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Parameter Variations (parameter + variation)
Selected AbstractsA robust air-gap flux estimation for speed sensorless vector control of double-star induction machineINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 6 2004M.F. Mimouni Abstract The paper presents a new direct field-oriented control (DFOC) for double-star induction machine (DSIM) drives using the stator currents. First, we propose a new algorithm to estimate air-gap flux for speed sensorless air-gap flux orientation control. Compared to the previous DFOC schemes the new one is independent from any motor parameter variation, specially on the stator resistance. Then, the DFOC is associated with a low pass filter (LPF) to solve the dc drift problems caused by the pure integration of air-gap flux. In the present paper, the rotor resistance is estimated by an algorithm using Lyapunov theory. Good results have been obtained in the benchmark simulations. Copyright © 2004 John Wiley & Sons, Ltd. [source] Real-time identification of vehicle chassis dynamics using a novel reparameterization based on sensitivity invarianceINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 2 2004S. Brennan Abstract This work presents a novel methodology to identify model parameters using the concept of sensitivity invariance. Within many classical system representations, relationships between Bode parameter sensitivities may exist that are not explicitly accounted for by the formal system model. These relationships, called sensitivity invariances, will explicitly limit the possible parameter variation of the system model to a small subspace of the possible parameter gradients. By constraining the parameter identification or adaptation to a model structure with uncoupled parameter sensitivities, a more efficient identification can be obtained at a reduced computational and modelling cost. As illustration, an identification method of using sensitivity invariance is demonstrated on an experimental problem to identify, in real time, a time-varying tire parameter associated with the chassis dynamics of passenger vehicles at highway speeds. The results are validated with simulations as well as an experimental implementation on a research vehicle driven under changing road conditions. Copyright © 2004 John Wiley & Sons, Ltd. [source] Recursive estimation in constrained nonlinear dynamical systemsAICHE JOURNAL, Issue 3 2005Pramod Vachhani In any modern chemical plant or refinery, process operation and the quality of product depend on the reliability of data used for process monitoring and control. The task of improving the quality of data to be consistent with material and energy balances is called reconciliation. Because chemical processes often operate dynamically in nonlinear regimes, techniques such as extended-Kalman filter (EKF) and nonlinear dynamic data reconciliation (NDDR) have been developed for reconciliation. There are various issues that arise with the use of either of these techniques. EKF cannot handle inequality or equality constraints, whereas the NDDR has high computational cost. Therefore, a more efficient and robust method is required for reconciling process measurements and estimating parameters involved in nonlinear dynamic processes. Two solution techniques are presented: recursive nonlinear dynamic data reconciliation (RNDDR) and a combined predictor,corrector optimization (CPCO) method for efficient state and parameter estimation in nonlinear systems. The proposed approaches combine the efficiency of EKF and the ability of NDDR to handle algebraic inequality and equality constraints. Moreover, the CPCO technique allows deterministic parameter variation, thus relaxing another restriction of EKF where the parameter changes are modeled through a discrete stochastic equation. The proposed techniques are compared against the EKF and the NDDR formulations through simulation studies on a continuous stirred tank reactor and a polymerization reactor. In general, the RNDDR performs as well as the two traditional approaches, whereas the CPCO formulation provides more accurate results than RNDDR at a marginal increase in computational cost. © 2005 American Institute of Chemical Engineers AIChE J, 51: 946,959, 2005 [source] Robust H, glucose control in diabetes using a physiological modelAICHE JOURNAL, Issue 12 2000Robert S. Parker A robust H, controller was developed to deliver insulin via a mechanical pump in Type I diabetic patients. A fundamental nonlinear diabetic patient model was linearized and then reduced to a third-order linear form for controller synthesis. Uncertainty in the nonlinear model was characterized by up to ±40% variation in eight physiological parameters. A sensitivity analysis identified the three-parameter set having the most significant effect on glucose and insulin dynamics over the frequency range of interest , = [0.002, 0.2] (rad/min). This uncertainty was represented in the frequency domain and incorporated in the controller design. Controller performance was assessed in terms of its ability to track a normoglycemic set point (81.1 mg/dL) in