bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling and Solving the Train Timetabling Problem
Authors: Caprara Alberto , Fischetti Matteo , Toth Paolo 
Published: January 2003

The train timetabling problem aims at determining a periodic timetable for a set of trains that does not violate track capacities and satisfies some operational constraints. In particular, we concentrate on the problem of a single, one-way track linking two major stations, with a number of intermediate stations in between. Each train connects two given stations along the track (possibly different from the two major stations) and may have to stop for a minimum time in some of the intermediate stations. Trains can overtake each other only in correspondence of an intermediate station, and a minimum time interval between two consecutive departures and arrivals of trains in each station is specified. In this paper, we propose a graph theoretic formulation for the problem using a directed multigraph in which nodes correspond to departures/arrivals at a certain station at a given time instant. This formulation is used to derive an integer linear programming model that is relaxed in a Lagrangian way. A novel feature of our model is that the variables in the relaxed constraints are associated only with nodes (as opposed to arcs) of the aforementioned graph. This allows a considerable speed-up in the solution of the relaxation. The relaxation is embedded within a heuristic algorithm which makes extensive use of the dual information associated with the Lagrangian multipliers. We report extensive computational results on real-world instances provided from Ferrovie dello Stato SpA, the Italian railway company, and from Ansaldo Segnalamento Ferroviario SpA.
Inventory Cost Rate Functions with Nonlinear Shortage Costs
Authors: Rosling Kaj 
Published: January 2003

This article considers five cost-rate models for inventory control, each summarizing the expected holding and shortage costs per period as a function of the inventory position. All models have linear holding costs and shortage cost coefficients of dimension [$/unit/period], [$/unit], and [$/period]. The latter two coeficients may be the shadow costs of a fill-rate and a ready-rate service constraint, respectively. One of the cost-rate models is a new suggestion, intended to facilitate modeling of periodic-review inventory systems. If-and-only-if conditions on the demand process are presented for which the cost rate is quasi-convex in the inventory position. The typical sufficient condition requires that the cumulative demand distribution be logconcave, a condition that is met by most demand distributions commonly used in the inventory literature. The results simplify optimization and extend the known optimality of (S, s) and (nQ, r) policies to cost structures common in applications and to the presence of typical service constraints. As a prerequisite for the study, a series of new monotonicity results are derived for compound renewal processes.
Algorithms for Radio Link Frequency Assignment: The Calma Project
Authors: Aardal Karen , Hurkens Cor , Lenstra Jan Karel , Tiourine Sergey 
Published: January 2003

The radio link frequency assignment problem occurs when a network of radio links has to be established. Each link must be assigned an operating frequency from a given domain. The assignment has to satisfy certain restrictions so as to limit the interference between links. The number of frequencies used is to be minimized. Problems of this type were investigated within the CALMA project by a consortium consisting of research groups from Delft, Eindhoven, London, Maastricht, Norwich, and Toulouse. The participants developed optimization algorithms based on branch-and-cut and constraint satisfaction, and approximation techniques including a variety of local search methods, genetic algorithms, neural networks, and potential reduction. These algorithms were tested and compared on a set of real-life instances.
Are Firms Superior to Alliances and Markets? An Empirical Test of Cross-Border Knowledge Building
Authors: Almeida Paul , Song Jaeyong , Grant Robert M. 
Published: January 2003

Are multinational corporations (MNCs) superior to strategic alliances and markets in facilitating the flow of knowledge across borders? If so, what are the sources of this superiority? Despite their central importance to the theory and practice of international management, these questions have not been directly tested. Our paper seeks to address this gap in empirical research.Drawing upon recent research on multinational corporations and the knowledge-based view of the firm, we develop hypotheses regarding the relative superiority of alternative institutional arrangements as regards cross-border knowledge building. Analysis of patent citations by semiconductor companies points to the superiority of multinational firms over both alliances and markets in cross-border knowledge building. Interviews with engineers and managers in MNCs point to the intertwining of codified and tacit knowledge and; therefore, the need for both formal and informal mechanisms for successful knowledge building. Our findings suggest that the superiority of MNCs stems from the firms' ability to use multiple mechanisms of knowledge transfer flexibly and simultaneously to move, integrate, and develop technical knowledge. Our research, therefore, suggests that the challenge of knowledge management for MNCs extends beyond the creation of international information systems, to the design of organizational structures, systems, and culture capable of supporting the flow of knowledge.
Agency and Institutions: National Divergences in Diversification Behavior
Authors: Kogut Bruce , Walker Gordon , Anand Jaideep 
Published: January 2003

