bluuebunny/crossref_metadata_2025_split huggingface dataset:
HHV‐8 infection: a model for reactivation and transmission
Authors: Corey Lawrence , Brodie Scott , Huang Meei‐Li , Koelle David M. , Wald Anna 
Published: August 2002

AbstractThe rapid pace of knowledge about HHV‐8 since its discovery has been one of the most exciting aspects of medical virology in the last decade. As outlined in this review, the discovery by Drs Chang and Moore of this virus has opened up a broad field of biology with interesting contrasts between current epidemiological data for Kaposi's sarcoma and the cell biology of this gamma herpesvirus. In particular, we summarise the paucity of virological data supporting genital sites of replication and emphasise detection of HHV‐8 in the oropharynx. Hopefully continued study will address many of the critical questions that exist today regarding how this infection is transmitted and acquired. Copyright © 2001 John Wiley & Sons, Ltd.
Functional balance between haemagglutinin and neuraminidase in influenza virus infections
Authors: Wagner Ralf , Matrosovich Mikhail , Klenk Hans‐Dieter 
Published: August 2002

AbstractInfluenza A and B viruses carry two surface glycoproteins, the haemagglutinin (HA) and the neuraminidase (NA). Both proteins have been found to recognise the same host cell molecule, sialic acid. HA binds to sialic acid‐containing receptors on target cells to initiate virus infection, whereas NA cleaves sialic acids from cellular receptors and extracellular inhibitors to facilitate progeny virus release and to promote the spread of the infection to neighbouring cells. Numerous studies performed recently have revealed that an optimal interplay between these receptor‐binding and receptor‐destroying activities of the surface glycoproteins is required for efficient virus replication. An existing balance between the antagonistic HA and NA functions of individual viruses can be disturbed by various events, such as reassortment, virus transmission to a new host, or therapeutic inhibition of neuraminidase. The resulting decrease in the viral replicative fitness is usually overcome by restoration of the functional balance due to compensatory mutations in HA, NA or both proteins. Copyright © 2002 John Wiley & Sons, Ltd.
Practical stabilization of exponentially unstable linear systems subject to actuator saturation nonlinearity and disturbance
Authors: Hu Tingshu , Lin Zongli 
Published: August 2002

AbstractThis paper investigates the problem of practical stabilization for linear systems subject to actuator saturation and input additive disturbance. Attention is restricted to systems with two anti‐stable modes. For such a system, a family of linear feedback laws is constructed that achieves semi‐global practical stabilization on the asymptotically null controllable region. This is in the sense that, for any setχ0in the interior of the asymptotically null controllable region, any (arbitrarily small) setχ∞containing the origin in its interior, and any (arbitrarily large) bound on the disturbance, there is a feedback law from the family such that any trajectory of the closed‐loop system enters and remains in the setχ∞in a finite time as long as it starts from the setχ0. In proving the main results, the continuity and monotonicity of the domain of attraction for a class of second‐order systems are revealed. Copyright © 2001 John Wiley & Sons, Ltd.
Multiple model adaptive control. Part 2: switching
Authors: Hespanha João , Liberzon Daniel , Stephen Morse A. , Anderson Brian D. O. , Brinsmead Thomas S. , De Bruyne Franky 
Published: August 2002

AbstractThis paper addresses the problem of controlling a continuous‐time linear system with large modelling errors. We employ an adaptive control algorithm consisting of a family of linear candidate controllers supervised by a high‐level switching logic. Methods for constructing such controller families have been discussed in the recent paper by the authors. The present paper concentrates on the switching task in a multiple model context. We describe and compare two different switching logics, and in each case study the behaviour of the resulting closed‐loop hybrid system. Copyright © 2001 John Wiley & Sons, Ltd.
An algorithm for the structural analysis of state space: synthesis of nonlinear observers
Authors: López‐Moralès Virgilio , Plestan Franck , Glumineau Alain 
Published: August 2002

