期刊文献+
共找到29篇文章
< 1 2 >
每页显示 20 50 100
电感自积分式脉冲点磁场探头的研究 被引量:2
1
作者 李恪 王建国 任海蓉 《电测与仪表》 北大核心 2000年第6期52-54,共3页
详细介绍了一种用于测量空间某点磁场幅值的电感自积分式脉冲磁场探头的工作原理、电路及其标定结果。
关键词 磁场测量 电感自积式 脉冲点磁场探头
下载PDF
SHINE超导波荡器磁场点测量霍尔探头位置标定
2
作者 吴泽州 张继东 +1 位作者 陈金雅 周巧根 《核技术》 CAS CSCD 北大核心 2023年第9期9-16,共8页
正在建设的上海硬X射线自由电子激光装置(Shanghai HIgh repetitioN rate XFEL and Extreme light facility,SHINE)将利用40台周期长度为16 mm、磁长度为4 m、净气隙高度为4 mm的真空内超导波荡器,以产生垂直线极化的自由电子激光。霍... 正在建设的上海硬X射线自由电子激光装置(Shanghai HIgh repetitioN rate XFEL and Extreme light facility,SHINE)将利用40台周期长度为16 mm、磁长度为4 m、净气隙高度为4 mm的真空内超导波荡器,以产生垂直线极化的自由电子激光。霍尔探头磁场测量是目前测量波荡器场图最可靠的测量方法之一,而霍尔探头灵敏中心的定位精度是影响磁场测量精度的主要因素之一。本文介绍了这些超导波荡器的磁场点测量系统,以及霍尔探头灵敏中心的高精度位置标定。通过翻转安装有霍尔探头与角锥棱镜的磁测滑车,可分别标定霍尔探头灵敏中心以及角锥棱镜顶点和磁测滑车翻转轴的横向间距,从而获得霍尔探头灵敏中心彼此之间的横向距离,以及霍尔探头灵敏中心与角锥棱镜顶点之间的横向距离。该方法的标定精度好于±10μm,能满足该超导波荡器磁场测量的要求。 展开更多
关键词 超导波荡器 磁场测量 三维激光定位
下载PDF
基于通用运动控制器的磁场点测台控制系统
3
作者 闫陇刚 邓德荣 +3 位作者 李鹏 王建新 杨兴繁 黎明 《强激光与粒子束》 EI CAS CSCD 北大核心 2018年第12期99-104,共6页
磁场点测台是加速器领域测量磁铁和波荡器等磁元件的主要设备之一,其需要在快速精确的控制系统支持下工作。中国工程物理研究院应用电子学研究所近期搭建了一套磁场点测台,并基于通用运动控制器(UMAC),设计开发了该磁场点测台的控制系... 磁场点测台是加速器领域测量磁铁和波荡器等磁元件的主要设备之一,其需要在快速精确的控制系统支持下工作。中国工程物理研究院应用电子学研究所近期搭建了一套磁场点测台,并基于通用运动控制器(UMAC),设计开发了该磁场点测台的控制系统。系统采用了上位机工控机和下位机UMAC两级计算机控制的层级结构,可以充分发挥其各自优势:下位机UMAC可以快速、精确地控制电机动作,因此下位机程序负责控制六轴运动平台以go-stop模式运动;上位机工控机数据处理和存储能力强,因此上位机人机交互界面负责收集、记录和显示磁场数据,并负责设定磁场测量参数和监控运行状态。两级计算机动作的同时性通过触发信号来保证。 展开更多
关键词 磁场测台 通用运动控制器 控制系统
下载PDF
交变磁场测量的研究进展 被引量:5
4
作者 唐露新 张淏 《测控技术》 CSCD 北大核心 2013年第4期1-4,共4页
通过对磁场的种类和相关测量理论及方法分析,归纳了当前国内外交变磁场测量方法以及测量传感器和仪器的研究现状。针对医疗仪器等行业的需求,指出中频强磁场和空间点磁场测量方面的一些难点和取得的进展,介绍了最新研发的中频强磁场测... 通过对磁场的种类和相关测量理论及方法分析,归纳了当前国内外交变磁场测量方法以及测量传感器和仪器的研究现状。针对医疗仪器等行业的需求,指出中频强磁场和空间点磁场测量方面的一些难点和取得的进展,介绍了最新研发的中频强磁场测量仪。最后分析了磁场测量技术的发展趋势,随着磁场测量应用的范围和各种要求的提高,测量磁场的频率、强度和空间分布变得越来越重要。 展开更多
关键词 磁场分类 磁场测量 电磁兼容 中频强磁场 空间点磁场
下载PDF
交变磁场测量系统中磁传感器的设计 被引量:3
5
作者 张玉华 罗飞路 白奉天 《传感器世界》 2003年第12期6-8,12,共4页
阐述了交变磁场测量(ACFM)系统中磁场传感器的检测原理,并在此基础上,根据被测磁场的变化特点,设计了一种可实现空间“点”磁场测量的传感器。通过对磁场的实际测量结果和理论计算值的比较,说明该传感器能实现对“点”磁场信号的准确测量。
关键词 磁传感器 交变磁场测量系统 磁场 无损检测 检测原理
下载PDF
一种新型磁刺激场测量用传感器 被引量:2
6
作者 冯远明 王明时 +2 位作者 郭仲枢 孙克忱 李国峰 《天津大学学报》 EI CAS CSCD 1998年第5期595-599,共5页
提出了一种用于磁刺激场测量的新型点磁场测量传感器的理论设计.通过对有解析表达式的刺激磁场实际测量和理论计算比较,传感器对点磁场测量误差小于±5%,可用于磁刺激场分布的准确测量.
关键词 磁刺激 磁场分布 点磁场测量 磁敏传感器
下载PDF
磁刺激场中传感器的设计 被引量:1
7
作者 王明时 周凯 《中国临床康复》 CSCD 北大核心 2006年第9期144-146,共3页
目的:设计可用于磁刺激场分布的准确测量的传感器。方法:实验于2005-03/04在天津大学精仪学院电磁屏蔽室内完成,以法拉第电磁感应原理为基础,对直径为1.0mm规格的线圈进行了绕制和磁场的测量、分析。绕制产生磁场的线圈时所用到的工具... 目的:设计可用于磁刺激场分布的准确测量的传感器。方法:实验于2005-03/04在天津大学精仪学院电磁屏蔽室内完成,以法拉第电磁感应原理为基础,对直径为1.0mm规格的线圈进行了绕制和磁场的测量、分析。绕制产生磁场的线圈时所用到的工具和器材包括:漆包线、绕线机、绝缘骨架、绝缘胶条。提出一种用于磁刺激场测量的新型点磁场测量传惑器的设计,并从理论上加以论证。结果:通过对有解析表达式的刺激磁场实际测量和理论计算比较,传感器对点磁场测量误差小于±5%。结论:按照此种方法设计的传感器可用于磁刺激场分布的准确测量。 展开更多
关键词 点磁场 传导测量术
下载PDF
铝电解槽阴极电流分布形象化 被引量:3
8
作者 梁汉 梁诗静 《轻金属》 北大核心 2020年第9期30-37,共8页
铝电解槽寿命与阴极电流分布曲线形状有密切关系。电解槽从焙烧启动开始,到正常运行,再到槽寿命终结,最后到停槽大修,其阴极电流分布曲线形状的变化,能动态地反映槽底破损演变的整个过程。将绘制阴极电流分布曲线和测量铝液含铁量的方... 铝电解槽寿命与阴极电流分布曲线形状有密切关系。电解槽从焙烧启动开始,到正常运行,再到槽寿命终结,最后到停槽大修,其阴极电流分布曲线形状的变化,能动态地反映槽底破损演变的整个过程。将绘制阴极电流分布曲线和测量铝液含铁量的方法相结合,能快速确定槽底破损情况及其破损位置。 展开更多
关键词 曲线形状 寿命 点磁场
下载PDF
Singularity-free expression of magnetic field of cuboid under undulating terrain 被引量:4
9
作者 匡星涛 杨海 +1 位作者 朱晓颖 李伟 《Applied Geophysics》 SCIE CSCD 2016年第2期238-248,416,共12页
