检索结果-南通市图书馆

Experimental Study of the Flow in Helical Circular Pipes:Torsion Effect on the Flow Velocity and Turbulence

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2008年第3期17卷 193-198页

作者： Yasutaka HAYAMIZU Kyoji yamamoto ShinichiroYANASE Toru HYAKUTAKE Toru SHINOHARA Shinichi MORITA Department of Mechanical Engineering Yonago National College of Technology Graduate School of Natural Science and Technology Okayama University

An objective of the present paper is to experimentally clarify the torsion effect on the flow in helical circular pipes. We have made six helical circular pipes having different pitches and common non-dimensional curvature δ of about 0.1. The torsion parameter β0, which is defined by β0 = τ/（2δ）1/2 with non-dimensional torsion r, are taken to be 0.02, 0.45, 0.69, 1.01, 1.38 and 1.89 covering from small to very large pitch. The velocity distributions and the turbulence of the flow are measured using an X-type hot-wire anemometer in the range of the Reynolds number from 200 to 20000. The results obtained are summarized as follows： The mean secondary flow pattern in a cross section of the pipe changes from an ordinary twin-vortex type as is seen in a curved pipe without torsion （toroidal pipe） to a single vortex type after one of the twin-vortex gradually disappears as β0 increases. The circulation direction of the single vortex is the same as the direction of torsion of the pipe. The mean velocity distribution of the axial flow is similar to that of the toroidal pipe at small β0, but changes its shape as β0 increases, and attains the shape similar to that in a straight circular pipe when ,β0 = 1.89. It is also found that the critical Reynolds number, at which the flow shows a marginal behavior to turbulence, decreases as ,β0 increases for small ,β0, and then increases after taking a minimum at ,β0 ≈ 1.4 as ,β0 increases. The minimum of the critical Reynolds number experimentally obtained is about 400 at ,β0 ≈ 1.4.

关键词： Helical Circular Pipe Torsion Effect Critical Reynolds Number Turbulence

Pulsed Laser Deposition of VO_(2)Single Crystal Thin Films on Sapphire Substrates

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1998年第12期15卷 904-906页

作者： ZHU Pei-ran S.yamamoto A.Miyashita H.Naramoto Institute of Physics Chinese Academy of SciencesBeijing 100080 Department of Materials Development Japan Atom Energy Research InstituteWatanuki 1233TakasakiGumma 370-12Japan

Thin films of VO_(2)single-crystalline on(0001)sapphire substrates have been prepared by visible pulsed laser ablation *** crystal quality and properties of the films are evaluated through electrical resistance measurement,x-ray diffraction(XRD),and Rutherford-backscattering spectroscopy/channeling(RBS/C)*** dependence of the surface electrical resistance of the films on the temperature shows semiconductor-to-metal transitions with the resistance change of 7×10^(3)-2×10^(4).The hysteresis widths are from less than 1 to 3 *** and RBS/C data reveal that the films prepared in particular conditions are single-crystalline VO_(2)with the(010)planes parallel to the surface of the sapphire substrate.

关键词： technique. sapphire Crystal

Dry Machining Tool Design via Chlorine Ion Implantation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

材料热处理学报 2004年第05B期25卷 879-882页

作者： Tatsuhiko Aizawa Atsushi Mitsuo Shigeo yamamoto Shinji Muraishi Taro Sumitomo Center for Collaborate Research University of Tokyo Tokyo JapanTokyo Metropolitan Industrial Research Institute Tokyo JapanTokyo Metropolitan Industrial Research Institute Tokyo JapanDepartment of Materials Science Technology Tokyo Institute of Technology Tokyo JapanCenter for Collaborate Research University of Tokyo Tokyo Japan

Dry machining has become a key issue to significantly reduce the wastes of used lubricants and cleaning agents and to improve the environmental consciousness for medical and food applications of special tooling. Since the tools and metallic works are in direct contact in dry, severe adhesive wear and oxidation are thought to occur even at the presence of hard protective coatings. Self-lubrication mechanism with use of lubricous oxide films is found to be effective for dry machining. Through the chlorine ion implantation to tools, titanium base oxides are in-situ formed on the tool surface. This oxide deforms elasto-plastically so that both friction coefficient and wear volume are reduced even in the high-speed cutting.

