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Spline Function (spline + function)
Selected AbstractsAn Optimal Grey PID Control SystemIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2009Guo-Dong Li Non-member Abstract The PID control algorithm has been widely applied in many industry control system to solve efficiently the control problems of manufacturing processes. However, PID control algorithm belong to "delay control", because it functions on basis of the actions occurred in the system. Thus the control accuracy in real-time is limited. In this paper, in order to realize the accurate control in real-time, the grey model based on grey system theory is first proposed to combine with PID control to establish the control system. We define the proposed control system as grey PID control system. Then the cubic spline function is integrated into the grey model. to enhance the control accuracy of system. To further improve the performance, the particle swarm optimization (PSO) algorithm is employed to optimize the parameters of PID algorithm. Finally, we validated the effectiveness of the proposed control system by computer simulation. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Strip layer method for simulation of the three-dimensional deformations of plate and strip rollingINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3 2004Liu Hong-Min Abstract A new method,the strip layer method (SLM) is used to simulate the three-dimensional deformations of plate and strip rolling process. The rolling deformation zone is divided evenly into a number of layers along the altitudinal direction of plate or strip, every layer plate (strip) is divided into a number of streamline strip elements along metal flow traces, and the streamline strip elements are mapped onto the corresponding rectangle strip elements for analysis and computation. The longitudinal distribution model of the metal lateral displacement is constructed to be a quartic curve, its lateral distribution is expressed as the third-power spline function, and its altitudinal distribution is fitted to be a parabolic curve. Based on the flow theory of plastic mechanics, the three-dimensional deformations and stresses of the deformation zone are analysed and formulated. Compared with the streamline strip element method (SSEM), the strip layer method considers the uneven distributions of stresses and deformations along altitudinal direction, and realizes an accurate analysis and computation. The simulation examples indicate that the method and the model of this paper are in accord with facts, and provide a new reliable engineering-computation method for a three-dimensional mechanics simulation of plate and strip rolling process. Copyright © 2004 John Wiley & Sons, Ltd. [source] A spline strip kernel particle method and its application to two-dimensional elasticity problemsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2003K. M. Liew Abstract In this paper we present a novel spline strip kernel particle method (SSKPM) that has been developed for solving a class of two-dimensional (2D) elasticity problems. This new approach combines the concepts of the mesh-free methods and the spline strip method. For the interpolation of the assumed displacement field, we employed the kernel particle shape functions in the transverse direction, and the B3 -spline function in the longitudinal direction. The formulation is validated on several beam and semi-infinite plate problems. The numerical results of these test problems are then compared with the existing solutions obtained by the exact or numerical methods. From this study we conclude that the SSKPM is a potential alternative to the classical finite strip method (FSM). Copyright © 2003 John Wiley & Sons, Ltd. [source] QRS Amplitude and Shape Variability in MagnetocardiogramsPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2000MARKUS HUCK In magnetocardiography, averaging of QRS complexes is often used to improve the signal-to-noise ratio. However, averaging of QRS complexes ignores the variation in amplitude and shape of the signals caused, for example, by respiration. This may lead to suppression of signal portions within the QRS complexes. Furthermore, for inverse source, reconstructions of dipoles and of current density distributions errors in the special arrangement may occur. To overcome these problems we developed a method for separating and selective averaging QRS complexes with different shapes and amplitudes. The method is based on a spline interpolation of the QRS complex averaged by a standard procedure. This spline function then is fitted to each QRS complex in the raw data by means of nonlinear regression (Levenberg-Marquardt method). Five regression parameters are applied: a linear amplitude scaling, two parameters describing the baseline drift, a time scaling parameter, and a time shift parameter. We found that both amplitude and shape of the QRS complex are influenced by respiration. The baseline shows a weaker influence of the respiration. The regression parameters of two neighboring measurement channels correlate linearly. Thus, selective averaging of a larger number of sensors can be performed simultaneously. [source] The exposure-time-response relationship between occupational asbestos exposure and lung cancer in two German case-control studies,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2002Michael Hauptmann PhD Abstract Background Numerous studies have been carried out to evaluate the association between lung cancer and occupational asbestos exposure. However, the effects of timing of exposure have not been analyzed thoroughly. Methods Two German case-control studies with data on occupational asbestos exposure histories have been pooled. Duration of work in potentially asbestos exposed jobs and two derived weighted exposure measures are analyzed together with time since last exposure. A spline function is used to model the effect of time since exposure. Results The odds ratios (OR) and corresponding 95% confidence intervals were 1.8 (1.2, 2.7) and 2.4 (1.7, 3.4) for subjects having worked for 3 to 7 years and 8 or more years, respectively, in a job with potential asbestos exposure compared to never-exposed. Based on an evaluation of time since last exposure, the OR decreased significantly to about one-half after more than 20 years since exposure ceased. Using a spline function, applied to workers' complete exposure histories, the effect of an increment of exposure is greatest 10,15 years after that exposure was received. Conclusions In contrast to previous indications, the risk of lung cancer increases soon after asbestos exposure, with its maximum effect from 10 to 15 years after the exposure