检索结果-南通市图书馆

Influence of pouring methods on filling process,microstructure and mechanical properties of AZ91 Mg alloy pipe by horizontal centrifugal casting

在线全文

学校读者我要写书评

暂无评论

China Foundry 2018年第3期15卷 196-202页

作者： Xue-feng Zhu Bao-yi Yu Li Zheng Bo-ning Yu Qiang Li Shu-ning Lü Hao Zhang School of Materials Science and Engineering Shenyang University of Technology

Pouring position as the input heat source has great infl uence on the temperature fi eld evolution. In this study, the Flow3 D simulation software was applied to investigate the infl uence of pouring methods(with fi xed or moving pouring channel) on AZ91 Mg alloy horizontal centrifugal casting(HCC) process. The simulation results show that the moving pouring channel method can effectively increase the cooling rate and formability of casting pipe. The casting experiment shows that an AZ91 Mg alloy casting pipe with homogeneous microstructure and clear contour was obtained by the moving pouring channel method, and the grain size of the casting pipe is signifi cantly decreased. Meanwhile, serious macro-segregation appeared in the AZ91 casting pipe by the fi xed pouring channel HCC process. Compared with the fi xed pouring channel, the moving pouring channel can remarkably improve the ultimate tensile strength and elongation of the AZ91 HCC pipe from 142.2 MPa to 201.5 MPa and 6.2% to 6.7%, respectively.

关键词： horizontal centrifugal casting (HCC) numerical simulation pouring method AZ91Mg alloy

Mechanism of production increasing of coalbed gas for the pinnate horizontal well and sensitivity effect of parameters on gas production

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2005年第S1期50卷 163-170页

作者： ZHANG Dongli & WANG Xinhai Sinopec Exploration & Production Research Institute, Beijing 100083, China College of Geoscience of Yangtze University, Jingzhou 434023, China Sinopec Exploration & Production Research Institute Beijing China College of Geoscience of Yangtze University Jingzhou China

The mechanism of production increasing for the pinnate horizontal well is analyzed with the simulation technique. It is pointed out that the whole horizontal well-bore spreading widely and evenly in coal layers makes the stratum pressure drop evenly and fast, which increases the chance of desorption and diffusion and area controlled. This is the basic reason that the pinnate horizontal well can increase production. How such stratum parameters as permeability, Langmuir constants and adsorption time constant affect the gas production for the pinnate horizontal well is also studied with numerical simulations. Either for the vertical well or the pinnate horizontal well, bigger stratum permeability, steeper relative permeability curve, smaller residual gas saturation, higher gas content and stratum pressure are more favorable for gas production increasing. Langmuir constants decide the change of desorption quantity and influence the gas production through changing the extent of steep of isothermal adsorption curves in the pressure dropping area. The adsorption time constant only influences the time that gas production arrives at the maximum value for the vertical well, but it almost has no influence on the gas production for the pinnate horizontal well because the equivalent adsorption time constant is reduced.

关键词： coalbed gas pinnate horizontal well mechanism numerical simulation sensitivity effect.

Aerosol transportation in horizontal channels w让h gravitational effects

在线全文

学校读者我要写书评

暂无评论

Particuology 2019年第3期17卷 159-168页

作者： Yongwei Gao Ke Zhong Yanming Kang School of Environmental Science and Engineering Donghua University Shanghai 201620 China School of Physics and Electronic-Electrical Engineering Ningxia University Yinchuan 750021 China

Aerosol particle deposition in a narrow horizontal channel with gravitational effects is studied in the laminar flow regime. A general explic让 solution for predicting the aerosol transportation in the channel is obtained theoretically. The characteristics of the asymmetric concentratio n profiles and their dependence on gravitational settling are analyzed for different settings of the diffusion and sedimentation parameters. Aerosol deposition on the channel walls, which is influenced by a combination of mechanisms, is also analyzed. The results are compared with those from simplified models obtained in previous studies in which only diffusion or gravity was considered. The analysis reveals that the literature results regarding this aspect may be simplified with the present solution under specific conditions.

