bluuebunny/crossref_metadata_2025_split huggingface dataset:
An adaptive dynamic programming algorithm for a stochastic multiproduct batch dispatch problem
Authors: Papadaki Katerina P. , Powell Warren B. 
Published: September 2003

AbstractWe address the problem of dispatching a vehicle with different product classes. There is a common dispatch cost, but holding costs that vary by product class. The problem exhibits multidimensional state, outcome and action spaces, and as a result is computationally intractable using either discrete dynamic programming methods, or even as a deterministic integer program. We prove a key structural property for the decision function, and exploit this property in the development of continuous value function approximations that form the basis of an approximate dispatch rule. Comparisons on single product‐class problems, where optimal solutions are available, demonstrate solutions that are within a few percent of optimal. The algorithm is then applied to a problem with 100 product classes, and comparisons against a carefully tuned myopic heuristic demonstrate significant improvements. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 742–769, 2003.
A specially structured nonlinear integer resource allocation problem
Authors: Bretthauer Kurt M. , Shetty Bala , Syam Siddhartha 
Published: September 2003

AbstractWe present an algorithm for solving a specially structured nonlinear integer resource allocation problem. This problem was motivated by a capacity planning study done at a large Health Maintenance Organization in Texas. Specifically, we focus on a class of nonlinear resource allocation problems that involve the minimization of a convex function over one general convex constraint, a set of block diagonal convex constraints, and bounds on the integer variables. The continuous variable problem is also considered. The continuous problem is solved by taking advantage of the structure of the Karush‐Kuhn‐Tucker (KKT) conditions. This method for solving the continuous problem is then incorporated in a branch and bound algorithm to solve the integer problem. Various reoptimization results, multiplier bounding results, and heuristics are used to improve the efficiency of the algorithms. We show how the algorithms can be extended to obtain a globally optimal solution to the nonconvex version of the problem. We further show that the methods can be applied to problems in production planning and financial optimization. Extensive computational testing of the algorithms is reported for a variety of applications on continuous problems with up to 1,000,000 variables and integer problems with up to 1000 variables. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 770–792, 2003.
Optimal retail assortments for substitutable items purchased in sets
Authors: Agrawal Narendra , Smith Stephen A. 
Published: September 2003

AbstractWe consider the problem of optimizing assortments in a multi‐item retail inventory system. In addition to the usual holding and stockout costs, there is a fixed cost for including any item in the assortment. Customers' preferences for items include both probabilistic substitution patterns and the desire to purchase sets of complementary items. We develop a demand model to capture this behavior, and derive tractable approximations that allow us to formulate the optimization problem as a 0–1 mixed integer linear program. Numerical examples are solved to illustrate key insights into how both complementary and substitute items affect the optimal assortment and the expected profit. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 793–822, 2003.
Exact algorithms for scheduling multiple families of jobs on parallel machines
Authors: Chen Zhi‐Long , Powell Warren B. 
Published: September 2003

AbstractIn many practical manufacturing environments, jobs to be processed can be divided into different families such that a setup is required whenever there is a switch from processing a job of one family to another job of a different family. The time for setup could be sequence independent or sequence dependent. We consider two particular scheduling problems relevant to such situations. In both problems, we are given a set of jobs to be processed on a set of identical parallel machines. The objective of the first problem is to minimize total weighted completion time of jobs, and that of the second problem is to minimize weighted number of tardy jobs. We propose column generation based branch and bound exact solution algorithms for the problems. Computational experiments show that the algorithms are capable of solving both problems of medium size to optimality within reasonable computational time. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 823–840, 2003.
A numerical model for induction heating processes coupling electromagnetism and thermomechanics
Authors: Bay F. , Labbe V. , Favennec Y. , Chenot J. L. 
Published: September 2003

