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Chinese Journal of Mechanical Engineering 2021年第6期34卷 224-239页

作者： Sai Guo Guanhui Ren Bi Zhang Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhenGuangdongChina State Key Laboratory of Ultra-precision Machining technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityKowloonHong KongChina

New materials and manufacturing technologies require applicable non-destructive techniques for quality assurance so as to achieve better *** study comprehensively investigated the effect of influencing factors includ-ing excitation frequency,lift-off distance,defect depth and size,residual heat,and surface roughness on the defect EC signals of an Inconel 738LC alloy produced by selective laser melting(SLM).The experimental investigations recorded the impedance amplitude and phase angle of EC signals for each defect to explore the feasibility of detecting sub-surface defects by merely analyzing these two key ***,this study revealed preliminary qualitative and roughly quantitative relationships between influencing factors and corresponding EC signals,which provided a prac-tical reference on how to quantitively inspect subsurface defects using eddy current testing(ECT)on SLMed parts,and also made solid progress toward on-line ECT in additive/subtractive hybrid manufacturing(ASHM)for fabricating SLMed parts with enhanced quality and better performance.

关键词： Eddy current testing Subsurface defect Additive/subtractive hybrid manufacturing Selective laser melting Inconel 738LC alloy

Research on Iron Loss of Switched Reluctance Starter/Generator for Energy Storage

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Protection and Control of Modern Power Systems 2024年第4期9卷 147-159页

作者： Hao Chen Xing Wang Yongqiang Liu Vuong Dang Quoc Wenju Yan Muhammad Saqib Antonino Musolino Guanjun Wang Yong Qi Ali Asghar Memon Alexandros G.Paspatis the shenzhen Research Institute China University of Mining and TechnologyShenzhen 515100China the School of Electrical Engineering China University of Mining and TechnologyXuzhou 221116China Xinjiang Institute of Engineering Urumqi 830000China the International Joint Research Center of Central and Eastern European Countries on New Energy EV technology and Equipment Xuzhou 221008China the International Cooperation Joint Laboratory of New Energy Power Generation and EVs of Jiangsu Province Colleges and Universities Xuzhou 221008China the Xuzhou Key Laboratory of New Energy EV technology and Equipment Xuzhou 221008China the the School of Electrical Engineering China University of Mining and Tech-nologyXuzhou 221116China the Laboratory of High Performance Electric Machines(HiPems) Hanoi VN 10000Viet Nam the University of Engineering and technology Lahore 54890Pakistan the Department of Energy Pisa Uni-versity of PisaPisa IT 56126Italy the Wuxi Inspection and Testing Certification Research Institute Wuxi 214000China the Nanjing University of science&Tech-nology Nanjing 210094China the Mehran University of Engi-neering&technology Jamshoro PK 76062Sindh the National Technical University of Athens Zografou GR 15780Attica

In order to better realize the energy recovery and storage of hybrid EVs(HEVs),a switched reluctance starter/generator(SRS/G)with both starting and power generation functions is investigated in this ***,the iron loss of SRS/G is mainly studied to reduce the motor loss and improve the power generation ***,the energy storage of hybrid EVs can be effectively ***,a magnetic flux density(MFD)waveforms solution method is proposed to solve the difficulty in calculating the iron loss of the SRS/*** with the commonly used finite element method,the proposed solution method has the advantages of simple,fast and small computational ***,considering the different operating conditions of SRS/G,the iron loss models for both the time-domain and frequency-domain are *** addition,the calculation formula of the variable coefficient Bertotti three-term loss separation is *** the hysteresis loss coefficient,the Steinmetz coefficient and the stray loss coefficient are respectively fitted by the Fourier fitting *** method is also applied to solve the iron loss of SRS/***,through an experimental verification,it is indicated that the development of proposed method has high accuracy.

关键词： Switched reluctance starter/generator energy storage iron loss finite element method magnetic flux density(MFD)

A novel digital control strategy of three-phase shunt active power filter under non-ideal mains voltages

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Journal of Central South University 2011年第6期18卷 2021-2030页

作者：胡志坤陈志文华长春王会海丁家峰 School of Physics science and technology Central South University Institute of Electrical Engineering Yanshan University

A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.

关键词： non-ideal mains voltage deadbeat control fundamental positive sequence active current shunt active power filter

Accurate measurement and influence on device reliability of defect density of a light-emitting diode

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Chinese Physics B 2013年第10期22卷 412-416页

作者：郭祖强钱可元 Key Laboratory of Information science and technology Graduate School of Tsinghua University at Shenzhen

A method of accurately measuring the defect density of a high-power light-emitting diode （LED） is proposed. The method is based on measuring the number of emitting photons in the magnitude of 105 under the injection current as weak as nA and calculating the non-radiative recombination coefficient which is related to defect density. Defect density is obtained with the self-developed measurement system, and it is demonstrated that defect density has an important influence on LED optical properties like luminous flux and internal quantum efficiency （IQE）. At the same time, a batch of GaN-based LEDs with the chip size of 1 minx 1 mm are selected to conduct the accelerated aging tests lasting for 1000 hours. The results show that defect density exhibits a greater variation and is more sensitive to LED reliability than luminous flux during aging tests. Based on these results, it is concluded that for the GaN-based LED with a chip size of 1 mm ~ I mm, if its defect density is over 1017/cm3, the LED device performance suffers a serious deterioration, and finally fails.

