventory system is developed. and an optimum operating policy derived. At the extremes b=1 and b=0 the models presented reduce to the usual backorders and lost sales cases, respectively.
Bounds on the availability function
Authors: Butterworth Richard W. , Nikolaisen Tor
Published: May 2007

This paper gives bounds on the availability function for an alternating renewal process with exponential failure and general repair times. A bound on the error is also given. Several of the bounds with greatest practical consequence are worked out and illustrated. Repair distributions for which a lower bound on availability is easily computed are gamma (integer shape parameter), log normal, and Weibull. Finally, some simulation results for log normal repair versus gamma repair are given.
A continuous submarine versus submarine game
Authors: Langford Eric
Published: May 2007

This paper analyzes, from a game‐theoretic standpoint, the simultaneous choice of speeds by a transitor and by an SSK which patrols back and forth perpendicular to the transitor's course. Using idealized acoustic assumptions and a cookie‐cutter detection model which ignores counterdetection, we are able to present the problem as a continuous game, and to determine an analytic solution. The results indicate that with these assumptions, there are conditions under which neither a “go fast” nor a “go slow” strategy is optimal. The game provides a good example of a continuous game with a nontrivial solution which can be solved effectively.
Total optimality of incrementally optimal allocations
Authors: Stone Lawrence D.
Published: May 2007

This paper considers the problem of finding optimal solutions to a class of separable constrained extremal problems involving nonlinear functionals. The results are proved for rather general situations, but they may be easily stated for the case of search for a stationary object whose a priori location distribution is given by a density function on R, a subset of Euclidean n‐space. The functional to be optimized in this case is the probability of detection and the constraint is on the amount of effort to be used

Suppose that a search of the above type is conducted in such a manner as to produce the maximum increase in probability of detection for each increment of effort added to the search. Then under very weak assumptions, it is proven that this search will produce an optimal allocation of the total effort involved. Under some additional assumptions, it is shown that any amount of search effort may be allocated in an optimal fashion.
An explicit general solution in linear fractional programming
Authors: Charnes A. , Cooper W. W.
Published: May 2007

A complete analysis and explicit solution is presented for the problem of linear fractional programming with interval programming constraints whose matrix is of full row rank. The analysis proceeds by simple transformation to canonical form, exploitation of the Farkas‐Minkowki lemma and the duality relationships which emerge from the Charnes‐Cooper linear programming equivalent for general linear fractional programming. The formulations as well as the proofs and the transformations provided by our general linear fractional programming theory are here employed to provide a substantial simplification for this class of cases. The augmentation developing the explicit solution is presented, for clarity, in an algorithmic format.
Estimation of a hidden service distribution of an M/G/∞ system
Authors: George Laurence Lee , Agrawal Avinaeh C.
Published: May 2007

The maximum likelihood estimator of the service distribution function of an M/G/∞ service system is obtained based on output time observations. This estimator is useful when observation of the service time of each customer could introduce bias or may be impossible. The maximum likelihood estimator is compared to the estimator proposed by Mark Brown, [2]. Relative to each other, Brown's estimator is useful in light traffic while the maximum likelihood estimator is applicble in heavy trafic. Both estimators are compared to the empirical distribution function based on a sample of service times and are found to have drawbacks although each estimator may have applications in special circumstances.
Decision rules for attacking targets of opportunity
Authors: Mastran David V. , Thomas Clayton J.
Published: May 2007

Frequently in warfare, a force is required to attack a perishable enemy target system ‐ a target system where the targets are detected seemingly at random, and if not immediately attacked, will shortly escape from detection. A conflicting situation arises when an attack element detects a target of relatively low value and has to decide whether to expend his resources on that particular target or to wait for a more lucrative one, hoping one will be found. This paper provides a decision rule giving the least valued target that should be attacked as well as the resources that should be expended as a function of the attack element's remaining mission time.
Optimal and suboptimal procedures in group sequential sampling
Authors: Spahn M. , Ehrenfeld S.
Published: May 2007

This paper investigates the problem of choosing between two simple hypothesis, H0 and H1, in terms of independent, identically distributed random variables, when observations can be taken in groups. At any stage in the decision process it must be decided whether to stop and take action now or to continue, in which case the size of the next group of observations must be decided upon. The problem is to find an optimal procedure incorporating a stopping, group size (batch) and terminal action rule.