A fundamental theme in comparative crosscountry research is the convergence of organizational forms in diverse national settings. In this paper we examine a special instance of this theme: the pattern of diversification across industries. A common argument is that technical and market forces compel firms to adopt “coherent” strategies of diversification. This thesis implies that there should be a convergence in the patterns of interindustry diversification in all market-based economies. An institutional approach offers an alternative view. From this perspective, when diversification across industries is seen as subject to nation-specific governance and resource constraints, countries should vary widely in their interindustry diversification patterns. To test these alternative views, we analyze the diversification patterns of large corporations from five countries: France, Germany, Japan, the United Kingdom, and the United States. Our results do not support the hypothesis of a common pattern of diversification across countries, and thus reject the technological thesis. By comparing two case studies in which entrepreneurs attempted to diversify by acquisition in France and the United States, we examine how institutions and agents interact to permit different diversification patterns to arise in diverse national environments. The statistical results and case studies imply that, given the fixity of certain institutions, even if countries are subject to globalization, convergence in diversification patterns is not necessary. The results cast doubt upon the merits of stylizing the debate as a choice between technical and institutional theories of organizational choice. Rather, the study points to the importance of two theoretical statements. The first is to inquire under what conditions there is likely to be consensus on a given “means-end” rationality for a specific managerial decision (e.g., diversification). The second is to understand the structural opportunities available to entrepreneurs for diversifying through acquisitions. Iterating between these cognitive and structural considerations shifts the focus from the false debate between technological and institutional arguments to the study of entrepreneurship situated in historically given national environments.
A Heuristic Search Approach for a Nonstationary Stochastic Shortest Path Problem with Terminal Cost
Authors: Bander James L. , White Chelsea C. 
Published: January 2003

We present a best-first heuristic search approach for determining an optimal policy for a stochastic shortest path problem. A vehicle is to travel from an origin, starting at time t0, to a destination, where once the destination is reached a terminal cost is accrued. The terminal cost depends on the time of arrival. Travel time along each arc in the network is modeled as a random variable with a distribution dependent on the time that travel along the arc is begun. The objective is to determine a routing policy that minimizes expected total cost. A routing policy is a rule that assigns the next arc to traverse, given the current node and time. The heuristic search algorithm that we specialize to this stochastic problem is AO*. We demonstrate the significant computational advantages of AO*, relative to dynamic programming, on the basis of run time and storage, using a 131-intersection network of the major roads in Cleveland, Ohio. Further computational experience is based on grid networks that were randomly generated to have characteristics similar to transportation networks, and on randomly generated unstructured networks.
Validation of the Dutch version of the aggression questionnaire in adolescent male offenders
Authors: Morren Mattijn , Meesters Cor 
Published: January 2003

AbstractThis study examined the construct validity of the Dutch version of Buss and Perry’s Aggression Questionnaire (AQ) in 73 adolescent male offenders aged 12 to 18 years who were participating in a residential rehabilitation program. There was a strong positive association between the Hostility subscale of the AQ and psychological and physical symptoms. The nature of this connection was discussed. It was argued that the Hostility subscale measures some unique aspect of aggression that is not incorporated by the Physical Aggression, Verbal Aggression, or Anger subscales of the AQ. As expected, the AQ scales correlated significantly with trait anger, social desirability, and age. Furthermore, staff ratings of physical violence, verbal aggression, anger, and negative attitude were obtained for each subject. Correlations between the AQ scales and these ratings were low. Possible explanations for this unexpected finding are discussed. Finally, normative and internal structure data are presented. Aggr. Behav. 28:87–96, 2002. © 2002 Wiley‐Liss, Inc.
Reduction of dimensionality in choosing optimal control
Authors: Khazen Ellida M. 
Published: January 2003

