Leakage Flux Adjustment and Flux Field Optimization for Coreless Axial Flux Permanent Magnet Synchronous Machine Based on U-shaped Iron

Wang Xiaoguang,Yin Hao,Liu Cheng,Li Xiaofeng,Zhang Guoguang,Liu Yi,Xu Wei 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5

The rotor leakage flux will cause a lot of eddy current losses in the windings of coreless axial flux permanent magnet synchronous machine (CAFPMSM). This article presents a rotor leakage flux adjustment method for the CAFPMSM based on U-shaped iron, which can also achieve the optimization of the rotor flux field. The U-shaped iron can reduce the leakage flux crosses the winding and improve the spatial harmonic distribution of the air gap field at the same time. Firstly, the basic topology and its operating principle are investigated by using an equivalent magnetic circuit model. And then, the characteristics of the flux field distribution in the winding area are analyzed, and the parameters of the U-shaped iron on the leakage flux path regulation are elaborated and optimized by the three-dimensional finite-element method (3D FEM) analysis. Finally, the comprehensive experimental results show that the leakage flux path of the rotor passes through the U-shaped magnetically conductive block rather than through the windings, the total harmonic distortion (THD) of the air gap flux density waveform can be significantly decreased, and the THD of the back EMF and the eddy current losses are lower than before.

Is the Spillover Hypothesis of Neofunctionalism Functional in an Asian Context? The China–Central Asia and China– Southeast Asia Pipelines in Comparative Perspective

Xiaoguang Wang 경남대학교 극동문제연구소 2022 ASIAN PERSPECTIVE Vol.46 No.1

To secure an oil and gas supply, China has built several types of energy infrastructure near its borders and developed energy cooperation with regional partners based on this infrastructure. However, not all energy cooperation projects develop at an equal pace or are equally successful. This study employs the neofunctionalist spillover hypothesis—one of several key discourses applied to explaining European integration— to account for the difference in regional cooperation between two China-driven energy megaprojects in Asia: the China–Central Asia Pipelines and the China–Southeast Asia Pipelines. After investigation into the so-called spillover hypothesis, including “functional spillover,” “political spillover,” and “cultivated spillover,” the more successful of the two projects was also found to be more significant in terms of its spillover effect. Thus, this article finds that regional cooperation in the Chinese context also supports the spillover hypothesis, which has conventionally been regarded as a Europe-based discourse.

Does the Structural Power of Business Matter in State Capitalism?: Evidence from China's Oil Politics under Xi Jinping

Xiaoguang Wang 인하대학교 국제관계연구소 2019 Pacific Focus Vol.34 No.2

Based on the background of Chinese oil politics under Xi Jinping, this arti-cle studies the“structural power of business”to test the concept within theeconomic system of state capitalism. Many elements of structural powerdiscourse are valid, such as the political influence of business, the role ofinformation-expertise, the role of business competitiveness andfluidity, andthe effect of external factors. However, the dominance and mechanism ofthe structural power of Chinese national oil companies presents differentlybecause of the unique state-business relations in the Chinese oil sector.

Synthesis and Applications of One-Dimensional Porous Nanowire Arrays: A Review

Xiaoguang Wang,Guanshui Ma 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.1

In recent years, particular attention has been drawn to one-dimensional (1D) porous nanowires due to their high surface-to-volume ratios as well as the as-revealed excellent performance in varieties of applications. This review begins with a wide introduction to the as-reported various preparation methods for the typical 1D porous nanowires mainly consisting of template-free method (i.e., chemical etching, chemical vapor deposition, hydrothermal, electrospinning, gassolid reaction, etc.) and template-assisted method (i.e., using hard template and soft template, respectively). Based on the classification of design and preparation strategies, the as-evolved various nonmetallic and metallic 1D nanoporous materials with varied microstructural features have been highlighted, followed by the corresponding description and discussion on their typical applications in catalysis, sensors, rechargeable batteries, solar cells, super-capacitors, water treatment, random lasers and so forth.