It is proven, in general, that the optimal stopping and terminal action rule is of the sequential probability ratio type (SPRT). Fixed stopping rules of the SPRT type are studied and an iterative procedure of the policy improvement type, both with and without a value determination step, is developed. It is shown, for the general situation, that both the average risk and scheduling rule converge to the optima. Also, six suboptimal scheduling rules are considered with respect to the average risks they achieve. Numerical results are presented to illustrate the effectiveness of the procedures.
A generalized euclidean procedure for integer linear programs
Authors: Richmond Tyronza R. , Ravindran Arunachalam
Published: May 2007

This paper investigates a new procedure for solving the general‐variable pure integer linear programming problem. A simple transformation converts the problem to one of constructing nonnegative integer solutions to a system of linear diophantine equations. Rubin's sequential algorithm, an extension of the classic Euclidean algorithm, is used to find an integer solution to this system of equations. Two new theorems are proved on the properties of integer solutions to linear systems. This permits a modified Fourier‐Motzkin elimination method to be used to construct a nonnegative integer solution. An experimental computer code was developed for the algorithm to solve some test problems selected from the literature. The computational results, though limited, are encouraging when compared with the Gomory all‐integer algorithm.
The development and evaluation of a cost‐based composite scheduling rule
Authors: Aggarwal Sumer C. , McCarl Bruce A.
Published: May 2007

A cost‐based composite scheduling rule is developed and evaluated in comparison with three other well‐researched scheduling rules—SPT, S/OPN, and SST. This cost rule permits the optimization of more than one performance measure at a time. The priority number that is used for scheduling operations through each machine group is based on four separate performance measures—(1) In‐process Inventory, (2) Facilities Utilization, (3) Lateness, and (4) Mean Setup Time. The factorial experimental design involved three factor levels of loads, three factor levels of cost, and three factor levels of mean time. Analysis of variance was performed on each of the five output measures to study the effects of each of the three factors on each individual rule. Rank‐order comparisons between rules were also made; and, finally, general conclusions with regard to the effectiveness and flexibility of the Cost Rule were drawn.
A generalized recursive algorithm for a class of non‐stationary regeneration (scheduling) problems
Authors: Glover Fred , Klastorin Theodore D.
Published: May 2007

Recent efforts in the field of dynamic programming have explored the feasibility of solving certain classes of integer programming problems by recursive algorithms. Special recursive algorithms have been shown to be particularly effective for problems possessing a 0–1 attribute matrix displaying the “nesting property” studied by, Ignall and Veinott in inventory theory and by Glover in network flows.

This paper extends the class of problem structures that has been shown amenable to recursive exploitation by providing an efficient dynamic programming approach for a general transportation scheduling problem. In particular, we provide alternative formulations lor the scheduling problem and show how the most general of these formulations can be readily solved vis a vis recursive techniques.
Optimization in mixed‐integer space with a single linear bound
Authors: Lambe Thomas A.
Published: May 2007

The search for an optimal point in a mixed‐integer space with a single linear bound may be significantly reduced by a procedure resembling the Lagrangian technique. This procedure uses the coefficients of the linear bound to generate a set of necessary conditions that may eliminate most of the space from further consideration. Enumerative or other techniques can then locate the optimum with greater efficiency. Several methods are presented for applying this theory to separable and quadratic objectives. In the maximization of a separable concave function, the resulting average range of the variables is approximately equal to the maximum (integer) coefficient of the constraint equation.
The economic effects of inspector error on attribute sampling plans
Authors: Bennett G. Kemble , Case Kenneth E. , Schmidt J. W.
Published: May 2007

In this paper the effects of inspector error on a cost‐based quality control system are investigated. The system examined is of a single sampling plan design involving several cost components. Both type I and type II inspector errors are considered. The model employs a process distribution, thus assuming that a stochastic process of some kind governs the quality of incoming lots. Optimal plan design is investigated under both error‐free and error‐prone inspection procedures and some comparisons are made.
Two machine flow shop scheduling problems with sequence dependent setup times: A dynamic programming approach
Authors: Corwin Burton D. , Esogbue Augustine O.
Published: May 2007

This paper considers the two different flow shop scheduling problems that arise when, in a two machine problem, one machine is characterized by sequence dependent setup times. The objective is to determine a schedule that minimizes makespan. After establishing the optimally of permutation schedules for both of these problems, an efficient dynamic programming formulation is developed for each of them. Each of these formulations is shown to be comparable, from a computational standpoint, to the corresponding formulation of the traveling salesman problem. Then, the relative merits of the dynamic programming and branch and bound approaches to these two scheduling problems are discussed.
Large deviations of the winsorized mean of an exponential distribution
Authors: Book Stephen A.
Published: May 2007

