紫外光/电子束(UV/EB)固化的应用现状与发展前景(七)

6.4印制电路板(PCB)印制电路板简称PCB(Printed Circuit Board),是组装电子零件用的基板,在绝缘基材表面或内部,按预定设计形式从点到点互联线路以及印制元件的成品板。印制电路板包括刚性、挠性和刚挠结合的单面、双面和多层印刷板。用刚性基材制成的印制板称为刚性印制板。用     

纳秒脉冲激光剥离印制电路板三防漆试验研究

采用纳秒脉冲激光对印制电路板表面的有机硅树脂三防漆进行清洗,考察了不同激光能量密度与激光脉冲宽度对印制电路板表面有机硅树脂的剥离效果。当输入的激光能量密度较低且激光脉冲宽度较大时,有机硅树脂发生局部热解,在与印制电路板接触的界面产生气化现象,使有机硅树脂涂层发生膨胀。随着激光能量密度的增大,有机硅树脂部分结构发生降解,有机硅树脂涂层形成鳞状裂纹。当激光能量密度为11.19 J/cm²且激光脉冲宽度为120 ns时,有机硅树脂处于由膨胀向裂解转变的临界状态,此时能够更轻易地从印制电路板表面剥离三防漆,并且对印制电路板基材无明显损伤。     

美国印制电路板用化学品市场概况

通讯产品、计算机及消费性电子产品市场需求的持续增长,将带动全球印制电路板市场的发展。根据BPA Consultant公司的预测,1995～2000年全球印制电路板市场的年均增长率将为6.8％。其中,美国2001年印制电路板的产值将为110亿美元,其印制电路板生产用化学品的市场需求将达到12亿美元。     

如何提高电子设备的可靠性

可靠性是指设备在规定时间内和规定条件下,完成规定的功能的能力。在满足设备各项技术指标的前提下,设计者要保证设备的可靠性。设计印制电路板的时候,要采用正确的方法,包括考虑布线、干扰、温升等问题。     

印制电路板污水处理及铜回收新技术

印制电路板生产过程中的废水，其中大量的是铜，极少量的有铅、锡、金、银、氟、氨、有机物和有机络合物等，因此印制电路板污水处理不仅具有环境意义还有资源意义，近来印制电路板污水处理及铜回收出现不少新技术。     

中国电子电路产业基础材料市场发展趋势

电子玻纤布、覆铜板及印制电路板,是电子电路产业链上,三个紧密相连、唇齿相依的上下游基础材料行业。电子玻纤布是覆铜板的主要原材料,覆铜板又是印制电路板的半成品。而印制电路板却是电子电路产业必不可少的基础材料。如果说,集成电路是一级封装.各种电子电路     

广东省印制电路板行业污染现状与治理技术

印制电路板行业的生产工艺复杂,加工过程消耗大量能源,产生多种污染物、物料损耗也多。文章主要介绍了广东省印制电路板行业环境污染的种类以及污染治理技术的应用现状,最后对广东省印制电路板行业污染治理技术发展方向给出总结与建议。     

高散热印制电路板及其应用

该文介绍了高散热印制电路板的特性、一般工艺过程 ,以及与普通印制电路板 (环氧树脂玻璃布基 )的性能比较 ,旨在为印制板上大功率元器件的散热和热匹配问题提供一种解决方案。     

某印制电路板企业清洁生产评价体系构建与探讨

由于《印制电路板制造业清洁生产水平评价技术要求》(征求意见稿)及《清洁生产标准印制电路板制造业》(HJ 450–2008)已废止,导致印制电路板(PCB)制造业清洁生产审核过程中缺少判定清洁生产水平的依据,因此无法判定企业的清洁生产水平,不能满足《清洁生产审核评估与验收指南》的要求。为此,依据《清洁生产评价指标体系编制通则》(试行稿),结合《江西强达电路科技有限公司清洁生产审核报告》,构建了某印制电路板企业的评价指标体系,为企业的清洁生产水平评价提供了基础依据,同时为印制电路板行业清洁生产水平评价提供参考。     

脉冲电源在印制电路板镀铜上的应用

对印制电路板镀铜的关键性进行了论述，传统的硅整流、可控硅电源很难满足当今电子工业表面贴装所要求的印制电路板加密导线、缩小孔径、增加层次的需求。脉冲电源以其优越的性能通过了工艺试验与性能考核并获得了成功，为提高印制电路板的可靠性提供了良好的保障。     

基于自抗扰控制器的直流双闭环调速系统

一种新型的直流调速系统,速度环采用自抗扰控制器,该控制器对系统的内部扰动和外部扰动进行观测,并加以补偿。仿真结果表明,采用自抗扰控制器具有较好的动态性能、鲁棒性和无超调。该技术广泛应用于化工厂机泵系统中。     

对水泥厂变频系统电磁兼容性问题的探讨

变频器因其优良的性能和功能在水泥企业应用很广,但使用中易受其它电气设备干扰。同时,因变频器的非线性负载特性,运行中会产生大量谐波而干扰其他设备。因此确保变频器具有良好的电磁兼容性非常重要,其关键是控制好谐波量。文章分析了各类变频器的谐波干扰差异;详细探讨了抑制和治理变频器谐波的有效措施——低谐波技术和滤波措施。同时,简要介绍了水泥厂变频器系统的抗干扰技术措施。     

整流装置滤除谐波的措施

对多相整流电路的高次谐波进行了分析，并指出其对节能工作及微机的集散系统的干扰，经过分析提出了消除谐波的措施，通过应用实例介绍了不同条件时可采取的不同消除办法。     

Modified dynamic matrix control

DMC (Dynamic Matrix Control) has been used successfully in industry for the last decade. It can deal with constraints and unusual dynamic behavior directly. It also shows a good control performance for the servo problem. Relatively, it can’t reject disturbances systematically. We propose a modified DMC method to control the regulatory process more efficiently. The proposed DMC method makes the control output by subtracting the estimated disturbance from the control output of the original DMC. Here, the disturbance is estimated by a new disturbance estimator. It shows better control performances than the original DMC.     

