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Evaluating transient behaviour of large-scale photovoltaic systems during lightning events using enhanced finite difference time domain method with variable cell size approach

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HIGH VOLTAGE 2024年第3期9卷 636-647页

作者： Hetita, Ibrahim Mansour, Diaa-Eldin A. Han, Yang Yang, Ping wang, Congling Darwish, Mohamed M. F. Lehtonen, Matti Zalhaf, Amr S. univ Elect sci & Technol china UESTC Sch Mech & Elect Engn Chengdu Peoples R China Helwan univ Fac Engn Elect Power & Machines Engn Dept Cairo Egypt Tanta univ Fac Engn Elect Power & Machines Engn Dept Tanta Egypt Egypt Japan univ sci & Technol Fac Engn Dept Elect Power Engn Alexandria Egypt Benha univ Fac Engn Shoubra Dept Elect Engn Cairo Egypt Aalto univ Sch Elect Engn Dept Elect Engn & Automation Espoo Finland GMC Dept Med Srinagar Jammu And Kashm India

Photovoltaic (PV) arrays are usually installed in open areas; hence, they are vulnerable to lightning strikes that can result in cell degradation, complete damage, service disruption, and increased maintenance costs. As a result, it is imperative to develop an effective and efficient lightning protection system by evaluating the transient behaviour of PV arrays during lightning events. The aim is to evaluate the transient analysis of large-scale PV systems when subjected to lightning strikes using the finite difference time domain (FDTD) technique. Transient overvoltages are calculated at various points within the mounting system. To optimise the FDTD method's execution time and make it more suitable for less powerful hardware, a variable cell size approach is employed. Specifically, larger cell dimensions are used in the earthing system and smaller cell dimensions are used in the mounting system. The FDTD method is utilised to calculate the temporal variation of transient overvoltages for large-scale PV systems under different scenarios, including variations in the striking point, soil resistivity, and the presence of a metal frame. Simulation results indicate that the highest transient overvoltages occur at the striking point, and these values increase with the presence of a PV metal frame as well as with higher soil resistivity. Furthermore, a comparison is performed between the overvoltage results obtained from the FDTD approach and the partial element equivalent circuit (PEEC) method at the four corner points of the mounting systems to demonstrate the superior accuracy of the FDTD method. Besides, a laboratory experiment is conducted on a small-scale PV system to validate the simulation results. The calculated overvoltages obtained from the FDTD and PEEC methods are compared with the measured values, yielding a mean absolute error of 5% and 11% for the FDTD and PEEC methods, respectively, thereby confirming the accuracy of the FDTD simulation model.

关键词： FDTD METHOD MODEL

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Common-path illumination in ESPI: enhancing sensitivity for measuring specular deformation

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CHINESE OPTICS LETTERS 2024年第8期22卷 081201-081201页

作者： Yan, Peizheng Liu, Xiangwei Zhou, Xinda Ba, Rongsheng Zhou, Hanxuan wang, Yonghong Li, Jie Hefei univ Technol Sch Instrument Sci & Optoelect Engn Hefei 230009 Peoples R China Hefei univ Technol Anhui Prov Key Lab Measuring Theory & Precis Instr Hefei 230009 Peoples R China china Acad Engn Phys Laser Fus Res Ctr Mianyang 621900 Peoples R China

In this study, an innovative technique is introduced to significantly enhance the sensitivity of electronic speckle pattern interferometry (ESPI) for the dynamic assessment of specular (mirrorlike) object deformations. By utilizing a common-path illumination strategy, wherein illumination and observation beams are precisely aligned, this method effectively doubles the optical path difference, leading to a twofold increase in measurement sensitivity. In addition, this method mitigates the effects of speckle noise on the measurement of minor deformations, expanding the applications of ESPI. Theoretical and experimental evaluations corroborate the efficacy of this approach.

关键词： ESPI common-path illumination measurement sensitivity specular deformation SPECKLE-PATTERN INTERFEROMETRY SHEAROGRAPHY DSPI

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Multiscale interaction analysis of Landfall Typhoon Lekima (2019) based on vorticity equation diagnosis

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TROPICAL CYCLONE RESEARCH AND REVIEw 2024年第2期13卷 136-146页

作者： Xue, wenbo Yu, Hui Tang, Shengming Chinese Acad Meteorol sci Beijing Peoples R China univ Chinese Acad sci Beijing Peoples R China Shanghai Typhoon Inst china Meteorol Adm Shanghai Peoples R China