An asymptotic representation for large deviation probabilities of the Winsorized mean of a sequence of independent, identically distributed exponential random variables is derived. The Winsorized mean, a linear combination of exponential order statistics, is first transformed into a weighted sum of exponential random variables, and then a large deviation theorem for weighted sums can be applied. The representation obtained is then compared with results already known for the mean and the median, the two extreme cases of the Winsorized mean.
Target selection in lanchester combat: Heterogeneous forces and time‐dependent attrition‐rate coefficients
Authors: Taylor James G.
Published: May 2007

We develop solutions to two fire distribution problems for a homogeneous force in Lanchester combat against heterogeneous enemy forces. The combat continues over a period of time with a choice of tactics available to the homogeneous force and subject to change with time. In these idealized combat situations the lethality of each force's fire (as expressed by the Lanchester attrition‐rate coefficient) depends upon time. Optimal fire distribution rules are developed through the combination of Lanchester‐type equations for combat attrition and deterministic optimal control theory (Pontryagin maximum principle). Additionally, the theory of state variable inequality constraints is used to treat the nonnegativity of force levels. The synthesis of optimal fire distribution policies was facilitated by exploiting special mathematical structures in these problems.
Optimal replacement under additive damage and other failure models
Authors: Taylor Howard M.
Published: May 2007

A machine or production system is subject to random failure. Upon failure the system is replaced by a new one, and the process repeats. A cost is associated with each replacement, and an additional cost is incurred at each failure in service. Thus, there is an incentive for a controller to attempt to replace before failure occurs. The problem is to find an optimal control strategy that balances the cost of replacement with the cost of failure and results in a minimum total long‐run average cost per unit time. We attack this problem under the cumulative damage model for system failure. In this failure model, shocks occur to the system in accordance with a Poisson process. Each shock causes a random amount of damage or wear and these damages accumulate additively. At any given shock, the system fails with a known probability that depends on the total damage accumulated to date. We assume that the cumulative damage is observable by the controller and that his decisions may be based on its current value. Supposing that the shock failure probability is an increasing function of the cumulative damage, we show that an optimal policy is to replace either upon failure or when this damage first exceeds a critical control level, and we give an equation which implicitly defines the optimal control level in terms of the cost and other system parameters. Also treated are some more general models that allow for income lost during repair time and other extensions.
An operator theory of parametric programming for the generalized transportation problem: I. Basic theory
Authors: Balachandran V. , Thompson G. L.
Published: May 2007

This paper gives a new organization of the theoretical results of the Generalized Transportation Problem with capacity constraints. A graph‐theoretic approach is utilized to define the basis as a one‐forest consisting of one‐trees (a tree with an extra edge). Algorithmic development of the pivot‐step is presented by the representation of a two‐tree (a tree with two extra edges). Constructive procedures and proofs leading to an efficient computer code are provided. The basic definition of an operator theory which leads to the discussion of various operators is also given. In later papers we will present additional results on the operator theory for the generalized transportation problem based on the results in the present paper.
The knapsack problem: A survey
Authors: Salkin Harvey M. , De Kluyver Cornelis A.
Published: May 2007

A unifying survey of the literature related to the knapsack problem; that is, maximize \documentclass{article}\pagestyle{empty}\begin{document}$ \sum\limits_i {v_i x_{i,} } $\end{document}, subject to \documentclass{article}\pagestyle{empty}\begin{document}$ \sum\limits_j {w_i x_i W} $\end{document} and xi ⩾ 0, integer; where vi, wi and W are known integers, and wi (i = 1, 2, …, N) and W are positive. Various uses, including those in group theory and in other integer programming algorithms, as well as applications from the literature, are discussed. Dynamic programming, branch and bound, search enumeration, heuristic methods, and other solution techniques are presented. Computational experience, and extensions of the knapsack problem, such as to the multi‐dimensional case, are also considered.
Sensitivity of the (Q, R) inventory model to penalty cost parameter
Authors: Das Chandrasekhar
Published: May 2007

This paper treats an approximate continuous review inventory model with backlogging of excess demand and stochastic leadtime. The major result derived is that the behavior of the optimal order size with respect to the shortage cost parameter is determined solely by the “conditional mean residual life” function corresponding to the leadtime demand distribution. Some minor results and illustrative examples are also included.
A mean cost approximation for transportation problems with stochastic demand
Authors: Wilson Dan
Published: May 2007

Among the many tools of the operations researcher is the transportation algorithm which has been used to solve a variety of problems ranging from shipping plans to plant location. An important variation of the basic transportation problem is the transportation problem with stochastic demand or stochastic supply. This paper presents a simple approximation technique which may be used as a starting solution for algorithms that determine exact solutions. The paper indicates that the approximation technique offered here is superior to a starting solution obtained by substituting expected demand for the random variables.
Sensitivity of queueing models to the assumption of exponentiality
Authors: Gross Donald
Published: May 2007

