检索结果-南通市图书馆

Thermodynamic Performance Characteristics of an Irreversible Micro-Brownian heat Engine Driven by Temperature Difference

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2010年第9期27卷 42-45页

作者：张彦平何济洲 Department of Physics Nanchang University Nanchang 330031

Based on the master equation describing the particles jump among barriers, the expressions of current, efficiency and power output of the heat engine are derived analytically. The general performance characteristic curves are plotted from the numerical calculation. It is found that the power output-efficiency curve is a loop-shaped one which is similar to the one for a real irreversible heat engine. When the heat flow via the kinetic energy is neglected, the power output-efficieney curve is an open-shaped one which is similar to the one for an endroeversible heat engine.

关键词： NONEQUILIBRIUM thermodynamics BROWNIAN motion processes heat engines TEMPERATURE effect NUMERICAL analysis heat equation FORCE & energy

VARIATIONAL DISCRETIZATION OF A CONTROL-CONSTRAINED PARABOLIC BANG-BANG OPTIMAL CONTROL PROBLEM

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2020年第1期38卷 14-40页

作者： Nikolaus von Daniels Michael Hinze Schwerpunkt Optimierung und Approximation Universitat HamburgBundesstrase 5520146 HamburgGermany

We consider a control-constrained parabolic optimal control problem without Tikhonov term in the tracking *** the numerical treatment,we use variational discretization of its Tikhonov regularization:For the state and the adjoint equation,we apply Petrov-Galerkin schemes in time and usual conforming finite elements in *** prove a-priori estimates for the error between the discretized regularized problem and the limit *** these estimates are not robust if the regularization parameter tends to zero,we establish robust estimates,which--depending on the problem's regularity——enhance the previous *** the special case of bang-bang solutions,these estimates are further improved.A numerical example confirms our analytical findings.

关键词： Optimal control heat equation Control constraints Finite elements A-priori error estimates Bang-bang controls

Integrability of det▽u and Evolutionary Wente's Problem Associated to heat Operator

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2007年第5期28卷 527-532页

作者： Sami BARAKET Makkia DAMMAK Mohamed JLELI Dong YE Departement de mathematiques Faculte des Sciences de Tunis Campus Universitaire2092 TunisTunisie. Departement de mathematiques Ecole Superieure des Sciences et Techniques de Tunis5 Avenue Taha-HusseinTunis BP 56Bab Menara 1008Tunisie. Departement de mathematiques UMR8088Universite de Cergy-Pontoise site Saint-Martin BP22295302 Cergy-Pontoise cedexFrance.

In this note,the authors resolve an evolutionary Wente's problem associated to heat equation,where the special integrability of det▽u for u∈H^1(R^2,R^2)is used.

关键词： Jacobian determinant heat equation Wente's problem

Regional constrained control problem for a class of semilinear distributed systems

在线全文

学校读者我要写书评

暂无评论

Control Theory and Technology 2018年第3期16卷 221-231页

作者： El Hassan ZERRIK Nihale EL BOUKHARI MACS team Faculty of Sciences Moulay Ismail University Meknes Morocco

The aim of this paper is to investigate a regional constrained optimal control problem for a class of semi[inear distributed systems, which are linear in the control but nonlinear in the state. For a quadratic cost functional and a closed convex set of admissible controls, the existence of an optimal control is proven, and then this is characterized for three cases of constraints. A useful algorithm is developed, and the approach is illustrated through simulations for a heat equation.

关键词： Semilinear distributed systems regional optimal control constraints heat equation

Stabilization of Coupled Schrdinger and heat equations with Boundary Coupling

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Stabilization of Coupled Schrdinger and Heat Equations wit...

ＣＯＭＰＬＥＸＩＴＹＯＦＬＡＲＧＥＴＩＭＥＢＥＨＡＶＩＯＵＲＯＦＥＶＯＬＵＴＩＯＮＥＱＵＡＴＩＯＮＳＷＩＴＨＢＯＵＮＤＥＤＤＡＴＡ

第三十届中国控制会议

作者： KRSTIC Miroslav Department of Mechanical and Aerospace Engineering University of California at San Diego

＜正＞We study stability of a Schr（o|¨）dinger equation with a collocated boundary feedback compensator in the form of a heat equation with a collocated input/output *** show that the spectrum of the closed-loop system consists only of two branches along two parabolas which are asymptotically symmetric relative to the line Reλ= -Imλ（the 135°line in the second quadrant）.The asymptotic expressions of both eigenvalues and eigenfunctions are *** Riesz basis property and exponential stability of the system are then *** we show that the semigroup,generated by the system operator, is of Gevrey classδ＞ 2.A numerical computation is presented for the distributions of the spectrum of the closed-loop system.