To investigate the multiscale interaction characteristics of Landfall Typhoon Lekima (2019), this study analyzed the characteristics of the different scale vortex structure and interactions among different scales based on vorticity equation diagnosis. The analysis is based on the simulation results of the wRF model which has been thoroughly verified. The main results are as follows: the original vorticity dominated by the meso-alpha scale vorticity increases with height and then decreases, with maximum vorticity distributed at 900 hPa. The meso-beta scale vorticity varies significantly with altitude, while the meso-gamma scale vorticity field exhibits obvious positive vorticity below 850 hPa. The meso-alpha scale vorticity tendency primarily maintains negative, contributing significantly to the overall reduction in the original vorticity field over time. The increase in mid-to-upper-level (above 550 hPa) original vorticity is mainly related to the variations in the meso-beta and meso-gamma scale vorticity fields. The original vorticity dominated by the meso-alpha scale vorticity increases with height and then decreases, and the whole layer vorticity decreases over time. The meso-beta scale vorticity varies significantly with altitude and time, while the meso-gamma scale vorticity field consistently exhibits significant positive vorticity below 850 hPa. The vorticity equation diagnosis revealed that the primary source terms of the vorticity tendencies are the twisting and stretching terms, and the main sink terms being horizontal and vertical vorticity transport terms below 900 hPa. The source terms and sink terms exchange above 850 hPa. Scale separation results show that the primary contributions of all impact factors originate from the meso-alpha and meso-gamma scale fields (accounting for over 80% of the total), with the contribution of the meso-alpha scale being less than that of the meso-gamma scale and a notable contribution over 35.5% of the interactions betwe

关键词： Tropical cyclone Multiscale interaction Vorticity equation diagnosis TROPICAL CYCLONES TOPOGRAPHY

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well-controlled Organocatalytic Ring-opening Polymerization of Seven-membered Cyclic Carbonates with Cyclohexyl Fusion

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CHEMICAL RESEARCH IN CHINESE univERSITIES 2024年第5期40卷 856-862页

作者： Zhang, wei Shan, Si-Yi Dai, Jiang Cai, Zhongzheng Zhu, Jian-Bo Tianjin univ sci & Technol Coll Chem Engn & Mat Sci Tianjin Key Lab Brine Chem Engn & Resource Ecoutil Tianjin 300457 Peoples R China Sichuan univ Coll Chem Natl Engn Lab Ecofriendly Polymer Mat Sichuan Chengdu 610064 Peoples R China

Developing green and well-controlled polymerization methods is of great significance for the preparation of biomedical polymer materials. In this contribution, an efficient organocatalytic ring-opening polymerization (ROP) of a class of seven-membered cyclic carbonates (T6DO, T6HDO, C6DO, C6HDO) containing cis- or trans-cyclohexane structure was established. Organic catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) promoted living polymerization of these cyclic carbonates to deliver polycarbonate and block copolymer products with predictable molecular weights and narrow dispersity. The robust TBD-mediated ROP at 90 degrees C showcased turnover frequency (TOF) up to 10(3) h(-1). The resulting amorphous polycarbonates displayed good thermal stability.

关键词： CO2 Organic catalyst Living ring-opening polymerization Aliphatic polycarbonate KINETIC RESOLUTION POLYMERIZATION RAC-LACTIDE

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A non-antibiotic organic coating on ZA6-1 surface releasing different concentrations of sodium dodecyl sulphate/levulinic acid for orthopaedic application

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BIOSURFACE AND BIOTRIBOLOGY 2024年第2期10卷 42-51页

作者： Zou, Feng Zhao, Deren Liu, Yangkai Lu, Qiqi Liu, Hulin Chen, Zilin Fang, Yaxing Tan, Xiaodong Xiang, Yunjie Feng, Xue Zhang, Yongping Rao, Xi Southwest univ Sch Mat & Energy Chongqing Peoples R China Southwest univ Chongqing Key Lab Soft Matter Mat Chem & Funct Mfg Chongqing Peoples R China Chongqing med univ Univ Town Hosp Dept Clin Lab Chongqing Peoples R China

Bone implantation surgery is often accompanied by bacterial infection, resulting in infectious bone non-union, pathological fracture and other serious consequences, which will aggravate the pain of patients. A non-antibiotic coating consisting of sodium dodecyl sulphate (SDS) and levulinic acid (LA) with different concentrations was prepared by the authors on the zinc-aluminium alloy (ZA6-1) using a wet chemistry treatment for orthopaedic application. The influence of SDS/LA concentrations on the surface morphology, composition and performance of the developed coating was investigated. The results showed that as-prepared coating on a zinc alloy surface could improve the substrate's corrosion resistance and increase the degradation rate from 0.82 to 19.70 mu m/year upon raising the SDS/LA concentration. Furthermore, higher hydrophilicity (100%) and morphology, as well as good cell adhesion and differentiation (ALP >95% for 7 days) were observed on coated zinc alloys. The increased SDS/LA concentration slightly weakens the biocompatibility and enhances the antibacterial performance of coated zinc alloys due to the synergistic effect of SDS/LA. Overall, the coating comprising 6 wt.% SDS and 9 wt.% LA showed excellent antibacterial action with a high level of biocompatibility, confirming its potential application for orthopaedic implants.

