Recent advances in carbon nanotubes-based microwave absorbing composites

With the blossom of information industry, electromagnetic wave technology shows increasingly potential in many fields. Nevertheless, the trouble caused by electromagnetic waves has also drawn extensive attention. For instance, electromagnetic pollution can threaten information safety in vital fields and the normal function of delicate electronic devices. Consequently, electromagnetic pollution and interference become an urgent issue that needs to be addressed. Carbon nanotubes (CNTs) have become a potential candidate to deal with these problems due to many advantages, such as high dielectric loss, remarkable thermodynamic stability, and low density. With the appearance of climbing demands, however, the carbon nanotubes combining various composites have shown greater prospects than the single CNTs in microwave absorbing materials. In this short review, recent advances in CNTs-based microwave absorbing materials were comprehensively discussed. Typically, we introduced the electromagnetic wave absorption mechanism of CNTs-based microwave absorbing materials and generalized the development of CNTs-based microwave absorbers, including CNTs-based magnetic metal composites, CNTs-based ferrite composites, and CNTs-based polymer composites. Ultimately, the growing trend and bottleneck of CNTs-based composites for microwave absorption were analyzed to provide some available ideas to more scientific workers.     

Synergistic improvement of mechanical and thermal properties in epoxy composites via polyimide microspheres

Achieving synergetic improvements of mechanical strength, toughness, and thermal stability of epoxy resin has been a crucial but very challenging issue. Herein, to explore a new solution for circumventing this issue, polyimide microspheres were successfully prepared through the inverse nonaqueous emulsion process, and the structure, size distribution and morphologies of polyimide (PI) microspheres were comprehensively investigated. Then the PI microspheres were incorporated in epoxy resin matrix to systematically investigate the mechanical and thermal properties of obtained epoxy/PI microspheres composites. It was found that the PI microspheres can not only enhance the mechanical strength of epoxy resin, but also significantly improve the toughness. Specially, the epoxy-based composites containing 3 wt% PI microspheres exhibit a 47% increase in tensile strength, while the G_IC and Charpy impact strength increase by 106% and 200%, respectively. The toughing mechanism of epoxy/PI microspheres composites was discussed. Moreover, the PI microspheres can also endow the epoxy resin with excellent thermal stability and heat resistance. Thus, this work may open a new opportunity to synergistically enhance the mechanical and thermal properties of epoxy-based composites and may also give some valuable inspiration for the rational design of other high-performance thermosetting composites.     

光－生物降解发泡PS快餐具性能评价方法研究

本文通过对国内几家单位所开发的光－生物降解发泡聚苯乙烯餐盒使用性能和降解性能的实验研究，初步提出对该类餐盒应从理化指标、毒性指标及样品经氙灯光源加速老化试验、自然气候曝露实验和野外降解实验后红外光谱分析、样品厚度变化及分子量变化情况的测试等几个方面进行评价，为该类产品的研制、开发及应用提供了依据。     

KT178 型取心钻具在共和干热岩钻井中的应用

青海共和盆地干热岩资源富集于花岗岩地层,硬度高,研磨性强,部分层段裂隙发育,取心困难。针对干热岩地层和取心需求特点,研制了一套KT178型取心钻具,并配套设计了孕镶金刚石取心钻头。该钻具为单动双管取心钻具,可配套井底动力钻具使用,设计中注重对钻具外管、卡簧等关键部件的强度校核。在GH-01井和GH-02井中,经过两轮试验和优化,钻具逐渐成熟,获取了较完整的岩心样本,满足干热岩勘探取心要求,具备了向页岩气、水资源勘察等具有间断取心需求的同类工程推广应用的条件。     

水性含磷功能性聚合物的制备及应用

水性含磷功能性聚合物是一种环境友好材料,且具有阻燃、耐热、防腐、生物相容性好以及改善粘接性能等多种特性.本文介绍了水性含磷功能性聚合物的结构和制备方法,综述了其在粘合剂、涂料以及生物医用材料等方面的应用报道,并展望了其发展前景.     

某特高压换流站接地极入地馈线电缆故障分析及处理

接地极在直流输电系统中有很重要的作用,直接影响直流输电系统安全稳定运行。对某特高压换流站在大负荷试验期间发生的一起接地极入地馈线电缆故障情况进行梳理,通过试验数据检查分析,确定故障原因为电缆1处焊接点短路,对故障点进行处理后,恢复正常运行,提高了直流输电系统运行可靠性。     

新型复合絮凝剂凹凸棒土／聚合硫酸铁铝的制备

以硫酸铁、硫酸铝和凹凸棒土为原料,制备了凹凸棒土／聚合硫酸铁铝新型复合絮凝剂。通过单因素实验得到优化合成条件：凹凸棒土投加量487．5mg,反应时间2h,熟化时间19h,盐基度15％,反应温度50℃。在此条件下制备的复合絮凝剂絮凝效果好,除浊率可达81．62％。     

SAM扫描器件芯/焊结合空洞的失效分析

超声无损检测是70种无损探伤技术的最热点。扫描声学显微镜(SAM)的原理是声阻抗成像,要求缺陷尺度大于超声波的波长。结合SAM技术中的A-扫描波形分析和C-扫描特征成像,针对由封装引入的分层和空洞缺陷进行失效分析。研究发现:分层定位的关键是A-扫描波形分析中对各界面处反射波的时间位置的判断;基于分层定位的芯/焊结合空洞缺陷的判别,关键是C-扫描图像中灰阶色带的区分(反射率差值)。     

规划管理创新框架下的规划设计院组织结构再造——以地级市城市规划设计院为例

现阶段规划设计院传统的组织模式和管理理念已越来越不能适应迅速变化的竞争环境.在规划设计院生产组织模式及方法的优化过程中,应引入科学、高效的现代项目管理理念,建立适合规划设计院运作的组织结构,以提高规划设计院的工作效率和效益,促进规划管理的创新.由于集权化程度高和各处室职责分工不明晰,地级市城市规划设计院现行组织结构存在各部门间横向协调困难、项目系统性管理缺失和项目监控长效机制未能建立等问题.因此,应通过对权变因素的分析,在“专业矩阵制”组织结构或“超矩阵制”组织结构之间寻求一个平衡点,选择基于项目管理的组织结构,引入并完善适合地级市城市规划设计院的项目管理体系.     

红外遥控发/收数据通信系统的EDA实现

分析了红外线遥控系统的数据编码和传输机制;设计了基于红外线的数据发送和接收系统;用VerilogHDL语言设计了信号编/解码核心电路,外围电路包括红外发/收器件、晶振、显示电路等;在ModelSim6.2仿真工具中进行了仿真测试;用Xilinx ISE9.1软件进行了综合、适配和FPGA器件下载测试,并用Agilent 16823A逻辑分析仪进行了数据采集显示验证,结果表明该电路实现了数据发送和接收功能,符合红外遥控数据传输协议.