bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic control of a SI engine with variable intake valve timing
Authors: Kang Jun‐Mo , Grizzle J.W. 
Published: March 2003

AbstractEngines equipped with a means to actuate air flow at the intake valve can achieve superior fuel economy performance in steady state. This paper shows how modern nonlinear design techniques can be used to control such an engine over a wide range of dynamic conditions. The problem is challenging due to the nonlinearities and delays inherent in the engine model, and the constraint on the air flow actuator. The controller is designed on the basis of a mean‐value model, which is derived from a detailed intake stroke model. The control solution has two novel features. Firstly, a recovery scheme for integrator wind‐up due to input constraints is directly integrated into the nonlinear control design. The second novel feature is that the control Lyapunov function methodology is applied to a discrete‐time model. The performance of the controller is evaluated and compared with a conventionally controlled engine through simulation on the detailed engine model. Copyright © 2003 John Wiley & Sons, Ltd.
Current‐mode control of DC–DC power converters: a backstepping approach
Authors: Alvarez‐Ramirez J. , Espinosa‐Pérez G. , Noriega‐Pineda D. 
Published: March 2003

AbstractCurrent‐mode control is a robust industrial DC–DC power converter control scheme that has been successfully tested, is widely accepted, and is commonly implemented with conventional linear P and PI controllers. The need of more systematic designs with enhanced performance has motivated recent studies with linear and nonlinear advanced techniques, but the rigorous understanding and substantiation of the underlying key robust functioning capability are still lacking. In this paper, a constructive control approach is employed to study the current‐mode control problem of a class of DC–DC power converters, yielding a cascade control design methodology with: a robust convergence criterion coupled with a systematic and transparent construction‐tuning procedure, a rationale to explain the robust controller functioning, and a unified framework to interpret and compare the proposed controller with the existing conventional and advanced control designs. The implementation and functioning of the proposed control design is illustrated experimentally with a boost converter. Copyright © 2003 John Wiley & Sons, Ltd.
Sliding mode observers for robust detection and reconstruction of actuator and sensor faults
Authors: Tan Chee Pin , Edwards Christopher 
Published: March 2003

AbstractThis paper describes a method for designing sliding mode observers for detection and reconstruction of actuator and sensor faults, that is robust against system uncertainty. The method uses ℋ︁∞concepts to design the sliding motion so that an upper bound on the effect of the uncertainty on the reconstruction of the faults will be minimized. The design method is first applied to the case of actuator faults, and then by some appropriate filtering, the method is extended to the case of sensor faults. A VTOL aircraft example taken from the fault detection literature is used to demonstrate the method and its effectiveness. Copyright © 2003 John Wiley & Sons, Ltd.
Stability analysis and guaranteed domain of attraction for a class of hybrid systems: an LMI approach
Authors: Bean S. Palomino , Coutinho D.F. , Trofino A. , Cury J.E. R. 
Published: March 2003

AbstractThis paper presents sufficient conditions for the regional stability problem for switched piecewise affine systems, a special class of Hybrid Systems. This class of systems are described by an affine differential equation of the type x˙=A(δ)x+b(δ), where x denotes the continuous state vector and δ is a vector of logical variables that modifies the local model of the system in accordance with the continuous dynamics. Using a Lyapunov function of the type v(x)=x′P(x)x, we present LMI conditions that, when feasible, guarantee local stability of the origin of the switched system. Examples of switched affine systems are used to illustrate the results. Copyright © 2003 John Wiley & Sons, Ltd.
Stabilization of a solid propellant rocket instability by state feedback
Authors: Bošković Dejan M. , Krstić Miroslav 
Published: March 2003

AbstractIn this paper a globally stabilizing feedback boundary control law for an arbitrarily fine discretization of a one‐dimensional nonlinear PDE model of unstable burning in solid propellant rockets is presented. The PDE has a destabilizing boundary condition imposed on one part of the boundary. We discretize the original nonlinear PDE model in space using finite difference approximation and get a high order system of coupled nonlinear ODEs. Then, using backstepping design for parabolic PDEs, properly modified to accommodate the imposed destabilizing nonlinear boundary condition at the burning end, we transform the original system into a target system that is asymptotically stable in l2‐norm with the same type of boundary condition at the burning end, and homogeneous Dirichlet boundary condition at the control end. Copyright © 2003 John Wiley & Sons, Ltd.
Virtual object overlay onto uncalibrated camera images for augmented reality
Authors: Harasaki Shunsuke , Saito Hideo 
Published: March 2003

