bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability, robustness and approximation properties of gradient recurrent high‐order neural networks
Authors: Kosmatopoulos E. B. , Christodoulou M. A. 
Published: July 2007

AbstractGradient recurrent high‐order neural networks (GRHONNs) have found great applicability to optimization, associative memory, adaptive signal‐processing and system identification problems. In this paper we show that these neural networks are asymptotically stable dynamical systems and, moreover, that their solutions remain stable under either deterministic or stochastic disturbances. We also prove that GRHONNs are dense in the space of continuous dynamical systems, contrary to the fact that their vector fields do not satisfy the Stone‐Weierstrass theorem. the significance of these theoretical results to associative memory and optimization and to the fabrication of general‐purpose, large‐scale hardware implementations is discussed.
Robust adaptive quantization: A Kalman‐filter‐based approach
Authors: Crisafulli Sam , Bitmead Robert R. 
Published: July 2007

AbstractAdaptive quantizers/dequantizers are systems that are used to quantize efficiently signals with a large variation in short‐term variance. They are typically found in telecommunication systems where highly non‐stationary signals such as speech need to be represented digitally with the minimum number of bits. Channel errors that are introduced owing to non‐ideal transmission significantly reduce the performance of adaptive dequantizers. In this paper we extend recent Kalman‐filter‐based adaptive quantization techniques to arrive at new dequantization schemes which are more robust to channel errors. This is achieved by utilizing the estimates produced by a Kalman filter based on a linear signal model which embodies the entire encoder/channel combination. Extensions to Kalman smoothing based on the same signal model result in further performance improvement at the expense of a small delay.
A vectorized systolic array for parallel weight extraction of block RLS
Authors: Sakai Hideaki 
Published: July 2007

AbstractA new vectorized systolic array for extracting weight coefficients in block RLS is proposed. Our array is based on a generalization of the inverse factorization method of Pan and Plemmons and the array for computing residual vectors in block RLS using the Householder transformation of Liu et al. the new array is obtained by first generalizing the inverse factorizations for the block case and then deriving a formula for updating the tap coefficients without matrix operations.
Blind equalizers with simulated annealing optimization for digital communication systems
Authors: Ilow J. , Hatzinakos D. , Venetsanopoulos A. N. 
Published: July 2007

AbstractNew batch‐type methods and their recursive extensions are introduced for blind equalization of digital communication channels. Based on the underlying cost function of the existing Bussgang and cumulantfitting algorithms, simulated annealing (SA) optimization is successfully employed to identify and equalize the communication channels.Many of the existing blind equalization algorithms utilize a stochastic gradient approach to minimize non‐linear cost functions. Owing to the multimodal nature of these functions, the gradient algorithms might converge to the wrong solution. In contrast, the proposed methods are based on a global optimization algorithm. the SA algorithm tends to avoid the local minima encountered.The feasibility and convergence behaviour of the proposed algorithms are examined by means of computer simulations. Computational complexity issues in the implementation of the algorithms are discussed.
Reduced Kalman filtering for indirect adaptive control of the induction motor
Authors: Glielmo L. , Marino P. , Setola R. , Vasca F. 
Published: July 2007

AbstractParameter variations strongly affect the application of indirect field‐oriented control (FOC) of the induction motor. To estimate those parameters which cannot be obtained by means of a direct measure, an augmented state observer can be constructed; in particular, the presence of noise introduced by the inverter and sensors suggests the use of an extended Kalman filter (EKF). In this paper, by analysing the indirect FOC technique via a two‐time‐scale approach, we formally justify its effectiveness and propose a reduced‐order EKF which is used to construct an adaptive version of the FOC method. The practical drawback of reduced‐order EKFs, i.e. the necessity to differentiate measured quantities, is avoided by exploiting some peculiarities of the field‐oriented controller.
Adaptive tuning of fuzzy logic identifier for unknown non‐linear systems
Authors: Liu Kai , Lewis Frank L. 
Published: July 2007

