检索结果-南通市图书馆

Hydraulic characteristics of converse curvature section and aerator in high-head and large discharge spillway tunnel

在线全文

学校读者我要写书评

暂无评论

Science china(Technological sciences) 2011年第S1期54卷 33-39页

作者： LIU ZhiPing 1,2,ZHANG Dong 2,ZHANG HongWei 2 &wu YiHong 1,2 1 state key {3. of Simulation and Regulation of Water Cycle in River Basin,beijing 10003.,china 2 china institute of Water Resources and Hydropower Research,beijing 10003.,china 1. state key laboratory of Simulation and Regulation of Water Cycle in River Basin Beijing 100038 China2. China Institute of Water Resources and Hydropower Research Beijing 100038 China

The hydraulic characteristics and cavitation erosion near the converse curvature section in the high-head and large discharge spillway tunnel have been important issues of concern to the hydropower *** this paper,the evolutions of hydraulic elements such as pressure,flow velocity,wall shear stress,*** the converse curvature section are analyzed and the impacts of bottom aerator on hydraulic characteristics are discussed,with the commercial software FLUENT6.3.as a platform and combining the k-model and VOF *** flow pattern in the converse curvature section of spillway tunnel is given by the three-dimensional numerical *** indicates that the pressure changes rapidly with great pressure gradient from the beginning to the end of the *** also shows that the shear stress on side wall just downstream the end of the converse curvature curve is still increasing;the aeration cavity formed downstream the bottom aerator may cause the side wall pressure decreased to worsen the cavitation characteristics near the side *** means of the physical model experiment,the three-dimensional aerator composed of side wall baffling aerator and bottom aerator is studied,the baffling aerator suitable for the water flow conditions with water depth of 6.0 to 8.0 m and flow velocity of 3. to 50 m/s is proposed.

关键词： spillway tunnel baffling aerator converse curvature section hydraulic characteristics

Holographic Storage Parametric Optimization of the Crystal LiNbO3.Fe Based on One-center Model

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Lasers 2002年第1期11卷 28-34页

作者： WANG Jiangang HE Qingsheng JIN Guofan wu Minxian (state key {3. of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, beijing 100084, china) Department of Precision Instruments Tsinghua University State Key Laboratory of Precision Measurement Technology and Instruments 北京 100084

Based on one-center model, the effects of the doping amount and the degrees of reduction and oxidation on the dynamic range M, the response time and the photorefractive sensitivity in the crystal LiNbO 3.Fe are analyzed in detail. The principle of material optimization is discussed. The best crystal thickness (about 1.4～2.6 mm) for the maximum dynamic range M is calculated for the different doping amounts. The results show that the more the doping amount, the lighter the reduction of the crystal should be chosen, and that the heavier the reduction of the crystal, the less effect the doping amount has on the response time. The dynamic range M is in conflict with the response time. Due to the difficulty of processing crystals, the thickness is increased to 5 mm at the cost of decreasing the dynamic range M by 0.3.0.5.

关键词： holographic storage materials parametric optimization LiNbO 3.Fe crystals

Effect of welding speed on the material flow patterns in friction stir welding of AZ3. magnesium alloy

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2007年第2期26卷 158-162页

作者： ZHANG Hua wu Huiqiang Huang Jihua LIN Sanbao wu Lin Materials Science and Engineering School University of Science and Technology Beijing Beijing 100083 China beijing institute of Astronautical Systems Engineering Beijing 100076 China state key Lab of Advanced Welding Production Technology Harbin Institute of Technology Harbin 150001 China

The clear zigzag-line pattern on transverse cross sections can be used to explain the formation mechanism of the weld nugget when friction stir welded AZ3. magnesium alloy without any other insert material is used as mark. It provides a simple and useful method to research the joining mechanism of friction stir welding. The rotation speed is kept at 1000 r/min and the welding speed changes from 120 mm/min to 600 mm/min. The macrostructure on the transverse cross section was divided into several parts by faying surface. The results show that the shape and formation procedure of the weld nugget change with the welding speed. There are two main material flows in the weld nugget： one is from the advancing side and the other is from the retreating side. A simple model on the weld nugget formation of FSW is presented in this article.

关键词： AZ3. magnesium alloy friction stir welding faying surface materials flow formation model

Identification of QTLs for grain size and characterization of the beneficial alleles of grain size genes in large grain rice variety BL129

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2016年第1期15卷 1-9页

作者： GAO Xua ZHU Xu-dong FANG Na DUAN Peng-gen wu Ying-bao LUO Yue-hua LI Yun-hai Hainan key laboratory for Sustainable Utilization of Tropical Bioresources/Agricultural College Hainan UniversityHaikou 570228P.R.China state key laboratory of Rice Biology China National Rice Research InstituteChinese Academy of Agricultural SciencesHangzhou 310006P.R.China state key laboratory of Plant Cell and Chromosome Engineering Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing 100101P.R.China

