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Fully Decoupled Branch Energy Balancing Control Method for Modular Multilevel Matrix Converter Based on Sequence Circulating Components

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 235-247页

作者： Zexin Zhao Weijiang Chen Zhichang Yang Guoliang Zhao Bin Han Yunfei Xu Nianwen Xiang Shulai Wang China Electric Power Research Institute Beijing 100192China State Grid Corporation of China Beijing 100031China State Grid Smart Grid Research Institute Beijing 102209China State Key Laboratory of Advanced Power Transmission technology Global Energy Interconnection Research InstituteBeijing 102211China Hefei university of technology Hefei 230009China

The modular multilevel matrix converter(M3C)is a potential frequency converter for low-frequency AC transmission.However,capacitor voltage control of high-voltage and largecapacity M3C is more difficult,especially for voltage balancing between branches.To solve this problem,this paper defines sequence circulating components and theoretically analyzes the influence mechanism of different sequence circulating components on branch capacitor voltage.A fully decoupled branch energy balancing control method based on four groups of sequence circulating components is proposed.This method can control capacitor voltages of nine branches in horizontal,vertical and diagonal directions.Considering influences of both circulating current and voltage,a cross decoupled control is designed to improve control precision.Simulation results are taken from a low-frequency transmission system based on PSCAD/EMTDC,and effectiveness and precision of the proposed branch energy balancing control method are verified in the case of nonuniform parameters and an unbalanced power system.

关键词： Branch energy balancing control decoupled control low-frequency AC transmission modular multilevel matrix converter(M3C) sequence circulating components

Polarization engineering in porous organic polymers for charge separation efficiency and its applications in photocatalytic aerobic oxidations

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Science China Chemistry 2024年第3期67卷 1000-1007页

作者： Kun Wu Pei-Wen Cheng Xin-Yi Liu Ji Zheng Xiao-Wei Zhu Mo Xie Puxin Weng Weigang Lu Dan Li College of Chemistry and Materials Science Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and ApplicationsJinan UniversityGuangzhou 510632China Guangdong Rare Earth Photofunctional Materials Engineering technology Research Center School of Chemistry and EnvironmentJiaying UniversityMeizhou 514015China

Photocatalytic aerobic oxidation reactions are largely governed by the efficiency of charge separation and subsequent reactive oxygen species(ROS) generation. Herein, we report a polarization engineering strategy to promote the charge separation and ROS generation efficiency by substituting the benzene unit with furan/thiophene in porous organic polymers(POPs). Benefiting from the extent of local polarization, the thiophene-containing POP(JNU-218) exhibits the best photocatalytic performance in aerobic oxidation reactions, with a yield much higher than those for the furan-containing POP(JNU-217) and the benzenecontaining POP(JNU-216). Experimental studies and theoretical calculations reveal that the increase of local polarization can indeed reduce the exciton binding energy, and therefore facilitate the separation of electron-hole pairs. This work demonstrates a viable strategy to tune charge separation and ROS generation efficiency by modulating the dipole moments of the building blocks in porous polymeric organic semiconductors.

关键词： porous organic polymer local polarization photocatalytic aerobic oxidation charge separation reactive oxygen species exciton binding energy

Stress Concentration Effect in Interface Between Conductor and Epoxy Resin in Coaxial Components of Power Equipment

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 412-420页

作者： Chuang Wang Kang Lei Qing Sun Hui Li Jiawei Zhang Lang Zhao Zongren Peng School of Electrical Engineering Xi’an University of TechnologyXi’an 710054China Xi’an Power Supply Company State Grid Shaanxi Electric Power CompanyXi’an 710032China State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’an 710049China

The spacer used in gas insulated switchgear(GIS)plays a vital role in its safe operation.The mismatch of mechanical properties between conductor and insulating material in spacers results in stress concentration at the interface between them.During a hydrostatic test,mechanical damages are often initiated from the interface.In this paper,the stress between aluminum conductors and epoxy resin is studied by using a simplified coaxial structure specimen.The measurement system and finite element simulation are used to explore the generation of stress and strain during curing and shrinkage.The real-time measurement of strain at the interface shows that the residual strain in the entire process is primarily generated during the cooling stage.Consequently,the temperature and stress/strain distribution at the interface during the cooling stage are further studied,and combined with experiments and simulations.The consistency between the finite element simulation and the experimental measurement results verifies the validity of the simulation method used.The results show that the maximum of the first principal stress generated during the cooling stage of the production process is concentrated on the upper and lower edges of the interface which is critical to the impact of the production quality of the spacer.

