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Chinese Journal of Chemical Engineering 2016年第8期24卷 979-988页

作者： Yunhu Gao Zhihong Xu Kejing Wu Xiaolu Wang Zhaojun Yu Weiyang Fei Jiangsu Huayi Technology Co. Ltd. state Key Laboratory of Chemical Engineering Department of Chemical Engineering Tsinghua University China Construction Installation Engineering Co.Ltd

Accurate simulation of water distillation system for oxygen-18(18O) isotope separation is necessary to guide industrial practice, since both deuterium(D) and oxygen-18 isotope get enriched and interfere with each other. In the present work, steady-state and dynamic distillation models are established based on a classic method and a cascade distillation system with 5 towers is introduced to test the models. The theoretical expressions of separation factor αH/Dfor protium/deuterium and separation factor α^(16)O/^(18) O.for oxygen-16/oxygen-18 were derived,with the existence of deuterium and oxygen-18, respectively. The results of the steady-state simulation by the classical method proposed in the present work agreed well with the results of the lumping method. The dynamic process could be divided into 5 stages. Impressively, a peak value of product withdraw was observed before the final steady state, which was resulted from the change of ^(16)O/^(18) O separation factor and isotope distribution. An interesting low concentration zone in the towers of T2–T5 existed at the beginning of the dynamic process and it required industrial evidence.

关键词： Oxygen-18 Deuterium steady-state simulation Dynamic simulation Isotope separation

Monotonic triaxial experiments to evaluate steady-state and liquefaction susceptibility of Babolsar sand

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第10期14卷 739-750页

作者： Yaser JAFARIAN Ali GHORBANI Siavash SALAMATPOOR Sina SALAMATPOOR International Institute of Earthquake Engineering and Seismology Faculty of Engineering University of Guilan International Branch University of Guilan

In this study,drained and undrained triaxial tests under isotropic and anisotropic consolidations were conducted on reconstituted samples of Babolsar sand,which underlies a densely populated,seismic region of the southern coast of the Caspian Sea,Mazandaran,Iran.It was demonstrated that the sand experienced all possible states of liquefiable soil: flow failure,limited flow,and dilation.The steady-state and flow liquefaction lines of this sand were presented and compared with previously tested sands.It is shown that the initial stress anisotropy can affect the potential of volume change and pore pressure generation.The steady-state line(SSL),however,remains identical for the isotropically and anisotropically consolidated specimens under drained and undrained conditions.The tests data were then analyzed in order to investigate the liquefaction susceptibility of this sand in terms of parameters such as the state parameter,relative state parameter index,and lateral earth pressure ratio at failure.

关键词： Triaxial test Sand steady-state Liquefaction susceptibility

The steady-state solution of dendritic growth from the undercooled binary alloy melt with the far field flow

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Science China(Technological Sciences) 2009年第8期52卷 2280-2287页

作者： CHEN MingWen1,2, WANG ZiDong2 & XU JianJun2,3,4 1 School of Applied Sciences, University of Science and Technology Beijing, Beijing 100083, China 2 School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China 3 School of Mathematical Sciences, Nankai University, Tianjin 300071, China 4 Department of Mathematics and Statistics, McGill University, Montreal H3A 2K6, Canada School of Applied Sciences University of Science and Technology Beijing Beijing China School of Materials Science and Engineering University of Science and Technology Beijing Beijing China School of Mathematical Sciences Nankai University Tianjin China Department of Mathematics and Statistics McGill University Montreal Canada

The steady-state dendritic growth from the undercooled binary alloy melt with the far field flow is considered. By neglecting the interface energy, interface kinetics and buoyancy effects in the system, we obtaine the steady-state solution for the case of the large Schmidt number, in terms of the multiple variable expansion method. The changes of the temperature and concentration fields, the morphology of the interface, the normalization parameter and the Peclet number of the system induced by uniform external flow are derived. The results show that, compared with the system of dendritic growth from undercooled pure melt, the convective flow in the system of growth from undercooled binary alloy has stronger effects on the morphology of the interface. Nevertheless, the shape of the interface still remains nearly a paraboloid.