was received. Am. J. Ind. Med. 41:89,97, 2002. Published 2002 Wiley-Liss, Inc. [source] Toward a Continuous Quality Improvement Paradigm for Hemodialysis Providers with Preliminary Suggestions for Clinical Practice Monitoring and MeasurementHEMODIALYSIS INTERNATIONAL, Issue 1 2003Edmund G. Lowrie Background: Consensus processes using the clinical literature as the primary source for information generally drive projects to draft clinical practice guidelines (CPGs). Most such literature citations describe special projects that are not part of an organized quality management initiative, and the publication/review/consensus process tends to be long. This project describes an initiative to develop and explore a flexible and dedicated data-driven paradigm for deciding new CPGs that could be rapidly responsive to changing medical knowledge and practice. Methods: Candidate Clinical Practice Monitoring Measures (CPMM) were selected using a large, national database according to the natures and strengths of their associations with mortality risk among patients during 1994. Thresholds above or below which risk of death increased were evaluated for each CPMM using risk profile charts and spline functions. The fractions of patients outside of those thresholds in each dialysis unit (the %Var) were determined for the years 1993, 1994, and 1995. A standardized mortality ratio (SMR) was also determined for each year for each facility. The associations between the %Var and SMR were evaluated in several single-variable and multivariable statistical models. Results: Eleven CPMM were selected and evaluated based on their associations with death risk. These included the urea clearance x dialysis time product (Kt); the concentrations of albumin, potassium, phosphate, bicarbonate, hemoglobin, neutrophils, and lymphocytes in the blood; the body weight/height ratio; diastolic blood pressure; and vascular access type. Even though the CPMM were strongly associated with death risk among patients, the %Var were weakly and inconsistently associated with SMR among facilities. Conclusions: The paradigm was flexible, easy to implement, quickly executed, and potentially able to accommodate evolving medical practice assuming the availability of large database systems such as this. The primary associates of death risk were easily identified and the thresholds easily adopted. The SMR and %Var from the CPMM were only weakly associated, however, suggesting that one cannot be reliably predicted from the other. As such, quality management programs should likely monitor both the processes and outcomes of care among dialysis facilities. [source] Description method for spatio-temporal regions in a video and its applicationINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 5 2003Toshimitsu Kaneko Abstract A new description method for spatio-temporal regions in a video is proposed. It is efficient in terms of description data size and computational complexity under the condition that the regions in each frame can be approximated by simple figures. It approximates the object region in a frame by a simple figure such as a rectangle, an ellipse, or a polygon, and describes the coordinates of its representative points (vertices). Then, the motions of the representative points are described by polynomial spline functions to express the regions in the following frames efficiently. The proposed method is adopted in the MPEG-7 standard to provide the functionality of spatio-temporal location description. Experimental results using synthesized and real videos are presented to show the efficiency. Also, movie-centric hypermedia, a typical application of this description method, is introduced in this article. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13, 257,266, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10062 [source] Selection of locations of knots for linear splines in random regression test-day modelsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2010J. Jamrozik Summary Using spline functions (segmented polynomials) in regression models requires the knowledge of the location of the knots. Knots are the points at which independent linear segments are connected. Optimal positions of knots for linear splines of different orders were determined in this study for different scenarios, using existing estimates of covariance functions and an optimization algorithm. The traits considered were test-day milk, fat and protein yields, and somatic cell score (SCS) in the first three lactations of Canadian Holsteins. Two ranges of days in milk (from 5 to 305 and from 5 to 365) were taken into account. In addition, four different populations of Holstein cows, from Australia, Canada, Italy and New Zealand, were examined with respect to first lactation (305 days) milk only. The estimates of genetic and permanent environmental covariance functions were based on single- and multiple-trait test-day models, with Legendre polynomials of order 4 as random regressions. A differential evolution algorithm was applied to find the best location of knots for splines of orders 4 to 7 and the criterion for optimization was the goodness-of-fit of the spline covariance function. Results indicated that the optimal position of knots for linear splines differed between genetic and permanent environmental effects, as well as between traits and lactations. Different populations also exhibited different patterns of optimal knot locations. With linear splines, different positions of knots should therefore be used for different effects and traits in random regression test-day models when analysing milk production traits. [source] Estimation and Inference for a Spline-Enhanced Population Pharmacokinetic ModelBIOMETRICS, Issue 3 2002Lang Li Summary. This article is motivated by an application where subjects were dosed three times with the same drug and the drug concentration profiles appeared to be the lowest after the third dose. One possible explanation is that the pharmacokinetic (PK) parameters vary over time. Therefore, we consider population PK models with time-varying PK parameters. These time-varying PK parameters are modeled by natural cubic spline functions in the ordinary differential equations. Mean parameters, variance components, and smoothing parameters are jointly estimated by maximizing the double penalized log likelihood. Mean functions and their derivatives are obtained by the numerical solution of ordinary differential equations. The interpretation of PK parameters in the model and its flexibility are discussed. The proposed methods are illustrated by application to the data that motivated this article. The model's performance is evaluated through simulation. [source] | |||||||||||||