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A hybrid double stator bearingless switched reluctance motor with advantages of high suspension output, small loss and weak coupling is presented. This motor can realise electric/power generation and radial two-degree-of-freedom suspension. The biased magnetic field for producing radial force is provided by a permanent magnet, which reduces system power consumption. Self-decoupling is realised between a torque system and suspension system according to the mechanical structure design. Furthermore, the radial force is approximately constant when the suspension current is constant, thereby improving the controllability of the system. The operation principle is introduced and the electromagnetic characteristics are analysed through the timestepping finite element method. This analysis verifies the effectiveness of the theoretical analysis. Introduction: The structure of magnetic bearings (MBs) is similar to that of the switched reluctance motor (SRM) stator; thus, the bearingless technology is applied to SRM to maximise its high-speed performance [1]. The bearingless SRM (BSRM) which combines the merits of SRM and MB can rotate and levitate simultaneously by integrating the magnetic levitation winding into the stator of motor. Several types of BSRMs have been proposed. On the design front, 12/8 BSRM was proposed by Takemoto et al. [1], 8/6 single winding BSRM was proposed by Chen and Hofmann [2], 12/8 single winding BSRM was proposed by Liu and Yang in [3]. Moreover, BSRM with special structures [4, 5] (double-stator, hybrid-stator and hybrid-rotor) was proposed. In this Letter, the idea of 'hybrid excitation' is introduced into double stator BSRM (DSBSRM), and a new hybrid DSBSRM (HDSBSRM) is presented. The structure, operation principle and main electromagnetic characteristics of the HDSBSRM are analysed.

A novel bearingless segmented switched reluctance motor (BSSRM) is proposed in this paper to solve the coupling problem of the traditional bearingless switched reluctance motor (BSRM). Different from traditional BSRMs, the proposed BSSRM adopts the double stator and segmented rotor structure, thereby making the motor operate in short flux paths and the magnetic flux path isolated between torque and suspension system. On the basis of introducing the structure and working principle of the BSSRM, the mathematical model of torque and suspension force is deduced. The 2D finite element simulation model is established by the Ansoft software. The influence of structural parameters on torque and suspension system is analyzed, and its electromagnetic characteristic and decoupling characteristic are analyzed. Compared with the double stator bearingless switched reluctance motor (DSBSRM), the BSSRM not only improves the torque and suspension output but also weakens the coupling between torque and suspension system. Finally, the simulation results verify the effectiveness of the BSSRM. INDEX TERMSBearingless switched reluctance motor, segmented rotor, decoupling characteristic, electromagnetic characteristic.

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Human sperm DNA is an important genetic and epigenetic material, whose chromatin structure differs from that of somatic cells. As such, conventional methods for DNA extraction of somatic cells may not be suitable for obtaining sperm DNA. In this study, we evaluated and compared three sperm DNA extraction techniques, namely, modified guanidinium thiocyanate method (method A), traditional phenol-chloroform method (method B), and TianGen kit method (method C). Spectrophotometry and agarose gel electrophoresis analyses showed that method A produced DNA with higher quantity and purity than those of methods B and C (P<0.01). PCR results revealed that method A was more reliable in amplifying DEAD-box polypeptide 4 (DDX4) and copy number variations (CNVs) than methods B and C, which generated false-positive errors. The results of sperm DNA methylation assay further indicated that methods A and B were effective, and the former yielded higher quantitative accuracy. In conclusion, the modified guanidinium thiocyanate method provided high quality and reliable results and could be an optimal technique for extracting sperm DNA for methylation assay.

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