电推进羽流诊断系统(Electric Propulsion Plume Diagnostic System,EPPDS)是由探针组件、移动平台和电控单元组成的用于空间电推进羽流特征参数诊断的自研设备,产品规定的可靠性指标要求平均故障间隔时间(Mean Time Between Failures,M...电推进羽流诊断系统(Electric Propulsion Plume Diagnostic System,EPPDS)是由探针组件、移动平台和电控单元组成的用于空间电推进羽流特征参数诊断的自研设备,产品规定的可靠性指标要求平均故障间隔时间(Mean Time Between Failures,MTBF)检验上限θ0≥5000 h。按照系统串并联模型及寿命指数分布模型的MTBF可靠性预计理论,给出了EPPDS的MTBF预计流程,进行了EPPDS各模块MTBF预计,系统MTBF预计值为1.059×10^(4) h。按照GJB 889短时高风险定时方案完成3台EPPDS 1833 h的可靠性验证试验,试验结果表明电控单元输出的法拉第探针、朗缪尔探针和阻滞势分析仪的偏置电压和扫描电压参数均满足合格判据。该方法可用于电子机械产品的MTBF预计和验证。展开更多
This study examines the depth of information regarding Female Genital Mutilation (FGM)/Female Cutting (FC) present in US medical textbooks. According to Klein et al. (2018) [1], despite substantial attention regarding...This study examines the depth of information regarding Female Genital Mutilation (FGM)/Female Cutting (FC) present in US medical textbooks. According to Klein et al. (2018) [1], despite substantial attention regarding the effects of FGM, this practice is still ongoing all over the world. Healthcare providers are very important actors who need to understand FGM in order to provide care to girls and women subjected to it, but the small amount of existing work in this area shows a low level of knowledge and training about FGM/FC among U.S. physicians. The Center for Disease Control and Prevention (CDC) first published the estimated number of girls at risk of FGM/FC in the U.S. to be about 168,000 in 1997;that number had increased to 513,000 girls in the US by 2012 (according to Goldberg et al.) In this study, a small sample of medical textbooks were analyzed for the degree to which the textbooks include information regarding FGM/FC. The results of this study show that US medical textbooks do not include information regarding FGM/FC, suggesting that most medical providers don’t have knowledge and training about FGM/FC. The inadequate information on FGM/FC in medical textbooks reflects a culturally biased lack of recognition of the number of girls and women affected in the US. This maintains an ongoing pattern of silence that reinforces gender inequality. Considering the inadequate information covered in US medical textbooks on FGM/FC, and the concordant lack of provider training to provide advice and care to affected girls and women, incorrect and missed diagnoses may lead to harm to victims of FGM/FC. Providers would be better equipped to care for women and girls if their medical training included information regarding FGM/FC.展开更多
TBM钢拱架是用于隧道掘进开挖最重要的支护构件之一,其安装效率对隧道的稳定性及人员的安全性有着重要影响。为了减小TBM在隧道掘进过程中产生的振动造成钢拱架拼装系统安装效率低的不利影响,文中将约束理论(Theory of Constraints, TOC...TBM钢拱架是用于隧道掘进开挖最重要的支护构件之一,其安装效率对隧道的稳定性及人员的安全性有着重要影响。为了减小TBM在隧道掘进过程中产生的振动造成钢拱架拼装系统安装效率低的不利影响,文中将约束理论(Theory of Constraints, TOC)和发明问题解决理论(Theory of Inventive Problem Solving, TRIZ)进行融合,应用于钢拱架拼装机构的减振设计。首先,采用TOC对钢拱架拼装机构的不合理约束进行系统分析;然后,运用TRIZ求解输出多种设计方案,结合工程实际对不同方案进行评估分析;最后,提出合理的问题解决方案。通过TOC/TRIZ理论的融合应用解决了钢拱架拼装机构的振动问题,为相关隧道工程装备的设计提供了参考。展开更多
Buckling and postbuckling characteristics of laminated graphene-enhanced composite(GEC)truncated conical shells exposed to torsion under temperature conditions using finite element method(FEM)simulation are presented ...Buckling and postbuckling characteristics of laminated graphene-enhanced composite(GEC)truncated conical shells exposed to torsion under temperature conditions using finite element method(FEM)simulation are presented in this study.In the thickness direction,the GEC layers of the conical shell are ordered in a piece-wise arrangement of functionally graded(FG)distribution,with each layer containing a variable volume fraction for graphene reinforcement.To calculate the properties of temperaturedependent material of GEC layers,the extended Halpin-Tsai micromechanical framework is used.The FEM model is verified via comparing the current results obtained with the theoretical estimates for homogeneous,laminated cylindrical,and conical shells,the FEM model is validated.The computational results show that a piece-wise FG graphene volume fraction distribution can improve the torque of critical buckling and torsional postbuckling strength.Also,the geometric parameters have a critical impact on the stability of the conical shell.However,a temperature rise can reduce the crucial torsional buckling torque as well as the GEC laminated truncated conical shell’s postbuckling strength.展开更多
