Cogging torque reduction of Bldc motor using level set based topology optimization incorporating with triangular finite element

Cogging torque in permanent-magnet brushless DC (BLDC) motor causes torque and speed ripples, as well as acoustic noise and vibration, especially in low speed and direct drive applications. In this paper, the stator core shape is optimized by using a level set based topology optimization to reduce cogging torque. The level set method can represent the precise boundary shape of structure and also deal with complex topology changes during the optimization process. Different from the conventional rectangular meshes, the level set technique based triangular finite element meshes are presented in this paper to deal with irregular domains. The comparison of cogging torque calculated before and after topology optimization verifies the advantages of the level set topology optimization based on triangular meshes. © 2010 - IOS Press and the authors. All rights reserved

Identification and expression analysis of vitellogenin from silk-producing insect, Actias selene Hubner

This study mainly shows the DNA sequence and expression analysis of vitellogenin in Actias selene (Ash-Vg). Specific primers were designed to amplify Ash-Vg gene by polymerase chain reaction (PCR) and the obtained DNA sequence was 7329 bp long, including 6 exons and 5 introns with an open reading frame encoding a 1774 amino acids peptide. A Bm DSX binding site and some conserved signatures such as CdxA and GATA-X were found in the 5Œ-flanking region of Ash-Vg gene. Meanwhile, the cDNAencoding the small subunit of Ash-Vg protein was obtained by PCR and ligated to pET-28a vector for protein expression. A 45 KD recombinant protein was successfully expressed in Escherichia coli cells which were confirmed by sodium dodesyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) and western blot analysis. The semi-quantitative PCR was also carried out to explore the specific expression of Ash-Vg and the results showed that the Ash-Vg gene expressed differently in various  developmental stages and tissues.Key words: Actias selene Hubner, vitellogenin, DNA sequence, expression

Vacancy-tuned paramagnetic/ferromagnetic martensitic transformation in Mn-poor Mn_{1-x}CoGe alloys

It is shown that a temperature window between the Curie temperatures of martensite and austenite phases around the room temperature can be obtained by a vacancy-tuning strategy in Mn-poor Mn1-xCoGe alloys (0 <= x <= 0.050). Based on this, a martensitic transformation from paramagnetic austenite to ferromagnetic martensite with a large magnetization difference can be realized in this window. This gives rise to a magnetic-field-induced martensitic transformation and a large magnetocaloric effect in the Mn1-xCoGe system. The decrease of the transformation temperature and of the thermal hysteresis of the transformation, as well as the stable Curie temperatures of martensite and austenite, are discussed on the basis of the Mn-poor Co-vacancy structure and the corresponding valence-electron concentration.Comment: Manuscript revised. 18 pages, 6 figures and 1 table. Submitted for publication

Reserpine-Induced Reduction in Norepinephrine Transporter Function Requires Catecholamine Storage Vesicles

Treatment of rats with reserpine, an inhibitor of the vesicular monoamine transporter (VMAT), depletes norepinephrine (NE) and regulates NE transporter (NET) expression. The present study examined the molecular mechanisms involved in regulation of the NET by reserpine using cultured cells. Exposure of rat PC12 cells to reserpine for a period as short as 5min decreased [ H]NE uptake capacity, an effect characterized by a robust decrease in the V of the transport of [ H]NE. As expected, reserpine did not displace the binding of [ H]nisoxetine from the NET in membrane homogenates. The potency of reserpine for reducing [ H]NE uptake was dramatically lower in SK-N-SH cells that have reduced storage capacity for catecholamines. Reserpine had no effect on [ H]NE uptake in HEK-293 cells transfected with the rat NET (293-hNET), cells that lack catecholamine storage vesicles. NET regulation by reserpine was independent of trafficking of the NET from the cell surface. Pre-exposure of cells to inhibitors of several intracellular signaling cascades known to regulate the NET, including Ca /Ca -calmodulin dependent kinase and protein kinases A, C and G, did not affect the ability of reserpine to reduce [ H]NE uptake. Treatment of PC12 cells with the catecholamine depleting agent, α-methyl-p-tyrosine, increased [ H]NE uptake and eliminated the inhibitory effects of reserpine on [ H]NE uptake. Reserpine non-competitively inhibits NET activity through a Ca -independent process that requires catecholamine storage vesicles, revealing a novel pharmacological method to modify NET function. Further characterization of the molecular nature of reserpine\u27s action could lead to the development of alternative therapeutic strategies for treating disorders known to be benefitted by treatment with traditional competitive NET inhibitors

Negative spin Hall magnetoresistance in antiferromagnetic Cr2O3/Ta bilayer at low temperature region

We investigate the observation of negative spin Hall magnetoresistance (SMR) in antiferromagnetic Cr2O3/Ta bilayers at low temperature. The sign of the SMR signals is changed from positive to negative monotonously from 300 K to 50 K. The change of the signs for SMR is related with the competitions between the surface ferromagnetism and bulky antiferromagnetic of Cr2O3. The surface magnetizations of Cr2O3 (0001) is considered to be dominated at higher temperature, while the bulky antiferromagnetics gets to be robust with decreasing of temperature. The slopes of the abnormal Hall curves coincide with the signs of SMR, confirming variational interface magnetism of Cr2O3 at different temperature. From the observed SMR ratio under 3 T, the spin mixing conductance at Cr2O3/Ta interface is estimated to be 1.12*10^14 (ohm^-1*m^-2), which is comparable to that of YIG/Pt structures and our early results of Cr2O3/W. (Appl. Phys. Lett. 110, 262401 (2017)

Ion-Beam Induced Current in High-Resistance Materials

The peculiarities of electric current in high-resistance materials, such as semiconductors or semimetals, irradiated by ion beams are considered. It is shown that after ion--beam irradiation an unusual electric current may arise directed against the applied voltage. Such a negative current is a transient effect appearing at the initial stage of the process. The possibility of using this effect for studying the characteristics of irradiated materials is discussed. A new method for defining the mean projected range of ions is suggested.Comment: 1 file, 7 pages, RevTex, no figure

Robust multilevel optimization of PMSM using design for six sigma

In this paper, a robust optimization method based on design for six sigma (DFSS) is combined to the optimization of a surface mounted permanent synchronous machine (PMSM) by using multilevel genetic algorithm (MLGA). First, MLGA and DFSS are introduced in the robust optimization. Second, by taking into account the tolerances of the motor products, important input parameters could be varied with six sigma distribution and Monte Carlo simulation (MCS) method is used to reduce the calculation cost. Third, to verify the new algorithm, the presented algorithm is applied to the optimization of a PMSM. The results compared with those of traditional GA and MLGA and the discussion of the robust optimization combined with MLGA are presented. © 2011 IEEE