This study deals with determining the effects on queuing models of assuming that interarrival and service times are exponentially distributed. Steady‐state expected value measures of congestion are compared for a variety of GI/G models when assuming an M/M model as an approximation. The majority of this effort involves single‐channel queues; however, some multichannel situations are also considered. In addition, effects of the exponential approximation are observed in certain cost‐optimization models.
Instant transportation solutions
Authors: Szwarc Wlodzimierz
Published: May 2007

This paper presents direct noniterative methods for solving such known problems as shoploading and aggregate scheduling. There is given a simple optimal rule for the shop‐loading problem which is quite surprising. The crucial point in solving this problem is what not to assign rather than what to assign. The development of those methods was possible since the discussed problems can be converted into a special transportation model where the given cost coefficients cij assume a form cij = ui + uj.
A dynamic, nonstationary inventory problem for a price/quantity setting firm
Authors: Thowsen Gunnar T.
Published: May 2007

A dynamic and nonstationary model is formulated for a firm which attempts to minimize total expected costs over a finite planning horizon. The control variables are price and production. The price p and the demand ζ are linked through the relationship ζ = g(p) + η, where g(p) is the riskless demand curve and η is a random variable. The general model allows for proportional ordering costs, convex holding and stockout costs, downward sloping riskless demand curve, backlogging, partial backlogging, lost sales, partial spoilage of inventory, and two modes of collecting revenue. Sufficient conditions are developed for this problem to have an optimal policy which resembles the single critical number policy known from stochastic inventory theory. It is also shown what set of parameters will satisfy these sufficiency conditions.
A special case of the 3 × n flow shop problem
Authors: Burns Fennell , Rooker John
Published: May 2007

Johnson [2] in 1954 solved the two machine flow shop problem by giving an argument for a sufficient condition of optimality and by stating an efficient algorithm which produces a solution via satisfaction of the sufficient condition. Moreover, Johnson solved two special cases of the corresponding three machine flow shop problem. Since that time, six other special cases have been solved, two contributed by Arthanari and Mukhopadhyay [1], two by Smith, Panwalkar, and Dudek [3], and two of a different nature by Szwarc [5]. This paper contributes an extension to one of the classes described by Szwarc.
Allocation of resources to offensive strategic weapon systems
Authors: Shere Kenneth D. , Wingate John W.
Published: May 2007

In this paper a very versatile game model is developed for use in the long range planning of our strategic force posture. This highly aggregate model yields optimal force mixes for the triad (land‐ and sea‐based missile systems and bombers) under a variety of constraints. The model described here is a survivability model; however, it is shown how the model can still be used as a measure of overall system effectiveness. Constraints imposed on the problem include both SALT and budget limitations.
Selection of the optimal setup policy
Authors: Ladany Shaul P. , Bedi Dina N.
Published: May 2007

A model is developed taking into consideration all the costs (namely cost of sampling, cost of not detecting a change in the process, cost of a false indication of change, and the cost of readjusting detected changes) incurred when a production process, using an unscheduled setup policy, utilizes fraction‐defective control charts to control current production. The model is based on the concept of the expected time between detection of changes calling for setups. It is shown that the combination of unscheduled setups and control charts can be utilized in an optimal way if those combinations of sample size, sampling interval, and extent of control limits from process average are used that provide the minimum expected total cost per unit of time.

The costs of a production process that uses unscheduled setups in conjunction with the appropriate optimal control charts are compared to the costs of a production process that uses scheduled setups at optimum intervals in conjunction with its appropriate control charts.

This comparison indicates the criteria for selecting production processes with scheduled setups using optimal setup intervals over unscheduled setups. Suggestions are made to evaluate the optimal process setup strategy and the accompanying optimal decision parameters, for any specific cost data, by use of computer enumeration. A numerical example for assumed cost and process data is provided.
The bilinear programming problem
Authors: Vaish Harish , Shetty C. M.
Published: May 2007

The paper deals with bilinear programming problems and develops a finite algorithm using the “piecewise strategy” for large‐scale systems. It consists of systematically generating a sequence of expanding polytopes with the global optimum within each polytope being known. The procedure then stops when the final polytope contains the feasible region.
MARKOVIAN DETERIORATION WITH UNCERTAIN INFORMATION — A MORE GENERAL MODEL
Authors: Rosenfield Donald
Published: May 2007

