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Computational theory of cavitating flows for hydraulic turbomachinery with consideration of influence of water quality

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Science china(Technological Sciences) 2010年第12期53卷 3341-3348页

作者： WANG Lei1,2 & CHANG JinShi2 1 Huadian Electric Power Research Institute, Hangzhou 310030, china 2 college of Water Conservancy and Civil engineering, china agricultural university, beijing 100083. china Huadian Electric Power Research Institute Hangzhou China college of Water Conservancy and Civil engineering China Agricultural University Beijing China

Previously it was assumed that the pressure within the cavity or on the cavity surface remained constant and the vapor pressure of clean water at 20°C and 0 m altitude was utilized as the computational boundary for cavitating flows in hydraulic turbomachinery. Cavitation was confused with vaporization, and the effect of water quality on cavitation pressure characteristics was not taken into account. In recent years, lots of experiments of cavitation pressure characteristics of different water qualities including different sand concentrations of sand water and different altitudes of clean water have been performed by the authors, and the important influences of water quality on cavitation pressure characteristic have been validated. Thus the water quality should be involved in the cavitating flows computation. In the present paper, the effect of water quality on the cavitation pressure characteristic is analyzed and the computational method and theory of cavitating flows for hydraulic turbomachinery that considers the influence of water quality are proposed. The theory is suitable for both the potential flow method and the two-phase flow method for cavitating flows simulation. Finally, the validation results for cavitating flows in a hydraulic tur- bine indicate the significant influences of water quality on the cavitating flow performance.

关键词： cavitating flows cavitation pressure water quality hydraulic turbomachinery

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Prediction of human skin permeability using artificial neural network (ANN) modeling

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Acta Pharmacologica Sinica 2007年第4期28卷 591-600页

作者： Long-jian CHEN~2,Guo-ping LIAN~3,Lu-jia HAN~(2,4)~2college of engineering,china agricultural university,beijing 100083.china ~3Unilever Corporate Research,Bedford MK44 1LQ,UK college of engineering China Agricultural University Beijing China Unilever Corporate Research Bedford UK

Aim:To develop an artificial neural network （ANN） model for predicting skinpermeability （log Kp） of new chemical ***:A large dataset of 215experimental data points was compiled from the *** dataset was subdi-vided into 5 subsets and 4 of them were used to train and validate an ANN *** same 4 datasets were also used to build a multiple linear regression （MLR）*** remaining dataset was then used to test the 2 *** were employed as inputs into the 2 *** predictions werecompared with the experimental *** addition,the relationship betweenlog Kpand Abraham descriptors were ***:The regression re-sults of the MLR model were n=215,determination coefficient （R2）=0.699,meansquare error （MSE）=0.243,and F=*** ANN model gave improved resultswith n=215,R2=0.832,MSE=0.136,and F= *** ANN model suggests thatthe relationship between log Kpand Abraham descriptors is ***:The study suggests that Abraham descriptors may be used to predict skinpermeability,and the ANN model gives improved prediction of skin permeability.

关键词： ANN model diffusion permeability quantitative structure-activity relationship skin

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REMARKS ON THE BINDING NUMBER FOR [a,b]-FACTORS

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Systems Science and Mathematical Sciences 1992年第2期5卷 141-145页

作者： CHEN Ciping (beijing agricultural engineering university,beijing 100083.china) 中国农业工程大学北京

We give some answers to the following question:If the binding numberof a graph G is more than 1+(a-1)/b,does G have an [a,b] -factor?

关键词： Graph factor binding number

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Neuroglobin mutation associated with hypoxia adaptation in Tibet chicken

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Progress in Natural Science:Materials International 2007年第12期17卷 1419-1424页

作者： Zhang Lifan1, Liu Chong2, Lian Linsheng3, Zhao Chunjiang1, Bao Haigang1 and Wu Changxin1(1. college of Animal Science and Technology, china agricultural university, beijing 100094, china 2. college of Biological Science, china agricultural university, beijing 100094, china 3. college of Animal Science and Technology, Yunnan agricultural university, Kunming 650201, china) college of Animal Science and Technology China Agricultural University Beijing 100094 China college of Biological Science China Agricultural University Beijing 100094 China college of Animal Science and Technology Yunnan Agricultural University Kunming 650201 China

Globin protein family plays an important role in storing and transporting oxygen. As a newly reported globin, the revealed function of neuroglobin includes binding and storing oxygen as well as facilitating the utilization of oxygen in neuronal cells. In the present study, mutations in exons of chicken Ngb gene were identified with the method of sequencing and created restriction site PCR in Tibet chicken and other four lowland chicken breeds. The mutations of Lys-2224(E4)-Asn and Ser-2279(E4)-Gly were identified in exon 4 of the gene. The Lys-2224(E4)-Asn mutation existed only in Tibet chicken and the mutation frequencies increased with increasing altitude. Analysis of the haplotype and diplotype of the two mutations in Tibet chicken populations of different altitudes showed that the frequencies of TG haplotype and TTGG diplotype also increased with increasing altitude, while the reverse tendency was found on GGAA diplotype. Under the hypoxic simulation incubation, the main haplotype was TG in living embryos and GA in dead embryos. The results showed that the Lys-2224(E4)-Asn mutation may be a specific mutation associated with hypoxia adaptation in Tibet chicken.