Grain size is one of the most important agronomic components of grain yield. Grain length, width and thickness are controlled by multiple quantitative trait loci （QTLs）. To understand genetic basis of large grain shape and explore the beneficial alleles for grain size improvement, we perform QTL analysis using an F2 population derived from a cross between the japonica variety Beilu 129 （BL129, wide and thick grain） and the elite indica variety Huazhan （HZ, narrow and long grain）. A total number of eight major QTLs are detected on three different chromosomes. QTLs for grain width （qGW）, grain thickness （qGT）, brown grain width （qBGW）, and brown grain thickness （qBGT） explained 77.67, 3..24, 89.63. and 3..41% of total phenotypic variation, respectively. The large grain rice variety BL129 possesses the beneficial alleles of GW2 and qSW5/ GW5, which have been known to control grain width and weight, indicating that the accumulation of the beneficial alleles causes large grain shape in BL129. Further results reveal that the rare gw2 allele from BL129 increases grain width, thickness and weight of the elite indica variety Huazhan, which is used as a parental line in hybrid rice breeding. Thus, our findings will help breeders to carry out molecular design breeding on rice grain size and shape.

关键词： rice quantitative trait grain size GW2 GW5

Generation of fad2 transgenic mice that produce omega-6 fatty acids

在线全文

学校读者我要写书评

暂无评论

Science china(Life sciences) 2009年第11期52卷 1048-1054页

作者： CHEN Qing1, LIU Qing2, wu ZhiFang1, WANG ZongYi3.& GOU KeMian1 1 state key {3. for Agrobiotechnology, china Agricultural University, beijing 100193. china 2 Blackmountain {3., CSIRO Plant Industry, Canberra, Australia 3.College of Animal Science and Technology, china Agricultural University, beijing 100193. china 1. state key laboratory for Agrobiotechnology China Agricultural University Beijing 100193 China 2. Blackmountain laboratory CSIRO Plant Industry Canberra Australia 3. College of Animal Science and Technology China Agricultural University Beijing 100193 China

Fatty acid desaturase-2 (FAD2) introduces a double bond in position 12 in oleic acid (18:1) to form linoleic acid (18:2 n-6) in higher plants and microbes. A new transgenic expression cassette, containing CMV promoter/fad2 cDNA/SV40 polyA, was constructedto produce transgenic mice. Among 63.healthy offspring, 10 founders (15.9%) integrated the cotton fad2 transgene into their genomes, as demonstrated by PCR and Southern blotting analysis. All founder mice were fertile and heterozygous fad2 female and nontransgenic littermates were used for fatty acid analysis using gas chromatography. One fad2 transgenic line showed substantial differences in the fatty acid profiles and the level of linoleic acid was increased 19% (P<0.05) in transgenic muscles compared to their nontransgenic littermates. Moreover, it exhibited an 87% and a 9% increase (P<0.05) in arachidonic acid (20:4 n-6) in muscles and liver, compared to their nontransgenic littermates. The results indicate that the plant fad2 gene can be functionally expressed in transgenic mice and may playan active role in conversion of oleic acid into linoleic acid.

关键词： fatty acid desaturase FAD2 transgenic mouse oleic acid linoleic acid arachidonic acid

Cloning and Sequencing of a Gene Encoding Aminopeptidase N in the Midgut of Helicoverpa armigera(Hubner)

在线全文

学校读者我要写书评

暂无评论

Agricultural sciences in china 2003年第7期2卷 760-767页

作者： WANG Gui-rong, LIANG Ge-mei, wu Kong-ming and GUO Yu-yuan(state key {3. of Plant Disease and Insect Pests , institute of Plant Protection , chinese academy of Agricultural sciences , beijing 100094 , P.R.china) state key laboratory of Plant Disease and Insect Pests Institute of Plant Protection Chinese Academy of Agricultural Sciences Beijing 100094 P. R. China

A cDNA encoding aminopeptidase N was cloned by degenerated PCR combined with RACE technique in this paper. The full-length of APN-Harm is 3.043.bp. Open reading frame is 2 856 bp in length, encoding 951 amino acid residues. Its predicted molecular weight and isoelectric point are 108. 3.kDa and 5.29, respectively. This deduced amino acid sequence shares some common structural features with aminopeptidase N from several moth species, including the consensus zinc-binding motif HEXXHX18E and the GAMEN motif common to gluzincin aminopeptidases. The first 20 amino acid residues at N-termini is hydrophobic transmembrane helix. The sequence of APN-Harm was deposited in GenBank and the accession number is AY181026.