response to a 50 g meal disturbance. In the nominal continuous-time case, the controller maintained glucose concentrations within ±3.3 mg/dL of set point. A controller tuned to accommodate uncertainty yielded a maximum deviation of 17.6 mg/dL for the worst-case parameter variation. [source] Informing policy for the Australian context , Costs, outcomes and cost savings of prenatal carrier screening for cystic fibrosisAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 1 2010Susannah MAXWELL Aims:, To examine the costs, outcomes and cost savings of three models of prenatal cystic fibrosis (CF) carrier screening compared to no screening from a public health sector perspective. Methods:, A decision tree was generated to estimate costs and outcomes for each screening model for a hypothetical cohort of 38 000 pregnancies. Sensitivity analysis assessed the impact of model parameter variation. Results:, Under baseline assumptions, the initial annual cost to provide a prenatal CF carrier-screening programme is Au$5.32 million, Au$3.35 million and $2.93 million for one-step, two-step simultaneous and two-step sequential screening respectively. Annual costs are significantly lower for an established programme. No screening model provides a net saving over a lifetime horizon; however, the results were sensitive to variation in lifetime cost of care, screening test costs and number of pregnancies per carrier couple. Conclusions:, Under some scenarios, prenatal CF carrier screening is cost saving to the health system; however, this is not conclusive and depends on several factors. Cost remains a potential barrier due to the substantial level of funding required in the short term. Feasibility and psychosocial, ethical and legal implications of screening need to be considered. Additionally, consultation is required with the Australian community on the acceptability and/or desire for prenatal CF carrier screening. [source] Robust parameter estimation during logistic modeling of batch and fed-batch culture kineticsBIOTECHNOLOGY PROGRESS, Issue 3 2009Chetan T. Goudar Abstract Methods for robust logistic modeling of batch and fed-batch mammalian cell cultures are presented in this study. Linearized forms of the logistic growth, logistic decline, and generalized logistic equation were derived to obtain initial estimates of the parameters by linear least squares. These initial estimates facilitated subsequent determination of refined values by nonlinear optimization using three different algorithms. Data from BHK, CHO, and hybridoma cells in batch or fed-batch cultures at volumes ranging from 100 mL,300 L were tested with the above approach and solution convergence was obtained for all three nonlinear optimization approaches for all data sets. This result, despite the sensitivity of logistic equations to parameter variation because of their exponential nature, demonstrated that robust estimation of logistic parameters was possible by this combination of linearization followed by nonlinear optimization. The approach is relatively simple and can be implemented in a spreadsheet to robustly model mammalian cell culture batch or fed-batch data. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Real-time compensation for positioning performance using on-line parameter identification and initial value compensationELECTRICAL ENGINEERING IN JAPAN, Issue 2 2010Noriaki Hirose Abstract Variations and/or uncertainties in environments of mechatronic systems, such as electrical/mechanical parameter changes and nonlinear components, generally deteriorate the motion control performance. In our research, the fast and precise position settling performance for parameter variations in positioning devices can be improved by techniques of an on-line parameter identification and an initial value compensation. The proposed technique allows the positioning systems to be adaptive and robust for unknown parameter variations. The effectiveness of the approach has been verified by numerical simulations and experiments using a prototype. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(2): 40,49, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20926 [source] Hollow Cathode Gas Flow Sputtering of NixAly Coatings on Ti-6Al-2Sn-4Zr-6Mo: Mechanical Properties and Microstructures,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Andreas Kohns A W-TiB2 -multilayer erosion resistant coating with a NixAly bond coat deposited by hollow cathode gas flow sputtering is under development for Ti6246 aero engine compressor blades. Blade vibrations in service can produce cracks in the coating propagating into the substrate and reducing the high-cycle fatigue strength of the component. It is assumed, that this effect can be diminished by adapting the mechanical and morphological properties of the NixAly bond coat. In this context, process parameter variations are performed and discussed. [source] Tests and calculations of short-circuit forces and displacements in high-voltage substations with strained conductors and droppersEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 3 2000N. Stein Forschungsgemeinschaft für Elektrische