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公开(公告)号：EP0251342A3
公开(公告)日：1988-11-17
申请号：EP87111469
申请日：1984-11-09
CPC分类号： G01R33/421 , G01R33/3815 , G01R33/3875 , Y10S505/879
摘要： A magnet assembly (1) comprises a first superconducting coil assembly (A,Aʹ-C,Cʹ) for generating a first magnetic field; and a second superconducting coil assembly (D-F) for generating a second magnetic field. The second superconducting coil assembly (D-F) is concentric and electrically connected in series with the first superconducting coil assembly, wherein the first and second super conducting coil assemblies each generate, in use, magnetic fields whose corresponding components are of substantially the same order of magnitude. The assemblies are arranged such that a resultant uniform magnetic field is generated in a working volume (3), and the second magnetic field opposes the first magnetic field outwardly of the magnet assembly (1). The first and second coil assemblies are also arranged such that they only generate a uniform magnetic field within the working volume (3) when operated together.
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公开(公告)号：EP0146267A2
公开(公告)日：1985-06-26
申请号：EP84307979.9
申请日：1984-11-16
CPC分类号： H05K9/00
摘要： A magnet system comprises magnetic field generating means such as a superconducting magnet (12) and a shield including a number of sheets (9) of magnetic material, the size (1 z , 1 x ) and position (r) of the or each sheet (9) relatively to the magnetic field generating means (12) being such that in use at the edge of the sheet or sheets the component of magnetisation (M z ) parallel to the sheet in the direction of the magnetic field is less than or substantially equal to zero.
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公开(公告)号：EP1319906A3
公开(公告)日：2003-11-05
申请号：EP02024384.6
申请日：2002-11-04
IPC分类号： F25B9/14
CPC分类号： F25B9/145 , F25B2309/1421
摘要： A pulse tube refrigerator comprises a fixed pressure casing (3) containing cold parts and a removable pressure casing (2) containing serviceable parts. The fixed pressure casing (3) and the removable pressure casing (2) are coupled together via a joining member (1). During cooling operation the joining member (1) is arranged such that refrigerant fluid flows between the fixed and the removable casings. During servicing the joining member is arranged to cut off flow of refrigerant fluid between the fixed and removable casings, such that refrigerant in the fixed casing is trapped and parts in the removable casing are accessible for servicing. After servicing, substantially pure refrigerant fluid is pumped into the removable casing (2), the fixed and removable casings are re-joined and the joining member (1) is arranged such that refrigerant fluid flows between the casings again.
摘要翻译： 脉冲管制冷器包括含有冷部件的固定压力壳体（3）和包含可使用部件的可拆卸压力壳体（2）。 固定压力壳体（3）和可移除的压力壳体（2）通过连接构件（1）联接在一起。 在冷却操作期间，连接构件（1）被布置成使得制冷剂流体在固定和可移除的壳体之间流动。 在维修期间，连接构件被布置成切断固定和可移除壳体之间的制冷剂流体的流动，使得固定壳体中的制冷剂被捕获并且可移除壳体中的部件可接近进行维修。 在维修之后，基本上纯的制冷剂流体被泵送到可移除的壳体（2）中，固定和可移除的壳体被重新接合，并且连接构件（1）被布置成使得制冷剂流体再次在壳体之间流动。
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公开(公告)号：EP1304516A3
公开(公告)日：2003-11-05
申请号：EP02079102.6
申请日：2002-10-02
IPC分类号： F16K11/085 , F25B9/14
CPC分类号： F16K3/188 , F16K11/0743 , F25B9/145 , F25B2309/006 , F25B2309/14181
摘要： A multiple port rotary valve for flow switching comprises a rotor (2), a stator (7), a compressor supply (8) and a compressor return (6). Gas is supplied via the compressor supply throughout a switching cycle such that the rotor is lifted away from the stator (7). The valve further comprises a balance ram to counteract the effect of the differential pressure produced by the compressor supply, such that a gas seal is formed at the rotor/stator interface.
摘要翻译： 用于流量切换的多口旋转阀包括转子（2），定子（7），压缩机供应装置（8）和压缩机回流装置（6）。 在整个开关周期内通过压缩机供应气体，使得转子离开定子（7）。 该阀还包括平衡推杆，以抵消由压缩机供应产生的压差的影响，使得在转子/定子界面处形成气密封。
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公开(公告)号：EP0773450B1
公开(公告)日：2002-12-18
申请号：EP96116418.3
申请日：1996-10-14
IPC分类号： G01R33/3815 , H01F6/06
CPC分类号： G01R33/3815 , H01F6/065
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公开(公告)号：EP1128535A2
公开(公告)日：2001-08-29
申请号：EP01200455.2
申请日：2001-02-08
IPC分类号： H02M3/156
CPC分类号： H02M3/156
摘要： An apparatus for and method of control of a switch (102) in an electrical power converter (100) using pulse width modulation to regulate output voltage (112) and current. The method allows precise output voltage regulation to be achieved whilst accurately controlling the proportion of load-current supplied by multiple modules connected in parallel. A ramped waveform (408), consisting of a component representing the instantaneous current and a component representing the input voltage applied since the switch (102) switched on in the current PWM cycle, is compared with an error signal (406) to determine the width of each PWM pulse.
