检索结果-南通市图书馆

NUMERICAL SIMULATION OF TWO-DIMENSIONAL DAM-BREAK FLOWS IN CURVED CHANNELS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第6期19卷 726-735页

作者： BAI yu-chuan xu dong LU dong-qiang Institute for Sediment on River and Coast 300072 China Shanghai Institute of Applied Mathematics Engineering School of Civil Engineering Tianjin University Tianjin and Mechanics Shanghai University Shanghai 200072 China

Two-dimensional transient dam-break flows in a river with bends were theoretically studied. The river was modeled as a curved channel with a constant width and a flat bottom. The water was assumed to be an incompressible and homogeneous fluid. A channel-fitted orthogonal curvilinear coordinate system was established and the corresponding two-dimensional shallow-water equations were derived for this system. The governing equations with well-posed initial and boundary conditions were numerically solved in a rectangular domain by use of the Godunov-type finite-difference scheme, which can capture the hydraulic jump of dam-break flows. The comparison between the obtained numerical results and the experimental data of Miller and Chaudry in a semicircle channel shows the validity of the present numerical scheme. The mathematical model and the numerical method were applied to the dam-break flows in channels with various curvatures. Based on the numerical results, the influence of river curvatures on the dam-break flows was analyzed in details.

关键词： dam-break flow shallow-water equations,channel bend curvilinear coordinate Godunov-type finite-difference scheme

Microcracks repairing technique for gun barrel

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第Z1期14卷 219-221页

作者： yu xu-dong WU Bin SU Bing WANG Cheng-tao Military Engineering Department Artillery Academy Hefei 230031 China Military Engineering Department Artillery Academy Hefei 230031 China School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030China School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030China

When a gun fires the diffusion of chemical species from the propellant gas, such as CO, CO2, H2, H2O and N2, into the hot surface through the microcracks forms reaction products and speeds up the erosion ***, crack repairing and healing can be a possible measure for protecting against erosion of gun bore. The present study develops a novel nanocomposite with the size of 30 - 150 nm to repair and heal the microcracks so that the propellant gas can be prevented from reacting with the steel. Sample of gun steel 40CrNiMoV plate (10 mm× 10 mm × 2 mm) is prepared and a fishtail crack is generated through a repeated plastic deformation process. The crackrepairing results show that the fishtail crack become shorter and narrower. A new phase is formed, which is found to have the elements, such as Ca, La, from the raw materials of nanocomposite by energy spectrum analysis.

关键词： nanocomposite microcrack repair

Surface and interface analysis of HAP/TiO2 composite films on Ti6Al4V

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第Z1期14卷 193-198页

作者： SU Bing ZHANG Weng-guang yu xu-dong WANG Cheng-tao School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200030 China School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200030 China 1st Department Artillery Academy of PLA of China Hefei 230031 China School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200030 China

The composite films constituted of hydroxyapatite (HAP) submicron particles embedded in the gel composed of the titania nanoparticles were prepared on commercial Ti6Al4V plates with titania buffer layer obtained by a spin-coating technique. The films were annealed in air at 450 ℃, 550 ℃ and 650 ℃, respectively. The phase formation, surface morphology, andinterfacial microstructure of the films were investigated by X-ray diffraction(XRD),Fourier transform infrared spectroscopy (FT-IR), field emission-scanning electron microscopy(FE-SEM) and energy dispersive X-ray (EDS) analysis. The results show that the as-prepared films are all well-crystallized, dense,homogeneous, and there was a close interfacial bond between the film and the substrate. The results of adhesion test indicate that there is a good bonding strength between the film and the substrate. The bone-like apatite formation on the surface of the films after immersion in acellular simulatedbody fluid(SBF) validated their bioactivities.

关键词： titanium dioxide hydroxyapatite composite film spin-coating technique

Inhibitory Effect of S100A11 on Airway Smooth Muscle Contraction and Airway Hyperresponsiveness

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Current Medical Science 2022年第2期42卷 333-340页

作者： Mi CHENG Yang-lin SHI Pan-pan SHANG Yan-jiao CHEN yu-dong xu Shanghai Research Institute of Acupuncture and Meridian Yueyang Hospital of Integrated Traditional Chinese and Western MedicineShanghai University of Traditional Chinese MedicineShanghai200030China

