高职高专地籍与房产测量课程教学改革思考

“就业导向、工学结合”已成为高等职业教育人才培养模式改革的重要切入点,这给作为主干专业课程的“地籍与房产测量”教学带来全新的课题.为了构建适应这种新形势的教学模式,分别从教材建设、教学内容、教学手段、实践教学和考试形式5个方面进行了探索.     

以太网供电技术及受电端电路设计

为解决具有以太网接口的小型功率设备供电不便的问题,在分别分析IEEE 802.3af标准中的以太网供电系统构成、以太网供电传输方式、以太网供电过程及其他电气特性的基础上,提出了一种通过以太网获取电源的解决方案,并给出了详细的电路设计原理图。该方案可同时支持以太网供电输入和其他辅助电源输入,并可以同时输出3.3 V和5 V这2种电压供系统使用。测试结果表明,该设计方案具有较低的成本和较高的效率,能够很好地解决小型功率设备供电不便的问题。     

四氢萘微观结构的量子化学研究

为了研究氢化芳烃的微观结构,进一步认识和理解氢化芳烃在催化裂化过程中的反应特性。以四氢萘为模型化合物,利用基于密度泛函理论的量子化学从头计算方法,对四氢萘的几何结构和电子结构进行了系统研究,得到了四氢萘不同位置C-H键和C-C键的键长、键级、键能以及电子云密度、前线轨道分布等微观结构信息。发现四氢萘结构具有轴对称特性,苯环上的C-C键和C-H键要远比环烷环的C-C键和C-H键稳定。由于受苯环的影响,会使得其环烷环上不同位置的C-C键的键长、键级和键能均具有明显差异,也导致环烷环上不同位置C-H键的键长、键级和键能有较明显的差异,具体表现为:对C-C键而言,与苯环相连的C-C键的键长较短,键级较高,键能也明显较高,而苯环β位C-C键的键能则明显较低;对C-H键而言,与苯环β位环烷碳原子上的C-H键相比,苯环α位环烷碳原子上的C-H键的键能明显较低。电子云分布计算结果能够较好地给出的这些C-C键和C-H键结构特征差异的原因。前线轨道计算结果表明,在催化裂化过程中,苯环α位环烷碳原子上的C-H键和β位C-C键较易受到催化剂酸性中心的进攻,是酸催化反应的位点。这些计算结果对于认识与理解氢化芳烃的反应特性具有一定的基础性理论意义。     

玻璃中离子注入的进展

玻璃中离子注入的进展王承遇，王波，陶瑛（大连轻工业学院玻璃及无机新材料研究所１１６００１）ＴｈｅＤｅｖｅｌｏｐｍｅｎｔｏｆＩｏｎ－ＩｍｐｌａｎｔｉｏｎｉｎＧ１ａｓｓｅｓ￥ＷａｎｇＣｈｅｎｇｙｕ；ＷａｎｇＢｏ；ＴａｏＹｉｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＧｌ...     

A Digitally Controlled Stimulator for Neurophysiological Applications

A stimulator circuit is presented which is capable of generating pulse train waveforms suitable for neurophysiological experiments are available, as well as special test conditions such as dishabituation. Digital and linear integrated circuits are used to provide precise control over the stimulus parameters.     

Preparation of BaTiO3-Based Nonreducible X7R Dielectric Materials Via Nanometer Powders Doping

Nonreducible X7R dielectric materials, which can be cofired with Ni electrode, were obtained by doping nanometer additives to BaTiO₃ powders synthesized by employing a sol-gel method. The crystallization process, structure and constituent of nanometer additives, as well as morphologies were studied via differential thermal and thermogravimetric analyses (DTA/TG), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of the calcining temperature of dopants on the dielectric properties were also discussed. The experiment results proved that higher-performance X7R dielectric materials could be obtained via nanometer doping compared with conventional doping. At room temperature, dielectric constant is more than 3000; dielectric loss lower than 1.0% and insulation resistance more than 10¹¹Ω ⋅cm.     

Machinability of Metal Matrix Composites Reinforced by 3-D Network Structure

Metal matrix composites reinforced by three-dimensional (3-D) continuous network structure reinforcement (3DCNRMMC) are difficult to machine due to serious tool wear and poor surface roughness caused by the brittle and hard reinforcement which interpenetrate into ductile matrix. In order to achieve the approach of low cost of 3DCNRMMC, the machinability of it needs to be understood. The influences of three cutting parameters and volume fraction of reinforcement on cutting force were analyzed in detail. The results indicate that: (1) Due to the brittle phase(s) introduced into ductile matrix of composites, there is a large fluctuation of cutting force causing deterioration of machinability. The fluctuation ranges of cutting forces, initially increase rapidly with the increase of volume fraction of reinforcement and then decrease finally, are largest at the range of the volume fraction of 55–65%; (2) The influence of cutting parameters on cutting force is obvious. With the increases of cutting speed, cutting force decreases gradually unless cutting speed exceeds the value of 209 m/min. Cutting forces increase with increasing feed rate and depth of cut; (3) Owing to the large fluctuation of cutting force, there were some cratered surfaces caused by Si₃N₄ reinforcement pulling-out and flaking-off. Some brittle phase protruding from the machined surface caused the deterioration of machined surface.     

超细片状铝粉和铝银浆的制备

超细鳞片状铝粉和铝银浆由于其特殊的二维平面结构，具有良好的遮盖力、显著的屏蔽效应、光学反射能力；超细鳞片状铝粉和铝银浆颜料的制备方法很多，本文采用机械化学法制备超细鳞片状铝粉和铝银浆。     

Integrated plasma-aided nanofabrication facility: Operation, parameters, and assembly of quantum structures and functional nanomaterials

The development, operation, and applications of two configurations of an integrated plasma-aided nanofabrication facility (IPANF) comprising low-frequency inductively coupled plasma-assisted, low-pressure, multiple-target RF magnetron sputtering plasma source, are reported. The two configurations of the plasma source have different arrangements of the RF inductive coil: a conventional external flat spiral “pancake” coil and an in-house developed internal antenna comprising two orthogonal RF current sheets. The internal antenna configuration generates a “unidirectional” RF current that deeply penetrates into the plasma bulk and results in an excellent uniformity of the plasma over large areas and volumes. The IPANF has been employed for various applications, including low-temperature plasma-enhanced chemical vapor deposition of vertically aligned single-crystalline carbon nanotips, growth of ultra-high aspect ratio semiconductor nanowires, assembly of optoelectronically important Si, SiC, and Al_1-xIn_xN quantum dots, and plasma-based synthesis of bioactive hydroxyapatite for orthopedic implants.