bluuebunny/crossref_metadata_2025_split huggingface dataset:
The cyclic separation scheduling problem
Authors: Armstrong Ronald D. , Sinha Prabhakant 
Published: May 2007

AbstractThis paper deals with the problem of scheduling items (tasks, employees, equipment, etc.) over a finite time horizon so as to minimize total cost expenditures while maintaining a predefined separation between certain items. The problem is cyclic, because the same schedule will be repeated over several consecutive time periods of equal length. Thus, requirements are present to maintain the separation of items not only within the individual time periods considered, but also between items in adjoining periods. A special purpose branch‐and‐bound algorithm is developed to solve this scheduling problem by taking advantage of its cyclic nature. Computational results are given.
A primal simplex algorithm to solve a rectilinear distance facility location problem
Authors: Armstrong Ronald D. 
Published: May 2007

AbstractThis paper considers the problem of locating m new facilities in the plane so as to minimize a weighted rectangular distance between the new facilities and n existing facilities. A special purpose primal simplex algorithm is developed to solve this problem. The algorithm will maintain at all times a basis of dimension m by m; however, because of the triangularity of the basis matrix, it will not be necessary to form a basis inverse explicitly.
An analytical minefield evaluation model without space averages
Authors: Mjelde K. M. 
Published: May 2007

AbstractThe paper describes an approach to the evaluation of the effectiveness of a minefield in terms of the number of mines that are detonated by a convoy of sweepers and ships and the corresponding number of vessels that are immobilized. The positions of the mines and the tracks of the vessels are assumed to be known, which means that the evaluation measures are dependent on a large number of disjoint events, each event being the immobilization of particular vessels by particular mines. This may render combinatorial methods computationally infeasible, but by introducing approximations in the assumptions, the difficulty can be overcome, specifically by modelling the arrival of each individual vessel in the neighborhood of a mine by an inhomogeneous Poisson stream for which the arrival rate is nonzero only over a short time interval. The plausibility of the approach is supported by results of a critical‐event simulation model.
A procedure for generating time‐dependent arrivals for queueing simulations
Authors: Fishman George S. , Kao Edward P. C. 
Published: May 2007

AbstractThis paper presents a method for modeling cyclic inputs to a congested system in a discrete event digital simulation. Specifically, we express the mean of the interarrival time conditional on the last arrival as a linear combination of harmonic components whose coefficients can be determined by stepwise regression. We also assume that the conditional interarrival time normalized by its corresponding mean follows a distribution that is independent of time. The result can, in turn, be used to generate the desired input for a simulation, An example based on a set of actual data is used to illustrate the process of parameter estimation for the model.
Estimating reliability growth (or deterioration) using time series analysis
Authors: Singpurwalla Nozer D. 
Published: May 2007

AbstractIn this paper we propose a method for estimating reliability growth (or deterioration) using time series analysis. Our method does not call for the specification of a particular model, and estimates the growth in the presence of periodicity. We illustrate our procedure by considering some binomial failure data generated during the testing of a large system of the U.S. Navy.
General trigger‐off replacement procedures for two‐unit systems
Authors: Berg Menachem 
Published: May 2007

AbstractA trigger‐off replacement policy, suggested and analyzed in [1], for two‐unit systems composed of identical units, is generalized and extended in this work in several ways. In the first part of the paper we obtain the appropriate integral equations for nonidentical units and then use them for a complete solution of the case of two units, whose lifetimes are distributed according to general Erlang distributions. In the second part of the paper we extend the trigger‐off policy itself by allowing preventive replacements of units which reach a certain critical age. The system stops working if either one of the two units fails or reaches its critical age. Both cases present natural replacement possibilities for the remaining unit, provided that its age exceeds a predetermined critical age.Finally, we consider the question of which policy parameters, i.e. control limits and critical ages, to choose when facing a real‐life situation. Using the criterion of expected costs per unit time in the long run, we show how to find the optimal parameters which minimize this objective function. The fact that a restricted optimization, within the class of trigger‐off replacement policies, leads to the global optimal policy has been proved in [2] by a different approach.
A linear programming approach to geometric programs
Authors: Dinkel John J. , Kochenberger Gary A. , Elliott William H. 
Published: May 2007

AbstractA cutting plane method, based on a geometric inequality, is described as a means of solving geometric programs. While the method is applied to the primal geometric program, it is shown to retain the geometric programming duality relationships. Several methods of generating the cutting planes are discussed and illustrated on some example problems.
Nonstationary stochastic gold‐mining: A time‐sequential tactical‐allocation problem
Authors: Hall Gaineford J. 
Published: May 2007