AbstractAn on‐line approximator using a linear fuzzy logic model with automatic tuning mechanism is presented in this paper. the proposed approximation method can be used to model a class of unknown non‐linear systems as long as they are Caratheodory ones. the structure of the fuzzy model is fixed but the parameters are tuned by the state errors. the fuzzy model is composed of several semi‐closed, continuous, totally ordered and well‐defined fuzzy numbers defined in each state variable dimension and a number of appropriately defined condition‐action rules. Either the min‐inference or product‐inference technique is utilized to generate the weighted average of the linear coefficients which make the whole unknown non‐linear system piecewise linearized. No off‐line preprocessing is needed. the initial values of the parameters of the fuzzy model can be arbitrarily assigned. Then they are tuned to their true values through adaptive update law and therefore it is guaranteed that the unknown non‐linear system is linearized and approximated to any degree of accuracy by the linear fuzzy logic model.
Deconvolution with bounded uncertainty
Authors: Combettes Patrick L. , Trussell H. Joel 
Published: July 2007

AbstractIn deconvolution problems there are two primary sources of uncertainty in the data formation mechanism, namely measurement noise and errors in the model of the system. In this paper we develop an abstract set theoretic deconvolution framework for problems in which the only information available about these sources of uncertainty consists of bounds. Iterative methods based on projections are used to generate solutions consistent with these bounds, the output data signal and a priori knowledge about the input signal. an example of application of this general framework to discrete signal recovery is demonstrated.
Adaptive control in a heating vessel: A comparative study
Authors: Pérez‐Correa J. R. , Sepúlveda F. R. , Duarte M. A. 
Published: July 2007

AbstractThis paper presents experimental results obtained in temperature adaptive control of a heating vessel. A non‐linear model of the process showed that the feed flow rate causes severe variations in time constant and process gain. An extended horizon self‐tuning controller and two different model reference adaptive controllers were tested. The influence of design parameters on control performance for each algorithm was assessed. The control system was disturbed with load and setpoint changes.
Design of adaptive feedforward algorithms using internal model equivalence
Authors: Messner William , Bodson Marc 
Published: July 2007

AbstractThe paper investigates the design of adaptive feedforward cancellation (AFC) algorithms with sinusoidal regressors for repetitive control. Such adaptive algorithms are equivalent to linear controllers based on the internal model principle (IMP). Using this equivalence and root locus rules, the phase advance of the regressor of the adaptive algorithm can be chosen to maximize the phase margin at low gains. A surprising result is that selecting the optimal phase advance is equivalent to placing a zero in the open right half‐plane in certain cases. A complete design and analysis for the compensation of a single‐frequency periodic disturbance is done. A new variation of the AFC algorithm is also developed in which the adaptive portion acts in parallel with a feedthrough term. the IMP equivalent of this algorithm has two zeros instead of one. Analysis and simulation show this method to have superior convergence and robustness properties when compared with the method having no feedthrough term. Discrete time versions of the algorithms are briefly considered.
Self‐oscillating adaptive design of systems with dry friction and significant parameter uncertainty
Authors: Oldak S. , Gutman P. O. 
Published: July 2007

AbstractMotion control systems with dry friction and high‐order uncertain plants suffer from one or more limit cycles which can be predicted with describing function theory. In this paper quantitative design theory is presented to satisfy given frequency domain tolerances in these systems. The case of linear time‐invariant (LTI) compensation is studied first. Then it is shown how, in those systems with a limit cycle, self‐oscillating design with an adaptive loop (SOAL) can be used to reduce the LTI compensator bandwidth for a large class of problems.
Approximate gradients, convergence and positive realness in recursive identification of a class of non‐linear systems
Authors: Wigren Torbjörn 
Published: July 2007

AbstractRecursive identification algorithms based on the Wiener model are presented in this paper. They estimate the parameters of a SISO linear dynamic block in cascade with a known static output non‐linearity. Inversion of the non‐linear function is avoided and approximations of gradients are utilized. This allows an exact treatment of output measurement saturation and of situations where output measurements are obtained from sensors with relay‐type characteristics, such as EGO sensors in emission control systems for cars. Exact compensation for coarse quantization of output measurements can also be obtained by the algorithms. Stochastic averaging techniques using associated differential equations prove that local and global convergence of the schemes are tied to positive realness and sector conditions on the non‐linearity. Conditions for local convergence to the correct parameters are established for the case where the output non‐linearity is an arbitrary quantizer.
Smoothing with adaptive rank order filters for early processing in image segmentation
Authors: Zamperoni Piero 
Published: July 2007

