Results 41 to 50 of about 21,183 (172)
The Research and Design of Coil Tuning Module in MRI [PDF]
, 2016 在成像过程中，射频线圈的工作状态对成像质量影响很大。射频线圈的共振频率和阻抗随着样品的放入会发生改变，造成信噪比和Q值的下降影响成像的质量，而产生的信号反射严重时会损坏功率模块，所以每次成像前后都需对射频线圈进行调谐。传统的调谐采用的是手动操作、上位机显示的方法，操作不便捷，速度较慢。设计一个便于观察的手动调谐检测装置是一个改进的方案，而使用自动调谐不仅不需要人的参与，而且对调谐速度和精度都有一个大的提升。 本文首先回顾了核磁共振的历史和发展，对核磁共振现象及磁共振成像机理进行了阐述 ...
戴奇成
core
Basic income trials and the politics of scale: A research agenda
Policy Studies Journal, EarlyView.Abstract The growing popularity of basic income has led to extensive trials of the policy in numerous settings across the world. However, analysis of the politics of basic income, and in particular the political dynamics preceding and resulting from trial programs, lags. In response, we propose a research agenda that uses political scale to investigate
Jurgen De Wispelaere +2 more
wiley +1 more source
Dianci bileiqi对电气设备地震动响应分析应用较多的主要有两种方法——振型分解反应谱法和动力时程法，其中某些关键动力参数的取值在电气设备抗震相关规范中并没有具体规定，实际分析时往往凭个人经验，致使分析结果因人而异、不尽准确。为了在计算分析阶段通过对关键动力参数准确取值，尽可能真实获取结构动力响应，本研究以特高压支柱式电气设备颇具代表性的两种材质的结构本体及加装减隔震装置后的结构为分析对象，在非线性时程分析方面，通过对动力时程法主要参数：振型参与阶数、地震波及峰值加速度的影响对比分析 ...
陈忆前, 潘飞, 彭伟, 刘洋
doaj +2 more sources
Gaoya dianqi, 2016 准确辨识超级电容器特征参数值是分析超级电容器电气特性和估计其健康状态的重要研究基础。为克服采用阻抗谱分析法辨识特征参数所需激励信号幅值过小,且不能反映研究对象真实工况以及难以实现在线辨识特征参数的缺点,文中采用递推最小二乘法解决此问题。基于实验分析结果发现直接采用该算法辨识出的参数值与真实值差异较大,因此在深入分析辨识算法的基础上,对最小二乘法的辨识结构加以改进。实验和仿真分析结果表明,基于改进后的最小二乘法辨识得到的超级电容器特征参数值更加准确和可信。
赵洋, 孙家南, 姜鸣
doaj
Research and Design of High Isolation multipolarization MIMO Antennas [PDF]
, 2015 无线通信行业的蓬勃发展带来了频谱资源的日趋短缺，在现有的频谱资源上提高通信系统的传输速率和传输质量成为通信领域的研究重点。MIMO（Multiple-InputMultiple-Output，多入多出）可以在不增加发射功率和传输带宽的前提下，显著地提高系统的信道容量和频谱利用率，MIMO技术被认为是新一代无线通信系统中的革命性技术。当前，天线问题是限制MIMO技术发展的最大障碍之一。 本文在介绍MIMO天线的研究背景和意义，以及综述近年来国内外MIMO天线发展现状的基础上 ...
张斌
core
Scientists in power plays: How substantive were scientists' narratives during the COVID‐19 pandemic?
Policy Studies Journal, EarlyView.Abstract Scientists who provide expert advice must engage with policy processes. Little is known about whether and how scientists deal with the political dynamics of policy processes that are inherent to policymaking. We study this question by building on the policy dimension concept within the Narrative Policy Framework.
Jule Ksinsik, Caroline Schlaufer
wiley +1 more source
Gaoya dianqi, 2017 电网的发展对高压开关产品的可靠性提出更高的要求。SF6气体泄漏是导致高压开关缺陷和故障最重要的因素之一,以某省110 kV断路器SF6气体泄漏运行数据为基础,研究了高压开关产品的可靠性数据分析方法。对运行数据的统计分析结果表明,SF6气体泄漏数据能够用威布尔分布模型进行分析描述。进一步对威布尔分布的参数进行了参数估计,并将参数估计结果与统计直方图进行对比,证明了参数估计结果的有效性。基于此,最后对高压开关产品SF6气体泄漏的寿命情况进行了分析,并给出了针对高压开关产品密封结构的基本运维策略。
刘宇 +6 more
doaj
Coalition Opportunity Structures and Advocacy Coordination in Consensus and Majoritarian Democracies
Policy Studies Journal, EarlyView.ABSTRACT Research on advocacy coalitions suggests that belief homophily—the tendency of actors to coordinate based on shared policy beliefs—drives coalition formation. However, coalition opportunity structures, which are shaped by institutional contexts, may influence the extent to which belief homophily matters.
Keiichi Satoh +7 more
wiley +1 more source
Study on Dispensing Technology and Equipment Development for Large LCD Manufacture [PDF]
, 2016 液晶显示器（LiquidCrystalDisplay，简称LCD）涂胶工艺（Dispensing）是其在生产过程中的关键工艺流程之一。此工艺的主要目的是在液晶显示器面板裸露的电极线路上涂布胶状物质，大幅提高电极的耐腐蚀性，保护线路不受环境水分和灰尘的影响，提升产品良品率。随着液晶显示技术向大面积、窄边框、无边框、曲面、超高清等技术发展，其对涂胶工艺提出了更高的要求和挑战。本文对涂胶工艺的关键参数进行研究，并开发了一套新型接触式涂胶设备，以期提高大面积涂胶工艺质量。本文的主要内容如下： （1 ...
翁剑民
core
Policy Studies Journal, EarlyView.ABSTRACT Despite extensive research on policy diffusion, the ways in which policy attention influences this process remain underexplored. This study addressed this gap by distinguishing between three types of policy attention—political speeches, policy issuance and field visits—and investigating their differential impacts when delivered by central and ...
Xiangning Chen, Yahua Wang
wiley +1 more source