A Fast Classification Method of Faults in Power Electronic Circuits Based on Support Vector Machines

Fault detection and location are important and front-end tasks in assuring the reliability of power electronic circuits. In essence, both tasks can be considered as the classification problem. This paper presents a fast fault classification method for power electronic circuits by using the support vector machine (SVM) as a classifier and the wavelet transform as a feature extraction technique. Using one-against-rest SVM and one-against-one SVM are two general approaches to fault classification in power electronic circuits. However, these methods have a high computational complexity, therefore in this design we employ a directed acyclic graph (DAG) SVM to implement the fault classification. The DAG SVM is close to the one-against-one SVM regarding its classification performance, but it is much faster. Moreover, in the presented approach, the DAG SVM is improved by introducing the method of Knearest neighbours to reduce some computations, so that the classification time can be further reduced. A rectifier and an inverter are demonstrated to prove effectiveness of the presented design

On optimizing the aerodynamic load acting on the turbine shaft of PMSG-based direct-drive wind energy conversion system

The blade’s rotational sampling to the spatial distributed wind velocities will induce 3P oscillating aerodynamic torque during the wind energy generation process. This causes the turbine drive-train bare high aerodynamic load because the generator is driven by this aerodynamic torque through it. Moreover, the system inherent resonant mode will also be induced by the aerodynamic load, causing fatal damage to the whole system. To damp the serious aerodynamic load of the PMSG-based direct- drive wind energy conversation system (WECS), a new power control strategy with damping injection is proposed in this paper. The proposed method is realized by adding a compensation torque, which is proportional to the small-signal value of the generator speed, into the system torque control loop. Both the aerodynamic load and the system inherent resonant mode can be well damped if the proposed method had been adopted. Theoretic analysis is verified by experimental results performed by a 10kW WECS established in the laboratory.Accepted versio

Timing, tectonic implications and genesis of gold mineralization in the Xincheng gold deposit, China: C–H–O isotopes, pyrite Rb–Sr and zircon fission track thermochronometry

The Xincheng gold deposit located at the northwestern edge of the Jiaodong Peninsula in the North China Craton has a reserve of ~ 96 t Au and is among the largest in the Jiaodong gold province. Here, disseminated- and stockwork-style ores are hosted in Mesozoic granitoids. The mineralization and alteration are largely controlled by the regional Jiaojia fault. The C–H–O isotope values in the ores indicate that the ore-forming fluids were derived mainly from magmatic sources. New Rb–Sr geochronological data on hydrothermal pyrite from the Xincheng deposit presented in this study indicate that the main gold mineralization occurred between 126 Ma and 122 Ma. The zircon fission track of convergent ages and decomposed divergent ages from the ores and altered rocks show four groups of ages: ~ 135 Ma, ~ 124 Ma, 96–75 Ma, and 66–52 Ma. The ~ 135 Ma is related to the exhumation and cooling of the Linglong granitoids. The ~ 124 Ma is considered to represent the principal stage of gold mineralization, and is consistent with the pyrite Rb–Sr ages. The younger ages of 96–75 Ma and 66–52 Ma resulted from subsequent annealing caused by later tectonic activity. The timing of gold mineralization in the Xincheng gold deposit broadly coincides with the switch in stress field in eastern China from extension to transpression, resulting from the change in subduction direction of the Pacific Plate from NE–SW to NW–SE, and marked by extension-related voluminous magmatism associated with the Cretaceous giant igneous event in eastern China

Cloning and expression analysis of <i>BmYki</i> gene in silkworm, <i>Bombyx mori</i>

<div><p>The transcriptional coactivator Yorkie(Yki), is a critical downstream effector of the Hippo(Hpo) signaling pathway that controls organ size through the regulation of cell proliferation and apoptosis. During the past ten years the biological function of Yki has been studied extensively in <i>Drosophila</i> and a few other insects, however, little is known about it in the silkworm, <i>Bombyx mori</i>, a major research model of lepidopteran insect. Here, we describe the isolation, characterization and expression of the <i>B</i>. <i>mori</i> Yki ortholog, BmYki. The coding sequence of the <i>BmYki</i> was 1314 bp in length, encoding a protein of 437 amino acids containing two conserved WW domains. <i>BmYki</i> transcripts were ubiquitous but not abundant in all detected tissues and developmental stages. Comparatively, it was expressed at pretty high level in silk glands and at the stage of fifth-instar day-3 larvae. Overexpression of <i>BmYki</i> in cultured <i>B</i>. <i>mori</i> embryonic cells significantly promoted transcription of genes associated with cell proliferation and apoptosis, indicating that <i>BmYki</i> functions in the regulation of organ growth-related biological processes. Interestingly, transcription of silk protein-coding genes and transcription factors regulating the synthesis of silk proteins was downregulated remarkably, suggesting that <i>BmYki</i> was involved in the regulation of silk protein synthesis. This study provides new insights into the role of <i>BmYki</i> in Hpo pathway regulation in silkworm.</p></div

Expression profiles of <i>BmYki</i> in <i>B</i>. <i>mori</i>.

<p>(A)mRNA levels of <i>BmYki</i> in different tissues of <i>Dazao</i> strain. HD(head); EP(epidermis); FB (fat body); TR (trachea); HA(hemocyte); MG(midgut); MT(malpighian tubule); TE(testis); OV(ovary); ASG(anterior silk gland); MSG(middle silk gland); PSG(posterior silk gland); SG (total silk gland). (B)mRNA levels of <i>BmYki</i> at different developmental stages of <i>Dazao</i> strain. 1L-1, 2L-1, 3L-1, and 4L-1(day-1 of the first, second, third, and fourth larval instar); 5L-1, 5L-3, 5L-5, and 5L-7(day-1, 3, 5, and 7 of the fifth instar), P-1(day-1 of the pupal stage), MM-1 and FM-1(day-1 of the male and female moth). Relative mRNA levels of <i>BmYki</i> against <i>sw22934</i> are shown. Error bars represent mean ±SD of three samples.</p