关键词：氯离子注入自动润滑 TiN涂层 TiCN涂层干机械加工

Unique Continuation Property with Partial Information for Two-Dimensional Anisotropic Elasticity Systems

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2020年第1期36卷 3-17页

作者： Jin CHENG Yi-kan LIU Yan-bo WANG Masahiro yamamoto School of Mathematical Sciences Fudan UniversityShanghai 200433China School of Mathematics Shanghai University of Finance and EconomicsShanghai 200433China Research Institute for Electronic Science Hokkaido UniversitySapporo 060-0812Japan Graduate School of Mathematical Sciences The University of TokyoTokyo 153-8914Japan Academy of Romanian Scientists 54 Splaiul Independentei StreetBucharest 050094Romania Peoples’Friendship University of Russia(RUDN University Moscow 117198Russia

In this paper,we establish a novel unique continuation property for two-dimensional anisotropic elasticity systems with partial *** precisely,given a homogeneous elasticity system in a connected open bounded domain,we investigate the unique continuation by assuming only the vanishing of one component of the solution in a *** the corresponding Riemann function,we prove that the solution vanishes in the whole domain provided that the other component vanishes at one point up to its second ***,we construct several examples showing the possibility of further reducing the additional information of the other *** result possesses remarkable significance in both theoretical and practical aspects because the required data are almost halved for the unique determination of the whole solution.

关键词： anisotropic elasticity system unique continuation,Riemann function

Saturated hydraulic conductivity of compacted bentonite-sand mixtures before and after gas migration in artificial seawater

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2023年第1期15卷 216-226页

作者： Yasutaka Watanabe Shingo Yokoyama Misato Shimbashi Yoichi yamamoto Takahiro Goto Sustainable System Research Laboratory Central Research Institute of Electric Power IndustryChibaJapan Science and Technology Department Nuclear Waste Management Organization of JapanTokyoJapan

To understand the self-healing property of an engineered barrier for radioactive waste disposal,the hydraulic conductivity of compacted bentoniteesand mixtures saturated with artificial seawater(SW)before and after gas migration was ***-and Ca-bentonites were mixed with fine sand at a ratio of 70%bentonite in dry *** aspects were considered during the experiment:the hydraulic conductivity of the specimen that was resaturated after gas migration and the distribution of water content immediately after gas migration to study gas migration *** gas migrated through the entire cross-section of the specimen,and gas breakthrough occurred in the equilibrium swelling pressure range ***,the gas flow rate reached a sufficient large value when the gas pressure was approximately twice the equilibrium axial pressure(the sum of swelling and confining pressures),which excluded the back *** the gas migration pathway was not visible when the specimen was observed immediately after gas migration,the water content distribution showed that several parts of the specimen with lower water content were connected in the direction of gas *** resaturation,the change in permeability was within a limited rangedtwo to three times larger than that before gas migration for each type of bentonite in *** slight change suggests that gas migration creates a pore structure that cannot be sealed via crystalline swelling of montmorillonite in SW,even if highly compacted bentonite is used under a constant-volume condition.

关键词： Bentonite Gas migration Hydraulic conductivity Seawater(SW) Self-healing

Sinistral portal hypertension and distal splenorenal shunt during pancreatic surgery

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2022年第1期21卷 73-75页

作者： Tomohide Hori Ryuhei Aoyama Hidekazu yamamoto Hideki Harada Michihiro yamamoto Masahiro Yamada Takefumi Yazawa Masazumi Zaima Department of Surgery Shiga General Hospital5-4-30 MoriyamaMoriyama CityShiga Prefecture524-8524Japan

Locally advanced pancreatic cancer located in the head or un-cinate process(i.e.,uncus)often invades the confluence of the superior mesenteric vein(SMV),portal vein(PV),and splenic vein(SV)[1,2].Additionally,chronic pancreatitis easily occludes drainage flow via the SV[3].These pancreatic diseases force sur-geons to perform en bloc resection of the *** ligation of the remnant SV without venous resection results in sinistral por-tal hypertension(PH)(i.e.,left-sided PH),gastrointestinal bleeding,splenic congestion,and hypersplenism over the long term[1,2].

