bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of amino acids as formamidene butyl esters by electrospray ionization tandem mass spectrometry
Authors: Johnson David W. 
Published: August 2002

AbstractAmino acid formamidene butyl esters are optimally prepared by heating amino acids with dimethylformamide dimethylacetal (DMF‐DMA) for 2 minutes at 65 °C and then with n‐butanol/hydrogen chloride for 15 minutes at 65 °C. The formamidene butyl esters of simple α‐amino acids and β‐amino acids afford between 1.1 and 20 times the signal intensity of the corresponding butyl esters during electrospray ionization tandem mass spectral analysis. Complex α‐amino acids, such as ornithine, arginine and citrulline, and γ‐amino acids are better analyzed as butyl esters. Secondary α‐amino acids, such as proline and sarcosine, give a mixture of two iminium salts with the DMF‐DMA derivatization method. A derivative incorporating two molecules of the amino acid predominates at higher derivatization temperatures. Contrary to a previous report, N‐formylamino acids were not detected. The presence of secondary amino acids in amino acid mixtures, derivatized as formamidene butyl esters, affords derivatives that incorporate two different amino acids. The new formamidene butylation method is unlikely to replace the butylation procedure used by neonatal blood spot screening programs for amino acid disorders, since a much poorer response was obtained with formamidene butyl esters of arginine and citrulline, important in the diagnosis of arginase deficiency and citrullinaemia. Copyright © 2001 John Wiley & Sons, Ltd.
India Ink staining after sodium dodecyl sulfate polyacrylamide gel electrophoresis and in conjunction with Western blots for peptide mapping by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Klarskov Klaus , Naylor Stephen 
Published: August 2002

AbstractWe present an approach that allows matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometric (MALDI‐TOFMS) peptide mapping of proteins separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) and electroblotted onto nitrocellulose (NC). After blocking the nitrocellulose membrane with polyvinylpyrrolidone‐40 the immobilized proteins are visualized using India Ink staining which allows the detection of low nanogram amounts of protein. The utilization of a low concentration of Tween 20 (0.05%) in the India Ink staining solution does not negatively impair the quality of the mass spectra. Due to the virtual nondestructive nature of the stain proteolytic peptides could be recovered from the NC membrane. Taking into account minor precautions during the sample manipulation and concentration and by loading the sample onto a pre‐crystallized matrix layer, high quality mass spectral data were obtained on <100 femtomoles of protein loaded onto the gel. Finally, the use of India Ink in conjunction with Western blot analysis is also demonstrated. A rat plasma protein, characterized by Western blot as a covalently modified protein‐drug compound, was subjected to peptide mapping and post source decay (PSD) sequencing of peptides. The zomepirac‐modified protein was identified as the alpha‐subunit of fibrinogen. Copyright © 2001 John Wiley & Sons, Ltd.
Linear QFT control of a highly nonlinear multi‐machine power system
Authors: Kelemen Matei , Akhrif Ouassima 
Published: August 2002

AbstractA quantitative feedback theory (QFT) method of Horowitz, treating nonlinearities as equivalent disturbances, is applied to the linear control of a multi‐machine power system. This system has a smooth nonlinear dynamics so the original approach was simplified. From the design point of view good results were obtained with simple controllers (automatic voltage regulator, speed governor, power system stabilizer) when the power system was affected by large load variations and short circuits. To reduce significantly the steady state errors which appeared, a novel rotor speed error amplification scheme was employed. This increased the autonomy of the controlled power system to combat big distortions from normal operating conditions. Copyright © 2001 John Wiley & Sons, Ltd.
Survey of quantitative feedback theory (QFT)
Authors: Horowitz Isaac 
Published: August 2002

