INTERFERENCE BETWEEN GRAVITY WELLS STEADY STATE FLOW1

Under steady state conditions of flow, the seepage toward a single gravity well is governed by the Laplace Equation which may be written in terms of either the hydraulic head, the pressure head or the velocity potential. Although this equation is linear, the principle of superposition cannot be applied to sum up the individual effects in the case of a multiple gravity well system due to the variation of the flow domain under the effect of one or several wells. A method is presented allowing the use of the superposition principle in a restricted form. The superposition of the decrements of the base pressure heads than the initial heads before pumping is valid. Also the decrements in the areas of the pressure head diagrams across specific vertical sections than the original areas can be summed up together.     

Limitations in the SAR Use

Summary The paper discusses several aspects of the practical application of the SAR. It is shown that the unit is an ideal solution for basic research and laboratory experiments. SAR is directly nonmeasurable unit. Although methods and devices based upon indirect SAR measurements may widen our knowledge about EM energy distribution and absorption within a body. It is shown that for practical applications the temperature SAR measurement methods are not sensitive enough while methods based upon E(H) measurement are less accurate than traditional approaches. As a result of assumption SAR = 4 W/kg as a basic restriction the present protection standards are illogical and nonrealiazable. A return to traditional units (E, H, S) in the standards and surveying metrology is suggested.     

工业控制系统的雷电灾害防护技术研究

以ICGS雷电冲击试验平台为例介绍了工业控制系统的典型结构,根据其结构的电气特点及雷电造成危害的可能途径,对工业控制系统的雷电防护提出全面具体的技术措施,从而保证工业控制系统正常安全的运行,免受电磁脉冲干扰的危害。经研究,对工业控制系统的防雷保护不仅要做好接闪器,引下线,接地体等基本的外部防护,还要做好等电位联结,屏蔽,信号系统和电源系统的电涌保护等相关内部防雷措施。     

电磁环境污染特点与管理对策

阐述了电磁环境污染的特点及其危害,介绍了我国电磁环境保护标准并与国际非电离辐射防护委员会(ICNIRP)推荐标准进行了比较,提出我国在电磁辐射污染的管理和政策制定中应当考虑的原则.     

闽、浙两省变电所外空间工频电磁污染分布研究

以闽、浙两省110 kV以上等级变电所的电磁场监测结果为基础,着重研究了各电压等级变电所边界处及边界外的空间工频电磁场场强分布规律,分析和探讨了变电所外空间电磁污染的现状,为进一步开展变电所的电磁环境影响研究提出了建设性意见.     

人工电磁辐射源固有危险性指数法评价研究

在总结现有安全评价方法基础上,结合电磁辐射中对污染危害有影响的因素建立了电磁辐射源固有危险性评价的指数法评判模型.在该模型里,就电磁辐射源固有危险性评判的评价指标与等级选取、评价指标标准以及权重确定等进行了研究.     

手机电磁辐射安全评价

综述了手机辐射的原理、辐射危害、辐射场计算和辐射评价技术标准及其检测仪器,并提出了一些减小手机辐射的措施和建议.     

消除DPD法测定水中臭氧浓度干扰因素的研究

研究了Ｈ_２Ｏ_２和其它氧化剂（以过氧化苯甲酰为例）对ＤＰＤ法测定水中臭氧浓度的干扰作用，结果表明，随着ＫＩ浓度或显色时间的增加，Ｈ_２Ｏ_２和其它氧化剂的干扰作用增加，当ＫＩ浓度为０．５ｇ／Ｌ时，可以基本消除这些干扰作用，且当臭氧浓度低于０．６ｍｇ／Ｌ时，不影响臭氧对ＤＰＤ的显色作用。     

认识电磁辐射 畅享绿色生活

电磁辐射是能量以电磁波的形式在空间传播方式,人类赖以生存的地球本身就是一个巨大的电磁场环境,由于人工电磁辐射源的应用,使得电磁场环境趋于复杂化,但只有超过国家规定的电磁环境质量标准时,才称为电磁环境污染.近来,电磁环境信访投诉事件剧增,人们需正确认识电磁辐射,才能安心工作和生活,电磁类建设项目才能更好地服务人们,才能更高效地促进社会发展.     

基于SAE-ARP958环天线校准技术研究

目的介绍基于SAE-ARP958环天线校准技术,研究提高该校准精确性的方法,为精确监测电磁环境提供保障。方法研制一套基于SAE-ARP958环天线的校准装置,提出采用直径分别为30,10,4 cm的三个发射环天线作为磁场发生装置的校准方案,并利用对比测试的方法对校准方案进行优化。结果优化后的校准方案能够实现环天线的精确校准。结论基于SAE-ARP958环天线校准方法具有不受待校环尺寸限制的优点,而且精确性高,值得向具有较多不同尺寸的环天线用户推广。