AbstractThis paper presents an extension of gold‐mining problems formulated in earlier work by R. Bellman and J. Kadane. Bellman assumes there are two gold mines labeled A and B, respectively, each with a known initial amount of gold. There is one delicate gold‐mining machine which can be used to excavate one mine per day. Associated with mine A is a known constant return rate and a known constant probability of breakdown. There is also a return rate and probability of breakdown for mine B. Bellman solves the problem of finding a sequential decision procedure to maximize the expected amount of gold obtained before breakdown of the machine. Kadane extends the problem by assuming that there are several mines and that there are sequences of constants such that the jth constant for each mine represents the return rate for the jth excavation of that mine. He also assumes that the probability of breakdown during the jth excavation of a mine depends on j. We extend these results by assuming that the return rates are random variables with known joint distribution and by allowing the probability of breakdown to be a function of previous observations on the return rates. We show that under certain regularity conditions on the joint distributions of the random variables, the optimal policy is: at each stage always select a mine which has maximal conditional expected return per unit risk. This gold‐mining problem is also a formulation of the problem of time‐sequential tactical allocation of bombers to targets. Several examples illustrating these results are presented.
The queue G/M/m/N: Busy period and cycle, waiting time under reverse and random order service
Authors: Rosenlund Stig I. 
Published: May 2007

AbstractThe busy period, busy cycle, and the numbers of customers served and lost therein, of the G/M/m queue with balking is studied via the embedded Markov chain approach. It is shown that the expectations of the two discrete variables give the loss probability. For the special case G/M/1/N a closed expression in terms of contour integrals is obtained for the Laplace transform of these four variables. This yields as a byproduct the LIFO waiting time distribution for the G/M/m/N queue. The waiting time under random order service for this queue is also studied.
Steady state waiting time in a multicenter job shop
Authors: Kapadia Asha S. , Hsi Bartholomew P. 
Published: May 2007

AbstractThis paper analyzes the waiting‐time distribution of a specific job as it moves through a job‐shop with multiple centers and exponential service times. The movement of the job through the shop is governed by a Markovian transition matrix and ends with the job's exit from the shop.
An examination of the effects of the criterion functional on optimal fire‐support policies
Authors: Taylor James G. , Brown Gerald G. 
Published: May 2007

AbstractThis paper examines the dependence of the structure of optimal time‐sequential fire‐support policies on the quantification of military objectives by considering four specific problems, each corresponding to a different quantification of objectives (i.e. criterion functional). We consider the optimal time‐sequential allocation of supporting fires during the “approach to contact” of friendly infantry against enemy defensive positions. The combat dynamics are modelled by deterministic Lanchester‐type equations of warfare, and the optimal fire‐support policy for each one‐sided combat optimization problem is developed via optimal control theory. The problems are all nonconvex, and local optima are a particular difficulty in one of them. For the same combat dynamics, the splitting of supporting fires between two enemy forces in any optimal policy (i.e. the optimality of singular subarcs) is shown to depend only on whether the terminal payoff reflects the objective of attaining an “overall” military advantage or a “local” one. Additionally, switching times for changes in the ranking of target priorities are shown to be different (sometimes significantly) when the decision criterion is the difference and the ratio of the military worths (computed according to linear utilities) of total infantry survivors and also the difference and the ratio of the military worths (computed according to linear utilities) of total infantry survivors and also the difference and the ratio of the military worths of the combatants' total infantry losses. Thus, the optimal fire‐support policy for this attack scenario is shown to be significantly influenced by the quantification of military objectives.
An algorithm for a class of loading problems
Authors: Hung Ming S. , Brown J. Randall 
Published: May 2007

AbstractThe loading problem we consinder is to assign a set of discrete objects, each having a weight, to a set of boxes, each of which has a capacity limit, in such a way that every object is assigned to a box and the number of boxes used is minimized.A characterization of the assignments is offered and used to develop a set of rules for generating nonredundant assignments. The rules are incorporated into an implicit enumeration algorithm. The algorithm is tested against a very good heuristic. Computational experience shows that the algorithm is highly efficient, solving problems of up to 3600 0‐1 variables in a CPU second.
Pseudo‐monotonic interval programming
Authors: Bector C. R. , Bhatt S. K. 
Published: May 2007

AbstractA pseudo‐monotonic interval program is a problem of maximizing f(x) subject to x ε X = {x ε Rn | a < Ax < b, a, b ε Rm} where f is a pseudomonotonic function on X, the set defined by the linear interval constraints. In this paper, an algorithm to solve the above program is proposed. The algorithm is based on solving a finite number of linear interval programs whose solutions techniques are well known. These optimal solutions then yield an optimal solution of the proposed pseudo‐monotonic interval program.
Differential‐game examination of optimal time‐sequential fire‐support strategies
Authors: Taylor James G. 
Published: May 2007

