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Effects of Fe concentration on microstructure and corrosion of Mg-6Al-1Zn-xFe alloys for fracturing balls applications 被引量:7
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作者 Cheng Zhang Liang Wu +5 位作者 Guangsheng Huang Lin Chen Dabiao Xia Bin Jiang Andrej Atrens Fusheng Pan 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2019年第9期2086-2098,共13页
Mg-6 Al-1 Zn-xFe(x = 0,1,3,5 and 7 wt%)alloys were prepared by powder metallurgy and followed by hot extrusion.Majority of Fe element exists as insoluble particles in the alloys.The as-extruded alloys showed higher ... Mg-6 Al-1 Zn-xFe(x = 0,1,3,5 and 7 wt%)alloys were prepared by powder metallurgy and followed by hot extrusion.Majority of Fe element exists as insoluble particles in the alloys.The as-extruded alloys showed higher degradable rates but less stable mechanical properties than as-annealed alloys.Corrosion rate of all the alloys increased with increasing Fe concentration,reaching 2.4 mL cm-2h-1.0.2% yield strength of all the alloys was higher than 150 MPa.In short,Mg-6 Al-1 Zn-xFe alloys have an attractive combination of corrosion and mechanical properties,which holds a bright future for fracturing balls applications. 展开更多
关键词 Mg-6Al-1Zn-xFe alloys Fracturing balls CORROSION Mechanical properties
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BALIS原文传递服务系统的可持续发展研究 被引量:9
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作者 汪永红 黄智武 《图书馆学研究》 CSSCI 北大核心 2014年第2期59-64,共6页
文章在深入分析BALIS原文传递5年服务发展历程的基础上,提出了BALIS原文传递服务系统"一个中心、两个保障、三个重点"的可持续性发展策略,并总结了BALIS原文传递服务系统的发展特色,最后对BALIS原文传递服务系统的未来发展进... 文章在深入分析BALIS原文传递5年服务发展历程的基础上,提出了BALIS原文传递服务系统"一个中心、两个保障、三个重点"的可持续性发展策略,并总结了BALIS原文传递服务系统的发展特色,最后对BALIS原文传递服务系统的未来发展进行了展望。 展开更多
关键词 BAL LS原文传递 发展策略 可持续发展
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Effects of austempering temperature on microstructure and surface residual stress of carbidic austempered ductile iron(CADI) grinding balls 被引量:8
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作者 Jin-hai Liu Peng Xiong +4 位作者 Bin-guo Fu Wei-ting Yang Xue-bo Zhao Zi-ang Han Guo-lu Li 《China Foundry》 SCIE 2018年第3期173-181,共9页
The effects of austempering temperature on microstructure and surface residual stress of carbidic austempered ductile iron (CADI) grinding balls were systematically investigated in this work. The microstructures we... The effects of austempering temperature on microstructure and surface residual stress of carbidic austempered ductile iron (CADI) grinding balls were systematically investigated in this work. The microstructures were oberserved by optical metallography and analyized by X-ray diffraction. The surface residual stress measured by the cutting method is mainly composed of thermal stress and phase transformation stress.The thermal stress in grinding balls was determined by ANSYS simulation technique, and the surface phase transformation stress was obtained by subtracting the simulated surface thermal stress from the measured surface residual stress. Results show that all microstructures consist of ausferrite, white-bright zones (mixture of martensite and austenite), nodular graphite, and carbides. The distribution of ausferrite shows uniform. With the increase of austempering temperature, the volume fraction and carbon content of austenite increase, whereas the amount of white-bright zone decreases. In addition, the surface residual stress increases with the increase of austempering temperature. Only the tension exists at the austempering temperature of 200 ℃, and the pressure exists at the austempering temperature of 220-260 °C. The thermal stress changes from the tension on the inside with the radius of 0-35 mm to the pressure on the outside with the radius of 35-62.5 mm, and the stress balance state presents at the radius of 35 mm. It is also found that the transformation stress is related to the content of carbon-rich austenite, and will reduce by 5.03 MPa accompanied with 1vol.% increase of the austenite.The thermal compressive stress and the transformation tensile stress on the surface both decrease with the increase of the austempering temperature. 展开更多
关键词 CADI grinding balls austempering temperature ANSYS MICROSTRUCTURE residual stress
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Classification of rational holomorphic maps from B^2 into B^N with degree 2 被引量:5
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作者 JI ShanYu 1 & ZHANG Yuan 2 1 Department of Mathematics, University of Houston, Houston, TX 77204, USA 2 Department of Mathematics, University of California at San Diego, La Jolla, CA 92093, USA 《Science China Mathematics》 SCIE 2009年第12期2647-2667,共21页
Rational proper holomorphic maps from the unit ball in C 2 into the unit ball C N with degree 2 are classified, up to automorphisms of balls.