关键词： Exact solution Combined deposition Gravitational effect horizontal channel Asymmetric distribution

Experimental study on combined buoyant-thermocapillary flow along with rising liquid film on the surface of a horizontal metallic mesh tube

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers in Energy 2020年第1期14卷 114-126页

作者： Manuel J.GOMES Ning MEI Marine Engineering Section College of EngineeringOcean University of ChinaQingdao266100China

Temperature distribution and variation with time has been considered in the analysis of the influences of the initial level of immersion of a horizontal metallic mesh tube in the liquid on combined buoyant and thermocapillary *** combined flow occurs along with the rising liquid film flow on the surface of a horizontal metallic mesh *** different levels of immersion of the metallic mesh tube in the liquid have been *** of 60 min in duration have been performed using a heating metallic tube with a diameter of 25 mm and a length of 110 mm,sealed outside with a metallic mesh of 178 mm by 178 mm,and distilled *** reveal two distinct flow *** and infrared thermal imager are utilized to measure the *** level of the liquid free surface relative to the lower edge of the tube is measured as angleθ.The results show that for a smallerθangle,or a low level of immersion,with a relatively low heating power,it is possible to near fully combine the upwards buoyant flow with the rising liquid film *** this case,the liquid is heated only in the vicinity of the tube,while the liquid away from the flow region experiences small changes in temperature and the system approaches steady *** largerθangles,or higher levels of immersion,a different flow pattern is noticed on the liquid free surface and identified as the thermo-capillary(Marangoni)*** rising liquid film is also *** higher levels of immersion cause a high temperature gradient in the liquid free surface region and promote thermal stratification;therefore the system could not approach steady conditions.

关键词： rising liquid film combined flow thermocapillary flow buoyant flow metallic mesh tube horizontal tube

horizontal gene transfer of plant-specific leucine-rich repeats between plants and bacteria

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Natural Science 2013年第5期5卷 580-598页

作者： Hiroki Miyashita Yoshio Kuroki Robert H. Kretsinger Norio Matsushima Department of Biology University of Virginia Charlottesville USA Sapporo Medical University Center for Medical Education Sapporo Japan Sapporo Medical University School of Medicine Sapporo Japan

Leucine rich repeats (LRRs) are present in over 14,000 proteins that have been identified in viruses, bacteria, archaea, and eukaryotes. Two to sixty-two LRRs occur in tandem forming an overall arc shaped domain. There are eight classes of LRRs. Plant specific LRRs (class: PS-LRR) had previously been recognized in only plant proteins. However, we find that PS-LRRs are also present in proteins from bacteria. We investigated the origin of bacterial PS-LRR domains. PSLRR proteins are widely distributed in most plants;they are found in only a few bacterial species. There are no PS-LRR proteins from archaea. Bacterial PS-LRRs in twenty proteins from eleven bacterial species (in the three phyla: Proteobacteria, Cyanobacteria, and Bacteroidetes) are significantly more similar to the PS-LRR class than to the other seven classes of LRR proteins. Not only amino acid sequences but also nucleotide sequences of the bacterial PS-LRR domains show highly significant similarity with those of many plant proteins. The program, EGID (Ensemble algorithm for Genomic Island Detection), predicts that Synechococcus sp. CYA_ 1022 came from another organism. Four bacterial PS-LRR proteins contain AhpC-TSA, IgA peptidase M64, the immunoglobulin domain, the Calx-b domain, and the He_PIG domain;these domains show no similarity with any eukaryotic (plant) proteins, in contrast to the similarities of their respective PS-LRRs. The present results indicate that horizontal gene transfer (HGT) of genes/gene fragments encoding PS-LRR domains occurred between bacteria and plants, and HGT among the eleven bacterial species, of the three phyla, as opposed to descent from a common ancestor. There is the possibility of the occurrence of one HGT event from plant to bacteria. A series of HGTs might then have occurred recently and rapidly among these eleven species of bacteria.

