bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal stocking policies for low usage items in multi‐echelon inventory systems
Authors: Cohen Morris A. , Kleindorfer Paul R. , Lee Hau Leung 
Published: May 2007

AbstractMulti‐echelon logistic systems are essential parts of the service support function of high technology firms. The combination of technological developments and competitive pressures has led to the development of services systems with a unique set of characteristics. These characteristics include (1) low demand probabilities: (2) high cost items; (3) complex echelon structures; (4) existence of pooling mechanisms among stocking locations at the same echelon level; (5) high priority for service, which is often expressed in terms of response time service levels for product groups of items: (6) scrapping of failed parts; and (7) recycling of issued stock due to diagnostic use. This article develops a comprehensive model of a stochastic, multi‐echelon inventory system that takes account of the above characteristics. Solutions to the constrained optimization problem are found using a branch and bound procedure. The results of applying this procedure to a spare parts inventory system for a computer manufacturer have led to a number of important policy conclusions.
A lagrangean relaxation algorithm for the constrained matrix problem
Authors: Cottle Richard W. , Duvall Steven G. , Zikan Karel 
Published: May 2007

AbstractWe present variants of a convergent Lagrangean relaxation algorithm for minimizing a strictly convex separable quadratic function over a transportation polytope. The algorithm alternately solves two “subproblems,” each of which has an objective function that is defined by using Lagrange multipliers derived from the other. Motivated by the natural separation of the subproblems into independent and very easily solved “subsubproblems,” the algorithm can be interpreted as the cyclic coordinate ascent method applied to the dual problem. We exhibit our computational results for different implementations of the algorithm applied to a set of large constrained matrix problems.
Minimizing mean absolute deviation of completion times about a common due date
Authors: Bagchi Uttarayan , Sullivan Robert S. , Chang Y. L. 
Published: May 2007

AbstractWe consider a single machine scheduling problem in which the objective is to minimize the mean absolute deviation of job completion times about a common due date. We present an algorithm for determining multiple optimal schedules under restrictive assumptions about the due date, and an implicit enumeration procedure when the assumptions do not hold. We also establish the similarity of this problem to the two parallel machines mean flow time problem.
Hybrid heuristics for minimum cardinality set covering problems
Authors: Vasko Francis J. , Wilson George R. 
Published: May 2007

AbstractMinimum cardinality set covering problems (MCSCP) tend to be more difficult to solve than weighted set covering problems because the cost or weight associated with each variable is the same. Since MCSCP is NP‐complete, large problem instances are commonly solved using some form of a greedy heuristic. In this paper hybrid algorithms are developed and tested against two common forms of the greedy heuristic. Although all the algorithms tested have the same worst case bounds provided by Ho [7], empirical results for 60 large randomly generated problems indicate that one algorithm performed better than the others.
End effects in capacity expansion models with finite horizons
Authors: Murphy F. H. , Soyster A. L. 
Published: May 2007

AbstractCapacity expansion models are typically formulated in the context of some finite horizon. Because the firm lasts longer than the horizon, a bias can enter into the optimal solution from the model horizon chosen. Recently, Grinold [8] has proposed a “dual‐equilibrium method” for ameliorating possible distortions. Although the dual‐equilibrium method has superior analytical properties to other methods, it is conceptually more complex. In this paper it is shown that there are situations where the “primal‐equilibrium” approach of Manne [15] provides equivalent results and that the use of annualized capital costs in the objective function, although somewhat less efficient, results in a similar model.
Computational aspects in multistage bayesian acceptance sampling
Authors: Waldmann K.‐H. 
Published: May 2007

AbstractSimple criteria are found for reducing the computational effort in multistage Bayesian acceptance sampling. Regions of optimality are given for both terminal actions accept and reject. Also, criteria are presented for detecting nonoptimality of sets of sample sizes. Finally, nearly optimal (z,c−,c+)‐sampling plans are constructed by restricting attention to a small subset of sample sizes.
Test for the extreme value and weibull distributions based on normalized spacings
Authors: Lockhart R. A. , O'Reilly F. , Stephens M. A. 
Published: May 2007

