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Coordinated Control of Parallel Three-phase four-wire Converters in Autonomous AC Microgrids

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CSEE Journal of Power and Energy Systems 2024年第5期10卷 2065-2078页

作者： rui Liu Li guo Xialin Li Key Laboratory of Smart Grid of Ministry of Education Tianjin UniversityTianjin 300072China

The coordinated control of parallel three-phase fourwire converters in autonomous AC microgrids is investigated in this ***,based on droop control,virtual impedance is inserted in positive-,negative-and zero-sequences to enhance system damping and imbalance power ***,to facilitate virtual impedance design,small signal models of the three-sequence equivalent circuits are established *** indexes are proposed to comprehensively evaluate the impact of sequence virtual impedance on current sharing accuracy,voltage quality at the point of common coupling(PCC)and system *** addition,constraint of DClink voltage is also considered to avoid over modulation when subjected to unbalanced ***,to address the PCC voltage degradation resulting from virtual impedance,a voltage imbalance compensation method,based on low-bandwidth communication,is ***,simulation and experimental results are provided to verify the correctness of the theory model,indicating that the proposed method can achieve PCC voltage restoration while guaranteeing the current sharing accuracy with desirable dynamics.

关键词： AC microgrids sequence virtual impedance three-phase four-wire(3P4W)converter voltage imbalance compensation

Dual-salt poly(tetrahydrofuran) electrolyte enables quasi-solid-state lithium metal batteries to operate at -30 ℃

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Journal of Energy Chemistry 2024年第9期96卷 456-463页

作者： Zhiyong Li Zhuo Li rui Yu Xin guo School of Materials Science and Engineering State Key Laboratory of Material Processing and Die&Mould TechnologyHuazhong University of Science and TechnologyWuhan 430074HubeiChina The State Key Laboratory of Refractories and Metallurgy and Institute of Advanced Materials and Nanotechnology Wuhan University of Science and TechnologyWuhan 430081HubeiChina

The stable operation of solid-state lithium metal batteries at low temperatures is plagued by severe restrictions from inferior electrolyte-electrode interface compatibility and increased energy barrier for Li^(+)***,we prepare a dual-salt poly(tetrahydrofuran)-based electrolyte consisting of lithium hexafluorophosphate and lithium difluoro(oxalato)borate(LiDfOB).The Li-salt anions(DfOB−)not only accelerate the ring-opening polymerization of tetrahydrofuran,but also promote the formation of highly ion-conductive and sustainable interphases on Li metal anodes without sacrificing the Li^(+)conductivity of electrolytes,which is favorable for Li^(+)transport kinetics at low *** of this polymer electrolyte in Li||LifePO_(4)cells show 82.3%capacity retention over 1000 cycles at 30℃and endow stable discharge capacity at−30℃.Remarkably,the Li||LifePO4 cells retain 52%of their room-temperature capacity at−20℃and 0.1 *** rational design of dual-salt polymer-based electrolytes may provide a new perspective for the stable operation of quasi-solid-state batteries at low temperatures.

关键词： Poly(tetrahydrofuran) Dual-salt electrolyte Solidel ectrolyte interphase Low-temperature operation Quasi-solid-state battery

Three-dimensional numerical analysis of plant-soil hydraulic interactions on pore water pressure of vegetated slope under different rainfall patterns

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3696-3706页

作者： Haowen guo Charles Wang Wai ng Qi Zhang Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina

Understanding the pore water pressure distribution in unsaturated soil is crucial in predicting shallow landslides triggered by rainfall,mainly when dealing with different temporal patterns of rainfall ***,the hydrological response of vegetated slopes,especially three-dimensional(3D)slopes covered with shrubs,under different rainfall patterns remains unclear and requires further *** address this issue,this study adopts a novel 3D numerical model for simulating hydraulic interactions between the root system of the shrub and the surrounding *** series of numerical parametric studies are conducted to investigate the influences of slope inclination,rainfall pattern and rainfall *** rainfall patterns(advanced,bimodal,delayed,and uniform)and two rainfall durations(4-h intense and 168-h mild rainfall)are considered to study the hydrological response of the *** computed results show that 17%higher transpiration-induced suction is found for a steeper slope,which remains even after a short,intense rainfall with a 100-year return *** extreme rainfalls with advanced(PA),bimodal(PB)and uniform(PU)rainfall patterns need to be considered for the short rainfall duration(4 h),while the delayed(PD)and uniform(PU)rainfall patterns are highly recommended for long rainfall durations(168 h).The presence of plants can improve slope stability markedly under extreme rainfall with a short duration(4 h).for the long duration(168 h),the benefit of the plant in preserving pore-water pressure(PWP)and slope stability may not be sufficient.