A model of a deteriorating system with imperfect information is considered. The structures appropriate for such a model include failing machinery and depleted inventory systems. In an effort to add a new dimension to such models, it is assumed that the operator must pay an inspection cost to determine the precise state of the system. At the start of every time period, the operator is faced with three choices: repair, no action, or inspection. Under fairly general assumptions, the optimal policy for repair is found to be straightforward and intuitive. This result has two important areas of application.
Flowshop sequencing problem with ordered processing time matrices: A general case
Authors: Smith M. L. , Panwalkar S. S. , Dudek R. A.
Published: May 2007

The ordered matrix flow shop problem with no passing of jobs is considered. In an earlier paper, the authors have considered a special case of the problem and have proposed a simple and efficient algorithm that finds a sequence with minimum makespan for a special problem. This paper considers a more general case. This technique is shown to be considerably more efficient than are existing methods for the conventional flow shop problems.
Mean square invariant forecasters for the weibull distribution
Authors: Tiago Oliveira J. De , Littauer Sebastian B.
Published: May 2007

Many techniques of forecasting are based upon extrapolation from time series. While such techniques have useful applications, they entail strong assumptions which are not explicitly enunciated. Furthermore, the time series approach not based on an indigenous forecast principle. The first attack from the present point of view was initiated by S. S. Wilks.

Of particular interest over a wide range of operational situations in reliability, for example, is the behavior of the extremes of the Weibull and Gumbel distributions. Here we formulate forecasters for the minima of various forms of these distributions. The forecasters are determined for minimization in mean square of the distance. From n original observations the forecaster provides the minimum of the next m observations when the original distribution is maintained.

For each of the forecasters developed, tables of efficiency have been calculated and included in the appendix. An explicit example has been included for one of the forecasters. Its performance has been demonstrated by the use of Monte Carlo technique. The results indicate that the forecaster can be used in practice with satisfactory results.
A comparison of several attribute sampling plans
Authors: Gelfand Alan E.
Published: May 2007

The purpose of this research is to examine several types of procedures for attribute sampling inspection‐the widely used Military Standard 105D plans [8], the lesser known Double Zero plans as developed by Ellis [4] and the Narrow Limit gaging plans of Ott and Mundel [9]. Each of the procedures is described with an effort made to illuminate their more subtle features. Then the plans are compared, whence it is revealed that (i) Narrow Limit gaging plans have a serious weakness in comparison to the others and (ii) Double Zero plans tend to be essentially conservative, but that sufficiently tight Military Standard 105D plans can be selected to achieve comparable performance in all ways.
Inequalities for mixed integer programs with structure
Authors: Glover Fred , Sommer David
Published: May 2007

Mixed integer programming problems arising in practice often contain special structures such as imbedded networks and multiple choice constraints. Easily derived inequalities are given that can be used to reduce the range of admissible solutions for such problems.
(R.Q) inventory problem with unknown mean demand and learning
Authors: Kaplan Alan J.
Published: May 2007

We address a single product, continuous review model with stationary Poisson demand. Such a model has been effectively studied when mean demand is known. However, we are concerned with managing new items for which only a Bayesian prior distribution on the mean is available. As demand occurs, the prior is updated and our control parameters are revised. These include the reorder point (R) and reorder quantity (Q).

Deemer, taking a clue from some earlier RAND work, suggested using a model appropriate for known mean, but using a Compound Poisson distribution for demand rather than Poisson to reflect uncertainty about the mean. Brown and Rogers also used this approach but within a periodic review context.

In this paper we show how to compute optimum reorder points for a special problem closely related to the problem of real interest. In terms of the real problem, subject to a qualification to be discussed, the reorder points found are upper bounds for the optimum. At the same time, the reorder points found can never exceed those found by the Compound Poisson (Deemer) approach. And they can be smaller than those found when there is no uncertainty about the mean.

As a check, the Compound Poisson and proposed approach are compared by simulation.
A cutting plane algorithm for the bilinear programming problem
Authors: Vaish H. , Shetty C. M.
Published: May 2007

In this paper we discuss the properties of a Bilinear Programming problem, and develop a convergent cutting plane algorithm. The cuts involve only a subset of the variables and preserve the special structure of the constraints involving the remaining variables. The cuts are deeper than other similar cuts.
Joint pricing and ordering policy for exponentially decaying inventory with known demand
Authors: Cohen Morris A.
Published: May 2007

