人工颅骨用复合材料中微量甲基丙烯酸甲酯的气相色谱法测定

采用氢气焰离子化检测器(FID),以正丁醇为外标物,PEG-20M为固定相,甲醇作为溶剂,气相色谱法测定复合材料人工颅骨中微量MMA的含量。其相对标准偏差<0.022,平均回收率(n=4)为98.0％～99.1％。此方法操作简便,用于实际样品分析可得到满意的结果。     

双膦胺镍-甲基铝氧烷体系催化苯乙烯聚合

研究了具有新型结构的双膦胺镍配合物N,N-双(二苯膦基)-对甲氧基苯胺二氯化镍-甲基铝氧烷(PNP-N i-MAO)催化体系对苯乙烯聚合的催化性能,考察了聚合温度、n(A l)∶n(PNP-N i)、PNP-N i的浓度和苯乙烯的浓度对催化活性、苯乙烯转化率、聚苯乙烯相对分子质量及其分布的影响,并用核磁共振和凝胶色谱对聚苯乙烯的结构进行了表征。实验结果表明,在聚合温度25℃、聚合时间1h、n(A l)∶n(PNP-N i)=300、c(苯乙烯)=2.3m ol/L、c(PNP-N i)=0.4mm ol/L、甲苯为溶剂的适宜条件下,苯乙烯的转化率可达95%以上,催化活性达到5×105g/(m ol.h)左右。核磁共振和凝胶色谱表征结果显示,所得聚苯乙烯为无规结构,重均相对分子质量约为1×104,相对分子质量分布Mw/Mn约为2。     

新场气田致密低渗透气藏重复压裂工艺技术

新场气田蓬莱镇组气藏由于储层致密、渗流条件差，单井自然产能低，所以多数气井必须进行压裂改造才能投产，但由于受储层致密和其它多种因素的影响，压裂增产有效期较短，针对这种情况，进行了气井重复压裂工艺技术的理论计算和现场应用研究，初步形成了一套包括储层评估、重复压裂潜力井优选、重复压裂造缝机理研究、优化重复压裂施工及配套工艺和压后评估的气井重复压裂技术。现场试验表明，对具有潜力的压裂失效气井采取重复压裂措施，能取得较好的增产效果。气井重复压裂技术的形成和推广，将有效提高川西地区各气藏的开发水平，同时也为类似致密碎屑岩气藏的开发提供有益的指导和借鉴。     

真空铸造高强度C/Mg复合材料

本文介绍用真空铸造法制造抗拉强度超过1000MPa的高强度C/Mg复合材料。将T300纤维经C-Si-O梯度涂层处理后单向排布于型腔内,在真空下注入ZM-5合金液,凝固后即得C/Mg复合材料零件或试样。试样的抗拉强度在纤维体积分数为0.35时达1050MPa。本文讨论C-Si-O梯度涂层对获得高强度复合材料的作用。     

放置过滤器浇注系统的设计

综述了常用的网型、芯型、泡沫陶瓷过滤器的研究和应用情况。指出应根据过滤器类型，确定其在浇注系统中的安放位置并相应改变该处的结构和截面积，以便在使用过滤器净化金属的同时，保证充型速度不变。     

High-frequency small signal AC and noise modeling of MOSFETs for RFIC design

High-frequency (HF) AC and noise modeling of MOSFETs for radio frequency (RF) integrated circuit (IC) design is discussed. A subcircuit RF model incorporating the HF effects of parasitics is presented. This model is compared with the measured data for both y parameter and f_T characteristics. Good model accuracy is achieved against measurements for a 0.25 μm RF CMOS technology. The HF noise predictivity of the model is also examined with measured data. Furthermore, a methodology to extract the channel thermal noise of MOSFETs from HF noise measurements is presented. By using the extracted channel thermal noise, any thermal noise models can be verified directly. Several noise models including the RF model discussed in this paper have been examined, and the results show that the RF model can predict the channel thermal noise better than the other models     

On loop transformations for generalized cycle shrinking

This paper describes several loop transformation techniques for extracting parallelism from nested loop structures. Nested loops can then be scheduled to run in parallel so that execution time is minimized. One technique is called selective cycle shrinking, and the other is called true dependence cycle shrinking. It is shown how selective shrinking is related to linear scheduling of nested loops and how true dependence shrinking is related to conflict-free mappings of higher dimensional algorithms into lower dimensional processor arrays. Methods are proposed in this paper to find the selective and true dependence shrinkings with minimum total execution time by applying the techniques of finding optimal linear schedules and optimal and conflict-free mappings proposed by W. Shang and A.B. Fortes     

全IP移动通信网网络层移动性管理

首先介绍了全IP移动通信网网络层移动性管理的概念、框架和最经典的移动IP（Mobile IP）协议，然后讨论了基于Mobile IP的四种主要扩展方案：蜂窝IP、切换敏感无线接入Internet结构（HAWAII)、电信增强移动IP（TeleMIP）和边缘移动性体系结构（EMA）方案，最后结合第三代移动通信发展的状况得出了一些结论。     

A versatile data acquisition system for time resolved X-ray scattering using gas proportional detectors with delay line readout

A data acquisition system for time resolved X-ray scattering experiments using linear, quadrant or area gas proportional detectors with delay line readout based on commercially available hardware (National Instruments) is described. The system can easily be configured for recording data from point detectors (e.g. photomultipliers and photodiodes) and/or ancillary data only. Applications involving measurements with two different types of time to digital converters illustrate the features and performances of the system.     

冲击响应谱在惯导减振防冲设计中的应用

根据冲击原理,研究惯导减振系统在半正弦冲击激励下的响应特性,绘制了惯导系统在半正弦冲击激励下的冲击响应谱图。根据冲击响应谱图,可为惯导系统防冲设计提供正确、有效的理论依据,同时,为使减振器同时具备减振、防冲两种性能,冲击响应谱对于减振器关键参数选择、减振系统优化也具有重要应用价值。最后文章依据该研究结论,对某惯导系统进行了实际设计计算。