关键词： Helicoverpa armigera Aminopeptidase N Gene cloning

Sediment delivery ratio and its uncertainties on flood event scale:Quantification for the Lower Yellow River

在线全文

学校读者我要写书评

暂无评论

Science china(Technological sciences) 2010年第3期53卷 854-862页

作者： FU XuDong 1,JIANG LiWei 1,wu BaoSheng 1,HU ChunHong 2,WANG GuangQian 1 &FEI XiangJun 1 1state key {3. of Hydroscience and Engineering,Tsinghua University,beijing 100084,china 2china institute of Hydropower and Water Resources Research,beijing 100044,china 1. state key laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China2. China Institute of Hydropower and Water Resources Research Beijing 100044 China

Sediment delivery ratio(SDR)for fluvial rivers was formulated with sediment rating *** observed data of SDR on flood event scale of the Lower Yellow River(LYR)were adopted to examine the formulation and to calibrate the model parameters.A regression formula of SDR was then established and its 95%prediction interval was accordingly quantified to represent its overall *** types of factors including diversity of the incoming flow conditions,river self-regulation processes,and human activities were ascribed to the *** following were shown:(1)With the incoming sediment coefficient(ISC)being a variable,it was not necessary to adopt the incoming flow discharge as the second variable in the formulation of SDR;and(2)ISC=0.003.and therefore SDR=2 might be a threshold for distinguishing the characteristics of sediment transport within the *** findings would highlight sediment transport characteristics on the scale of flood event and contribute to uncertainty based analysis of water volume required for sediment transport and channel maintenance of the LYR.

关键词： sediment delivery ratio Lower Yellow River flood event uncertainty prediction interval

Cluster-based composition rule for Laves phase-related BCC solid solution hydrogen storage alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第z1期25卷 252-255页

作者： WANG Qing CHEN Feng wu Jiang QIANG Jianbing DONG Chuang ZHANG Yao XU Fen SUN Lixian state key laboratory of Materials Modification Dalian University of Technology Dalian 116024 China State Key Laboratory of Materials Modification Dalian University of Technology Dalian 116024 China State Key Laboratory of Materials Modification Dalian University of Technology Dalian 116024 China State Key Laboratory of Materials Modification Dalian University of Technology Dalian 116024 China State Key Laboratory of Materials Modification Dalian University of Technology Dalian 116024 China International Center of Materials Physics Metals Research Institute Chinese Academy of Sciences Shenyang 110015 China Materials & Thermochemistry Laboratory Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China Materials & Thermochemistry Laboratory Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China Materials & Thermochemistry Laboratory Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China

A new cluster line approach for the composition rule of Laves phase-related BCC solid solution hydrogen-storage alloys was presented. The cluster line in a ternary phase diagram refers to a straight composition line linking a specific binary cluster to the third element. In the Laves phase-related BCC solid solution alloy system such as Ti-Cr-V, Ti-Cr tends to form binary Cr2Ti Laves phase while Ti-V and Cr-V to form solid solutions. This Laves phase is characterized by a close-packing icosahedral cluster Cr7Ti6. A cluster line Cr7Ti6-V is then constructed in this system. Alloy rods with a diameter of 3.mm of compositions along this line were prepared by copper-mould suction method. The alloy structure is found to vary with the V contents. Furthermore, the P-C-T measurements indicate that the cluster-line (Cr7Ti6)1-xVx alloys have large hydrogen storage capacities.

关键词： Ti-Cr-V alloys composition rule cluster hydrogen storage

Nitrogen removal via nitrite from municipal landfill leachate

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental sciences 2009年第11期21卷 1480-1485页

作者： wu Lina, PENG Chengyao, ZHANG Shujun, PENG Yongzhen key laboratory of {3. for Water Quality Science and Water Environment Recovery Engineering, {3. University of Technology, {3. 100124, china. [a]key laboratory of beijing for Water Quality Science and Water Environment Recovery Engineering Beijing University of Technology Beijing 100124 China

A system consisting of a two-stage up-flow anaerobic sludge blanket （UASB）, an anoxic/aerobic （A/O） reactor and a sequencing batch reactor （SBR）, was used to treat landfill leachate. During operation, denitrification and methanogenesis took place simultaneously in the first stage UASB, and the effluent chemical oxygen demand （COD） was further removed in the second stage UASB. Then the denitrification of nitrite and nitrate in the returned sludge by using the residual COD was accomplished in the A/O reactor, and ammonia was removed via nitrite in it. Last but not least, the residual ammonia was removed in SBR as well as nitrite and nitrate which were produced by nitrification. The results over 120 d （60 d for phase I and 60 d for phase II） were as follows： when the total nitrogen （TN） concentration of influent leachate was about 2500 mg/L and the ammonia nitrogen concentration was about 2000 mg/L, the shortcut nitrification with 85%-90% nitrite accumulation was achieved stably in the A/O reactor. The TN and ammonia nitrogen removal efficiencies of the system were 98% and 97%, respectively. The residual ammonia, nitrite and nitrate produced during nitrification in the A/O reactor could be washed out almost completely in SBR. The TN and ammonia nitrogen concentrations of final effluent were about 3. mg/L and 12 mg/L, respectively.

关键词： short-cut nitrification up-flow anaerobic sludge blanket anoxic/aerobic reactor sequencing batch reactor landfill leachate