关键词： Tibet chicken neuroglobin hypoxia adaptation Ngb gene mutation.

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NUMERICAL INVESTIGATION OF PERFORMANCE OF AN AXIAL-FLOW PUMP WITH INDUCER

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Journal of Hydrodynamics 2007年第6期19卷 705-711页

作者： LI Yao-jun WANG Fu-jun college of Water Conservancy and Civil engineering China Agricultural University Beijing 100083 China

The interaction of flow through the inducer and impeller of an axial-flow pump equipped with an inducer has significant effect on its performance. This article presents a recent numerical investigation on this topic. The studied pump has an inducer with 3 blades mounted on a conical hub and a 6-blade impeller. The blade angle of the impeller is adjustable to generate different relative circumferential angles between the inducer blade trailing edge and the impeller blade leading edge. A computational fluid dynamics code was used to investigate the flow characteristics and performance of the axial-flow pump. For turbulence closure, the RNG k-ε model was applied with an unstructured grid system. The rotor-stator interaction was treated with a Multiple Reference Frame （MRF） strategy. Computations were performed in different cases： 7 different relative circumferential angles （ Δθ ） between the inducer blade trailing edge and the impeller blade leading edge, and 3 different axial gaps （G） between the inducer and the impeller. The variation of the hydraulic loss in the rotator was obtained by changing Δθ . The numerical results show that the pressure generated is minimum in the case of （ G = 3%D）, which indicates that the interference between inducer and impeller is strong if the axial gap is small. The pump performances were predicted and compared to the experimental measurements. Recommendations for future modifications and improvements to the pump design were also given.

关键词： axial-flow pump inducer CFD numerical simulation of flow

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NEW ROBUST UNSUPERVISED SUPPORT VECTOR MACHINES

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Journal of Systems Science & Complexity 2011年第3期24卷 466-476页

作者： Kun ZHAO Mingyu ZHANG ~ Naiyang DENG Logistics School Beijing Wuzi University Beijing 101149 China. School of Economic and Management Beijing Jiaotong University Beijing 100044 China. college of Science China Agricultural University Bcijing 100083 China.

This paper proposes robust version to unsupervised classification algorithm based on modified robust version of primal problem of standard SVMs, which directly relaxes it with label variables to a semi-definite progra... 详细信息

关键词： Robust semi-definite programming support vector machines unsupervised learning

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Preparation and microstructure of CuO-CoO-MnO/SiO2 nanocomposite aerogels and xerogels as catalyst carriers

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Progress in Natural Science:Materials International 2011年第4期21卷 330-335页

作者： Yue-qing ZHAO~1,Ying-hua LIANG~2,Xi-zhe ZHAO~3,Qian-yi JIA~4,Hong-sheng LI~4 1.college of Light Industry,Hebei United university,Tangshan 063000,china 2.college of Chemical engineering,Hebei United university,Tangshan 063009,china 3.college of Printing and Packaging engineering,beijing Institute of Graphic Communication,beijing 102600,china 4.college of Materials Science and engineering,Hebei United university,Tangshan 063009,china college of Light Industry Hebei United University Tangshan 063000 China college of Chemical engineering Hebei United University Tangshan 063009 China college of Printing and Packaging engineering Beijing Institute of Graphic Communication Beijing 102600 China college of Materials Science and engineering Hebei United University Tangshan 063009 China

CuO-CoO-MnO/SiO2nanocomposite aerogels and xerogels were prepared using tetraethyl orthosilicate（TEOS） as Si source,and aqueous solution of Cu,Co and Mn acetates as the precursor via sol-gel process,CO2supercritical drying（SCD） technique or ambient pressure drying *** microstructure of the CuO-CoO-MnO/SiO2nanocomposite aerogels and xerogels were characterized by field emission scanning electron microscopy（FE-SEM）,transmission electron microscopy（TEM） and X-ray diffraction（XRD）.The specific surface area,pore size and pore size distribution of the nanocomposite aerogels and xerogels were determined by the Brunauer-Emmett-Teller（BET） *** results showed that CuO-CoO-MnO/SiO2nanocomposite aerogels are porous,with a pore size distribution of 2-50 nm,an average pore size of 19.4 nm,a specific surface area of 384.9 m2/g and a particle size distribution of 10-150 nm,whereas the pore size distribution of CuO-CoO-MnO/SiO2composite xerogels is 1.7-128.6 nm,the average pore size is only 9.9 nm,the specific surface area is only 99.1 m2/g,and the particle size distribution is 100-500 *** structure of CuO-CoO-MnO/SiO2nanocomposite aerogels is favorable to increase the loading of catalysts.