关键词 RATIONAL HOLOMORPHIC MAPS between balls CLASSIFICATION MAPS with DEGREE 2
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体育教育专业设置球类综合课程的构想 被引量:3
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作者 彭健民 张继伯 《广州体育学院学报》 北大核心 2003年第2期91-93,共3页
体育教育专业现行的篮、排、足球三门课程以竞技为中心的分科教学模式已不适合学生的需求和中小学的实际 ,设置球类综合课程是现实的需要。其综合过程应遵循三条准则 :1)还球类运动游戏本原 ;2 )以球类健身知识技能为教学主线 :3 )以学... 体育教育专业现行的篮、排、足球三门课程以竞技为中心的分科教学模式已不适合学生的需求和中小学的实际 ,设置球类综合课程是现实的需要。其综合过程应遵循三条准则 :1)还球类运动游戏本原 ;2 )以球类健身知识技能为教学主线 :3 )以学科重组为综合模式。 展开更多
关键词 体育教育专业 球类综合课程 课程设置 教学模式 运动游戏 健身知识技能
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Enhancing Fire Safety in Commercial Vehicles: Assessing the Efficacy and Advantages of Exploding Fire Extinguishing Balls
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作者 Paul W. Ford 《Journal of Transportation Technologies》 2024年第4期521-548,共28页
Fire incidents in commercial vehicles pose significant risks to passengers, drivers, and cargo. Traditional fire extinguishing systems, while effective, may have limitations in terms of response time, coverage, and hu... Fire incidents in commercial vehicles pose significant risks to passengers, drivers, and cargo. Traditional fire extinguishing systems, while effective, may have limitations in terms of response time, coverage, and human intervention [1]. This study investigates the efficacy of a novel fire suppression technology—the Exploding Fire Extinguishing Ball (EFEB) —as an alternative and complementary fire safety solution for commercial vehicles. The research employs a multidisciplinary approach, encompassing engineering, materials science, fire safety, and human factors analysis. A systematic literature review establishes a comprehensive understanding of existing fire suppression technologies, including EFEBs. Subsequently, this study analyzes the unique features of EFEBs, such as automatic activation, as well as manual activation upon exposure to fire, and their potential to provide rapid, localized, and autonomous fire suppression. The study presents original experimental investigations to assess the performance and effectiveness of EFEBs in various fire scenarios representative of commercial vehicles. Experiments include controlled fires in confined spaces and dynamic simulations to emulate real-world fire incidents. Data on activation times, extinguishing capability, and coverage area are collected and analyzed to compare the efficacy of EFEBs with traditional fire extinguishing methods. Furthermore, this research shows the practical aspects of implementing EFEBs in commercial vehicles. A feasibility study examines the integration challenges, cost-benefit analysis, and potential regulatory implications. The study also addresses the impact of EFEBs on vehicle weight, stability, and overall safety. Human factors and user acceptance are crucial elements in adopting new safety technologies. Therefore, this research utilizes an experimental design to assess the performance and effectiveness of EFEBs in various fire scenarios representative of commercial vehicles. This dissertation presents original controlled experim 展开更多
关键词 Exploding Fire Extinguishing balls Commercial Vehicles Fire Suppression Fire Safety Technology Human Factors Usability Feasibility Study
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One-step direct synthesis of mesoporous aluminosilicates Al-SBA-15 with cage-like macropores by using micrometer-sized aluminum balls 被引量:4
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作者 CAI HuaQiang ZHAO DongYuan 《Science China Chemistry》 SCIE EI CAS 2009年第8期1090-1096,共7页
