Understanding the exploration–exploitation dilemma: An fMRI study of attention control and decision‐making performance

This paper studies the cognitive processes that enable decision makers to switch between exploitation and exploration. We use functional magnetic resonance imaging (fMRI) in a sample of expert decision makers to make two main contributions. First, we identify and contrast the specific brain regions and cognitive processes associated with exploitation and exploration decisions. Exploitation activates regions associated with reward seeking, which track and evaluate the value of current choices, while exploration relies on regions associated with attentional control, tracking the value of alternative choices. Second, we propose and test the idea that stronger activation of the brain circuits related to attentional control allows individuals to achieve better decision‐making performance as a result. We discuss the implications of these results for strategic management research and practice. Copyright © 2013 John Wiley & Sons, Ltd     

电子电气电路的隔离技术浅探

文章探讨了电气隔离的两类主要技术即光隔离或磁隔离应用。对于光隔离主要谈了光电耦合器技术应用;对于磁隔离主要谈了变压器应用。     

压控器件的磁隔离驱动电路设计

根据压控器件的特点，设计出了适用于任意占空比的磁隔离驱动电路。通过仿真，进一步得到最优化的实际驱动电路，最后给出了实验波形。     

有限长铁芯实心转子感应电机的运算电抗

本文在考虑铁心有效长度的情况下,以实心转子感应电机的简化模型为基础,推出了这种电机运算电抗的表达式。     

“输血”还是“抽血”?——对北京新城轨道交通建设的一些思考

为了促进北京周边新城建设,疏解中心城的城市功能,北京新城轨道交通建设已经进入了加速期。随着保四争六计划的提出,新城轨道交通线路的建设模式成为讨论的焦点。一些建设单位借鉴国外经验,提出了轨道+物业综合发展的建设模式。但这种模式是否适合北京?笔者对这一问题进行了深入探讨。     

应用于复杂电磁环境下的一种新型船艇导航系统

复杂的电磁环境是未来信息化战场最突出的特征,这样的环境将会干扰现有依靠无 线电波进行工作的导航系统。为有效解决船艇在复杂电磁环境下的导航问题,提出了一种以 陆标定位为基础的新型船艇导航系统。系统通过高清度摄像机和磁航向传感器获取观测物标 数据,经过计算机解算,将位置信息显示到电子海图上。海上试验情况表明,与传统的陆标 定位相比,本系统在定位时间、定位精度等方面具有明显的优越性,完全满足军事航海的要 求,具有良好的军事效益。     

磁性材料基本特性的研究——磁化曲线的实验

磁化曲线研究是大学物理实验中一个比较重要的实验,它主要研究磁化的的特性,通过实睑手段测量相关的物理参量。可以通过剖析阐明此实验建立的思路以及如何测量磁性材料相关的物理量。     

降低单相异步电动机振动噪声新方法的研究

从气隙磁场磁势分布情况可知,单相异步电动机的振动转矩客观存在.为了能更好地降低其振动转矩,提出了把两台参数相同的单相异步电动机采用同轴连接运行的方法.当两台电机定子磁场互差90°电角度时,由椭圆磁场产生的振动转矩将基本被相互抵消.实验证明,该方法能有效降低单相异步电动机的转动转矩.     

Is the Risk Comparison Made by the Public Between EMF and Smoking or Asbestos a Valid One?

The possibility of adverse health effects from exposure to extremely low frequency (ELF) electric and magnetic fields (EMF) has caused considerable controversy in the scientific community and has received great attention in the media and among the general public with many comparing ELF EMF with tobacco smoking and asbestos. Although both smoking and asbestos are now classified by the International Agency for Research on Cancer (IARC) as Group 1 or “established” carcinogens, this was not always the case. In this paper the evidence for the carcinogenicity of ELF EMF is compared with that for smoking and asbestos using the Bradford Hill model for establishing causality between exposure and disease. Application of the model shows that present data are insufficient to demonstrate that exposure to ELF EMF poses a definite human health hazard. However, while the bulk of the evidence is weak, there are several epidemiological studies which have reported an association between prolonged exposure to magnetic fields at levels above what is normally encountered and an increased risk in childhood leukaemia. On this basis IARC has classified ELF magnetic fields as a Group 2B or “possible” carcinogen.     

野马泉地区那陵郭勒河东矿区磁法异常找矿的检查与验证

柴达木综合地质大队2004年度对野马泉地区那陵郭勒河东矿区的Za104磁异常用高精度磁法测量进行了检查,对此异常进行了定性定量解释,提出了验证建议,经钻探验证,见矿情况与物探推断基本一致,取得了较好的找矿效果。在野马泉天下一带以往物探工作中发现了众多磁法异常,有一小部分异常已检查验证为矿致异常,该区尚有大量的磁法异常尚未检查验证,建议对该区磁法异常进行检查验证,可能对该区找矿突破具有重要意义。