AbstractGiven thatx(t) = (x1(t),…,xn(t)) represents a trajectory of the considered dynamical system, we demonstrate that reduction of dimensionality ofx(t) by using its principal components in choosing the optimal controlu(t) is necessary to overcome the computational difficulties that might arise in obtaining a solution of the optimal control problem. We obtain explicit solutions for linear time‐varying systems with quadratic cost functional and show how to overcome difficulties appearing in non‐linear matrix differential equations of Riccati type. A gradient method of searching for the close‐to‐optimal trajectory and control in non‐linear optimal control problems is also considered. Copyright © 2002 John Wiley & Sons, Ltd.
A new adaptive backstepping control algorithm for motion control systems — an implicit and symbolic computation approach
Authors: Yu Jen‐te , Chang Jie 
Published: January 2003

AbstractA new adaptive integral backstepping control algorithm for motion control systems is proposed. The design approach is non‐conventional in that it only implicitly incorporates error states into a design Lyapunov function and computes time derivative of the Lyapunov function symbolically to the point of getting parameter estimate update laws on which desirable structures are imposed. The closed‐loop error system turns out to be linear and time‐varying and can be reformulated as a linear–non‐linear cascade system. Uniform exponential stability or absolute stability can be achieved. The design is robust against system parameter variations. The effectiveness and robustness of the control algorithm are verified by numerical examples. Copyright © 2002 John Wiley & Sons, Ltd.
Identification of a class of non‐linear parametrically varying models
Authors: Previdi F. , Lovera M. 
Published: January 2003

AbstractThe aim of this paper is to propose a novel class of non‐linear, possibly parameter‐varying models suitable for system identification purposes. These models are given in the form of a linear fractional transformation (LFT) where the ‘forward’ part is represented by a conventional linear regression and the ‘feedback’ part is given by a non‐linear dynamic map parameterized by a neural network (NN) which can take into account scheduling variables available for measurement.For this specific model structure a parameter estimation procedure has been set up, which turns out to be particularly efficient from the computational point of view. Also, it is possible to establish a connection between this model class and the well known class of local model networks (LMNs): this aspect is investigated in the paper. Finally, we have applied the proposed identification procedure to the problem of determining accurate non‐linear models for knee joint dynamics in paraplegic patients, within the framework of a functional electrical stimulation (FES) rehabilitation engineering project. Copyright © 2002 John Wiley & Sons, Ltd.
Bayesian estimation of traffic lane state
Authors: Nagy Ivan , Kárný Miroslav , Nedoma Petr , Voráčová Šárka 
Published: January 2003

AbstractModelling of large transportation systems requires a reliable description of its elements that can be easily adapted to the specific situation. This paper offers mixture model as a flexible candidate for modelling of such element. The mixture model describes particular and possibly very different states of a specific system by its individual components. A hierarchical model built on such elements can describe complexes of big city communications as well as railway or highway networks.Bayesian paradigm is adopted for estimation of parameters and the actual component label of the mixture model as it serves well for the subsequent decision making. As a straightforward application of Bayesian method to mixture models leads to infeasible computations, an approximation is applied. For normal stochastic variations, the resulting estimation algorithm reduces to a simple recursive weighted least squares.The elementary modelling is demonstrated on a model of traffic flow state in a single point of a roadway. The examples for simulated as well as real data show excellent properties of the suggested model. They represent much wider set of extensive tests made. Copyright © 2003 John Wiley & Sons, Ltd.
Lyapunov‐based backward‐horizon adaptive stabilization
Authors: Venugopal Ravinder , Rao Venkatesh G. , Bernstein Dennis S. 
Published: January 2003

AbstractIn this paper we develop a discrete‐time adaptive stabilization algorithm based on a one‐step backward‐horizon cost criterion. By optimizing the cost with respect to the update step size, we obtain a gain update law that guarantees convergence of the plant states. The convergence proof is based on a modified Lyapunov technique. We extend the algorithm to include integral control for rejecting constant disturbances and we present an experimental application to DC motor positioning system. Copyright © 2003 John Wiley & Sons, Ltd.
Selective Hydrogenation for Fine Chemicals: Recent Trends and New Developments
Authors: Blaser Hans‐Ulrich , Malan Christophe , Pugin Benoît , Spindler Felix , Steiner Heinz , Studer Martin 
Published: January 2003

