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A PERTURBATION TECHNIQUE FOR PARAMETER-IDENTIFICATION IN distributed STRUCTURES

APPLIED MATHEMATICAL MODELLING 1988年第2期12卷 167-174页

作者： MEIROVITCH, L NORRIS, MA Department of Engineering Science and Mechanics Virginia Polytechnic Institute and State University Blacksburg VA 24061 USA

Structures can be regarded as distributed-parameter systems characterized by mass, damping, and stiffness distributions. A perturbation technique converging iteratively to the parameter distributions is presented. The... 详细信息

关键词： parameter identification distributed parameters system identification

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Estimating optimal open-loop controls for industrial batch heating plant

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE 2000年第8期214卷 1079-1097页

作者： Ford, J Griffiths, AJ Brandon, JA Cardiff Univ Cardiff Sch Engn Div Mech Engn & Energy Studies Cardiff CF2 1XH S Glam Wales

A mathematical model of a gas-fired heater is used to estimate fuel input trajectories that minimize fuel consumption. The model has distributed parameters and an active surface temperature constraint. Optimal control theory is used to establish a two-point boundary value problem that is solved by a combination of shooting and relaxation. The shooting algorithm is an extension of the algorithm previously reported by the same authors [3]. The relaxation algorithm is based on a method for inverting a sparse band diagonal matrix. The calculations confirm that as the time available to warm a batch plant increases so the amount of fuel necessary for the task decreases.

关键词： Pontryagin optimal control two-point boundary value problem shooting relaxation furnace modelling distributed parameters active state constraints fuel minimization steel reheating

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Non-linearity and heterogeneity in modeling of population dynamics

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MATHEMATICAL BIOSCIENCES 2014年 258卷 85-92页

作者： Karev, Georgy P. NIH Natl Ctr Biotechnol Informat Bethesda MD 20894 USA

The study of population growth reveals that the behaviors that follow the power law appear in numerous biological, demographical, ecological, physical and other contexts. Parabolic models appear to be realistic approximations of real-life replicator systems, while hyperbolic models were successfully applied to problems of global demography and appear relevant in quasispecies and hypercycle modeling. Nevertheless, it is not always clear why non-exponential growth is observed empirically and what possible origins of the non-exponential models are. In this paper the power equation is considered within the frameworks of inhomogeneous population models;it is proven that any power equation describes the total population size of a frequency-dependent model with Gamma-distributed Malthusian parameter. Additionally, any super-exponential equation describes the dynamics of inhomogeneous Malthusian density-dependent population model. All statistical characteristics of the underlying inhomogeneous models are computed explicitly. The results of this analysis show that population heterogeneity can be a reasonable explanation for power law accurately describing total population growth. (C) 2014 Elsevier Inc. All rights reserved.

关键词： Non-exponential growth distributed parameters Heterogeneous population Prebiological evolution

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Average power-handling capability of the signal line in coplanar waveguides on polyimide and GaAs substrates including the irregular line edge shape effects

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INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING 2005年第2期15卷 156-163页

作者： Yin, WY Zhang, YJ Dong, XT Gan, YB Natl Univ Singapore Temasek Labs Singapore 119260 Singapore Inst High Performance Comp Singapore Singapore

The average power-handling capability (APHC) of the signal line in finite-ground coplanar waveguides (FGCPWs) on polyimide and GaAs substrates is evaluated in this paper. In our approach, the ohmic loss of metal lines is characterized in different ways, and the effects of an irregular edge shape are also considered. The rise in temperature of the signal line is determined by single- and double-layer thermal models, with the temperature-dependent properties of the thermal conductivity of GaAs material treated appropriately. Parametric studies are carried out to investigate the overall effects of signal-line width, thickness, conductivity, edge-shape angle, and polyimide thickness on APHC. Some possible ways to enhance the APHC of these FGCPWs are also proposed. (c) 2005 Wiley Periodicals, Inc.

关键词： attenuation average power handling capability (APHC) distributed parameters finite-ground coplanar waveguides (FGCPWs) polyimide and GaAs thermal model

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A distributed parameter identification problem in neuronal cable theory models

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MATHEMATICAL BIOSCIENCES 2005年第1期194卷 1-19页

作者： Bell, J Craciun, G Ohio State Univ Math Biosci Inst Columbus OH 43210 USA Univ Maryland Baltimore Cty Dept Math & Stat Baltimore MD 21250 USA

Dendritic and axonal processes of nerve cells, along with the soma itself, have membranes with spatially distributed densities of ionic channels of various kinds. These ionic channels play a major role in characterizing the types of excitable responses expected of the cell type. These densities are usually represented as constant parameters in neural models because of the difficulty in experimentally estimating them. However, through microelectrode measurements and selective ion staining techniques, it is known that ion channels are non-uniformly spatially distributed. This paper presents a non-optimization approach to recovering a single spatially non-uniform ion density through use of temporal data that can be gotten from recording microelectrode measurements at the ends of a neural fiber segment of interest. The numerical approach is first applied to a linear cable model and a transformed version of the linear model that has closed-form solutions. Then the numerical method is shown to be applicable to non-linear nerve models by showing it can recover the potassium conductance in the Morris-Lecar model for barnacle muscle, and recover the spine density in a continuous dendritic spine model by Baer and Rinzel. (c) 2004 Published by Elsevier Inc.

