To solve three-dimensional structures of biological macromolecules in situ, large numbers of particles often need to be picked from cryo-electron tomograms. However, adoption of automated particle-picking methods remains limited because of their technical limitations. To overcome the limitations, we develop DeepETPicker, a deep learning model for fast and accurate picking of particles from cryo-electron tomograms. Training of DeepETPicker requires only weak supervision with low numbers of simplified labels, reducing the burden of manual annotation. The simplified labels combined with the customized and lightweight model architecture of DeepETPicker and accelerated pooling enable substantial performance improvement. When tested on simulated and real tomograms, DeepETPicker outperforms the competing state-of-the-art methods by achieving the highest overall accuracy and speed, which translate into higher authenticity and coordinates accuracy of picked particles and higher resolutions of final reconstruction maps. DeepETPicker is provided in open source with a user-friendly interface to support cryo-electron tomography in situ.

High temperature superconducting (HTS) coils are key parts of many AC applications, such as generators, superconducting magnetic energy storage and transformers. AC loss reduction in HTS coils is essential for the commercialization of these HTS devices. Magnetic material is generally used as the flux diverter in an effort to reduce the AC loss in HTS coils. To achieve the greatest reduction in the AC loss of the coils, the flux diverter should be made of a material with low loss and high saturated magnetic density, and the optimization of the geometric size and location of the flux diverter is required. In this paper, we chose Ni-alloy as the flux diverter, which can be processed into a specific shape and size. The influence of the shape and location of the flux diverter on the AC loss characteristics of stacked (RE)BCO tapes is investigated by use of a finite element method. Taking both the AC loss of the (RE)BCO coils and the ferromagnetic loss of the flux diverter into account, the optimal geometry of the flux diverter is obtained. It is found that when the applied current is at half the value of the critical current, the total loss of the HTS stack with the optimal flux diverter is only 18% of the original loss of the HTS stack without the flux diverter. Besides, the effect of the flux diverter on the critical current of the (RE)BCO stack is investigated.

Although AC transport losses of YBa₂Cu₃O_7−δ (YBCO) coated conductors (CCs) have been studied extensively, the frequency dependence of transport losses still needs more investigations. This paper presents a study on the frequency dependence (in the range of 50–1000 Hz) of the transport losses in YBCO CCs with ferromagnetic substrate and copper stabilizer by the use of both experimental and finite element methods (FEMs). The finite element model (FEM) is based on H‐formulation and E-J power law, and calculated AC transport losses accord with the experimental ones. The contributions of ferromagnetic (Ni-5at.%W substrate), eddy current (conventional metal), and hysteresis (superconducting YBCO) losses are extracted. It is shown that the AC transport loss per cycle increases with the frequency due to the growing contribution of eddy current loss. More than 80% of eddy current loss comes from the copper stabilizer adjacent to the ferromagnetic substrate. The influence of magnetic substrate on AC loss is also studied, and it is found that YBCO CCs with non-magnetic substrates are more suitable for high-frequency applications.

This paper focuses on the study of the frequency-dependent transport ac loss of YBa ₂ Cu ₃ O _{7− δ} (YBCO) coils and how it is influenced by flux diverters. A single pancake coil is wound by AMSC 8501 tape and its transport ac losses (in the frequency range of 50–1000 Hz) are investigated through the use of both experimental and finite element methods. The finite element model is based on the H-formulation and E-J power law, and it takes both the magnetic field dependences of critical current density and degradation of critical current density close to the edges into account. Different loss components (namely hysteresis losses in HTS layers, ferromagnetic losses in weakly magnetic substrates, eddy current losses in conventional metal and ferromagnetic losses in flux diverters) of YBCO-NiW coils at different frequencies are calculated by using the numerical model. The calculated ac losses accord well with the measured ones, which validates the numerical model. The influence of the flux diverter on different loss components at low/high frequencies is analyzed numerically. It is found that the flux diverter greatly decreases the hysteresis loss per cycle, but causes an enhancement of both eddy current and ferromagnetic losses per cycle. We propose a new parameter f c to clarify the region where flux diverters can effectively decrease the transport ac loss per cycle of the YBCO-NiW coil.

There are some disadvantages in conventional cryogenic liquid pumps (CLPs) with mechanical bearings, such as difficult lubrication and short working life. In this paper, we propose a new structure of CLP-submerged cryogenic disk motor-pump with superconducting magnetic bearing (SMB). The impeller and the rotor of the disk motor are combined as the suspension rotor of the disk motor-pump. The suspension rotor which is supported by SMB system, rotates frictionlessly with self-stabilized. The SMB system includes a radial-type SMB, an axial-type permanent magnet bearing, and an axial flux disk motor. Theoretical calculations and experimental measurements of levitation forces in the SMB system are carried out. The levitation force of radial-type SMB is calculated by using H -formulation finite-element model in COMSOL. The kinetic model of the suspension rotor is established to ensure the force balance and torque balance. The results demonstrate the feasibility of the proposed submerged cryogenic disk motor-pump with SMB.

Wireless power transfer (WPT) is of increasing interests today. High temperature superconducting (HTS) WPT has been demonstrated to be more efficient than copper WPT. In our previous work, we found that the efficiency of WPT from a copper coil to a HTS coil is lower than the efficiency of WPT from the same HTS coil to the same copper coil. Thus, the transmitter and the receiver are asymmetric and this asymmetry degrades WPT performance. In this paper, it is demonstrated theoretically and experimentally that for WPT between a HTS coil and a copper coil: asymmetry does exist and influences properties; the root of the asymmetry is the different resistances between the HTS coil and the copper coil; the effects of the asymmetry can be eliminated by optimizing the load; the proposed theoretical calculation fits the experimental results well.