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Supervision of two fundamental problems in modern fluid dynamics for sparing energy

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journal of Thermal Science 2009年第2期18卷 97-98页

作者： jürgen Zierep Institut für Strmungslehre Universitt Karlsruhe

The normal shock at a curved surface in transonic flow leads to a superdetermined boundary value problem. A bump behind the shock decreases the drag of the airfoil and reduces the necessary energy. Flows of non-Newtonian media lead in the contrary to subdetermined boundary initial problems. The energy balance for these fluids is of great interest for chemical engineering.

关键词： Transonic flow Shock at a curved wall Superdetermined problem Non- Newtonian media Subdeermined problem Energy balance.

Simulation of Dynamic 3D Crack Propagation within the Material Point Method

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Computer Modeling in Engineering & Sciences 2017年第4期113卷 389-410页

作者： Y.j.Guo j.A.Nairn Univ.of Utah Salt Lake CityUT 84112USA2119 Hillside Oak LnHoustonTX 77062USA Wood Science&Engineering Oregon State UniversityCorvallisOR 97330USA

This paper presents the principles and algorithms for simulation of dynamic crack propagation in elastic bodies by the material point method(MPM),from relatively simple two-dimensional cases to full three-dimensional,mixed-mode crack *** paper is intended to give a summary of the latest achievements on simulation of three-dimensional dynamic crack propagation,which is essentially an unexplored *** of the methodology presented in this paper to several dynamic crack propagation problems has shown that the MPM is a reliable and powerful approach for simulating three-dimensional,mixed-mode crack propagation.

关键词： Material point method (MPM) dynamic fracture crack propagation threedimensional cracks mixed-mode

Effects of rejuvenation heat treatment on microstructure and creep property of a Ni-based single crystal superalloy

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journal of Materials Science & Technology 2021年第1期60卷 206-215页

作者： K.j.Tan X.G.Wang j.j.Liang j.Meng Y.Z.Zhou X.F.Sun Superalloys Division Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Department of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

Both surface and internal microstructures of a second-generation Ni-based single crystal(SX) superalloy were studied after creep and rejuvenation heat treatment(RHT).It is indicated that the microstructures,such as the dislocation network,the γ phase and the γ' phase,can be recovered to those after the standard heat treatment(SHT).It is found that RHT affected zone(RAZ) formed at the surface is composed of theγ'-free layer,the transition layer and the recrystallization(RX),which are less than 20 μm in depth *** depth of the RAZ doesn't affect the properties of the *** morphology of γ' phase at the RAZ is related to the composition of the *** average creep life after RHT is close to the average life after *** is concluded that RHT could effectively repair SX parts and increase the total life of the sample after a damage by creep.

关键词： Superalloys Rejuvenation heat treatment Microstructure Creep property

Calculation of transient dynamic stress intensity factors at bimaterial interface cracks using a SBFEM-based frequency-domain approach

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Science China(Physics,Mechanics & Astronomy) 2008年第5期51卷 519-531页

作者： Z.j.YANG A.j.DEEKS College of Civil Engineering and Architecture Zhejiang University School of Civil and Resource Engineering University of Western Australia

A frequency-domain approach based on the semi-analytical scaled boundary finite element method(SBFEM) was developed to calculate dynamic stress intensity factors(DSIFs) at bimaterial interface cracks subjected to transient ***-cause the stress solutions of the SBFEM in the frequency domain are analytical in the radial direction,and the complex stress singularity at the bimaterial interface crack tip is explicitly represented in the stress solutions,the mixed-mode DSIFs were calculated directly by *** complex frequency-response functions of DSIFs were then used by the fast Fourier transform(FFT) and the inverse FFT to calculate time histories of DSIFs.A benchmark example was *** re-sults were obtained by modelling the example with a small number of degrees of freedom due to the semi-analytical nature of the SBFEM.

关键词： scaled boundary finite element method bimaterial interface crack frequency domain dynamic stress intensity factors fast Fourier transform

General noise support vector regression with non-constant uncertainty intervals for solar radiation prediction

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journal of Modern Power Systems and Clean Energy 2018年第2期6卷 268-280页

作者： j.PRADA j.R.DORRONSORO Universidad Autonoma de Madrid

General noise cost functions have been recently proposed for support vector regression(SVR). When applied to tasks whose underlying noise distribution is similar to the one assumed for the cost function, these models should perform better than classical -SVR. On the other hand, uncertainty estimates for SVR have received a somewhat limited attention in the literature until now and still have unaddressed problems. Keeping this in mind,three main goals are addressed here. First, we propose a framework that uses a combination of general noise SVR models with naive online R minimization algorithm(NORMA) as optimization method, and then gives nonconstant error intervals dependent upon input data aided by the use of clustering techniques. We give theoretical details required to implement this framework for Laplace, Gaussian, Beta, Weibull and Marshall–Olkin generalized exponential distributions. Second, we test the proposed framework in two real-world regression problems using data of two public competitions about solar energy. Results show the validity of our models and an improvement over classical -SVR. Finally, in accordance with the principle of reproducible research, we make sure that data and model implementations used for the experiments are easily and publicly accessible.