AbstractThe problem addressed is the linearization of multi‐input multi‐output (MIMO) nonlinear systems by a generalized state coordinates transformation and generalized input–output injection, in order to design an observer. This observer will have linear error dynamics. The goal is to bring together two observers design approaches: a structural one and a numerical one. Necessary and sufficient conditions for the existence of a linearizing generalized state transformation are obtained by an algebraic way and without computing the input–output differential equations. The main result tests integrability conditions of differential one‐forms derived from the state space representation and is applicable to a large subclass of nonlinear systems. Copyright © 2001 John Wiley & Sons, Ltd.
Some conditions which make the constantly scaledH∞control synthesis problems convex
Authors: Asai Toru , Hara Shinji 
Published: August 2002

AbstractIn this paper, we present some computationally tractable conditions which make the constantly scaledH∞control synthesis problem convex. If one of the conditions proposed in this paper holds, the constantly scaledH∞control synthesis problem can be solved efficiently as an LMI problem. The results presented here include the existing results such as the state feedback and the full information problems as special cases. In addition, the results are generalized to the case that some of state variables are exactly available. Owing to this generalization, a larger class of problems can be reduced to convex problems, while reduced order controllers can be obtained. Copyright © 2001 John Wiley & Sons, Ltd.
A subspace approach to balanced truncation for model reduction of nonlinear control systems
Authors: Lall Sanjay , Marsden Jerrold E. , Glavaški Sonja 
Published: August 2002

AbstractIn this paper, we introduce a new method of model reduction for nonlinear control systems. Our approach is to construct an approximately balanced realization. The method requires only standard matrix computations, and we show that when it is applied to linear systems it results in the usual balanced truncation. For nonlinear systems, the method makes use of data from either simulation or experiment to identify the dynamics relevant to the input–output map of the system. An important feature of this approach is that the resulting reduced‐order model is nonlinear, and has inputs and outputs suitable for control. We perform an example reduction for a nonlinear mechanical system. Copyright © 2002 John Wiley & Sons, Ltd.
Robust reinforcement learning control with static and dynamic stability
Authors: Kretchmar R. Matthew , Young Peter M. , Anderson Charles W. , Hittle Douglas C. , Anderson Michael L. , Delnero Christopher C. 
Published: August 2002

AbstractRobust control theory is used to design stable controllers in the presence of uncertainties. This provides powerful closed‐loop robustness guarantees, but can result in controllers that are conservative with regard to performance. Here we present an approach to learning a better controller through observing actual controlled behaviour. A neural network is placed in parallel with the robust controller and is trained through reinforcement learning to optimize performance over time. By analysing nonlinear and time‐varying aspects of a neural network via uncertainty models, a robust reinforcement learning procedure results that is guaranteed to remain stable even as the neural network is being trained. The behaviour of this procedure is demonstrated and analysed on two control tasks. Results show that at intermediate stages the system without robust constraints goes through a period of unstable behaviour that is avoided when the robust constraints are included. Copyright © 2001 John Wiley & Sons, Ltd.
A position/force control for a robot finger with soft tip and uncertain kinematics
Authors: Doulgeri Zoe , Arimoto Suguru 
Published: August 2002

AbstractWe consider the position and force regulation problem for a soft tip robot finger in contact with a rigid surface under kinematic and dynamic parametric uncertainties. The reproducing force is assumed to be related to the displacement through a nonlinear function whose characteristics are unknown, but both the actual displacement and force can be directly measured. Kinematic uncertainties concern the rigid surface orientation and the contact point location. Kinematic parameters involved in the contact point location concern the length from the last joint to the contact point and the rest of the link lengths in the general case. An adaptive controller with a composite update parameter law is proposed, and the asymptotic stability of the force and estimated position errors under dynamic and kinematic uncertainties is shown for the planar case. Simulation results for a three‐degrees‐of‐freedom planar robotic finger are presented. © 2002 Wiley Periodicals, Inc.
Controller design for natural and robotic systems with transmission delays
Authors: Kataria Abhay , Özbay Hitay , Hemami Hooshang 
Published: August 2002