This paper is concerned with the problem of simultaneously setting price and production levels for an exponentially decaying product. Such products suffer a loss in utility which is proportional to the total quantity of stock on hand. A continuous review, deterministic demand model is considered. The optimal ordering decision quantity is derived and its sensitivity to changes in perishability and product price is considered. The joint ordering pricing decision is also computed and consideration of parametric changes of these decisions indicates a non‐monotonic response for optimal price to changes in product decay. Issues of market entry and extensions to a model with shortages are also analyzed.
Probabilistic ideas in heuristic algorithms for solving some scheduling problems
Authors: Gertsbach I.
Published: May 2007

Heuristic algorithms for positioning a maximal number of independent units and constructing a schedule with minimal fleet size are proposed. These algorithms consist of two stages: defining the “leading” job and finding an optimal position for it. Decisions on both stages use some special criteria which have a probabilistic interpretation. Some experimental data are given.
Compound distributions with efficient computation in inventory model applications
Authors: Bott Donald L.
Published: May 2007

In an inventory model, the distribution of total units demanded can be considered as a compound distribution arising from the distributions of demand occurrence and individual demand size. Three such compound distributions are considered, where the number of demands is Poisson distributed. The demand size distribution will depend on the observed or desired variance‐to‐mean ratio. An approximation using the gamma distribution is given in terms of the cumulants of the compound distribution for both fixed and stochastic lead times.
A nonconvex max‐min problem
Authors: Falk James E. , Hoffman Karla
Published: May 2007

An algorithm designed to solve a large class of nonconvex max‐min problems is described. Its usefulness and applicability is demonstrated by solving an extension of a recently introduced model which optimally allocates strategic weapon systems. The extended model is shown to be equivalent to a nonconvex mathematical program with an infinite number of constraints, and hence is not solvable by conventional procedures. An example is worked out in detail to illustrate the algorithm.
Single server queues with hyperexponential service times
Authors: Greenberg Irwin
Published: May 2007

Single server queues with hyperexponential service times are studied. Explicit expressions are derived for the waiting time and state distributions.
Special cases of the flow‐shop problem
Authors: Szwarc Wlodzimierz
Published: May 2007

The paper examines all known special cases of the mXn flow‐shop problem. It provides solution procedures to three new special cases along with the optimality proofs. The theory of the new special cases is based on the critical path concept.
A model for the determination of optimal interfiring times
Authors: Friedman Yoram
Published: May 2007

Various models of stochastic duels with round dependent hit probabilities have appeared in the literature [1]. However, none of them analyzed the effect interfiring times will have on the hit probability.

In this paper we formulate a model for a marksman versus a passive target where the probability of a hit at a given round is a function of the interfiring times.

We show how to solve for the optimal interfiring times and prove that under certain assumptions the optimal rate of fire is a non‐decreasing function of the round fired.
A continuous review inventory model with compound poisson demand process and stochastic lead time
Authors: Dirickx Yvo M. I. , Koevoets Danielle
Published: May 2007

Using Markov renewal theory, we derive analytic expressions for the expected average cost associated with (s, S) policies for a continuous review inventory model with a compound Poisson demand process and stochastic lead time, under the (restrictive) assumption that only one order can be outstanding.
Computation of constrained optimum quantities and reorder points for time‐weighted backorder penalties
Authors: Matthews John P.
Published: May 2007

The purpose of this paper and the accompanying tables is to facilitate the calculation of constrained optimum order quantities and reorder points for an inventory control system where the criterion of optimality is the minimization of expected inventory holding, ordering, and time‐weighted backorder costs. The tables provided in the paper allow the identification of the optimal solution when order quantities and/or reorder points are restricted to a set of values which do not include the unconstrained optimal solution.
Numerical investigations on quadratic assignment problems
Authors: Burkard Rainer E. , Stratmann Karl‐Heinz
Published: May 2007

This paper contains a comparative study of the numerical behavior of different algorithms for solving quadratic assignment problems. After the formulation of the problem, branch and bound algorithms are briefly discussed. Then, starting procedures are described and compared by means of numerical results. Modifications of branch and bound procedures for obtaining good suboptimal solutions are treated in the next section. Subsequently, numerical results with the Gaschütz‐Ahrens algorithm are reported. In the last section, exchange algorithms are discussed, and it is pointed out how they can be combined efficiently with the Gaschütz‐Ahrens procedure and the perturbation method. All suboptimal solutions found in the literature could be improved by these combined methods. In the appendix, test examples and the best known solutions are listed.
Novel corrective equations for complete estimation of human tissue lipids after their partial destruction by perchloric acid pre‐treatment: high‐resolution 1H‐NMR‐based study
Authors: Srivastava Niraj Kumar , Pradhan Sunil , Mittal Balraj , Kumar Raj , Pandey Chandra Mani , Gowda G. A. Nagana
Published: May 2007

