基于0—1整数线性规划的自屏蔽磁共振成像超导磁体设计

0—1 integer linear programming for actively shielded magnetic resonance image (MRI) superconducting magnet design

本文提出一种基于0—1整数线性规划的自屏蔽磁共振成像(MRI)超导磁体设计方法.在磁体线圈可行载流区内按照所用线材尺寸划分网格,同时综合考虑线材内最大磁感应强度、成像区磁场均匀度、漏场范围等设计要求,以超导线材使用量最小为目标函数,采用0—1整数线性规划算法得到磁体线圈的初始导线集中区块分布;然后通过合理的调整限制各分离导线区块截面尺寸及其中心位置,得到最终易于实际加工和绕制的矩形磁体线圈结构.并根据不同的约束要求,该方法也适用于其他结构超导磁体的优化设计.文中最后给出一个设计实例.

Here introduced is an optimization design method for actively shielded magnetic resonance image （MRI） superconducting magnet based on the integer linear programming. The feasible coil space is densely divided by an array of candidate squares and, its size is determined by the size of actual superconducting wire. The 0--1 integer linear programming method is adopted to obtain the initial wire concentrated region of coils by comprehensivly considering superconductivity wire consumption, magnetic field intensity inside the superconductors, homogeneity in imaging region and the range of leak fields. Then by reasonably adjusting the position and section size of the wire concentrated region for the next calculation, the final MRI superconducting magnet structure with rectangular section coils is obtained. The method is based on the full size of the superconducting wire, which makes the MRI superconducting magnet design more feasible and has greater advantage for the actual fabriction. With different constraints, the method can also be used for other superconducting magnet design. Finally an example of the MRI magnet optimal design is presented.