bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inverse filtering and deconvolution
Authors: Saberi Ali , Stoorvogel Anton A. , Sannuti Peddapullaiah 
Published: September 2002

AbstractThis paper studies the so‐called inverse filtering and deconvolution problem from different angles. To start with, both exact and almost deconvolution problems are formulated, and the necessary and sufficient conditions for their solvability are investigated. Exact and almost deconvolution problems seek filters that can estimate the unknown inputs of the given plant or system either exactly or almostly whatever may be the unintended or disturbance inputs such as measurement noise, external disturbances, and model uncertainties that act on the system. As such they require strong solvability conditions. To alleviate this, several optimal and suboptimal deconvolution problems are formulated and studied. These problems seek filters that can estimate the unknown inputs of the given system either exactly, almostly or optimally in the absence of unintended (disturbance) inputs, and on the other hand, in the presence of unintended (disturbance) inputs, they seek that the influence of such disturbances on the estimation error be as small as possible in a certain norm (H2orH∞) sense. Both continuous‐ and discrete‐time systems are considered. For discrete‐time systems, the counter parts of all the above problems when an 𝓁‐step delay in estimation is present are introduced and studied. Next, we focus on the exact and almost deconvolution but this time when the uncertainties in plant dynamics can be structurally modeled by a Δ‐block as a feedback element to the nominally known plant dynamics. This is done either in the presence or absence of external disturbances. Copyright © 2001 John Wiley & Sons, Ltd.
Uses of solar radiation pressure for satellite formation flight
Authors: Williams Trevor , Wang Zhong‐Sheng 
Published: September 2002

AbstractOne fundamental way in which satellite formation flight differs from conventional orbital proximity operations is that extended mission durations are required. Consequently, long‐term perturbation effects, and in particular, those due to the oblateness of the Earth, must be corrected for if the formation is to persist. This paper considers a novel non‐propulsive means for countering the differential orbital plane precession that is the major formation perturbation produced by oblateness. The approach taken is to make use of the solar radiation pressure acting on a relatively small surface, termed a solar wing, that is fixed to the satellite. The resulting torque causes the orbit to precess; if the wing is sized correctly, this motion will cancel, on average, with that due to oblateness, so maintaining the formation without use of propellant. It will be shown that the long‐term orbital effects of the solar wing control input (the wing orientation angle) are highly nonlinear, and exhibit strong coupling between the orbital inclination and the longitude of the ascending node. Finally, numerical results are given to illustrate the approach. Copyright © 2002 John Wiley & Sons, Ltd.
Co‐ordination and control of distributed spacecraft systems using convex optimization techniques
Authors: Tillerson Michael , Inalhan Gokhan , How Jonathan P. 
Published: September 2002

AbstractFormation flying of multiple spacecraft is an enabling technology for many future space science missions. However, the co‐ordination and control of these instruments poses many difficult design challenges. This paper presents fuel/time‐optimal control algorithms for a co‐ordination and control architecture that was designed for a fleet of spacecraft. This architecture includes low‐level formation‐keeping algorithms and a high‐level fleet planner that creates trajectories to re‐size or re‐target the formation. The trajectory and formation‐keeping optimization algorithms are based on the solutions of linear and integer programming problems. The result is a very flexible optimization framework that can be used off‐line to analyse various aspects of the mission design and in real time as part of an onboard autonomous formation flying control system. The overall control approach is demonstrated using a nonlinear simulation environment that includes realistic measurement noises, disturbances, and actuator nonlinearities. Copyright © 2002 John Wiley & Sons, Ltd.
On the design of gain‐scheduled trajectory tracking controllers
Authors: Silvestre Carlos , Pascoal Antonio , Kaminer Isaac 
Published: September 2002

AbstractA new methodology is proposed for the design of trajectory tracking controllers for autonomous vehicles. The design technique builds on gain scheduling control theory. An application is made to the design of a trajectory tracking controller for a prototype autonomous underwater vehicle (AUV). The effectiveness and advantages of the new control laws derived are illustrated in simulation using a full set of non‐linear equations of motion of the vehicle. Copyright © 2002 John Wiley & Sons, Ltd.
Sampled‐data implementation of a gain scheduled controller
Authors: Stilwell Daniel J. , Lawrence Douglas A. 
Published: September 2002

AbstractA continuous‐time gain‐scheduled controller must be transformed to a corresponding discrete‐time controller for sampled‐data implementation. We show that certain linearization properties of a continuous‐time gain scheduled controller are inherited by its sampled‐data implementation. We also show that a similar relationship exists for multi‐rate gain scheduled controllers arising in flight control applications. Copyright © 2002 John Wiley & Sons, Ltd.
Control of a six‐axis pneumatic robot
Authors: Mattiazzo G. , Mauro S. , Raparelli T. , Velardocchia M. 
Published: September 2002