关键词： cable theory inverse problems ion channel density distributed parameters variable conductance Morris-Lecar model

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Theory of Doubly-Shielded Coupled Lines for Directional Couplers of Various Directivity Types With Impedance Transformation

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 2023年第5期71卷 2104-2117页

作者： Sychev, Aleksandr N. Bondar, Vladislav A. Dagba, Kezhik B. -B. Stepanyuga, Anton I. Rudyi, Nickolay Y. Tomsk State Univ Control Syst & Radioelect TUSUR Dept Comp Syst Tomsk Russia

Asymmetric coupled lines (CLs) with double shielding in an inhomogeneous dielectric medium are studied. They have specific properties that allow the creation of impedance-transforming directional couplers with a given directivity type. The proposed models and synthesis techniques take into account both electric asymmetry and dielectric inhomogeneity. Numerical simulations and measurements prove the correctness of the general theory, and the possibility of creating co-, contra-, and trans-directional couplers with impedance-transforming and phase-shifting properties. The results will be useful for finding new design solutions for next-generation microwave circuits.

关键词： Coupled lines (CLs) coupling coefficient directional coupler distributed parameters double shielding impedance transformer inhomogeneous dielectric microwave hybrid modal parameters

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Modelling of heat and flow phenomena occuring in waterwall tubes of boilers for supercritical steam parameters

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ARCHIVES OF THERMODYNAMICS 2010年第3期31卷 19-36页

作者： Zima, Wieslaw Gradziel, Slawomir Cebula, Artur Cracow Univ Technol Dept Thermal Power Engn Al Jana Pawla 2-37 PL-31864 Krakow Poland

In this paper a mathematical model enabling the analysis of the heat-flow phenomena occurring in the waterwalls of the combustion chambers of the boilers for supercritical parameters is proposed. It is a one-dimensional model with distributed parameters based on the solution of equations describing the conservation laws of mass, momentum, and energy. The purpose of the numerical calculations is to determine the distributions of the fluid enthalpy and the temperature of the waterwall pipes. This temperature should not exceed the calculation temperature for particular category of steel. The derived differential equations are solved using two methods: with the use of the implicit difference scheme, in which the mesh with regular nodes was applied, and using the Runge-Kutta method. The temperature distribution of the waterwall pipes is determined using the CFD. All thermophysical properties of the fluid and waterwall pipes are computed in real-time. The time-spatial heat transfer coefficient distribution is also computed in the on-line mode. The heat calculations for the combustion chamber are carried out with the use of the zone method, thus the thermal load distribution of the waterwalls is known. The time needed for the computations is of great importance when taking into consideration calculations carried out in the on-line mode. A correctly solved one-dimensional model ensures the appropriately short computational time.

关键词： Waterwalls Supercritical parameters Mathematical model distributed parameters Implicit difference scheme

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A structured population modeling framework for quantifying and predicting gene expression noise in flow cytometry data

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APPLIED MATHEMATICS LETTERS 2013年第7期26卷 794-798页

作者： Flores, Kevin B. N Carolina State Univ Dept Math Ctr Res Sci Computat Raleigh NC 27695 USA

We formulated a structured population model with distributed parameters to identify mechanisms that contribute to gene expression noise in time-dependent flow cytometry data. The model was validated using cell population-level gene expression data from two experiments with synthetically engineered eukaryotic cells. Our model captures the qualitative noise features of both experiments and accurately fit the data from the first experiment. Our results suggest that cellular switching between high and low expression states and transcriptional re-initiation are important factors needed to accurately describe gene expression noise with a structured population model. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Structured population models distributed parameters Gene regulatory networks Gene expression noise Synthetic biology

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Average power handling capability of finite-ground thin-film microstrip lines over ultra-wide frequency ranges

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IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS 2005年第10期15卷 715-717页

作者： Yin, WY Dong, XT Mao, JF Li, LW Shanghai Jiao Tong Univ Sch Elect Informat & Elect Engn Shanghai 200030 Peoples R China Natl Univ Singapore Dept Elect & Comp Engn Singapore 119260 Singapore

Based on the distributed parameters extracted and the thermal model proposed to calculate the rise in temperature, the average power handling capabilities (APHCs) of finite-ground thin-film microstrip lines (TFMLs) on Benzocyclobutene (BCB) and polyimide films over ultra-wide frequency ranges are investigated. Numerical results are given to show the enhancement in APHCs achieved by choosing appropriate metallization conductivity and thickness, BCB thermal conductivity, and polyimide thickness etc. It is believed that the proposed approach is useful in the design of practical TFML circuits.

关键词： attenuation constant average power handling capability (APHC) benzocyclobutene (BCB) distributed parameters finite-ground thin-film microstrip lines (FG-TFMLs) thermal conductivity

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The attenuation and slow-wave characteristics of an inverted embedded (IEM) metal-insulator semiconductor (MIS) microstrip line

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2004年第5期41卷 366-369页

作者： Yin, WY Dong, XT Natl Univ Singapore Temasek Labs Singapore 119260 Singapore

The attenuation and slow-wave characteristics in an inverted embedded metal-insulator-semiconductor (IEM-MIS) microstrip line are investigated in this paper, based on the extracted frequency-dependent distributed parameters, that is, per-unit-length series resistance and inductance, shunt capacitance, and conductance of the structure. Parametric studies are performed to show the combined effects of different parameters, such as strip thickness, width, conductivity, embedding depth, and. silicon conductivity and its thickness, on the mode attenuation constant and slow-wave factor (SWF). (C) 2004 Wiley Periodicals, Inc.

关键词： attenuation distributed parameters inverted embedded metal-insulator-semiconductor microstrip slow-wave factor (SWF)

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