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Constructal optimization of a vertical insulating wall based on a complex objective combining heat flow and strength

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Science China(Technological Sciences) 2010年第8期53卷 2278-2290页

作者： XIE ZhiHui,CHEN LinGen &SUN FengRui Postgraduate School,naval University of Engineering,Wuhan 430033,China Postgraduate School Naval University of Engineering Wuhan China

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 *** 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 *** 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)*** 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 *** constructal optimization with coequal attention to heat flow and strength and the corresponding results are discussed in *** optimal structure design and the corresponding performance analyses under various environmental conditions of application are *** the change of environment is greater and the total Rayleigh number is bigger,the insulating wall with large number of cavities should be *** the total Rayleigh number is small,the better performance can be obtained by reasonably employing the insulating wall with small number of *** complex function has better selfadaptability,and the results in the recent literature are special cases of this paper.

关键词： constructal theory insulating wall multidiscipline generalized thermodynamic optimization

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Constructal optimization of discrete and continuous-variable cross-section conducting path based on entransy dissipation rate minimization

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Science China(Technological Sciences) 2010年第6期53卷 1666-1677页

作者： WEI ShuHuan,CHEN LinGen & SUN FengRui Postgraduate School,naval University of Engineering,Wuhan 430033,China Postgraduate School Naval University of Engineering Wuhan China

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 *** 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 *** 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 *** 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.

关键词： constructal theory entransy entransy dissipation area-point conduction generalized thermodynamic optimization

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Thermodynamic characteristics of a Brownian heat pump in a spatially periodic temperature field

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Science China(Physics,Mechanics & Astronomy) 2010年第5期53卷 876-885页

作者： DING ZeMin,CHEN LinGen & SUN FengRui Postgraduate School,naval University of Engineering,Wuhan 430033,China Postgraduate School Naval University of Engineering Wuhan China

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 *** heat flows driven by both potential and kinetic energies are taken into *** 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 *** 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 *** study has also investigated the influences of the operating parameters,*** 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 *** effective regions of external force and barrier height of the potential in which the Brownian motor can operates as a heat pump are *** 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.

关键词： Brownian heat pump COP heating load heat flow performance characteristics finite time thermodynamics

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Nonlinear analysis of slow drift extreme responses of a compliant offshore structure

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Acta Mechanica Sinica 2009年第5期25卷 651-657页

作者： Yingguang Wang Jiahua Tan School of naval Architecture, Ocean and Civil Engineering,Shanghai Jiao Tong University, 200240 Shanghai, China School of naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai China

This paper first demonstrates that the accuracy and efficiency of the method of numerical simulation often used is not very high in predicting the slow drift surge extreme responses of a compliant offshore structure. Next, the slow drift surge extreme responses of the structure are analyzed via the path integral solution racy and efficiency of the PIS （PIS） method, and the accumethod is found to be higher than those of the numerical simulation method. A compound PIS （CPIS） method is first proposed in this article to further improve the efficiency of the path integral solution method, and the accuracy and efficiency of the CPIS method is validated.

关键词： Compliant offshore simulation Path integral solution solution structure Numerical Compound path integral

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SHIP HYDRODYNAMICS BASIC RESEARCH IN THE UNITED STATES

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Journal of Hydrodynamics 1995年第4期7卷 22-34页

作者： Edwin P. Rood(Mechanics and Engergy Conversion (333), Office of naval Research Arlington VA 22217 USA) Office of naval Research Arlington Arlington United States

An overview of basic research on ship hydrodynamics in the United States ispresented. The focus is on leading edge research of high scientific interest bUt with ship hydrodynamics applicability. The research topic areas are briefly discussed, representative highlights from recent research are presented, and scientific hurdles to improved ship hydrodynamics technology are delineated. The purpose of the paper is to stimulate international cooperation in solving the basic research problems of common interest to all hydrodynamicists.

关键词： ship performance ship hydrodynamics computational fluid dynamics

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BROADBAND ROTOR NOISE PREDICTION BASED ON A NEW FREQUENCY-DOMAIN FOUMULATION

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Journal of Hydrodynamics 2010年第3期22卷 387-392页

作者： XIE Jian-bo ZHOU Qi-dou FANG Bin Department of naval Architecture and Ocean Engineering Naval University of Engineering Wuhan 430033China

This article studies the broadband noise of a rotor in upstream turbulence. A numerical approach is proposed, based on frequency domain, for predicting rotor broadband noise which requires the aerodynamic sources to be integrated over the actual blade surface rather than over the mean-chord surface. The prediction of the radiated rotor broadband noise due to turbulence is made This method is validated through a comparison between numerical predictions and measured data, with a reasonable agreement. Noise level directivity shows that the main lobe is located along the rotor axis, while the minimum noise occurs in the direction vertical to the rotor axis.

