AlN-BN复合陶瓷制备工艺研究进展

本文详细介绍了AlN-BN复合陶瓷材料制备工艺的研究状况,包括AlN、BN粉末的合成制备和AlN-BN复合材料的制备工艺,评述了各种方法和工艺的优缺点。最后指出了粉末制备工艺中的自蔓延高温合成法、电弧等离子体法和烧结工艺中的反应烧结、放电等离子烧结是很有价值的研究方向。     

浅析计算机网络信息安全问题及对策

随着IT应用在生活中的日益普及,互联网已经覆盖了175个国家和地区的数亿台计算机,用户数量超过lO亿计算机技术广泛应用于各行各业,向着深度和广度不断地发展,构成了各自的网络,为资源共享、信息交换和分布处理提供了良好的环境,企业上网、政府上网、学校用网以及网上购物等计算机的应用表现了一个网络化的社会已经呈现在我们的面前、因此,在增加网络实用性的同时,系统的脆弱性不可避免的显露了出来,使计算机网络面临严重的安全问题。!     

江苏省地震前方指挥车应急数据信息通信方式的实现

前方指挥车是在有地震灾害事件发生时,能够立即响应,并快速到达地震震中所在地,立即开展现场信息汇集与共享、地震灾情动态评估和修正、辅助决策建议及时生成、现场资源调度和管理,实现前方指挥部与现场工作人员、国家指挥部、区域指挥部的不同应用系统之间的数据信息的共享和传递.本文主要介绍前方指挥车两种不同应急通信方式,并讨论各自的优缺点.     

AS／MBS／NBR共混体系研究

本文研究了ＡＳ／ＭＢＳ／ＮＢＲ共混体系的性能与组成比，形态结构的关系；考察了ＭＢＳ及ＮＢＲ牌号，成型加工温度对共混物性能的影响。结果表明，对于ＡＳ树脂，ＭＢＳ与ＮＢＲ之间存在强烈的同增韧效应，当总弹性体含量为３０％时，ＭＢＳ与ＮＢＲ配比在１／１１－１／１如此宽的范围内，共混物均具有优异的冲击韧性，且变化不大，其数值在６８７－７１３Ｊ／ｍ之间；共混物同时具有良好的综合性能。     

腐植酸化肥增效作用的最新例证--略谈两种新型HA肥料的试验研究与质量指标

经过5年5地对8种作物进行的田间试验，结果表明包裹型腐植酸长效尿素(UHA)和缓释腐植酸有机复合肥(SRCF)两个腐植酸类肥料新产品均对化肥有增效作用。     

Relationships Between the Crystal Structures and the Multiple Melting Behaviors of Poly(ethylene 2,6‐naphthalate)

Summary: Poly(ethylene 2,6‐naphthalate) (PEN) can crystallize either from the glassy state or from the melt state. When crystallized from the glassy state, the sample was quenched from the melt in liquid nitrogen and then annealed at certain crystallization temperatures. When crystallized from the melt state, the sample was cooled to a preset temperature from the melt and then annealed for a certain time. The crystal modifications, morphologies and melting behaviors of PEN were investigated by means of wide‐angle X‐ray diffraction (WAXD), polarized optical microscopy (POM), small‐angle light scattering (SALS) and differential scanning calorimetry (DSC). The results show that an α crystal modification of PEN was obtained when PEN crystallized from the glassy state, whilst a β crystal modification was obtained when PEN crystallized from the melt state at a higher temperature. An hedritic morphology of PEN crystal was obtained with only one melting peak observed in DSC curves when PEN was crystallized at a higher temperature from either the glassy state or the melt state. The α crystal modification could also be obtained when PEN was crystallized at a lower temperature from the melt. Spherulitic or banded spherulitic morphologies of PEN crystals, exhibiting multiple melting peaks in DSC curves, were observed when PEN was crystallized at a lower temperature. The multiple melting behaviors of PEN crystals may be associated with spherulitic structures composed of lamellae of varying thickness.

WAXD patterns of PEN isothermally crystallized from different states.     

The tribological behavior of micrometer and nanometer TiO2 particle‐filled poly(phthalazine ether sulfone ketone) composites

Micrometer and nanometer TiO₂ particle‐filled poly(phthalazine ether sulfone ketone) (PPESK) composites with various filler volume fractions from 0.5 to 7.5 vol % were prepared by heating compression molding. The friction and wear behaviors of the PPESK composites were evaluated using the block‐on‐ring test rig by sliding PPESK‐based composite blocks against a mild carbon steel ring under dry friction conditions. The wear debris and the worn surfaces of the PPESK composites filled with micrometer and nanometer TiO₂ particles were investigated by using a scanning electron microscope (SEM), while the structures of PPESK composites and wear debris were analyzed with IR spectra. Experimental results show that antiwear properties of the PPESK composites can be improved greatly by filling nanometer TiO₂ particles, and the friction coefficient decreases when the filler volume fraction is below 2.5%, but when the filler volume fraction is above 2.5% the friction coefficient increases gradually with increasing filler volume fraction. In the case of micrometer TiO₂ filler, wear rates increase with increasing filler volume fractions under identical test conditions, and the friction coefficients are less sensitive to the filler volume fraction. It was also found that the wear mechanism of micrometer TiO₂ particle‐filled PPESK is mainly severe adhesion and abrasive wear, while that of nanometer TiO₂ particle‐filled PPESK is mainly slight abrasive wear. In the former case, there are no transfer film formed on the surface of the counterpart steel, and wear debris are in the form of long and large ribbon. While in the latter case, the wear debris was granule and their size was about 10 μm. In case of 1 vol % nanometer TiO₂ particle‐filled PPESK composites, the transfer film was fairly thinner and smoother, and the transfer film provided better coverage on the surface of steel ring, while that of 7.5 vol % was thicker and discrete. These account for the different friction and wear behavior of micrometer and nanometer TiO₂ particle‐filled PPESK composite. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 906–914, 2004     

一种公交网络最优路径新算法*

从出行者的实际情况出发,提出步行愿望系数,综合考虑最小换乘次数、最短时间以及最小费用等因素,提出了一种公交网络最优路径新算法,应用于广州市大学城内公交线路查询,实现相应的仿真系统。     

改进SSR算法在人脸识别中的应用

为提高人脸检测中人脸验证的速度,在平方积分图像和图像窗口的灰度均值及方差快速计算基础上,对传统的SSR算法中人脸验证算法部分进行了改进。应用改进的算法,结合窗口灰度标准化的计算和平均人脸模板的取得,引入相关系数和平均偏差,加快了求解速度,克服了由于噪声点的存在对真实的候选脸图像漏检的情况。人脸检测实验证明应用改进的模板匹配算法的正确性.     

Establishmen and vertification of an improved similitude law for dynamic ice force model test

To study the similitude laws for dynamic ice force model test which is a hot problem in ice mechanics.In this paper,a new modified similitude law for dynamic ice force model test is proposed based on ice-induced virbration theory and two reasonable assumptions.And the new law is vertified with an ice-induced pier virbration example.The numerical calculation results show that,firstly,the error of frequency factor between test value and theory value is small as well as that of displacement and velocity;Secondly,the time scale completely meet the similitude relation,the waveforms anastomotic well,and the phenomenon of offset and omit do not occur;Thirdly,as the damping ratio between prototype and model is nearly equal,the improved similitude law will still be applied.Therefore,the new modified similitude law is feasible to study dynamic ice force model test and can provide reference for the ice mechanics.