Ordered mesoporous aluminosilicate Al-SBA-15 materials with cage-like macropores have been synthesized by using micrometer-sized aluminum balls as an Al source,tetraethyl orthosilicate(TEOS) as a silica source,and tri... Ordered mesoporous aluminosilicate Al-SBA-15 materials with cage-like macropores have been synthesized by using micrometer-sized aluminum balls as an Al source,tetraethyl orthosilicate(TEOS) as a silica source,and triblock copolymer Pluronic P123 as a template.The resulting materials were fully characterized by XRD,N2 adsorption,SEM,TEM,ICP-AES,and 27Al MAS-NMR.The products(Al-SBA-15) have ordered two-dimensional(2-D) hexagonal mesostructures(space group p6mm).The calcined Al-SBA-15 materials exhibit disordered macropores with diameters of about 70―80 nm and ordered mesopores with a diameter of ~5 nm,a BET surface area of about 500 m2/g,Si/Al ratio of 40―80,and a ratio of tetrahedral Al to octahedral Al sites of about 2:1.This combination of properties gives these materials potential applications in areas such as adsorption,catalysis and separation. 展开更多
关键词 synthesis mesoporous materials ALUMINUM balls TEMPLATING Al-SBA-15
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在学校开展匹克球运动的若干问题分析 被引量:2
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作者 简伟峰 李凡 苏庆勇 《体育科技文献通报》 2024年第3期201-205,共5页
随着我国经济的不断发展和综合国力的不断增强,身体素质越来越被人们所重视。作为一种新兴运动,匹克球在我国的发展势头迅猛,但由于传入时间较短,有关电子资源和书籍相对匮乏,导致该项目在开展和推广过程中遇到一些疑问或问题不能得到... 随着我国经济的不断发展和综合国力的不断增强,身体素质越来越被人们所重视。作为一种新兴运动,匹克球在我国的发展势头迅猛,但由于传入时间较短,有关电子资源和书籍相对匮乏,导致该项目在开展和推广过程中遇到一些疑问或问题不能得到及时解释。对此,本文系统分析解答了匹克球在学校开展过程中遇到的诸如球场、球、球拍、握拍、两套计分规则等方面的常见问题,旨在为今后学校、社会开展匹克球运动提供参考依据。 展开更多
关键词 匹克球 球场 握拍 常见问题
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Point cloud registration for agriculture and forestry crops based on calibration balls using Kinect V2 被引量:6
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作者 Sanzhang Zhou Feng Kang +2 位作者 Wenbin Li Jiangming Kan Yongjun Zheng 《International Journal of Agricultural and Biological Engineering》 SCIE EI CAS 2020年第1期198-205,共8页
For the process of point cloud registration,and the problem of inaccurate registration due to errors in correspondence between keypoints.In this paper,a registration method based on calibration balls was proposed,the ... For the process of point cloud registration,and the problem of inaccurate registration due to errors in correspondence between keypoints.In this paper,a registration method based on calibration balls was proposed,the trunk,branch,and crown were selected as experimental objects,and three calibration balls were randomly placed around the experimental objects to ensure different distances between two ball centers.Using the Kinect V2 depth camera to collect the point cloud of the experimental scene from four different viewpoints,the PassThrough filter algorithm was used for point cloud filtering in each view of the experimental scenes.The Euclidean cluster extraction algorithm was employed for point cloud clustering and segmentation to extract the experimental object and the calibration ball.The random sample consensus(RANSAC)algorithm was applied to fit the point cloud of a ball and calculate the coordinates of the ball center so that the distance between two ball centers under different viewpoints can be obtained by using the coordinates of the ball center.Comparing the distance between the ball centers from different viewpoints to determine the corresponding relationship between the ball centers from different viewpoints,and then using the singular value decomposition(SVD)method,the initial registration matrix was obtained.Finally,Iterative Closest Point(ICP)and its improved algorithm were used for accurate registration.The experimental results showed that the method of point cloud registration based on calibration balls can solve the problem of corresponding error of keypoints,and can register point clouds from different viewpoints of the same object.The registration method was evaluated by using the registration running time and the fitness score.The final registration running time of different experimental objects was not more than 6.5 s.The minimum fitness score of the trunk was approximately 0.0001,the minimum fitness score of the branch was approximately 0.0001,and the minimum fitness score of the crown was 展开更多