Anlagen und Stromwirtschaft FCH and DKE UK 121.2 have recently completed an extensive systematic programme of short-circuit tests on substation bus bars of stranded conductors with and without droppers. The present test series, in continuation of the former studies, comprises 100-kV and 400-kV arrangements, applying the relevant parameters of the former. Apart from other variations, different current paths were studied for the arrangements with droppers. The present paper is confined to giving a survey of the 100-kV arrangements, parameter variations, measurements and test results, as far as they presently relate to the calculation procedure oflEC, CENELEC and D/V/VDE. It is further reported on studies with the Finite-Element Method (FEM) which show a remarkable comparative accuracy. Finally, the standardized method of IEC 60865-1 and EN 60865-1 for the calculation of short-circuit tensile forces is extended onto arrangements with droppers. [source] Robust speed estimation and control of an induction motor drive based on artificial neural networksINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 5 2008Oscar Barambones Abstract In this paper, a speed estimation and control scheme of an induction motor drive based on an indirect field-oriented control is presented. On one hand, a rotor speed estimator based on an artificial neural network is proposed, and on the other hand, a control strategy based on the sliding-mode controller type is proposed. The stability analysis of the presented control scheme under parameter uncertainties and load disturbances is provided using the Lyapunov stability theory. Finally, simulated results show that the presented controller with the proposed observer provides high-performance dynamic characteristics and that this scheme is robust with respect to plant parameter variations and external load disturbances. Copyright © 2007 John Wiley & Sons, Ltd. [source] Adaptive recurrent neural network control of biological wastewater treatmentINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 2 2005Ieroham S. Baruch Three adaptive neural network control structures to regulate a biological wastewater treatment process are introduced: indirect, inverse model, and direct adaptive neural control. The objective is to keep the concentration of the recycled biomass proportional to the influent flow rate in the presence of periodically acting disturbances, process parameter variations, and measurement noise. This is achieved by the so-called Jordan Canonical Recurrent Trainable Neural Network, which is a completely parallel and parametric neural structure, permitting the use of the obtained parameters, during the learning phase, directly for control system design. Comparative simulation results confirmed the applicability of the proposed control schemes. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 173,193, 2005. [source] A new procedure for nonlinear statistical model extraction of GaAs FET-integrated circuitsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2003Francesco Centurelli Abstract A new statistical nonlinear model of GaAs FET MMICs which allows the representation of distance-dependent technological parameter variations by means of equivalent circuit parameters, and an automatic extraction procedure, are presented. The capability to reproduce statistical distribution has been successfully checked on S parameters at different distances in the 1,50 GHz frequency range. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13, 348,356, 2003. [source] Observer design with guaranteed RMS gain for discrete-time LPV systems with Markovian jumpsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2009Giuseppe C. Calafiore Abstract In this paper we consider the problem of designing state observers with guaranteed power-to-power (RMS) gain for a class of stochastic discrete-time linear systems that possess both measurable parameter variations and Markovian jumps in their dynamics. It is shown in the paper that an upper bound on the RMS gain of the observer can be characterized in terms of feasibility of a family of parameter-dependent linear matrix inequalities (LMIs). Any feasible solution to these LMIs can then be used to explicitly construct a parameter-varying jump observer that guarantees the desired performance level. This design framework is then specialized to a problem of state estimation for a linear parameter-varying plant whose state measurements are available through a lossy Bernoulli channel. Two numerical examples illustrate the results. Copyright © 2008 John Wiley & Sons, Ltd. [source] Adaptive sensorless robust control of AC drives based on sliding mode control theoryINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 9 2007O. Barambones Abstract This paper focuses in the design of a new adaptive sensorless robust control to improve the trajectory tracking performance of induction motors. The proposed design employs the so-called vector (or field oriented) control theory for the induction motor drives, being the designed control law based on an integral sliding-mode algorithm that overcomes the system uncertainties. This