Most of the current computing methods used to determine the magnetic field of a uniformly magnetized cuboid assume that the observation point is located in the upper half space without a source. However, such methods ... Most of the current computing methods used to determine the magnetic field of a uniformly magnetized cuboid assume that the observation point is located in the upper half space without a source. However, such methods may generate analytical singularities for conditions of undulating terrain. Based on basic geomagnetic field theories, in this study an improved magnetic field expression is derived using an integration method of variable substitution, and all singularity problems for the entire space without a source are discussed and solved. This integration process is simpler than that of previous methods, and final integral results with a more uniform form. AT at all points in the source-flee space can be calculated without requiring coordinate transformation; thus forward modeling is also simplified. Corresponding model tests indicate that the new magnetic field expression is more correct because there is no analytical singularity and can be used with undulating terrain. 展开更多
关键词 Undulating terrain magnetic field of cuboid variable substitution analytical singularity
下载PDF
基于磁性粒子成像技术的一维建模仿真研究 被引量:2
10
作者 谢迪 张朴 程晶晶 《计算机仿真》 CSCD 北大核心 2013年第9期410-414,共5页
磁性粒子成像(Magnetic Particle Imaging,MPI)是一种新兴的医疗成像方式,对于空间中的磁纳米粒子分布具有极高的灵敏度,同时也克服了电离辐射的影响。MPI能够获得关于磁性粒子的高质量的图像,具有高时空分辨率。为了研究MPI中图像准确... 磁性粒子成像(Magnetic Particle Imaging,MPI)是一种新兴的医疗成像方式,对于空间中的磁纳米粒子分布具有极高的灵敏度,同时也克服了电离辐射的影响。MPI能够获得关于磁性粒子的高质量的图像,具有高时空分辨率。为了研究MPI中图像准确重建的相关问题,首先简要介绍了MPI的成像原理,并根据基本原理建立了一维模型,同时在MATLAB中对模型进行仿真,分析了影响MPI浓度测量精度的三个重要因素及影响方式,仿真结果显示这三种因素对MPI浓度测量精度的影响呈现出一定的规律性,最后从信号处理的角度对上述规律给出合理的解释。仿真试验的分析将对MPI中图像的重建起到了指导作用。 展开更多
关键词 磁性纳米粒子 朗之万顺磁理论 快速傅里叶变换 磁场 空间编码
下载PDF
Linear and Nonlinear Optical Absorptions of a Hydrogenic Donor in a Quantum Dot Under a Magnetic Field 被引量:3
11
作者 XIE Wen-Fang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第5期923-926,共4页
The linear and nonlinear optical properties of a hydrogenic donor in a disc-like parabolic quantum dot in the presence of an external magnetic field are studied. The calculations were performed within the effective ma... The linear and nonlinear optical properties of a hydrogenic donor in a disc-like parabolic quantum dot in the presence of an external magnetic field are studied. The calculations were performed within the effective mass approximation, using the matrix diagonalization method and the compact density-matrix approach. The linear and nonlinear optical absorption coefficients between the ground (L =0) and the first excited state (L = 1) have been examined based on the computed energies and wave functions. We find that the linear, nonlinear third-order, and total optical absorption coefficients are strongly affected by the confinement strength of QDs, the external magnetic field, and the incident optical intensity. 展开更多
关键词 quantum dot nonlinear optics
下载PDF
Significance of induced magnetic field and variable thermal conductivity on stagnation point flow of second grade fluid 被引量:2
12
作者 A.A.KHAN S.ILYAS +1 位作者 T.ABBAS R.ELLAHI 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第11期3381-3390,共10页