关键词： antibacterial biocompatibility biomaterials material property IN-VITRO ALLOY ANTIBACTERIAL ZINC BEHAVIOR CELLS BIODEGRADATION SANITIZER NANOTUBES MECHANISM

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Effect of electron beam irradiation on surface molecule and flashover voltage of epoxy composites

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HIGH VOLTAGE 2024年第3期9卷 528-536页

作者： Li, Mingru Niu, Huan Shang, Kai Lang, Jianyu Gao, Yafang Li, Bingnan Zhao, Jiuhui Li, Zhen Feng, Yang Li, Shengtao Xi An Jiao Tong univ State Key Lab Elect Insulat & Power Equipment Xian Shaanxi Peoples R China Harbin univ sci & Technol Key Lab Engn Dielect & Its Applicat Minist Educ Harbin Heilongjiang Peoples R China

The unsatisfactory insulating properties of solid-gas interfaces seriously restrict the development of high-voltage electrical equipment and threaten their power supply stability. Electron-beam irradiation (EBI) can effectively improve the surface flashover voltage of dielectrics. However, the underlying mechanism of EBI in tailoring the surface trap and improving the flashover voltage remains unclear. In this study, the surface morphologies and chemical compositions of epoxy composites treated with EBI were investigated. In addition, the surface wetting properties, surface charge migration parameters, and surface flashover voltages were experimentally characterised. It was found that EBI aggravated the surface morphology, changed the surface chemical components, and repressed surface charge transportation. As a result, the contact angle was reduced from 103.7 degrees to 78.43 degrees, and the flashover voltage in SF6 was increased from 35.26 to 38.90 kV. DFT calculations showed that the newly generated C-O-H and C=O bonds on the surface molecules after EBI formed charge centres at the molecular electrostatic potential, which enhanced the trapping effect of the surface deep trap. As a result, surface charge migration was repressed, and the surface flashover voltage was improved. This study could promote the further development of EBI on materials modification.

关键词： PERFORMANCE INSULATORS BREAKDOwN VACUUM

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Study on thermal cycling ageing resistance of performances of polypropylene/elastomer/boron nitride nanocomposites for high voltage direct current cable insulation

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HIGH VOLTAGE 2024年第3期9卷 556-565页

作者： Li, Jing Gao, Yu Song, Zheng Liu, Baixin Guo, Chenyi Chen, Yu Gao, Junguo Du, Boxue Tianjin univ Sch Elect & Informat Engn Tianjin Peoples R China State Grid Tianjin Chengxi Elect Power Supply Bran Tianjin Peoples R China Xi An Jiao Tong univ State Key Lab Elect Insulat & Power Equipment Xian Peoples R China Harbin univ sci & Technol Key Lab Engn Dielect & Its Applicat Minist Educ Harbin Peoples R China

The influences of thermal cycling ageing on structures and insulation performances of polypropylene (PP)/elastomer/boron nitride (BN) nanocomposites are investigated. The Melt blending method was used to prepare the nanocomposites, in which propylene-based elastomer (PBE) or ethylene-octene copolymer elastomer (EOC) was contained for comparison. Then, the samples were treated using a thermal cycling process with a temperature range from -30 to 150 degrees C, and the number of thermal cycles was set from 0 to 15. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry and X-ray diffraction measurements were taken to facilitate the comprehension of structural changes. Additionally, measurements were taken to assess the trap distribution and direct current (DC) breakdown strength of the samples. The obtained results revealed that following thermal cycling ageing, the morphology and crystallinity of PP/PBE/BN remained almost unchanged. In contrast, PP/EOC/BN exhibited substantial microstructural damage accompanied by a significant reduction in crystallinity. As the number of thermal cycles increased, the trap level and DC breakdown strength of PP/PBE/BN were maintained at high levels, while those of PP/EOC/BN initially remained stable but then experienced a sharp decline. It is suggested that the addition of BN nanoparticles enhances the thermal cycling ageing resistance of the PP/PBE blend, whereas it weakens this resistance of the PP/EOC blend.

关键词： POLYPROPYLENE IRRADIATION BEHAVIOR DEGRADATION

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Trade-offs between chemical resistance to herbivory and responses to abiotic stresses in invasive plants

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JOURNAL OF PLANT ECOLOGY 2024年第2期17卷 18-23页

作者： Zhou, Lifeng Yin, wandong Ding, Jianqing Henan univ Sch Life Sci State Key Lab Crop Stress Adaptat & Improvement Kaifeng 475004 Peoples R China

INTRODUCTION Plants change their traits to respond to shifting environments,enabling them to defend against biotic stresses such as herbivorous insects,and/or tolerate abiotic stresses,such as extreme climate(Callaway et al.2022;Zhang et al.2018,2022).There are often costs when plants produce secondary chemicals to adapt to varying biotic or abiotic environments(Abdala-Roberts et al.2016).