关键词： Root-soil interactions Rainfall patterns Slope stability Three-dimensional(3D)

Weighted Composition Operators That Preserve frames On Weighted Hardy Spaces

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Acta Mathematica Sinica,English Series 2024年第7期40卷 1645-1654页

作者： Ya Li Dong rui Liu guo Xiang Lu School of Mathematical Sciences and LPMC Nankai UniversityTianjin300071P.R.China School of Statistics and Mathematics Zhongnan University of Economics and LawWuhan430073P.R.China

In this paper, we characterize weighted composition operators that preserve frames on the weighted Hardy spaces in the unit disk. In particular, we obtain the symbol properties of the bounded invertible weighted composition operators. Moreover, we establish the equivalence between bounded invertible operators and frame-preserving operators. furthermore, we show that weighted composition operator preserves frames if and only if it preserves the Riesz bases property. Additionally,we investigate the weighted composition operators that preserve tight or normalized tight frames on the Dirichlet space.

关键词： Weighted composition operators Weighted Hardy spaces frames invertible

Accelerating the solving of mechanical equilibrium caused by lattice misfit through deep learning method

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Advances in Manufacturing 2024年第3期12卷 512-521页

作者： Chen-Xi guo Hui-Ying Yang rui-Jie Zhang Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing100083People’s Republic of China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing100083People’s Republic of China

Precipitation is a common phenomenon that occurs during heat *** is internal stress around the precipitate owing to the lattice misfit between the precipitate and *** internal stress has a significant influence not only on the precipitation kinetics but also on the material *** misfit stress can be obtained by numerically solving the mechanical equilibrium ***,this process is complex and *** developed a new approach based on deep learning to accelerate the solution *** training data were first generated by a phase-field model coupled with elastic mechanical equilibrium equations,which were solved using the finite difference *** obtained precipitate morphologies and corresponding stress distributions were input data for training the physics-informed(PI)UNet *** well-trained PI-UNet model can then be applied to predicting stress distributions with the precipitate morphology as the *** accuracy and efficiency are discussed in this *** results showed that the PI-UNet model was an appropriate approach for quickly predicting the misfit stress between the precipitate and matrix.

关键词： Precipitate Mechanical equilibrium Heat treatment Deep learning

A new monitoring index for ecological vulnerability and its application in the Yellow River Basin,China from 2000 to 2022

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Journal of Arid Land 2024年第9期16卷 1163-1182页

作者： guo Bing XU Mei ZHAng rui LUO Wei School of Civil Engineering and Geomatics Shandong University of TechnologyZibo 255000China Key Laboratory of Remote Sensing of Gansu Province Heihe Remote Sensing Experimental Research StationNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China North China Institute of Aerospace Engineering Langfang 065000China

The ecological environment of the Yellow River Basin has become more fragile under the combined action of natural and manmade ***,the change mechanisms of ecological vulnerability in different sub-regions and periods vary,and the reasons for this variability are yet to be ***,in this study,we proposed a new remote sensing ecological vulnerability index by considering moisture,heat,greenness,dryness,land degradation,and social economy indicators and then analyzed and disclosed the spatial and temporal change patterns of ecological vulnerability of the Yellow River Basin,China from 2000 to 2022 and its driving *** results showed that the newly proposed remote sensing ecological vulnerability index had a high accuracy,at 86.36%,which indicated a higher applicability in the Yellow River *** 2000 to 2022,the average remote sensing ecological vulnerability index of the Yellow River Basin was 1.03,denoting moderate vulnerability *** intensive vulnerability area was the most widely distributed,which was mostly located in the northern part of Shaanxi Province and the eastern part of Shanxi *** 2000 to 2022,the ecological vulnerability in the Yellow showed an overall stable trend,while that of the central and eastern regions showed an obvious trend of *** gravity center of ecological vulnerability migrated southwest,indicating that the aggravation of ecological vulnerability in the southwestern regions was more severe than in the northeastern regions of the *** dominant single factor of changes in ecological vulnerability shifted from normalized difference vegetation index(NDVI)to temperature from 2000 to 2022,and the interaction factors shifted from temperature∩NDVI to temperature∩precipitation,which indicated that the global climate change exerted a more significant impact on regional *** above results could provide decision support for the ecological protection and restoration of the Y

关键词： ecological vulnerability spatio-temporal pattern gravity center migration trajectory interaction factors geodetector green index q-value

Sawtooth-enhanced bend sensor for gesture recognition

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Science China(Technological Sciences) 2024年第6期67卷 1727-1736页