AbstractThe article presents a control system for a six‐degree of freedom (DOF) anthropomorphic robot powered entirely by pneumatic actuators. The control uses digital valves driven by pulse width modulation (PWM) to regulate air flow to the actuators. The robot is equipped with position sensors, which are used to provide feedback signals for local fuzzy controllers actuating the individual servoaxes. Trajectory tracking is guided by a module, which computes the robot's inverse kinematics, generating the references for the servoaxes. Experimental results illustrated in the article indicate that the controller is effective both in controlling single axes, and in tracking a trajectory. © 2002 Wiley Periodicals, Inc.
Joint tracking controller for multi‐link flexible robot using disturbance observer and parameter adaptation scheme
Authors: Cheong Joono , Youm Youngil , Chung Wan Kyun 
Published: September 2002

AbstractAn improved composite controller of singular perturbation approach is designed for controlling a multi‐link flexible robot with uncertainties. We adopt the standard form of a singular perturbation approach for modeling. To reduce the coupling effect from flexibility, the bandwidth of a slow subsystem is modulated by considering the fundamental frequency. The disturbance observer provides a means for defining the bandwidth of a slow subsystem as well as compensating disturbances. At the same time, uncertainties in the fast subsystem are updated to enhance the capability for vibration suppression in conjunction with PID (Proportional‐integrative derivative) modal feedback. We draw conditions for Lyapunov stability of the modal feedback and adaptive scheme. A numerical simulation will support the validity of our research results. © 2002 Wiley Periodicals, Inc.
On the expected value of the minimum assignment
Authors: Buck Marshall W. , Chan Clara S. , Robbins David P. 
Published: September 2002

AbstractThe minimum k‐assignment of an m × n matrix X is the minimum sum of k entries of X, no two of which belong to the same row or column. Coppersmith and Sorkin conjectured that if X is generated by choosing each entry independently from the exponential distribution with mean 1, then the expected value of its minimum k‐assignment is given by an explicit formula, which has been proven only in a few cases. In this paper we describe our efforts to prove the Coppersmith–Sorkin conjecture by considering the more general situation where the entries xij of X are chosen independently from different distributions. In particular, we require that xij be chosen from the exponential distribution with mean 1/ricj. We conjecture an explicit formula for the expected value of the minimum k‐assignment of such X and give evidence for this formula. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 33–58, 2002
Image data compression with nonuniform block segmentation and luminance approximation using bilinear curved surface patches
Authors: Hasegawa Makoto , Yamasaki Issei 
Published: September 2002

AbstractA grayscale image is subdivided into nonuniform blocks and luminance values in each block are approximated by a bilinear curved surface patch. (1) Comparison with a method using triangular plain patches shows that a bilinear curved surface patch is more efficient. (2) Encoding luminance values on block vertices which construct patch is discussed. A method of encoding by adaptive prediction with Z‐scanning is proposed. (3) The S/N of the reconstructed image (ITE test chart: a portrait with monotonous background under 0.38 bpp) is higher than the case of down‐sampling JPEG. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(10): 31–40, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10097
A dynamical model of figure‐ground reversal perception based on the role of visual attention
Authors: Yasukochi Ken , Sakaguchi Yutaka 
Published: September 2002

AbstractIn an attempt to clarify the dynamical process in human visual perception, we propose a neural network model explaining the figure‐ground reversal phenomenon of a three‐dimensional ambiguous figure, and examine its behavior in numerical experiments. In contrast to conventional models that explain perceptual reversal at a “symbolic representation level” using the oscillation between two memorized patterns in a network, our model tries to explain this phenomenon at a “structural representation level.” That is, the model has a field that represents the 3D structure of the visual input and the spatial distribution of visual attention, where the attention and structural representation interact with each other to bring dynamical change in the perceived structure. Another important feature of our model is that it reflects both space‐oriented and object‐oriented properties of visual attention. By discussing the structure and operation of our model, we introduce the concept of the “dynamics of perception and attention” as a general framework for understanding the dynamical transition of human visual perception. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(10): 21–30, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10104
Extraction and classification of pulmonary organs based on thoracic 3D CT images
Authors: Tozaki Tetsuya , Kawata Yoshiki , Niki Noboru , Ohmatsu Hironobu 
Published: September 2002