AbstractThis paper presents a mathematical and numerical model developed for coupling the various physical phenomena (electromagnetic, thermal and mechanical) taking place in axisymmetrical induction heating processes. All three electromagnetic, thermal and mechanical models are time dependent and take full account of the electromagnetic and thermal non‐linear effect especially with magnetic materials. The electromagnetic problem is discretized and solved in the workpiece, air and inductors. The heat transfer equation and the mechanical equilibrium equations are solved in the workpiece only, both using a finite element method. The mechanical model can take into account thermoelastic–plastic behaviour for the part. The model has been successfully applied to several cases of induction heating. Comparisons between numerical and experimental results show an excellent agreement. Copyright © 2003 John Wiley & Sons, Ltd.
The meshless finite element method
Authors: Idelsohn Sergio R. , Oñate Eugenio , Calvo Nestor , Del Pin Facundo 
Published: September 2003

AbstractA meshless method is presented which has the advantages of the good meshless methods concerning the ease of introduction of node connectivity in a bounded time of order n, and the condition that the shape functions depend only on the node positions. Furthermore, the method proposed also shares several of the advantages of the finite element method such as: (a) the simplicity of the shape functions in a large part of the domain; (b) C0 continuity between elements, which allows the treatment of material discontinuities, and (c) ease of introduction of the boundary conditions. Copyright © 2003 John Wiley & Sons, Ltd.
Identification of coating defects in cathodically protected underground pipelines
Authors: Miltiadou Panayiotis , Wrobel Luiz C. 
Published: September 2003

AbstractCoating defects may occur, for many different reasons, at some points on the surface of a cathodically protected structure. These defects behave anodically and may cause strong localized corrosion. It is possible to identify the position of coating defects by using measured values of the electrochemical potential at some points in the electrolyte or on its surface. To achieve this, an inverse BEM‐based genetic algorithm is developed to identify the position of defects in cathodically protected underground pipelines. The formulation is validated through its application to practical problems involving strongly non‐linear polarization curves, infinite electrolytes, unknown number of defects and measurement noise. Copyright © 2003 John Wiley & Sons, Ltd.
Improved conditioning of infinite elements for exterior acoustics
Authors: Dreyer D. , von Estorff O. 
Published: September 2003

AbstractAn optimized version of the so‐called mapped wave envelope elements, also known as Astley–Leis elements, is introduced. These elements extend to infinity in one dimension and therefore provide an approach to the simulation of exterior acoustical problems in both frequency and time domains. Their formulation is improved significantly through the proper choice of polynomial bases in the direction of radiation. In particular, certain Jacobi polynomials are identified which behave well with respect to conditioning of the system matrices. As a consequence, the size of the finite element discretization may reduce considerably without any loss of accuracy. In addition, the new polynomial bases lead to superior performance of the infinite elements in conjunction with iterative solvers. Copyright © 2003 John Wiley & Sons, Ltd.
A Gaussian sinc‐collocation approach for a whipping cantilever with a follower shear force at its tip
Authors: Reid S. R. , Roy D. 
Published: September 2003

AbstractA spatial discretization scheme, based on a set of Gaussian sinc functions, is proposed for the temporal projection of a set of partial differential equations (PDEs), describing the non‐linear dynamics of an elastic–plastic hardening–softening (EPHS) cantilever, subjected to a follower shear force at its tip. The dynamics so described correspond to planar whipping of a pipe conveying fluid, ruptured near a right‐angled bend. The constitutive EPHS moment curvature relationship used here follows the earlier work of Reid et al. (Proceedings of the Royal Society of London, Series A 1998; 454: 997–1029). Compared to the more classical Lagrangian polynomial‐based collocation functions, the Gaussian sinc functions have better localization properties. Moreover, for a relatively large number of collocation points, use of such functions does not lead to numerical overflow or underflow problems, often associated with the use of higher order polynomial collocation functions. The spatial discretization leads to a set of non‐linear ordinary differential equations (ODEs) in time, which are in turn integrated via a fourth order adaptive Runge–Kutta scheme. Some numerical results for a cantilever whipping in a plane are presented to further illustrate the present approach. The method is a step forward towards the development of a mesh‐free non‐linear beam element, suitable for dynamic analyses of pipe networks and pipe‐on‐pipe impact problems. Copyright © 2003 John Wiley & Sons, Ltd.
Multiple fully stressed designs of steel frame structures with semi‐rigid connections
Authors: Liu Min , Burns Scott A. 
Published: September 2003