关键词： accurate measurement defect density LED reliability

Total Synthesis and Biological Evaluation of Wewakazole

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Chemical Research in Chinese Universities 2017年第6期33卷 890-894页

作者： LONG Bohua ZHANG Jingzhao WANG Xueyan TANG Xudong WU Zhengzhi The Fourth People's Hospital ofshenzhen Shenzhen 518033 P. R. China shenzhen Institute of Geriatncs Shenzhen 518020 P. R. China The Second People's Hospital of shenzhen Shenzhen 518035 P. R. China Key Lab for New Drug Research of TCM and shenzhen Branch State R&D Centre for Viro-Biotech Research Institute of Tsinghua University in Shenzhen Shenzhen 518057 P. R. China

The total synthesis of Wewakazole was achieved on a gram scale, unambiguously confirming its structure. Three different substituted oxazoles present in this natural product were prepared efficiently. Biological evalua... 详细信息

关键词： Wewakazole Total synthesis Biological evaluation

Computed tomography combined with gastroscopy for assessment of pancreatic segmental portal hypertension

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World Journal of Clinical Cases 2022年第24期10卷 8568-8577页

作者： Yu-Li Wang Han-Wen Zhang Fan Lin Department of Radiology The First Affiliated Hospital of Shenzhen UniversityHealth Science CenterShenzhen Second People’s HospitalShenzhen 518035Guangdong ProvinceChina

BACKGROUND Pancreatic segmental portal hypertension(PSPH) is the only type of portal hypertension that can be completely cured. However, it can easily cause varicose veins in the esophagus and stomach and hemorrhage in the digestive *** To explore the application of computed tomography(CT) to examine the characteristics of PSPH and assess the risk *** This was a retrospective analysis of CT images of 22 patients diagnosed with PSPH at our center. Spearman correlation analysis was performed using the range of esophageal and gastric varices(measured by the vertical gastric wall), the ratio of the width of the splenic portal vein to that of the compression site(S/C ratio), the degree of splenomegaly, and the stage determined by gastroscopy. This study examined whether patients experienced gastrointestinal bleeding within 2 wk and combined CT and gastroscopy to explore the connection between bleeding and CT *** The range of esophageal and gastric varices showed the best correlation in the diagnosis of PSPH(P < 0.001), and the S/C ratio(P = 0.007) was correlated with the degree of splenomegaly(P = 0.021) and PSPH(P < 0.05). This study revealed that male patients were more likely than females to progress to grade 2 or grade 3 as determined by gastroscopy. CT demonstrated excellent performance, with an area under the curve of *** CT can be used to effectively analyze the imaging signs of PSPH, and CT combined with gastroscopy can effectively predict the risk level of gastrointestinal bleeding.

关键词： Computed tomography Pancreatic segmental portal hypertension esophageal and gastric varices Gastrointestinal bleeding Curable portal hypertension

Value of contrast-enhanced ultrasound combined with elastography in evaluating cervical lymph node metastasis in papillary thyroid carcinoma

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World Journal of Clinical Cases 2019年第1期7卷 49-57页

作者： Wei Jiang Hong-Yan Wei Hai-Yan Zhang Qiu-Luan Zhuo Department of Ultrasound Shenzhen Nanshan District People’s Hospital

BACKGROUND Cervical lymph node metastasis in papillary thyroid carcinoma(PTC) affects the treatment and prognosis of patients. Ultrasound is a common imaging method for detecting cervical lymph nodes in PTC patients; however, it is not accurate in determining lymph node *** To evaluate the value of contrast-enhanced ultrasound combined with elastography in evaluating cervical lymph node metastasis in *** A total of 94 patients with PTC were recruited. According to pathological results,lymph nodes were divided into two groups: metastatic group(n = 50) and reactive group(n = 63). The routine ultrasound findings, contrast-enhanced ultrasound and elastography data were recorded and compared. Logistic regression was used to generate predictive probability distributions for the diagnosis of lymph node metastasis with different indicators. Receiver operating characteristic curve analysis was used to test the efficacy of contrast-enhanced ultrasound combined with elastography based on routine ultrasound in evaluating PTC cervical lymph node *** The ratio of long diameter/short diameter(L/S) ≤ 2, irregular marginal morphology, missing lymphatic portal, peripheral or mixed blood flow distribution, peak intensity(PI), non-uniform contrast distribution and elasticity score in the metastatic group were significantly higher than those in the reactive group(P < 0.05). L/S ratio, missing lymphatic portal, PI and elasticity score had a significant influence on the occurrence of PTC cervical lymph node metastasis(P< 0.05). Furthermore, the area under the curve(AUC) for lymph node metastasis diagnosed using the combination of PI ratio, elasticity score, missing lymphatic portal and LS was 0.936, which was significantly higher than the AUC for PI ratio alone. The difference was statistically significant(P < 0.05). The fitting equation for the combined diagnosis was logit(P) =-12.341 + 1.482 × L/S ratio + 3.529 ×missing lymphatic portal + 0.392 × PI + 3