关键词： hypertension shunt diseases

Control of oxidative stress in hepatocellular carcinoma: Helpful or harmful?

在线全文

学校读者我要写书评

暂无评论

World Journal of Hepatology 2015年第7期7卷 968-979页

作者： Akinobu Takaki Kazuhide yamamoto Department of Gastroenterology and Hepatology Okayama University Graduate School of Medicine Dentistry and Pharmaceutical Sciences

Oxidative stress is becoming recognized as a key factor in the progression of chronic liver disease(CLD) and hepatocarcinogenesis. The metabolically important liver is a major reservoir of mitochondria that serve as sources of reactive oxygen species, which are apparently responsible for the initiation of necroinflammation. As a result, CLD could be a major inducer of oxidative stress. Chronic hepatitis C is a powerful generator of oxidative stress, causing a high rate of hepatocarcinogenesis among patients with cirrhosis. Non-alcoholic steatohepatitis is also associated with oxidative stress although its hepatocarcinogenic potential is lower than that of chronic hepatitis C. Analyses of serum markers and histological findings have shown that hepatocellular carcinoma correlates with oxidative stress and experimental data indicate that oxidative stress increases the likelihood of developing hepatocarcinogenesis. However, the results of antioxidant therapy have not been favorable. Physiological oxidative stress is a necessary biological response, and thus adequate control of oxidative stress and a balance between oxidative and anti-oxidative responses is important. Several agents including metformin and L-carnitine can reportedly control mechanistic oxidative stress. This study reviews the importance of oxidative stress in hepatocarcinogenesis and of control strategies for the optimal survival of patients with CLD and hepatocellular carcinoma.

关键词： Liver cancer Liver cirrhosis Hepatitis B Viral protein C Non-alcoholic steatohepatitis Reactiveoxygen species

Galling phenomena in metal forming

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2021年第4期9卷 665-685页

作者： Kuniaki DOHDA Masahito yamamoto Chengliang HU Laurent DUBAR Kornel F.EHMANN Department of Mechanical Engineering Northwestern UniversityEvanstonIL 60208-3111USA Manufacturing Engineering Center NSKLtd.Fujisawa-Shi 251-8501Japan Institute of Forming Technology and Equipment School of Materials and EngineeringShanghai Jiao Tong UniversityShanghai 200240China LAMIH UMR CNRS 8201 Universite Polytechnique Hauts-de-FranceValenciennes Cedex 959313France

Galling phenomena in metal forming not only affect the quality of the engineered surfaces but also the success or failure of the manufacturing operation *** paper reviews the different galling conditions in sheet and bulk metal forming processes along with their evolution and the effects of temperature on galling.A group of anti-galling methods employed to prevent galling defects are also presented in *** techniques for quantitatively measuring galling are introduced,and the related prediction models,including friction,wear,and galling growth models,are presented to better understand the underlying *** phenomena in other processes similar to those occurring in metal forming are also examined to suggest different ways of further studying galling in metal ***,future research directions for the study of galling in metal forming are suggested.

关键词： galling metal forming friction wear adhesion anti-galling

New Reflection Principles for Maxwell's Equations and Their Applications

在线全文

学校读者我要写书评

暂无评论

Numerical Mathematics(Theory,Methods and Applications) 2009年第1期2卷 1-17页

作者： Hongyu Liu Masahiro yamamoto Jun Zou Department of Mathematics University of Washington Box 354350 Seattle WA 98195 USA. Department of Mathematical Sciences The University of Tokyo Komaba Meguro Tokyo 153-8914 Japan. Department of Mathematics The Chinese University ofHong Kong Shatin N.T. Hong Kong.

Some new reflection principles for Maxwell's equations are first established, which are then applied to derive two novel identifiability results in inverse electromagnetic obstacle scattering problems with polyhedral ... 详细信息

关键词： Maxwell's equations reflection principles inverse electromagnetic scattering identiflability and uniqueness.