sliding-mode control law incorporates an adaptive switching gain in order to avoid the need of calculating an upper limit for the system uncertainties. The proposed design also includes a new method in order to estimate the rotor speed. In this method, the rotor speed estimation error is presented as a first-order simple function based on the difference between the real stator currents and the estimated stator currents. The stability analysis of the proposed controller under parameter uncertainties and load disturbances is provided using the Lyapunov stability theory. The simulated results show, on the one hand that the proposed controller with the proposed rotor speed estimator provides high-performance dynamic characteristics, and on the other hand that this scheme is robust with respect to plant parameter variations and external load disturbances. Finally, experimental results show the performance of the proposed control scheme. Copyright © 2006 John Wiley & Sons, Ltd. [source] Observer-based adaptive robust control of a class of nonlinear systems with dynamic uncertainties,INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 4 2001Bin Yao Abstract In this paper, a discontinuous projection-based adaptive robust control (ARC) scheme is constructed for a class of nonlinear systems in an extended semi-strict feedback form by incorporating a nonlinear observer and a dynamic normalization signal. The form allows for parametric uncertainties, uncertain nonlinearities, and dynamic uncertainties. The unmeasured states associated with the dynamic uncertainties are assumed to enter the system equations in an affine fashion. A novel nonlinear observer is first constructed to estimate the unmeasured states for a less conservative design. Estimation errors of dynamic uncertainties, as well as other model uncertainties, are dealt with effectively via certain robust feedback control terms for a guaranteed robust performance. In contrast with existing conservative robust adaptive control schemes, the proposed ARC method makes full use of the available structural information on the unmeasured state dynamics and the prior knowledge on the bounds of parameter variations for high performance. The resulting ARC controller achieves a prescribed output tracking transient performance and final tracking accuracy in the sense that the upper bound on the absolute value of the output tracking error over entire time-history is given and related to certain controller design parameters in a known form. Furthermore, in the absence of uncertain nonlinearities, asymptotic output tracking is also achieved. Copyright © 2001 John Wiley & Sons, Ltd. [source] Negative (and very low) thermal expansion in ReO3 from 5 to 300,KJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2009Monica Dapiaggi This paper reports the accurate measurement of the ReO3 cell parameter as a function of temperature. The thermal expansion is confirmed to be negative over most of the temperature range from 5 to 300,K. The main problems with the measurements are the very small variations (in the range of 10,5,Å) in the cell parameter at each temperature, requiring tight control of the stability and reliability of instrumental effects. In particular, achieving monochromator stability over time might be challenging with the high energy and high beam current variations of a third-generation synchrotron facility. On the other hand, such effects are usually checked by the addition of silicon as an internal standard, but the accuracy (and precision) of the published thermal expansion (which is not certified) might not be sufficient for its use when dealing with very small cell parameter variations. [source] The effect of nucleus implant parameters on the compressive mechanics of the lumbar intervertebral disc: A finite element studyJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2009Abhijeet Joshi Abstract A simplified finite element model of the human lumbar intervertebral disc was utilized for understanding nucleus pulposus implant mechanics. The model was used to assess the effect of nucleus implant parameter variations on the resulting compressive biomechanics of the lumbar anterior column unit. The effects of nucleus implant material (modulus and Poisson's ratio) and geometrical (height and diameter) parameters on the mechanical behavior of the disc were investigated. The model predicted that variations in implant modulus contribute less to the compressive disc mechanics compared to the implant geometrical parameters, for the ranges examined. It was concluded that some threshold exists for the nucleus implant modulus, below which little variations in load,displacement behavior were shown. Compressive biomechanics were highly affected by implant volume (under-filling the nucleus cavity, line-to-line fit, or over-filling the nucleus cavity) with a greater restoration of compressive mechanics observed with the over-filled implant design. This work indicated the effect of nucleus implant parameter variations on the compressive mechanics of the human lumbar intervertebral disc and importance of the "fit and fill" effect of the nuclear cavity in the restoration of the human intervertebral disc mechanics in compression. These findings may have clinical significance for nucleus implant design. