Light Controlled Biohybrid Microbots

Biohybrid microbots integrate biological actuators and sensors into synthetic chassis with the aim of providing the building blocks of next-generation micro-robotics. One of the main challenges is the development of self-assembled systems with consistent behavior and such that they can be controlled independently to perform complex tasks. Herein, it is shown that, using light-driven bacteria as propellers, 3D printed microbots can be steered by unbalancing light intensity over different microbot parts. An optimal feedback loop is designed in which a central computer projects onto each microbot a tailor-made light pattern, calculated from its position and orientation. In this way, multiple microbots can be independently guided through a series of spatially distributed checkpoints. By exploiting a natural light-driven proton pump, these bio-hybrid microbots are able to extract mechanical energy from light with such high efficiency that, in principle, hundreds of these systems can be controlled simultaneously with a total optical power of just a few milliwatts.     

一种面向云平台的虚拟机内存SLA审计机制

针对云计算的服务模式屏蔽了云租户的物理硬件视图,不可信的云服务提供商(cloud service provider,CSP)可能利用廉价的硬盘资源通过虚拟化技术,违背服务等级协议约定(service level agreement,SLA)按物理内存定价标准为云租户提供服务这一问题,为了审计CSP提供内存服务的SLA合约性,提出了由Xen层到物理硬件层的内存轻量级测量的SLA合约性审计方案.同时引入可信启动机制和HyperSentry用于保证审计系统的可信启动和完整性运行,提出了带云租户签名机制的Diffie-Hellman密钥交换协议支持策略安全和可信告警.实验结果表明,在虚拟机运行环境下该方法能高效地进行内存SLA合约性审计,同时具有较高的云租户自定义策略扩展性和较低的性能开销.     

用于光子晶体的多孔硅制备条件研究

利用扫描电镜观察了不同电压强度、腐蚀液浓度条件下制备的用于二维光子晶体的多孔硅的微观形貌。研究表明在恒压供电模式下更有利于硅基二维光子晶体的制备;随着腐蚀电压强度的增长,孔径和孔深都呈现增长的趋势,增长的幅度逐渐减小,腐蚀效率比的增长幅度也有逐渐变小的趋势;随着腐蚀溶液浓度的减小,腐蚀速率在降低,但腐蚀效率比在增大,虽然多孔硅的生长速度变慢,但是多孔硅的质量更好。     

星载全极化微波散射计系统仿真与性能分析

本文对全极化微波散射计遥感海面风场的原理及其特点进行研究,建立了星载全极化微波散射计的系统仿真模型.对比了SeaWinds散射计参数下全极化与同极化的风场反演质量,结果表明全极化微波散射计在星下点以及刈幅远端的区域有良好的风场反演性能,并可提升高风速条件下的风场反演精度.最后分析了极化通道隔离度对全极化散射计系统性能的影响.     

降雨衰减对移动卫星系统通信的影响及补偿

针对移动卫星系统的特点，分析了降雨引起的信号衰减的原因，给出了雨衰的计算方法。Ka波段一般用于移动通信业务，从分析结果上看该波段信号受降雨影响较大。提出几种补偿雨衰的方法，给出了上行功率控制法的系统原理图。     

Analysis of factors influencing the Henry Hub natural gas price based on factor analysis

Henry Hub as an important transaction hub for natural gas sets the gas price standard in the USA. In this paper, the factors influencing Henry Hub natural gas prices are analyzed, and the major factors determining the price levels in the period between January 1997 and December 2016 are studied. It is found that economic conditions, total energy demand, US dollar exchange rate and gas consumption are the major factors. The mechanism of each factor influencing the Henry Hub natural gas price is also explored in the paper.     

Gain-compensated sample-and-hold circuit for high frequency application

A novel and fast and accurate sample-and-hold circuit is presented which can be designed using conventional single stage amplifiers. The offset contribution to the output voltage is intrinsically compensated and the clock-feedthrough error can be reduced by slightly changing the clock phase scheme.<>     

电磁型微电机定子绕组的研制

本文主要阐述应用微细加工技术研究和开发电磁型微电机定子绕组的制备工艺，重点介绍制备定子绕组所涉及到的各种材料及其用途。采用掩模电镀技术解决了平面工艺难以解决的线圈绕组。本研究结果为双层十七圈三对六组绕组系统。最小线宽为３μｍ，微电机直径为２ｍ，最大工作电流１２０ｍＡ，电阻值在２４－２５Ω之间。输出力矩为１．５μＮＭ，转子转速每分钟可达５００转。     

薄膜磁头磁轭制备工艺研究

本文重点讨论了用不同的工艺方法来制备薄膜磁头中的关键元件-磁轭。采用多次光刻的方法克服湿法工艺中磁性膜NiFe层的侧向钻蚀问题，从而实现对磁轭几何尺寸的精确控制，并对几种工艺方法的优缺点作了比较详细的分析。     

同步磁阻电机直接转矩控制系统研究

鉴于矢量控制对电机参数依赖性强的问题,借鉴现有永磁同步电机数学模型及其直接转矩控制的相关理论,分析同步磁阻电机的数学模型,提出了同步磁阻电机的直接转矩控制方法,包括空间电压矢量的计算、磁链和转矩的滞环控制等;并基于位置信息的估算,设计了速度的闭环控制器。构建了系统的仿真模型,并对电机的稳态和动态性能进行了仿真分析。由仿真结果可知,所提方法设计的系统能够在较宽的转速范围内变速运行。