关键词： acoustics broadband noise rotor frequency-domain formulation

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Noise reduction method for nonlinear signal based on maximum variance unfolding and its application to fault diagnosis

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Science China(Technological Sciences) 2010年第8期53卷 2122-2128页

作者： ZHANG Yun &LI BenWei Department of Airborne Vehicle Engineering,naval Aeronautical Engineering Institute,Yantai 264001,China Department of Airborne Vehicle Engineering Naval Aeronautical Engineering Institute Yantai China

A new noise reduction method for nonlinear signal based on maximum variance unfolding(MVU)is *** noisy sig- nal is firstly embedded into a high-dimensional phase space based on phase space reconstruction theory,and then the manifold learning algorithm MVU is used to perform nonlinear dimensionality reduction on the data of phase space in order to separate low-dimensional manifold representing the attractor from noise ***,the noise-reduced signal is obtained through reconstructing the low-dimensional *** simulation results of Lorenz system show that the proposed MVU-based noise reduction method outperforms the KPCA-based method and has the advantages of simple parameter estimation and low parameter *** proposed method is applied to fault detection of a vibration signal from rotor-stator of aero engine with slight rubbing *** denoised results show that the slight rubbing features overwhelmed by noise can be effectively extracted by the proposed noise reduction method.

关键词： nonlinear noise reduction manifold learning maximum variance unfolding fault diagnosis

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APPLICATION OF COMPUTER GRAPHICS IN MARTENSITIC TRANSFORMATION

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Acta Metallurgica Sinica(English Letters) 1994年第2期7卷 103-106页

作者： Zhou JianqiSouthern naval Unit of Institute of naval Technical Equipment in Zhanjiang Manuscript received 18 April, 1994

This paper discuss the stereographic method of martensitic transformation (MT)in the view of computer graphics (CG) and programs are programmed to realize this method. Habit plane resulting from the programs agrees with that of numerical analysis in terms of the lattice parameters of austenite and martensite and shear mechanism supposed in Fe-22%Ni-0.8%C alloy, so does orientation relationships.

关键词： stereograpllic projection martensitic transformation computer graphics

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MOLECULAR DYNAMICS SIMULATION OF INTERFACIAL DEFECTS WITH MODIFIED POTENTIAL BASED ON THE FIRST-PRINCIPLE

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Acta Mechanica Solida Sinica 2010年第5期23卷 400-406页

作者： Dongwei Ren Jinquan Xu 1(School of naval Architecture and Civil Engineering,Shanghai Jiaotong University,Shanghai 200240,China) School of naval Architecture and Civil Engineering Shanghai Jiaotong University Shanghai China

The interfacial molecular structure of materials with different lattice constants is simulated by using the method of molecular dynamics （MD）. Potential of modified analytical embedded atom method （MAEAM） is used for nominterfacial atoms. To simulate the state of interracial atoms, further modifications are applied to the MAEAM potential based on the first- principle simulation results. It is concluded that a small change of potential may greatly influence the interfacial molecular structure. Void and diffusions can be observed in the simulation results. It is also found that the pre-existed dot defects before bonding can decrease the number of interfacial defects greatly, thereby, can increase the strength of the interface.

关键词： molecular dynamics interface defect potential first-principle

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On a Delay Reaction-Diffusion Difference Equation of Neutral Type

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Acta Mathematica Sinica,English Series 2002年第4期18卷 755-764页

作者： Bao SHI Department of Basic Sciences, naval Aeronautical Engineering Academy. Yantai 264001. P. R. China Department of Basic Sciences Naval Aeronautical Engineering Academy Yantai P. R. China

In this paper, we first consider a delay difference equation of neutral type of the form: Δ(y_n+py_(n-k))+q_ny_(n-)=0 for n∈Z^+(0) (1*) and give a different condition from that of Yu and Wang (Funkcial Ekvac, 1994, 37(2): 241 248) to guarantee that every non-oscillatory solution of (1~*) with p=1 tends to zero as n→∞ Moreover, we consider a delay reaction-diffusion difference equation of neutral type of the form: Δ_1(u_(n,m)+pu_(n-k,m)+q_(n,m)u_(n-m)=a^2Δ_2~2u_(n+1,m-1) for (n,m)∈Z^+(0)×Ω. (2*) study various casks of p in the neutral term and obtain that if p≥-1 then every non-oscillatory solution of (2~*) tends uniformly in m∈Ω to zero as n→∞: if p=-1 then every solution of (2~*) oscillates and if p<-1 then every non-oscillatory solution of (2~*) goes uniformly in m∈Ω to infinity or minus infinity as n→∞ under some hypotheses.

关键词： Delay reaction-diffusion difference equations Nentral type Asymptotic behavior Oscillation

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