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source] Rheological Characteristics of Pimento Purée: Theoretical InterpretationJOURNAL OF FOOD SCIENCE, Issue 7 2002E. Cepedaand ABSTRACT: Rheological characteristics of pimento purée were investigated at different temperatures (5 to 40 °C). The purée serum was a cloudy liquid (0to40 ,m particles) with Newtonian behavior, and flow activation energy of 25.9 kJ/ mol. The power law model was applied to fit the pseudoplastic behavior of pimento purée. The activation energy for flow, evaluated with the Arrhenius-Guzman equation, was low and depended on the variety. A modified Krieger-Dougherty model with 2 parameters was proposed to describe the effect of wet pulp fraction on the relative viscosity. In the semi-empirical model, the colloidal contribution to the viscosity at low shear rate and the parameter variations with the shear rate were considered. [source] A bandwidth-compensated transimpedance amplifier for multigigabit optical receiversMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2001F. Centurelli Abstract In this paper, a transimpedance amplifier with an automatic bandwidth compensation circuit is presented. The proposed topology includes a transimpedance amplifier which features a bandwidth control input, and a replica bias circuit to sense the active device dc parameter variations. A Monte Carlo analysis shows a 140 MHz bandwidth variation around 8.1 GHz when a ±50% variation is considered for the transconductance and threshold voltage of the HEMT devices. The same simulation shows a 490 MHz bandwidth variation if the compensation circuit is removed. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 79,81, 2001. [source] Stability of Linear Parameter Varying and Linear Switching SystemsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003Fabian Wirth We consider stability of families of linear time-varying systems, that are determined by a set of time-varying parameters which adhere to certain rules. The conditions are general enough to encompass on the one hand stability questions for systems that are frequently called linear parameter varying systems in the literature and on the other hand also linear switching systems, in which parameter variations are allowed to have discontinuities. Combinations of these two sets of assumptions are also possible within the framework studied here. Under the assumption of irreducibility of the sets of system matrices, we show how to construct parameter dependent Lyapunov functions for the systems under consideration that exactly characterize the exponential growth rate. It is clear that such Lyapunov functions do not exist in general. But every system of our class can be reduced to a finite number of subsystems for which irreducibility holds. [source] High throughput testing platform for organic Solar CellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2008Moritz K. Riede Abstract In this paper we present a high throughput testing setup for organic solar cells that is necessary for an efficient analysis of their behaviour. The setup comprises process parameter logging, automated measurement data acquisition and subsequent data management and analysis. Utilising this setup the reproducibility of solar cells and the effect of production parameter variations has been tested with a set of 360 solar cells based on the poly-3-hexylthiophene:1-(3-methoxycarbonyl)-propyl-1-1-phenyl-(6,6)C61 bulk heterojunction. Variations in power conversion efficiency between 1 and 3% were observed on varying production parameters hardly mentioned in literature. The conditions during the vacuum deposition of the aluminium cathode turned out to have a significant effect. The key solar cell parameter affecting the performance was the fill factor (FF). As such the work exemplifies the necessity for a combined approach to analyse the complex behaviour of organic solar cells. The developed high throughput testing setup provides a basis for an efficient testing of production parameter variations and materials and additionally opens the door for statistical analysis. Copyright © 2008 John Wiley & Sons, Ltd. [source] Design of electronic systems based on functional capabilityQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 1 2008James M. Gilbert Abstract An important measure of design quality is the extent to which a circuit design is able to meets its specification in the presence of component parameter variations. Of equal importance is knowing how to improve this capability most effectively. This paper presents an analysis technique and visualization method which give the designer information about design quality and possible routes to improved quality. The paper introduces two new measures of functional capability, based on the process capability measure Cpk, and shows how these may be linked to the statistical variations in individual component parameters. It then shows how this information may be used to assess the