铝合金电磁低压铸造工艺试验及应用

研究了铝合金电磁低压铸造工艺参数关系及控制方法;通过试验及数学分析研究确定了电磁驱动力与电流、流量与电流之间的关系及计算模型,并进行了电磁低压铸造和气压低压铸造实际铸件性能对比。结果表明,电磁低压铸造的流量大小与电极电流成线性关系;并且当电极电流一定时,随出液口高度增加,流量减小,电磁低压铸造生产的铸件性能得到明显提高;电磁低压铸造方法比传统气压低压铸造控制过程更精确。     

一种新型振动下料机的PLC控制

在分析了新型振动下料机采用继电器－接触器控制方式存在不足的基础上，指出了对其进行PLC控制的必要性。分析了该振动下料机的基本构成及工作原理，建立了相应的液压系统。针对下料机正常工作对控制系统要求，确定了PLC的输入量及输出量，建立了PLC控制的硬件接线图，编制了相应的梯形图控制软件。大量实验验证了该控制方案的可行性和实用性。     

Micro cam system driven by electrostatic comb-drive actuators based on SOI-MEMS technology

Microsystem Technologies - This paper reports a design and fabrication process of a micro cam system (MCS) with a flat-faced translating follower. The cam rim with cover diameter of 2.4 mm...     

基于单片机的晶闸管触发器的设计与实现

设计了一种集同步电压检测、移相延迟角定时环节、触发脉冲时序分配等功能于一身的单片机控制的晶闸管触发器。采用软件实现了定时/计数、触发脉冲分配、双窄脉冲形成等功能。采用AT89C2051单片机实现三相全控桥式电路晶闸管的移相触发控制,降低了对单片机资源的需求。提出了用一个同步电压信号,通过触发脉冲延迟角的调整算法,实现了对称三相触发脉冲输出。设计中采用定时器计时同步方式,消除了干扰信号的影响,保证了三相桥式全控整流系统可靠工作。     

Stability,L2‐gain and asynchronous H ∞ control for continuous‐time switched systems

This paper is concerned with the stability and L₂‐gain problems for a class of continuous‐time linear switched systems with the existed asynchronous behaviors, where ‘asynchronous’ means that the switching of the controllers to be designed has a lag to the switching of the system modes. Firstly, a new sufficient condition on the asymptotic stability and weighted L₂‐gain analysis is obtained by using multiple Lyapunov functions combined with the average dwell time technique. Moreover, a result that is formulated in form of linear matrix inequalities is derived for the problem of asynchronous H _∞ control. Based on the result, the mode‐dependent controllers can be designed. Finally, an illustrative numerical example is presented to show the effectiveness of the obtained results.Copyright © 2013 John Wiley & Sons, Ltd.     

On the Controllability of Nonlocal Second‐Order Impulsive Neutral Stochastic Integro‐Differential Equations with Infinite Delay

In this paper, we investigate the controllability for a class of nonlocal second‐order impulsive neutral stochastic integro‐differential equations with infinite delay in Hilbert spaces. More precisely, a set of sufficient conditions for the controllability results of nonlocal second‐order impulsive neutral stochastic integro‐differential equations with infinite delay are derived by means of the Banach fixed point theorem combined with theories of a strongly continuous cosine family of bounded linear operators. As an application, an example is provided to illustrate the obtained theory.     

一种智能寻迹与搬运机器人的控制系统设计

提出寻迹与搬运机器人的一种智能控制系统设计;该系统主要由单片机、传感器和执行舵机组成;通过分析直行、弯道与取物等工作模式,建立相应的舵机驱动控制;传感器将检测到的路线和工件信号传送给单片机进行处理;按照不同的优先级别,由单片机发出脉冲信号,控制舵机的速度与方向,完成抓取、转运工件的任务;实验结果表明:多路传感器的信息融合能有效识别寻迹路径,确定优先级别的控制;舵机的驱动控制能满足寻迹与搬运的要求;系统设计简单,实用可靠,具有良好的开放性与扩展性.     

基于网络化虚拟仪器的通信测试系统的实现

网络化虚拟仪器的使用可以大大提高通信测试设备的利用率,增加通信测试的灵活性。通过分析和比较各种虚拟仪器及网络化虚拟仪器系统的组建模式的特点,结合某卫星测控站现有通信测试系统的实际结构,选择基于HPVEE和三层C/S网络的虚拟仪器作为构建网络化虚拟仪器通信测试系统的基础,对系统网络软硬件进行设计,实现基于网络化虚拟仪器通信测试系统,完成该测控站从单一的通信测试操作单位向通信测试平台和通信测试软件研发中心的转变,并可为类似需求提供有效的技术支持。     

Enhanced security in internet voting protocol using blind signature and dynamic ballots

In this paper, we introduce an internet voting protocol which satisfies desired security requirements of electronic voting. In the newly proposed protocol, we allow the adversaries to get more power than in any previous works. They can be coercers or vote buyers outside, and corrupted parties inside our system. These adversaries also have ability to collude with each other to ruin the whole system. Our main contribution is to design an internet voting protocol which is unsusceptible to most of sophisticated attacks. We employ the blind signature technique and the dynamic ballots instead of complex cryptographic techniques to preserve privacy in electronic voting. Moreover, we also aim at the practical system by improving the blind signature scheme and removing physical assumptions which have often been used in the previous works.     

Analyzing sentiments in Web 2.0 social media data in Chinese: experiments on business and marketing related Chinese Web forums

Web 2.0 has brought a huge amount of user-generated, social media data that contains rich information about people’s opinions and ideas towards various products, services, and ongoing social and political events. Nowadays, many companies start to look into and try to leverage this new type of data to understand their customers in order to make better business strategies and services. As a nation with rapid economic growth in recently years, China has become visible and started to play an important role in the global business and economy. Also, with the large number of Chinese Internet users, a considerable amount of options about Chinese business and market have been expressed in social media sites. Thus, it will be of interest to explore and understand those user-generated contents in Chinese. In this study, we develop an integrated framework to analyze user sentiments from Chinese social media sites by leveraging sentiment analysis techniques. Based on the framework, we conduct experiments on two popular Chinese Web forums, both related to business and marketing. By utilizing Elastic Net together with a rich body of feature representations, we achieve the highest F-measures of 84.4 and 86.7 % for the two data sets, respectively. We also demonstrate the interpretability of Elastic Net by discussing the top-ranked features with positive or negative sentiments.