基于激光三角法的传感器设计

介绍了一种基于激光三角法原理的光学传感器的设计.该传感器由CCD摄像机和激光器组成,主要用于测量路面的平整度.实验结果得出的最初原形显示此传感器在竖直方向的测量范围可达到1 100 mm,横向测量范围达1 300 mm.横向平均绝对误差约为0.05 mm;纵向平均绝对误差约为0.08mm.这种传感器具有测量范围大,精度高,且能工作于条件苛刻的环境等优点.     

Synthesis of (BaxSr1−x)(Zn1/3Nb2/3)O3 ceramics by reaction-sintering process and microstructure

(Ba_xSr_1−x)(Zn_1/3Nb_2/3)O₃ complex perovskite ceramics produced by reaction-sintering process were investigated. Secondary phases ZnNb₂O₆ and (Cu₂Zn)Nb₂O₈ were found at the perovskite matrix grain boundaries. 98.5–99.8% of the theoretical density was obtained. In (Ba_0.5Sr_0.5)(Zn_1/3Nb_2/3)O₃ and (Ba_0.7Sr_0.3)(Zn_1/3Nb_2/3)O₃, the amount and volume of second phases decreased clearly at 1500 °C.     

Alignment of ZnO nanowires on Al,Ti, Pt electrodes

Growing and alignment of ZnO and Si nanowires on the selective location on several kinds of conducting electrodes have been studied. Aluminum, titanium, and platinum which are typical electrode materials in the current state of the art were considered as electrode materials. For the patterned growth of the ZnO and Si nanowires on the selective area of the conducting Al, Ti, and Pt electrodes, Au catalytic layers were deposited on the selective area of the electrodes and the optimum processing conditions by which the nanowires could be grown only where the patterned catalytic layer is present were examined.     

新型汽车用高强度钢的应用现状与发展趋势

对先进的高强度钢及其在汽车工业中的应用进行了评述,详细介绍了几种高强度钢,如烘烤硬化钢、双相钢、相变诱发塑性钢等的原理、成分、性能特点以及目前的应用现状与开发进展状况.简述了高强度钢板在成形中所遇到的延伸凸缘性和弯曲成形性有所降低、回弹和弯曲开裂现象增多等问题,指出应把高强度钢板研究与对应的成形应用技术研究结合起来.还简述了国内外在高强度钢板上的研究方向,即在进一步提高强度、降低车重的同时,综合考虑安全、成形等因素,通过更多的新的强化机制来提高强韧性.     

The Microstructure and Properties of Diffusion Layer of Spray Aluminum

After diffusion processing of thermal spraying , aluminum on 20^# steel is discussed in this article. Variations of microstructure, composition as well as mierohardness and corrosion resistatwe of diffusion layer of spray aluminum were explored by means of X-ray diffraction, scanning electron microscopy （SEM） and electron probe microanlysis （ EPMA ） . The result shows that the diffusion layer of spray aluminum consists of η phase （ Fe2Al5 ）, ξ phuse （ FeAl2 ）, β2 phase （ FeA1 ）,β1 plmse （ Fe3Al ） and α pluse from surface to substrate. There are balanced transitions between phases. The layer has extra high hardness and corrosion resistance.     

Efficient field emission from tetrapod-like zinc oxide nanoneedles

Tetrapod-like zinc oxide (ZnO) nanoneedles were fabricated using a simple and economical method of rapid heating high purity zinc powders at 900 °C. No catalyst and vacuum were employed in the experiment. Field-emission measurements showed that the turn-on field of the synthesized tetrapod-like ZnO nanoneedles was as low as 1.8 V/μm at the emission current density of 1.0 μA/cm² and the emission current density reached 1.0 mA/cm² under an applied field of about 3.9 V/μm. The low turn-on field, high emission current density, and good electron emission stability make the ZnO nanoneedles one of the promising candidates for field-emission displays.     

Nanocomposite films of V<Subscript>2</Subscript>O<Subscript>5</Subscript>−MoO<Subscript>3</Subscript> xerogel with poly ethylene oxide intercalation

Poly ethylene oxide (PEO)_x−V₂O₅−V₂O₅−MoO₃ (x=0, 0.5, 1) films were prepared by the sol-gel method. The synthesis and structure of the films were investigated by XRD, TG-DTA, FTIR, etc. The results show that V₂O₅−MoO₃ xerogel has a layered structure and its interlayer space increased from 1.3181 nm at x=0 to 1. 7898 nm at x=1 after the nanocomposite films were dried, and PEO in the interlayer changes the interface structure by forming hydrogen bonds with V=0 bands. CV measurement indicates that the intercalation of PEO improves insertion/extration properties of Li⁺ ions in the interlayer. ZHENG Jin-xia: Born in 1976 Funded by the National Natural Science Foundation of China (No. 50172036) and Natural Science Foundation of Hubei Province(No. 2001ABB083)     

Effects of Solid-State Reaction Synthesis Processing Parameters on Thermoelectric Properties of MgaSi

The Mg2 Si-matrix thermoelectric material was stnthesized by low temperature solid-state renc-tion.This paper studies the effects of holding time and reaction temperatare on the particle size and the properties of the material, and also studies effects of doping elemental Sb, Te and their doping seqence on the properties of the materiol. The result shows that excessirely high temperature and elongated holding time of solid-state reaction are harmful, there is a range of partiele size to ensure optimum properties and the doping sequence of Sb or Te without influencing the properties.     

Experimental and finite element studies on hot sizing process for L-shaped composite beams

This work aims at developing a hot sizing process on composite materials to correct the profiles of composite structures during manufacture. Hot sizing experiments were carried out at 150 °C with different sizing loads and hot sizing periods for L-shaped composite beams made of carbon fiber plain-weave fabric and epoxy resin. To predict the springback in hot sizing process, a corresponding finite element simulation method was developed using stress relaxation equations determined at the same temperature. Excellent agreements between the predicted and observed results were obtained. The effects of the component thickness and 45° ply percentage on the springback rate were investigated by simulation. Springback rate in hot sizing process on composite materials ranges from 60% to 95%. In conclusion hot sizing process is proved to be a valid method for compensation for the process-induced deformation (PID) of L-shaped composite beams.     

The effects of PVP surfactant in the direct and indirect hydrothermal synthesis processes of ceria nanostructures

CeO₂ nanostructures with completely different morphologies were successfully prepared using the same cerium source and mineralizer through the direct and indirect hydrothermal methods with different introducing strategies of PVP surfactant. The CeO₂ nanostructures tend to form the morphologies of nano-flowers and nano-cubes through the indirect and direct hydrothermal methods, respectively. X-ray diffraction (XRD) analyses revealed that both as-prepared nanostructures are composed of CeO₂ with a standard fluorite structure. The different synthesis mechanisms and corresponding chemical evolutions of the as-prepared CeO₂ nanostructures are discussed based on the different introducing strategies of PVP surfactant in the direct and indirect hydrothermal processes. Investigation of the UV-shielding ability of both CeO₂ nanostructures suggested that the UV absorbance of the nano-flowers is much higher than that of the nano-cubes.