AbstractA fully stressed design of a frame structure, in which each member is performing to its maximum safe level under at least one loading case, is a common goal in structural design. When multiple fully stressed designs are possible, the designer must make some decisions regarding the desired load path because the outcome of the iterative fully stressed design computation depends upon the initial starting design selected. When steel frame structures are modelled as having semi‐rigid beam‐to‐column connections, the connection flexibility has a significant impact on the nature and diversity of potential fully stressed designs. This paper presents a computational study of how the variety of potential fully stressed designs is affected by connection flexibility. A numerical algorithm, which combines the stress ratio method and Newton's method to avoid problems associated with each method when used alone, is applied to generate sets of distinct fully stressed designs as connection flexibility is varied. It is found that as the connections become increasingly flexible, the variety of fully stressed designs diminishes. Load paths that are efficient with rigid connections are not realizable with semi‐rigid connections because of limited bending moment transfer capacity and, consequently, limited alternate load paths. Copyright © 2003 John Wiley & Sons, Ltd.
On the Pareto optimum sensitivity analysis in multicriteria optimization
Authors: Zhang W. H. 
Published: September 2003

AbstractTo analyse the trade‐off relations among the set of criteria in multicriteria optimization, Pareto optimum sensitivity analysis is systematically studied in this paper. Original contributions cover two parts: theoretical demonstrations are firstly made to validate the gradient projection method in Pareto optimum sensitivity analysis. It is shown that the projected gradient direction evaluated at a given Pareto optimum in the design variable space rigorously corresponds to the tangent direction of the Pareto curve/surface at that point in the objective space. This statement holds even for the change of the set of active constraints in the perturbed problem. Secondly, a new active constraint updating strategy is proposed, which permits the identification of the active constraint set change, to determine the influence of this change upon the differentiability of the Pareto curve and finally to compute directional derivatives in non‐differentiable cases. This work will highlight some basic issues in multicriteria optimization. Some numerical problems are solved to illustrate these novelties. Copyright © 2003 John Wiley & Sons, Ltd.
Differential effects of depolarization on intracellular calcium concentration in wild type and dunce Drosophila neurons
Authors: Alshuaib W.B. , Hasan M.Y. , Cherian S.P. , Fahim M.A. 
Published: September 2003

AbstractUtilizing Fura 2‐AM fluorescence photometry, intracellular calcium concentration ∥[Ca2+]i) was measured in wild type and dunce cleavage‐arrested Drosophila neurons under resting condition and in response to KCl induced depolarization. Following KCl application, peak [Ca2+]i was greater in dunce (424 ± 29 nM) than in wild type neurons (246 ± 21 nM). Half decay time was shorter in dunce (65 ± 5 sec) than in wild type neurons (84 ± 6 sec). In cadmium‐containing and in calcium‐free external solutions, KCl application did not lead to any changes in [Ca2+]i in wild type and dunce neurons. Thus, the source of increase in [Ca2+]i seems to be Ca2+ influx from outside. Treatment with nifedipine and nimodipine did not affect [Ca2+]i increase in response to KCl application. This indicates that both wild type and dunce neuronal Ca2+ channels are not sensitive to these dihydropyridines. Pretreatment of wild type neurons with dibutyryl cAMP for 1 hour, prior to depolarization by KCl, resulted in peak [Ca2+]i of 369 ± 27 nM which is similar to untreated dunce neurons. The present results suggest that cAMP is implicated in modulating Ca2+ channels leading to enhanced Ca2+ influx in dunce neurons. Calcium extrusion and/or calcium buffering systems are possibly enhanced in the dunce mutant compared to the wild type. This disturbance in homeostatis of cytosolic calcium concentration in dunce neurons may be implicated in defective learning and memory.
Effect of melatonin on β‐amyloid peptide overexpression and memory impairment in a rat AD‐model and the influence of bicuculline
Authors: Xu Haiwei , Fan Xiaotang , Gao Enquan , Wu Xuan , Cao Juan , Li Haidi 
Published: September 2003