AbstractWe propose a new registration algorithm for overlaying a virtual object generated in a graphics system onto a real‐world image sequence captured by an uncalibrated camera for augmented reality. In our method, a Projective Grid Space (PGS) is defined by using two base images captured from different positions with uncalibrated cameras. In the PGS, correct perspective views of a virtual object can be registered onto an image sequence captured by an uncalibrated camera in real time. Since our method is based on the projective geometry that is defined by two base images, the registration does not require any markers with known 3D positions, but several (at least eight) image feature points are needed for estimating fundamental matrices of the augmented camera with the base images. Based on this method, we constructed an augmented reality system for an uncalibrated camera without any 3D position information in the real world, which runs nearly at video rate (11 frames per second). Experimental results demonstrate the advantages of this method. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 47–55, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10261
Development of extraction method of kidneys from abdominal CT images using a three‐dimensional deformable model
Authors: Tsagaan Baigalmaa , Shimizu Akinobu , Kobatake Hidefumi , Miyakawa Kunihisa 
Published: March 2003

AbstractThis paper presents a method of extraction of kidneys from abdominal CT images using a three‐dimensional deformable model. In the proposed method, an initial surface model is located in an appropriate position of the image and deformed to fit the target's boundaries. Shape feature is incorporated into the deformable model through energy function as a priori knowledge of the target. Concretely, principal curvatures of the model surface are adopted to characterize the geometrical features of the target and its mean and covariance with the neighboring shape are considered when the deformation is demonstrated. We have applied the proposed method to extract kidneys from three‐dimensional abdominal CT images. The experimental results are presented and the effectiveness of the method is discussed in this paper. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 25–36, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10268
A method of multichannel PID control of two‐degree‐of‐freedom wrist joint movements by functional electrical stimulation
Authors: Watanabe Takashi , Iibuchi Kan , Kurosawa Kenji , Hoshimiya Nozomu 
Published: March 2003

AbstractIn restoring motor functions of paralyzed extremities by functional electrical stimulation (FES), determination of stimulus intensities of many muscles in multichannel control is an ill‐posed problem because of redundancy in the input (stimulus intensity)‐output (joint angle) relationship of the musculoskeletal system. In this paper, we use a multi‐input and multi‐output PID controller and propose a parameter determination method for the controller, which can solve the ill‐posed problem in closed‐loop control. In the parameter determination process, the stimulus intensity‐joint angle characteristics of all muscles controlled were measured first. The elements of the matrix that transforms stimulus intensities into joint angles were determined by linear approximation of the measured characteristics. Then a generalized inverse matrix of the transformation matrix was calculated. The generalized inverse matrix and an expanded CHR method were used to determine the parameters of the PID controller. The PID controller was examined in tracking control on several trajectories of two‐degree‐of‐freedom movement of the wrist joint with neurologically intact subjects. Electrical stimulation was applied to four muscles relating to the wrist joint movements through surface electrodes. The tracking control was achieved generally with good performance under different conditions of the gravitational effect. The new method proposed in this paper was found to provide a solution of the ill‐posed problem. Multichannel closed‐loop FES control of the wrist joint could be realized with this method. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 25–36, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10298
Required quantizing resolution for perceptually linearized medical x‐ray images on display monitor
Authors: Furukawa Isao , Suzuki Junji , Ono Sadayasu 
Published: March 2003

AbstractThis paper theoretically clarifies required quantizing resolution to display digitized x‐ray images on a cathode‐ray‐tube (CRT) monitor provided that the observer not recognize contours that do not exist in original x‐ray film images. Human visual system for luminance difference discrimination is an important factor in determining required quantizing resolution. We therefore carry out an analysis using the Barten model, which provides good fit of many experimental data. First, we clarify the required quantizing resolution for the density input to film and that for the voltage input to a CRT monitor. Then, we present the design results of the look‐up table for perceptually linear transform for a CRT that can reproduce the luminance difference information in film images, and clarify the validity of our theoretical studies. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 14–24, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10301
A line drawing simplification method which retains shape by using the fractal dimension
Authors: Uemura Satoshi , Haseyama Miki , Kitajima Hideo 
Published: March 2003

AbstractThis paper presents a novel method for simplification of line drawings which can retain the shape of a given object. By noting that natural shapes innately possess the property designated self‐similarity, the fractal dimension, one of the characteristics of fractal objects and a measure of complexity, is used as an index. With this index the degree of simplification can be quantified. In order to represent the approximation of a given object, the feature points are extracted by our analysis, whose basic idea was derived from Vector Tracer. Experimental results show the efficiency of our proposed method. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 1–13, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10317
Memory‐based self‐localization using omnidirectional images
Authors: Iwasa Hidehiko , Aihara Nobuhiro , Yokoya Naokazu , Takemura Haruo 
Published: March 2003