关键词 point cloud registration calibration balls Kinect V2 ICP
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LINEAR SINGULAR INTEGRAL EQUATION ON DOMAINS COMPOSED BY BALLS 被引量:3
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作者 黄玉笙 林良裕 《Acta Mathematica Scientia》 SCIE CSCD 2006年第1期145-151,共7页
For domains composed by balls in C^n, this paper studies the boundary behaviour of Cauchy type integrals with discrete holomorphic kernels and the corresponding linear singular integral equation on each piece of smoot... For domains composed by balls in C^n, this paper studies the boundary behaviour of Cauchy type integrals with discrete holomorphic kernels and the corresponding linear singular integral equation on each piece of smooth lower dimensional edges on the boundary of the domain. 展开更多
关键词 Domains composed by balls discrete kernel linear singular integral equation
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Rational holomorphic maps from B^2 into B^N with degree 2 被引量:3
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作者 CHEN Zhihua, Jl Shanyu & XU Dekang Department of Mathematics, Tongji University, Shanghai 200092, China Department of Mathematics, University of Houston, Houston, TX 77204, USA 《Science China Mathematics》 SCIE 2006年第11期1504-1522,共19页
Rational proper holomorphic maps from the unit ball in C2 into the unit ball CN with degree 2 are studied. Any such map must be equivalent to one of the four types of maps.
关键词 RATIONAL HOLOMORPHIC MAPS BETWEEN balls.
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Some problems on balls and spheres for Brownian motion 被引量:3
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作者 尹传存 吴荣 《Science China Mathematics》 SCIE 1996年第6期572-582,共11页
<正> The distributions of the sojourn time of a ball and hitting time for a sphere for Brownian motion starting at any point in space, as well as the joint distributions of the maximum excursion before last exit... <正> The distributions of the sojourn time of a ball and hitting time for a sphere for Brownian motion starting at any point in space, as well as the joint distributions of the maximum excursion before last exit sphere and first instance of attaining such a maximum for Brownian motion starting at the inside of a ball are given. 展开更多
关键词 BROWNIAN motion sojourn TIMES hitting TIMES maximum EXCURSIONS balls sphere.
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Balls into bins分配器算法 被引量:1
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作者 李航 郭敬林 +1 位作者 刘西洋 陈平 《系统工程与电子技术》 EI CSCD 北大核心 2005年第1期115-116,共2页
针对传统的bitmap分配器算法中没有反馈机制,导致搜索不能很好地适应各种情况的问题。分析得到bitmap分配器算法中空闲块的搜索问题实际上是一个负载平衡的问题,因此将ballsintobins的负载平衡问题的研究结果应用在bitmap分配器上。将bi... 针对传统的bitmap分配器算法中没有反馈机制,导致搜索不能很好地适应各种情况的问题。分析得到bitmap分配器算法中空闲块的搜索问题实际上是一个负载平衡的问题,因此将ballsintobins的负载平衡问题的研究结果应用在bitmap分配器上。将bitmap分成不同的区,从中选出负载量小的区进行分析,经对比分析和对C3I系统的实际检验表明,这种分配器算法的确优于传统的bitmap分配器算法。 展开更多
关键词 balls into bins分配器 bitmap分配器 算法
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INVERSE OPALINE STRUCTURE TITANIA PHOTONIC CRYSTALS BY FUNCTIONALLY MODIFIED COLLOIDAL CRYSTALS TEMPLATING 被引量:2
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作者 Hong-yu Li Zhi-qiang Chen +2 位作者 Hai-qiao Wang Bo Meng Xiao-yu Li 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2007年第2期217-220,共4页
Ordered macroporous titania photonic crystals (PCs) and photonic balls were fabricated by functional modified polymer colloidal crystals. The TiO2 PCs and balls formed through this method exhibit no cracks and lacun... Ordered macroporous titania photonic crystals (PCs) and photonic balls were fabricated by functional modified polymer colloidal crystals. The TiO2 PCs and balls formed through this method exhibit no cracks and lacunae in large areas on their surface and their inner structures. 展开更多
关键词 Photonic crystals Photonic balls Ordered macroporous titania Polymer colloidal crystals.