关键词： Support vector regression General noise model Naive online R minimization algorithm(NORMA) Uncertainty intervals Clustering Solar energy Reproducible research

Distributed Document Clustering Analysis Based on a Hybrid Method

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China Communications 2017年第2期14卷 131-142页

作者： j.E.judith j.jayakumari Noorul Islam Centre for Higher Education KumaracoilIndia

Clustering is one of the recently challenging tasks since there is an *** amount of data in scientific research and commercial applications. High quality and fast document clustering algorithms are in great demand to deal with large volume of data. The computational requirements for bringing such growing amount data to a central site for clustering are complex. The proposed algorithm uses optimal centroids for *** clustering based on Particle Swarm Optimization(PSO).PSO is used to take advantage of its global search ability to provide optimal centroids which aids in generating more compact clusters with improved accuracy. This proposed methodology utilizes Hadoop and Map Reduce framework which provides distributed storage and analysis to support data intensive distributed applications. Experiments were performed on Reuter's and RCV1 document dataset which shows an improvement in accuracy with reduced execution time.

关键词： distributed document clustering hadoop k-means PSO mapreduce

The circular dataimage, a graph for high-resolution circular-spatial data

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International journal of Digital Earth 2010年第1期3卷 47-71页

作者： William j.Morpheta jürgen Symanzik ATK Launch Systems Brigham CityUTUSA Department of Mathematics and Statistics Utah State UniversityLoganUTUSA

Vectors and periodic phenomena,*** versus time,have direction on a circular scale of 360°.An overview of existing methods for the display of circularspatial and vectorial-spatial data,such as arrow plots,is *** introduce the circular dataimage,a new type of graphic for the display of circular-spatial *** is defined by encoding direction in a spatial display by using colors from a color wheel constructed by connecting three or more two-color gradients with color continuity at the ***,image discontinuity from using a singlecolor gradient,***-red,does not ***-resolution global views of ocean wind direction are used as a running example throughout the *** and disadvantages of circular dataimages compared to arrow plots were obtained from a usability *** dataimages provide for simultaneous recognition of fine structure on a small-scale and large-scale structure on a global scale.

关键词： digital earth earth observation geo-spatial science geoinformatics visualization

Large eddy simulation of turbulent diffusion flame combustion using a conserved scalar methodology

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航空动力学报 2007年第7期22卷 1106-1117页

作者： K. Wang Z. Yang j. j. McGuirk Department of Aeronautical and Automotive EngineeringLoughborough University Loughborough Leicestershire LE11 3TU UK

The present paper describes an LES prediction of turbulent diffusion flame combustion in a simplifled axi-symmetric combustor *** calculations are carried out using a well-tested finite volume incompressible LES code which has been modified to handle variable density and reacting *** basic mixture fraction conserved scalar method *** with the chemical state relationships described by fast *** turbulence-chemistry interaction is modelled by a sub-grid PDF method and the PDF is assumed to follow a Beta-function *** LES predictions have been time-averaged over 3.5 flow-through times to generate the mean radial profiles of mixture fraction,product mass fraction,temperature,axial velocity and axial *** agreement of the LES predictions with the experimental data is good for all the above quantities at four different axial positions with largest differences at the first measurement *** LES method also provides information on the unsteady nature of turbulent diffusion *** turbulent reacting flows with large density ratio,it was found necessary to use a relaxation method in order to remove unphysical high-frequency fluctuations and to maintain numerical stability.

关键词：大涡模拟湍流扩散数量方法论弛豫法燃烧理论

Design and Robust Performance Evaluation of a Fractional Order PID Controller Applied to a DC Motor

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IEEE/CAA journal of Automatica Sinica 2017年第2期4卷 304-314页

作者： j.Viola L.Angel j.M.Sebastian Universidad Pontificia Bolivariana Universidad Politecnica de Madrid Centre for Automation and Robotics (CAR) UPM-CSIC

This paper proposes a methodology for the quantitative robustness evaluation of PID controllers employed in a DC motor. The robustness analysis is performed employing a 2~3 factorial experimental design for a fractional order proportional integral and derivative controller(FOPID), integer order proportional integral and derivative controller(IOPID)and the Skogestad internal model control controller(SIMC). The factors assumed in experiment are the presence of random noise,external disturbances in the system input and variable load. As output variables, the experimental design employs the system step response and the controller action. Practical implementation of FOPID and IOPID controllers uses the MATLAB stateflow toolbox and a NI data acquisition system. Results of the robustness analysis show that the FOPID controller has a better performance and robust stability against the experiment factors.

关键词： Factorial experimental design fractional-order PID controller robustness analysis SIMC PID controller