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1Entransy dissipation minimization for liquid-solid phase change processes显示文摘The liquid-solid phase change process of a simple one-dimensional slab is studied in this paper.By taking entransy dissipation minimization as optimization objective,the optimal external reservoir temperature profiles are derived by using optimal control theory under the condition of a fixed freezing or melting time.The entransy dissipation corresponding to the optimal heat exchange strategies of minimum entransy dissipation is 8/9 of that corresponding to constant reservoir temperature operations,which is independent of all system parameters.The obtained results for entransy dissipation minimization are also compared with those obtained for the optimal heat exchange strategies of minimum entropy generation and constant reservoir temperature operations by numerical examples.The obtained results can provide some theoretical guidelines for the choice of optimal cooling or heating strategy in practical liquid-solid phase change processes.XIA ShaoJun,CHEN LinGen & SUN FengRui Postgraduate School,Naval University of Engineering,Wuhan 430033,China 2010Science China(Technological Sciences)2010,53,4:41
2“Volume-Point” heat conduction constructal optimization with entransy dissipation minimization objective based on rectangular element显示文摘By taking equivalent thermal resistance, which reflects the average heat conduc- tion effect and is defined based on entransy dissipation, as optimization objective, the 'volume to point' constructal problem of how to discharge the heat generated in a fixed volume to a heat sink on the border through relatively high conductive link is re-analyzed and re-optimized in this paper. The constructal shape of the control volume with the best average heat conduction effect is deduced. For the elemental area and the first order construct assembly, when the thermal current density in the high conductive link is linear with the length, the optimized shapes of assemble based on the minimization of entransy dissipation are the same as those based on minimization of maximum temperature difference, and the mean tem- perature difference is 2/3 of the maximum temperature difference. For the second and higher order construct assemblies, the thermal current densities in the high conductive link are not linear with the length, and the optimized shapes of assem- ble based on the minimization of entransy dissipation are different from those based on minimization of maximum temperature difference. For the same parame- ters, the constructs based on minimization of entransy dissipation and the con- structs based on minimization of maximum temperature difference are compared, and the results show that the constructs based on entransy dissipation can de- crease the mean temperature difference better than the constructs based on mini- mization of maximum temperature difference. But with the increase of the number of the order, the mean temperature difference does not always decrease, and there exist some fluctuations. Because the idea of entransy describes the heat transfer ability more suitably, all of the heat conduction constructal problems may be re-optimized based on it.WEI ShuHuan, CHEN LinGen & SUN FengRui Postgraduate School, Naval University of Engineering, Wuhan 430033, China 2008Science China(Technological Sciences)2008,51,8:47
3Constructal optimization of discrete and continuous-variable cross-section conducting path based on entransy dissipation rate minimization显示文摘Using constructal entransy dissipation rate minimization method based on discrete variable cross-section conducting path,constructal optimizations of elemental area with variable cross-section conducting path are performed,and the results are compared with the optimization results of elemental area with the constant cross-section conducting path.The comparison shows that the minimum mean temperature difference based on elemental area with variable cross-section conducting path increases and approaches a constant as the assembly's order increases,but the minimum mean temperature difference based on elemental area with constant cross-section conducting path decreases and approaches a constant as the assembly's order increases.The difference between them is caused by the different dimensionless mean temperature difference of the first order assembly.A universal constructal optimization method by self similar organization to improve heat transfer ability and its corresponding rule are proposed.With the constructal optimization method by self similar organization based on entransy dissipation rate minimization objective,the mean temperature difference approaches a constant as the assembly's order increases.WEI ShuHuan,CHEN LinGen & SUN FengRui Postgraduate School,Naval University of Engineering,Wuhan 430033,China 2010Science China(Technological Sciences)2010,53,6:27
