浅谈数据库安全审计与访问控制的实施及意义

数据安全审计与访问控制系统,可以使风险管理要实现从被动转变到主动,开展事中和事前的监督和检查,防患于未然,充分发挥管理监督和防范风险的效能。     

撞击流反应器流场的有限元分析初探

撞击流已被证明是强化相间热质传递最有效的方法之一，作为一种新型的反应器——浸没循环撞击流反应器，在液相和液固相反应极具应用开发潜力。本文用有限元软件ANSYS／FLOTRAN对其三维流场进行模拟和分析。结果表明SCISR流场中各参数关于Y轴完全对称；撞击区速度和压力都较大，撞击区静压高，且在驻点达到最大值。     

液体连续相撞击流特性及其在超细粉体制备中的应用

20世纪90年代以来撞击流领域研究重点转向以液体为连续相。液体连续相撞击流(US)具有有效促进微观混合和存在压力波动的特性,从而有利于超细粉体的制备。实验结果表明,浸没循环撞击流反应器(SCISR)是反应一沉淀法制取超细粉体的一种优越的反应技术装备。     

Fluorination of pressure-polymerized C60 phases

The reactivity of O-, T- and R-phases of the high pressure-high temperature (HPHT) polymerized C₆₀ towards gaseous fluorine in the temperature range of 50-250 °C was investigated. The reaction products were characterized by FTIR, powder X-ray diffraction, SEM, EDX, and VTP-EIMS to determine the bulk stoichiometries, bonding patterns, phase compositions, crystalline structures and thermal decomposition behavior of the fluorinated polymers. At 1 h isothermal treatment duration, fluorinated products with various bulk stoichiometries were obtained from different polymer phases with the R-phase showing the highest fluorine uptake. At 250 °C, all C₆₀ polymers showed partial decomposition to unfluorinated C₆₀ monomer under fluorine atmosphere. At 200 °C, the fluorination of R-phase yielded a pure fluoropolymer most likely having a {C₆₀F_x}_n (x = 36-44) composition. The same fluoropolymer was presumably obtained from O- and T-phases in lower yields. The linear chain structure was suggested for this new fluorocarbon polymer in agreement with the molecular mechanics modeling calculations.     

海水反渗透淡化系统的能耗

通过对海水反渗透淡化系统（SWRO）吨水成本的分析，提出降低SWRO能耗的解决措施，采用能量透平装置（TURBO）或压力转换器（PE）回收浓水的能量传递于进水，不仅可以降低吨水电耗，也可减小一次性投资。值得关注的是，压力转换器，回收效率可达94％，在海水淡化系统中对于降低能耗有更重要的意义。     

高固含乳液压敏胶的粒径分析

运用多阶段乳液聚合法可以有效合成高固含乳液乳液粒径无论是单元分散还是多元分散均能实现高固含化在保持乳液稳定的条件下，如果乳液粒径是单元分散，当粒径足够大或者粒径分布足够宽时，乳液实现高固含的同时，可以达到低黏度目的如果是多元分散，粒径分布一般较宽，非常有利于实现乳液低黏度下的高固含化，当乳液的大粒子质量分数在80％左右时最容易达到目的.     

Determination of Minimum Spouting Velocities in Conical Spouted Beds

Minimum spouting velocities in conical spouted beds have been obtained from pressure drops versus the superficial gas velocity curves, based on both increasing and decreasing the superficial gas velocity. It has been shown that the minimum spouting velocity from decreasing the superficial gas velocity is lower than from increasing the superficial gas velocity in most cases. This phenomenon is similar to that in conventional spouted beds and different from the early works. The experimental results also showed that there isn't significant difference in the pressure drop and U_ms under identical operating conditions between semi‐circular and circular conical spouted beds, and the same U_ms can be obtained from absolute pressure drops at any position above the gas inlet. The U_ms is found to increase with increasing the cone angle and static bed height, as well as the gas inlet diameter to a less extent.     

注塑产品色差控制技术研究

色差是注塑中最常见缺陷，因其牵涉因素众多，十分难以掌握。本文从实用角度出发，讨论了影响色差主要因素和控制色差的实用技术．为减少色差问题的产生提供了一些好的经验和方法。     

Effect of agitation in the hydrogenation of castor oil

Castor oil was hydrogenated to evaluate the effect of agitation during hydrogenation. The turbine and propeller impellers were evaluated during hydrogenation of castor oil at various temperatures, pressures, and catalyst concentrations. The effect of impeller position in the agitator at definite oil depth was also evaluated. Hydrogenation of castor oil at 130°C, 2.0 kg/cm² hydrogen gas pressure with 0.5% Ni catalyst for 6 h while using two turbine impellers fitted in an agitator, one close to the reactor bottom and another at a height just below the top oil layer, revolving at 350 rpm, resulted in a product of a iodine value of 4.1, hydroxyl value of 156.4, and slip point of 84°C.     

芳纶1313的超高温高压染色研究

本文采用超高温高压法对芳纶1313进行染色,分别研究了染料种类和染色温度对芳纶1313纱线染色日晒牢度、K/S值及染透性等方面影响,结果发现,分散染料所染纱线的各项染色性能都比阳离子染料和还原染料好;随染色温度升高,日晒牢度、纤维表面颜色深度及其纤维染透性都得到了不同程度的改善,而纱线的断裂强度随染色温度的升高变化不大。