AbstractThis paper describes two non‐linear smoothing filters based on adaptive rank order filtering. the ideal output of these filters is a grey value suitable for characterizing the grey value distribution associated with the local texture, i.e. suitable for use as a region label for image segmentation purposes. the problem is to select as output a grey value that is stable with respect to the fluctuations of the local grey value distribution inside homogeneous regions. the first proposed method aims at the estimation of the mode of the local distribution. the second selects the output rank in dependence on the local average; it is simpler and combines the edge‐sharpening advantages of ‘comparison and selection filters’ with a better mode estimation, in comparison with the median filter, in the presence of asymmetrical local grey value distributions.
Real‐time implementation of an indirect adaptive robot controller
Authors: Dessaint L.‐A. , Saad Maarouf , Hebert Bernard , Robert Sylvain 
Published: July 2007

AbstractAdaptive controllers applied to high‐speed and high‐precision robot manipulators give excellent tracking performances because they take into account the full dynamics of the robot. Recent publications have shown that on‐line estimation of the dynamic constant parameters can be obtained by the joint tracking error (direct adaptive control) or by the torque prediction error (indirect adaptive control).In direct adaptive controllers the estimation law is derived from Lyapunov stability or Popov hyperstability methods. These controllers are simple and their real‐time implementation is easy; however, the estimation is not so accurate. In indirect adaptive controllers the estimation law is based on a least squares algorithm. These controllers give accurate estimates of the manipulator parameters; however, they involve much more computation than the direct approach. Therefore no real‐time implementations of indirect adaptive tracking controllers for robots have been reported in the literature until now.This paper describes a real‐time implementation of an indirect adaptive scheme applied to a two‐degree‐of‐freedom (2DOF) direct‐drive SCAM robot. the controller is implemented at low cost by the use of a single‐chip digital signal processor (DSP).
A robust decentralized three‐segment nonlinear sliding mode control for rigid robotic manipulators
Authors: Zhihong Man , Palaniswami M. 
Published: July 2007

AbstractIn this paper the design of three‐segment non‐linear sliding mode parameters is further investigated and a robust decentralized tracking control scheme using the three‐segment non‐linear sliding mode technique for non‐linear rigid robotic manipulators is developed. It is shown that some parameters of the three‐segment non‐linear sliding mode are related to the initial values of the system dynamics and should be suitably chosen in order to guarantee the stability of the system dynamics. Strong robustness and fast error convergence can be obtained for rigid robotic manipulators with large uncertain dynamics by using the three‐segment non‐linear sliding mode technique together with a few useful smctural properties of rigid robotic manipulators. A simulation example is given in support of the proposed control scheme.
Distinguishing Concepts: Lexicons of Interactive Art and Architecture
Authors: Haque Usman 
Published: July 2007

AbstractInteractive design has come about as a result of the intermingling of disciplines. As a consequence, the language it uses has become blurred ‐ borrowed or stolen with little restraint from elsewhere. Though particular terms have become ubiquitous, the original concepts that lie behind them have been lost. This means that all too frequently they are no longer knowingly used. Usman Haque sorts the wheat from the chaff and brings clarity to bear on the vocabulary and thinking behind interactivity. Copyright © 2007 John Wiley & Sons, Ltd.
Food pricing, competition, and the emerging supercenter format
Authors: Stiegert Kyle W. , Sharkey Todd 
Published: July 2007