4Constructal entransy dissipation rate and flow-resistance minimizations for cooling channels显示文摘Based on constructal theory,a construct of a volume that generates heat at every point and is cooled by the coolant in the constant or tapered channel is optimized by minimizing entransy dissipation rate and flow resistance.The optimal constructs of the rectangular elements with dimensionless mean thermal resistance minimization as well as the first-,secondand thirdorder assemblies with dimensionless global flow resistance minimizations are obtained respectively.The results show that both the mean temperature difference and the limiting temperature difference of rectangular elements based on EDR (entransy dissipation rate) and MTD (maximum temperature difference) minimizations respectively are almost equal.Comparing heat transfer performances from the two optimization procedures,the dimensionless global flow resistance is decreased more for the former procedure when the assembly’s order is high.It may create great superiority for constructal optimization to combine the entransy dissipation extreme principle with heat convection.XIAO QingHua,CHEN LinGen & SUN FengRui Postgraduate School,Naval University of Engineering,Wuhan 430033,China 2010Science China(Technological Sciences)2010,53,9:27
5A GENERAL CONSTITUTIVE RELATION FOR FATIGUE CRACK GROWTH ANALYSIS OF METAL STRUCTURES显示文摘Crack growth rate curves are the fundamental material property for metal structures under fatigue loading. Although there are many crack growth rate curves available in the literature, few of them showed the capability to explain various special phenomena observed in tests. A modified constitutive relation recently proposed by McEvily and his co-workers showed very promising capability. This modified constitutive relation is further generalized by (1) introducing an unstable fracture condition; (2) defining a virtual strength to replace the yield stress; and (3) defining an overload and underload parameter. The performances of this general constitutive relation for fatigue crack growth is extensively studied and it is found that this general constitutive relation is able to explain various phenomena observed with particular strong capability on load sequence effect.W.C. Cui and X.P. HuangSchool of Naval Architecture & Ocean Engineering, Shanghai Jiaotong University, Shanghai 200030, China 2003Acta Metallurgica Sinica(English Letters)2003,16,5:27
6Constructal optimization of a vertical insulating wall based on a complex objective combining heat flow and strength显示文摘For a vertical insulating wall,a product function of heat flow and strength with power weight is introduced as the complex optimization objective to compromise between insulating performance and mechanical performance.Under the global constraints of fixed external dimensions and safety requirements,the constructal optimization of the wall is carried out by taking the complex function maximization as the objective.It is shown that the maximum of the complex-objective function and its corresponding optimal internal structure design under a certain environmental condition can be obtained by allowing the internal structure of the wall to vary(evolve)freely.The validity,effectivity and applicability of the complex function are proved by the results and the power weight parameter in the range from 0.4 to 4 can compromise between the requirements of insulating and strength simultaneously and preferably.The constructal optimization with coequal attention to heat flow and strength and the corresponding results are discussed in detail.The optimal structure design and the corresponding performance analyses under various environmental conditions of application are presented.When the change of environment is greater and the total Rayleigh number is bigger,the insulating wall with large number of cavities should be employed.When the total Rayleigh number is small,the better performance can be obtained by reasonably employing the insulating wall with small number of cavities.The complex function has better selfadaptability,and the results in the recent literature are special cases of this paper.XIE ZhiHui,CHEN LinGen &SUN FengRui Postgraduate School,Naval University of Engineering,Wuhan 430033,China 2010Science China(Technological Sciences)2010,53,8:21
7Constructal optimization of twice Y-shaped assemblies of fins by taking maximum thermal resistance minimization as objective显示文摘In this paper,constructal optimization of the twice Y-shaped assemblies of fins with six freedom degrees (characteristic parameters of geometry) is performed by employing finite element method and taking dimensionless maximum thermal resistance as a performance index,and the heat transfer performance of the twice Y-shaped assemblies of fins under various conditions with different freedom degrees are analyzed. The results show that the twice assemblies can improve the heat transfer performance of Y-shaped fin remarkably,and the minimum maximum thermal resistance of the twice Y-shaped assemblies of fins decreases by 36.37% compared with that of once Y-shaped assembly of fins. It is also proved again that the larger the number of freedom degrees for evolving is,the more perfect the system performance is. The effects of different characteristic parameters of geometry on the performance of the twice Y-shaped assemblies of fins are different,one should pay different attention to these parameters in practical engineering designs. The effects of two angles on the maximum thermal resistance are larger,but the optima of the two angles are robust. The effects of two height ratios on the maximum thermal resistance are more remarkable than those of two thickness ratios.XIE ZhiHui, CHEN LinGen & SUN FengRui Postgraduate School, Naval University of Engineering, Wuhan 430033, China 2010Science China(Technological Sciences)2010,53,10:21