关键词： composite aerogel composite xerogel catalyst carrier preparation microstructure

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Mesh theory of angle modified dual tori double-enveloping toroidal worm drive

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Science china(Technological Sciences) 2010年第7期53卷 1913-1927页

作者： ZHAO YaPing1, SU DaiZhong2, ZHANG Zhao1, WEI WenJun3 & DONG XueZhu3 1 college of Machinery and Automation, Wuhan university of Science and Technology, Wuhan 430081, china 2 Advanced Design and Manufacturing engineering Center, Nottingham Trent university, Nottingham NG1 4BU, UK 3.college of engineering, china agricultural university, beijing 100083. china college of Machinery and Automation Wuhan University of Science and Technology Wuhan China Advanced Design and Manufacturing engineering Center Nottingham Trent University Nottingham UK college of engineering China Agricultural University Beijing China

In this paper, the meshing theory of the angle modified hourglass worm drive is enriched and developed. The ordinary condition of the angle modification is derived and the physical significance of the modification is interpreted. A normal section methodology is proposed for meshing analysis, which can be used to compute the normal distance near a singular meshing point of a conjugate surface couple. By means of the method and after analyzing the normal transversals, it is specified that the worm helicoid, the nominal former contact zone and the new contact zone intersect each other along the locus of singular points of the instantaneous contact lines of an angle-modified worm pair. As a result, it is explained clearly that those three osculate each other but the osculations are different in degree. Moreover, the mechanism of removing the twice-contacted zone from the worm gear tooth surface is clarified and the reason of shortening the worm working length is also elucidated. With the help of the theory described in the present paper and the thorough and systematic research on the relevant meshing characteristics, the angle modified dual tori double-enveloping toroidal worm drive has been shown to be an excellent new-fashioned hourglass worm set.

关键词： hourglass worm angle modification double-enveloping osculation normal transversal

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Single-molecule studies of DNA by molecular combing

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Progress in Natural Science:Materials International 2007年第5期17卷 493-499页

作者： Liu Yuying, Wang Pengye and Dou Shuoxing (college of Science, china agricultural university, beijing 100083. china Laboratory of Soft Matter Physics, beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, beijing 100080, china) college of Sciences China Agricultural University Beijing 100083 China Laboratory of Soft Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China

Molecular combing is a powerful method for aligning a large array of DMA molecules onto a surface. It is a process whereby DNA molecules are stretched and aligned on a glass surface by the force via fluid flow. The ability to comb up to several hundred DNAs on a single cover slip allows for a statistically significant number of measurements to be made. These features make molecular combing an attractive tool for genomic studies, such as DNA replication, DNA transcription, DNA-protein interaction and so on. In this review article, we discuss the molecular combing principle, method and its applications.

关键词： DNA molecule molecular combing DNA-protein interaction.

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Efficient visualization techniques for high resolution remotely sensed data in a network environment

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Science china(Technological Sciences) 2008年第S1期51卷 124-134页

作者： WENG JingNong1,WU Lun2,HUANG Jian1,XIA YuBin3 & CAI Heng1 1 college of Software,Beihang university,beijing 100083.china 2 Institute of Geographical Information System and Remote Sensing,Peking university,beijing 100871,china 3.college of Computer,Beihang university,beijing 100083.china college of Software Beihang University Beijing China Institute of Geographical Information System and Remote Sensing Peking University Beijing China college of Computer Beihang University Beijing China

There are three major research hotspots in efficient visualization techniques of high resolution remotely sensed data in network environment: the data organiza-tion and access in disk storage,the image data stitching and fitting methods,and the network transfers and access. In this paper a new method of "Big File" organi-zation for improving the storage access efficiency of high resolution remote data is presented; a "virtual data source" concept is introduced to solve the stitching problem of remotely sensed data from different sources with different resolutions; a remotely sensed data access engine design based on ATL technique is discussed to process the network transfers and access of remotely sensed data. All these techniques have been adopted in a prototype of digital china named "chinaStar".

关键词： high resolution remotely sensed data spatial index pyramid model LOD Big File

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