AbstractOptimal time‐sequential fire‐support strategies are studied through a two‐person zero‐sum deterministic differential game with closed‐loop (or feedback) strategies. Lanchester‐type equations of warfare are used in this work. In addition to the max‐min principle, the theory of singular extremals is required to solve this prescribed‐duration combat problem. The combat is between two heterogeneous forces, each composed of infantry and a supporting weapon system (artillery). In contrast to previous work reported in the literature, the attrition structure of the problem at hand leads to force‐level‐dependent optimal fire‐support strategies with the attacker's optimal fire‐support strategy requiring him to sometimes split his artillery fire between enemy infantry and artillery (counterbattery fire). A solution phenomnon not previously encountered in Lanchester‐type differential games is that the adjoint variables may be discontinuous across a manifold of discontinuity for both players' strategies. This makes the synthesis of optimal strategies particularly difficult. Numerical examples are given.
Some approximations in multi‐item, multi‐echelon inventory systems for recoverable items
Authors: Muckstadt John A. 
Published: May 2007

AbstractThe optimization problem as formulated in the METRIC model takes the form of minimizing the expected number of total system backorders in a two‐echelon inventory system subject to a budget constraint. The system contains recoverable items – items subject to repair when they fail. To solve this problem, one needs to find the optimal Lagrangian multiplier associated with the given budget constraint.For any large‐scale inventory system, this task is computationally not trivial. Fox and Landi proposed one method that was a significant improvement over the original METRIC algorithm. In this report we first develop a method for estimating the value of the optimal Lagrangian multiplier used in the Fox‐Landi algorithm, present alternative ways for determining stock levels, and compare these proposed approaches with the Fox‐Landi algorithm, using two hypothetical inventory systems – one having 3 bases and 75 items, the other 5 bases and 125 items. The comparison shows that the computational time can be reduced by nearly 50 percent.Another factor that contributes to the higher requirement for computational time in obtaining the solution to two‐echelon inventory systems is that it has to allocate stock optimally to the depot as well as to bases for a given total‐system stock level. This essentially requires the evaluation of every possible combination of depot and base stock levels – a time‐consuming process for many practical inventory problems with a sizable system stock level. This report also suggests a simple approximation method for estimating the optimal depot stock level. When this method was applied to the same two hypotetical inventory systems indicated above, it was found that the estimate of optimal depot stock is quite close to the optimal value in all cases. Furthermore, the increase in expected system backorders using the estimated depot stock levels rather than the optimal levels is generally small.
An inventory depletion problem with random and age‐dependent lifetimes
Authors: Thorburn Daniel 
Published: May 2007

AbstractThe following problem is studied. The units of an inventory are used one by one until all have failed. Their lifetimes decrease with their ages, when they are taken out of the inventory. An item of age a is supposed to have a lifetime Y exp(‐a), where Y is a random variable which does not depend on a. It is shown that in order to maximize the total lifetime the items should be taken according to the LIFO principle. This is shown for a certain class of distributions of Y. This class includes the exponential and the Pareto distributions.
All‐integer linear programming — a new approach via dynamic programming
Authors: Cooper Leon , Cooper Mary W. 
Published: May 2007

AbstractAn exact method for solving all‐integer linear‐programming problems is presented. Dynamic‐programming methodology is used to search efficiently candidate hyperplanes for the optimal feasible integer solution. The explosive storage requirements for high‐dimensional dynamic programming are avoided by the development of an analytic representation of the optimal allocation at each stage. Computational results for problems of small to moderate size are also presented.
Maximizing the sum of certain quasiconcave functions using generalized benders decomposition
Authors: Cabot A. Victor 
Published: May 2007

AbstractIn this paper we consider the problem of maximizing the sum of certain quasi‐concave functions over a convex set. The functions considered belong to the classes of functions which are known as nonlinear fractional and binonlinear functions. Each individual function is quasi‐concave but the sum is not. We show that this nonconvex programming problem can be solved using Generalized Benders Decomposition as developed by Geoffrion.
High b‐value q‐space diffusion MRS of nerves: structural information and comparison with histological evidence
Authors: Bar‐Shir Amnon , Cohen Yoram 
Published: May 2007