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Chemical oxygen demand oxidation via sustained-release persulfate balls: a rate-compatibility study of flow velocity, releasing, and oxidation
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作者 Bate BATE Danting ZHANG +3 位作者 Jianshe YE Min XIA Yixin YANG Shuai ZHANG 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2024年第9期749-762,共14页
Identification of chemical oxygen demand(COD)in municipal solid waste(MSW)landfill leachates is a challenging problem.This paper investigated the feasibility of using sodium persulfate(PS),a strong oxidant,as a permea... Identification of chemical oxygen demand(COD)in municipal solid waste(MSW)landfill leachates is a challenging problem.This paper investigated the feasibility of using sodium persulfate(PS),a strong oxidant,as a permeable reactive barrier(PRB)filling material.Firstly,sustained-release persulfate balls were manufactured to adjust the release rate of persulfate,the oxidation agent.In addition,Fe(II)-loaded activated carbon(Fe-AC)was used to help with an even distribution of Fe(II)in the porous medium(PRB in this case).Then,the oxidation efficiency and kinetic rate of COD removal by the sustained-release balls were subjected to batch tests.A mass ratio of 1:1.4:0.24:0.7 for PS:cement:sand:water was the most efficient for COD removal(95%).The breakthrough curve for a 5 mm sustained-release ball revealed that the retardation factor was 1.27 and that the hydrodynamic dispersion coefficient was 15.6 cm^(2)/d.The corresponding half-life of COD oxidation was 0.43 d,which was comparable with the half-life of PS release from sustained-release balls(0.56 d).The sustained-release persulfate balls were shown to be an economical material with a simple recipe and production method when catalyzed by Fe-AC.Compared with cutting-edge methods,sustained-release balls used in PRBs offer significant advantages in terms of both effectiveness and economy for the preparation of sustained-release and catalytic materials.These results verified the feasibility of using sustained-release persulfate balls as a PRB material for COD removal. 展开更多
关键词 Chemical oxygen demand(COD) Sodium persulfate(PS) Sustained-release balls Permeable reactive barrier(PRB) Fe(II)-loaded activated carbon(Fe-AC)
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浅谈BALIS原文传递服务之发展对策 被引量:4
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作者 黄智武 丁永玲 《图书馆论坛》 CSSCI 北大核心 2010年第5期105-106,131,共3页
BALIS原文传递服务启动两年来,经历着筹建、宣传和发展等阶段,文章试图在回眸BALIS原文传递服务发展历程的基础上,介绍一些BALIS原文传递服务的发展对策,力求为探讨地域性原文传递服务发展对策起到抛砖引玉的作用。
关键词 BALIS 原文传递 发展对策
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Flatness of CR submanifolds in a sphere 被引量:1
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作者 JI ShanYu 1, & YUAN Yuan 2 1 Department of Mathematics, University of Houston, Houston, TX 77204, USA 2 Department of Mathematics, Rutgers University, Piscataway, NJ 08854, USA 《Science China Mathematics》 SCIE 2010年第3期701-718,共18页
In Euclidean geometry, for a real submanifold M in E n+a , M is a piece of E n if and only if its second fundamental form is identically zero. In projective geometry, for a complex submanifold M in CP n+a , M is a pie... In Euclidean geometry, for a real submanifold M in E n+a , M is a piece of E n if and only if its second fundamental form is identically zero. In projective geometry, for a complex submanifold M in CP n+a , M is a piece of CP n if and only if its projective second fundamental form is identically zero. In CR geometry, we prove the CR analogue of this fact in this paper. 展开更多
关键词 CR SUBMANIFOLDS SPHERE CR second fundamental form proper HOLOMORPHIC MAPPINGS between balls
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Obstructing fungal cholangitis complicating metal biliary stent placement in pancreatic cancer 被引量:1
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作者 Brian Story Michael Gluck 《World Journal of Gastroenterology》 SCIE CAS CSCD 2010年第24期3083-3086,共4页
