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distributed parameter thermal controllability: a numerical method for solving the inverse heat conduction problem

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING 2004年第7期59卷 945-961页

作者： Alaeddine, M Doumanidis, CC Tufts Univ Dept Mech Engn Medford MA 02155 USA Natl Sci Fdn Arlington VA 22230 USA

This paper addresses the inverse heat conduction problem encountered in thermal manufacturing processes. A numerical control algorithm is developed for distributed parameter conduction systems, based on Galerkin optimization of an energy index employing Green's functions. Various temperature profiles of variable complexity are studied, using the proposed technique, in order to determine the surface heat input distribution necessary to generate the desired temperature field inside a solid body. Furthermore, the effect of altering the iterative time step and duration of processing time, on the convergence of the solution generated by the aforementioned method is investigated. It is proved that despite the variations in numerical processing, the iterative technique is able to solve the problem of inverse heat conduction in the thermal processing of materials. Copyright (C) 2004 John Wiley Sons, Ltd.

关键词： distributed parameter thermal control numerical method

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distributed parameter model for computing energy dissipation in brush-type electrostatic discharges

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JOURNAL OF ELECTROSTATICS 2005年第3-4期63卷 239-247页

作者： Crager, JC Horenstein, MN Boston Univ Dept Elect & Comp Engn Boston MA 02215 USA

A distributed parameter model has been developed for estimating energy dissipation and charge transfer in electrostatic discharges from thin insulating sheets backed by a ground plane. The sheets are represented as an array of discretized elements;each assigned a capacitance and an initial surface charge. Simulations were performed by means of all equivalent two-dimensional network of resistors, capacitors, and spark gaps. Time evolution of the system was determined by ordinary circuit equations and the physics governing the breakdown of air in the gaps. The model also generates "simulated Lichtenberg figures", providing insight into the mechanism governing the complex breakdown patterns that form across insulating surfaces when these discharges occur. Experiments to assess the validity of the model are discussed. Simulation results provided by the model were found to be in good agreement with those obtained experimentally. (C) 2004 Elsevier B.V. All rights reserved.

关键词： propagating brush discharge spark energy computation distributed parameter

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distributed parameter modal filtering using smart sensors

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JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME 1996年第4期118卷 630-640页

作者： Tanaka, N Snyder, SD Hansen, CH UNIV ADELAIDE DEPT ENGN MECHADELAIDESA 5001AUSTRALIA

This paper considers the design of distributed parameter modal sensors called ''smart sensors,'' with a particular emphasis on filtering the combination of appropriately weighted vibration modes providing a specific performance index in control strategy First, with a two-dimensional distributed parameter sensor using a PVDF film, the necessary and sufficient condition for sensing the transformed modes of a structure is derived. Then by considering the practicability of the two-dimensional sensors, an alternative approach based upon one-dimensional smart sensors is presented. It is found that the latter approach holds the necessary condition for sensing the transformed mode. This problem is overcome by introducing multiple one-dimensional smart sensors. Moreover, the design procedure for the multiple one-dimensional smart sensors for measuring the transformed mode is established Finally, an experiment is conducted, demonstrating the validity of the smart sensors.

关键词： polyvinylidene fluoride performance indicators design process Sensors intelligent sensors Foot British distributed parameter Vibrations modes

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distributed parameter modeling to prevent charge cancellation for discrete thickness piezoelectric energy harvester

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SOLID-STATE ELECTRONICS 2018年 141卷 74-83页

作者： Krishnasamy, M. Qian, Feng Zuo, Lei Lenka, T. R. Natl Inst Technol Silchar Dept Elect & Commun Engn Microelect & VLSI Design Grp Silchar 788010 Assam India Virginia Tech Energy Harvesting & Mechatron Res Lab 311 Durham Hall Blacksburg VA 24061 USA