AbstractHigh b‐value q‐space diffusion MRS was used to study the diffusion characteristics of formalin‐fixed swine optic and sciatic nerves over a large range of diffusion times (3.7–99.3 ms). The very short diffusion time range was studied with a 1 ms resolution. The displacement distribution profiles obtained were fitted to a bi‐Gaussian function, and structural parameters were extracted from the q‐space diffusion MRS data. This structural information was correlated with axon sizes obtained by histological examination. It was found that high b‐value q‐space diffusion MRS can easily distinguish between the two nerve types. The root mean square displacements (rmsds) of both the slow and fast diffusing components of the optic nerves were found to be smaller than those of the sciatic nerves. When the rmsd was plotted against the square root of the diffusion time (t), it was found that all four components showed an increase in rmsd; this increase was significantly smaller than expected from the Einstein equation. However, the most restricted component is the slow diffusing component of the optic nerve. This is also the only diffusing component that shows a large change in the slope (i.e. a ‘breaking point’) of the plot of rmsd as a function of t. This rmsd is very similar to the mean axon size of these optic nerves determined histologically. Such a change in slope was less apparent for the slow diffusing component of sciatic nerves, which showed a wider distribution of axon size in histological images. The fast diffusing components of both nerve types showed only a small gradual change in the slope of rmsd plotted against t. These findings are discussed in the context of component assignment, origin of restriction, and relationships between the structural information extracted from q‐space diffusion MRS and histological examination. Copyright © 2007 John Wiley & Sons, Ltd.
Structure–property relationships in glass reinforced polyamide, part 2: The effects of average fiber diameter and diameter distribution
Authors: Thomason J. L. 
Published: May 2007

AbstractWe present the results of an extensive study of the influence of average fiber diameter and the width of the diameter distribution on the performance of injection‐molded glass‐fiber reinforced polyamide 6,6. In the average fiber diameter range from 9 to 18 μm, dry‐as‐molded (DaM) composite unnotched impact and tensile strength decreased significantly. The composite notched impact performance and tensile modulus showed little dependence on fiber diameter. The influence of broadening the fiber diameter distribution by blending glass fiber samples of different average diameter was found to be particularly negative on the level of composite unnotched impact when compared at equal number average diameter. After hydrolysis treatment, the composite tensile strength and modulus exhibited a large drop compared to the DaM results. In contrast, the unnotched impact results became insensitive to fiber diameter after hydrolysis. The average level of unnotched impact after hydrolysis was sufficiently high to show an increase over DaM when the fiber diameter was above 14 μm. Residual fiber length correlated significantly with fiber diameter with a lower average length for thinner fibers. The interfacial shear strength was found to be in the range of 26–34 MPa for DaM composites. There was a highly significant inverse correlation between the DaM interfacial strength and the average fiber diameter. It is shown that results from both tensile and unnotched impact measurements can be brought back to single trend lines by using a Z average value for the average fiber diameter, which is more heavily weighted to the thicker fibers in the distribution. POLYM. COMPOS., 28:331–343, 2007. © 2007 Society of Plastics Engineers
Measurement of low velocity and quasi‐static failure modes in PMMA
Authors: Pearson J.D. , Zikry M.A. , Prabhugoud M. , Peters K. 
Published: May 2007

AbstractAn investigation of the low velocity impact and quasi‐static failure of polymethylmethacrylate (PMMA) based on global and local strain measurements was conducted. Local strains were obtained from surface‐mounted fiber Bragg grating (FBG) sensors, and they were combined with global measurements from quasi‐static indentation and low‐velocity impact experiments to obtain detailed maps of how failure evolves. For both loading regimes, the interactions between the host PMMA specimens and the sensors played a crucial role in the evolution of residual strains. A mapping of the strains clearly shows that strains decrease radially, from high values near the point of impact to far‐field values. Sensors located in critical locations had the highest residual strains prior to PMMA fracture. Furthermore, it was determined that strain transfer to the sensor is strongly influenced by the bonding conditions at the specimen's surface. Because of the debonding of the sensor and the frictional effects associated with the bonding agent, compressive residual strains occurred on the rear‐surface. Hence, a detailed understanding of how strain evolves due to sensor–host interactions and catastrophic fracture can be obtained, which can potentially be used to mitigate damage in PMMA for a range of strain rates. POLYM. COMPOS., 28:381–391, 2007. © 2007 Society of Plastics Engineers
Role of cationic gemini surfactants toward enhanced ninhydrin–tryptophan reaction
Authors: Kabir‐ud‐Din  , Fatma Waseefa 
Published: May 2007

AbstractIn this paper we report the effect of dicationic ‘gemini’ surfactants (CH3)2C16H33N+ (CH2)mN+C16H33(CH3)2, 2Br−(wherem = 4, 5, 6) on the reaction of ninhydrin withDL‐tryptophan. The gemini surfactant micellar media are comparatively more effective than their conventional monomeric counterpart cetyltrimethylammonium bromide (CTAB) micelles. Also, whereas typical rate constant (kψ) increase and leveling‐off regions, just like CTAB, are observed with geminis, the latter produce a third region of increasingkψat higher concentrations. These subsequent increases are ascribed to changes in micellar morphologies, consistent with changes in1H NMR line widths. Quantitative kinetic analysis of the rate constant–[surfactant] data has been performed on the basis of modified pseudophase model. Copyright © 2007 John Wiley & Sons, Ltd.