关键词： Schrdinger equation heat equation Boundary control Stability Spectrum Gevrey regularity

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2002年第2期23卷 293-310页

作者： J.L.VZQUEZ E.ZUAZUA Departamento de Matematicas Universidad AutonomaDepartamento de Matematica AplicadaUniversidadComplutense 28049MadridSpain28040 M

The authors study the asymptotic behaviour of solutions of the heat equation and a number of evolution equations using scaling techniques. It is proved that in the framework of bounded data stabilization need not occur and the general asymptotic behaviour is complex. This behaviour reflects for large times, even on compact sets, the complexity of the initial data at infinity.

关键词： Asymptotic behaviour Scaling Omega-limit heat equation Hyperbolic conservation laws

Depression of the Superfluid Transition Temperature in 4^He by a heat Flow

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2014年第11期31卷 94-98页

作者：尹亮林鹏祁欣 School of Science Beijing University of Chemical Technology Beijing 100029 Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190

The depression of the superfluid transition temperature Tλ in 4^He by a heat flow Q is studied. A small sealed cell with a capillary is introduced and a stable and flat superfluid transition temperature plateau is easily obtained by controlling the temperature of the variable-temperature platform and the bottom chamber of the sealed cell. Owing to the depression effect of the superfluid transition temperature by the heat flow, the heat flow through the capillary is changed by the temperature control to obtain multiple temperature plateaus of different heat flows. The thermometer self-heating effect, the residual heat leak of the 4.2K environment, the temperature difference on the He Ⅱ liquid column, the Kapiza thermal resistance between the liquid helium and the copper surface of the sealed cell, the temperature gradient of the sealed cell, the static pressure of the He Ⅱ liquid column and other factors have influence on the depression effect and the influence is analyzed in detail. Twenty experiments of the depression of the superfluid transition temperature in 4^He by heat flow are made with four sealed cells in one year. The formula of the superfluid transition temperature pressured by the heat flow is Tλ（Q） = -0.00000103Q ＋ 2.1769108, and covers the range 229 ≤Q ≤6462 μW/cm^2.

关键词： Superfluidity heat equation Helium Thermal resistance Physics research

On the ratio of different norms of caloric functions and related eigenfunctions of an integral operator

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2012年第8期55卷 1597-1612页

作者： DING YuTao 1,2,& ZHANG LiQun 1,2 1 Institute of Mathematics,Academy of Mathematics and Systems Science,Chinese Academy of Sciences,Beijing 100190,China 2 Hua Loo-Keng Key Laboratory of Mathematics,Chinese Academy of Sciences,Beijing 100190,China Institute of Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China Hua Loo-Keng Key Laboratory of Mathematics Chinese Academy of Sciences Beijing China

We investigate the ratio of L 1 and L 2 norms of the Cauchy problem solutions of heat equations with compact support initial *** related asymptotic behavior of the eigenvalues and eigenfunctions of certain integral op... 详细信息

关键词： integral operators eigenvalues heat equation

An Energy Regularization Method for the Backward Diffusion Problem and its Applications to Image Deblurring

在线全文

学校读者我要写书评

暂无评论

Communications in Computational Physics 2008年第6期4卷 177-194页

作者： Houde Han Ming Yan Chunlin Wu Department of Mathematics University of Science and Technology of ChinaHefeiAnhui 230026China.

For the backward diffusion equation,a stable discrete energy regularization algorithm is *** and uniqueness of the numerical solution are ***,the error between the solution of the given backward diffusion equation and the numerical solution via the regularization method can be *** numerical experiments illustrate the efficiency of the method,and its application in image deblurring.

关键词： Energy regularization method inverse problem heat equation backward diffusion equation image deblurring error estimate ill-posed well-posed.