DDC通讯故障分析

在楼宇自控系统的调试、使用过程中,常常遇到控制系统发生通讯故障,影响系统的正常运行。本文通过介绍通讯电路的工作原理和传输方式等基本特性,分析产生问题的原因,阐述了共模电压影响通讯电路的几种情况;以及如何正确连接通讯设备的终端电阻;从工程角度分析设备内部通讯电路结构与通讯线屏蔽层接地问题;并对实际工程情况产生的部分通讯故障进行了分析。

工艺参数对低压TVS器件耐压的影响

目前低压瞬间电压抑制(TVS)二极管工艺参数的研究还不够深入。从深p型(DP)基区杂质浓度、杂质注入能量及基区尺寸控制三个方面探究了工艺条件对低击穿电压的影响。当DP注入剂量小于6.0×1014cm-2时,pn结以雪崩击穿为主,耐压大于6 V。DP注入能量在50 ke V以下与高浓度n+区复合形成的pn结雪崩击穿耐压大于6 V;当控制基区尺寸使n+集电区与DP基区的间距大于1.2μm时击穿电压保持为7 V,但是随着n+与DP基区的间距增加,电流导通路径受到挤压变窄,在相同的反向测试电流下,器件耐压略有提升。通过对单向TVS工艺仿真优化,选择了关键工艺参数,并进行了工程实验,制备了兼具低电容和高抗ESD能力的TVS器件,保证了对主器件实施可靠的保护。

税控装置抗干扰技术

本文介绍了税控装置主要存在的干扰原因及预防的措施。

THE ROLES OF DETOXIFYING ENZYMES AND AChE INSENSITIVITY IN METHAMIDOPHOS RESISTANCE DEVELOPMENT AND DECLINE IN NILAPARVATA LUGENS

Methamidophos resistance of brown planthopper ( Nilaparvata lugens Stl, BPH) was selected in laboratory. After successive selection for 9 generations, the selection was ceased by rearing BPH without contact with any insecticide for 9 generations. In the full course, the successive changes of esterase activity, MFO activity, GSTs activity and AChE insensitivity were analyzed. The results showed that the change of esterase activity was high correlated with that of methamidophos in the full course, which indicated that esterase played very important role both in the resistance development and in the resistance decline. However, the change of AChE insensitivity only significantly correlated with that of resistance in the development stage, and the change of MFO activity or GSTs activity only significantly correlated with that of the resistance in the decline stage, which indicated the changes of AChE insensitivity, MFO activity or GSTs activity only played some roles in different stages of the resistance change.