AbstractRecent progress in helical CT technology has given rise to considerable interest and expectations regarding diagnosis based on 3D CT images. In this context, computer‐aided diagnosis techniques for 3D CT images are required. This study introduces a method for analysis of thoracic 3D CT images, which contain important information for lung cancer diagnosis. The lung field includes the bronchi and pulmonary arteries and veins, as well as other organs; lung cancer influences these organs in a complicated and intermixed way. The proposed method supports extraction and classification of bronchi, arteries, and veins from thoracic 3D CT images using anatomical knowledge and 3D image processing technologies, and analysis of the relations between these pulmonary organs and suspected lung cancer. The extraction of pulmonary organs includes removal of bias components, extraction of bronchi and blood vessels, discrimination between bronchi and blood vessels, and identification of arteries and veins among blood vessels. Quantitative relations between suspected lung cancer and adjacent pulmonary organs are found. The effectiveness of the proposed method is shown using 3D CT images of healthy and cancerous lungs. © 2001 Scripta Technica, Syst Comp Jpn, 32(9): 42–53, 2001
A stochastic speech understanding method to generate interlingual representations
Authors: Tanigaki Koichi , Sagisaka Yoshinori 
Published: September 2002

AbstractThe purpose of this paper is to create an understanding system that can reduce the recognition error that prevents semantic analysis, and that is robust to speech input. A method is proposed in which semantic analysis and speech recognition are integrated on the basis of a statistical model, and the procedure is optimized as a high‐level recognition process from speech to semantics. As a method of realizing the idea effectively and efficiently, search of the word graph by means of a decision tree is proposed. Using the proposed method, an identification experiment is performed for the semantics represented by the intermediate language. It is a problem of segmentation of utterances into an average of 1.6 semantic units, and the assignment of the semantic units to 7600 classes characterized by combinations of utterance action and concept. In the speech recognition experiment the understanding error is improved by 8.5% compared to the case in which the 1‐best recognition candidate is input. © 2002 Scripta Technica, Syst Comp Jpn, 33(3): 52–62, 2002
Shell, Nigeria and the Ogoni. A study in unsustainable development: II. Corporate social responsibility and ‘stakeholder management’ versus a rights‐based approach to sustainable development
Authors: Boele Richard , Fabig Heike , Wheeler David 
Published: September 2002

AbstractIn the first paper in this trilogy (Boeleet al., 2001) we described the history of the Royal Dutch/Shell Group from its inception in 1890 through to the year 2000, discussed briefly the importance of corporate reputation to the group and described the significant impacts on Shell of the events of 1995 in Nigeria. We traced the relationship of the Shell Petroleum Development Corporation in Nigeria to impacts on the natural and social environments of the Niger Delta and more specifically on the Ogoni. Finally we discussed the emergence of political resistance and significant conflict between Shell and the Movement for the Survival of the Ogoni People (MOSOP) and concluded that, despite significant apparent changes in attitude at the group level, distrust and antipathy towards Shell remained entrenched in Ogoni. In this second paper, we explore in more detail issues raised by economic globalization for the practice of corporate social responsibility and stakeholder management, and contrast these concepts with an alternative ‘rights‐based’ approach to sustainable development. We relate our observations to Shell's current approach and conclude that the Shell group and specifically the Shell Petroleum Development Corporation in Nigeria may require an alternative approach to sustainable development if they wish to merit the full confidence of communities in areas of the world as complex and distressed as Ogoni. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment
Towards strategic planning and regional sustainability: Hong Kong in the Pearl River Delta Region
Authors: Chan Roger C. K. 
Published: September 2002

AbstractThis paper examines the wider spatial and governmental context for promoting sustainable development policies in Hong Kong. It examines the spatial frameworks and the territory‐specific approaches adopted in Hong Kong since the 1970s. Despite the claim of a non‐interventionist approach, government intervention for the purposes of promoting economic growth was evident in the development model of Hong Kong under the British rule. Additionally, the notion of strategic planning at the regional level was absent from the spatial framework. This was so even with the growing economic interaction between Hong Kong and the other cities in the Pearl River Delta Region (PRDR) in the 1980s and remained so in the early years of the SAR government. With economic integration between Hong Kong and the PRDR, strategic planning has to take on a different form. The diversity of the socio‐economic context and the complexity of political processes in the PRDR offer enormous opportunities to all stakeholders. Hong Kong should be more proactive in bringing the region together with a view to attaining regional sustainability. Copyright © 2002 John Wiley & Sons, Ltd. and ERP Environment.
Environmental policy and planning in Hong Kong: an emerging regional agenda
Authors: Hills Peter 
Published: September 2002

