Biblio
This paper presents an analytical method for predicting the electromagnetic performance in permanent magnet (PM) machine with the spoke-type rotor (STR) and a proposed hybrid rotor structure (HRS), respectively. The key of this method is to combine magnetic field analysis model (MFAM) with the magnetic equivalent circuit model. The influence of the irregular PM shape is considered by the segmentation calculation. To obtain the boundary condition in the MFAM, respectively, two equivalent methods on the rotor side are proposed. In the STR, the average flux density of the rotor core outer-surface is calculated to solve the Laplace's equation with considering for the rotor core outer-surface eccentric. In the HRS, based on the Thevenin's theorem, the equivalent parameters of PM remanence BreB and thickness hpme are obtained as a given condition, which can be utilized to compute the air-gap flux density by conventional classic magnetic field analysis model of surface-mounted PMs with air-gap region. Finally, the proposed analytical models are verified by the finite element analysis (FEA) with comparisons of the air-gap flux density, flux linkage, back-EMF and electromagnetic torque, respectively. Furthermore, the performance that the machine with the proposed hybrid structure rotor can improve the torque density as explained.
Public key infrastructure (PKI) is the foundation and core of network security construction. Blockchain (BC) has many technical characteristics, such as decentralization, impossibility of being tampered with and forged, which makes it have incomparable advantages in ensuring information credibility, security, traceability and other aspects of traditional technology. In this paper, a method of constructing PKI certificate system based on permissioned BC is proposed. The problems of multi-CA mutual trust, poor certificate configuration efficiency and single point failure in digital certificate system are solved by using the characteristics of BC distribution and non-tampering. At the same time, in order to solve the problem of identity privacy on BC, this paper proposes a privacy-aware PKI system based on permissioned BCs. This system is an anonymous digital certificate publishing scheme., which achieves the separation of user registration and authorization, and has the characteristics of anonymity and conditional traceability, so as to realize to protect user's identity privacy. The system meets the requirements of certificate security and anonymity, reduces the cost of CA construction, operation and maintenance in traditional PKI technology, and improves the efficiency of certificate application and configuration.
A THz image edge detection approach based on wavelet and neural network is proposed in this paper. First, the source image is decomposed by wavelet, the edges in the low-frequency sub-image are detected using neural network method and the edges in the high-frequency sub-images are detected using wavelet transform method on the coarsest level of the wavelet decomposition, the two edge images are fused according to some fusion rules to obtain the edge image of this level, it then is projected to the next level. Afterwards the final edge image of L-1 level is got according to some fusion rule. This process is repeated until reaching the 0 level thus to get the final integrated and clear edge image. The experimental results show that our approach based on fusion technique is superior to Canny operator method and wavelet transform method alone.