AbstractFor a robot, recognizing its location in a real environment is important in terms of visual navigation, etc. This paper proposes a memory‐based self‐localization method based on the use of omnidirectional images. In the proposed method, information that is constant relative to rotation around the axis of an omnidirectional image sensor is first extracted by generating autocorrelation images from omnidirectional images containing global information that is useful for self‐localization. Next, eigenspaces are formed from the generated autocorrelation images, and self‐localization is performed by searching for the learning images that are closest to the input image in the eigenspace. Additionally, performing self‐localization in two stages (general and local) results in robust self‐localization. Lastly, experiments were conducted using time‐series omnidirectional images that were actually captured both indoors and outdoors to verify the effectiveness of the proposed method. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 56–68, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1203
Multiple beamforming with source localization based on CSP analysis
Authors: Nishiura Takanobu , Nishioka Ryousuke , Yamada Takeshi , Nakamura Satoshi , Shikano Kiyohiro 
Published: March 2003

AbstractIn this paper, a method is investigated for using an array of microphones to capture a high‐quality recording of voice under reverberation. In the past, multiple beamforming has been proposed by Flanagan's group as a method for efficiently suppressing reverberation. However, because this multiple beamforming method computes the arrival positions of the sound and its reflections based on the prior knowledge of the shape of the room and the position of the target sound source, it is not suited to practical applications. In this paper, a method of multiple beamforming is proposed in which the source positions of the sound and its reflections are localized without using prior knowledge of the shape of the room or the position of the target sound source. The effectiveness of the proposed method was evaluated in a simulation experiment using the image method and in an experiment in an actual hallway environment. First, an experiment was run to localize the positions of the sources of the sound and its reflections under a condition in which both the shape of the room and the source position of the sound were unknown. As the result, it was found that the localization error for the source position of the sound was small. Furthermore, although the localization errors for the source positions of the reflections were large, the localized reflection paths were found to be approximately equal to the true reflection paths. Next, the output signal from the proposed method was evaluated based on SNR. The result demonstrated that multiple beamforming is more effective than single beamforming. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 69–80, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1204
Ranking of documents by measures considering conceptual dependence between terms
Authors: Nakashima Makoto , Kaneko Yuichi , Ito Tetsuro 
Published: March 2003

AbstractThere is demand for a retrieval system that would support extraction of documents even without recognizing new query expressions, while offering a user interface featuring an easy way to evaluate relevance of search results. In this paper, a solution to such a need is offered. Topics of queries and documents are normally represented by search terms. Thus, terms are assumed to be associated through a concept hierarchy; measures are found that reflect, in a natural way, conceptual relations between terms through associativity between a query and a document; a method is developed to rank documents using such measures. These measures consider specificity of coverings of expressions mentioned in both the query and the document with regard for concept hierarchy. Experiments confirmed that the proposed measures were helpful in evaluating conceptual associativity, while document ranking based on these measures proved more efficient compared to traditional similarity measures. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 81–91, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1205
Proactive environmental strategies: a stakeholder management perspective
Authors: Buysse Kristel , Verbeke Alain 
Published: March 2003

AbstractThis paper includes an empirical analysis of the linkages between environmental strategy and stakeholder management. First, it is shown that several simultaneous improvements in various resource domains are required for firms to shift to an empirically significant, higher level of proactiveness. Second, more proactive environmental strategies are associated with a deeper and broader coverage of stakeholders. Third, environmental leadership is not associated with a rising importance of environmental regulations, thereby suggesting a role for voluntary cooperation between firms and government. Finally, the linkages between environmental strategies and stakeholder management, based on a sample of 197 firms operating in Belgium, appear more limited than expected. Country‐specific characteristics may to a large extent account for these results. Copyright © 2002 John Wiley & Sons, Ltd.
Environmental dynamism and strategic decision‐making rationality: an examination at the decision level
Authors: Hough Jill R. , White Margaret A. 
Published: March 2003

AbstractSeveral approaches have been used to explore environmental dynamism as a contingent predictor of the relationship between rational‐comprehensive strategic decision‐making and firm‐level performance. At the decision level of analysis, however, small sample sizes, low statistical power, and statistical dependence have plagued the research. Through the use of a simulated decision‐making environment and multilevel analysis, this study examined 400 decisions from 54 executive teams. Consistent with much of the existing firm‐level research, the results indicated that environmental dynamism may moderate the relationship between rational‐comprehensive decision making and decision quality. Surprisingly, the form of the relationship differed from much of the firm‐level research. Copyright © 2003 John Wiley & Sons, Ltd.
QoS customization in distributed object systems
Authors: He Jun , Hiltunen Matti A. , Rajagopalan Mohan , Schlichting Richard D. 
Published: March 2003

