In order to provide an effective way to create descriptive records for electronic resources and the options to assist librarians in providing their users with enhanced access to Web resources,OCLC has developed anothe...In order to provide an effective way to create descriptive records for electronic resources and the options to assist librarians in providing their users with enhanced access to Web resources,OCLC has developed another new product of cataloging service named CORC.The characteristics of CORC are detailed in this paper based on the author’s experience of using CORC in the United States.Then the paper provides some suggestions for improving the sharing of cooperatively cataloged Web resources in China.展开更多
高温超导CORC(conductor on round core)电缆失超时的热负荷严重威胁了低温系统和电缆本体的安全稳定运行。受微米级超导薄膜制备工艺等的影响,CORC电缆并绕的多根高温超导带材不均匀。为分析不均匀临界电流对CORC电缆失超特性的影响,...高温超导CORC(conductor on round core)电缆失超时的热负荷严重威胁了低温系统和电缆本体的安全稳定运行。受微米级超导薄膜制备工艺等的影响,CORC电缆并绕的多根高温超导带材不均匀。为分析不均匀临界电流对CORC电缆失超特性的影响,该文搭建了基于三维TA方程的有限元模型。以降维的带材曲面为求解区域,以等效的电流密度为求解变量,失超模型在同一几何中表达超导和常导两种属性,构建电流和电势两种约束。在导体域建立降维的热模型,用以考虑损耗和传热的影响;在全局建立等效的电路模型,用以控制并联导体的分流。进一步地,耦合模型考虑温度依赖的接头电阻以模拟CORC电缆带材的烧断和电流的突变。结果表明,非均匀高温超导带材影响了电流重分配的动态响应,加快了局部失超的发展过程。展开更多
CORC(Conductor On Round Core)型电缆在高场下具有高载流和良好的机械性能,是制备聚变堆高场CS磁体最具潜力的电缆结构之一。但在制备过程中的穿缆拉力与运行过程中电磁力在电缆上的轴向分力会导致电缆性能发生衰退。为了研究CORC型电...CORC(Conductor On Round Core)型电缆在高场下具有高载流和良好的机械性能,是制备聚变堆高场CS磁体最具潜力的电缆结构之一。但在制备过程中的穿缆拉力与运行过程中电磁力在电缆上的轴向分力会导致电缆性能发生衰退。为了研究CORC型电缆在液氮、自场环境下临界电流与拉力、应变的关系,设计并搭建了一套电缆轴向拉伸通电测试装置,对基于上海超导YBCO带材制备的CORC哑缆进行测试,研究结果表明,在0~9 kN递增的轴向拉力下,n值呈均匀减小趋势。以95%IC0点作为临界电流衰退点,样品1的临界拉力为5 kN、临界应变为2.70%;样品2的临界拉力为7.4 kN、临界应变为7.20%。研究结果将为CORC型电缆穿缆工艺与运行工况提供数据支持。展开更多
According to engineering experience,the axial shrinkage caused by the refrigerant seriously endangers the performance of long‐distance conductor on round core(CORC)cables.Since outage maintenance of high‐temperature...According to engineering experience,the axial shrinkage caused by the refrigerant seriously endangers the performance of long‐distance conductor on round core(CORC)cables.Since outage maintenance of high‐temperature superconducting(HTS)cables is inevitable,providing appropriate compensation for cyclic temperature is one of the key technologies in the actual application of power cables.Therefore,this paper presents an analytical solution for hollow CORC cables under thermo‐mechanical loads.First,regarded as an axisymmetric composite structure,the radial temperature distribution of CORC cable under Dirichlet boundary or mixed boundary conditions was calculated.Then,assuming cable ends were axially fixed,a recursive method without variables is used to evaluate its displacement,strains,and stresses.Then,an algebraic method with axial strain as a variable is developed to analyze the mechanical behavior of the CORC cable more directly.Finally,concluded from the above derivation,a matrix equation is constructed based on continuity equations and boundary conditions,which applies to isotropic and orthotropic materials with orientations.Calculation results show that the analytical solution agrees with finite element method(FEM)results.Compared to the trial results of a 360 m CORC cable,the calculation error of axial shrinkage is within 1.63 cm,and the relative error is within 6.1%.In addition,the recursive method is the fastest to calculate axial strain,while the matrix method has a significant efficiency advantage in calculating the stresses and strains of each layer.展开更多
对网络资源实行书目控制是对其进行开发、利用的有效途径之一。网络资源数量大、增长快、稳定性小,唯有走合作编目之路才能达到事半功倍的效果。OCLC 顺应网络资源发展的趋势推出 CORC 计划,把“编目资源共享”的概念引入网络资源的组...对网络资源实行书目控制是对其进行开发、利用的有效途径之一。网络资源数量大、增长快、稳定性小,唯有走合作编目之路才能达到事半功倍的效果。OCLC 顺应网络资源发展的趋势推出 CORC 计划,把“编目资源共享”的概念引入网络资源的组织与控制,其中颇有值得我们思索与借鉴的地方。展开更多
文摘In order to provide an effective way to create descriptive records for electronic resources and the options to assist librarians in providing their users with enhanced access to Web resources,OCLC has developed another new product of cataloging service named CORC.The characteristics of CORC are detailed in this paper based on the author’s experience of using CORC in the United States.Then the paper provides some suggestions for improving the sharing of cooperatively cataloged Web resources in China.
文摘高温超导CORC(conductor on round core)电缆失超时的热负荷严重威胁了低温系统和电缆本体的安全稳定运行。受微米级超导薄膜制备工艺等的影响,CORC电缆并绕的多根高温超导带材不均匀。为分析不均匀临界电流对CORC电缆失超特性的影响,该文搭建了基于三维TA方程的有限元模型。以降维的带材曲面为求解区域,以等效的电流密度为求解变量,失超模型在同一几何中表达超导和常导两种属性,构建电流和电势两种约束。在导体域建立降维的热模型,用以考虑损耗和传热的影响;在全局建立等效的电路模型,用以控制并联导体的分流。进一步地,耦合模型考虑温度依赖的接头电阻以模拟CORC电缆带材的烧断和电流的突变。结果表明,非均匀高温超导带材影响了电流重分配的动态响应,加快了局部失超的发展过程。
基金supported by the National Key R&D Program of China under Grant 2018YFA0704300.
文摘According to engineering experience,the axial shrinkage caused by the refrigerant seriously endangers the performance of long‐distance conductor on round core(CORC)cables.Since outage maintenance of high‐temperature superconducting(HTS)cables is inevitable,providing appropriate compensation for cyclic temperature is one of the key technologies in the actual application of power cables.Therefore,this paper presents an analytical solution for hollow CORC cables under thermo‐mechanical loads.First,regarded as an axisymmetric composite structure,the radial temperature distribution of CORC cable under Dirichlet boundary or mixed boundary conditions was calculated.Then,assuming cable ends were axially fixed,a recursive method without variables is used to evaluate its displacement,strains,and stresses.Then,an algebraic method with axial strain as a variable is developed to analyze the mechanical behavior of the CORC cable more directly.Finally,concluded from the above derivation,a matrix equation is constructed based on continuity equations and boundary conditions,which applies to isotropic and orthotropic materials with orientations.Calculation results show that the analytical solution agrees with finite element method(FEM)results.Compared to the trial results of a 360 m CORC cable,the calculation error of axial shrinkage is within 1.63 cm,and the relative error is within 6.1%.In addition,the recursive method is the fastest to calculate axial strain,while the matrix method has a significant efficiency advantage in calculating the stresses and strains of each layer.