In this study,the stagnation point transport of second grade fluid with linear stretching under the effects of variable thermal conductivity is considered.Induced magnetic field impact is also incorporated.The nonline... In this study,the stagnation point transport of second grade fluid with linear stretching under the effects of variable thermal conductivity is considered.Induced magnetic field impact is also incorporated.The nonlinear set of particle differential equations is converted into set of ordinary differential equations through appropriate transformation.The resulting equations are then resolved by optimal homotopy analysis method.The effect of pertinent parameters of interest on skin friction coefficient,temperature,induced magnetic field,velocity and local Nusselt number is inspected by generating appropriate plots.For numerical results,the built-in bvp4 c technique in computational software MATLAB is used for the convergence and residual errors of obtained series solution.It is perceived that the induced magnetic field is intensified by increasing β.It can also be observed that skin friction coefficient enhances with increasing value of magnetic parameter depending on the stretching ratio a/c.For the validness of the obtained results,a comparison has been made and an excellent agreement of current study with existing literature is found. 展开更多
关键词 stagnation point variable thermal conductivity induced magnetic field second grade fluid
下载PDF
Effects of Impurity on the Ground—State Transitions of a Quantum Dot in Strong Magnetic Field 被引量:2
13
作者 K.S.CHAN E.Y.B.PUN 《Communications in Theoretical Physics》 SCIE CAS CSCD 2001年第6期735-739,共5页
The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic valu... The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic values of angular momentum in a magnetic field. We show, in this paper, that the implantation of an impurity ion at the center can either enhance or suppress such transitions, depending on whether it is an acceptor or a donor ion. 展开更多
关键词 impurity states quantum dots
下载PDF
Phase Diagram for Ashkin-Teller Model on Bethe Lattice 被引量:1
14
作者 LEJian-Xin YANGZhan-Ru 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第5期841-846,共6页
Using- the recursion method, we study the phase transitions of theAshkin-Teller model on the Bethe lattice, restricting ourselves to the case of ferromagneticinteractions. The isotropic Ashkin-Teller model and the ani... Using- the recursion method, we study the phase transitions of theAshkin-Teller model on the Bethe lattice, restricting ourselves to the case of ferromagneticinteractions. The isotropic Ashkin-Teller model and the anisotropic one are respectivelyinvestigated, and exact expressions for the free energy and the magnetization are obtained. It canbe found that each of the three varieties of phase diagrams, for the anisotropic Ashkin-Tellermodel, consists of four phases, i.e., the fully disordered paramagnetic phase Para, the fullyordered ferromagnetic phase Ferro, and two partially ordered ferromagnetic phases 【 σ 】 and 【 σs】, while the phase diagram, for the isotropic Ashkin-Teller model, contains three phases, i.e., thefully disordered paramagnetic phase Para, the fully ordered ferromagnetic phase Baxter Phase, andthe partially ordered ferromagnetic phase 【 σs 】. 展开更多
关键词 Ashkin-Teller model bethe lattice phase transition
下载PDF
Effect of the Electron—Phonon Coupling on Barrier D^— Quantum Dots in Magnetic Fields 被引量:2