Objective S100A11 is a member of the S100 calcium-binding protein family and has intracellular and extracellular regulatory *** previously reported that S100A11 was differentially expressed in the respiratory tracts of asthmatic rats as compared with normal ***,we aimed to analyze the potential of S100A11 to regulate both allergen-induced airway hyperresponsiveness(AHR)as well as acetylcholine(ACh)-induced hypercontractility of airway smooth muscle(ASM)and contraction of ASM cells(ASMCs).Methods Purified recombinant rat S100A11 protein(rS100A11)was administered to OVA-sensitized and challenged rats and then the AHR of animals was *** relaxation effects of rS100A11 on ASM were detected using isolated tracheal rings and primary *** expression levels of un-phosphorylated myosin light chain(MLC)and phosphorylated MLC in ASMCs were analyzed using Western *** Treatment with rS100A11 attenuated AHR in the *** contraction assays showed that rS100A11 reduced the contractile responses of isolated tracheal rings and primary ASMCs treated with *** addition,rS100A11 markedly decreased the ACh-induced phosphorylation of the myosin light chain in ***,rS100A11 also suppressed the contractile response of tracheal rings in calcium-free buffer *** These results indicate that S100A11 protein can relieve AHR by relaxing ASM independently of extracellular *** data support the idea that S100A11 is a potential therapeutic target for reducing airway resistance in asthma patients.

关键词： S100A11 asthma airway hyperresponsiveness airway smooth muscle relaxation

THE EFFECT OF OIL CAVITY DEPTH ON TEMPERATURE FIELD IN HEAVY HYDROSTATIC THRUST BEARING

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2011年第5期23卷 676-680页

作者： SHAO Jun-peng DAI Chun-xi ZHANG Yan-qin yu Xiao-dong xu Xiao-qiu WANG yun-fei College of Mechanical and Power Engineering Harbin UniverSity of Science and Technology Harbin150080 China

For a heavy hydrostatic bearing with a high linear velocity, the results of numerical calculations often differ from practical conditions if the viscosity is considered as constant. In this article, the influence of the oil cavity depth on the temperature field in the heavy hydrostatic bearing is discussed in the context of variable viscosity. The viscosity-temperature relations for the gap oil film are first established by fitting B-Spline curves, then, numerical calculations for the temperature field in the heavy hydrostatic bearing of different oil cavity depths are carried out based on Finite Volume Method （FVM） under the same rotating speed, and the influence of the oil cavity depth on the temperature distribution in the gap oil film of the hydrostatic bearing is discussed. The results of numerical calculations provide the temperature distribution state inside the hydrostatic bearing, which would help the selection and the design of hydrostatic bearings in engineering practice.

关键词： hydrostatic thrust bearing viscosity-temperature characteristic Finite Volume Method (FVM) temperature field

Spatial Variability of Nutrient Properties in Black Soil of Northeast China

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2007年第1期17卷 19-29页

作者： ZHANG Xing-Yi SUI yue-yu ZHANG xu-dong MENG Kai S. J. HERBERT Northeast Institute of Geography and Agroecology Chinese Academy of Sciences Harbin 150081 （China） Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 （China） Heilongjiang University Harbin 150080 （China） Department of Plant Soil and Insect Sciences University of Massachusetts Amherst MA 01003 （USA）

A total of 1400 soil samples from the plow layer （0-20 cm） at an approximate interval of 5 km were collected in the autumn of 2002 over the entire black soil arable crops region to determine the spatial variability of seven variables, such as total organic matter content （OMC）, total N, total P, total K, alkali-dissolvable N （AN）, available P （AP） and available K （AK）, with classical statistics and geostatistical analysis across the entire black soil area in Northeast China. In nonsampled areas ordinary kriging was utilized for interpolation of estimated nutrient determinations. Classical statistics revealed highly significant （P ≤ 0.01） correlations with all seven of the soil properties, except for OMC with AP and total K with AK. In addition, using coefficients of variation, all soil properties, except for total K, were moderately variable. A geostatistical analysis indicated that structural factors, such as parent material, terrain, and water table, were the main causes of the spatial correlations. Strong spatial correlations were noted with OMC, total N, total P, AN, and AP, while they were moderate for total K and AK. The effective spatial autocorrelation of OMC, total N, total P, and AN ranged from 1 037 to 1353 km, whereas the ranges of total K, AP, and AK were only from 6 to 138 km. The fit of the experimental scmi-variograms to the theoretical models indicated that except for AN, kriging could successfully interpolate other six variables. Thns, the geostatistical method used on a large scale could accurately evaluate the spatial variability of most black soil nutrient properties in Northeast China.