AbstractQFT is an engineering design theory devoted to the practical design of feedback control systems. The foundation of QFT is that feedback is needed in control only when plant (P), parameter and/or disturbance (D) uncertainties (sets 𝒫={P}, 𝒟={D}) exceed the acceptable (A) system performance uncertainty (set 𝒜={A}). The principal properties of QFT are as follows. (1) The amount of feedback needed is tuned to the (𝒫, 𝒟, 𝒜) sets. If 𝒜 ‘exceeds’ (𝒫, 𝒟), feedback is not needed at all. (2) The simplest modelling is used: (a) command, disturbance and sensor noise inputs, and (b) the available sensing points and the defined outputs. No special controllability test is needed in either linear or non‐linear plants. It is inherent in the design procedure. There is no observability problem because uncertainty is included. The number of independent sensors determines the number of independent loop transmissions (Li), the functions which provide the benefits of feedback. (3) The simplest mathematical tools have been found most use ful—primarily frequency response. The uncertainties are expressed as sets in the complex plane. The need for the larger 𝒫, 𝒟 sets to be squeezed into the smaller 𝒜 set results in bounds on theLi(jω) in the complex plane. In the more complex systems a key problem is the division of the ‘feedback burden’ among the availableLi(jω). Point‐by‐point frequency synthesis tremendously simplifies this problem. This is also true for highly uncertain non‐linear and time‐varying plants which are converted into rigorously equivalent linear time invariant plant sets and/or disturbance sets with respect to the acceptable output set 𝒜. Fixed point theory justifies the equivalence. (4) Design trade‐offs are highly transparent in the frequency domain: between design complexity and cost of feedback (primarily bandwidth), sensor noise levels, plant saturation levels, number of sensors needed, relative sizes of 𝒫, 𝒜 and cost of feedback. The designer sees the trade‐offs between these factors as he proceeds and can decide according to their relative importance in his particular situation.QFT design techniques with these properties have been developed step by step for: (i) highly uncertain linear time invariant (LTI) SISO single‐ and multiple‐loop systems, MIMO single‐loop matrix and multiple‐loop matrix systems; and (ii) non‐linear and time‐varying SISO and MIMO plants, and to a more limited extent for plants with distributed control inputs and sensors. QFT has also been developed for single‐ and multiple‐loop dithered non‐linear (adaptive) systems with LTI plants, and for a special class (FORE) of non‐linear compensation. New techniques have been found for handling non‐minimum‐phase (NMP) MIMO plants, plants with both zeros and poles in the right half‐plane and LTI plants with incidental hard non‐linearities such as saturation.
Developing a fault tolerant power‐train control system by integrating design of control and diagnostics
Authors: Kim Yong‐Wha , Rizzoni Giorgio , Utkin Vadim I. 
Published: August 2002

AbstractFault detection, isolation and fault tolerant control are investigated for an spark ignition engine. Fault tolerant control refers to a strategy in which the desired stability and robustness of the control system are guaranteed in the presence of faults. In an attempt to realize fault tolerant control, a methodology for integrated design of control and fault diagnostics is proposed. Specifically, the integrated design of control and diagnostics is achieved by combining the integral sliding mode control methodology and observers with hypothesis testing. Information obtained from integral sliding mode control and from observers with hypothesis testing is utilized so that a fault can be detected, isolated and compensated. As an application example, the air and fuel dynamics of an IC engine are considered. A mean value engine model is developed and implemented in Simulink®. The air and fuel dynamics of the engine are identified using experimental data. The proposed algorithm for integration of control and diagnostics is then validated using the identified engine model. Copyright © 2001 John Wiley & Sons, Ltd.
Feasibility in predictive control of constrained linear systems: the output feedback case
Authors: Chisci Luigi , Zappa Giovanni 
Published: August 2002

