基于ACL的小型企业MIS的访问控制

目前,在企业MIS中的访问控制主要有DAC和RBAC两种模型。本文分析比较了这两种模型的优缺点及其关系,给出了用ACL来实现小型企业MIS系统中的访问控制的实例。     

善用电子媒介促进儿童学习

电子媒介对儿童学习的影响有积极的方面也有消极的方面,成人要善用电子媒介,控制其消极影响,促进其积极作用的发挥。具体策略包括四个方面:树立正确的电子媒介使用观,引导儿童恰当地使用电子媒介,利用电子媒介培养儿童的阅读兴趣,同时还要做好与电子媒介节目制作单位的沟通。     

浅谈个人计算机应用及其网络安全

总结和探讨如何安全、稳定地使用计算机和网络资源.     

高锑铋复杂含银物料中有价金属的综合回收

以某厂铜阳极泥处理后得到的高锑铋复杂含银物料为原料,采用甘油的碱溶液浸出的方法,对含银复杂物料中的铜、锑、铋等有价金属的浸出进行较为系统的研究并优化了相关的工艺条件。研究了NaOH浓度、C3H8O3浓度、液固比、反应时间与温度等因素对浸出的影响,在优化条件下浸出时,铜、铋、锑的浸出率分别为96.73%、96.44%、85.91%。     

应用型本科院校"机械工程基础"课程的教学改革

培养具有厚基础、宽口径、高素质、能力强，特别是具有工程实践能力和创新能力的高素质工程技术人才，是高等工程教育的主要教学目标。根据这一目标，结合应用型本科院校的教学特点，从人才培养模式的整体目标出发，以转变教育思想和观念为先导，对交通专业“机械工程基础”课程的教学内容、方法与手段、考核方法等方面进行了改革，形成了新的“机械工程基础”理论教学与实践教学综合改革的教学模式。     

2^#1880m^3高炉薄壁喷枪的研究与应用

为了进一步提高煤比，2^#1880m^3高炉从高炉操作制度和喷枪等多方面进行了研究，在高炉顺行状态较好的情况下，煤粉在风口前的燃烧率是限制提高煤比的一个重要原因，通过对喷枪的局部改造，扩大喷枪内径，提高了煤粉的燃烧率，在煤比攻关实验中起到了显著作用。     

Factors Influencing High Temperature Thermo Plasticity of BNbRE Steel at the Third Brittle Zone

In view of fine cracks occurred on the surface of BNbRE continuous casting slabs for heavy rail in the practiced production, the effect of two factors, i. e. deformation temperature, deformation velocity, on thermo plasticity of BNbRE steel at the third brittle zone was quantitatively investigated on GLEEBLE-1500D thermal-mechanical simulator after measuring the RA-T curve of BNbRE steel. The results provide experimental data for optimizing the technology of continuous casting secondary cooling zone and avoiding the occurrence of fine surface cracks.     

MTO再制造系统最优生产计划提前期研究——基于最小相对熵的方法

研究了MTO再制造系统关于单一核心部件在分拆和采购提前期均不确定下的生产运作;由于回收部件并非100%可用,使得以最小化再制造成本为目标得到的生产计划提前期呈现双峰分布的形式;本文将最小相对熵(MRE)方法应用于生产计划提前期分布的拟合,仿真算例表明:与传统的正态分布和Pearson近似方法相比,MRE近似的结果更为接近目标服务水平和真实的成本曲线,所得结论对再制造企业安排生产计划、设备投资以及旧产品回收策略等有现实的指导意义.     

Orthogonal analysis of water model study on the optimization of flow control devices in a six-strand tundish

Improper flow control devices in a multi-strand tundish can cause some problems, for example, liquid steel cannot reach every nozzle at the same time and the liquid steel in nozzles far away from the entry zone has a lower temperature. The water model experiment of a six-strand tundish of Tianjin Iron ＆ Steel Co. Ltd. was performed, a new ＂U＂ type baffle was obtained, and its parameters were defined by perpendicular analysis. The ＂U＂ baffle can not only improve those imperfections, but also prolong the residence time of nonmetallic inclusions, which is good for their flotation and separation.     

GaN-based Indium-tin-oxide light emitting diodes with nanostructured silicon upper contacts

GaN-based indium-tin-oxide (ITO) light emitting diodes (LEDs) with p-GaN, n⁺-short period superlattice (SPS) and nanostructured silicon contact layers were fabricated. It was found that surface of the ITO LED with nanostructured silicon layer was very rough. It was also found that 20 mA forward voltages measured from ITO LEDs with p-GaN, n⁺-SPS and nanostructured silicon contact layers were 6.01, 3.25 and 3.26 V, respectively. Compared with ITO LED with n⁺-SPS, it was found that output power of ITO LED with nanostructured silicon contact was 17% larger. Furthermore, it was found that ITO LED with nanostructured silicon contact was more reliable.