Position Sensorless Control of BLDC Motors Based on Global Fast Terminal Sliding Mode Observer

Wang, Xiaoyuan,Fu, Tao,Wang, Xiaoguang The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

The brushless DC motor (BLDCM) has many advantages. As a result, it is widely used in electric vehicle (EV) drive systems. To improve the reliability of the motor control system, a position sensorless control strategy based on a sliding mode observer (SMO) is proposed. The global fast terminal sliding mode observer (GFTSMO) is proposed to enhance the control performance of the SMO control system. The advantages of the linear sliding mode and the nonsingular terminal sliding mode (NTSM) are combined in the control strategy. The convergence speed of the system state is enhanced. The motor commutation point is obtained with the observation of the back EMF, and the instantaneous torque value of the motor is calculated. Therefore, the position sensorless control of the BLDCM is realized. Experimental results show that the proposed control strategy can improve the convergence speed, dynamic characteristics and robustness of the system.

Position Sensorless Control of BLDC Motors Based on Global Fast Terminal Sliding Mode Observer

Xiaoyuan Wang,Tao Fu,Xiaoguang Wang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

The brushless DC motor (BLDCM) has many advantages. As a result, it is widely used in electric vehicle (EV) drive systems. To improve the reliability of the motor control system, a position sensorless control strategy based on a sliding mode observer (SMO) is proposed. The global fast terminal sliding mode observer (GFTSMO) is proposed to enhance the control performance of the SMO control system. The advantages of the linear sliding mode and the nonsingular terminal sliding mode (NTSM) are combined in the control strategy. The convergence speed of the system state is enhanced. The motor commutation point is obtained with the observation of the back EMF, and the instantaneous torque value of the motor is calculated. Therefore, the position sensorless control of the BLDCM is realized. Experimental results show that the proposed control strategy can improve the convergence speed, dynamic characteristics and robustness of the system.

Transcriptional profiles of biliary epithelial cells from rat regenerating liver after partial hepatectomy

Cunshuan Xu,Xiaoguang Chen,Cuifang Chang,Gaiping Wang,Wenbo Wang,Lianxing Zhang,Qiushi Zhu,Lei Wang,Fuchun Zhang 한국유전학회 2012 Genes & Genomics Vol.34 No.3

It has been widely accepted that hepatocytes are critical for liver regeneration (LR), but very little is known about the role of biliary epithelial cells (BECs) in this event, so this study aims to manifest the relevance of BECs with LR. High purity population of BECs was obtained using Percoll gradient centrifugation combined with immunomagnetic-bead separation technique. Transcriptional profiles of BECs from rat regenerating liver after 2/3 hepatectomy were monitored with rat genome 230 2.0 array. Microarray analysis results were evaluated by RT-PCR assays. Of all the genes on the array, 1262 known genes and 1026 unknown genes were related to LR. 79 of 1262 known genes showed a ≥ 20-fold change in expression level, mainly participating in primary metabolism and inflammatory response. In contrast to the regenerating liver,BEC division did not occur at proliferative phase of LR; alterations in nucleic acid, lipid and protein metabolism were significantly different from each other or within the same substance metabolism at different phases; the active signaling pathways in priming phase were mediated mainly by G protein-coupled receptor, small GTPase and Wnt receptor. Transport-related genes showed up-regulated expression mainly in priming and proliferative phases, possibly linked to cell membrane formation and transport function recovery of BECs in the late phase. In brief, comparative analysis of biological activities of BECs and the regenerating liver reveals that bio-logical activities at the cellular level are not always consistent with those at tissue level, suggesting the necessity of cell level investigation on liver regeneration. Finally, expression of BEC markers in hepatocytes may suggest the potential of hepatocytes to transdifferentiate into BEC.

Analysis of Gene Expression Profiles of Liver Stellate Cells During Liver Regeneration in Rats

Xu Cunshuan,Chen Xiaoguang,Chang Cuifang,Wang Gaiping,Wang Wenbo,Zhang Lianxing,Zhu Qiushi,Wang Lei,Zhang Fuchun 한국분자세포생물학회 2011 Molecules and cells Vol.31 No.1