15
作者 XIEWen-Fang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2002年第1期99-104,共6页
The influence of the electron-phonon coupling on the energy of low-lying states of the barrier D<SUP>-</SUP> center, which consists of a positive ion located on the z-axis at a distance from the two-dimens... The influence of the electron-phonon coupling on the energy of low-lying states of the barrier D<SUP>-</SUP> center, which consists of a positive ion located on the z-axis at a distance from the two-dimensional quantum dot plane and two electrons in the dot plane bound by the ion, is investigated at arbitrary strength of magnetic field by making use of the method of few-body physics. Discontinuous ground-state energy transitions induced by the magnetic field are reported. The dependence of the binding energy of the D<SUP>-</SUP> ground state on the quantum dot radius is obtained. A considerable enhancement of the binding is found for the D<SUP>-</SUP> ground state, which results from the confinement of electrons and electron-phonon coupling. 展开更多
关键词 quantum dot electron-phonon interaction few-body physics
下载PDF
Knotted Topological Phase Singularities of Electromagnetic Field
16
作者 REN Ji-Rong ZHU Tao MO Shu-Fan 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第11期1071-1076,共6页
In this paper,knotted objects (RS vortices) in the theory of topological phase singularity in electromagneticfield have been investigated in details.By using the Duan's topological current theory,we rewrite the to... In this paper,knotted objects (RS vortices) in the theory of topological phase singularity in electromagneticfield have been investigated in details.By using the Duan's topological current theory,we rewrite the topological currentform of RS vortices and use this topological current we reveal that the Hopf invariant of RS vortices is just the sum ofthe linking and self-linking numbers of the knotted RS vortices.Furthermore,the conservation of the Hopf invariant inthe splitting,the mergence and the intersection processes of knotted RS vortices is also discussed. 展开更多
关键词 knotted optical vortex topological current phase singularity
下载PDF
Sensors Array Technique for Monitoring Aluminum Alloy Spot Welding
17
作者 王蕤 罗震 +3 位作者 单平 步贤政 袁书现 敖三三 《Transactions of Tianjin University》 EI CAS 2010年第5期322-327,共6页
In this paper,the sensors array technique is applied to the quality detection of aluminum alloy spot welding.The sensors array has three forms,i.e.,linear magnetic sensors array,annular magnetic sensors array and cros... In this paper,the sensors array technique is applied to the quality detection of aluminum alloy spot welding.The sensors array has three forms,i.e.,linear magnetic sensors array,annular magnetic sensors array and cross magnetic sensors array.An algorithm based on principal component analysis is proposed to extract the signal eigenvalues.The three types of magnetic sensors array are used in the experiment of monitoring the signal.After the eigenvalues are extracted,they are used to build a relationship with ... 展开更多
关键词 spot welding magnetic field sensors array principal component analysis
下载PDF
A Negative Donor D^- in a Magnetic Field
18
作者 LIU Chang XIE Wen-Fang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第6期1117-1120,共4页