关键词： Contrast-enhanced ultrasound Elastography Papillary thyroid cancer Cervical lymph node metastasis

Analysis of third and one-third harmonic generation in lossy waveguides

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Chinese Physics B 2019年第6期28卷 209-212页

作者： Jianyu Zhang Yunxu Sun Qinghai Song Department of Electronic and Information Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China Department of science Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

A comprehensive study on the requirements for the highly efficient third harmonic generation(THG) and its inverse process, one-third harmonic generation(OTHG), in lossy waveguides is proposed. The field intensity restrictions for both THG and OTHG caused by loss are demonstrated. The effective relative phase ranges, supporting the positive growth of signal fields of THG and OTHG are shrunken by the loss. Furthermore, it turns out that the effective relative phase ranges depend on the intensities of the interacting fields. At last, a modified definition of coherent length in loss situation, which evaluates the phase matching degree more precisely, is proposed by incorporating the shrunken relative phase range and the nonlinear phase mismatch. These theoretical analysis are valuable for guiding the experimental designs for highly efficient THG and OTHG.

关键词： coupled mode theory third harmonic generation one-third harmonic generation loss effects

Enhanced Surface Mechanical Properties and Microstructure Evolution of Commercial Pure Titanium Under Electropulsing-Assisted Ultrasonic Surface Rolling Process

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Acta Metallurgica Sinica(English Letters) 2018年第12期31卷 1272-1280页

作者： Yong-Da Ye Xiao-Pei Li Zhi-Yan Sun Hai-Bo Wang Guo-Yi Tang Advanced Materials Institute Graduate School at ShenzhenTsinghua University School of Materials science and Engineering Tsinghua University

The effects of electropulsing-assisted ultrasonic surface rolling process on surface mechanical properties andmicrostructure evolution of commercial pure titanium were investigated. It was found that the surface mechanical prop-erties were significantly enhanced compared to traditional ultrasonic surface rolling process （USRP）, leading to smallersurface roughness and smoother morphology with fewer cracks and defects. Moreover, surface strengthened layer wasremarkably enhanced with deeper severe plastic deformation layer and higher surface hardness. Remarkable enhancementsof surface mechanical properties may be related to the gradient refined microstructure, the enhanced severe plasticdeformation layer and the accelerated formation of sub-boundaries and twins induced by coupling effects of USRP andelectropulsing. The primary intrinsic reasons for these improvements may be attributed to the thermal and athermal effectscaused by electropulsing treatment, which would accelerate dislocation mobility and atom diffusion.

关键词： Electropulsing-assisted ultrasonic surface rolling process (EP-USRP) Commercial pure titanium Roughness Hardness Microstructure evolution

Induction of Endoplasmic Reticulum Stress by Cadmium and Its Regulation on Nrf2 Signaling Pathway in Kidneys of Rats

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Biomedical and Environmental sciences 2019年第1期32卷 1-10页

作者： CHEN Zhi Jian CHEN Jia Xing WU Li Kang LI Bi Yun TIAN Ya Feng XIAN Min HUANG Zi Pei YU Ri An School of Public Health Guangdong Pharmaceutical University Bao'an Center for Disease Control and Prevention of shenzhen

Objective This study was conducted to investigate the regulation of endoplasmic reticulum stress on Nrf2 signaling pathway in the kidneys of rats. Methods Rats were divided into twelve groups of six animals each. Some groups were pre-administered with bacitracin or tauroursodeoxycholic acid(TUDCA), and all of them were treated with 5-20 μmol/kg cadmium(Cd) for 48 h. The oxidative stress levels were analyzed using kits. The mRNA and protein expression levels of endoplasmic reticulum stress-related factors and Nrf2 signaling pathway-related factors were determined using RT-PCR and western blot. Results Cd exposure resulted in oxidative stress in the kidneys of rats and upregulated the expression of endoplasmic reticulum stress(ERS)-related factors and Nrf2 signaling pathway-related factors, especially at doses of 10 and 20 μmol/kg Cd, and the expression changes were particularly obvious. Moreover, after pretreatment with bacitracin, Cd upregulated the expression of ERS-related factors to a certain extent and, at higher doses, increased the mRNA expression of Nrf2. After pretreatment with TUDCA, Cd reduced the level of ERS to a certain extent; however, at these doses, there were no significant changes in the expression of Nrf2. Conclusion Cadmium can result in ERS and oxidative stress in the kidneys of rats, activate Nrf2, and upregulate the transcriptional expression of phase II detoxification enzymes under these experimental conditions. ERS has a positive regulation effect on Nrf2 signaling pathway but has little effect on the negative regulation of Nrf2 signaling pathway in cadmium toxicity.

关键词： Cadmium Endoplasmic reticulum stress PERK Nrf2 Kidney Rat