Biliary obstructions can lead to infections of the biliary system, particularly in patients with occluded biliary stents. Fungal organisms are frequently found in bili-ary aspirates of patients who have been on antibi... Biliary obstructions can lead to infections of the biliary system, particularly in patients with occluded biliary stents. Fungal organisms are frequently found in bili-ary aspirates of patients who have been on antibiotics and have stents; however, fungal masses, or "balls", that fully obstruct the biliary system are uncommon and exceedingly diff icult to eradicate. We present 4 cases of obstructing fungal cholangitis in patients who had metal biliary stents placed for pancreatic malignancies, and subsequently required aggressive antifungal administration along with endoscopic and radiologic interventions. This report also reviews approaches previously undertaken to manage severe obstructing fungal cholangitis. 展开更多
关键词 Obstructing fungal cholangitis Biliary stents Fungal balls Pancreatic cancer Biliary obstruction
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A New Shaping Model for Green Ceramic Balls
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作者 REN Cheng-zu, WU Zhen-yong, JIN Xin-ming, WANG Chun-jie, XU Qiang (Institute of Mechanical Engineering, Tianjin University, Tianjin 300072, China) 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期35-36,共2页
The shaping quality of green ceramic balls is directly related to the efficiency and cost of later machining for the ceramic balls. Until now the shaping for green ceramic balls is still conducted by handwork. In this... The shaping quality of green ceramic balls is directly related to the efficiency and cost of later machining for the ceramic balls. Until now the shaping for green ceramic balls is still conducted by handwork. In this paper, a new shaping model for green ceramic balls was designed. In the new model, two grinding wheels with the same generator line as circular arc are mounted on symmetry, and their axes are parallel. The green ball can be put in the enveloping space formed by the two grinding wheels. The radius of generator line must be equal to or slightly greater than the final radius of the green balls, which can ensure that an ideal sphere can be enveloped by the generator of grinding wheel as grinding the green body surface with the wheels. One of the two wheels rotates in upward direction at high speed v 1, conversely, the other wheel rotates in downward direction at low speed v 2, and a cluster of compressed air is exerted on the green ball above for canceling out the force acting upon the green ball created by the action of the grinding wheel revolving at high speed and avoiding that the green ball jumps off its station. Because of the randomness of the distributions of abrasive grains on the surface of grinding wheels, the size and shape of the abrasive grains, and the posture of green body when falling into the grinding space, the values and directions of the resultant forces and torques exerted on the body, caused by the tow wheels, are random, the rotation of green body is irregular under the actions of the compressed air and the wheels. The irregularity of rotation can ensure an ideal sphere in theory. Experiment researches indicate that the new shaping model can improve the spherical deviations and the size distribution of the green ceramic balls, raise the production, and reduce the costs. The spherical deviations can be improved to 0.04 mm easily. It can be observed by SEM that there is no crack in the surface of sintered ceramic balls shaped with the new model in green blank. 展开更多
关键词 ceramic balls green SHAPING spherical deviation
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涡旋压缩机滚珠防自转机构动力特性研究 被引量:3
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作者 郑尚书 李京京 +2 位作者 李超 赵嫚 柴宝堆 《石油化工设备》 CAS 2020年第5期21-27,共7页
针对涡旋压缩机滚珠防自转机构的动力特性问题,建立了滚珠防自转机构分析模型,基于滚珠防自转机构的工作原理,从运动学和机构学角度对滚珠进行受力分析,建立了滚珠力学模型,应用三维建模软件和有限元分析软件ANSYS,建立了单个滚珠和动... 针对涡旋压缩机滚珠防自转机构的动力特性问题,建立了滚珠防自转机构分析模型,基于滚珠防自转机构的工作原理,从运动学和机构学角度对滚珠进行受力分析,建立了滚珠力学模型,应用三维建模软件和有限元分析软件ANSYS,建立了单个滚珠和动、静导轨的三维模型,通过ANSYS计算得出滚珠和动、静导轨的应力和变形云图,并对滚珠的变形和应力云图进行分析,同时对滚珠在交变载荷作用下的疲劳强度及疲劳寿命进行了分析讨论。研究结果表明,最大应力和变形发生在滚珠和滚道接触区域,疲劳寿命分析结果表明滚珠能长时间稳定工作。 展开更多
关键词 涡旋压缩机 滚珠 有限元法 变形 应力 疲劳强度 研究
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