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A numerical simulation on the infrared radiation of hot exhausting nozzles with a coupled flow and heat transfer model

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Science China(Technological Sciences) 2010年第10期53卷 2699-2707页

作者： HU HaiYang1.& WANG Qiang2 1.China Academy of Aerospace Aerodynamics, beijing 1.0074, China 2 {1. of jet propulsion, beihang University, beijing 1.01.1. China 1. China Academy of Aerospace Aerodynamics Beijing 100074 China2. School of Jet Propulsion Beihang University Beijing 100191 China

A coupled model among flow field,solid temperature,species concentration and gas radiation,which was based on statistical narrow-band correlated-k model,was employed to predict the infrared radiations from hot exhausting nozzles. The parameters of narrow-band model were deduced from HITEMP line-by-line database. Several methods to increase computational efficiency and to save computational resources were employed,thus all the complicated computations could be operated on a personal computer. The predictions for three cases have been conducted to validate the accuracy of the methods mentioned above,including the temperature distribution of a water-cooling nozzle in rocket engines,the carbon dioxide absorptivity at the wavelength of 4.3 micron and the infrared radiation of a cylindrical furnace. Finally,the aerothermodynamic and infrared characteristics of two nozzles were predicted. It was shown that the infrared radiation intensity of chevron ejecting nozzle were obviously smaller than that of common axisymmetric convergent-divergent nozzle.

关键词： infrared radiation numerical simulation exhausting nozzles coupled model

Application and Comparison of SST Model in Numerical Simulation of the Axial Compressors

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Journal of Thermal Science 2010年第4期19卷 300-309页

作者： YIN Song~1.JIN Donghai~2,GUI Xingmin~3 and ZHU Fang Aero-Engines Simulation Research Center,school of {1. propulsion,beijing University of Aeronautics and Astronautics, beijing,1.01.1.China Aero-Engines Simulation Research Center School of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing China

The shear-stress transport(SST)turbulence model is incorporated into Navier-Stokes equations to simulate a turbomachinery flowfield.A staggered finite volume method is used to make the mean flow equations and turbulence model equations strongly coupled and enhance the stability of the numerical *** implicit treatment of the source terms is applied to the SST model.A steady state solution is obtained using five-stage Runge-Kutta time-stepping scheme with local time stepping and residual smoothing to accelerate convergence. The wall distance d,a key parameter in the SST model,is solved by a partial differential *** validations of the code are conducted on rotor 37,wp1. at design and off-design conditions by comparison with measurements and the Spalart-Allmaras(SA)turbulence *** flow within the tip is calculated with a multi-block grid.

关键词： SST model staggered finite volume method turbomachinery simulation multi-block grid

The regular representation and regular covariant representation of crossed products of Woronowicz C^(*)-algebras

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Science China Mathematics 2005年第9期48卷 1245-1259页

作者： ZHANG Xiaoxia~(1.2) & GUO Maozheng~(1.3) 1. school of Mathematical Sciences,Peking University,{1. 1.0871.China 2. Department of Mathematics,Yantai University,Yantai 264005,China 3. LMAM,Peking University,{1. 1.0871.China 1. school of Mathematical Sciences Peking University 100871 Beijing China 2. Department of Mathematics Yantai University 264005 Yantai China 3. LMAM Peking University 100871 Beijing China

In this paper,it is shown that the regular representation and regular covariant representation of the crossed products A×α G correspond to the twisted multiplicative unitary operators,where A is a Woronowicz C~*-algebra acted upon by a discrete group ***,it is also shown that the regular covariant C~*-algebra is the Woronowicz C~*-algebra which corresponds to a multiplicative ***,an explicit description of the multiplicative unitary operator for C(SU_q(2) )×α (?) is given in terms of those of the Woronowicz C~*-algebra C(SU_q(2) ) and the discrete group G.

关键词： multiplicative unitary operator, Woronowicz C*-algebra, crossed product.