AbstractMuch previous research has examined the role of concentration, level of service, and entry barriers on U.S. food retailing profits and prices. Despite the rapid advancement of food supercenters, public policy research evaluating their price impacts remains quite limited. The purpose this study is to examine the price impacts from supercenter entry, growing supercenter market share, and supermarket consolidation from 1993–2003. Findings were that both the market share of supercenter food sales and the marginal impact of supercenter entry did not have a significant impact on food prices in the metropolitan statistical areas (MSAs) analyzed. These are important findings in light of claims that supercenters entry causes a procompetitive effect. Futhermore, changes in market concentration was significantly and positively related to price changes. Therefore, it appears consolidation led to higher prices and any merger‐related cost gains during this period were not passed on to consumers. [EconLit Classifications: D400, L130, L660]. © 2007 Wiley Periodicals, Inc. Agribusiness 23: 295–312, 2007.
Beef safety shocks and dynamics of vertical price adjustment: The case of BSE discovery in the U.S. beef sector
Authors: Saghaian Sayed H. 
Published: July 2007

AbstractThis article addresses the dynamic impact of the 2003 Bovine Spongiform Encephalopathy discovery on the U.S. beef sector. Time series analysis and historical decomposition with weekly feedlot, wholesale, and retail beef price series is used to address the dynamics of price adjustment and causality along the U.S. beef marketing channel. The results show price transmission is bidirectional, determined through interaction between the different stages, and price adjustment is asymmetric with respect to both speed and magnitude. The results reveal a differential impact of the exogenous shock on producers and retailers, which leads to widening of price margins and points to imperfect price transmission, specifically at the retail level, with consequences for the efficiency and equity of the marketing channel. [EconLit citations: Q11, Q13]. © 2007 Wiley Periodicals, Inc. Agribusiness 23: 333–348, 2007.
Nonhomogeneous products and the law of one price
Authors: Spreen Thomas H. , Kilmer Richard L. , Pitta Carlos R. 
Published: July 2007

AbstractLaw of One Price (LOP) is important in the theory of international trade. It is important in LOP studies to have data that accurately represents homogeneous products (i.e., the product in one country has the same product characteristics as the product in another country). We present a theoretical model that determines fresh grapefruit prices Free on Board (FOB) at the packinghouse. The first order conditions show that the FOB packinghouse prices are equal for products with the same product characteristics. The theoretical conditions show a difference in FOB prices when the product characteristics are different. The product characteristics that are varied include packing costs and pack‐out rates. The results from a nonlinear programming optimization routine demonstrates the importance of using data that accurately represents homogeneous products for LOP studies. Different packing costs and pack‐out percentages are shown to cause different FOB packinghouse prices for fresh grapefruit destined for domestic and export markets. [JEL Classification: Q11, Q13, F14]. © 2007 Wiley Periodicals, Inc. Agribusiness 23: 407–420, 2007.
The economic nature of network capital in B2B transactions
Authors: Wilson Paul N. 
Published: July 2007

AbstractSocial scientists, including numerous economists, have explored the incidence and importance of social capital embedded networks as a governance mechanism in business operations. The buyer‐seller dyads represented by 12 large‐scale dairies and 7 feed suppliers were studied to contribute to our understanding of network capital in business‐to‐business (B2B) transactions. A high incidence of institutional and personal trust was found in these buyer‐seller networks. Trust facilitates economic exchange through uncertainty management, information sharing, and time savings. [L140, Q120]. © 2007 Wiley Periodicals, Inc. Agribusiness 23: 435–448, 2007.
Job stress and other working conditions: Relationships with smoking behaviors in a representative sample of working Australians
Authors: Radi Samia , Ostry Aleck , LaMontagne Anthony D. 
Published: July 2007