The charge cancellation due to the change of strain along single continuous piezoelectric layer can remarkably affect the performance of a cantilever based harvester. In this paper, analytical models using distributed parameters are developed with some extent of averting the charge cancellation in cantilever piezoelectric transducer where the piezoelectric layers are segmented at strain nodes of concerned vibration mode. The electrode of piezoelectric segments are parallelly connected with a single external resistive load in the 1st model (Model 1). While each bimorph piezoelectric layers are connected in parallel to a resistor to form an independent circuit in the 2nd model (Model 2). The analytical expressions of the closed-form electromechanical coupling responses in frequency domain under harmonic base excitation are derived based on the Euler-Bernoulli beam assumption for both models. The developed analytical models are validated by COMSOL and experimental results. The results demonstrate that the energy harvesting performance of the developed segmented piezoelectric layer models is better than the traditional model of continuous piezoelectric layer.

关键词： Charge cancellation distributed parameter Energy harvester Piezoelectric Segmented

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A distributed parameter MODEL PREDICTIVE CONTROL METHOD FOR FORCED AIR VENTILATION THROUGH STORED GRAIN

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APPLIED ENGINEERING IN AGRICULTURE 2014年第4期30卷 593-600页

作者： Zhou, H. Liu, J. Jayas, D. S. Wu, Z. Zhou, X. Beijing Univ Posts & Telecommun Automat Sch Beijing 100876 Peoples R China Beijing Union Univ Coll Automat Beijing Peoples R China Univ Manitoba Dept Biosyst Engn Winnipeg MB Canada Acad State Adm Grain Beijing Peoples R China

The grain temperature and moisture are non-uniformly distributed in grain stores. This article proposed a distributed parameter model predictive control (DP-MPC) method for the forced air ventilation process through stored grain. The goal of DP-MPC was to control the grain temperature and moisture and to save energy. The grain bulk was divided into different control units to consider the distribution of grain bulk characteristics. The controller was designed with a heat and mass transfer predictive model and an objective function. The objective function was solved with particle swarm optimization (PSO) algorithm. In each control cycle, one control unit was taken as the controlled objective. A control unit shift strategy was proposed to shift controlled objectives. Both simulations and experiments were carried out to validate the control effectiveness. Results showed that the proposed DP-MPC method could control the whole grain bulk temperature and moisture content and optimize the system energy consumption. The maximum grain temperature and moisture content differences between the controlled value and the set point were less than 1 degrees C and 1%, respectively. The energy consumed during ventilation with the DP-MPC was 15.5% less than that consumed during ventilation without control.

关键词： Stored grain Forced air ventilation Model predictive control Process optimization Temperature Moisture content distributed parameter

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Lining-deformation-induced modal coupling as squeal generator in a distributed parameter disc brake model

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JOURNAL OF SOUND AND VIBRATION 2002年第1期254卷 1-21页

作者： Flint, J Hultén, J Univ So Denmark Inst Appl Phys DK-5230 Odense Denmark Volvo Truck Corp SE-40508 Gothenburg Sweden

A distributed-parameter model of a disc brake is developed, which is used for simulation of friction-induced vibrations in the form of high-frequency squeal. The effect of different squeal generation mechanisms is investigated. The comparison of measured and calculated frequencies shows a good agreement and this study indicates that lining-deformation-induced modal coupling can act as a squeal generator in disc brakes. (C) 2002 Published by Elsevier Science Ltd.

关键词： generating mechanism DISC BRAKE squealing INDUCED VIBRATION distributed parameter

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A distributed parameter Maxwell-Slip Model or the Hysteresis in Piezoelectric Actuators

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IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS 2019年第9期66卷 7150-7158页

作者： Liu, Yanfang Du, Desong Qi, Naiming Zhao, Jun Harbin Inst Technol Dept Aerosp Engn Harbin 150006 Heilongjiang Peoples R China