Complex conforming Delaunay triangulation

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Science China(Information Sciences) 2010年第6期53卷 1130-1140页

作者： MENG XianHai 1. LI JiGang 1. YANG Qin 1. CAI Qiang 2 & CHEN QiMing 3 1.NLSDE, school of Computer Science and Engineering, {1. University, beijing 1.0083, China 2 school of Computer Sciences, beijing Technology and Business University, beijing 1.0037, China 3.school of Mechanical Engineering and Automation, {1. University, beijing 1.0083, China 1. NLSDE School of Computer Science and Engineering BeiHang University Beijing 100083 China2. School of Computer Sciences Beijing Technology and Business University Beijing 100037 China3. School of Mechanical Engineering and Automation BeiHang University Beijing 100083 China

A novel algorithm of conforming Delaunay triangulation for curved geometry is presented in the paper.A progress has been made for the problem puzzled Delaunay refinement where curved constraints cannot be accepted as input *** algorithm is based on a new sufficient condition for the existence of constraints in *** requires computing only the intersection between constraints and Voronoi edges or faces instead of the circum-sphere of curved *** the termination of the algorithm when small input angles exist in constraints, a weighted method is applied to ensure that the algorithm can terminate under any *** two-dimensional and three-dimensional results are also *** is shown that the algorithm has the capability of dealing with both linear and nonlinear constraints in a consistent way, without the need of maintaining triangular meshes on face constraints.

关键词： mesh generation Delaunay triangulation conforming curved constraints tetrahedralization weight

The mathematical model of wetting angle of heterogeneous nucleation

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Science China(Technological Sciences) 2004年第4期47卷 391-397页

作者： HUANG Cheng1. SONG Bo1. MAO Jinghong2 & ZHAO Pei3 1. school of Metallurgical and Ecological Engineering, University of Science and Technology {1., {1. 1.0083, China 2. school of Material Science, University of Science and Technology {1., {1. 1.0083, China 3. Central Iron and Steel Research Institute, {1. 1.0081. China 1. school of Metallurgical and Ecological Engineering University of Science and Technology Beijing 100083 Beijing China 2. school of Material Science University of Science and Technology Beijing 100083 Beijing China 3. Central Iron and Steel Research Institute 100081 Beijing China

The heterogeneous nucleation has been analyzed in terms of the thermodynamic theory, and the mathematical model of wetting angle of heterogeneous nucleation has been developed based on the dynamic requirements of hetero- and homogeneous nucleation. With the wetting angel model, the wetting angles of different catalysts in liquid iron have been calculated. The result shows that the wetting angle of most catalysts is smaller than 40, and the value of f() is far less than 1. The wetting angles of TiN, TiC and RE2O3 are smaller, while the wetting angle of MnO is bigger among the ordinary nucleation catalysts. The wetting angles calculated by this model are in agreement with the results of other research work.

关键词： heterogeneous nucleation, mathematical model, wetting angle, undercooling.

北京市体育局北京市教育委员会关于印发《北京市体育类校外培训机构设置标准(试行)》的通知(京体产业字〔2024〕1.号)

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北京市人民政府公报 2024年第21期 84-94页

作者： 1.北京市体育局 2.北京市教育委员会北京市体育局北京市教育委员会

各区体育局、各区教委,北京经济技术开发区社会事业局,燕山体育运动中心、燕山教委,各相关单位:现将《北京市体育类校外培训机构设置标准(试行)》印发给你们,请认真贯彻落实。

关键词：体育类北京经济技术开发区校外培训机构体育局设置标准体育运动中心北京市印发

A spatio-velocity model based semantic event detection algorithm for traffic surveillance video

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Science China(Technological Sciences) 2010年第S1期53卷 120-125页

作者： SHENG Hao 1.ZHAO HuiJie 1.HUANG Jian 2 & LI Na 1.1.school of Instrument Science and Opto-Electro Engineering,{1. University,beijing 1.01.1.China 2 school of Software,{1. University,beijing 1.01.1.China 1. school of Instrument Science and Opto-Electro Engineering Beijing University Beijing 100191 China 2. school of Software Beijing University Beijing 100191 China