AbstractThis paper addresses model‐based predictive regulation for a linear discrete‐time system in the presence of unknown but bounded disturbances, partial state information and state/control constraints. The proposed nonlinear dynamic compensator uses a set‐valued estimator, which recursively updates the membership set of the plant state, along with a receding‐horizon regulator which selects on‐line the control variable depending upon the current state membership set. It is shown that the overall scheme preserves feasibility if this is assumed from the outset, and hence guarantees closed‐loop stability and constraint fulfilment. These properties rely on exact set‐membership estimation. A simple approximation scheme which avoids set‐membership estimation but preserves stability is also proposed and the relative performance/complexity tradeoffs are discussed. Simulation results demonstrate the effectiveness of the proposed method. Copyright © 2002 John Wiley & Sons, Ltd.
IQC robustness analysis for time‐delay systems
Authors: Jun Myungsoo , Safonov Michael G. 
Published: August 2002

AbstractStability robustness of systems with uncertain time delays is considered. A new delay‐dependent state‐space stability criterion is formulated in the form of an easily checked LMI condition. Two applications of the main result are presented, one with only time‐delay uncertainty and one with both delay and parametric uncertainty. Copyright © 2001 John Wiley & Sons, Ltd.
Active force closure for multiple objects
Authors: Harada Kensuke , Kaneko Makoto , Tsuji Toshio 
Published: August 2002

AbstractThis article discusses active force closure (AFC) for the manipulation of multiple objects. AFC for multiple objects is defined in such a way that the finger can generate an arbitrary acceleration onto a certain point of multiple objects. We define two kinds of AFC: in the first, an arbitrary acceleration can be generated onto each of the objects; in the second, an arbitrary acceleration can be generated onto the center of mass of multiple objects without changing the relative position of the objects. We show that the grasped object cannot always be manipulated arbitrarily even if the first kind of AFC is satisfied. We also show that the grasped objects are manipulated like a single rigid body if the second kind of AFC is satisfied. To explain these features of AFCs, numerical examples for the grasp of three objects are shown. © 2002 Wiley Periodicals, Inc.
Realization of those elastic behaviors that have compliant axes in compact elastic mechanisms
Authors: Huang Shuguang , Schimmels Joseph M. 
Published: August 2002

AbstractIn this article, we address the synthesis and realization of a subset of spatial elastic behaviors, those with compliant axes, in compact parallel mechanisms. Using the procedures developed, a geometric description of the layout of a compact mechanism of springs connected in parallel is obtained. In each of these mechanisms, each spring axis is restricted to intersect a single point in space. The variation in the orientation of the intersecting spring axes is also restricted. The degree of restriction in axis orientation is determined by the number of “compliant axes” associated with the specified elastic behavior. Also, as part of this work, a physical appreciation of the different classes of stiffnesses that have compliant axes is identified and interpreted in different types of concurrent parallel mechanisms. © 2002 Wiley Periodicals, Inc.
Stiffness characteristics and kinematics analysis of two‐link elastic underactuated manipulators
Authors: Dai Jian S. , Zhao Tie Shi 
Published: August 2002

AbstractThis article investigates the stiffness characteristics of two‐link underactuated manipulators, examines the effect on the torque resulting in the passive joint, and develops a stiffness model in analysing the behaviors of the manipulators. The kinematic analysis leads to the trajectory of the end‐effector, which is associated with the stiffness coupled between the active and passive joints and with the constraint forces, and the kinematic coupling is shown in the angular displacement and in the resulting torque. The stiffness characteristics are illustrated in the directional stiffness mapping, which gives a quantitative measure of stiffness with respect to displacement direction. © 2002 Wiley Periodicals, Inc.
Locomotion characteristics of an SMA‐actuated micro robot simulating a medicinal leech in a pipeline
Authors: Liu Fang‐Hu , Ma Pei‐Sun , Chen Jian‐Ping , Zhu Jie , Yao Qin 
Published: August 2002

AbstractResearch into the locomotion principle of a new micro peristaltic robot simulating a medicinal leech in a pipeline, and a subsequent kinematic model, inform this article. The effects of structure on robot performance are analyzed; also presented is the basis for the robot's redesign, parameterized design, and optimal design. © 2002 Wiley Periodicals, Inc.
A tetrahedron approach for a unique closed‐form solution of the forward kinematics of six‐dof parallel mechanisms with multiconnected joints
Authors: Song Se‐Kyong , Kwon Dong‐Soo 
Published: August 2002