AbstractMelatonin deficiency in cerebrospinal fluid has been postulated to be critical for the development of Alzheimer Disease (AD). As a potent free radical scavengers and antioxidant, melatonin has been proposed to delay or inhibit progression of neurodegenertion in AD. Since the effect of melatonin on Aβ peptide toxicity in the rat oxidative stress model of AD is not fully understood, we observed the effect of melatonin on Aβ protein and APP mRNA in the hippocampus and frontal cortex of AD rats model established by Bennett and found melatonin inhibited the Aβ and APP mRNA. The effect of melatonin could be partly attenuated by pretreatment with the GABA antagonist bicuculline. The results suggest melatonin reduced the Aβ production probably by inhibiting overexpression of APP in the CNS of AD model rats. Maybe these effects of melatonin were influenced by GABA.
A NOS inhibitor aminoguanidine reduces zinc‐induced neuron loss in rat hippocampus
Authors: Gokçe F.M. , Bağirici F. , Kaplan S. , Demir Ş. , Ayyildiz M. , Marangoz C. 
Published: September 2003

AbstractThere are many studies on zinc as a possible cause of neuronal hyperactivity and cell death. The present study was designed to investigate the changes in total pyramidal cell number of rat hippocampus after intracortical zinc sulphate (ZnSO4, 200 μg/kg, i.c.) and a nitric oxide synthase (NOS) inhibitor aminoguanidine (AG) administration. Animals were divided into three groups as control, zinc and the treatment (zinc+AG) groups. Each group was divided into two subgroups, as 7‐day group and 15‐day group. Zinc sulphate was injected intracortically into 2 mm lateral of Bregma. The same volume of saline (2μl) was given to the rats belonging to the control groups. Rats in the third group were given ZnSO4 + AG in the same injection point. Animals in the third group only received 100 mg/kg AG intraperitoneally twice a day for periods of 7 or 15 days. Total pyramidal neuron number was estimated using the optical fractionator method. The total number of pyramidal cells found in the left hippocampus was 653,468 ± 3,452 and 601,860 ± 3,348 in the control groups; 257,968 ± 1,277 and 250,555 ± 1,443 in the zinc groups; 382,519 ± 1,973 and 365,880 ± 2,658 in the treatment groups in 7‐day post treatment and 15‐day post treatment rats, respectively.These results suggest that zinc has a neurotoxic effect on pyramidal neurons in rat hippocampus (p<0.05) and an inhibitor of nitric oxide synthase, AG, decreases cell loss (p<0.05). This shows that nitric oxide (NO) contributes to this type of neurotoxicity in the rat hippocampus and also suggests a possible therapeutic role for NOS inhibitor in neurodegenerative diseases.
An antitoxidant formulation that induces differentiation of neuroblastoma in culture
Authors: Hancock Amy L. , Nakuci Enkeleda , Nicolosi Robert J. , Shea Thomas B. 
Published: September 2003

AbstractNeuroblastoma, the most common of all cancers found in children, may arise from a block of differentiation and a resultant continuation of the proliferative state. Neuroblastoma often spontaneously revert by undergoing partial differentiation and ultimate degeneration. A useful therapeutic approach for clinical neuroblastoma may encompass strategies to force neuroblastoma to differentiate. In ongoing studies on neuronal health, we have developed an anti‐oxidant synergy formulation (“ASF”), comprised of α‐tocopherol (vitamin E), sodium pyruvate and phosphatidyl choline, which lessens neurotoxicity and promotes axonal elaboration in cultured neurons. We demonstrate herein that ASF prevents proliferation and promotes differentiation of neuroblastoma in culture, even in the presence of serum, which normally induces rapid neuroblastoma proliferation in culture. These data leave open the possibility that ASF, with proper administration, may foster differentiation, and therefore ultimate degeneration, of neuroblastoma in situ, and may therefore represent a novel approach towards suppression of clinical neuroblastoma.
Micro‐phase‐separation behavior of amphiphilic polyurethanes involving poly(ethylene oxide) and poly(tetramethylene oxide)
Authors: Lee Daewon , Lee Seung‐Heon , Kim Sangcheol , Char Kookheon , Park Jae Hyung , Bae Yoo Han 
Published: September 2003