关键词： binary alloy melt convection dendritic growth interfaces steady-state solution multiple variable expansion method

Modified PI Controller with Improved steady-state Performance and Comparison with PR Controller on Direct Matrix Converters

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Chinese Journal of Electrical Engineering 2019年第1期5卷 53-66页

作者： Jianwei Zhang Li Li David G.Dorrell Youguang Guo College of Electric Power Inner Mongolia University of TechnologyHohhot 010051China Faculty of Engineering and IT University of Technology SydneyNSW 2007Australia Howard College Campus University of KwaZulu-NatalDurban 4000South Africa

This paper proposes a modified proportional-integral(PI)controller and compares it with a proportional-resonant(PR)controller.These controllers are tested on a three-phase direct matrix converter(MC).The modified PI controller involves current feedforward together with space vector modulation(SVM)to control the MC output currents.This controller provides extra control flexibility in terms of the current error reduction,and it gives improved steady-state tracking performance.When the coefficient of current feedforward is equal to the load resistor(K=R),the steady-state error is effectively minimized even when regulating sinusoidal variables.The total harmonic distortion is also reduced.In order to comparatively evaluate the modified PI controller,a PR controller is designed and tested.Both the modified PI and PR controllers are implemented in the natural frame(abc)in a straightforward manner.This removes the coordinate transformations that are required in the stationary(αβ)and synchronous(dq)reference frame based control strategies.In addition,both controllers can handle the unbalanced conditions.The experimental and simulation results verify the feasibility and effectiveness of the proposed controllers.

关键词： Matrix converter AC-AC conversion steady-state error PI controller PR controller

steady-state SOLUTIONS FOR A ONE-DIMENSIONAL NONISENTROPIC HYDRODYNAMIC MODEL WITH NON-CONSTANT LATTICE TEMPERATURE

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Acta Mathematica Scientia 2008年第3期28卷 479-488页

作者：黎野平 Department of Mathematics Xianning College

A one-dimensional stationary nonisentropic hydrodynamic model for semiconductor devices with non-constant lattice temperature is studied. This model consists of the equations for the electron density, the electron current density and electron temperature, coupled with the Poisson equation of the electrostatic potential in a bounded interval supplemented with proper boundary conditions. The existence and uniqueness of a strong subsonic steady-state solution with positive particle density and positive temperature is established. The proof is based on the fixed-point arguments, the Stampacchia truncation methods, and the basic energy estimates.

关键词： steady-state nonisentropic hydrodynamic model semiconductor subsonic

steady-state AND TIME-RESOLVED FLUORESCENCE STUDY OF TRIPLE EXCIPLEX IN THE SYSTEM OF POLYACENAPHTHALENE AND TEREPHTHALIC DIMETHYLESTER

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Science China Chemistry 1990年第11期33卷 1281-1289页

作者：章立民张月萍 Institute of Chemistry Academia Sinica Beijing 100080 PRC

Triple exciplex formed between polyacenaphthalene and terephthalic dimethylester （TDE） has been studied by means of the steady-state and time-resolved fluorescence spectra. The theoretical model of the triple exciplex formation for a flexible polymer chain in a dilute solution has been proposed. The fluorescence decays of the monomer, the exciplex and the triple exciplex obey a double exponential rule in the pbotophysical processes of the triple exciplex formation. The association rate constant of the exciplex formation is k3=6.0×109s-1（mol/L）-1; the association rate constant of the triple exciplex formation is k6=5.2×107s-1. A mechanism for the triple exciplex formation from the exciplex to the triple exciplex has been proved through the noncrystal films corresponding to the same concentrations of the solution systems and the fluorescence lifetimes of the intramolecular excimer.