Detection of vehicle events is a research hotspot in digital *** this paper,an approach is proposed to detect vehicle events with semantic analysis of traffic surveillance video using spatio-velocity statistic *** approach includes two successive phases:trajectory clustering and semantic events *** trajectory clustering,a statistic model of vehicle trajectories are presented,for which a spatio-velocity model is trained by analyzing the trajectories of moving vehicles in the *** on the trajectory,which represents both the position of the vehicle and its instantaneous velocity,a trajectory similarity measure is ***,an improved hierarchical clustering algorithm is adopted to cluster the trajectories according to different spatial and velocity *** each cluster,trajectories that are spatially close have similar velocities of motion and represent one type of activity *** the semantic events detection phase,statistic models of semantic regions in the scene are generated by estimating the probability density and velocity distributions of each type of activity ***,semantic events are detected by the proposed spatio-velocity statistic *** paper also presents experiments using real video sequence to verify the effectiveness of the proposed method.

关键词： trajectory clustering spatio-velocity statistic model event detection digital traffic

Similar component analysis

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Progress in Natural Science:Materials International 2006年第12期16卷 1343-1347页

作者： ZHANG Hong~1.*, WANG Xin~1. LI Junwei~2 and CAO Xianguang~1.1. Image Center, Astronautics school, {1. University, beijing 1.0083, China 2. The 207th Institute of the Second Academy of China Aerospace Science Industry Corporation, beijing 1.0854, China) [a]Image Center Astronautics School BeiHang University Beijing China [b]The 207th Institute of the Second Academy of China Aerospace Science Industry Corporation Beijing China

A new unsupervised feature extraction method called similar component analysis (SCA) is proposed in this paper. SCA method has a self-aggregation property that the data objects will move towards each other to form clusters through SCA theoretically, which can reveal the inherent pattern of similarity hidden in the dataset. The inputs of SCA are just the pairwise similarities of the dataset, which makes it easier for time series analysis due to the variable length of the time series. Our experimental results on many problems have verified the effectiveness of SCA on some engineering application.

关键词： clustering feature extraction similar component.

Calculating soil moisture by remote sensing and analyzing hydrologic cycle process in the Yellow River basin

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Science China(Technological Sciences) 2004年第z1期47卷 1-13页

作者： YANG Shengtian1.& LIU Changming1. 2 1. school of Environmental Sciences, {1. Normal University, {1. 1.0875, China 2. Institute of Geographic Science and Natural Resources Research, {1. 1.01.1. China beijing Normal Univ Sch Environm Sci Beijing 100875 Peoples R China Inst Geog Sci & Nat Resources Beijing 100101 Peoples R China

Based on the AVHRR pathfinder remote sensing data, soil moisture, precipitation and evaporation during the period of 1.82—1.98, soil moisture of all layers of soil-profile (0—1.m) in the Yellow River basin over the 1. years are calculated by the remote sensing model of calculating soil water. The Yellow River basin is divided into seven subcatchments as control sections at the location of six hydrologic stations (Lanzhou, Toudaoguai, Longmen, Sanmenxia, Huayuankou and Lijin). After calculating soil moisture and obtaining runoff data and precipitation data, the dynamical features of hydrological cycle in the Yellow River basin are analyzed for the period from 1.82 to 1.88 using water balance method. The conclusions are as follows: It is feasible to calculate the soil water on the macro-scale, in the soil profile with temporal continuity by means of remote sensing and survey in land. Some values of the key water cycle factors in the Yellow River are obtained, which include the annual precipitation of 4000 km3, the evapotranspiration of 3000-3500 km3, and the soil moisture transformation of ?500- 500 km3. Consequently, we analyzed the process of the water cycle in the Yellow River over the 1. years, and the results show that the segment upstream of Lanzhou city is a relatively humid region, and the area of internal waters and the reaches of Shanshan is the most desiccated region. Therefore, the runoff in the depth process is intensive and the runoff-generating process is weak in more arid regions.

关键词： the Yellow River, soil moisture, remote sensing, hydrologic cycle.