Owing to the small quantity of tissue available in human biopsy specimens, aqueous and lipid components often have to be determined in the same tissue sample. Perchloric acid (PCA) used for the extraction of aqueous metabolites has a deleterious effect on lipid components; the severity of the damage is not known. In this study, human muscle tissue was first treated with PCA to extract aqueous metabolites, and the residue was then used for lipid extraction by conventional methods, i.e. the methods of Folch and Bligh & Dyer and a standardised one using methanol/chloroform (1:3, v/v) used in our laboratory. A 1H‐NMR spectrum was obtained for each lipid extract. Lipid was quantified by measuring the integral area of N+‐(CH3)3 signals of phospholipids (PLs). Triacylglycerol (TG) and cholesterol (CHOL) were quantified using the ‐CH2‐ signals of glycerol and the C18 methyl signal, respectively. This study shows that prior use of PCA caused marked attenuation of TG, PL, and CHOL. This was confirmed by recovery experiments and observation of the direct effect of PCA on the standard lipid components. On the basis of the quantity of lipid lost in each case, three novel equations (with respect to TG, PL, and CHOL) were derived. Application of these equations to lipid quantities estimated in different pathological tissues after PCA pre‐treatment produced values equivalent to those estimated without PCA use. This study conclusively shows that PCA pre‐treatment damages all three lipid moieties, TG, PL, and CHOL. When PCA is used in a fixed ratio to the tissue, the lipid damage is also proportional and correctable by statistically derived equations. These equations will be useful in human biopsy specimens where aqueous and lipid components have to be studied using the same tissue sample because of the small quantity available. Copyright © 2007 John Wiley & Sons, Ltd.
The angiogenic factor thymidine phosphorylase up‐regulates the cell adhesion molecule P‐selectin in human vascular endothelial cells and is associated with P‐selectin expression in breast cancers
Authors: Gunningham SP , Currie MJ , Morrin HR , Tan EY , Turley H , Dachs GU , Watson AI , Frampton C , Robinson BA , Fox SB
Published: May 2007

Thymidine phosphorylase (TP) is an angiogenic enzyme, catalysing the reversible phosphorylation of thymidine to thymine and 2‐deoxyribose. TP is up‐regulated in neoplasia, being associated with advanced tumour stage, microvessel density and prognosis in several tumour types. Although TP is a non‐mitogenic migratory factor for endothelium, the mechanism by which TP mediates these effects is still unclear. We compared the gene expression profile of endothelial cells grown in vitro in the presence or absence of TP by cDNA microarray analysis. To determine the time‐course of TP angiogenic induction, endothelial cells were stimulated with TP (10 ng/ml) for 5 and 18 h. Gene expression levels of Tie2, angiopoietin (Ang)1 and Ang2, measured by RNase protection assay (RPA), showed maximal alteration at 18 h. cDNA from human umbilical vein endothelial cells (HUVEC) grown for 18 h in the presence or absence of TP (10 ng/ml) was hybridized to a human cDNA cytokine array representing 375 angiogenic genes. Significantly altered expression occurred in 89 human angiogenic genes (72 genes were up‐regulated and 17 down‐regulated). Changes in five genes relevant to vascular remodelling biology (Tie2, nNos, P‐selectin, ephrin‐B1 and TP) were validated in triplicate experiments by real‐time RT–PCR. But only P‐selectin gene expression remained significant. Correlation between P‐selectin and TP was assessed by immunohistochemistry on 161 human breast cancers, using human tissue microarray. Tumour cell TP correlated with tumour cell P‐selectin but not with endothelial cell P‐selectin. These data show that TP stimulates changes in mRNA expression maximally after 18 h culture in vitro. It confirms a role for TP in vascular remodelling involving several classes of genes, including the cell adhesion molecule, P‐selectin. Although confirmation of the role of TP‐mediated cell adhesion molecule (CAM) induction is required; however, this pathway may provide an attractive therapeutic target, since it is likely to affect several important tumour processes, including angiogenesis and metastasis. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Bisphenol containing novel polyimides/glass fiber composites
Authors: Bhuvana S. , Saroja Devi M.
Published: May 2007

