PVC╱NBR╱BR三元共混弹性体的制备

采用结合丙烯腈含量为26％的NBR、分子量适中的悬浮法Ⅲ型PVC和BR共混,制得了综合性能较PVC/NBR并用胶优异的弹性体。优选的工艺条件为:PVC/NBR/BR=30/60/10(质量比);补强剂选用炭黑40份,超细碳酸钙50份,轻质碳酸钙20份;硫化体系选用过氧化物加少量硫磺;混炼温度为140—170℃,混炼时间为10—15min。通过电子显微镜和动态力学分析,弹性体存在两个T,PVC为分散相,橡胶为连续相。     

浅谈数据中心网络架构的发展

网络是数据中心的一个重要基础设施,而通常分为两大部分：前端计算网络以及后端存储网络.后端的存储网络目前主要是FC网络,不过随着IP技术的发展,采用FCoE技术融合前后端网络成为一种趋势.本文主要关注前端计算网络.     

A Thermo-Mechanical Study of Some Epoxy Adhesives Subjected to Combined Dynamic and Static Stresses

The object of the present study was to investigate the effect of superimposed dynamic and static stresses on mechanical and thermal properties of some epoxy adhesives. It was found that combinations of shear creep and torsional oscillations, applied simultaneously to adhesive joints at temperatures within the glassy range of the adhesive, led to strengthening of the joints in shear and to an increase in the glass transition temperature of the adhesive. Similar loading stresses applied at temperatures close to the T_g of the adhesive, led to opposite effects on the above mentioned properties of the joints. The width of the glassy-rubbery transition of the adhesives increased, in the whole range of temperatures used in this study and for all epoxy compositions, as a result of subjecting the joints to superimposed dynamic and static stresses. The broadening of the glass transition was interpreted as a result of the stiffening of polymer network during the combined stressing experiments. A linear relationship was found between the area of endothermal peaks in the first DSC scan of specimens subjected prior to test to superimposed dynamic and static stresses at temperatures below T_g, and the shear strength of the joints. In agreement with this observation and with literature data, a linear relationship was revealed also between the glass transition temperature of the resins (measured in the first DSC scan) and the shear strength of the joints. Based on experimental observations and on some literature information, it was suggested that the strengthening of the joint, as well as the changes in thermal properties of the adhesives, are mainly due to physical processes, such as short-range orientation of network chains and an increase in intermolecular interaction between highly polar sites of the network. The possibility that superimposed stressing led to changes in chemical crosslinking was discussed but it seems that no such reactions occurred.     

轻量级安全内存：RISC-V嵌入式微处理器安全增强

近年来,针对嵌入式设备中硬件的新型攻击不断出现,严重威胁嵌入式设备的安全.特别是随着非易失性存储器开始被配备到嵌入式设备中,就需要考虑如何保护配备非易失性存储器的嵌入式设备的安全.安全内存,就是这样一种通过保护内存来增强嵌入式设备安全性的有效手段.通过设计一种安全内存加密引擎来实现安全内存.在保证该安全内存加密引擎足够轻量、开销低的同时,将其集成到RISC-V嵌入式微处理器中,并通过FPGA对该安全内存加密引擎进行了评估.评估结果表明,安全内存加密引擎能够在提升RISC-V嵌入式微处理器安全性的同时,保证其合理的访存性能以及较小的面积开销.研究结果具有良好的参考价值和应用前景.     

基于tPUF的物联网设备安全接入方案

针对现有的物联网设备安全接入方案不适用于资源受限的物联网设备的问题,提出一种基于tPUF的物联网设备安全接入方案。利用物理不可克隆函数技术（Physical Unclonable Function,PUF）,物联网设备不需要存储任何秘密信息,实现设备与认证端的双向认证以及协商会话秘钥;利用可信网络连接技术（Trusted Network Connect,TNC）,完成认证端对物联网设备的身份认证、平台身份认证、完整性认证。安全性分析表明,方案能够有效抵抗篡改、复制、物理攻击等。实验结果表明,相较于其他方案,该方案明显降低了设备的资源开销。     

选煤厂信息物理系统任务调度研究

建立了选煤厂信息物理系统模型,将动态联盟思想引入选煤厂信息物理系统任务调度中,并提出了一种基于改进离散粒子群优化算法的选煤厂信息物理系统任务调度算法。该算法首先采用离散粒子群优化算法进行全局寻优,然后采用禁忌搜索算法进行局部搜索,求得全局最优解。仿真结果表明,该算法提高了任务调度的收敛速度、精度以及处理器的平均利用率。     

智慧校园建设的方案与探索

随着高校数字化、信息化建设的发展不断推进,智慧校园成为数字校园发展的必然趋势。该文简要介绍了智慧校园的概念,智慧校园的发展与设计方案。系统介绍了在原有校园数字网络的基础上,引入＂天翼校园云＂3G校园信息化移动应用系统和＂校园翼卡通＂应用系统,构建智慧校园的一种特殊模式及其应用。     

Social Engineering: Hacking the Wetware!

ABSTRACT

Social engineering is a methodology that allows an attacker to bypass technical controls by attacking the human element in an organization. There are many techniques commonly used in social engineering including but not limited to Trojan and phishing email messages, impersonation, persuasion, bribery, shoulder surfing, and dumpster diving. Hackers rely on social engineering attacks to bypass technical controls by focusing on the human factors. Social engineers often exploit the natural tendency people have toward trusting others who seem likeable or credible, deferring to authority or need to acquiesce to social conformity. Mitigation of social engineering begins with good policy and awareness training, but there are a number of other approaches an organization can take to defend against this type of an attack. Social engineering attacks are likely to increase, and it is becoming increasingly important for organizations to address this issue.     

计算机内存的优化及管理浅析

信息总量、网络浏览人数以及人们对网络享受需求的增加,促使着信息制作水平的提高,制作水平的提高在给人们带来了更好的视觉和听觉享受的同时,也对计算机的硬件系统提出了巨大的考验.计算机内存作为计算机硬件系统的重要组成部分,能否对内存做好合理的划分,对计算机的体验具有重要的意义.     

Robust Saturated PI Joint Velocity Control for Robot Manipulators

It is well known that many industrial manipulators use an embedded linear proportional‐integral (PI) joint velocity controller to guarantee motion control through proper velocity commands. However, although this control scheme has been very successful in practice, not much attention has been paid to designing new PI velocity control structures. The problem of analyzing a saturated PI velocity joint velocity controller is addressed in this paper. By using the theory of singularly perturbed systems, the closed‐loop system is studied. The robot dynamics assumed in this paper take into account bounded time–varying disturbances which may include the friction at the joints. An experimental study in a planar two degrees‐of‐freedom direct‐drive robot is also presented, confirming the advantage of the new saturated PI joint velocity controller.