Fabrication and microwave absorption properties of magnetite nanoparticle–carbon nanotube–hollow carbon fiber composites

Absorbents with “tree-like” structures, which were composed of hollow porous carbon fibers (HPCFs) acting as “trunk” structures, carbon nanotubes (CNTs) as “branch” structures and magnetite (Fe₃O₄) nanoparticles playing the role of “fruit” structures were prepared by chemical vapor deposition technique and chemical reaction. Microwave reflection loss, permittivity and permeability of Fe₃O₄–CNTs–HPCFs composites were investigated in the frequency range of 2–18 GHz. It was proven that prepared absorbents possessed the excellent electromagnetic wave absorbing performances. The bandwidth with a reflection loss less than −15 dB covers a wide frequency range from 10.2 to 18 GHz with the thickness of 1.5–3.0 mm, and the minimum reflection loss is −50.9 dB at 14.03 GHz with a 2.5 mm thick sample layer. Microwave absorbing mechanism of the Fe₃O₄–CNTs–HPCFs composites is concluded as dielectric polarization and the synergetic interactions exist between Fe₃O₄ and CNTs–HPCFs.     

微米级冷轧带钢厚度控制系统

分析、讨论了冷轧应用的各种厚度控制的优缺点，介绍质量流量厚度控制原理和控制精度极高的微米级带钢厚控（μＡＧＣ）系统及其可能产生的经济效益。     

一个全数字化交流永磁伺服系统

介绍了开发的全数字交流伺服系统的组成、基本原理及软、硬件结构。通过与模拟交流伺服系统的比较，说明了全数字交流伺服系统可编程能力强、系统稳定性好、系统性能提高等特点。     

CASE与MIS的开发

本文介绍ＣＡＳＥ技术的基本思想与构成，ＣＡＳＥ工具在ＭＩＳ开发中的作用，概要介绍国内流行的ＣＡＳＥ产品并对其作出评述。     

GCK－Ⅱ光电测宽仪──用CCD改造引进的二手测宽仪

本文介绍了用电荷耦合器件（ＣＣＤ）改造引进的日本二手测宽仪，并已用于太钢热连轧生产现场，取得了良好的应用效果。     

三维标量场并行等值面提取与绘制技术

通过研究并行等值面提取与绘制的各项关键技术要点,面向三维标量场的特点,在sort-last并行绘制模式的基础上提出一个三维标量场并行等值面提取与绘制框架.该框架在任务分配时采用静态分配的模式,在等值面提取时采用Marching Tetrahedra等值面提取算法,在并行绘制与场景合成时采用预先构建绘制节点控制模型的混合场景并行绘制合成算法.实验结果表明,该框架能够有效地提高大规模时变三维标量场的等值面提取与绘制效率,满足实际应用的需要.     

船舶抗沉辅助决策系统的研究与设计

抗沉辅助决策系统是船舶常规和紧急状态下进行损管行动的关键性依据。目前抗沉计算分析系统,可对船舶基础状态、浮稳性等信息进行管理,并进行仿真和辅助决策,但大多存在算法效率低,决策生成速度和精度不足、人机交互接口脱离实际等问题。本文从船舶抗沉操作的实际执行过程出发,制定抗沉算法,根据实时装载和破损情况,对液舱采用注入水或排水的损管操作,生成调整措施,使船舶恢复良好的浮态与稳性。系统基于面向对象过程控制平台设计和实现,仿真结果验证了系统的有效性和高效性。     

Robust Redundancy Scheme for the Repair Process: Hierarchical Codes in the Bandwidth-Limited Systems

High performance computing can be well supported by the Grid or cloud computing systems. However, these systems have to overcome the failure risks, where data is stored in the “unreliable” storage nodes that can leave the system at any moment and the nodes’ network bandwidth is limited. In this case, the basic way to assure data reliability is to add redundancy using either replication or erasure codes. As compared to replication, erasure codes are more space efficient. Erasure codes break data into blocks, encode these blocks and distribute them into different storage nodes. When storage nodes permanently or temporarily abandon the system, new redundant blocks must be created to guarantee the data reliability, which is referred to as repair. Later when the churn nodes rejoin the system, the blocks stored in these nodes can reintegrate the data group to enhance the data reliability. For “classical” erasure codes, generating a new block requires to transmit a number of k blocks over the network, which brings lots of repair traffic, high computation complexity and high failure probability for the repair process. Then a near-optimal erasure code named Hierarchical Codes, has been proposed that can significantly reduce the repair traffic by reducing the number of nodes participating in the repair process, which is referred to as the repair degree d. To overcome the complexity of reintegration and provide an adaptive reliability for Hierarchical Codes, we refine two concepts called location and relocation, and then propose an integrated maintenance scheme for the repair process. Our experiments show that Hierarchical Code is the most robust redundancy scheme for the repair process as compared to other famous coding schemes.     

单级Cuk集成式升压逆变器的电路拓扑研究

针对低输入电压的逆变场合,提出一种单级Cuk集成式升压逆变器拓扑结构。其通过共用功率元件,将传统逆变器与2个Cuk变换电路集成,并借助改变电容放电路径实现升压逆变。与其他单级升压逆变结构相比,该结构所用器件少,结构紧凑且对称。介绍了该逆变器的电路结构,分析了不同导电模式下的电路工作状态以及升压网络的临界状态,最后在理论分析的基础上,对集成式逆变拓扑进行了仿真和实验验证,验证了该逆变器理论分析的正确性。该变换器具有升压能力高、集成度高的优点。     

基于无线传感器网络的水质监测系统设计

使用传统的有线水质监测系统进行水环境污染检测时,存在监测点数量多、监测时间长等问题。为此,提出一种基于无线传感器网络的水质监测系统。通过无线传感器节点对被监测水域进行水质参数的数据采集,将采集到的数据经过Zigbee网络进行汇总及处理,并经过GPRS网络及时地远程传送给监管部门,从而实现对河流水质情况的实时、有效的监督和管理。对水质监测系统的软硬件电路设计进行介绍,并实现对系统的软硬件连调。实验结果证明,该系统能够满足组网要求,可较好地应用于水质监测领域。