AbstractThe temperature dependence of thermal, morphological, and rheological properties of amphiphilic polyurethanes was examined with differential scanning calorimetry (DSC), wide‐angle X‐ray scattering (WAXS), small‐angle X‐ray scattering (SAXS), rheological measurements, and Fourier transform infrared spectroscopy. Multiblock (MPU) and triblock (TPU) polyurethanes were synthesized with two crystallizable segments—poly(ethylene oxide) (PEO) as a hydrophilic block and poly(tetramethylene oxide) (PTMO) as a hydrophobic block. DSC and WAXS measurements demonstrated that the microphase of MPUs in the solid state is dominantly affected by the PEO crystalline phase. However, high‐order peaks were not observed in the SAXS measurements because the crystallization of the PEO segments in MPUs was retarded by poor sequence regularity. The microphase in the melt state was induced by the hydrogen bonding between the NH group of hexamethylene diisocyanate linkers and the ether oxygen of PEO or PTMO blocks. As the temperature increased, the smaller micro‐phase‐separated domains were merged into the larger domains, and the liquidlike ordering was eventually disrupted because of the weakening hydrogen bonding. However, the fully homogeneous state of an MPU with a molar ratio of 5/5 PEO/PTMO (MPU55) was not confirmed even at much higher temperatures with both SAXS and rheological measurements. However, the SAXS patterns of TPU showed weak but broad second‐order peaks below the melting temperature of the PEO block. Compared with MPU55, the ordering of the TPU crystalline lamellar stacks was enhanced because of the high sequence regularity and the low hydrogen‐bonding density. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2365–2374, 2003
Gel formation with multiple interunit junctions. II—mixture of different functional molecules
Authors: Tanaka Fumihiko 
Published: September 2003

AbstractNumber‐ and weight‐average molecular weight of condensation polymers formed in the mixture of primary molecules carrying different species of functional groups A and B are derived by the cascade theory. These functional groups are allowed to form multiple junctions of arbitrary multiplicity k. From the weight average, the gel point condition is found to be given by 1 − (fw − 1)(μA,A − 1) − (gw − 1)(μB,B − 1) + (fw − 1)(gw − 1)Dμ = 0, where fw and gw are average functionality of the primary molecules, μαβ the average multiplicity of β groups in the junctions where a path of an α‐group enters, and Dμ ≡ (μA,A − 1)(μB,B − 1) − μA,BμB,A the multiplicity determinant. Possible applications to thermoreversible gelation are suggested. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2413–2421, 2003
Do epoxy–amine networks become inhomogeneous at the nanometric scale?
Authors: Duchet J. , Pascault J. P. 
Published: September 2003

AbstractEpoxy–amine networks are known to be homogeneous. However, using new analysis tools that allow the observation scale to be reduced to a nanometric level, some authors have stated the opposite. In this work, the network morphology has been studied with atomic force microscopy in the tapping mode as a function of the hardener nature and the stoichiometry of the reactive blend. A very homogeneous epoxy network topography, similar to that of an amorphous thermoplastic, has been obtained. For comparison, a truly heterogeneous network topography, like that of unsaturated thermosets cured by free‐radical mechanisms, has been imaged. For the observation of surfaces on a scale smaller than a nanometer, caution must be taken:(1) the tips must be freshly cleaned so that distortion on the image is prevented and (2) the surfaces must be very flat so that the phase contrast is not influenced significantly by differences in the sample topography. This works gives guidelines on using atomic force microscopy in the tapping mode for epoxy–amine network characterization and discusses epoxy–amine network homogeneity. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2422–2432, 2003
Gel formation with multiple interunit junctions. I—Molecules carrying different functional groups
Authors: Tanaka Fumihiko 
Published: September 2003

AbstractNumber‐ and weight‐average molecular weight of condensation polymers formed by primary molecules carrying different species of functional groups {Ai} (i = 1, 2, …, s) are derived by cascade theory. These functional groups are allowed to form multiple junctions of variable multiplicity k. The gel point condition is found to be given by ∑ wi/|μw,i + 1/∑ fi − 1 = 0, where fi is the number of Ai groups specified by the index i on a primary molecule, wi ≡ fi/∑ fi the number fraction of the species i it carries, and |μw,i the weight average multiplicity of the junctions formed by the groups Ai. The explicit form of the molecular weight distribution function is found for the simplest case of two components. Possible application to thermoreversible gelation is suggested. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2405–2412, 2003