主磁场

根据第8代IGRF模型，计算并分析了1900～2000年地球主磁场和分量X、Y、Z的空间功率谱的变化特征。

The spatial power spectrum of the geomagnetic main field and components X ? Y ? Z was studied using the eighth generation of International Geomagnetic Field .

利用BJ模型和国际地磁参考场（IGRF）模型资料，研究了地球主磁场的周期特点。

Based on the data of the Bloxham & Jackson Geomagnetic model ( BJ for short ) and the International Geomagnetic Reference Field ( IGRF ), the features of the geomagnetic main field periodicity are discussed .

地球主磁场B和它的长期变化.B都起源于地球外核的磁流体发电机过程，但是，它们的空间结构和时间演化特征却有很大差异。

The main geomagnetic field , B , and its secular variation ,, originate from same dynamo process in the outer core .

我们采用的控制方案为运用SPWM交直交变频技术实现负载线圈所需的VVVF电源（产生主磁场）；

VVVF power which the load coil needed is produced by SPWM frequency conversion .

研制了一个用于4mm回旋管的超导磁体，它的主磁场达到3T。

A superconducting magnet for gyrotron with 4mm wave length is developed , its main magnetic field reaches 3T .

实现了MIT反投影算法，提出了沿主磁场的直线距离加权法，对不同位置不同电导率的目标进行了仿真成像，结果验证了算法的适用性；

Realized the back-projection algorithm of MIT . We put forward the weighed method in a straight line along the main magnetic field . The algorithm was proved to be applicable by the images of modeled object with different conductivity in various position .

利用自制的微成象系统，在7T的主磁场下，测量了模型样品的核磁共振图象中磁化率引起的失真。

Using a home made microimage system , we studied the susceptibility effect in magnetic resonance image of a model sample under 7 T main field .

结果：体外实验发现仅1枚最小铁屑（0.2mm×0.2mm×0.1mm）未见移动，其他8枚均见异物向主磁场方向移动。

The in vivo study showed that 8 of 9 iron particles moved toward the direction of the main magnetic field , while only one tiny particle ( 0.2 mm × 0.2 mm × 0.1 mm ) had no movement .

IGRF（国际地磁参考场）是有关地球主磁场与长期变化的模型，IGRF的误差主要来源于：忽略外源场、球谐级数的截断、台站分布的不均匀、测量、忽略地壳磁异常场等。

IGRF ( International Geomagnetic Reference Field ) are the models of geomagnetic main field and secular variation . The IGRF errors are from neglecting external field , truncation level of the spherical harmonic series , observatory distribution , measurement , and neglecting the crust geomagnetic anomalies .

地球主磁场空间功率谱的变化特征

The change characteristics of the spatial power spectrum of geomagnetic main field

1900&2000年地球主磁场的本征模分析

Eigen mode analysis of earth 's main magnetic field

地球主磁场的能量密度谱及其长期变化

The energy density spectrum and secular variation of the Earth 's main magnetic Field

地球主磁场的周期性特征

Research on the geomagnetic main field periodicity

主磁场和扫描场线圈固定在同一轭铁架上。

The main magnet and the scan magnet coils were fixed on an iron frame .

主磁场饱和对电压源逆变器&感应电动机传动系统稳定性的影响

Main-Flux Saturation Effect on the Stability Analysis of a Voltage Source Inverter & Induction Motor Drive

但是，高阶项对主磁场的长期变化却有重大影响。

However , the high-degree harmonics have significant contribution to secular variations of the magnetic field .

在逆转期间，主磁场减弱，几乎为零，然后以相反的磁极重新出现。

During a reversal , the main field weakens , almost vanishes , then reappears with opposite polarity .

本文介绍了一个计及气隙主磁场饱和效应的感应电机的计算机仿真模型。

A computer model of a saturated Induction machine is introduced which takes into account the effect of main-flux saturation .

梯度控制系统是在计算机的控制下，为系统提供线性度满足要求的、可快速开关的梯度场，以便动态地修改主磁场，实现成像体素的空间定位。

Gradient control system controlled by the computer provides a gradient field that can be switched quickly and has well linearity .

19901991年中国地区主磁场变化全国地磁台站资料质量分析结果

The variation of main geomagnetic field in China for 1990-1991 The results of the analysing data quality for the geomagnetic observatories in China

它的温度场稳定性直接影响主磁场的稳定性，从而对生成的图象质量有重要影响，因此需要对主磁体温度场进行控制。

Its stability of main magnet field is directly influenced by the stability of temperature , which is influential to the quality of image .

为了提取地壳异常场，必须从观测资料中消除主磁场、磁层场，感应场和电离层场。

In order to get the crustal anomaly field , the main field , magnetospheric , ionospheric and induction fields from the Magsat data must be subtracted .

为了获得位置信息以描绘出质子的空间分布图像，又利用通电线圈在主磁场的基础上叠加了三个梯度场。

In order to obtain the location information and depict a spatial distribution image of the proton , it needs three additional gradient magnetic field generated by the gradient coils .

从全球磁场减去地核主磁场和变化磁场及其感应磁场后，就得到岩石圈磁场，又称地壳磁场，或地磁异常。

The crust magnetic field , or lithospheric magnetic field , can be deduced by subtracting the main field , variation field and its induced counterpart from the total field .

本文给出了在轨道修正情况下的等时场计算方法和结果，其等时性精度好于4×10~（-5）（每圈相移），它是加速器主磁场垫补的依据；

The calculating method and results of the isochronous field with the orbit correction are given , with the isochronous accuracy of 4 × 10 ~ ( - 5 ) or less ( the phase-shift per turn ) . The phase-shift equation is derived .

通过比较相同时间间隔内的导航回波信号的相位，计算出因主磁场漂移引起的共振频率变化，再用频率变化信息对成像序列中的二项式组合激发脉冲的初始相位进行校正。

By comparing the phases of navigator signals acquired in the same time interval , phase differences are obtained , with which the variation of resonance frequency caused by field drift will be calculated . Initial phase of binominal combination pulse is corrected by this variation during scanning .

论文在详细调研国内外加速器主磁铁磁场测量现状基础上，根据物理设计上提出的测磁精度要求，采用SolidWorks软件对CYCHU-10的磁场测量装置进行了虚拟设计和装配。

We used SolidWorks to design and assemble it in virtual environment , which based on a detailed investigation in main magnet field measurement of cyclotron and the status of the physical design on measurement accuracy requirement .

干涉图照片还表明，在45至80mTorr氘气压范围内，等离子体在主压缩磁场的第一个半周期内基本上都是稳定的。

The interferograms also showed that the plasma is essentially stable during the first half-cycle of the main compressive magnetic field in the range 45-80 m Torr deuterium pressures .

SSC超导主二极磁体的磁场测量

Magnetic Field Measurements of SSC Collider Dipole Magnet

舰船主甲板模型感应磁场计算中等效磁化率的应用

Application of Equivalent Susceptibility in the Computation of Inductive Magnetic Field of the Main Deck Model of a Vessel