对三种舞动幅值的计算方法进行比较,提出采用气象系数法确定导线各个舞动阶次的幅值。以正弦驻波作为导线舞动激励,分别采用线长法、能量法和有限元法(finite element analysis,FEA)计算孤立档导线舞动张力变化值:线长法与有限元法计算...对三种舞动幅值的计算方法进行比较,提出采用气象系数法确定导线各个舞动阶次的幅值。以正弦驻波作为导线舞动激励,分别采用线长法、能量法和有限元法(finite element analysis,FEA)计算孤立档导线舞动张力变化值:线长法与有限元法计算结果基本一致;能量法计算值小于线长法和有限元法,舞动半波数为奇数时,其计算值为其他方法计算值的40%～50%。通过在通用有限元软件ANSYS中建立包含2个独立耐张段和1个独立耐张段的连续多档有限元模型,分析不同档数下耐张塔和直线塔两侧导线舞动张力差的变化规律。分析结果表明:当数不小于4时,档数变化对铁塔两侧导线舞动张力及张力差的影响不大,耐张塔挂点张力差可取两档模型理论计算值的50%;相同档数时,直线塔舞动张力差为耐张塔舞动张力差的12%～25%。基于舞动张力分析结果,提出了杆塔舞动荷载的计算方法。展开更多
Today companies and organizations are using the Web as the main informationdissemination means both at internal and external level. Information dissemination often takes theform of XML documents that are made availabl...Today companies and organizations are using the Web as the main informationdissemination means both at internal and external level. Information dissemination often takes theform of XML documents that are made available at Web servers, or that are actively broadcasted byWeb servers to interested clients. These documents often contain information at different degrees ofsensitivity, therefore a strong XML security platform and mechanism is needed. In this paper wedeveloped CIT/XML security platform and take a close look to syntax and processing of CIT/digitalsignature model, CIT/encryption model, CIT/smart card crypto and SPKI interface security models.Security services such as authentication, integrity and confidentiality to XML documents and non-XMLdocuments, which exchanged among various servers, are provided.展开更多
A 2D axisymmetric bin model is used to conduct idealized numerical experiments of cloud seeding.The simulations are performed for two clouds that differ in their initial wind shear.Results show that,although cloud see...A 2D axisymmetric bin model is used to conduct idealized numerical experiments of cloud seeding.The simulations are performed for two clouds that differ in their initial wind shear.Results show that,although cloud seeding with an ice concentration of 1000 Lin a regime that has relatively high supercooled liquid water can obtain a positive effect,the rainfall enhancement seems more pronounced when the cloud develops in a wind shear environment.In no-shear environment,the change in the microphysical thermodynamic field after seeding shows that,although more graupel is produced via riming and this can increase the surface rainfall intensity,the larger drag force and cooling of melting graupel is unfavorable for the development of cloud.On the contrary,when the cloud develops in a wind shear environment,since the main downdraft is behind the direction of movement of the cloud,its negative effect on precipitation is much weaker.展开更多
Based on the “Ming-Qing Women’s Writings （MQWW）, a digital archive and database” project and the “China Biographical Database （CBDB）” project, which have been collaborating since 2008, this paper uses dif...Based on the “Ming-Qing Women’s Writings （MQWW）, a digital archive and database” project and the “China Biographical Database （CBDB）” project, which have been collaborating since 2008, this paper uses different digital methods to analyse the Ming-Qing women poets’ lives, such as the themes of their poems, their geographical distribution, and their social networks. The aim of this paper is to show researchers various prospects for the integration of digital humanities projects.展开更多
This paper focuses on exporting relational data into extensible markup language (XML). First, the characteristics of both relational schemas represented by E-R diagrams and XML document type definitions (DTDs) are an...This paper focuses on exporting relational data into extensible markup language (XML). First, the characteristics of both relational schemas represented by E-R diagrams and XML document type definitions (DTDs) are analyzed. Secondly, the corresponding mapping rules are proposed. At last an algorithm based on edge tables is presented. There are two key points in the algorithm. One is that the edge table is used to store the information of the relational dictionary, and this brings about the efficiency of the algorithm. The other is that structural information can be obtained from the resulting DTDs and other applications can optimize their query processes using the structural information.展开更多
文摘对三种舞动幅值的计算方法进行比较,提出采用气象系数法确定导线各个舞动阶次的幅值。以正弦驻波作为导线舞动激励,分别采用线长法、能量法和有限元法(finite element analysis,FEA)计算孤立档导线舞动张力变化值:线长法与有限元法计算结果基本一致;能量法计算值小于线长法和有限元法,舞动半波数为奇数时,其计算值为其他方法计算值的40%～50%。通过在通用有限元软件ANSYS中建立包含2个独立耐张段和1个独立耐张段的连续多档有限元模型,分析不同档数下耐张塔和直线塔两侧导线舞动张力差的变化规律。分析结果表明:当数不小于4时,档数变化对铁塔两侧导线舞动张力及张力差的影响不大,耐张塔挂点张力差可取两档模型理论计算值的50%;相同档数时,直线塔舞动张力差为耐张塔舞动张力差的12%～25%。基于舞动张力分析结果,提出了杆塔舞动荷载的计算方法。
文摘Today companies and organizations are using the Web as the main informationdissemination means both at internal and external level. Information dissemination often takes theform of XML documents that are made available at Web servers, or that are actively broadcasted byWeb servers to interested clients. These documents often contain information at different degrees ofsensitivity, therefore a strong XML security platform and mechanism is needed. In this paper wedeveloped CIT/XML security platform and take a close look to syntax and processing of CIT/digitalsignature model, CIT/encryption model, CIT/smart card crypto and SPKI interface security models.Security services such as authentication, integrity and confidentiality to XML documents and non-XMLdocuments, which exchanged among various servers, are provided.
基金This study was jointly supported by the National Key Research and Development Program of China[grant number 2018YFC1507900]the National Natural Science Foundation of China[grant numbers 41875172 and 42075192].
文摘A 2D axisymmetric bin model is used to conduct idealized numerical experiments of cloud seeding.The simulations are performed for two clouds that differ in their initial wind shear.Results show that,although cloud seeding with an ice concentration of 1000 Lin a regime that has relatively high supercooled liquid water can obtain a positive effect,the rainfall enhancement seems more pronounced when the cloud develops in a wind shear environment.In no-shear environment,the change in the microphysical thermodynamic field after seeding shows that,although more graupel is produced via riming and this can increase the surface rainfall intensity,the larger drag force and cooling of melting graupel is unfavorable for the development of cloud.On the contrary,when the cloud develops in a wind shear environment,since the main downdraft is behind the direction of movement of the cloud,its negative effect on precipitation is much weaker.
文摘Based on the “Ming-Qing Women’s Writings （MQWW）, a digital archive and database” project and the “China Biographical Database （CBDB）” project, which have been collaborating since 2008, this paper uses different digital methods to analyse the Ming-Qing women poets’ lives, such as the themes of their poems, their geographical distribution, and their social networks. The aim of this paper is to show researchers various prospects for the integration of digital humanities projects.
文摘This paper focuses on exporting relational data into extensible markup language (XML). First, the characteristics of both relational schemas represented by E-R diagrams and XML document type definitions (DTDs) are analyzed. Secondly, the corresponding mapping rules are proposed. At last an algorithm based on edge tables is presented. There are two key points in the algorithm. One is that the edge table is used to store the information of the relational dictionary, and this brings about the efficiency of the algorithm. The other is that structural information can be obtained from the resulting DTDs and other applications can optimize their query processes using the structural information.