A new diamine was synthesized using bisphenol‐A and p‐amino benzoic acid. Polyimides I and II were prepared with the diamine and pyromellitic dianhydride/3,3′,4,4′ benzophenone tetracarboxylic acid dianhydride. Bismaleimide (BMI) was synthesized using the same diamine and maleic anhydride. The prepared diamine and polyimides were characterized using FTIR. Thermo gravimetric analysis was used to study the thermal properties of synthesized polyimides and BMI. Woven glass fabric/unidirectional glass fiber‐polyimide/BMI composites were made and their properties (fiber volume fraction, density, tensile, flexural, impact, and hardness) were studied and compared with a few representative carbon fiber polyimide, carbon fiber–epoxy, and glass fiber–epoxy composites. The prepared composites were subjected to thermal aging and moisture absorption and their effects on tensile and flexural properties were studied. POLYM. COMPOS., 28: 372–380, 2007. © 2007 Society of Plastics Engineers
Elastic response of nanocomposite poly(vinylacetate)‐hydroxyapatite with varying particle shape
Authors: Kalfus J. , Jancar J.
Published: May 2007

The mechanisms by which hydroxyapatite nanofiller promotes reinforcement in poly(vinylacetate) matrix is investigated. Hydroxyapatite nanofillers with spherical and platelet particle shape were synthesized. Particle size was in the range from 5 to 60 nm. Filler concentration in composites was limited to maximum of 5 vol% to minimize filler networking. Effect of the nanofiller particle shape on the elastic response of nanocomposite was examined using dynamic‐mechanical thermal spectroscopy. Attempt to interpret the observed phenomena was based on the molecular approach. POLYM. COMPOS., 28: 365–371, 2007. © 2007 Society of Plastics Engineers
Energetic and structural characterization of 2‐R‐3‐methylquinoxaline‐1,4‐dioxides (R = benzoyl or tert‐butoxycarbonyl): experimental and computational studies
Authors: Gomes José R. B. , Sousa Emanuel A. , Gonçalves Jorge M. , Gales Luís , Damas Ana M. , Gomes Paula , Pandey Siddharth , Acree William E. , da Silva Maria D. M. C. Ribeiro
Published: May 2007

The gaseous standard molar enthalpies of formation of two 2‐R‐3‐methylquinoxaline‐1,4‐dioxides (R = benzoyl or tert‐butoxycarbonyl), at T = 298.15 K, were derived using the values for the enthalpies of formation of the compounds in the condensed phase, measured by static bomb combustion calorimetry, and for the enthalpies of sublimation, measured by Knudsen effusion, using a quartz crystal oscillator. The three dimensional structure of 2‐tert‐butoxycarbonyl‐3‐methylquinoxaline‐1,4‐dioxide has been obtained by X‐ray crystallography showing that the two NO bond lengths in this compound are identical. The experimentally determined geometry in the crystal is similar to that obtained in the gas‐phase after computations performed at the B3LYP/6‐311 + G(2d,2p) level of theory. The experimental and computational results reported allow to extend the discussion about the influence of the molecular structure on the dissociation enthalpy of the NO bonds for quinoxaline 1,4‐dioxide derivatives. As found previously, similar NO bond lengths in quinoxaline‐1,4‐dioxide compounds are not linked with NO bonds having the same strength. Copyright © 2007 John Wiley & Sons, Ltd.
Effect of substitution of oxygen by sulfur in the nonleaving group of a carbonate: kinetics of the phenolysis and benzenethiolysis of S‐methyl aryl thiocarbonates
Authors: Castro Enrique A. , Aliaga Margarita , Santos José G.
Published: May 2007

The phenolysis and benzenethiolysis of S‐methyl 4‐nitrophenyl thiocarbonate (1) and S‐methyl 2,4‐dinitrophenyl thiocarbonate (2) in water are studied kinetically. The Brønsted plots (log k
N versus nucleophile basicity) are linear for all reactions. The Brønsted slopes for 1 and 2 are, 0.51 and 0.66 (phenolysis) and 0.55 and 0.70 (benzenethiolysis), respectively. These values suggest a concerted mechanism for these reactions, as found in the corresponding carbonates. Namely, substitution of OMe by SMe in the nonleaving group does not change the mechanism. Copyright © 2007 John Wiley & Sons, Ltd.
Minimum electrophilicity principle in photocycloaddition formation of oxetanes
Authors: Noorizadeh S.
Published: May 2007

The regio‐ and stereoselectivity of some Paternó–Büchi reactions are studied within a density functional framework with B3LYP exchange‐correlation energy functional and 6‐31G** basis set. It is shown that although in most cases the Minimum Polarizability and the Maximum Hardness Principles (MPP and MHP) successfully predict the major oxetane products of these reactions, but in all of the considered reactions, with no exception, the main products have the lesser electrophilicity values than the minor isomers, and therefore the Minimum Electrophilicity Principle (MEP) correctly predicts the most stable stereoisomer of the reaction. Copyright © 2007 John Wiley & Sons, Ltd.