In this paper, the Maxwell-slip model is extended to a distributed parameter Maxwell-slip (DPMS) model, and a DPMS model parameter identification process is proposed for the hysteresis in piezoelectric actuators (PEAs). This model is governed by a saturation deformation function (SDF) and a stiffness function (SF);it requires only a few parameters and can capture nonconvex hysteresis. It has a clear interpretation in the mechanical domain and provides insight into the mechanism of hysteresis generation;hence, it can predict the performance in the unidentified range. With a linear SDF, exponential, power-law, and polynomial SFs are studied for a PEA-based nanopositioning system. The normalized root-mean-square (NRMS) errors for these SFs are 0.60%, 0.43%, and 0.47%, respectively. With parameters identified from the middle hysteresis loop, the NRMS error is 0.68%. For the nonconvex hysteresis, the NRMS error is 2.78%. With compensation by DPMS models with the above three SFs, the hysteresis decreases by 86.95%, 87.13%, and 97.13%, respectively. The rate dependence of the frequency response is eliminated, and the -3dB bandwidth increases from 320 to 890 Hz.

关键词： distributed parameter hysteresis identification modeling piezoelectric actuator (PEA)

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A Karhunen-Loeve decomposition-based Wiener modeling approach for nonlinear distributed parameter processes

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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 2008年第12期47卷 4184-4192页

作者： Qi, Chenkun Li, Han-Xiong City Univ Hong Kong Dept Mfg Engn & Engn Management Kowloon Hong Kong Peoples R China

The spatio-temporal modeling problem from the input and output measurements for distributed parameter processes under unknown circumstances is investigated. The traditional Wiener modeling is extended to nonlinear distributed parameter systems with the help of the Karhunen-Loeve (KL) decomposition. The input is a finite-dimensional temporal variable, whereas the spatio-temporal output of the system is measured at a finite number of spatial locations. First, the measured output is used to construct a finite dimensional approximation of the system output which is expanded in terms of KL spatial basis functions. Subsequently, the temporal coefficients are used to identify a Wiener model. The identification algorithm is based on the least-squares estimation and the instrumental variables method. The simulations for parabolic and hyperbolic systems are presented to show the effectiveness of this spatio-temporal modeling method.

关键词： bockwurst Modeling hyperbolic systems distributed parameter systems distributed parameter output(systems)

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Online Spatiotemporal Least-Squares Support Vector Machine Modeling Approach for Time-Varying distributed parameter Processes

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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 2017年第25期56卷 7314-7321页

作者： Lu, XinJiang Yin, Feng Huang, MingHui Cent S Univ State Key Lab High Performance Complex Mfg Sch Mech & Elect Engn Changsha 410083 Hunan Peoples R China

Nonlinear and time-varying distributed parameter systems (DPSs) are challenging to accurately model due to potential spatiotemporal coupling, infinite-dimensional property, and time-varying dynamics. Although the least-squares support vector machine (LS-SVM) can effectively model lumped parameter systems, it is less effective to model the time-varying dynamics of a DPS, as it lacks the ability to incorporate time-varying spatiotemporal dynamics. Here, an online spatiotemporal LS-SUM approach is proposed to model a nonlinear and time-varying DPS. An adaptive spatial kernel function is first developed for online capture of the time-varying relationship between spatial locations. An online time coefficient model is then constructed to account for the time-varying temporal dynamics of the DPS. Combination of the adaptive spatial kernel function with the online time coefficient model allows for reconstruction of the complex DPS and ensures the model can reflect real-time spatiotemporal dynamics well. Experiments on a laboratory curing thermal process show the effectiveness of the proposed method.

关键词： digital power system time varying KERNEL FUNCTIONS Support Vector Network dynamics Nonlinear Models vector computer nonlinearity distributed parameter

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Simulation of a class of delay stochastic system with distributed parameter

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Journal of Systems Engineering and Electronics 2005年第4期16卷 843-846页

作者： Song Yanan Deng Feiqi Luo Qi Coll. of Automation Science and Engineering South China Univ. of Technology Guangzhou 510640 P. R. China

Simulation of a class of delay stochastic system with distributed parameter is discussed. Difference schemes for the numerical computation of delay stochastic system are obtained. The precision of the difference scheme and the efficiency of the difference scheme in simulation of delay stochastic system with distributed parameter are analyzed. Examples are given to illustrate the application of the method.

关键词： simulation distributed parameter delay stochastic system.

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