8Optimal paths for a light-driven engine with a linear phenomenological heat transfer law显示文摘An irreversible light-driven engine is described in this paper, in which the heat transfer between the working fluid and the environment obeys a linear phenomenological heat transfer law [ q ∝Δ(T -1)], with a working fluid composed of the bimolecular reacting system 2SO 3 F■S 2 O 6 F2. Piston trajectories maximizing work output and minimizing entropy generation are determined for such an engine with rate-dependent loss mechanisms of friction and heat leakage. The optimal control theory is applied to determine the optimal configurations of the piston motion trajectory and the fluid temperature. Numerical examples for the optimal configuration are provided, and the obtained results are compared with those derived with Newtonian heat transfer law [ q ∝Δ(T )].MA Kang, CHEN LinGen & SUN FengRui Postgraduate School, Naval University of Engineering, Wuhan 430033, China 2010Science China Chemistry2010,53,4:14
9Modeling and performance analysis of energy selective electron (ESE) engine with heat leakage and transmission probability显示文摘A model of an energy selective electron (ESE) engine with linear heat leakage and Lorentzian transmission probability is established in this paper.The expressions for the main performance parameters of the ESE engine operating as a heat engine or a refrigerator are derived by using the theory of finite time thermodynamics.The optimum performances of the ESE engine are explored and the influences of the heat leakage,the central energy level of the resonance,and the width of the resonance on the performance of the ESE engine are analyzed by using detailed numerical examples.The optimal operation regions of power output and efficiency (or cooling load and coefficient of performance (COP)) are also discussed.Moreover,the performances of the ESE engine with Lorentzian transmission probability are compared with those with rectangular transmission probability.It is shown that the power output versus efficiency (or cooling load versus COP) characteristic curves with and without heat leakage are all closed loop-shaped ones.The efficiency (or COP) of the ESE engine decreases as the heat leakage increases.It is found that as the resonance width increases,the power output and efficiency (or cooling load and COP) increase to a maximum and then decrease due to the finite range of energies which contribute positively to the power generation or refrigeration in the electron system.Especially,when heat leakage is taken into account,the characteristic curves of maximum efficiency (or maximum COP) versus half resonance width are parabolic-like ones,which are quite different from the monotonic decreasing characteristic curves obtained in previous analyses without considering heat leakage.The results obtained in this paper can provide some theoretical guidelines for the design and operation of practical electron energy conversion devices such as solid-state thermionic refrigerators.DING ZeMin,CHEN LinGen & SUN FengRui College of Naval Architecture and Power,Naval University of Engineering,Wuhan 430033,China Received December 24,2010 accepted May 30,2011 published online September 9,2011 2011Science China(Physics,Mechanics & Astronomy)2011,54,11:14
10Thermodynamic characteristics of a Brownian heat pump in a spatially periodic temperature field显示文摘This paper has studied the thermodynamic performance of a thermal Brownian heat pump,which consists of Brownian particles moving at a periodic sawtooth potential with external forces and contacting with the alternating hot and cold reservoirs along the space coordinate.The heat flows driven by both potential and kinetic energies are taken into account.The analytical expressions for the heating load,coefficient of performance(COP) and power input of the Brownian heat pump are derived and the performance characteristics are obtained by numerical calculations.It is shown that due to the heat flow via the change of kinetic energy of the particles,the Brownian heat pump is always irreversible and the COP can never attain the Carnot COP.The study has also investigated the influences of the operating parameters,i.e.the external force,barrier height of the potential,asymmetry of the sawtooth potential and temperature ratio of the heat reservoirs,on the performance of the Brownian heat pump.The effective regions of external force and barrier height of the potential in which the Brownian motor can operates as a heat pump are determined.The results show that the performance of the Brownian heat pump greatly depends on the parameters;if the parameters are properly chosen,the Brownian heat pump may be controlled to operate in the optimal regimes.DING ZeMin,CHEN LinGen & SUN FengRui Postgraduate School,Naval University of Engineering,Wuhan 430033,China 2010Science China(Physics,Mechanics & Astronomy)2010,53,5:12