关键词： ENEMY RELEASE DEFENSE GROwTH DROUGHT GENERALIST SPECIALIST FLAVONOIDS ALLOCATION EVOLUTION RAGwEED

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Low Temperature Tetragonal Tungsten Bronze Oxides for Li-ion Storage

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CHEMICAL RESEARCH IN CHINESE univERSITIES 2024年第5期40卷 922-926页

作者： Xu, Chengxin Zhang, wenda Lou, Chenjie Li, Chengyu Xu, Ligang Shi, Yongchao Liu, Jie Luo, Huajie Fu, Jipeng Kuang, Xiaojun Tang, Mingxue Guilin univ Technol Coll Chem & Bioengn Guangxi Key Lab Electrochem & Magnetochem Funct Ma Guilin 541006 Peoples R China Ctr High Pressure sci & Technol Adv Res Beijing 100193 Peoples R China Guilin univ Technol Key Lab New Proc Technol Nonferrous Met & Mat Guangxi Key Lab Opt & Elect Mat & Devices Coll Mat Sci & EngnMinist Educ Guilin 541004 Peoples R China univ sci & Technol Beijing Sch Mat Sci & Engn Minist Educ Beijing 100083 Peoples R China univ sci & Technol Beijing Key Lab Adv Mat & Devices Postmoore Chips Minist Educ Beijing 100083 Peoples R China china Jiliang univ Inst Optoelect Mat & Devices Key Lab Rare Earth Optoelect Mat & Devices Zhejian Hangzhou 310018 Peoples R China

Nb-based tungsten bronze oxides have emerged as attractive materials in various fields, owing to the structural openings and simple synthesis method. In this work, the tetragonal tungsten bronze (TTB) NawNbO6 was prepared by solid state reaction at a relatively low temperature of 775 degrees C. The local structure was systematically studied by solid state nuclear magnetic resonance (SSNMR) with the aid of transition electronic microscopy (TEM). The analysis indicates that NawNbO6 has pentagonal, square, and triangular tunnels. Notably, square tunnels were partly occupied (50%) by Na, which creates the ability for the Li-ion storage with a volumetric capacity of 210 AhL-1 at 0.2 C. The 2D Na-23-Na-23 EXSY results further suggest the ability of ions to fast exchange between the tetragonal and pentagonal tunnels, resulting in a high-rate performance 20 C.

关键词： Tetragonal tungsten bronze Solid-state Na-23 NMR Nb-93 NMR spectrum Fast ion exchange

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Mechanism of plant-soil feedback in a degraded alpine grassland on the Tibetan Plateau

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JOURNAL OF PLANT ECOLOGY 2024年第2期17卷 188-199页

作者： Zhou, Tiancai Sun, Jian Shi, Peili Chinese Acad sci Inst Geog Sci & Nat Resources Res Key Lab Ecosyst Network Observat & Modelling Beijing 100101 Peoples R China Chinese Acad sci Inst Tibetan Plateau Res State Key Lab Tibetan Plateau Earth Syst Resources Beijing 100101 Peoples R China Minist Educ Key Lab Biodivers & Environm Qinghai Tibet Plateau Lhasa 850011 Peoples R China Tibet Res Acad Ecoenvironm sci Lhasa 850000 Peoples R China univ Chinese Acad sci Coll Resources & Environm Beijing 100049 Peoples R China

Although biotic and abiotic factors have been confirmed to be critical factors that affect community dynamics, their interactive effects have yet to be fully considered in grassland degradation. Herein, we tested how soil nutrients and microbes regulated plant-soil feedback (PSF) in a degraded alpine grassland. Our results indicated that soil total carbon (STC; from 17.66 to 12.55 g/kg) and total nitrogen (STN; from 3.16 to 2.74 g/kg) exhibited significant (P wth when the soil was sterilized, a high proportion of pathogens (36%) in ND non-sterilized soil resulted in a strong negative PSF on monocots. In contrast, the higher phenotypic plasticity of dicots coupled with a higher abundance of mutualists and saprophytes (70%) strongly promoted their survival and growth in SD with infertile soil. Our findings identified a novel mechanism that there was a functional group shift from monocots with higher vulnerability to soil pathogens in the ND fertile soil to dicots with higher dependence on nutritional mutualists in the degraded infertile soil. The emerging irreversible eco-evolutionary in PSF after degradation might cause a predicament for the restoration of degraded grassland.

关键词： plant-soil feedback plant function groups degradation alpine grassland Tibetan Plateau LITTER DECOMPOSITION COMMUNITY TRAITS DIVERSITY COMPETITION DEPENDENCE ECOSYSTEM DYNAMICS DRIVERS CARBON

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