Powerline Frequency Electric and Magnetic Fields: A Pilot Study of Risk Perception

The perception of the potential risk arising from human exposure to 50/60 Hz electric and magnetic fields was studied with a quasi-random sample of 116 well-educated, opinion leaders using the risk perception framework previously developed by Slovic, Fischhoff, and Lichtenstein. These individuals rated exposure to fields from transmission lines and electric blankets on a variety of scales that have been found useful in characterizing people's risk attitudes and perceptions. These judgments allowed us to conjecture about the likely desire for regulation of these potential hazards and the likely response to a publicized problem (e.g., an accident or ominous research finding) involving these two sources of exposure. Various forms of detailed information about 50/60 Hz fields were supplied to respondents. The provision of information produced modest, but statistically significant, changes in perceptions in the direction of greater concern about the risks. In response to questions of public policy, participants desired modest regulatory control of field exposure from transmission lines and little or no control of field exposure from appliances like electric blankets.     

VTR走带系统的齐次坐标变换

提出了一种分析磁带录像机(VTR)螺旋扫描走带系统设计参数、坐标计算及描述误差传递的数学方法.这种方法系统性强并有利于编程计算,已应用于本校录像系统生产技术研究院机电一体化研究室的研究工作,是空间复杂问题分析的一种有效方法.     

磁粉温度稳定性测量装置及测量方法

我们利用冲击差值补偿法,建立了一台测量磁粉温度稳定性的装置.该装置的灵敏度为2.1×10~4/mm,测量重复性为8×10~5.我们使用该装置测量了γ-Fe_2O_3等几种磁粉在使用温度范围附近的可逆和不可逆变化.包钴和掺钴的γ-Fe_2O_3磁粉的变化规律与报道的相符.对于普通的γ-Fe_2O_3,当温度从20℃上外到80℃时,剩余磁感应强度 Br 减少了5%;在这个温度范围内经五次循环以后,剩余磁感应强度随温度的变化是可逆的,其温度系数-5×10~4/℃.     

磁调制式直流放大器的静态性能分析

介绍了磁调制式直流放大器的构成,围绕提高磁调制器的性能进行了讨论,给出调制器的灵敏度与其结构尺寸及信号绕组匝数之间的关系,并确定了获得最高灵敏度应满足的条件。根据减小噪声和漂移、提高灵敏度的要求,分析了磁调制器铁芯应采用的结构型式。     

非晶CoZrNb磁性薄膜的研究

研究溅射条件和旋转磁场热处理对CoZrNb薄膜结构和性能的影响。结果表明 ,高的溅射功率和合适的氩气压强对非晶CoZrNb薄膜的形成有用 ,并且这些薄膜的矫顽力较小。旋转磁场热处理将改善薄膜的软磁性能 ,使得矫顽力进一步减小。对溅射条件对薄膜性能的影响机制和旋转磁场热处理改善薄膜性能的机制作了简要的讨论     

DM——Q_2型数字式冲击电流计测定螺线管磁场

针对DM———Q2型数字式冲击电流计无法直接测定冲击常数K值这一问题,改进了计算公式的推导和测量方法,使测量方法更加便捷,结果更加精确。     

量子阱中极化子的电磁场效应

本文应用larsen的算符代数方法,结合变分波函数，研究电磁对量子阱中极化子的影响，给出系统基态能量与阱宽和电磁场的关系。对GaAs/AlAs量子阱作了数值计算。结果显示，电场和磁场都使界面光学模对极化子自能的贡献增大，但电场使体光学声子模的贡献减小。     

Developing Policy in the Face of Scientific Uncertainty: Interpreting 0.3 μT or 0.4 μT Cutpoints from EMF Epidemiologic Studies

There has been considerable scientific effort to understand the potential link between exposures to power-frequency electric and magnetic fields (EMF) and the occurrence of cancer and other diseases. The combination of widespread exposures, established biological effects from acute, high-level exposures, and the possibility of leukemia in children from low-level, chronic exposures has made it both necessary and difficult to develop consistent public health policies. In this article we review the basis of both numeric standards and precautionary-based approaches. While we believe that policies regarding EMF should indeed be precautionary, this does not require or imply adoption of numeric exposure standards. We argue that cutpoints from epidemiologic studies, which are arbitrarily chosen, should not be used as the basis for making exposure limits due to a number of uncertainties. Establishment of arbitrary numeric exposure limits undermines the value of both the science-based numeric EMF exposure standards for acute exposures and precautionary approaches. The World Health Organization's draft Precautionary Framework provides guidance for establishing appropriate public health policies for power-frequency EMF.     

任意偏置磁场中微波静磁波传播特性

研究了任意倾斜的直流偏置磁场作用下磁光薄膜中激发的微波静磁波传播规律,为下一步分析基于静磁波的磁光Bragg器件衍射性能提供基础。计算了YIG薄膜中传播的静磁正向体波特性,结果表明:在倾斜偏置磁场中沿不同方向激发的静磁波具有不同的辐射阻抗,这与垂直磁化情形明显不同;适当倾斜偏置磁场可降低静磁波的插入损耗,从而可增强静磁波对导波光的衍射效应。