AbstractThis article presents a new formulation approach that uses tetrahedral geometry to determine a unique closed‐form solution of the forward kinematics of six‐dof parallel mechanisms with multiconnected joints. For six‐dof parallel mechanisms that have been known to have eight solutions, the proposed formulation, called theTetrahedron Approach, can find a unique closed‐form solution of the forward kinematics using the three proposed Tetrahedron properties. While previous methods to solve the forward kinematics involve complicated algebraic manipulation of the matrix elements of the orientation of the moving platform, or closed‐loop constraint equations between the moving and the base platforms, the Tetrahedron Approach piles up tetrahedrons sequentially to directly solve the forward kinematics. Hence, it allows significant abbreviation in the formulation and provides an easier systematic way of obtaining a unique closed‐form solution. © 2002 Wiley Periodicals, Inc.
Planning and controlling cooperating robots through distributed impedance
Authors: Szewczyk Jérôme , Plumet Frédéric , Bidaud Philippe 
Published: August 2002

AbstractThis article presents distributed impedance as a new approach for multiple robot system control. In this approach, each cooperating manipulator is controlled by an independent impedance controller. In addition, along selected degrees of freedom, force control is achieved through an external loop, to improve control of the object's internal loading. Extensive stability analysis is performed, based on a realistic model that includes robot impedance and object dynamics. Experiments are performed using two cooperating industrial robots holding an object through point contacts. Force and position control actions are suitably dispatched to achieve both internal loading control and object position control. Individual impedance parameters are specified according to the theoritical stability criterion. The performance of the system is demonstrated for transportation and contact tasks. © 2002 Wiley Periodicals, Inc.
Fusing force and vision feedback for manipulating deformable objects
Authors: Luo Yanhong , Nelson Bradley J. 
Published: August 2002

AbstractThis article describes a framework that fuses vision and force feedback for the control of highly deformable objects. Deformable active contours, or snakes, are used to visually observe changes in object shape over time. Finite‐element models of object deformations are used with force feedback to predict expected visually observed deformations. Our approach improves the performance of large, complex deformable contour tracking over traditional computer vision tracking techniques. This same approach of combining deformable active contours with finite‐element material models is modified so that a vision sensor, i.e., a charge‐coupled device (CCD) camera, can be used as a force sensor. By visually tracking changes in contours on the object, material deflections can be transformed into applied stress estimates through finite element modeling. Therefore, internal object stresses due to object manipulation can be visually observed and controlled, thus creating a framework for deformable object manipulation. A pinhole camera model is used to accomplish vision and force sensor feedback assimilation from these two sensing modalities during manipulation. © 2001 John Wiley & Sons, Inc.
Point‐to‐point and multi‐goal path planning for industrial robots
Authors: Wurll Christian , Henrich Dominik 
Published: August 2002

AbstractThis article presents contributions in the field of path planning for industrial robots with 6 degrees of freedom. This work presents the results of our research in the last 4 years at the Institute for Process Control and Robotics at the University of Karlsruhe. The path planning approach we present works in an implicit and discretized C‐space. Collisions are detected in the Cartesian workspace by a hierarchical distance computation. The method is based on the A* search algorithm and needs no essential off‐line computation. A new optimal discretization method leads to smaller search spaces, thus speeding up the planning. For a further acceleration, the search was parallelized. With a static load distribution good speedups can be achieved. By extending the algorithm to a bidirectional search, the planner is able to automatically select the easier search direction. The new dynamic switching of start and goal leads finally to the multi‐goal path planning, which is able to compute a collision‐free path between a set of goal poses (e.g., spot welding points) while minimizing the total path length. © 2001 John Wiley & Sons, Inc.
Humanoids and personal robots: Design and experiments
Authors: Dario Paolo , Guglielmelli Eugenio , Laschi Cecilia 
Published: August 2002

