Investigation of novel multi-layer spoke-type ferrite interior permanent magnet machines

The permanent magnet synchronous machines have been attracting more and more attention due to the advantages of high torque density, outstanding efficiency and maturing technologies. Under the urges of mandatory energy efficiency requirements, they are considered as the most potential candidates to replace the comparatively low-efficient induction machines which dominate the industrial market. However, most of the high performance permanent magnet machines are based on high cost rare-earth materials. Thus, there will be huge demands for low-cost high-performance permanent magnet machines. Ferrite magnet is inexpensive and abundant in supply, and is considered as the most promising alternative to achieve the goal of low cost and high performance. In consideration of the low magnetic energy, this thesis explored the recent developments and possible ideas of ferrite machines, and proposed a novel multi-layer spoke-type interior permanent magnet configuration combining the advantages of flux focusing technique and multi-layer structure. With comparable material cost to induction machines, the proposed ferrite magnet design could deliver 27% higher power with 2-4% higher efficiency with exactly the same frame size. Based on the data base of International Energy Agency (IEA), electricity consumed by electric machines reached 7.1PWh in 2006 [1]. Considering that induction machines take up 90% of the overall industrial installation, the potential energy savings is enormous. This thesis contributes in five key aspects towards the investigation and design of low-cost high-performance ferrite permanent magnet machines. Firstly, accurate analytical models for the multi-layer configurations were developed with the consideration of spatial harmonics, and provided effective yet simple way for preliminary design. Secondly, the influence of key design parameters on performance of the multi-layer ferrite machines were comprehensively investigated, and optimal design could be carried out based on the insightful knowledge revealed. Thirdly, systematic investigation of the demagnetization mechanism was carried out, focusing on the three key factors: armature MMF, intrinsic coercivity and working temperature. Anti-demagnetization designs were presented accordingly to reduce the risk of performance degradation and guarantee the safe operation under various loading conditions. Then, comparative study was carried out with a commercial induction machine for verification of the superior performance of the proposed ferrite machine. Without loss of generality, the two machines had identical stator cores, same rotor diameter and stacking length. Under the operating condition of same stator copper loss, the results confirmed the superior performance of the ferrite machine in terms of torque density, power factor and efficiency. Lastly, mechanical design was discussed to reduce the cost of mass production, and the experimental effort on the prototype machine validates the advantageous performance as well as the analytical and FEA predictions

Improving the accuracy and efficiency of docking methods

Computational methods for predicting macromolecular complexes are useful tools for studying biological systems. They are used in areas such as drug design and for studying protein-protein interactions. While considerable progress has been made in this field over the decades, enhancing the speed and accuracy of these computational methods remains an important challenge. This work describes two different enhancements to the accuracy of ClusPro, a method for performing protein-protein docking, as well as an enhancement to the efficiency of global rigid body docking. SAXS is a high throughput technique collected for molecules in solution, and the data provides information about the shape and size of molecules. ClusPro was enhanced with the ability to SAXS data collected for protein complexes to guide docking by selecting conformations by how well they match the experimental data, which improved docking accuracy when such data is available. Various other experimental techniques, such as NMR, FRET, or chemical cross linking can provide information about protein-protein interfaces, and such information can be used to generate distance-based restraints between pairs of residues across the interface. A second enhancement to ClusPro enables the use of such distance restraints to improve docking accuracy. Finally, an enhancement to the efficiency of FFT based global docking programs was developed. This enhancement allows for the efficient search of multiple sidechain conformations, and this improved program was applied to the flexible computational solvent mapping program FTFlex.2018-07-09T00:00:00

Minkowski Brane in Asymptotic dS5_5 Spacetime without Fine-tuning

We discuss properties of a 3-brane in an asymptotic 5-dimensional de-Sitter spacetime. It is found that a Minkowski solution can be obtained without fine-tuning. In the model, the tiny observed positive cosmological constant is interpreted as a curvature of 5-dimensional manifold, but the Minkowski spacetime, where we live, is a natural 3-brane perpendicular to the fifth coordinate axis.Comment: 6 pages, Latex fil