11Dynamic Buckling of Elasto-Plastic Cylindrical Shells Under Axial Fluid-Solid Impact Load显示文摘- The dynamic buckling of elasto-plastic cylindrical shells under axial fluid-solid impact is investigated theoretically. A simplified liquid- gas- structure model is given to approximately imitate the problem. The basic equation of the structure is derived from a minimum principle in dynamics of elasto-plastic continua at finite deformation, and the flow theory of plasticity is employed. The liquid is incompressible and the gas is compressed adiabatically. A number of numerical results are presented and the characteristics of the buckling behavior under fluid-solid impact are illustrated.Gu Wangming and Chen Tieyun' Postdoctor, Department of Naval Architechture and Ocean Engineering, Shanghai Jiaotong University,Shanghai 200030 Professor, Department of Naval Architechture and Ocean Engineering, Shanghai Jiaotong University, Shanghai 200030 1994China Ocean Engineering1994,9,3:9
12Two New Methods for Multiattribute Decision Makings with Information Partially KnownLI Dengfeng Department of Basics, Dalian Naval Academy, Dalian 116018,Liaoning,China 1998Systems Science and Systems Engineering1998,8,1:9
13CFAR assessment of covariance matrix estimators for non-Gaussian clutter显示文摘In the non-Gaussian clutter modeled as independent and identically distributed spherically invariant random vectors, three estimators of sample covariance matrix (SCM), normalized sample covariance matrix (NSCM) and the corresponding recursive estimator (NSCM-RE) are analyzed. Based on the uniform theorem, three corresponding adaptive normalized matched filters (ANMF) are evaluated from the standpoint of constant false alarm rate (CFAR) property. The theoretical results demonstrate that the SCM-ANMF is only CFAR to the normalized clutter covariance matrix (NCCM); the NSCM-ANMF is only CFAR to the clutter power level; and the NSCM-RE-ANMF with finite number of iterations is still not CFAR to the NCCM. To ensure CFAR property of ANMF, an adaptive estimator (AE) is devised. Moreover, with AE as the initialization matrix for the iterations, the AE-RE is proposed. With finite number of iterations, the corresponding AE-REANMF guarantees CFAR property to both of the NCCM and the clutter power level. Finally, the performance assessment conducted by Monte Carlo simulation confirms the effectiveness of the proposed detectors.HE You, JIAN Tao, SU Feng, QU ChangWen & PING DianFa Research Institute of Information Fusion, Naval Aeronautical and Astronautical University, Yantai 264001, China 2010Science China(Information Sciences)2010,53,11:8
14STUDY OF TRIMARAN WAVEMAKING RESISTANCE WITH NUMERICAL CALCULATION AND EXPERIMENTS显示文摘Based on the potential flow assumption, this paper outlines the formulation of the boundary-value problem governing the steady free surface flow around a trimaran advancing at a constant forward. A Rankine panel method was developed for the solution of the problem. The side-hulls were treated as lifting bodies and circulation was introduced into the flow field to implement the asymmetrical flow around each side hull. The linearized free surface condition was used. The appropriate treatment for transom-stern ship was also discussed. Additionally, a test was performed to quantify the resistance and especially the interference between the main and side hulls. The numerical results are in good argeement with experimental data.Li Pei-yong, Qiu Yong-ming, Gu Min-tong School of Naval Architecture and Ocean Engineering, Shanghai Jiaotong University, Shanghai 200030, China 2002Journal of Hydrodynamics2002,14,2:8
15Coupled modeling of tumour angiogenesis, tumour growth,and blood perfusion显示文摘This paper proposes a more realistic mathematical simulation method to investigate the dynamic process of tumour angio-genesis by fully coupling the vessel growth,tumour growth and associated blood perfusion.The tumour growth and angiogenesis are coupled by the chemical microenvironment and the cell-matrix interaction.The haemodynamic calculation is carried out on the new vasculature,and an estimation of vessel collapse is made according to the wall shear stress criterion.The results are consistent with physiological observations,and further confirm the application of the coupled model feedback mechanism.The model is available to examine the interactions between angiogenesis and tumour growth,to study the change in the dynamic process of chemical environment and the vessel remodeling.Y.Cai,1,2 S.X.Xu,1,a) J.Wu,3 and Q.Long 2,b) 1) Department of Mechanics and Engineering Science,Fudan University,Shanghai 200433,China 2) Brunel Institute for Bioengineering,School of Engineering and Design,Brunel University,Uxbridge,Middlesex,UK 3) School of Naval Architecture,Ocean and Civil Engineering,Shanghai Jiaotong University,Shanghai 200240,China 2011Theoretical & Applied Mechanics Letters2011,1,4:8
16The sloshing of stratified liquid in a two-dimensional rectangular tank显示文摘The sloshing of inviscid liquid of stratified density in a rectangular tank is analyzed.As the flow is no longer irrotional,the governing equation is found to be quite different from the Laplace equation used for the liquid of constant density.In particular it contains terms of mixed temporal and spatial derivatives.The problem is solved based on the variable separation method and Laplace transform for the constant Vaisala-Brunt frequency.It is found that the stratification of density may have small effects on those natural frequencies associated with the constant density,but many new natural frequencies have appeared as a result of its effect.WU GuoXiong1,2 1 State Key Laboratory of Ocean Engineering,College of Naval Architecture,Ocean and Civil Engineering,Shanghai Jiao Tong University,Shanghai 200240,China 2 Department of Mechanical Engineering,University College London,Torrington Place,London WC1E 7JE,UK 2011Science China(Physics,Mechanics & Astronomy)2011,54,1:7
