非晶粉末爆炸固结材料的磁性能

本文研究了非晶粉末爆炸固结材料的磁性能.结果表明爆炸固结态样品磁性能表现为Br/Bs、初始磁导率偏低,不易磁化到饱和,矫顽力偏高,经低温短时保温退火处理后样品磁性能显著提高,但过长的保温时间、较高的退火温度则会导致样品晶化而造成磁后退,400℃×20min水淬为最佳退火工艺条件.     

机械活化Mo-Cu粉末的烧结

研究了Mo-Cu粉末,经机械活化处理后的组织、形态与液相烧结性能、合金组织的关系,实验结果表明:一定时间活化处理,Mo-Cu粉末形成机械合金化初期的层状组织,其压坯可在较低温度液相烧结,合金相对密度大于99%,组织细小、均匀。     

同步发电机微机励磁调节器的设计与实现

介绍了基于DSP芯片TMS320LF2407A的同步发电机微机励磁调节器的设计原理与实现过程。它利用DSP芯片可快速执行傅里叶算法的优点，通过采用同步采样A／D转换器芯片ADS7864实行交流同步采样的方法，对同步发电机出口端的定子电压、电流进行准确测量；通过PID和最优控制的方法，得到精确的脉宽调制控制信号输出；并且利用DSP芯片上的串行通信接口SCI和CAN控制器接口，实现多机之间和与上位机之间的调试及监控通信。     

Fe—P与Fe—P—Ce合金中的晶界磷偏聚及其对脆性的影响

用XPS,AES及系列冲击试验等方法对含磷0.032—0.22wt％的Fe-P和Fe-P-Ce合金中晶界偏聚磷的存在状态、偏聚特点及对脆性的影响进行了研究。结果表明,晶界上磷的存在状态与其偏聚量有关。当偏聚量较低时,为固溶态,且Ce的影响很小,而当偏聚量较高时,其存在状态改变,且Ce的影响显著。     

矿山生产对井下资源的影响及水文地质灾害防治措施

随着时代的不断发展,我国大部分矿山的生产建设已经取得了非常大的进步。但由于近年来水文地质灾害频频发生,严重影响了整个矿山生产的安全以及质量。本文就矿上生产在当前阶段对井下资源的影响以及水文地质灾害的防范进行一定分析和探究,以供参考。     

Characterization of self-assembled metallodendrimers in solution, in the gas phase, and at air/solid interfaces

It is found that 4,4'-bipyridines functionalized in their 3,3'-positions with Fréchet dendrons of 0th to 3rd generation self-assemble with (dppp)M(II) triflates (dppp: bis-(diphenylphosphino)propane; M = Pd, Pt) into metallo-supramolecular squares. They bear a nanometer-sized cavity inside an unpolar dendritic shell. A total of eight amide groups decorate the rims of the cavity connecting the dendrons to the square. Evidence for their formation up to the third generation comes from ESI-FTICR mass spectrometry and NMR experiments. Based on these results, the presence of significant amounts of other polygons or open-chain oligomers can be excluded. Exchange processes have been studied by variable-temperature NMR spectroscopy and by following the ligand exchanges between different squares by mass spectrometry. The ligand exchange is much slower for the Pt(II) squares as compared to their Pd(II) analogs. Visualization of films of these dendrimers using atomic force microscopy (AFM) provides information on their molecular dimensions. After deposition of a square monolayer on the surface, a slow reorganization within this layer is observed which leads to the formation of "tower-like" aggregates and multi-layer formation. The interplay of interactions between the dendrimers and the surface and interactions between different dendrimers are invoked to rationalize the observations.     

Successful implementations of MES in Korean manufacturing SMEs: an empirical study

This study explores the factors that affect the successful implementation of the Manufacturing Execution Systems (MES) in small and medium manufacturing enterprises (SMMEs). To this end, a survey was carried out. Responses from 163 SMMEs were analysed. The results found that all hypothesised variables including top management support, sufficiency of investment, capacity of the system developer, and user participation were critical factors for successful MES implementation in SMMEs. This study is the first empirical study on the successful implementation of MES in SMMEs in the Asia/Pacific region.     

Preparation and characteristics of nano-B4C/PVA particles and ultra high molecular weight polyethylene composites

In-situ mechanical process for preparation of the polyvinyl alcohol (PVA) coated nano-B₄C powder was investigated by using a high-energy ball mill. The produced PVA coat on the surface of nano-B₄C particles was observed by x-ray diffraction (XRD) and confirmed by TEM images. The average particle size of the produced nano-B₄C/PVA particles was in the range of several tens to hundreds of nanometers depending on the milling conditions. The polymer composites were fabricated by hot pressing ultra high molecular weight polyethylene (UHMWPE) powder mixed with nano-B₄C/PAV and micro-B₄C powders, respectively. Nano-B₄C/PVA dispersed UHMWPE shows slightly lower crystallinity and stiffness than micro-B₄C dispersed UHMWPE based on differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) evaluations.     

膨胀水箱有效容积计算的探讨

膨胀水箱有效容积的计算,现有几种计算表达公式,由于公式中水温波动值的取值不一样,其计算结果也不尽相同。现就一些公式中水温波动值的取值问题谈谈看法,并提出取值的范围,这样可使膨胀水箱的有效容积缩小,既可减少工程造价,同时又有利于建筑物的抗震。     

基于双重零水印的数据库版权保护

数据库零水印具有二义性,可能引起数据库的版权纠纷。为此,提出一种数据库版权图像零水印算法。以零宽度不可见字符作为水印符号,将版权图像嵌入宿主数据库,构造一重数据库零水印,同时使用字符型数据Unicode编码提取二重数据库零水印。实验结果表明,该算法可以提高数据库版权保护能力。