AbstractIn this overview, recent trends and developments for the selective hydrogenation of multifunctional molecules are discussed and assessed from the point of view of fine chemicals synthesis. In a first part, the design and preparation of catalysts and ligands with interesting properties are summarized, particularly meant for the catalysis specialist. The following topics are described in some detail: How enantioselective homogeneous catalysts are designed and tested; new effective chiral monodentate phosphines; successful bidentate phosphines ligand families (with axially chiral biaryl‐ and ferrocenyl‐based backbones, new phospholanes and with stereogenic phosphorus); novel bidentate ligand families with P‐O and P‐N bonds; and oxazoline‐based ligands. A short overview on immobilized chiral complexes and of the toolbox of heterogeneous catalysis (bimetallic, colloidal and modified catalysts) concludes this chapter. In a second part, progress for selected catalytic transformations and generic selectivity problems is described, intended mainly for the organic chemist who has to solve specific synthetic problems. Emphasis is on the following topics: The enantioselective hydrogenation of olefins with various substitution patterns; the chemo‐ and enantioselective hydrogenation of ketones; the diastereo‐ and enantioselective hydrogenation of CN functions; the stereoselective hydrogenation of aromatic rings; chemoselectivity and hydroxylamine accumulation in the reduction of functionalized nitroarenes; chemoselectivity and new protecting groups for catalytic debenzylation; the mild hydrogenation of carboxylic acid derivatives; and the chemoselective hydrogenation of nitriles. In the last parts of the review, transfer hydrogenation and mechanistic issues are discussed, followed by a short conclusions and outlook paragraph.
Towards a Large‐Scale Asymmetric Reduction Process with Isolated Enzymes: Expression of an (S)‐Alcohol Dehydrogenase in E. coli and Studies on the Synthetic Potential of this Biocatalyst
Authors: Hummel Werner , Abokitse Kofi , Drauz Karlheinz , Rollmann Claudia , Gröger Harald 
Published: January 2003

AbstractAn NAD‐dependent and widely applicable (S)‐alcohol dehydrogenase is isolated and described as a novel enzyme. It is expressed in an E. coli strain with a high production potential. The application of this enzyme in asymmetric biocatalytic reduction is presented as well. This enzyme shows a broad substrate range comprising aliphatic and aromatic ketones as well as β‐keto esters. The synthetic application of this new (S)‐alcohol dehydrogenase led to optically active alcohols in high conversion rates accompanied by enantioselectivities of up to >99% ee. Compared to the wild‐type enzyme significant advantages are observed besides the improved availability, such as a high enantioselectivity independent of the reaction time. Furthermore, the alcohol dehydrogenase was cloned and successfully overexpressed in E. coli resulting in a biocatalyst with a potential to be available on technical scale in the future. The development of a large‐scale available and widely applicable (S)‐alcohol dehydrogenase is one prerequisite to use isolated enzymes for asymmetric reduction processes as a valuable tool.
Asymmetric Catalysis: Science and Opportunities (Nobel Lecture 2001)
Authors: Noyori Ryoji 
Published: January 2003

AbstractAsymmetric catalysis, in its infancy in the 1960s, has dramatically changed the procedures of chemical synthesis, and resulted in an impressive progression to a level that technically approximates or sometimes even exceeds that of natural biological processes. The recent exceptional advances in this area attest to a range of conceptual breakthroughs in chemical sciences in general, and to the practical benefits of organic synthesis, not only in laboratories but also in industry. The growth of this core technology has given rise to enormous economic potential in the manufacture of pharmaceuticals, animal health products, agrochemicals, fungicides, pheromones, flavors, and fragrances. Practical asymmetric catalysis is of growing importance to a sustainable modern society, in which environmental protection is of increasing concern. This subject is an essential component of molecular science and technology in the 21st century. Most importantly, recent progress has spurred various interdisciplinary research efforts directed toward the creation of molecularly engineered novel functions. The origin and progress of my research in this field are discussed.
A Novel Class of Ferrocenyl‐Aryl‐Based Diphosphine Ligands for Rh‐ and Ru‐Catalysed Enantioselective Hydrogenation
Authors: Sturm Thomas , Weissensteiner Walter , Spindler Felix 
Published: January 2003