AbstractFor the past 20 years, environmental policy in Hong Kong has been driven by responses to a variety of local problems resulting in an array of environmental ordinances and supporting regulations addressing air, water and noise pollution problems, waste management and the use of EIA in the development planning process. Hong Kong's approach to environmental policy has been based on the conventional ‘command and control’ model of environmental management. It has, however, become increasingly apparent that many of Hong Kong's environmental problems cannot be effectively addressed solely by local initiatives but must involve broader collaborative efforts with authorities in neighbouring Guangdong Province. Furthermore, the Hong Kong SAR's efforts to address sustainability issues, which are still at an early stage, may also be facilitated by a regional rather than purely local perspective as well as by one that explores the utility of the ecological modernization model. This paper discusses the recent evolution of environmental policy in Hong Kong, the emergence of a regional environmental management agenda and the potential of ecological modernization as a basis for the development of a broader strategy to manage the environmental problems of the Pearl River Delta Region. Copyright © 2002 John Wiley & Sons, Ltd. and ERP Environment.
The Scottish strategic and spatial context for sustainable development
Authors: Roberts Peter 
Published: September 2002

AbstractThis paper examines the strategic spatial context for sustainable development in Scotland. In providing this contextual overview the paper considers the influence of European Union policies and the evolution of Scottish and UK thinking. Particular emphasis is placed on the recent introduction of the idea of preparing a Scottish national spatial planning framework. Copyright © 2002 John Wiley & Sons, Ltd. and ERP Environment.
Sustainable development and the management of the Scottish environment: stringing the beads
Authors: Roberts Peter , Jackson Tony 
Published: September 2002

AbstractThis paper examines the environmental dimension of sustainable development policy and practice in Scotland. Among the issues considered in the paper are matters related to the political context for environmental policy and the evolution of statutory responsibilities. Looking forward, the paper assesses the growing influence of the European Union on environmental issues and calls for the establishment of a more integrated approach to policy. Copyright © 2002 John Wiley & Sons, Ltd. and ERP Environment.
The Global 2000 Report to the President and the Threshold 21 model: influences of Dana Meadows and system dynamics
Authors: Barney Gerald O. 
Published: September 2002

AbstractThe author first met Dana Meadows and her colleagues in the Limits to Growth project during a postdoctoral year at MIT, setting the author on a new career and life path. The first major step was directing the Global 2000 Report for President Jimmy Carter. In the Global 2000 project, we improved the connections and consistency among the sector‐specific elements of the Government's Global Model. The results of the projections were generally consistent with the Limits study, but analysis showed that the Government's models were biased optimistically because of omitted feedbacks. Another major step was the establishment of Millennium Institute (MI) and the development of the Threshold 21 (T21) integrated national development model. There are no global decision makers who can address the global issues of Limits; humanity's global decisions are largely the combined consequences of national level decisions. MI's T21 model provides an analytical tool for ministers of finance and planning that produces the same financial and monetary outputs as the models used by the World Bank and IMF, but that also address the social and environmental aspects of national sustainability issues. After more than a decade of work, T21 has gained much respect and has been customized to more than a dozen countries, industrialized as well as developing. In addition to describing the influence of Dana and system dynamics on the author's life, the article sketches out work needed for the future. Copyright © 2002 John Wiley & Sons, Ltd.
The electronic oracle: computer models and social decisions
Authors: Meadows Donella H. , Robinson Jennifer M. 
Published: September 2002

AbstractThis paper is an excerpt from The Electronic Oracle: Computer Models and Social Decisions (Chichester: John Wiley & Sons, 1985), by the late Donella Meadows and Jennifer Robinson. The book investigates the practice and impact of systems analysis and computer modeling, particularly as applied to social policy. The authors explore the nature of models, the biases and hidden assumptions of different modeling methods, the pragmatics of the modeling process, and the impact of modeling on the real world. These issues are approached through detailed case studies of nine models designed to address issues of economic development, resources and the environment. The models used methods including econometrics, linear programming, input/output analysis, and system dynamics. Though the models were “identified as ‘better than average’” by the authors and by “other modelers, clients, and sponsors,” Meadows and Robinson (p. 104) found “mismatches of methods with purposes, sloppy documentation, absurd assumptions buried in overcomplex structures, conclusions that do not even follow from model output, and project management strategies that destroy the possibility of influencing actual policy.” The record in the world of business modeling is at least as dismal. The excerpt presented here focuses on implementation. The authors explore why so many modeling projects fail and present guidelines for improvement. The methods developed in the book to expose hidden assumptions, to make undiscussable values and biases discussable, remain central to anyone seeking to have an impact on the real world. The book both anticipated and shaped important developments, including the focus on ‘modeling for learning,’ group model building, and the systems thinking and organizational learning movements. Yet despite welcome advances in hardware, software, and modeling methods since the book was written, we have not yet realized the authors' vision of a world in which modelers are not only scientific and rigorous, but also “compassionate, humble, open‐minded, responsible, self‐insightful, and committed.” John Sterman Copyright © 1985 International Institute for Applied Systems Analysis. Reprinted by permission.