17Construction and characterization of an HCV-derived multi-epitope peptide antigen containing B-cell HVR1 mimotopes and T-cell conserved epitopes显示文摘Hepatitis C(HCV) genome is highly variable,particularly in the hypervariable region 1 (HVR1) of its E2 envelope gene.The variability of HCV genome has been a major obstacle for de-veloping HCV vaccines.Due to B-cell HVR1 mimotopes mimicking the antigenicity of natural HVR1 epitopes and some T-cell epitopes from the consensus sequence of HCV genes conserving among the different HCV genotypes,we synthesized an minigene of HCV-derived multi-epitope peptide an-tigen(CMEP) ,which contains 9 B-cell HVR1 mimotopes in E2,2 conserved CTL epitopes in C,1 conserved CTL epitope in NS3 and 1 conserved Th epitope in NS3.This minigene was cloned into a GST expression vector to generate a fusion protein GST-CMEP.The immunogenic properties of CEMP were characterized by HCV infected patients' sera,and found that the reactivity frequency reached 75%.The cross reactivity of anti-CEMP antibody with different natural HVR1 variants was up to 90%.Meanwhile,we constructed an HCV DNA vaccine candidate,plasmid pVAX1.0-st-CMEP carrying the recombinant gene(st) of a secretion signal peptide and PADRE universal Th cell epitope sequence in front of the CMEP minigene.Immunization of rabbits with pVAX1.0-st-CMEP resulted in the production of antibody,which was of the same cross reactivity as the fusion protein GST-CMEP.Our findings indicate that the HCV-derived multi-epitope peptide antigen in some degree possessed the characteristics of neutralizing HCV epitopes,and would be of the value as a candidate for the development of HCV vaccines.GAO Jun1,2,GONG Yuping1,ZHAO Ping1,ZHU Qing3,YANG Xiaoping1 & QI Zhongtian1 1.Department of Microbiology,Stake Key Laboratory of Medical Immunology,Second Military Medical University,Shanghai 200433,China 2.Department of Gastroenterology,Changhai Hospital,Second Military Medical University,Shanghai 200433,China 3.Department of Epidemiology,Naval Medical Research Institute,Shanghai 200433,China 2006Science China(Life Sciences)2006,49,5:7
18Rate of convergence for the Legendre pseudospectral optimal control of feedback linearizable systems显示文摘Pseudospectral (PS) computational methods for nonlinear constrained optimal control have been applied to many industrial-strength problems,notably,the recent zero-propellant-maneuvering of the international space station performed by NASA.In this paper,we prove a theorem on the rate of convergence for the optimal cost computed using a Legendre PS method.In addition to the high-order convergence rate,two theorems are proved for the existence and convergence of the approximate solutions.Relative to existing work on PS optimal control as well as some other direct computational methods,the proofs do not use necessary conditions of optimal control.Furthermore,we do not make coercivity type of assumptions.As a result,the theory does not require the local uniqueness of optimal solutions.In addition,a restrictive assumption on the cluster points of discrete solutions made in existing convergence theorems is removed.Wei KANG (Department of Applied Mathematics,Naval Postgraduate School,Monterey CA 93943,USA) 2010控制理论与应用(英文版)2010,8,4:5
19BLOCK DIAGONAL FORM AND BLOCK DIAGONAL CONTROLLER OF NONLINEAR SYSTEMS显示文摘A block diagonal form about a nonlinear system is defined. Based on the de finition, a design method ca1led block diagonal controller (BDC) is proPOsed bo feedbacklinearization. Thus, a linearization design of a class of nonlinear system can be simply re-alized. The result of design has been proved by mathematical simulation of a certain anti-ship missile.Zhao Guorong Zhang Fuen(Dept. of Automatic Control, Harbin Institute of Technology, Harbin, China, 150001)Gu Wenjing(Naval Aeronautical Engineering Academy, Yantai, Shantong, China, 264001) 1997Chinese Journal of Aeronautics1997,10,1:5
20A NOTE ON THE NARROW OPEN CHANNEL RESONANCE显示文摘A narrow open channel resonant phenomenon, newly found by the authors in corresponding numerical calculations , was proved to exist based on the method of matching asymptotic expansions for three different channel configurations. It is shown that the resonant wave numbe rk emerges around kL=nπ, n=1,2,3,…∞ with a corresponding frequency s hift, where L is the length of the channel. It is also clear that the resona nce in a narrow open channel is an essential property of a channel as long as it is uniformly narrow.Miao Guo-ping (School of Naval Architecture and Ocean Engineering, Shanghai Jiaot ong University, Shanghai 200030, China) H.Ishida, T.Saitoh (Department of Civil Engineering, Kanazawa University, Japan) 2002Journal of Hydrodynamics2002,14,1:4
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