虚拟平台技术的研究与应用

虚拟平台技术的研究与应用面向计算机专业教学和实训领域,特别是针对计算机专业实训室的四合一软、硬件结合实训方案,很好地解决了目前计算机专业实训中的很多根本性问题,开拓了目前实训中所没有实现的功能,提高了实训室的利用率。     

中职计算机技能大赛推进教学改革的研究

现在很多职业院校都参加了计算机技能大赛,如何通过技能大赛有效的推进职业教育教学改革,把在参加技能大赛中学习到的教学方法和经验有效的融入到日常教学改革中,是广大职业教育工作者急需面对和解决的一个问题。通过分析计算机技能大赛对计算机教学改革的推进作用,对中职计算机教学改革进行了研究。     

Static output feedback sliding mode control for time‐varying delay systems with time‐delayed nonlinear disturbances

In this paper, a robust stabilization problem for a class of linear time‐varying delay systems with disturbances is studied using sliding mode techniques. Both matched and mismatched disturbances, involving time‐varying delay, are considered. The disturbances are nonlinear and have nonlinear bounds which are employed for the control design. A sliding surface is designed and the stability of the corresponding sliding motion is analysed based on the Razumikhin Theorem. Then a static output feedback sliding mode control with time delay is synthesized to drive the system to the sliding surface in finite time. Conservatism is reduced by using features of sliding mode control and systems structure. Simulation results show the effectiveness of the proposed approach. Copyright © 2009 John Wiley & Sons, Ltd.     

基于无线传感器网络的井下人员定位方法的研究

近年来,随着无线传感器技术的成熟,以及基于无线传感器网络的定位技术的发展,不少学者提出了基于无线传感器技术的煤矿井下人员定位方法,本文对其中部分方法进行了分析,发现其中存在的一些不足。     

Highly efficient switched‐mode transmitter using a current mode class‐D RF amplifier

This article presents a switched‐mode transmitter architecture using a current mode class‐D (CMCD) amplifier. To achieve high average efficiency for a modulated signal the envelope of the complex baseband signal is transformed into pulses such that the CMCD amplifier is operated either at its peak efficiency or completely switched off. The CMCD amplifier has been designed based on single‐tone active harmonic load‐pull measurements to achieve a power‐added efficiency (PAE) of 61.5% with 25 W output power at 900 MHz using LDMOS FETs. Removing the losses of the demodulation filter and of the amplifier a 10% higher efficiency than in an ideal class‐B amplifier can be obtained for burst‐mode operation with a peak‐to‐average power ratio of 10 dB. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

A current‐mode tunable low‐supply‐voltage ring oscillator

A new circuit topology using a current‐mode low‐pass filter for sinusoids has been presented. The technique is relatively simple, in the proposed circuit, only three identical current‐mode low‐pass filters are connected to each other to realize the small signal path. No external passive components are required except for three capacitors. When compared with LC oscillators, the die area of this work, without inductors, is much smaller. When compared with voltage‐mode ring oscillators, the supply voltage of this work is much lower. As a particular example, a 2.4 GHz, 1.2‐V power supply, 5‐mW sinusoidal oscillator is demonstrated. The oscillation frequency is tuned by the value of that three capacitors, over ～900 MHz, and the tuning range is 37.5%. The phase noise results in ?94 and ?120 dBc/Hz at 1 and 10 MHz from the carrier, respectively. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

Chattering reduction of sliding mode control by low‐pass filtering the control signal

The conventional approach to reducing control signal chattering in sliding mode control is to use the boundary layer design. However, when there is high‐level measurement noise, the boundary layer design becomes ineffective in chattering reduction. This paper, therefore, proposes a new design for chattering reduction by low‐pass filtering the control signal. The new design is non‐trivial since it requires estimation of the sliding variable via a disturbance estimator. The new sliding mode control has the same performance as the boundary layer design in noise‐free environments, and outperforms the boundary layer design in noisy environments. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Disturbance decoupled fault reconstruction using sliding mode observers

This paper investigates and presents conditions that guarantee disturbance decoupled fault reconstruction using sliding mode observers, which are less stringent than those of previous work, and show that disturbance reconstruction is not necessary. An aircraft model validates the ideas proposed in this paper. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

煤矿井下安全避险“六大系统”的作用和配置方案

研究了煤矿安全监控系统在瓦斯、火灾等重特大事故监控与预警和事故调查中的作用,提出了系统的配置方案及基于煤矿安全监控系统的煤矿瓦斯爆炸等事故直接原因的认定方法;研究了煤矿井下人员位置监测系统在遏制超定员生产、事故应急救援等方面的作用,提出了系统设置方法;提出了以矿用调度通信系统和矿井广播通信系统为基础、矿井移动通信系统为补充的矿井通信联络方案,提出了严禁采用矿用IP电话通信系统和矿井移动通信系统替代矿用调度通信系统的观点;提出了高瓦斯矿井的入井人员宜携带隔离式自救器,且隔离式自救器宜选用压缩氧隔离式自救器的方案;提出了避难硐室的装备要求和避难硐室性能价格比优于救生舱的观点;介绍了矿井压风自救系统和供水施救系统。     

可靠实现煤矿双机热备系统的方法

在分析商用双机热备系统在煤矿应用的局限性基础上,提出了一种适用于中小煤矿的双机热备系统纯软件实现方法。该方法采用单/双工混合运行模式保证双机实时性能和数据一致性,采用心跳线连接和对等网络消息传递机制实现运行故障监测与传递功能,采用数据自动同步技术减少人工干预和提高系统可维护性,并采用虚拟IP地址技术实现应用层透明访问和无缝切换功能。实验与应用案例证明该方法符合相关行业安全标准并具备现实可行性。