关键词： Leucine-Rich Repeat Plant-Specific LRR horizontal Gene Transfer Bacteria

horizontal Fire Spread in a Contemporary Apartment Based on a Real Fire

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Civil Engineering 2019年第4期9卷 367-385页

作者： Stefanie Schubert-Polzin Alexander Saupe Ulrich Krause Hochschule Magdeburg-Stendal Department of Water Environment Construction and Safety BreitscheidstraBe 2 Magdeburg Germany Institute of Apparatus and Environmental Engineering Faculty of Process and Systems Engineering Otto-von-Guericke-Universität Magdeburg Universitätsplatz 2 Magdeburg Germany

The apartment fire tests comprise a set of two full-scale fire experiments in a dwelling building made from pre-fabricated concrete elements in April 2013. Two apartments were nearly identically furnished and fully instrumented with thermocouples, video cameras and gas extraction probes. The apartments were ignited successively whereupon the fire in the second apartment developed freely to post-flashover conditions and got the main focus in this report. The apartment was completely furnished with contemporary furniture and objects, and had an average fire load density for residential occupancy. A full description of the fire load, ventilation conditions and instrumentation are provided. The focus of this report is primarily to obtain conclusions on the horizontal spread of smoke throughout the apartment during the fire growth period. Velocities of smoke spreading were measured to be in the range below 0.05 m/s which means that the smoke migrated over the longest distance throughout the apartment for about 3 to 4 minutes while the flame did not leave the initial fire room. The main aim of the experiments was to collect a comprehensive set of data from a realistic and contemporary fire scenario to validate numerical simulations.

关键词： Apartment Fire horizontal Fire Spread Smoke Spreading Full-Scale Fire Test

Ecosystem Service Flow Insights into horizontal Ecological Compensation Standards for Water Resource: A Case Study in Dongjiang Lake Basin, China

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Geographical Science 2019年第2期29卷 214-230页

作者： XU Jie XIAO Yu XIE Gaodi JIANG Yuan Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences College of Resources and Environment University of the Chinese Academy of Sciences Faculty of Geographical Science Beijing Normal University

Water supply services(WSSs) are critical for the regional water balance and water circulation, but relevant studies have not established the relationship between WSSs and human well-being. This research identifies the scope of areas that benefit from WSSs from an ecosystem service flow perspective. Moreover, the path and quantity of the flow of WSSs are simulated to provide a scientific theoretical basis for ecosystem service management and ecological compensation. The Dongjiang Lake Basin is a national priority river basin in China where ecological compensation pilot programmes concerning water resources are top priorities. Dongjiang Lake Basin experienced an increase and then a decrease in the overall supply of water, with an average net water supply of 1096–1500 mm for the years 1995, 2000, 2005 and 2010. The water demand increased each year in service beneficiary areas(SBAs), varying from 387 to 580 mm. Overall, Dongjiang Lake Basin met the net water demands of the actual SBAs in the lower reaches, but a gap in the water supply and demand emerged gradually. This research provides an understanding of the functional mechanisms for the provision, demand and flow of WSSs and provides a scientific theoretical basis for ecosystem service management and ecological compensation.

关键词： ecosystem service flow water supply services Dongjiang Lake Basin spatiotemporal patterns horizontal ecological compensation

horizontal Well Technology Utilized in China's Onshore Oilfields

在线全文

学校读者我要写书评

暂无评论

China Oil & Gas 1998年第1期5卷 19-21页

作者： Liu Xiange Jiang Zhixiang and Liu Shangqi(Research Institute of Petroleum Exploration & Development )

Preliminary Study on the horizontal Crustal Deformation in Chinese Continent

在线全文

学校读者我要写书评

暂无评论

Earthquake Research in China 2000年第4期14卷 21-31页

作者： Guo LiangqianFirst Crustal Deformation Monitoring Center, CSB, Tianjin 300180. China First Crustal Deformation Monitoring Center CSB Tianjin 300180 China

In the paper, the current strain field and stress field in Chinese continent have been discussedbased on the processed data from two GPS campaigns of national GPS network carried out inthe years of 1994 and 1996. With a principal compressional strain direction of NNE, thewestern and castern parts of Qinghai-Xizang subplate are dominated by extensional straiu andthe central Part by compressional strain. Along the southwestern segment of southeastern partof Qinghai-Xizang subplate, i. e. Yunnan area, the princiPal compressional strain direction isNW and the compressional strain is equivalent to the extensional strain in magnitude. Theprincipal compressional strain of Xinjiang subplate is mainly NNE and NE with a difference inthe strain magnitude. The principal compressional strain in North China subplate is quite effective in NE and nearly EW directions with differences along some segments. However, thecompressional strain is corresponding to the extensional strain in magnitude in most areas.

关键词： horizontal deformation GPS Crustal strain field