作者： BAI YanRu ZHAng ZiHang WAng HaoYu guo rui LI XiSheng School of Automation and Electrical Engineering University of Science and Technology BeijingBeijing100083China School of Advanced Engineering University of Science and Technology BeijingBeijing100083China School of Precision Instrument and Opto-Electronics Engineering Tianjin UniversityTianjin300072China School of Computer and Communication Engineering University of Science and Technology BeijingBeijing100083China

Gesture recognition has diverse application prospects in the field of human-computer ***,gesture recognition devices based on strain sensors have achieved remarkable results,among which liquid metal materials have considerable advantages due to their high tensile strength and *** improve the detection sensitivity of liquid metal strain sensors,a sawtooth-enhanced bending sensor is proposed in this *** with the results from previous studies,the bending sensor shows enhanced resistance *** addition,combined with machine learning algorithms,a gesture recognition glove based on the sawtooth-enhanced bending sensor is also fabricated in this study,and various gestures are accurately *** the fields of human-computer interaction,wearable sensing,and medical health,the sawtooth-enhanced bending sensor shows great potential and can have wide application prospects.

关键词： liquid metal bending sensor gesture recognition machine learning

Maximum Power Point Tracking Technology for PV Systems: Current Status and Perspectives

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Energy Engineering 2024年第8期121卷 2009-2022页

作者： Bo Yang rui Xie Zhengxun guo faculty of Electric Power Engineering Kunming University of Science and TechnologyKunming650500China Intelligent Electric Power Grid Key Laboratory of Sichuan Province Chengdu610065China foshan Graduate School of Innovation Northeastern UniversityFoshan528311China College of Information Science and Engineering Northeastern UniversityShenyang110819China

Maximum power point tracking(MPPT)technology plays a key role in improving the energy conversion efficiency of photovoltaic(PV)systems,especially when multiple local maximum power points(LMPPs)occur under partial shading conditions(PSC).It is necessary to modify the operating point efficiently and accurately with the help of MPPT technology to maximize the collected *** though a lot of research has been carried out and impressive progress achieved for MPPT technology,it still faces some challenges and ***,the mathematical model established for PV cells is not precise ***,the existing algorithms are often optimized for specific conditions and lack comprehensive adaptability to the actual operating ***,a single algorithm may not be able to give full play to its *** the end,the selection criteria for choosing the suitable MPPT algorithm/converter combination to achieve better performance in a given scenario is very ***,this paper systematically discusses the current research status and challenges faced by PV MPPT technology around the three aspects of MPPT models,algorithms,and hardware *** in-depth thinking and discussion,it also puts forward positive perspectives on future development,and five forward-looking solutions to improve the performance of PV systems MPPT are suggested.

关键词： PV systems MPPT partial shading condition DC-DC converter

Reduction behavior of iron ore powder by high-volatile coal in thermogravimetric-gas chromatographic and kinetic analysis

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Journal of Iron and Steel Research International 2024年第1期31卷 92-107页

作者： rui-meng Shi Qi-yuan Mi Bin Li Xiao Shi Chong Zou Jing guo Han-jie guo School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an710055ShaanxiChina China International Engineering Consulting Corporation Beijing100048China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing100083China

The reduction behavior of iron ore powder by high-volatile coal was investigated,and its kinetic mechanism was *** effect of volatiles in coal on the reduction reaction of iron ore was compared by utilizing a Xinjiang lignite with a high volatile content and its pyrolysis carbon produced by high-temperature pyrolysis to remove volatiles,serving as a *** mass loss and gas composition of the samples during the reduction process were detected using thermo-gravimetric analysis and gas chromatography,and the morphological changes of iron ore powder were observed through scanning electron *** kinetic parameters of the iron oxide reduction reaction were calculated by the flynn-Ozawa-Wall method,and the kinetic mechanism of volatile participation in the iron oxide reduction reaction was determined through the Coats-Redfern *** results indicate that the coupling effect between the high-volatile coal pyrolysis and reduction reactions occurs during the second stage of the entire coupling process,which corresponds to the late stage of coal pyrolysis with a substantial release of H_(2)and *** volatiles in coal actively participated in the reduction reaction,reducing the initiation temperature of the reaction by around 200℃.The reduction of iron oxides by high-volatile coal was jointly promoted by the"hydrogen cycle"and"carbon cycle",resulting in a higher reduction extent and metallization rate at the end of the *** high-volatile coal was used as the reductant,the average activation energy for the entire process was 76.5 kJ/mol,a significant decrease compared to the employment of pyrolysis carbon without volatiles as the reductant(1167 kJ/mol).

关键词： Direct reduction High-volatile coal Volatile Kinetics Reduction mechanism