分子基磁体[NCBzPy][Ni(dmit)2]的合成、表征和磁学性质

合成了一种新的取代苄基吡啶盐[NcBzpy]cl(1),1和NiCl2,dmit^2-反应生成分子基磁体[NCBzPy][Ni(dmit)2](2),其结构用元素分析、IR和UV进行了表征。并测定了2在2K～300K的变温磁化率,结果显示。相邻Ni^3 之间存在铁磁偶合作用。     

永磁合金中钴铬锰测定方法的研究

研究了在含钻铬锰永磁合金中,在酸性环境及加热条件下,以过硫酸铵将锰氧化成MnO_2·xH_2O而沉淀分离。滤液经掩蔽其它元素后,加过量乙二胺四乙酸二钠盐标准溶液,以氯化锌标准溶液返滴定测定钴。铬及锰以氧化还原法连续测定。方法准确度高,精密度好,回收率大于99.6％,结果满意。     

应用于气炮上测量材料质点速度的恒磁质点速度计的研制

研制了一种应用于气炮上测量质点速度的恒磁质点速度计,此装置操作简单、稳定可靠。     

HT-7U托卡马克核聚变装置中纵场超导磁体系统的设计

HT-7U核聚变实验装置是"九五"国家重大科学工程项目,它是一个具有非圆截面的全超导托卡马克装置,是用于研究先进的托卡马克运行模式来获得准稳态的、极长的长脉冲等离子体,并可实现全电流下的双零高β和单零等离子体的运行实验。整个装置包括装置主机以及低温、真空、电源及控制、数据采集和处理、波加热、波驱动电流、诊断与公共基础设施等重要子系统,其中装置主机是由超导纵场磁体系统、超导极向场磁体系统、真空室及其内部部件、内外冷屏和外真空杜瓦5大部件组成。文章主要介绍了HT-7U纵场超导磁体系统结构与超导管状电缆CICC(Cable-in-ConduitConductor)的设计以及该磁体系统的各种力学分析等。     

车用永磁式缓速器电磁场数值模拟与试验

利用ANSYS软件对永磁式缓速器的电磁场进行计算.基于数值模拟计算结果,重点分析了材料区和气隙的磁感应强度的分布特性,并将实验结果与理论计算结果进行对比分析,表明数值计算结果误差在8%以内.通过对数值模拟结果进行细致分析,可深入了解其电磁场特性及工作机理,为解决永磁式缓速器的应用提供技术参考.     

Slow Magnetic Relaxation in {[CoCxAPy)] 2.15 H2O}n MOF Built from Ladder-Structured 2D Layers with Dimeric SMM Rungs

We present the magnetic properties of the metal-organic framework {[CoCxAPy]·2.15 H₂O}_n (Cx = bis(carboxypropyl)tetramethyldisiloxane; APy = 4,4′-azopyridine) (1) that builds up from the stacking of 2D coordination polymers. The 2D-coordination polymer in the bc plane is formed by the adjacent bonding of [CoCxAPy] 1D two-leg ladders with Co dimer rungs, running parallel to the c-axis. The crystal packing of 2D layers shows the presence of infinite channels running along the c crystallographic axis, which accommodate the disordered solvate molecules. The Co(II) is six-coordinated in a distorted octahedral geometry, where the equatorial plane is occupied by four carboxylate oxygen atoms. Two nitrogen atoms from APy ligands are coordinated in apical positions. The single-ion magnetic anisotropy has been determined by low temperature EPR and magnetization measurements on an isostructural compound {[Zn_0.8Co_0.2CxAPy]·1.5 CH₃OH}_n (2). The results show that the Co(II) ion has orthorhombic anisotropy with the hard-axis direction in the C_2V main axis, lying the easy axis in the distorted octahedron equatorial plane, as predicted by the ab initio calculations of the g-tensor. Magnetic and heat capacity properties at very low temperatures are rationalized within a S* = 1/2 magnetic dimer model with anisotropic antiferromagnetic interaction. The magnetic dimer exhibits slow relaxation of the magnetization (SMM) below 6 K in applied field, with a τ_lf ≈ 2 s direct process at low frequencies, and an Orbach process at higher frequencies with U/k_B = 6.7 ± 0.5 K. This compound represents a singular SMM MOF built-up of Co-dimers with an anisotropic exchange interaction.     

基于变结构MRAS观测器的PMSM无速度传感器矢量控制

为改善传统模型参考自适应系统(Model Reference Adaptive System, MRAS)速度观测器对电机参数和负载变化敏感的缺点,针对永磁同步电机,基于变结构技术,提出一种变结构MRAS速度观测器。该方法利用滑模变结构代替MRAS中的自适应律,利用连续的双曲正切函数Sigmoid代替符号切换函数,可以降低滑模模态的抖动。理论分析和仿真结果表明,基于变结构MRAS观测器的PMSM无速度传感器矢量控制系统具有较好的动静态性能,且具有较强的鲁棒性。     

基于SVM的永磁同步电机直接转矩控制

参考电压矢量的计算是基于空间矢量调制(space vector modulation, SVM)的永磁同步电机直接转矩控制的核心研究之一. 从电压矢量对电磁转矩的控制作用入手, 分析指出有限的电压矢量是直接转矩控制中转矩和磁链脉动大的根本原因. 设计一种改进的基于空间矢量调制的直接转矩控制系统, 仅仅利用定子磁链角度、转矩偏差和定子磁链偏差计算得到参考电压矢量幅值和角度. 该方案计算简单, 对电机参数不敏感. 仿真和实验结果表明, 该方法结构简单、鲁棒性强, 能够明显改善直接转矩控制性能.     

Design and development of the 6–18 MeV electron beam system for medical and other applications

A system for the electron and photon therapy has been designed and developed at SAMEER, IITB, Mumbai. All the components of the system such as the 270° beam bending electromagnet, trim coils, magnet chamber, electron scattering foil, slits, applicators, etc., were designed and fabricated indigenously. The electrons of 6, 8, 9, 12, 15 and 18?MeV energies were provided by a linear accelerator, indigenously designed and made at SAMEER, IITB campus, Mumbai. The electron beam from the LINAC enters the magnet chamber horizontally, and after deflection and focusing in the 270° bending magnet, comes out of the exit port, and travels a straight path vertically down. After passing through the beryllium and tantalum scattering foils, the electron beam gets scattered and turns into a solid cone shape such that the diameter increases with the travel distance. The simulation results indicate that at the exit port of the 270° beam bending magnet, the electron beam has a divergence angle of ≤ 3?mrad and diameter ～2–3?mm, and remains constant over 6–18?MeV. Normally, 6–18?MeV electrons are used for the electron therapy of skin and malignant cancer near the skin surface. On a plane at a distance of 100?cm from the scattering foils, the size of the electron beam could be varied from 10?cm?×?10?cm to 25?cm?×?25?cm using suitable applicators and slits. Different types of applicators were therefore designed and fabricated to provide required beam profile and dose of electrons to a patient. The 6?MeV cyclic electron accelerator called Race-Track Microtron of S. P. Pune University, Pune, was extensively used for studying the performances of the scattering foils, electron beam uniformity and radiation dose measurement. Different types of thermoluminescent dosimetry dosimeters were developed to measure dose in the range of 1–10kGy.     

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为了解不同氦气状态对超导托卡马克室温绝缘子电性能的影响,建造了室温绝缘子氦气状态下电性能测试平台.利用该平台,在静态氦气和氦气流速为0.65g·s?1状态下进行了室温绝缘子高电压-漏电流实验.实验结果表明,两种氦气状态下室温绝缘子均满足使用要求.