This study performed a large-scale, high-throughput analy-sis of transcriptional profiling of liver stellate cells (LSCs) at the cellular level to investigate changes in the biological activity of LSCs during rat liver regeneration (LR) and the relation of these changes to LR. First, a rat liver regeneration model was established by partial hepatectomy (PH). Stellate cells were isolated in high purity and yield from the regenerating rat liver by Percoll density gradient centrifugation and immunomagnetic bead sorting. The changes in gene expression of LSCs after PH were examined using a rat genome 230 2.0 array composed of 24622 genes. The results indicated that 10241 of the 24622 genes investigated on the array were differentially expressed in LSCs. Of the 10241 genes, 1563 known genes were related to LR, which were grouped into three major gene expression clusters according to three-fold cut-off threshold: the up-regulated gene cluster, the down-regulated gene cluster, and the cluster composed of genes showing complex changes in expression. Additionally, the genes were grouped into those involved in transcription regulation, signal transduction, transport, cellular metabolism, in-flammation and immunity by functional analysis. When gene expression profiles were combined with the results of gene functional analysis, most of the genes involved in cytokine secretion and retinol metabolism in LSCs were significantly enriched in the cluster characterized by decreased expression, whereas genes involved in lipid metabolism were mostly enriched in the cluster showing increased expression. Based on further analysis of genes expressed in a phase-dependent manner during LR, it was suggested that lipid metabolism in LSCs was enhanced in the whole regeneration process, and that immune response and cytokine secretion were impaired during all three regenerative phases.

Surgical Strategy for Skull Base Chordomas : Transnasal Midline Approach or Transcranial Lateral Approach

Wang, Benlin,Li, Qi,Sun, Yang,Tong, Xiaoguang The Korean Neurosurgical Society 2022 Journal of Korean neurosurgical society Vol.65 No.3

Objective : The clinical management paradigm of skull base chordomas is still challenging. Surgical resection plays an important role of affecting the prognosis. Endonasal endoscopic approach (EEA) has gradually become the preferred surgical approach in most cases, but traditional transcranial surgery cannot be completely replaced. This study presents a comparison of the results of the two surgical strategies and a summary of the treatment algorithms for skull base chordomas. Methods : We retrospectively analyzed the surgical outcomes and follow-up data of 48 patients with skull base chordomas diagnosed pathologically who received transnasal midline approaches (TMA) and transcranial lateral approaches (TLA) from 2010 to 2020. Results : Among the 48 patients, 36 cases were adopted TMA and 12 cases were performed with TLA. In terms of gross total resection (GTR) rate, 27.8% in TMA and 16.7% in TLA and with EEA alone it was increased to 38.9%, while 29.7% in primary surgery. In TMA, the cerebrospinal fluid (CSF) leak remains the most common complication (13 cases, 36.1%), other main complications included death, cranial nerve palsy, hypopituitarism, all the comparisons were no statistical significance. The Karnofsky Performance Scale scores in TMA were all better than those in TLA at different time, and the overall survival (OS) and recurrence free survival/progression free survival was just the reverse. Conclusion : The EEA for skull base chordomas resection has improved the GTR rate, but transcranial approach is still an alternative approach. It is necessary to select an appropriate surgical approach based on the location and the pattern of tumor growth in order to obtain the best surgical outcomes.

Clinical Grading System, Surgical Outcomes and Prognostic Analysis of Cranial Base Chordomas

Wang, Benlin,Tian, Fengxuan,Tong, Xiaoguang The Korean Neurosurgical Society 2022 Journal of Korean neurosurgical society Vol.65 No.3

Objective : Cranial base chordomas are rare, but their treatment is challenging. Tumor recurrence is still common despite improvements in microsurgical techniques and postoperative radiotherapy. We retrospectively analyzed the course of treatment, overall survival, and recurrence/progression of chordomas over the past 10 years. Methods : We retrospectively reviewed 50 patients who underwent surgery at Tianjin Huanhu Hospital between 2010 and 2020 and were pathologically diagnosed with chordomas. Tumor resection was performed within the maximum safe range in all patients; the extent of resection was evaluated by imaging; and the incidence of complications, recurrence or progression, and overall survival were assessed. Results : Fifty patients were divided into the low-risk group (LRG) and high-risk group (HRG) based on the cranial chordoma grading system (CCGS). The Karnofsky Performance Scale scores and gross total resection rate of the LRG were significantly higher than those of the HRG (p<0.05). The incidence of complications and mortality in the LRG were lower than those of HRG. The analysis of cumulative survival and cumulative recurrence free survival/progression free survival (RFS/PFS) showed no statistical differences in the extent of resection for survival, recurrence, or progression. Univariate and multivariate analyses showed that Ki-67 was significantly associated with tumor recurrence and was an independent hazard factor (p=0.02). Conclusion : The CCGS can help neurosurgeons anticipate surgical outcomes. Pathological results are important in evaluating the possibility of tumor recurrence, and postoperative radiotherapy improves overall survival and RFS/PFS.