AbstractRobust stability and two‐dimensional trajectory following problems are considered forn‐link robotic systems with transmission delays. Such problems appear in telerobotics, where the controller is physically far from the robot, and in neural control of musculo‐skeletal (biological) systems, where muscle actuation and neural sensing are subject to time delays. A typical second‐order nonlinear dynamical model is taken with input and output time delays. In a prior work by the authors, a control strategy was developed for stable movement of the planar linkage system, using the standardQ‐parameterization and solving anH∞control problem to determine the free parameter. In this article, a new control scheme is proposed to eliminate the steady‐state errors seen in the tracking performance of the controller derived in the earlier work. Simulation examples are shown to demonstrate the effectiveness of the proposed control methodology. © 2002 Wiley Periodicals, Inc.
Neural network‐based state prediction for strategy planning of an air hockey robot
Authors: Park Jung Il , Partridge Chad B. , Spong Mark W. 
Published: August 2002

AbstractWe analyze a neural network implementation for puck state prediction in robotic air hockey. Unlike previous prediction schemes which used simple dynamic models and continuously updated an intercept state estimate, the neural network predictor uses a complex function, computed with data acquired from various puck trajectories, and makes a single, timely estimate of the final intercept state. Theoretically, the network can account for the complete dynamics of the table if all important state parameters are included as inputs, an accurate data training set of trajectories is used, and the network has an adequate number of internal nodes. To develop our neural networks, we acquired data from 1500 no‐bounce and 1500 one‐bounce puck trajectories, noting only translational state information. Analysis showed that performance of neural networks designed to predict the results of no‐bounce trajectories was better than the performance of neural networks designed for one‐bounce trajectories. Since our neural network input parameters did not include rotational puck estimates and recent work shows the importance of spin in impact analysis, we infer that adding a spin input to the neural network will increase the effectiveness of state estimates for the one‐bounce case. © 2001 John Wiley & Sons, Inc.
Position and force tracking of a two‐manipulator system manipulating a flexible beam
Authors: Sun Dong , Liu Yun‐Hui 
Published: August 2002

AbstractThis article discusses the issue of hybrid position and force control of a two‐manipulator system manipulating a flexible beam in trajectory tracking. Unlike our previous approach of set‐point position control in the trajectory tracking, the system coordinates are hard to be regulated to the desired states with nonzero tracking velocities under continuous feedback control. In this study, we design a hybrid position and force tracking controller while using saturation control to compensate for the effect of beam vibration dynamics on the tracking performance. All parameters and states used in the controller are readily available so that the proposed method is feasible to implement. Under the proposed controller, the tracking error asymptotically converges to a predetermined boundary. Simulation results demonstrate the validity of the proposed approach. © 2001 John Wiley & Sons, Inc.
Robust force control of a flexible arm with a nonsymmetric rigid tip body
Authors: Morita Yoshifumi , Kobayashi Yukihiro , Kando Hisashi , Matsuno Fumitoshi , Kanzawa Takao , Ukai Hiroyuki 
Published: August 2002

AbstractIn this article, we discuss modeling and robust control of bending and torsional vibrations and contact force of a flexible arm with a nonsymmetric rigid tip body. By using Hamilton's principle and the Lagrange multiplier method, dynamic equations of the constrained flexible arm are derived. Since the flexible arm has the nonsymmetric tip body, the bending and torsional vibrations are coupled. As the obtained boundary conditions of the distributed parameter system are nonhomogeneous, we introduce a change of variables to derive homogeneous boundary conditions. By using the eigenvalues and the correpsonding eigenfunctions related to the distributed parameter system, we derive a finite‐dimensional modal model. To compensate for the spillover instability, we construct robust controllers of an optimal controller with a low‐pass property and anH∞controller. Some experiments have been carried out to show the effectiveness of the proposed robust controllers. © 2001 John Wiley & Sons, Inc.
A real‐coded genetic optimal kinematic design of a Stewart fine tuning platform for a large radio telescope
Authors: Su Y. X. , Duan B. Y. , Peng B. , Nan R. D. 
Published: August 2002

