Lei Wang

Institute of Electrical Engineering

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Qiuliang Wang

Institute of Electrical Engineering

Jianhua Liu

Institute of Electrical Engineering

Zili Zhang

China University of Geosciences (Beijing)

Yanwei Ma

Institute of Electrical Engineering

Dongliang Wang

China Meteorological Administration

Xianping Zhang

Chinese Academy of Sciences

Yanpeng Qi

ShanghaiTech University

Xinning Hu

Fujian Medical University

Benzhe Zhou

University of Chinese Academy of Sciences

Zhaoshun Gao

Institute of Electrical Engineering

Cooperative Institutions

Chinese Academy of Sciences

234

University of Chinese Academy of Sciences

120

Institute of Electrical Engineering

Shanghai Jiao Tong University

University of Science and Technology of China

Campbell Collaboration

Peking University

Tsinghua University

Sun Yat-sen University

Central South University

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Energy Harvesting and Thermal Management System in Aerospace

Frontiers in Materials (2022)

Fan Jiang Shiyu Zhao Lei Wang YU Shan-meng Hongyu Guan

Energy harvesting and thermal management in spacecraft refer to the adjustment, distribution, and comprehensive use of uniform adjustment, allocation, and integrated use of the spacecraft and subsystems, which have the advantages of reducing energy consumption and improving the overall performance of the spacecraft. The study is first briefly elaborated on the research progress of energy harvesting and thermal management, and then introduces the key thermal control technology of thermal management, mainly thermal bus systems, heat pump technology, and passive thermal control technology. Finally, the future development direction and research focus of thermal management are proposed, which lays a foundation for the future development of energy harvesting and thermal management technology.

Thermal energy

10.3389/fmats.2022.907858

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Citations (4)

The Effect of Winding Conditions on the Stress Distribution in a 10.7 T REBCO Insert for the 25.7 T Superconducting Magnet

IEEE Transactions on Applied Superconductivity (2017)

Lei Wang Qiuliang Wang Lankai Li Lang Qin Jianhua Liu

A 25.7 T/32 mm all-superconducting nuclear magnetic resonance magnet, consisting of a 10.7 T/32 mm rare earth-barium-copper-oxide (REBCO) high temperature superconducting (HTS) insert and a 15 T/160 mm low temperature superconducting magnet, has been manufactured at the Institute of Electrical Engineering, Chinese Academy of Sciences. There is a large electromagnetic force induced in the HTS insert after the superconducting magnet is energized, which may cause the mechanical failure of the REBCO tape. To protect the HTS insert during its energization, it is necessary to apply suitable winding tension on the REBCO tape and overband. In this paper, the effect of winding conditions on the stress distribution in the HTS coil was investigated, in which the winding tension applied on the REBCO tape and overband on the HTS insert were included. A checking test was conducted after the superconducting magnet quenched at 25.7 T, which shows that the HTS coil did not burn out and suffer catastrophic damage. The optimized pretension load and overband conditions utilized to wind the HTS coil could protect it from the excessive electromagnetic force when the central field exceeded 25 T.

Insert (composites)

10.1109/tasc.2017.2778739

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Citations (14)

Systematic investigation of a NbTi-Bi2223 hybrid low-resistive joint

Superconductor Science and Technology (2023)

Wanshuo Sun Yaohui Wang Zili Zhang Xiaolong Zhang Lei Wang

Abstract In this study, a NbTi-Bi2223 hybrid low-resistive joint fabricated by the superconducting solder method was systematically investigated. The joint is a necessary component of gigahertz nuclear magnetic resonance (NMR) with Bi2223 as the insert coil. The joint resistance and current capability under different applied magnetic fields were measured, and the resistance exhibited a near-linear relationship with the applied field. Beyond the superconducting properties, the allowed mechanical criteria for the Bi2223 tape in the joint were also briefly studied. Based on the above two properties, a 1.3 GHz NMR design with a NbTi-Bi2223 hybrid low-resistive joint was shown as an application demonstration. Although the current resistance can fit the magnetic-field decay criteria, obtaining a lower resistance value was attempted by extending the joint length but failed. The main source of the resistance in NbTi-Bi2223 was studied. We attempt to show an engineering-feasible NbTi-Bi2223 hybrid low-resistive joint to help improve the development of gigahertz NMR.

Resistive touchscreen

10.1088/1361-6668/acd881

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Determination of electron mobility in a blue-emitting alternating block copolymer by space-charge-limited current measurements

Solid State Communications (1999)

Dongge Ma Ivo A. Hümmelgen B. Hu Frank E. Karasz Xiping Jing

Electron Mobility

Charge carrier

10.1016/s0038-1098(99)00351-8

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Citations (23)

Numerical Analysis of Mechanical Behavior for a 9.4-T Whole-Body MRI Magnet

IEEE Transactions on Applied Superconductivity (2016)

Lankai Li Junsheng Cheng Chunyan Cui Yi Li Yinming Dai

A whole-body high-field MRI magnet is being constructed. A compensation solenoid method was employed to design the coil configuration for the magnet. In order to manage the mechanical stress, we sectioned the long solenoid into six windings, and they were wound on five aluminum alloy mandrels. Four compensation coils were wound outside of the long solenoid windings to compensate the field inhomogeneity of imaging region. Preliminary analysis used by a simplified method has been conducted to estimate the stress levels and coil deformations. Furthermore, a finite-element method (FEM) was used to obtain the stress distribution of the magnet structure fully. The electromagnetic stresses, the sliding behavior, and the quench dynamic stresses were simulated by these FEM models. The cumulative stresses caused by winding pretension and thermal contractions were used as initial stresses to calculate the frictional stresses for the interface contact analysis. The quench-induced stresses and deformations of thermal shields are also discussed. The results are exploited to conduct mechanical design and construction of the magnet.