AbstractDiscussed in this article are tests for the extreme‐value distribution, or, equivalently, for the two‐parameter Weibull distribution when parameters are unknown and the sample may be censored. The three tests investigated are based on the median, the mean, and the Anderson‐DarlingA2statistic calculated from a setziof values derived from the spacings of the sample. The median and the mean have previously been discussed by Mann, Scheuer, and Fertig [10] and by Tiku and Singh [14]. Asymptotic distributions and points are given for the test statistics, based on recently developed theory, and power studies are conducted to compare them with each other and with two other statistics suitable for the test. Of the normalized spacings tests,A2is recommended overall; the mean also gives good power in many situations, but can be nonconsistent.
Geometric programming with multiplicative slack variables
Authors: McNamara John R. 
Published: May 2007

AbstractA posynomial geometric programming problem formulated so that the number of objective function terms is equal to the number of primal variables will have a zero degree of difficulty when augmented by multiplying each constraint term by a slack variable and including a surrogate constraint composed of the product of the slack variables, each raised to an undetermined negative exponent or surrogate multiplier. It is assumed that the original problem is canonical. The exponents in the constraint on the product of the slack variables must be estimated so that the associated solution to the augmented problem, obtained immediately, also solves the original problem. An iterative search procedure for finding the required exponents, thus solving the original problem, is described. The search procedure has proven quite efficient, often requiring only two or three iterations per degree of difficulty of the original problem. At each iteration the well‐known procedure for solving a geometric programming problem with a zero degree of difficulty is used and so computations are simple. The solution generated at each iteration is optimal for a problem which differs from the original problem only in the values of some of the constraint coefficients, so intermediate solutions provide useful information.
Location of regional facilities
Authors: Drezner Zvi 
Published: May 2007

AbstractIn this paper we consider the single‐facility and multifacility problems of the minisum type of locating facilities on the plane. Both demand locations and the facilities to be located are assumed to have circular shapes, and demand and service is assumed to have a uniform probability density inside each shape. The expected distance between two facilities is calculated. Euclidean and squared‐Euclidean distances are discussed.
Warranty design under buyer and seller risk aversion
Authors: Ritchken Peter H. , Tapiero Charles S. 
Published: May 2007

AbstractThis paper provides a framework in which warranty policies for non‐repairable items can be evaluated according to risk preferences of both buyers and sellers. In particular, a warranty price schedule is established such that sellers are indifferent among the policies. Given this schedule, a buyer's response is expressed by selecting the price‐warranty combination that minimizes disutility. Within this framework, a warranty can be viewed as an instrumet of risk management that can induce more sales and greater profitability. For given utility functions, analytical results for the development of a price schedule are developed. Numerical results illustrate the substitution effects between warranty terms, prices, and risk parameters.
Stochastic leadtimes in continuous‐time inventory models
Authors: Zipkin Paul 
Published: May 2007

AbstractThis paper shows that one of the fundamental results of inventory theory is valid under conditions much broader than those treated previously. The result characterizes the distributions of inventory level and inventory position in the standard, continuous‐time model with backorders, and leads to the relatively easy calculation of key performance measures. We treat both fixed and random leadtimes, and we examine both stationary and limiting distributions under different assumptions. We consider demand processes described by several general classes of compound‐counting processes and a variety of order policies. For the stochastic‐leadtime case we provide the first explicit proof of the result, assuming the leadtimes are generated according to a specific, but plausible, scenario.
Routing in computer networks
Authors: Frank H. , Chou W. 
Published: May 2007

