Aiming at the discontinuous traction on contact elements of roller bearing,new concepts of sub- and micro-element are put forward. In the sub-element and micro-element,traction influence coefficient has been modified,...Aiming at the discontinuous traction on contact elements of roller bearing,new concepts of sub- and micro-element are put forward. In the sub-element and micro-element,traction influence coefficient has been modified, which is calculated by the former boundary elementmethod (BEM) with roller bearing load. Hence, three-dimensional distribution of load on rollerbearing is calculated accurately. In practice, it has been proved that this method has highercalculation accuracy. An effective numerical method is offered for analyzing load characteristics ofroller bearing to improve service longevity of roller bearing and operation efficiency of rollingmill.展开更多
To study the effect of cultivation system （conventional and organic） on potato tuber components, 42 parameters （anti-nutritives, micro- and macro-elements and 23 metabolites） were studied in three multi-resistant ...To study the effect of cultivation system （conventional and organic） on potato tuber components, 42 parameters （anti-nutritives, micro- and macro-elements and 23 metabolites） were studied in three multi-resistant Hungarian potato varieties for three years in 2007-2009. Discriminant analysis of data proved that all investigated factors （farming technology, genotype and season/year） had significant effect on metabolites. Reversed phase high performance liquid chromatographic （HPLC-DAD, HPLC-MS） and elemental analysis methods have been adapted to quantify the major components, i.e., steroidal alkaloids, nitrite, nitrate, sugars, amino acids and micro-elements, in potato tubers. The absolute amount and changes of tuber components were influenced differentially by the technology, genotype and season in a complex manner. Any examined component, except nitrate content, was found to be significantly higher or lower consistently in relation to the production practice （organic or conventional） during the three years trials. Under the examined circumstances, no consequent positive effect of organic fanning on the total amount of anti-nutritive components, vitamins or micro- and macro-elements of potato tubers could be proven.展开更多
定子槽漏感是定子无轭模块化(yokeless and segmented,YASA)轴向磁通永磁电机电感的主要分量,会降低电机的功率因数和最大输出转矩。该文提出定子槽内微小单元磁场能量法计算YASA电机的定子槽漏感,通过建立计及铁心饱和影响的二维等效...定子槽漏感是定子无轭模块化(yokeless and segmented,YASA)轴向磁通永磁电机电感的主要分量,会降低电机的功率因数和最大输出转矩。该文提出定子槽内微小单元磁场能量法计算YASA电机的定子槽漏感,通过建立计及铁心饱和影响的二维等效磁网络模型准确计算槽内微小单元储存的磁场能量,进而计算定子槽漏感。基于所提出的方法,进一步研究定子结构参数以及极槽配合对YASA电机定子槽漏感的影响规律。有限元仿真和实验结果表明,该文所提出的YASA电机定子槽漏感计算方法的可行性和准确性。展开更多
稀土元素会对橡胶的性能造成影响,需加强监控。通过系统分析消解试剂、消解温度以及消解时间等因素对检测分析的影响,对设备工作功率、步距深度、冷却气流速、辅助气流速、雾化气流速等质谱参数进行优化筛选,利用在线内标手段校正基体...稀土元素会对橡胶的性能造成影响,需加强监控。通过系统分析消解试剂、消解温度以及消解时间等因素对检测分析的影响,对设备工作功率、步距深度、冷却气流速、辅助气流速、雾化气流速等质谱参数进行优化筛选,利用在线内标手段校正基体效应和信号漂移等问题,利用微敞开石墨消解技术结合电感耦合等离子体质谱仪,构建了测定天然橡胶制品中16种稀土元素含量的方法。微敞开石墨消解橡胶制品的较优处理条件以6 mL HNO_(3)、1 mL HClO_(4)和4 mL HF为消解试剂,采用三阶程序升温,消解最高温度至180℃,保温180 min。结果表明,稀土元素的检出限为0.0002~0.001 mg/kg,方法加标回收率在71.1%~90.9%,相对标准偏差RSD在3.8%~9.2%,各元素的标准曲线线性关系良好。与传统方法相比,微敞开石墨消解技术操作简便,可按照设定程序自动完成消解全过程,无需单独赶酸,工作效率较高,且具有成本低、检测范围宽、检出限低、处理效率高等优点,适用于橡胶制品中稀土元素的高通量检测。展开更多
剪切型断裂是岩土工程中常见的破坏模式,了解剪切破坏机理并准确预测剪切型裂纹的萌生、扩展过程对保障工程结构的安全性与稳定性具有重要意义.文章建立了基于比例边界有限元法(scaled boundary finite element methods,SBFEM)和非局部...剪切型断裂是岩土工程中常见的破坏模式,了解剪切破坏机理并准确预测剪切型裂纹的萌生、扩展过程对保障工程结构的安全性与稳定性具有重要意义.文章建立了基于比例边界有限元法(scaled boundary finite element methods,SBFEM)和非局部宏-微观损伤模型的剪切型裂纹动态开裂模拟方法,定义了基于偏应变概念的物质点对的正伸长量,可作为预测剪切型裂纹扩展行为的动态开裂准则,一点的损伤定义为该点影响域范围内连接的物质键损伤的加权平均值,而物质键的损伤则与基于偏应变概念的物质点对的正伸长量相关联,并引入能量退化函数建立结构域几何拓扑损伤与能量损失之间的关系,将拓扑损伤与应力应变联系起来,通过能量退化函数修正了SBFEM的刚度系数矩阵,得到了子域在损伤状态下的刚度矩阵,推导了考虑结构损伤的SBFEM动力控制方程,采用Newmark隐式算法对控制方程进行时间离散.最后,通过3个典型算例验证了建议的模型可较好地模拟剪切型断裂问题,能够很好地捕捉剪切型裂纹的扩展路径,并得到较为准确的载荷-位移曲线.展开更多
基金This project is supported by National Natural Science Foundation of China (No.50205004, No. 50075075).