关键词： Epoxy resin GIS interface stress/strain distribution

Ferric ion-triggered surface oxidation of galena for efficient chalcopyrite-galena separation

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 261-267页

作者： Qiancheng Zhang Limin Zhang Feng Jiang Honghu Tang Li Wang Wei Sun School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Engineering Research Center of Ministry of Education for Carbon Emission Reduction in Metal Resource Exploitation and Utilization Changsha 410083China School of Resource and Environment Hunan University of Technology and BusinessChangsha 410083China

The efficient separation of chalcopyrite(CuFeS2)and galena(PbS)is essential for optimal resource utilization.However,find-ing a selective depressant that is environmentally friendly and cost effective remains a challenge.Through various techniques,such as mi-croflotation tests,Fourier transform infrared spectroscopy,scanning electron microscopy(SEM)observation,X-ray photoelectron spec-troscopy(XPS),and Raman spectroscopy measurements,this study explored the use of ferric ions(Fe^(3+))as a selective depressant for ga-lena.The results of flotation tests revealed the impressive selective inhibition capabilities of Fe^(3+)when used alone.Surface analysis showed that Fe^(3+)significantly reduced the adsorption of isopropyl ethyl thionocarbamate(IPETC)on the galena surface while having a minimal impact on chalcopyrite.Further analysis using SEM,XPS,and Raman spectra revealed that Fe^(3+)can oxidize lead sulfide to form compact lead sulfate nanoparticles on the galena surface,effectively depressing IPETC adsorption and increasing surface hydrophilicity.These findings provide a promising solution for the efficient and environmentally responsible separation of chalcopyrite and galena.

关键词： galena chalcopyrite ferric ions flotation separation surface oxidation

Direct 4D printing of functionally graded hydrogel networks for biodegradable,untethered,and multimorphic soft robots

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International Journal of Extreme Manufacturing 2024年第2期6卷 407-416页

作者： Soo Young Cho Dong Hae Ho Sae Byeok Jo Jeong Ho Cho Department of Chemical and Biomolecular Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Mechanical Engineering Virginia TechBlacksburgVA 24061United States of America School of Chemical Engineering Sungkyunkwan UniversitySuwon 16419Republic of Korea SKKU Institute of Energy Science and technology(SIEST) Sungkyunkwan UniversitySuwon 16419Republic of Korea

Recent advances in functionally graded additive manufacturing(FGAM)technology have enabled the seamless hybridization of multiple functionalities in a single structure.Soft robotics can become one of the largest beneficiaries of these advances,through the design of a facile four-dimensional(4D)FGAM process that can grant an intelligent stimuli-responsive mechanical functionality to the printed objects.Herein,we present a simple binder jetting approach for the 4D printing of functionally graded porous multi-materials(FGMM)by introducing rationally designed graded multiphase feeder beds.Compositionally graded cross-linking agents gradually form stable porous network structures within aqueous polymer particles,enabling programmable hygroscopic deformation without complex mechanical designs.Furthermore,a systematic bed design incorporating additional functional agents enables a multi-stimuli-responsive and untethered soft robot with stark stimulus selectivity.The biodegradability of the proposed 4D-printed soft robot further ensures the sustainability of our approach,with immediate degradation rates of 96.6%within 72 h.The proposed 4D printing concept for FGMMs can create new opportunities for intelligent and sustainable additive manufacturing in soft robotics.

关键词： intelligent and sustainable additive manufacturing multi-material four-dimensional printing untethered soft robot multi-stimuli-responsive soft robot biodegradable soft robotics

Low Loss and Low EMI Noise Trench IGBT with Shallow Emitter Trench Controlled P-Type Dummy Region

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Chinese Journal of Electronics 2024年第2期33卷 326-335页

作者： Jinping ZHANG Xiaofeng LI Rongrong ZHU Kang WANG Bo ZHANG State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China (UESTC) Institute of Electronic and Information Engineering of UESTC in Guangdong

A novel trench insulated gate bipolar transistor（TIGBT） with a shallow emitter trench controlled P-type dummy region（STCP-TIGBT） is proposed.Compared with the conventional TIGBT with floating P-type dummy region（CFP-TIGBT） and TIGBT with floating P-type dummy region and normally on hole path（HFPTIGBT）,the proposed STCP structure not only speeds up the extraction of excessive holes in the turn-off process but also reduces the Miller plateau charge(Qgc).Therefore,both the power loss and electromagnetic interference（EMI） noise are significantly reduced.Simulation results show that the Qgcof the proposed device is only 501 nC/cm2,which is reduced by 58.5% and 26.4% when compared to the CFP-TIGBT and HFP-TIGBT,respectively.At same on-state voltage drop(Vceon) of 1.02 V,the turn-off loss(Eoff) of the proposed device is 13.49 mJ/cm2,which is 64.6%and 67.6% less than those of the CFP-TIGBT and HFP-TIGBT,respectively.Moreover,the reverse recovery dVak/dt of the freewheeling diode at same turn-on loss(Eon) of 31.8 mJ/cm2for the proposed STCP-TIGBT is only 2.15 kV/μs,which is reduced by 91.3% and 57.2% when compared to 24.69 kV/μs and 5.02 kV/μs for the CFP-TIGBT and HFPTIGBT,respectively.The reduced dV/dt significantly suppresses the electromagnetic interference noise generated by the proposed device.