Solenoid

10.1109/tasc.2016.2632899

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Citations (13)

Numerical simulation based radial laser cladding process optimisation for annular thin-walled parts

International Journal of Engineering Systems Modelling and Simulation (2022)

Baotong Chen Tong Wang Ping Yi Xuhui Xia Zelin Zhang

Cladding (metalworking)

10.1504/ijesms.2022.10048707

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Citations (0)

Finite-size and interaction effects on topological phase transitions via numerically exact quantum Monte Carlo calculations

arXiv (Cornell University) (2013)

Hsiang-Hsuan Hung Victor Chua Lei Wang Gregory A. Fiete

We theoretically study topological phase transitions in two generalized versions of the Kane-Mele-Hubbard model on a finite portion of the honeycomb lattice with up to $2\times 18^2$ sites. Both models are free of the fermion-sign problem allowing numerically exact quantum Monte Carlo calculations to be performed in the low-temperature regime. We numerically compute the $Z_2$ invariant and the spin-Chern number directly from the zero-frequency single-particle Greens function for different values of on-site interaction and tune tight-binding parameters to drive topological phase transitions. While phase boundaries are nearly identical for different system sizes, we find a rather strong system-size dependence of the spin Chern number, with the expected quantized value only slowly approached for the largest system sizes. Moreover, we find that quantum fluctuation effects from interactions can act both to stabilize and destabilize topological phases, depending on the details of the model.

Lattice (music)

Source

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Citations (1)

The force model of wireless active actuation for capsule endoscope in the GI tract

2021 IEEE International Conference on Robotics and Biomimetics (ROBIO) (2007)

Dongmei Chen Chao Hu Lei Wang Max Q.‐H. Meng

We presents a new closed loop approach for the active actuation of wireless capsule endoscope inside the human GI tract. A magnet is enclosed in the capsule, and its position, orientation, and movement are detected by a magnetic localization system. To actuate the capsule, an external rotative magnetic field is applied around human body such that a driving force is created in the capsule by the magnet. Through the spiral structure on the capsule surface, the capsule is rotated to move forward or backward with the aid of mucus of the GI tract. According to the hydromechanical lubrication theory and Newton viscous law, we build the traction force model, the friction force model and the locomotion speed model. In this paper, the simulation results of all these three mathematical models are given, which will provide theoretical guide to design the spiral impeller structure of the capsule and estimate the motion force induced by external magnetic field.

Capsule

10.1109/robio.2007.4522141

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Citations (8)

Development of YBCO insert for a 25 T all superconducting magnet

Jian Hua Liu Shou Seng Song Chen Gou Jian Zhou Lei Wang

Recently, a superconducting magnet with the center field of 25 T at 4.2 K and a warm bore-size of 32 mm in diameter has been designed and fabricated in Institute of Electrical Engineering (IEE). The 25 T superconducting magnet consists of NbTi, Nb3Sn and YBCO inserts. YBCO insert has been designed, fabricated and tested in the liquid helium at IEE so as to prove the technical feasibility to achieve the target of 25 T. The critical current distribution, hoop stress, radial stress and fabrication techniques are addressed. The YBCO insert has the inner diameter, outer diameter, and height of 24 mm, 65 mm, and 204 mm, respectively. The YBCO insert was assembled with a Bi2223 magnet which provide a background magnetic field of 5.8 T with a design operating current of 150 A. As for the YBCO insert, a 5.3 T central magnetic field can be obtained at the design operating current of 150 A. Test results show that a 5.5 T central magnetic field can be obtained in the central bore of YBCO insert at the operating current of 150 A, self-field; and the combination of these two insert coils can generate a center magnetic field of 11 T at 4.2 K. In this paper, the design, fabrication and preliminary experiment are reported.

Insert (composites)

10.1109/asemd.2015.7453647

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Citations (6)

Numerical Analysis of Eddy Current Induced by z-Gradient Coil in a Superconducting MRI Magnet

IEEE Transactions on Applied Superconductivity (2020)

Chaoqun Niu Lei Wang Yaohui Wang Yujia Zhai Hongyi Qu

In magnetic resonance imaging (MRI), pulsed magnetic gradient fields induce eddy currents in surrounding conducting components of the MRI scanner. These eddy currents distort MRI image and introduce thermal load in cryostat. Ohmic heating of superconducting magnet due to eddy currents changes the operating temperature of magnet, which can lead to system quench. Numerical simulation of these eddy current is important to compensate/control their adverse effects. In this paper, a coupled circuit network method is outlined to model eddy currents in a superconducting magnet that induced by z-gradient coil. According to the axial symmetry, the cylindrical cryostat vessels are divided into several concentric slices with a finite thickness. Each slice is modeled as a series circuit composed of a resistor and an inductor, and inductively coupled with other slices and gradient coil. To improve the calculation efficiency, the Eigen matrix technique is used to simplify the coupled differential matrix equation. The undesired eddy current effects including time-varying secondary magnetic field and power losses are analyzed. In addition, the eddy current behavior due to mechanical errors of gradient coil is discussed. Compared with the simulation results of ideal gradient coil design, the misalignment between primary and secondary layer of z-gradient coil can cause asymmetric secondary magnetic field along z-axis and further introduce B ₀ -shift in imaging area.

Cryostat

10.1109/tasc.2020.2969398

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Citations (5)