平面桁架构建的定日镜面形支撑结构优化及实验

针对反射面成型的复杂影响因素，提出平面桁架构建的定日镜面形支撑结构优化技术路线. 利用模拟仿真、数值计算和优化算法等方法，解析20 m²定日镜面形定义技术路线的4个组成环节：面形规格及宽高比、上弦杆的截面矩、平面桁架组间距的最优值、机加工中工艺控制要点的量化. 试制小型定日镜进行实验，分析光斑形状和能流密度分布特性，并与理想球面形光斑比较，两者的拟合优度大于0.98. 实验结果表明，当反射镜宽高比取1.2，上弦杆截面矩取40 000 mm⁴，桁架组间距取950 mm，上弦杆和斜杆的开孔公差小于0.9 mm时，反射面形的质量提升. 研究从原理和实践上证明了该优化技术路线的可行性.     

Evaluation of behavior of the secondary columns in semi-supported steel shear walls

Semi-supported steel shear walls (SSSW), whose steel plate is connected to secondary columns rather than main columns of the frame, have been considered as an alternative steel shear walls to the traditional type. Many investigations have been made for proportionate designing of components of SSSW system. One of the important issues in this regard is the out of plane buckling of the secondary columns. In this paper, the plastic theory of structures is utilized to find out the axial force distribution, along the compressive column. Then, using energy method, for an assumed shear wall with specific geometry and material and a given shear force, the maximum overturning moment that makes the compressive secondary column buckles, can be determined. Repeating this method, for various shear forces, makes it possible to draw some interaction curves between overturning moments and shear forces. These curves can be used to analyze and design of semi-supported steel shear walls.     

塑料牙刷柄的傅立叶变换红外光谱分析

本文采用傅立叶变换光谱法对13种不同品牌的白色牙刷柄塑料进行了红外光谱分析,实验结果表明,依据红外光谱数据的异同,能够对不同品牌的牙刷柄样品进行鉴别。     

Properties of starch–cellulose fiber films produced by tape casting coupled with infrared radiation

Tape casting is a suitable process for large-scale production of biodegradable films. This study presents a comparison of three drying procedures of starch–cellulose films: i) conduction drying, ii) infrared drying (42.3?W?m^?2, higher infrared heating power damaged the films), and iii) conduction-infrared drying. All the drying procedures were performed at approximately 60°C. Drying times from the second and third methods were close to 1?h, half the time observed for conduction drying. Films from the second and third methods showed similar hygroscopicity (0.15?g.?g^?1, RH 43%), tensile strength (31.3?MPa, RH 58%), and glass transition temperature (?12.13°C, RH 43%).     

Analysis and comparison of different methods used to extract isoclinic and isochromatic parameters. Application to the determination of the residual stresses inside crystal silicon wafers

The present work focuses on an experimental analysis of different photoelastic extraction methods. An adapted test rig designed in order to evaluate several extraction methods, which come from the literature and 2 new proposed methods. Their comparisons point out dissimilar behaviours between them in an experimental environment. However, some specific cases require the use of most appropriate techniques to minimise the defects influence. Therefore, a specific application of the photoelasticity is presented to illustrate the meaning of the technique used. It mainly focuses on the determination of the residual stresses and their orientation inside photovoltaic crystal silicon wafers.     

Efficient Photomodulation of Visible Eu(III) and Invisible Yb(III) Luminescences using DTE Photochromic Ligands for Optical Encryption

This work describes a class of complex combining three dithienylethene units and a lanthanide ion used as an optical system displaying a double encryption method: i) a colorful code, drawn and erased under UV and visible irradiations respectively, due to coloration and discoloration of the photochromic entities, and ii) a concomitant gradual disappearance and progressive restoration of the associated lanthanide ion luminescence triggered with the same stimuli. The innovation of the system stems from the emission color tunability, i.e., with either a lanthanide ion emitting only in the visible range (Eu³⁺) or with another lanthanide ion emitting only in the near infrared (NIR) range (Yb³⁺), therefore observable, or not, to the naked eye. This system is the very first one to achieve efficient repeatable modulation of pure NIR luminescence on photochemical command. Furthermore, it is proven to be highly efficient when embedded in a PDMS polymer opening real opportunities for practical applications as anti‐counterfeiting.     

TG-FTIR and Py-GC/MS study of the pyrolysis mechanism and composition of volatiles from flash pyrolysis of PVC

To facilitate the reuse and recycling of polyvinyl chloride (PVC) to achieve sustainable development and new industrialization, the composition and mechanism of formation of volatiles during the flash pyrolysis of PVC were studied by thermogravimetry-Fourier transform infrared (TG-FTIR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). TG and derivative thermogravimetry (DTG) analyses indicated two main degradation stages during flash pyrolysis of PVC, namely dehydrochlorination of PVC and decomposition of dechlorinated-PVC. Simultaneously, the FTIR results revealed that the main functional groups in the pyrolysis process were H–Cl, -C-Cl, C–H, CH, and aromatic groups. The relative content of main volatiles was determined by Py-GC/MS, and decreased in the following order: aromatics > alkenes > hydrogen chloride (HCl) > chlorinated hydrocarbons. Specifically, the relative content of aromatics was as high as 76.790–81.809%, while that of HCl was in the range of 3.016–3.096%. The carbon number distribution and the relative content of main products obtained from the flash pyrolysis of PVC at different final temperatures were also analysed. According to the experimental results, the mechanism of formation of the main volatiles based on free-radical reactions was deduced in detail. Therefore, this study provides further details for deepening the understanding of the PVC pyrolysis process.     

细化变质处理对铸造A356铝合金组织性能及共晶硅生长机制的影响

研究了采用新型Al-5Ti-1B-1RE中间合金和Al-10Sr中间合金对A356铝合金进行单一或复合细化变质处理后的组织、力学性能和共晶硅生长机制的影响。结果表明：单一细化变质处理中Al-5Ti-1B-1RE中间合金对A356铝合金中α-Al相有明显的细化作用,合金的强度和维氏硬度显著提高；Al-10Sr 中间合金对共晶硅有强的变质作用,合金的伸长率明显提高；而经复合细化变质处理后α-Al相形状和尺寸变得更均匀细小,晶界更清晰,共晶硅相几乎都转变成更弥散、更细小的纤维状,片层状共晶硅也几乎完全消失,共晶硅长度由铸态40-60 μm降低到1-2 μm之间,达到完全变质效果,其力学性能显著高于铸态、单一细化变质剂处理的A356铝合金。未细化变质的A356铝合金中的共晶Si的生长方式为典型的小平面台阶生长,复合细化变质处理的共晶硅以孪晶凹槽机制生长为主,小平面生长特征逐渐减弱直至消失。