关键词： black soil China geostatistics analysis soil survey spatial variability

Clinical research of comprehensive rehabilitation in treating brachial plexus injury patients

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2012年第14期125卷 2516-2520页

作者： ZHOU Jun-ming GU yu-dong xu Xiao-jun ZHANG Shen-yu ZHAO Xin Department of Hand Surgery Huashan Hospital Fudan UniversityKey Laboratory of Hand Reconstruction Ministry of HealthShanghai Key Laboratory of Peripheral Nerve and MicrosurgeryShanghai 200040 China

Background Brachial plexus injury is one of the difficult medical problems in the world. The aim of this study was to observe the clinical therapeutic effect of comprehensive rehabilitation in treating dysfunction after brachial plexus injury. Methods Forty-three cases of dysfunction after brachial plexus injury were divided into two groups randomly. The treatment group, which totaled 21 patients （including 14 cases of total brachial plexus injury and seven cases of branch brachial plexus injury）, was treated with comprehensive rehabilitation including transcutaneous electrical nerve stimulation, mid-frequency electrotherapy, Tuina therapy, and occupational therapy. The control group, which totaled 22 patients （including 16 cases of total brachial plexus injury and six cases of branch brachial plexus injury）, was treated with home-based electrical nerve stimulation and occupational therapy. Each course was of 30 days duration and the patients received four courses totally. After four courses, the rehabilitation effect was evaluated according to the brachial plexus function evaluation standard and electromyogram （EMG） assessment. Results In the treatment group, there was significant difference in the scores of brachial plexus function pre- and post-treatment （P 〈0.01） in both ＂total＂ and ＂branch＂ injury. The scores of two ＂total injury＂ groups had statistical differences （P 〈0.01）, while the scores of two ＂branch injury＂ groups had statistical differences （P 〈0.05） after four courses. EMG suggested that the appearance of regeneration potentials of the recipient nerves in the treatment group was earlier than the control group and had significant differences （P 〈0.05）. Conclusion Comprehensive rehabilitation was more effective in treating dysfunction after brachial plexus injury than nonintegrated rehabilitation.

关键词： brachial plexus injury comprehensive rehabilitation therapeutic effects

在线全文

学校读者我要写书评

暂无评论

随机振动下光学谐振腔腔体形变及变动规律

光学精密工程 2017年第2期25卷 281-288页

作者：于旭东雷雯刘畅国防科技大学光电科学与工程学院湖南长沙410073 海军驻湖南地区军事代表室湖南湘潭411100 空军第五电子对抗团辽宁沈阳110000

鉴于复杂环境会使激光陀螺谐振腔产生变形,从而严重影响激光陀螺的性能,本文利用有限元分析软件ANSYS仿真分析了典型随机振动谱(gRMS=6.6 g)下激光陀螺腔镜3个方向的微小形变量,分别为0.342 5″、0.349 4″和0.215 0″,并结合矩阵光学... 详细信息

鉴于复杂环境会使激光陀螺谐振腔产生变形,从而严重影响激光陀螺的性能,本文利用有限元分析软件ANSYS仿真分析了典型随机振动谱(gRMS=6.6 g)下激光陀螺腔镜3个方向的微小形变量,分别为0.342 5″、0.349 4″和0.215 0″,并结合矩阵光学理论定量得到了谐振腔光阑处的形变量。然后定量分析了不同曲率半径、不同腔长、不同入射角对光学四边形环形谐振腔的影响规律。最后,研究了球面镜-球面镜同时变化以及球面镜-平面镜同时变化下谐振光路的变动规律。实验结果表明,单纯考虑谐振腔的抗振性能,当L处于0~1m,R处于1~8m时,球面镜的曲率半径越小,腔长越短,四边形环形光学谐振腔所受外界环境的影响越小,两个腔镜同时变化时按照一定规律等效成单镜变化。本文研究可以为激光陀螺光学谐振腔的设计提供参考。

关键词：激光陀螺随机振动光学谐振腔腔变规律有限元仿真

在线全文

学校读者我要写书评

暂无评论

蓝宝石晶体的生长方向研究

人工晶体学报 2006年第2期35卷 431-434页

作者：于旭东孙广年浙江巨兴光学材料有限公司衢州324004

本实验采用提拉法,在中频感应加热单晶炉内,进行了不同生长方向蓝宝石晶体的生长工作,分别取[11-20]和[0001]生长的晶体c面(0001)的晶片。通过应力仪、显微观测和X射线衍射等方式对晶片的位错密度等微观缺陷以及晶体结构进行了检测。实... 详细信息

本实验采用提拉法,在中频感应加热单晶炉内,进行了不同生长方向蓝宝石晶体的生长工作,分别取[11-20]和[0001]生长的晶体c面(0001)的晶片。通过应力仪、显微观测和X射线衍射等方式对晶片的位错密度等微观缺陷以及晶体结构进行了检测。实验表明:不同的生长方向生长得到的蓝宝石晶体的质量存在一定的差别,一般情况下,[11-20]方向生长的蓝宝石晶体质量优于[0001]方向生长的晶体。

关键词：提拉法生长方向位错密度衍射晶体结构