关键词： triple exciplex steady-state time-resolved fluorescence spectra polyacenaphthalene acenaphthalene

Meshless Least-Squares Method for Solving the steady-state Heat Conduction Equation

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Tsinghua Science and Technology 2005年第1期10卷 61-66页

作者：刘岩张雄陆明万 School of Aerospace Tsinghua University Beijing 100084 China

The meshless weighted least-squares (MWLS) method is a pure meshless method that com- bines the moving least-squares approximation scheme and least-square discretization. Previous studies of the MWLS method for elastostatics and wave propagation problems have shown that the MWLS method possesses several advantages, such as high accuracy, high convergence rate, good stability, and high com- putational efficiency. In this paper, the MWLS method is extended to heat conduction problems. The MWLS computational parameters are chosen based on a thorough numerical study of 1-dimensional problems. Several 2-dimensional examples show that the MWLS method is much faster than the element free Galerkin method (EFGM), while the accuracy of the MWLS method is close to, or even better than the EFGM. These numerical results demonstrate that the MWLS method has good potential for numerical analyses of heat transfer problems.

关键词： meshless least-squares heat conduction steady-state

Energy transfer mechanism of PBS-thylakoid complexes——By deconvolution spectra and steady-state spectra (77 K) techniques

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Chinese Science Bulletin 1997年第20期42卷 1689-1693页

作者： Zhang, JM Zhao, JQ Jiang, LJ Acad Sinica Inst Photog Chem Beijing 100101 Peoples R China

Up to now, the energy transfer study has been focused on the composite of isolated PBSs, PCand APC, as well as isolated PS Ⅱ and PS Ⅰparticles with time-resolved fluorescence tech-niques. Although these studies give more important information about the energy transferamong them, they cannot explain why the energy transfer from PBS to reaction centers

关键词： PBS-thylakoid complex steady-state spectra deconvolution.

steady-state weights solution to affine projection algorithm

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控制理论与应用（英文版） 2012年第2期10卷 259-263页

作者： Yongfeng Zhi Jun Zhang Yinxue Li Department of Automatic Control Northwestern Polytechnical University Xi'an Shaanxi 710072 China

A new expression of the weights update equation for the affine projection algorithm （APA） is proposed that improves the convergence rate of an adaptive flter, particularly for highly colored input signals, and yields greater details of the internal structure. The steady-state weights solution to the APA algorithm is calculated in different step-sizes, which is significantly different from the iteration method. The weights error in steady-state is proved to be zero as the number of the input direction vector increases to infinity, ensuring that the estimated weights of the APA algorithm in steady-state are unbiased and consistent. The sensitivity of the step-size parameter for the steady-state weights is also analyzed. Simulation results show that the steady-state weights of the APA algorithm, obtained from the proposed method, are closer to the true weights than the estimated steady-state weights as determined by the traditional iteration method.

关键词： Affine projection algorithm steady-state Identification Adaptive filtering

EFFICIENT steady-state ANALYSIS METHOD FOR CLOSED-LOOP PWM SWITCHING CONVERTERS

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Journal of Pharmaceutical Analysis 2006年第1期18卷 6-12页

作者：尹有为马西奎 School of Electrical Engineering Xi'an Jiaotong UniversityXi'an 710049China

An analysis technique of steady state and stability for closed-loop PWM DC/DC switching converters is presented. Using this method, the closed-loop switching converter is transformed into an open-loop system. By means of the fact that in steady state, the two boundary values are equal in one switching period. The exponential matrix is evaluated by precise time-domain-integration method, and then the related curve between feedback duty cycle and the input one is obtained. Not only can the steady-state duty cycle be found from the curve, but also the stability and stable domain of the system. Compared with other methods, it features with simplicity and less calculation, and fit for numerical simulation and analysis for closed-loop switching converters. The simulation results of examples indicate the correctness of the presented method.

关键词： closed-loop system steady-state stability analysis switching converters