Using the method of numerical matrix diagonalization within the effective-mass approximation, we investigated a D^--center quantum dot system subjected to a Gaussian potential confinement. We obtain the dependence of ... Using the method of numerical matrix diagonalization within the effective-mass approximation, we investigated a D^--center quantum dot system subjected to a Gaussian potential confinement. We obtain the dependence of binding energies of the ground-states of the D^--center on the depth of Gaussian potential and the magnetic field strength. The result shows clearly that the binding energies of the ground-states of the D^--center are rather sensitive to the depth of potential and the strength of magnetic field. 展开更多
关键词 D^--center quantum dot Gaussian potential magnetic field
下载PDF
Alternating response of spin current in a magnetic-oscillating quantum dot
19
作者 宋红岩 宋小龙 +2 位作者 张爱芳 吴留坡 施耀铭 《Journal of Shanghai University(English Edition)》 CAS 2007年第6期566-569,共4页
We investigate alternating response of the spin current in a quantum dot system coupled to a normal metal electrode, to which an alternating driving voltage and a pumping rotating magnetic field are applied. The expre... We investigate alternating response of the spin current in a quantum dot system coupled to a normal metal electrode, to which an alternating driving voltage and a pumping rotating magnetic field are applied. The expression of the time-averaged spin current and its differential is obtained based on a non-equilibrium Green's function method. We find that for a given rotating frequency, the spin current increases rapidly and appears to have small steps when the driven frequency increases. As the driven frequency is further increasing, the spin current can be significantly enhanced and approaches a stable value. The photon-assisted processes bring about interesting features of spin current. The influence of the gate voltage and temperature on the spin current is examined in detail. 展开更多
关键词 spin current AC response photon-assisted tunneling.
下载PDF
Binding Energies of D^- Centers Trapped by a Quantum Dot in a Magnetic Field
20
作者 XIE Wen-Fang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第4期748-750,共3页
A investigation of the properties of the bound states of D^- centers confined in a parabolic quantum dot has been performed for the case with the presence of a perpendicular magnetic field. Calculations are carried ou... A investigation of the properties of the bound states of D^- centers confined in a parabolic quantum dot has been performed for the case with the presence of a perpendicular magnetic field. Calculations are carried out by using the method of numerical diagonalization of Hamiltonian matrix within the effective-mass approximation. The binding energies of the ground and some bound-excited states are obtained as a function of the applied magnetic field strength. Detailed calculations of the binding energies for a number of low-lying states show that for field strength less than B = 2.1 T, the D center confined in a quantum dot possesses two bound states, for 2.1 〈 B 〈 2.4 T, there exist three bound states, etc. Further relevant characteristics of the D- center quantum dots in magnetic fields are provided. 展开更多
关键词 quantum dots DONOR
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部