文摘This study examines the depth of information regarding Female Genital Mutilation (FGM)/Female Cutting (FC) present in US medical textbooks. According to Klein et al. (2018) [1], despite substantial attention regarding the effects of FGM, this practice is still ongoing all over the world. Healthcare providers are very important actors who need to understand FGM in order to provide care to girls and women subjected to it, but the small amount of existing work in this area shows a low level of knowledge and training about FGM/FC among U.S. physicians. The Center for Disease Control and Prevention (CDC) first published the estimated number of girls at risk of FGM/FC in the U.S. to be about 168,000 in 1997;that number had increased to 513,000 girls in the US by 2012 (according to Goldberg et al.) In this study, a small sample of medical textbooks were analyzed for the degree to which the textbooks include information regarding FGM/FC. The results of this study show that US medical textbooks do not include information regarding FGM/FC, suggesting that most medical providers don’t have knowledge and training about FGM/FC. The inadequate information on FGM/FC in medical textbooks reflects a culturally biased lack of recognition of the number of girls and women affected in the US. This maintains an ongoing pattern of silence that reinforces gender inequality. Considering the inadequate information covered in US medical textbooks on FGM/FC, and the concordant lack of provider training to provide advice and care to affected girls and women, incorrect and missed diagnoses may lead to harm to victims of FGM/FC. Providers would be better equipped to care for women and girls if their medical training included information regarding FGM/FC.
文摘TBM钢拱架是用于隧道掘进开挖最重要的支护构件之一,其安装效率对隧道的稳定性及人员的安全性有着重要影响。为了减小TBM在隧道掘进过程中产生的振动造成钢拱架拼装系统安装效率低的不利影响,文中将约束理论(Theory of Constraints, TOC)和发明问题解决理论(Theory of Inventive Problem Solving, TRIZ)进行融合,应用于钢拱架拼装机构的减振设计。首先,采用TOC对钢拱架拼装机构的不合理约束进行系统分析;然后,运用TRIZ求解输出多种设计方案,结合工程实际对不同方案进行评估分析;最后,提出合理的问题解决方案。通过TOC/TRIZ理论的融合应用解决了钢拱架拼装机构的振动问题,为相关隧道工程装备的设计提供了参考。
文摘Buckling and postbuckling characteristics of laminated graphene-enhanced composite(GEC)truncated conical shells exposed to torsion under temperature conditions using finite element method(FEM)simulation are presented in this study.In the thickness direction,the GEC layers of the conical shell are ordered in a piece-wise arrangement of functionally graded(FG)distribution,with each layer containing a variable volume fraction for graphene reinforcement.To calculate the properties of temperaturedependent material of GEC layers,the extended Halpin-Tsai micromechanical framework is used.The FEM model is verified via comparing the current results obtained with the theoretical estimates for homogeneous,laminated cylindrical,and conical shells,the FEM model is validated.The computational results show that a piece-wise FG graphene volume fraction distribution can improve the torque of critical buckling and torsional postbuckling strength.Also,the geometric parameters have a critical impact on the stability of the conical shell.However,a temperature rise can reduce the crucial torsional buckling torque as well as the GEC laminated truncated conical shell’s postbuckling strength.
