A two-pronged approach for springback variability assessment using sparse polynomial chaos expansion and multi-level simulations

In this study, we show that stochastic analysis of metal forming process requires both a high precision and low cost numerical models in order to take into account very small perturbations on inputs (physical as well as process parameters) and to allow for numerous repeated analysis in a reasonable time. To this end, an original semi-analytical model dedicated to plain strain deep drawing based on a Bending-Under-Tension numerical model (B-U-T model) is used to accurately predict the influence of small random perturbations around a nominal solution estimated with a full scale Finite Element Model (FEM). We introduce a custom sparse variant of the Polynomial Chaos Expansion (PCE) to model the propagation of uncertainties through this model at low computational cost. Next, we apply this methodology to the deep drawing process of U-shaped metal sheet considering up to 8 random variables.     

ZZ9900/29.5/50型支架护帮装置限压阀板的改进

对ZZ9900/29.5/50型支撑掩护式大采高液压支架护帮装置限压控制系统限压阀板存在的缺陷进行了分析、改进.     

Motorcyclists’ speed and “looked-but-failed-to-see” accidents

Previous research on motorcycle crashes has shown the frequency and severity of accidents in which a non-priority road user failed to give way to an approaching motorcyclist without seeing him/her, even though the road user had looked in the approaching motorcycle's direction and the motorcycle was visible. These accidents are usually called “looked-but-failed-to-see” (LBFS) accidents. This article deals with the effects that the motorcyclist's speed has in these accidents. It is based on the in-depth study and precise kinematic reconstruction of 44 accident cases involving a motorcyclist and another road user, all occurring in intersections. The results show that, in urban environments, the initial speeds of motorcyclists involved in “looked-but-failed-to-see” accidents are significantly higher than in other accidents at intersections. In rural environments, the difference in speed between LBFS accidents and other accidents is not significant, but further investigations would be necessary to draw any conclusions. These results suggest that speed management, through road design or by other means, could contribute to preventing “looked-but-failed-to-see” motorcycle accidents, at least in urban environments.     

A near-infrared dye for dye-sensitized solar cell: Catecholate-functionalized zinc phthalocyanine

The design and synthesis of an asymmetrical zinc phthalocyanine sensitizer modified with a catechol anchoring group is reported. The performance of this sensitizer was evaluated in a dye-sensitized solar cell. A strong interaction between the catechol dye and TiO₂ (with the formation of a five-membered charge-transfer complex) was evidenced by a strong shift in the Q-band of the ZnPc-Cat from 680 nm in solution to 750 nm on TiO₂, along with an appreciable absorption tail extending to ∼1000 nm. The fabricated solar cell containing the phthalocyanine sensitizer showed relatively high light-to-electron conversion efficiency (η = 0.92%), considering that few catechol dyes exceed η = 0.7% in dye-sensitized solar cells. Values of I_sc = 2.53 mA cm⁻² and V_oc = 540 mV were obtained, referring to a standard N719 cell (η = 6.46%). A comparison of zinc phthalocyanine sensitizers bearing different anchoring groups affirmed the superiority of carboxylate groups relative to those bearing catechol groups in terms of cell performance.     

农药作为海洋防污剂的应用

纵观海洋防污剂发展史，我们可以发现它和农药之间有着不解之缘，也可以说农药的发展推动了防污剂的发展。文章对曾经用过、正在使用、有可能应用为海洋防污剂的农药品种逐一介绍。     

X-RAY镀层测厚仪检测及校正方法浅析

基于X-RAY荧光光谱方法的基础理论,简单分析了能量散射X-RAY荧光光谱分析法的工作原理,通过对准直器尺寸、测量时间、应用程式、基材等参数的选择,分析了X-RAY镀层测厚仪检测及校正的方法。结果表明,检测校正后的X-RAY镀层测厚仪,测量结果的相对误差、相对标准差小,且该方法对企业生产具有指导意义。     

建筑渗漏处理技术的研究

工程中的渗漏问题会大大影响房屋的使用,怎样解决房建工程中的渗漏问题,已经成为亟待解决的工作.以上海艾格美国际公寓中存在的渗漏现象为例,对其原因展开了分析,并有针对性地提出了解决处理技术,这些技术为艾格美国际公寓提供了更好的居住环境,同样为相关工程提供了解决此类问题的思路.     

野外环境下陀螺全站仪定向精度与稳定性的测试与分析

基于高精度的野外地表控制网,针对不同的时间、地点和温度变化环境以及振动变化环境等实际的野外观测条件,对HGG05型陀螺全站仪的稳定性和指北定向精度进行测试与研究,通过多个周期测试数据的分析,总结出了一套方法可行、成果可靠的陀螺全站仪测试方法与数据处理程序。