AbstractA series of diphosphines of the novel Walphos ligand family all based on a phenylferrocenylethyl backbone were synthesised in a four‐step sequence. In the rhodium‐ or ruthenium‐catalysed asymmetric hydrogenation of olefins and ketones enantioselectivities of up to 95% and 97%, respectively, were obtained. A 2‐isopropylcinnamic acid derivative of industrial interest was hydrogenated in 95% ee and with turnover numbers of >5000.
Synthesis of Chiral Trifluoromethylated Amines by Palladium‐Catalyzed Diastereoselective Hydrogenation‐Hydrogenolysis Approach
Authors: Török Béla , Surya Prakash G. K. 
Published: January 2003

AbstractThe synthesis of chiral 2,2,2‐trifluoro‐1‐phenylethylamines by palladium‐catalyzed diastereoselective heterogeneous catalytic hydrogenation is described. The one‐pot process involves two steps; the diastereoselective hydrogenation of chiral 2,2,2‐trifluoro‐1‐phenylethyl‐N‐1′‐phenylethylimines and the hydrogenolysis of the methylbenzyl group on the amino function. During both the hydrogenation and hydrogenolysis steps favorable stereoinduction was observed, and the products were obtained in 90–93% ee and 50–55% yield.
Iridium‐Catalyzed Enantioselective Hydrogenation of Imines with Xylose Diphosphite and Diphosphinite Ligands
Authors: Guiu Ester , Muñoz Bianca , Castillón Sergio , Claver Carmen 
Published: January 2003

AbstractIridium complexes incorporating xylose diphosphinite 1 and diphosphite 2, 3 ligands as source of chirality are active catalysts for the hydrogenation of imines providing moderate ee. The enantioselectivity depends on the fine tuning of the structural parameters of the ligand and on the effect of additives.
Dramatic Pressure Effects on the Selectivity of the Aqueous/Organic Biphasic Hydrogenation of trans‐Cinnamaldehyde Catalyzed by Water‐Soluble Ru(II)‐Tertiary Phosphane Complexes
Authors: Papp Gábor , Elek János , Nádasdi Levente , Laurenczy Gábor , Joó Ferenc 
Published: January 2003

AbstractIn a water/chlorobenzene biphasic reaction, the hydrogenation of trans‐cinnamaldehyde, catalyzed by water‐soluble Ru(II)‐phosphane complexes at pH 3.04 (phosphate buffer), produces a 61:39 mixture of cinnamyl alcohol and dihydrocinnamaldehyde at 1 bar H2; however, the selectivity is increased to 93:7 by increasing the hydrogen pressure to 8 bar.
Amphiphilic Resin‐Supported Ruthenium(II) Complexes as Recyclable Catalysts for the Hydrogenation of Supercritical Carbon Dioxide
Authors: Kayaki Yoshihito , Shimokawatoko Yoshiki , Ikariya Takao 
Published: January 2003

AbstractDichloro‐ and dihydridoruthenium(II) catalysts attached to an amphiphilic resin (PS−PEG) were prepared and tested for hydrogenation of supercritical carbon dioxide (scCO2) in the presence of dimethylamine leading to N,N‐dimethylformamide (DMF). The supported catalysts were successfully recyclable with only moderate loss of activity.
Synthesis and Application of Chiral Phospholane Ligands Bearing a Sterically and Electrically Adjustable Moiety
Authors: Matsumura Kazuhiko , Shimizu Hideo , Saito Takao , Kumobayashi Hidenori 
Published: January 2003

AbstractA series of C1‐symmetric phosphine‐phospholane ligands, 1‐(disubstituted phosphino)‐2‐(phospholano)benzenes (5), which are called UCAPs, with an achiral phosphino group and a chiral phospholane which can be sterically and electrically adjustable, has been designed and synthesized. In the asymmetric hydrogenation of (Z)‐N‐benzoyl‐1‐phenylpropenamine (3), the stereorecognition abilities of the 5d−e–Rh catalysts which have a bulkier aryl substituent on the achiral phosphorus are superior to that observed with the DuPHOS‐Rh catalyst. The effects of varying substituents on the achiral phosphorus atom are discussed.