AbstractThe problem of routing flow in a network of computers is extremely complex. This is especially formidable when routing is to be incorporated in iterative analysis and design. Among the properties of desirable flow patterns is low average delay from message inception to arrival. In this paper, we discuss procedures for minimizing average delay subject to a set of flow constraints. Heuristic routing procedures are presented and compared to optimum routing procedures. Computational experience is given.
Steiner's problem in graphs and its implications
Authors: Hakimi S. L. 
Published: May 2007

AbstractA graph theoretic version of Steiner's problem in plane geometry is described. An approach for solving this problem, related to Melzak's solution to Steiner's problem, is presented. The problems of finding “shortest route” and “minimal spanning tree” in graphs become special cases of the Steiner's problem in graphs. It is shown that a solution to this problem also provides us with a solution to the problems of finding a minimum externally stable set and a maximum internally stable set in a graph.
Minimum cost routing for static network models
Authors: Yaged B. 
Published: May 2007

AbstractThis paper develops techniques which can be applied to long range planning studies for the domestic long haul communications network. The problem studied is how to select a path through the network for each point‐to‐point demand for communications channels, so that the total network cost is minimized. The problem is to minimize total network cost, subject to multicommodity flow requirements and concave link cost functions. Finding an exact solution is difficult because of the concavity of the cost functions and the complexity (100 to 200 nodes and 200 to 300 links) of the network structure. A specialized technique is developed to provide locally optimal solutions to the problem, one of minimizing a concave function over a convex constraint set. When the link cost displays a fixed charge, a modification of the iterative algorithm provides acceptable a modification of the iterative algorithm provides acceptable solutions. Even though the global optimum cannot be found amidst the immense number of local optima, several sample problems demonstrate the value of the techniques developed.A companion paper will extend this work to the dynamic routing problem, of deciding how to route future demands and install transmission facilities so as to minimize the present worth of expenditures during the study interval. The methods and goals of these modeling efforts will be discussed in the companion paper.
On some techniques useful for solution of transportation network problems
Authors: Tomizawa N. 
Published: May 2007

AbstractThis paper presents an efficient algorithm for solving transportation problems. The improvement over the existing algorithms of the “primal‐dual” type [3], [5] consists in modifying the “potential‐raising” stages of the solution process in such a way that negative‐cost arcs are removed so that the Dijkstra's algorithm may be applied. Especially, the algorithm requires at most n3 additions and comparisons when applied to an n‐by‐n assignment problem, as compared with the theoretical upper bound proportional to n4 for the number of such operations required by currently available methods. Furthermore, auxiliary techniques of simplifying the original network by means of “reduction” and “induction” are also introduced as useful tools to treat large‐scale problems and specially‐structured problems with.
A simple derivation of edmonds' algorithm for optimum branchings
Authors: Karp R. M. 
Published: May 2007

AbstractEdmonds [1] has given an algorithm for constructing a maximum‐weight branching in a weighted directed graph. His proof that the algorithm is correct is based on linear programming theory, and establishes as a by‐product that a certain polyhedron has integer vertices. Here we give a direct combinatorial proof of the correctness of the algorithm.
Two‐way traffic in loop service systems
Authors: Konheim A. G. , Meister B. 
Published: May 2007

AbstractA model for a communication system which consists of a computer and a number of buffered terminals connected by means of a loop channel is analyzed. Data flows in two directions: from the computer to the terminals and from the terminals to the computer. The channel is alternately available to the computer and the terminals to effect these data transfers. The transient behavior of the system is determined and the stationary or limiting expected queue lengths at all terminals are calculated.
A generalized upper bounding algorithm for multicommodity network flow problems
Authors: Hartman J. K. , Lasdon L. S. 
Published: May 2007

AbstractAn algorithm for solving min‐cost or max‐flow multicommodity flow problems is described. It is a specialization of the simplex method, which takes advantage of the special structure of the multicommodity problem. The only nongraph or nonadditive operations in a cycle involve the inverse of a working basis, whose dimension is the number of currently saturated arcs. Efficient relations for updating this inverse are derived.
Stability of networks with distributed and nonlinear elements. I
Authors: Schwyn P. J. , Bickart T. A. 
Published: May 2007