摘要翻译： 一种使用脉冲宽度调制来调节输出电压（112）和电流的电力转换器（100）中的开关（102）的控制装置和方法。 该方法允许精确的输出电压调节，同时精确控制由并联连接的多个模块提供的负载电流的比例。 将表示瞬时电流的分量和表示在当前PWM周期中接通的开关（102）所施加的输入电压的分量组成的斜坡波形（408）与误差信号（406）进行比较，以确定宽度 的每个PWM脉冲。
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公开(公告)号：EP1124317A2
公开(公告)日：2001-08-16
申请号：EP01200452.9
申请日：2001-02-08
发明人： Hickman, Kevin
IPC分类号： H02M3/337
CPC分类号： H02M7/5236 , H02M2007/4815 , Y02B70/1441
摘要： There is disclosed a parallel loaded series resonant converter 300 suitable for supplying DC to a three axis gradient amplifier in an MRI system. In conventional resonant circuits, output voltage is regulated by controlling the switching frequency of an H-bridge or half bridge switching arrangement and the resonant circuit (334, 335) is under more stress at no load than at full load. The voltage across the resonant capacitor (334) is a function of the switching frequency, the load and the voltage applied across the resonant circuit (V A -V B ). In the present invention, the peak current at no load is reduced to lower than the peak current at full load by controlling the voltage applied to the resonant circuit (V A -V B ) rather than controlling the switching frequency.
摘要翻译： 公开了一种适用于向MRI系统中的三轴梯度放大器提供DC的并联负载串联谐振变换器300。 在传统的谐振电路中，通过控制H桥或半桥开关装置的开关频率来调节输出电压，并且谐振电路（334,335）在空载时处于比在满载时更大的应力。 谐振电容器（334）两端的电压是开关频率，负载和施加在谐振电路（VA-VB）两端的电压的函数。 在本发明中，通过控制施加到谐振电路（VA-VB）的电压而不是控制开关频率，将空载峰值电流降低到满负载下的峰值电流。
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19.发明公开
公开(公告)号：EP1112507A1
公开(公告)日：2001-07-04
申请号：EP99941743.9
申请日：1999-08-23
IPC分类号： G01R33/383
CPC分类号： G01R33/383 , G01R33/3804 , G01R33/389
摘要： Apparatus is provided for generating an accurate magnetic field in a magnetic resonance imaging device. The device comprises a number of permanent magnet assemblies (1) each of which is in thermal contact with a plate (5) having good thermal conductivity, the plate (5) is positioned between said permanent magnetic assemblies (1) and gradient coils (3). The plate (5) has connected thereto one or more temperature sensors (7) which provide a signal to control circuit (8) which is arranged to control the operation to a plurality of thermoelectric heat pumping devices (9) which are connected to a plate (5) so that the overall heat generated by the heat pumping devices (9) and the gradient coils (3) is kept constant and is dissipated by a yoke (10) of the magnetic resonance imaging apparatus.
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公开(公告)号：EP0959365A2
公开(公告)日：1999-11-24
申请号：EP99108413.8
申请日：1999-04-29
IPC分类号： G01R33/3875 , G01R33/385
CPC分类号： G01R33/3875
摘要： A magnetic resonance imaging system comprises a magnet (30) for generating a main magnetic field, a gradient coil (34) to superimpose a linearly varying magnetic field over the main magnetic field, and an RF coil (34) forming part of a transmit/receive system for signals which are used to construct an image. A shimset (32) is positioned between the magnet (30) and the gradient coil (34) to provide magnetic field correction and is constructed so as not to have axial and azimuthal symmetry. This is achieved by providing cutout portions (38) in the shimset (32) which are diametrically opposite each other, similar cutouts (40) being provided in the gradient coil (34) which are aligned with the cutout portions (38). The cutout portions (38, 40) accommodate the shoulders of larger patients, therefore reducing the need to extend the bore size of the magnetic resonance imaging system.
摘要翻译： 磁共振成像系统包括用于产生主磁场的磁体（30），用于在主磁场上叠加线性变化的磁场的梯度线圈（34），以及形成发射/ 接收用于构建图像的信号的系统。 垫片（32）位于磁体（30）和梯度线圈（34）之间，以提供磁场校正，并被构造为不具有轴向和方位对称性。 这通过在彼此沿径向相对的间隙（32）中设置切口部（38）来实现，在与切口部（38）对准的梯度线圈（34）中设置有相似的切口（40）。 切口部分（38,40）容纳较大患者的肩部，因此减少了延长磁共振成像系统的孔尺寸的需要。
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