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Privacy protection in data publishing is an extremely important issue that has been the focus of extensive research in recent years. However, the existing methods have a host of limitations, especially for high-dimensional data publishing. Aiming at the problem of poor availability of publishing results caused by “the curse of dimensionality” in high-dimensional data publishing, we present PPDP-PCAO (Privacy Preserving Data Publishing with Principal Component Analysis Optimization) method, which can better address the problem of the lower utility of release results because of the high noise introduced by the curse of dimensionality. PPDP-PCAO improves the Principal Component Analysis (PCA) algorithm by employing the attribute importance, and reduces the dimension of the data with the improved PCA, which reduces the time and space cost. PPDP-PCAO introduces the evaluation mechanism based on mutual-information into data release, which evaluates the data generated by setting the different quantities of principal components to determine the optimal quantities. PPDP-PCAO considers the existence of multi-sensitive attributes in high-dimensional data, while the traditional methods of allocating privacy budgets cannot satisfy the personalized privacy protection. PPDP-PCAO introduces the sensitivity preference, combines the optimal matching theory, and designs the sensitive attribute hierarchical protection strategy. Extensive experimental results on different real datasets demonstrate that PPDP-PCAO not only guarantees the privacy of published dataset, but also significantly improves the accuracy and data utility than other high-dimensional data publishing methods.

For stable and safe operation of high-temperature superconducting flywheel energy storage system, adequate levitation force and stiffness of the high-temperature superconducting magnetic bearing (SMB) are necessary. In order to validate the design and research the levitation characteristics further, a threedimensional measurement system for high-temperature SMB is developed in our laboratory. The measurement system consists of experiment system, motor drivers, data acquisition and processing, automatic control, and auxiliary devices. The measurement system has the following characteristics: high measurement precision and sensitivity, measurement suitable for both axial-type and radial-type SMB with different diameter and height, measurement of the axial and radial levitation forces, stiffness, and time relaxation, and measurement of force with precise displacement in three-dimensional space. The maximal axial and radial levitation forces that the measurement system can measure are 3000 and 2000 N with the precision of 1.5‰. The measurement precision is calibrated and the test results for high-temperature SMB are presented. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The magnetism of substrate has significant influence on the transport loss in high temperature superconducting (HTS) coated conductors (CCs). Taking three types of substrates (i.e., nonmagnetic, weakly magnetic, and strongly magnetic) into account, a study on the frequency dependence (in the range of 10-1000 Hz) of transport loss in HTS CCs with these substrates is performed numerically and experimentally. Different loss components and magnetic field profile are calculated individually to clarify the effect of substrate magnetism. Results show that HTS CCs with magnetic substrate exhibit higher transport loss than CCs with nonmagnetic substrate. Both hysteresis loss in HTS layer and eddy current loss in conventional metal increase with the enhancement of substrate magnetism. [ABSTRACT FROM AUTHOR]