文摘Aiming at the discontinuous traction on contact elements of roller bearing,new concepts of sub- and micro-element are put forward. In the sub-element and micro-element,traction influence coefficient has been modified, which is calculated by the former boundary elementmethod (BEM) with roller bearing load. Hence, three-dimensional distribution of load on rollerbearing is calculated accurately. In practice, it has been proved that this method has highercalculation accuracy. An effective numerical method is offered for analyzing load characteristics ofroller bearing to improve service longevity of roller bearing and operation efficiency of rollingmill.
文摘To study the effect of cultivation system （conventional and organic） on potato tuber components, 42 parameters （anti-nutritives, micro- and macro-elements and 23 metabolites） were studied in three multi-resistant Hungarian potato varieties for three years in 2007-2009. Discriminant analysis of data proved that all investigated factors （farming technology, genotype and season/year） had significant effect on metabolites. Reversed phase high performance liquid chromatographic （HPLC-DAD, HPLC-MS） and elemental analysis methods have been adapted to quantify the major components, i.e., steroidal alkaloids, nitrite, nitrate, sugars, amino acids and micro-elements, in potato tubers. The absolute amount and changes of tuber components were influenced differentially by the technology, genotype and season in a complex manner. Any examined component, except nitrate content, was found to be significantly higher or lower consistently in relation to the production practice （organic or conventional） during the three years trials. Under the examined circumstances, no consequent positive effect of organic fanning on the total amount of anti-nutritive components, vitamins or micro- and macro-elements of potato tubers could be proven.
文摘定子槽漏感是定子无轭模块化(yokeless and segmented,YASA)轴向磁通永磁电机电感的主要分量,会降低电机的功率因数和最大输出转矩。该文提出定子槽内微小单元磁场能量法计算YASA电机的定子槽漏感,通过建立计及铁心饱和影响的二维等效磁网络模型准确计算槽内微小单元储存的磁场能量,进而计算定子槽漏感。基于所提出的方法,进一步研究定子结构参数以及极槽配合对YASA电机定子槽漏感的影响规律。有限元仿真和实验结果表明,该文所提出的YASA电机定子槽漏感计算方法的可行性和准确性。
文摘稀土元素会对橡胶的性能造成影响,需加强监控。通过系统分析消解试剂、消解温度以及消解时间等因素对检测分析的影响,对设备工作功率、步距深度、冷却气流速、辅助气流速、雾化气流速等质谱参数进行优化筛选,利用在线内标手段校正基体效应和信号漂移等问题,利用微敞开石墨消解技术结合电感耦合等离子体质谱仪,构建了测定天然橡胶制品中16种稀土元素含量的方法。微敞开石墨消解橡胶制品的较优处理条件以6 mL HNO_(3)、1 mL HClO_(4)和4 mL HF为消解试剂,采用三阶程序升温,消解最高温度至180℃,保温180 min。结果表明,稀土元素的检出限为0.0002~0.001 mg/kg,方法加标回收率在71.1%~90.9%,相对标准偏差RSD在3.8%~9.2%,各元素的标准曲线线性关系良好。与传统方法相比,微敞开石墨消解技术操作简便,可按照设定程序自动完成消解全过程,无需单独赶酸,工作效率较高,且具有成本低、检测范围宽、检出限低、处理效率高等优点,适用于橡胶制品中稀土元素的高通量检测。
文摘剪切型断裂是岩土工程中常见的破坏模式,了解剪切破坏机理并准确预测剪切型裂纹的萌生、扩展过程对保障工程结构的安全性与稳定性具有重要意义.文章建立了基于比例边界有限元法(scaled boundary finite element methods,SBFEM)和非局部宏-微观损伤模型的剪切型裂纹动态开裂模拟方法,定义了基于偏应变概念的物质点对的正伸长量,可作为预测剪切型裂纹扩展行为的动态开裂准则,一点的损伤定义为该点影响域范围内连接的物质键损伤的加权平均值,而物质键的损伤则与基于偏应变概念的物质点对的正伸长量相关联,并引入能量退化函数建立结构域几何拓扑损伤与能量损失之间的关系,将拓扑损伤与应力应变联系起来,通过能量退化函数修正了SBFEM的刚度系数矩阵,得到了子域在损伤状态下的刚度矩阵,推导了考虑结构损伤的SBFEM动力控制方程,采用Newmark隐式算法对控制方程进行时间离散.最后,通过3个典型算例验证了建议的模型可较好地模拟剪切型断裂问题,能够很好地捕捉剪切型裂纹的扩展路径,并得到较为准确的载荷-位移曲线.