effectiveness of altering the nominal value and variability in each of the component parameters in order to improve circuit performance capability. The analysis required is straightforward and the information is presented in a clear manner which can readily be interpreted by the designer. The effectiveness of the technique has been evaluated through analysis of a number of printed circuit board level analogue and mixed signal circuits and the results of a case study are shown. Copyright © 2007 John Wiley & Sons, Ltd. [source] Robust Neural Network Controller Design For A Biaxial Servo SystemASIAN JOURNAL OF CONTROL, Issue 4 2007Chih-Hsien Yu ABSTRACT A robust control method for synchronizing a biaxial servo system motion is proposed in this paper. A new neural network based cross-coupled control and neural network techniques are used together to cancel out the skew error. In the proposed control scheme, the conventional fixed gain PID cross-coupled controller (PIDCCC) is replaced with the neural network cross-coupled controller (NNCCC) to maintain biaxial servo system synchronization motion. In addition, neural network PID position velocity and velocity controllers provide the necessary control actions to maintain synchronization while following a variable command trajectory. This scheme provides strong robustness with respect to uncertain dynamics and nonlinearities. The simulation results reveal that the proposed control structure adapts to a wide range of operating conditions and provides promising results under parameter variations and load changes. [source] MODELING OF TEXTURE EVOLUTION OF CAKES DURING STORAGEJOURNAL OF TEXTURE STUDIES, Issue 1 2010MANUEL GÓMEZ ABSTRACT The aim of this work is to model the variation of texture parameters in cakes during staling. The evolution was studied in layer cakes (cake A) and sponge cakes (cake B). The effect of storage temperature and the addition of fiber, xanthan gum (cake A) and emulsifier (cake B) were also studied. The best model to adjust the texture parameters variation during storage in both kinds of cakes was square root x (y = a + b * x1/2), except for firmness and springiness in cakes B. Firmness and springiness were adjusted the best to the linear model. In the model, y stood for the textural parameters and x for the time. a and b were related to the initial value of the studied parameter and with its change over time respectively. In both kinds of cakes, A and B, the firmness and gumminess increased, and the cohesiveness, springiness and resilience decreased, as the storage time increased. The increase in the storage temperature and the addition of fiber minimized the firmness changes in both kinds of cakes. PRACTICAL APPLICATIONS This methodology simplifies the study of cake textural parameters during storage and the result interpretation. Moreover, the correlation analysis has demonstrated that the number of textural parameters of cakes to study can be reduced. [source] Measurement based modeling and control of bimodal particle size distribution in batch emulsion polymerizationAICHE JOURNAL, Issue 8 2010Mazen Alamir Abstract In this article, a novel modeling approach is proposed for bimodal Particle Size Distribution (PSD) control in batch emulsion polymerization. The modeling approach is based on a behavioral model structure that captures the dynamics of PSD. The parameters of the resulting model can be easily identified using a limited number of experiments. The resulting model can then be incorporated in a simple learning scheme to produce a desired bimodal PSD while compensating for model mismatch and/or physical parameters variations using very simple updating rules. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Vertical dynamic response of pile in a radially heterogeneous soil layerINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2009D. Y. Yang Abstract An analysis of a pile vertical response considering soil inhomogeneity in the radial direction under dynamic loads is presented. The solution technique is based on a three-dimensional axisymmetric model, which includes the consideration of the vertical displacement of the soil. The soil domain is subdivided into a number of annular vertical zones, and the continuity of the displacements and stresses are imposed at both the interface of pile,soil and the interfaces of adjacent soil zones to establish the dynamic equilibrium equations of the pile,soil interaction. Then, the equations of each soil zone and of the pile are solved one by one to obtain the analytical and semi-analytical dynamic responses at the top of the pile in the frequency domain and time domain. Parametric studies have been performed to examine the influence of soil parameters' variations in the radial direction caused by the construction effect on the dynamic responses of pile. The results of the studies have been summarized and presented in figures to illustrate the influences of the soil parameters as they change radially. The effect of the radius of the disturbed soil zone caused by construction is also studied in this paper. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||