AbstractObjectivesTo assess the relationships between current smoking status and psychosocial working conditions.MethodsA cross‐sectional population‐based telephone survey was conducted (66% response rate, N = 1,101). Job stress was measured using the demand/control, effort/reward imbalance (ERI), and job pressure models. Multiple regression modelling was conducted for smoking status (current versus non‐smokers, and a more restricted analysis of current versus former‐smokers) and daily smoking intensity outcomes in relation to job stress measures, working hours, shift work, and other independent variables.ResultsAfter adjustment for age, education, martial status, and hostility, high job strain was positively associated with current smoking in men only. Employment in active jobs was associated with decreased odds of smoking among women only. High strain jobs were associated with decreased odds of current smoking compared to former smoking in women. In men, extreme and moderate job pressure were related to current smoking compared to current non‐smoking, and moderate job pressure was associated with current smoking compared with former smokers. Other working conditions associated with smoking were excessive working hours in men and physical demand in women. Daily smoking intensity in current smokers was associated with high psychological demand and with ERI in women.ConclusionsThese results suggest that job stress is related to smoking status at the population level, with different patterns in men and women. Am. J. Ind. Med. 50:584–596, 2007. © 2007 Wiley‐Liss, Inc.
Occupational risk factors for prostate cancer
Authors: Sass‐Kortsak Andrea M. , Purdham James T. , Kreiger Nancy , Darlington Gerarda , Lightfoot Nancy E. 
Published: July 2007

AbstractBackgroundOccupational risk factors for prostate cancer have been investigated with inconsistent findings.MethodsThis was a population‐based case‐control study of men in Northeastern Ontario, Canada. Cases (n = 760) were from the Ontario Cancer Registry, 50 to 84 years old, and diagnosed with prostate cancer between 1995 and 1998. Age‐frequency matched controls (n = 1,632) were obtained from telephone listings. A questionnaire yielded information on occupational history and self‐reported exposures to a list of occupational hazards. Exposures to these hazards were assessed by an occupational hygienist.ResultsAn odds ratio estimate (OR) of 1.21 (95 percent confidence interval (% CI) 1.01, 1.46) was found for employment in trades, transport and equipment operators and related occupations, possibly related to exposure to whole‐body vibration (OR = 1.38, 95% CI 1.07, 1.78). For the highest quartile of lifetime cumulative workplace physical activity an OR of 1.33 (95% CI 1.02, 1.74) was found. No statistically significant associations were found for any other occupational category or exposure.ConclusionsThis study does not provide strong evidence for significant occupational risk factors for prostate cancer. However, whole‐body vibration exposures, as well as physical activity, may be worth pursuing in future occupational studies. Am. J. Ind. Med. 50:568–576, 2007. © 2007 Wiley‐Liss, Inc.
Effects of postextrusion conditions on the morphology of foamed high‐density polyethylene/polypropylene blends
Authors: Zepeda Sahagún C. , González Núñez R. , Rodrigue D. 
Published: July 2007

AbstractThe effects of postextrusion conditions (i.e., the draw ratio) were studied to control the cellular structure of extruded foams based on polymer blends. High‐density polyethylene and polypropylene were foamed with azodicarbonamide as a chemical blowing agent, zinc oxide as an accelerator, and Kraton D1102 as a compatibilizer. The deformation of the cellular structure and dispersed phase particles was measured with micrographs in both longitudinal and transversal directions to obtain a full three‐dimensional picture of the foam morphology. A simple model of the cellular structure is presented to predict cell deformation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Surface nanaostructure evolution of functionalized polypropylene fibers
Authors: Wei Qufu , Wang Yingying , Wang Xueqian , Huang Fenglin , Yang Shengwei 
Published: July 2007

AbstractIt is well‐known that fiber surface characteristics affect friction, wetting, conductivity, and other performance properties. This paper reports the evolution of the surface nanostructures of meltblown polypropylene (PP) fibers during the process of plasma treatment followed by copper (Cu) sputter coating. The effects of plasma treatment and Cu sputter coating on the surface morphology, chemistry, and properties of the fibers were characterized using scanning probe microscope (SPM), environmental scanning electron microscopy (ESEM), and electrical analysis. The atomic force mode (AFM) and lateral force mode (LFM) in the SPM were used to scan the fiber surface. AFM observations revealed the evolution of the surface morphology formed by surface treatment. The LFM images also indicated the change in surface nanomechanical behavior. A full energy dispersive X‐ray analysis (EDX) mounted on the ESEM was used to examine the change in the chemical compositions of the functional surfaces. The electrical properties of the functionalized materials were analyzed using electrical resistance test. The Cu sputter coating significantly altered the surface conductivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007