Proportion integral-type active disturbance rejection generalized predictive control for distillation process based on grey wolf optimization parameter tuning

The high-purity distillation column system is strongly nonlinear and coupled, which makes it difficult to control. Active disturbance rejection control (ADRC) has been widely used in distillation systems, but it has limitations in controlling distillation systems with large time delays since ADRC employs ESO and feedback control law to estimate the total disturbance of the system without considering the large time delays. This paper designs a proportion integral-type active disturbance rejection generalized predictive control (PI-ADRGPC) algorithm to control the distillation column system with large time delay. It replaces the PD controller in ADRC with a proportion integral-type generalized predictive control (PI-GPC), thereby improving the performance of control systems with large time delays. Since the proposed controller has many parameters and is difficult to tune, this paper proposes to use the grey wolf optimization (GWO) to tune these parameters, whose structure can also be used by other intelligent optimization algorithms. The performance of GWO tuned PI-ADRGPC is compared with the control performance of GWO tuned ADRC method, multi-verse optimizer (MVO) tuned PI-ADRGPC and MVO tuned ADRC. The simulation results show that the proposed strategy can track reference well and has a good disturbance rejection performance.     

S变换与欧氏距离在电能质量扰动识别中的应用

为了满足电能质量扰动检测与分类的需要、进一步提高电能质量扰动识别效率,提出一种S变换与欧氏距离相结合的电能质量扰动识别方法。对电能质量扰动识别方法进行了仿真分析,结果表明:在信噪比为20d B的情况下,电压暂升、电压暂降和电压闪变的识别率较高,而电压中断、谐波和暂态振荡由于受到谐波和噪声干扰,识别率相对较低;随着信噪比的增加,扰动信号的识别率均随之增加。     

降低总氮测定中浑浊度干扰的经验

根据GB 11894—1989((水和废水标准检验法》中的检测方法检测水源水中的总氮时发现,当水样的浑浊度高时．水样在波长275nm处的干扰值有明显增高现象。通过实验对比显示．消解后设法降低水样的浑浊度,会使空白值下降。     

Performance assessment of MIMO control systems with time-variant disturbance dynamics

In this paper, we consider performance assessment problem for multivariable control systems subject to piecewise constant time varying disturbance dynamics. The problem is motivated by the observation that most industrial controllers are linear time invariant (LTI) but the process, particularly the disturbance dynamics, can be time varying. We consider a class of disturbance dynamics that can be modelled by piecewise linear disturbance models, namely piecewise linear time varying (LTV) disturbance dynamics. The problem is formulated as searching for a multi-input multi-output (MIMO) benchmark control that is LTI but optimal in regulating the LTV disturbances. The single-input single-output (SISO) case has been previously solved by minimizing the variance of a most representative disturbance or by the minimization of the sum of the weighted variances of all but one of major disturbances, while satisfying a structured regulatory performance requirement for the major disturbance. In this paper, the previous results are extended to MIMO systems. The counterparts of the two SISO benchmarks are defined as the regular linear time varying disturbances (LTVDs) benchmark and the weighted LTVD benchmark for MIMO control systems, respectively. In addition, a new yet more practical LTVD benchmark, the generalized LTVD benchmark, is also proposed, which minimizes the maximum total variance among all different disturbance dynamics. These three LTVD benchmarks are compared by simulation and industrial application examples. The results show that the weighted and generalized LTVD benchmarks can always lead to better trade-offs on the total output variances.     

Theoretical Study of a Diesel‐Filled Airtight Structure Unit Subjected to Shaped Charge Jet Impact

Diesel composite armor has high penetration resistance and can be used in tank vehicles to improve their protective capability and increase fuel oil storage. This study provides a theoretical calculation method to investigate the interaction between a shaped charge jet and a diesel‐filled airtight structure unit. Disturbance theory can predict the part of the jet that is disturbed by diesel fuel. The lumen radius for the container was varied to study its influence on the disturbance capability. A great lumen radius is found to cause lower maximum and minimum speeds of the disturbance velocity range of the jet, as well as a narrower disturbance velocity range. The reliability of the theoretical results was validated by experiments, and the experimental data show good agreement with the theoretical results.     

基于综合方法应用的管道泄漏检测研究

分析管道泄漏检测中经常出现的两个问题,对其中一个由于两个站点之间的干扰信号产生时间差,会引起误报警的情况,提出用序贯概率比检验法(SPRT)解决,并用检测延迟的补偿法来弥补SPRT检验法检测延迟的缺点,从而提高系统的检测速度,再用小波变换法进行泄漏定位。两种方法的结合不但可以有效地去除干扰噪声,而且缩短了泄漏检测的响应时间,提高了泄漏定位的精度。实验表明该方法克服了序贯概率比的缺点,具有良好的应用前景。