AbstractA real‐coded genetic design methodology for an optimal kinematic Stewart platform is presented in this article. The Jacobian matrix connecting the dexterity performance of the parallel platform is first deduced, and then the condition number of Jacobian matrix is employed as the objective function to implement the optimal kinematic design of Stewart fine tuning platform for a large spherical radio telescope. A niched‐penalty approach is used to transform this optimal kinematic design problem to an unconstrained one, and a niching technique and the dynamic mutation operator are applied. A kinematic accuracy comparison of the genetically designed Stewart fine tuning platform with the quasi‐Newtonian designed platform is made. The comparison results have shown that the kinematic accuracy of the genetically designed Stewart fine tuning platform has a much higher accuracy and compact structure than that of the quasi‐Newtonian designed platform, which guarantees the implementation of high accuracy requirement of trajectory tracking and reduces the disturbance of random wind for large radio telescopes. © 2001 John Wiley & Sons, Inc.
Design and analysis of some nonanthropomorphic, biologically inspired robots: An overview
Authors: Chirikjian Gregory S. 
Published: August 2002

AbstractIn this paper, two kinds of biologically inspired robots under investigation at Johns Hopkins University are reviewed. While these designs are reminiscent of designs in nature, they are, however, not anthropomorphic. Rather, they are zoomorphic in macroscopic structure. These two kinds of robots are snakelike “hyper‐redundant” manipulators, and amoeboid “metamorphic” robots. In addition to issues in the design of the robots, issues in the dynamics and motion planning of these devices are reviewed. © 2001 John Wiley & Sons, Inc.
Optimal robot motions for physical criteria
Authors: Bobrow J. E. , Martin B. , Sohl G. , Wang E. C. , Park F. C. , Kim Junggon 
Published: August 2002

AbstractThis paper presents an optimization‐based framework for emulating the low‐level capabilities of human motor coordination and learning. Our approach rests on the observation that in most biological motor learning scenarios some form of optimization with respect to a physical criterion is taking place. By appealing to techniques from the theory of Lie groups, we are able to formulate the equations of motion of complex multibody systems in such a way that the resulting optimization problems can be solved reliably and efficiently—the key lies in the ability to compute exact analytic gradients of the objective function without resorting to numerical approximations. The methodology is illustrated via a wide range of optimized, “natural” motions for robots performing various human‐like tasks—for example, power lifting, diving, and gymnastics. © 2001 John Wiley & Sons, Inc.
New and faster filters for multiple approximate string matching
Authors: Baeza‐Yates Ricardo , Navarro Gonzalo 
Published: August 2002

AbstractWe present three new algorithms for on‐line multiple string matching allowing errors. These are extensions of previous algorithms that search for a single pattern. The average running time achieved is in all cases linear in the text size for moderate error level, pattern length, and number of patterns. They adapt (with higher costs) to the other cases. However, the algorithms differ in speed and thresholds of usefulness. We theoretically analyze when each algorithm should be used, and show their performance experimentally. The only previous solution for this problem allows only one error. Our algorithms are the first to allow more errors, and are faster than previous work for a moderate number of patterns (e.g. less than 50–100 on English text, depending on the pattern length). © 2002 John Wiley & Sons, Inc. Random Struct. Alg., 20, 23–49, 2002
High elevation angle satellite‐to‐earth 12 GHz propagation measurements in the tropics
Authors: Pan Qingwei , Bryant Geoff H. , McMahon John , Allnutt Jeremy E. , Haidara Fatim 
Published: August 2002