AbstractThis paper, in two parts, considers the stability of electrical networks consisting of transmission lines interconnected with lumped linear and memoryless nonlinear elements. Let xt be the state of such a network represented as a point in the space C([‐∞, 0], En) of bounded continuous functions mapping the interval [‐∞, 0] into En and let x(t) = xt (0). Then large classes of such networks may be described by an integro‐differential equation of the formmagnified imagewhere A is a real n × n matrix, G(τ) is a real n x n matrix‐valued function of bounded variation on [‐∞,0], and E is a nonlinear function mapping En into En. The integral is of the Riemann‐Stieltjes type.A functional is defined on a subset of C and used to obtain stability theorems for the integro‐differential equation using Liapunov stability theory as extended to functional differential equations. Then, these theorems are applied to networks with transmission lines, with the result being stability criteria which depend only on the lumped elements and the total variation of the step response of the transmission lines with suitably chosen terminations. The total variations associated with uniform, distortionless LC lines and nonuniform RC lines are presented. For networks with RC lines the stability criteria are simplified such that they are functions only of the lumped elements and the total resistances of the RC lines.
Computer‐aided interconnection routing: General survey of the state‐of‐the‐art
Authors: Nakahara H. 
Published: May 2007

AbstractThis paper is a brief survey of the computer‐aided interconnection routing techniques currently in use at various facilities as part of their software packages. It summarizes the pros and cons of the techniques available and also indicates further research areas in the future.Excellent review papers similar to the one presented here have been published previously [26,55,56], which cover a wider range of subjects on design automation in general. Many of the subjects mentioned in the above references are deliberately repeated here since the current paper is intended for tutorial purposes. Those who are interested in the present and related topics are urged to read the aforementioned references.
Dynamic transshipment networks: An algorithm and its application to the distribution of empty containers
Authors: White W. W. 
Published: May 2007

AbstractThe movement of vehicles and goods in a transportation system can be represented as flows through a time‐dependent transshipment network. An inductive out‐of‐kilter type of algorithm is presented which utilizes the basic underlying properties of the dynamic transshipment network to optimize the flow of a homogeneous commodity through the network, given a linear cost function. The algorithm is illustrated by its application to the problem of distributing empty containers from locations at which they are available to locations at which they are required.
Decoupling joint and elastic accelerations in deformable mechanical systems using non‐linear recursive formulations
Authors: Hwang Yunn‐Lin 
Published: May 2007

AbstractThe aim of this paper is to develop non‐linear recursive formulations for decoupling joint and elastic accelerations, while maintaining the non‐linear inertia coupling between rigid body motion and elastic deformation in deformable mechanical systems. The inertia projection schemes used in most existing recursive formulations for the dynamic analysis of deformable mechanisms lead to dense coefficient matrices in the equations of motion. Consequently, there are strong dynamic couplings between the joint and elastic coordinates. When the number of elastic degrees of freedom increases, the size of the coefficient matrix in the equations of motion becomes large. Consequently, the use of these recursive formulations for solving the joint and elastic accelerations becomes less efficient. In this paper, the non‐linear recursive formulations have been used to decouple the elastic and joint accelerations in deformable mechanical systems. The relationships between the absolute, elastic and joint variables and generalized Newton–Euler equations are used to develop systems of loosely coupled equations that have sparse matrix structure. By using the inertia matrix structure of deformable mechanical systems and the fact that joint reaction forces associated with elastic coordinates do represent independent variables, a reduced system of equations whose dimension is dependent of the number of elastic degrees of freedom is obtained. This system can be solved for the joint accelerations as well as for the joint reaction forces. The use of the approaches developed in this investigation is illustrated using deformable open‐loop serial robot and closed‐loop four‐bar mechanical systems. Copyright © 2007 John Wiley & Sons, Ltd.
Analysis, design, and optimization of structures with integral compliant mechanisms for mid‐frequency response
Authors: Dede Ercan M. , Hulbert Gregory M. 
Published: May 2007

