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双纵模激光热稳频光源 总被引:7,自引:0,他引:7
介绍一种双纵模激光器的稳频装置原理及其电源电路。对稳频机理进行了理论分析,并说明具体调整方法。该光源采用新的热频原理,在普通的全内腔He-Ne激光器上获得了与塞曼型稳频激光器同一量极的稳频精度,具有成本低,稳频装置简单的特点。 相似文献
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《计量技术》1985,(11)
北京大学和中国计量科学研究院于1985年6月17日至18日在北京联合召开了“塞曼稳频氦氖激光器系列鉴定会”。会议由北京邮电学院吴彝尊教授和清华大学梁晋文教授主持,王天眷等专家和科技工作者40余人参加了会议。主办单位提供给会议鉴定的有3种633nm塞曼稳频氦氖激光器样机。会前,大会测试组对这三种激光器样机进行了抽样测试,会上,代表们听取了课题组的研制报告和测试组的测试报告。通过认真热烈地讨论,代表们确认了以下指标: 1.横向塞曼稳频激光器(北京大学无线电系研制): 1秒取样的以阿仑方差表示的激光频率稳定度为1.8×10~(-11),频率再现性优于5×10~(-9)。 2.新型锁相双频激光器(中国计量科学研究院时频处光频室研制): 1秒取样的以阿仑方差表示的频率稳定度 相似文献
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中国计量科学研究院量子部世行贷款项目“改进和提高633纳米稳频氦氖激光波长” ,于1996年申请并进行技改。在较短的时间里 ,不仅改造并恢复使用了两套德国80年代中期援助的稳频激光器 ,而且研制出自动锁峰碘稳频系统(以下简称ALSS) ,使稳频激光的操作过程实现了自动化 ,在1997年由BIPM组织的国际比对中显示出优良的技术性能。由ALSS技术派生出的新型兰姆凹陷稳频激光系统 ,开创了该稳频激光应用的新局面。ALSS技术的研制成功 ,表明我国已拥有90年代技术水平的激光控制系统。1997年6月 ,知名学者、美… 相似文献
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基于智能模糊控制策略的有源消声 总被引:3,自引:0,他引:3
有源消声是一种有效的低频噪声控制方法,由于空间有源消声过程具有时变性和非线性,传统的自适应算法不能进行很有效的控制。本文采用智能模糊控制策略,建立了基于智能模糊控制策略的有源消声系统,通过实验与传统自适应控制算法的消声效果作对比分析,证明智能模糊控制器不但控制速度快,易于实现,而且消声效果明显优于后者,具有较大的应用推广价值。 相似文献
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This paper reviews robotic position and force control techniques. The existing fundamental force control algorithms are compared and discussed,including explicit / implicit control,stiffness control,impedance / admittance control,and hybrid position / force control. This work is intended to give a basic guidance for understanding and utilization of the fundamental robotic control algorithm. 相似文献
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噪声主动控制技术目前已用增加双隔板结构对声音进行衰减。在这项研究中,声音穿过双隔板进入房间有三种控制途径:在双隔板的空气间隙中应用声控源(腔控),在辐射板上应用振动控制源(板控),在接收房间内应用声控源(房控),都进行了实验研究和相互比较。每种方法中涉及到的机械装置都有例子,有效减少噪声的状况都经过考查。结果表明,每种方法(腔控、板控和房控)的模态重叠和涉及到的机械装置是两个重要的因素,它决定了每种方法有的有效性。 相似文献
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Douglas C. Montgomery J. B. Keats Mark Yatskievitch William S. Messina 《Quality and Reliability Engineering International》2000,16(6):515-525
Feedforward control is a particular form of engineering process control. If a known input variable zt can be measured and appropriate relationships built between the input variable, a compensatory variable xt, and the desired output yt, then a feedforward control system can be developed. Using feedforward control, we show under both sudden jump shifts and trends in the mean of the input and compensatory variables that the use of statistical process monitoring tools, such as the exponentially‐weighted moving average and the cumulative sum (CUSUM), significantly reduces variability in both the output variable and the controller relative to the use of feedforward control alone. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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This paper provides a survey of the main advanced control techniques currently adopted in factory automation. In particular, it focuses on five classes of control approaches, namely: model-based control, control based on computational intelligence, adaptive control, discrete event systems-based control and finally event-triggered and self-triggered control. A particular focus is put on the most significant and recent contributions in these areas with attention to their application in the factory automation domain. Finally, open issues, challenges and the requirements of further research efforts for each class are pointed out. 相似文献
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In this paper, we describe the development of the variable dimension and variable sample size T2 control chart (VSSVDT2), which is an enhancement of the variable dimension T2 chart (VDT2). In the VDT2 control chart, the number of variables that are measured to compute the T2 statistic is made variable. Some of the variables are easy or inexpensive to measure and are always monitored. The variables that are more difficult or expensive to measure are measured only when the T2 value from the previous sample exceeds a specified threshold. The VDT2 control chart performs well for moderate and large shifts in the mean vector. However, its performance for small shifts is poor. To improve the chart’s performance in detecting such shifts, we propose the application of the variable sample size technique to the VDT2 control chart, resulting in the VSSVDT2 control chart. To promote the use of the VSSVDT2 chart, a user-friendly software has been developed, which the final user can use to find the best parameters of the VSSVDT2 chart for a particular process. 相似文献
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自适应前馈振动主动控制的参数选择与稳定性 总被引:2,自引:2,他引:2
基于自适应滤波的自适应前馈振动主动控制系统的等效传递函数,对控制系统的参数选择及稳定性进行研究。将受控结构模型变换到Z域,推导控制系统的等效Z域传递函数,把朱利(Jury)稳定判据引入控制系统的稳定性研究,探讨采样频率、滤波器阶数、参考信号等对系统稳定性的影响,得出了具有指导意义的结论 相似文献
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The idea of a variable sampling interval with sampling at fixed times (VSIFT) has been presented by Reynolds. This paper extends this idea to the other two adaptive ―X charts: the variable sampling rate with sampling at fixed times (VSRFT) ―X chart and the variable parameters with sampling at fixed times (VPFT) ―X chart. The VSIFT, VSRFT and VPFT ―X charts are inclusively called the adaptive with sampling at fixed times (AFT) ―X charts in this paper. The control scheme and the design issue are described and discussed for each of the AFT ―X charts. A comparative study shows that the AFT ―X charts have almost the same detection ability as the traditional adaptive ―X charts. However, from the practical viewpoint, the AFT ―X charts are considered to be more convenient to administer than the traditional adaptive ―X charts. Overall, this paper advances the application of ‘sampling at fixed times’ to the adaptive ―X control charts. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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变风量空调系统控制方法及试验台搭建 总被引:2,自引:0,他引:2
介绍了变风量(VAV)空调系统的特点,分析了VAV系统末端控制、AHU等控制方法,着重对末端控制方法与AHU控制方法进行了多种形式的比较,并以实际工程实例加以说明. 相似文献