AbstractA simple, low‐cost propagation terminal for measuring path attenuation and site diversity, using satellite transmissions at 12 GHz, is described. The novelty of this system is the use of a standard domestic satellite low‐noise block (LNB) front‐end connected directly to a spectrum analyser in place of an expensive beacon receiver. A description of the equipment, an analysis of relevant system parameters, and a discussion of the environmental conditions are presented. The method used to obtain a clear‐sky baseline reference and a description of the channel signal processing are given. Analysis of the rainfall rate and attenuation exceedances statistics has led to the proposal of a new model to derive the effective rain‐cell diameters and effective rain‐column heights in tropical areas for attenuation predictions in satellite communication link budget calculations. Site‐diversity statistics are also examined. Though the main site is only 6.5 km inland from the second coastal site, there are marked differences in their rain‐cell characteristics. The significance of volume saturation of rain cells on modelling, the operating margins of the measuring system, and the relevance of the site‐diversity data to enhancing the understanding of the proposed volume saturation model are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of handover characteristics in shadowed LEO satellite communication networks
Authors: Kwon Young Hoon , Sung Dan Keun 
Published: August 2002

AbstractIn the near future, low earth orbit (LEO) satellite communication networks will partially substitute the fixed terrestrial multimedia networks especially in sparsely populated areas. Unlike fixed terrestrial networks, ongoing calls may be dropped if satellite channels are shadowed. Therefore, in most LEO satellite communication networks more than one satellite needs to be simultaneously visible in order to hand over a call to an unshadowed satellite when the communicating satellite is shadowed. In this paper, handover characteristics for fixed terminals (FTs) in LEO satellite communication networks are analysed. The probability distribution of multiple satellite visibility is analytically obtained and the shadowing process of satelites for FTs are modelled. Using the proposed analysis model, shadowing effects on the traffic performance are evaluated in terms of the number of intersatellite and interbeam handovers during a call. Copyright © 2001 John Wiley & Sons, Ltd.
Tangled up in views: Beliefs in the nature of science and responses to socioscientific dilemmas
Authors: Zeidler Dana L. , Walker Kimberly A. , Ackett Wayne A. , Simmons Michael L. 
Published: August 2002

AbstractThe purpose of this study was to investigate the relationships between students' conceptions of the nature of science and their reactions to evidence that challenged their beliefs about socioscientific issues. This study involved 41 pairs of students representing “critical cases” of contrasting ethical viewpoints. These 82 students were identified from a larger sample of 248 students from 9th and 10th grade general science classes, 11th and 12th grade honors biology, honors science, and physics classes, and upper‐level college preservice science education classes. Students responded to questions aimed at revealing their epistemological views of the nature of science and their belief convictions on a selected socioscientific issue. The smaller subset of students was selected based on varying degrees of belief convictions about the socioscientific issues and the selected students were then paired to discuss their reasoning related to the issue while being exposed to anomalous data and information from each other and in response to epistemological probes of an interviewer. Taxonomic categories of students' conceptions of the nature of science were derived from the researchers' analysis of student responses to interviews and questionnaires. In some instances, students' conceptions of the nature of science were reflected in their reasoning on a moral and ethical issue. This study stimulated students to reflect on their own beliefs and defend their opinions. The findings suggest that the reactions of students to anomalous socioscientific data are varied and complex, with notable differences in the reasoning processes of high school students compared to college students. A deeper understanding of how students reason about the moral and ethical context of controversial socioscientific issues will allow science educators to incorporate teaching strategies aimed at developing students' reasoning skills in these crucial areas. © 2002 Wiley Periodicals, Inc. Sci Ed 86:343–367, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/sce.10025
Similarity and difference: Student cooperation in Taiwanese and Australian science classrooms
Authors: Wallace John , Chou Ching‐Yang 
Published: August 2002

AbstractIn this study, we examine the way in which students cooperate in Taiwanese and Australian science classrooms. We adopt the position that student cooperation is best understood by examining the patterns of variation within and between countries rather than trying to describe similarities and differences in essential terms. A critical analysis of large‐scale learning environment questionnaire data combined with in‐depth interview and observational data leads to several findings about the nature of student cooperation in the two countries. We conclude that students from Taiwan and Australia have a range of understandings and interpretations about what it means to cooperate in science classrooms. There are complex connections between cooperative behavior, student academic ability, sex, and nationality, which are best understood in socio‐cultural terms. © 2001 John Wiley & Sons, Inc. Sci Ed 85:694–711, 2001.