AbstractA multi‐scale paradigm is proposed that utilizes periodic, small‐scale, integral compliant mechanisms within larger‐scale structures for the attenuation of vibro‐acoustic response. Amplification principles serve as the basis for the design of these mechanisms in achieving reduced energy transmission. The spectral finite element method is exploited for a force–velocity and energy flow analysis of the resultant truss‐like structures. A genetic algorithm is employed to optimize structure size for greatest effectiveness in the frequency range of interest. This study demonstrates that a significant decrease in structural vibration is achievable and suggests promising applications including the design of acoustic isolation panels for broadband vehicle noise reduction. Copyright © 2007 John Wiley & Sons, Ltd.
Evaluation of elastic modulus of polymer matrix nanocomposites
Authors: Saber‐Samandari Saeed , Afaghi‐Khatibi Akbar 
Published: May 2007

AbstractA new model to evaluate the elastic modulus of polymer nanocomposites is developed with emphasising on the role of inclusion/matrix interphase. The new model can be applied to polymer nanocomposites reinforced by inclusions with different shapes including spherical, cylindrical, and platelet. After validating the new model using experimental and FEA results, the effects of several parameters such as inclusion shape and modulus, d‐spacing, and matrix properties on the elastic modulus of nanocomposites are investigated. POLYM. COMPOS., 28:405–411, 2007. © 2007 Society of Plastics Engineers
Determination of atom displacement distribution in YBCO superconductors induced by gamma radiation
Authors: Piñera I. , Cruz C. M. , Abreu Y. , Leyva A. 
Published: May 2007

AbstractThe calculation results of the atom displacement distribution induced by gamma radiation in the superconducting material YBa2Cu3O7–xare presented. Firstly, a direct calculation procedure for the atom displacement distribution inside a given material is introduced, starting from the application of the energy flux distribution values of secondary electrons, formerly calculated using the Monte Carlo method based code system MCNP‐4C. Finally, calculation results of the atom displacement distribution, regarding the occupied oxygen crystalline sites, are presented for different incident gamma radiation energies, where an atom displacement threshold energy value of 20 eV was assigned to O(1–3) sites, while a value of 3.45 eV was used for the copper–oxygen chain sites at the basal plane. According to the present calculations, a predominating atom displacement rate at copper‐oxygen chain sites was obtained. On the other hand, nearly linear correlations among atom displacements and energy deposition profiles were also found. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gate‐lag and drain‐lag effects in (GaN)/InAlN/GaN and InAlN/AlN/GaN HEMTs
Authors: Kuzmik J. , Carlin J.‐F. , Gonschorek M. , Kostopoulos A. , Konstantinidis G. , Pozzovivo G. , Golka S. , Georgakilas A. , Grandjean N. , Strasser G. , Pogany D. 
Published: May 2007

AbstractGate and drain‐lag effects are studied in (GaN)/InAlN/GaN and InAlN/AlN/GaN HEMTs grown on sapphire. Electron trapping on the surface states between the gate and the drain forming the net negative charge up‐to ∼2 × 1013 cm–2 is found to be responsible for the gate‐lag effect in the (GaN)/InAlN/GaN HEMTs. If the polarization charge at the device surface is decreased by GaN capping, then density of the trapped charge is not changed, however the electron de‐trapping process becomes faster. The drain‐lag effect is caused by electron injection and trapping in the source‐gate area reaching ∼1 × 1013 cm–2 of the trapped charge in the steady state. In the studied voltage range the InAlN/AlN/GaN HEMT is shown to be gate‐lag‐free suggesting that this parasitic transient can be avoided if thin AlN is used in the epi‐layer growth sequence. It is assumed that this breakthrough quality relates to the decreased or even reverted electric field in the InAlN layer if AlN is inserted. Surface states need not to be generated in this case. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)