关键词： Trench insulated gate bipolar transistor On-state voltage drop Turn-off loss Turn-on loss Electromagnetic interference noise Shallow emitter trench P-type dummy region

Investigating the interaction between umami peptides and umami receptor T1R1/T1R3-VFT: a computational approach

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Food Science and Human Wellness 2024年

作者： Hengli Meng Zhiyong Cui Yingqiu Li Yanyang Yu Shui Jiang Yuan Liu Department of Food Science & technology School of Agriculture and Biology Shanghai Shanghai Jiao Tong university Secondary College of Cereals and Tourism Guangxi Vocational College of technology and Business

The study of ligand-receptor interactions is of great significance in food flavor perception. In this study， a computer simulation method was used to investigate the mechanism of interaction between umami peptides and T1R1/T1R3-VFT receptor. The binding site， conformational changes， and binding free energy between umami peptides and T1R1/T1R3-VFT were analyzed through molecular modeling， molecular docking， and molecular dynamics simulations. The receptor model constructed using AlphaFold2 has the best rationality. The molecular docking results showed that umami peptides primarily bound to T1R1-VFT through hydrogen bonding， with key binding residues such as 149THR， 151ARG， and 108ASP. The binding of umami peptides led to a more stable complex system， and the positively charged amino acids contributed positively to the overall binding free energy. This study provides theoretical support for the development of a better understanding of the interaction between umami substances and the umami receptor.

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Chronic infectious unilateral giant thyroid cyst related to diabetes mellitus:A case report

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World Journal of Clinical Cases 2024年第8期12卷 1497-1503页

作者： Jiang-Bo Liu Shi-Lei Zhang Wen-Long Jiang Hai-Kuan Sun Hao-Chen Yang Department of Thyroid and Breast Surgery The First Affiliated HospitalCollege of Clinical MedicineHenan University of Science and TechnologyLuoyang 471000Henan ProvinceChina Clinical Medicine School The First Clinical CollegeChongqing Medical UniversityChongqing 400016China

BACKGROUND Patients rarely develop complicated infections in thyroid cysts.Here,we describe a patient with chronic infected unilateral giant thyroid cyst related to diabetes mellitus(DM).CASE SUMMARY A 66-year-old male was admitted due to an evident neck lump for 5 d after approximately 40 years of gradually progressive neck mass and 7 years of DM.Doppler ultrasound and computed tomography scan showed a giant lump in the left thyroid gland lobe.He was diagnosed with a large thyroid nodule complicated by tracheal dislocation and had surgical indications.Surgical exploration revealed evident inflammatory edema and exudation between the left anterior neck muscles,the nodule and glandular tissue.Fortunately,inflammatory lesions did not affect major neck vessels.Finally,a left partial thyroidectomy was performed.Macroscopic observation showed that the cystic thyroid mass consisted of extensive cystic wall calcification and was rich in massive rough sand-like calculi content and purulent matter.Postoperative pathology confirmed benign thyroid cyst with chronic infection.CONCLUSION The progression of this chronic infectious unilateral giant thyroid cyst may have been related to DM,and identifying blood vessels involvement can prevent serious complications during operation.

关键词： Thyroid nodule Infection Diabetes mellitus Surgery Case report

Slope stability of reclaimed coal mines through a new water filling index

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 828-839页

作者： Antonios Mikroutsikos Alexandros I.Theocharis Nikolaos C.Koukouzas Ioannis E.Zevgolis Chemical Process&Energy Resources Institute Centre for Research&Technology HellasAthensGreece School of Mining and Metallurgical Engineering National Technical University of AthensAthensGreece

A common reclamation practice for closed coal surface mines is filling them with water to form pit lakes.The creation and sustainability of these lakes are significantly affected by the stability of the corresponding slopes.The present study provides a general framework for analyzing the water filling’s effect on slope stability based on a new water filling index,which can indirectly consider the factors affecting the process and efficiently quantify the filling speed’s influence.The assumptions of the proposed approach are thoroughly discussed,and the range of the water filling index is identified.Furthermore,the safety factor is calculated using the finite element method with the shear strength reduction technique during the filling process for various conditions(soil properties,slope geometry,hydraulic conditions,and water filling speed).Results are presented as normalized stability charts for practical use.During the water filling,the stability gradually decreases until the reservoir reaches a critical level of 10%e40%of the total height;it then increases to even more stable conditions than the initial one.Overall,the present analysis allows for the preliminary stability evaluation of a coal mine during the formation of a pit lake and the appropriate quantification of the water filling’s effect.

关键词： Post-coal era Open-pit flooding Stability charts Critical level