AbstractApplications built on networked collections of computers are increasingly using distributed object platforms such as CORBA,Java Remote Method Invocation (RMI), and DCOM to standardize object interactions. With this increased use comes the increased need for enhanced quality of service (QoS) attributes related to fault tolerance, security, and timeliness. This paper describes an architecture called CQoS (configurable QoS) for implementing such enhancements in a transparent, highly customizable, and portable manner. CQoS consists of two parts: application‐ and platform‐dependent interceptors and generic QoS components. The generic QoS components are implemented using Cactus, a system for building highly configurable protocols and services in distributed systems. The CQoS architecture and the interfaces between the different components are described, together with implementations of QoS attributes using Cactus and interceptors for CORBA and Java RMI. Experimental results are given for a test application executing on a Linux cluster using Cactus/J, the Java implementation of Cactus. Compared with other approaches, CQoS emphasizes portability across different distributed object platforms, while the use of Cactus allows custom combinations of fault‐tolerance, security, and timeliness attributes to be realized on a per‐object basis in a straightforward way. Copyright © 2003 John Wiley & Sons, Ltd.
From pattern to process: identifying predator–prey models from time‐series data
Authors: Jost C. , Arditi R. 
Published: March 2003

AbstractFitting nonlinear models to time‐series is a technique of increasing importance in population ecology. In this article, we apply it to assess the importance of predator dependence in the predation process by comparing two alternative models of equal complexity (one with and one without predator dependence) to predator–prey time‐series. Stochasticities in such data come from both observation error and process error. We consider how these errors must be taken into account in the fitting process, and we develop eight different model selection criteria. Applying these criteria to laboratory data on simple protozoan and arthropod predator–prey systems shows that little predator dependence is present, with one interesting exception. Field data are more ambiguous (either selection depends on the particular criterion or no significant differences can be detected), and we show that both models fit reasonably well. We conclude that, within our modeling framework, predator dependence is in general insignificant in simple systems in homogeneous environments. Relatively complex systems show significant predator dependence more often than simple ones but the data are also often inconclusive. The analysis of such systems should rely on several models to detect predictions that are sensitive to predator dependence and to direct further research if necessary.
On‐Line Optimization of Recombinant Product in a Fed‐Batch Bioreactor
Authors: Mahadevan Radhakrishnan , III Francis J. Doyle 
Published: April 2003

AbstractIn this paper, an efficient scheme for on‐line optimization of a recombinant product in a fed‐batch bioreactor is presented. This scheme is based on the parametrization of the system states and the elimination of a subset of the dynamic equations in the mathematical model of the fed‐batch bioreactor. The fed‐batch bioreactor considered here involves the production of chloramphenicol acetyltransferase (CAT) in a genetically modified E. coli. The optimal inducer and the glucose feed rates are obtained using the proposed optimization approach. This approach is compared with the traditional optimization approach, where all the states and the manipulated variables are parametrized. The approach presented in this paper results in a 5‐fold improvement in the computational time for the recombinant product optimization. The optimization technique is employed in an on‐line optimization scheme, when parametric drift and a disturbance in the manipulated variable is present. Feedback from the process is introduced through resetting the initial conditions of the model and through an observer for estimating the time varying parameter. The simulation results indicated improvement in the amount of product formed, when the optimal profile is regenerated during the course of the batch.
Evolution of Culture Broth Rheological Properties during Propagation of the Entomopathogenic Nematode Steinernemacarpocapsae, in Submerged Monoxenic Culture
Authors: Chavarría‐Hernández Norberto , Inés Rodríguez‐Hernández Adriana , Pérez‐Guevara Fermín , Torre Mayra de la 
Published: April 2003

AbstractThis article presents the evolution of culture broth rheological properties during monoxenic cultures of Steinernema carpocapsaein cylindrical bottles agitated orbitally. Rheological properties were evaluated in simple‐shear flow conditions and were well‐modeled by the Ostwald‐de Waele model. Rheological properties varied from slightly dilatant, n= 1.2 (–), to moderately pseudoplastic flow behavior, n= 0.6 (–). Nematode concentrations increased from 750 ± 190 to 130 900 ± 6900 nematodes/mL, and the apparent viscosity (ηa) evolved from 4.5 ± 0.7 to 46.6 ± 3.2 mPa·s during the fermentations. Rheological behavior did not appear to be strongly influenced by nematode number and/or its stage of development; however, the release of substances from the decomposition of nematode cadavers appeared to be of great importance. Among the different developmental stages of the nematodes, only juveniles of the first stage (J1) were highly susceptible to the shearing conditions tested (shear stress, θrθ, from 0.9 to 3.5 Pa during periods of 80–100 min), resulting in the viability loss of 85% of J1 nematodes.