AbstractThis paper addresses the field of humanoid and personal robotics—its objectives, motivations, and technical problems. The approach described in the paper is based on the analysis of humanoid and personal robots as an evolution from industrial to advanced and service robotics driven by the need for helpful machines, as well as a synthesis of the dream of replicating humans.The first part of the paper describes the development of anthropomorphic components for humanoid robots, with particular regard to anthropomorphic sensors for vision and touch, an eight‐d.o.f. arm, a three‐fingered hand with sensorized fingertips, and control schemes for grasping. Then, the authors propose a user‐oriented design methodology for personal robots, and describe their experience in the design, development, and validation of a real personal robot composed of a mobile unit integrating some of the anthropomorphic components introduced previously and aimed at operating in a distributed working environment.Based on the analysis of experimental results, the authors conclude that humanoid robotics is a tremendous and attractive technical and scientific challenge for robotics research. The real utility of humanoids has still to be demonstrated, but personal assistance can be envisaged as a promising application domain. Personal robotics also poses difficult technical problems, especially related to the need for achieving adequate safety, proper human–robot interaction, useful performance, and affordable cost. When these problems are solved, personal robots will have an excellent chance for significant application opportunities, especially if integrated into future home automation systems, and if supported by the availability of humanoid robots. © 2001 John Wiley & Sons, Inc.
A unified framework for obtaining improved approximation algorithms for maximum graph bisection problems
Authors: Halperin Eran , Zwick Uri 
Published: August 2002

AbstractWe obtain improved semidefinite programming based approximation algorithms forallthe natural maximum bisection problems of graphs. Among the problems considered are: MAX$n\over 2$‐BISECTION—partition the vertices of the graph into two sets of equal size such that the total weight of edges connecting vertices from different sides is maximized; MAX$n\over 2$‐VERTEX‐COVER—find a set containing half of the vertices such that the total weight of edges touching this set is maximized; MAX$n\over 2$‐DENSE‐SUBGRAPH—find a set containing half of the vertices such that the total weight of edges connecting two vertices from this set is maximized; and MAX$n\over 2$UNCUT—partition the vertices into two sets of equal size such that the total weight of edges that donotcross the cut is maximized. We also consider the directed versions of these problems, such as MAX$n\over 2$‐DIRECTED‐BISECTION and MAX$n\over 2$‐DIRECTED‐UNCUT. These results can be used to obtain improved approximation algorithms for the unbalanced versions of the partition problems mentioned above, where we want to partition the graph into two sets of size$k$and$n - k$, where$k$is not necessarily$n\over 2$. Our results improve, extend and unify results of Frieze and Jerrum, Feige and Langberg, Ye, and others. All these results may be viewed as extensions of the MAX CUT algorithm of Goemans and Williamson, and the MAX 2‐SAT and MAX DI‐CUT algorithms of Feige and Goemans. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 20:382–402, 2002
Providing multimedia communications services from high altitude platforms
Authors: Grace D. , Daly N. E. , Tozer T. C. , Burr A. G. , Pearce D. A. J. 
Published: August 2002

AbstractSystem level design considerations for high altitude platforms operating in the mm‐wave bands are examined. Propagation effects in these bands are outlined, followed by a brief introduction to different platform scenarios. Ground‐based and platform‐based fixed wireless access scenarios are considered, and it is shown that using a platform, a single base station can supply a much larger coverage area than a terrestrial base station. The effects on performance of platform displacement from its desired location with both fixed and steerable antennas are also examined. It is shown that steerable antennas are of most use when fixed stations are immediately below the platform, with no benefit for fixed stations on the edge of coverage. The bandwidths required to serve several traffic distributions (suburbs and city centre based) are evaluated using the Shannon equation. It is shown that capacity can be constrained when users are located in the city centres, despite longer line of sight paths to users out in the suburbs. The effects of temporal changes in the spatial traffic distribution are investigated. It is shown that bandwith requirements can be reduced if the platform moves to track these changes. Copyright © 2001 John Wiley & Sons, Ltd.