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Effects of patchy distributed Artemisia capillaris on overland flow hydrodynamic characteristics

International Soil and Water Conservation Research 2019年第1期7卷 81-88页

作者： guanhua zhang Jiajun Hu Soil and Water Conservation Department Changjiang River Scientific Research InstituteChina Research Center on Mountain Torrent&Geologic Disaster Prevention of Ministry of Water Resources China Changjiang Water Resources Commission of the Ministry of Water Resources Wuhan 430010China

Laboratory-simulated rainfall experiments were conducted to quantify the effects of patchy distributed Artemisia capillaris on overland flow *** intensities of 60,90,120,and 150 mm h-1 were applied on a bare plot (CK) and four different patched patterns:a checkerboard pattern (CP),a banded pattern perpendicular to slope direction (BP),a single long strip parallel to slope direction (LP),and a pattern with small patches distributed like the letter'X'(XP).Each patterned plot underwent two sets of experiments,intact plant and root (the above-ground parts were removed),*** showed that flow velocity increased with rainfall intensity,and the lower slope velocity was higher than the upper *** removal of grass shoots significantly increased flow *** contributions of grass shoots and roots to the reductions in flow velocity under different rainfall intensities were *** shoots made greater contribution of 53-97% at 60 and 90 mm h-1,and the roots contributed more (51-81%) at 120 and 150 mm *** flow depth increased with rainfall intensity and it declined after the aboveground parts were *** numbers (Re) in this study were 25-80,indicating a laminar flow in the *** numbers (Fr) were ≥ 1 for CK and < 1 for patterned *** of the lower slope was higher than the upper ***-weisbach (f) and Manning (n) friction coefficient ranked in the order of CK < LP < BP/CP/XP with values of grass sections being higher than the bare sections and upper slope higher than the lower slope,and both decreased after removing the grass ***,CP,and XP performed more effectively than LP in retarding flow velocity and increasing hydraulic roughness.

关键词： Overland flow Vegetation pattern Hydrodynamics Soil erosion rate Simulated rainfall

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Probability-based analytical model for predicting the post-earthquake residual deformation of SDOF systems

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Earthquake Engineering and Engineering Vibration 2022年第2期21卷 341-358页

作者： zhang Qin Gong Susu Gong Jinxin zhang guanhua Xi Guangheng College of Civil and Transportation Engineering Hohai UniversityNanjing 210098China Highway Maintenance Technology Research and Development Center of Liaoning Provincial Communication Planning&Design Insitute Co.Ltd. Shenyang 110111China Department of Civil Engineering Dalian University of TechnologyDalian 116014China

A probability-based analytical model for predicting the seismic residual deformation of bilinear single-degreeof-freedom(SDOF)systems with a kinematic/Takeda hysteretic model is proposed based on a statistical analysis of the nonlinear time history response,and the proposed model explicitly incorporates the influence of record-to-record *** addition,the influence of primary parameters such as the natural vibration period,relative yield force coefficient,stiffness ratio and peak ground acceleration(PGA)on the seismic residual/maximum deformation ratio(dR/dm)are *** results show that significant dispersion of the dR/dm ratio is observed for SDOF systems under different seismic ground motion records,and the dispersion degree is influenced by the model parameters and record-to-record *** statistical distribution of the dR/dm results of SDOF systems can be described by a lognormal ***,a case study for seismic residual deformation and reparability assessment of the bridge structure designed with a single pier is carried out to illustrate the detailed analytical procedure of the probability-based analytical model proposed in this study.

关键词： residual deformation probability model repairability assessment single-degree-of-freedom system nonlinear seismic response record-to-record variability

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Numerical and experimental research of the characteristics of concentration solar cells

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Frontiers in Energy 2021年第2期15卷 279-291页

作者： Zilong WANG Hua zhang Binlin DOU Weidong WU guanhua zhang Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai 200093China

The development of automatic tracking solar concentrator photovoltaic systems is currently attracting growing *** concentration photovoltaic systems(HCPVs)combining triple-junction InGaP/lnGaAs/Ge solar cells with a concentrator provide high conversion *** mathematical model for triple-junction solar cells,having a higher efficiency and superior temperature characteristics,was established based on the one-diode equivalent circuit cell model.A paraboloidal concentrator with a secondary optic system and a concentration ratio in the range of 100X–150X along with a sun tracking system was developed in this *** GaInP/GalnAs/Ge triple-junction solar cell,produced by AZUR SPACE Solar Power,was also used in this *** solar cells produced by Shanghai Solar Youth Energy(SY)and Shenzhen Yinshengsheng Technology ***.(YXS)were used as comparison samples in a further comparative study at different concentration ratios(200X–1000X).A detailed analysis on the factors that influence the electrical output characteristics of the InGaP/lnGaAs/Ge solar cell was conducted with a dish-style concentrating photovoltaic *** results show that the short-circuit current(Isc)and the open-circuit voltage(Voc)of multi-junction solar cells increases with the increasing concentration ratio,while the cell efficiency(ηc)of the solar cells increases first and then decreases with increasing concentration *** increasing solar cell temperature,Isc increases,while Voc andηc decrease.A comparison of the experimental and simulation results indicate that the maximum root mean square error is less than 10%,which provides a certain theoretical basis for the study of the characteristics of triple-junction solar cell that can be applied in the analysis and discussion regarding the influence of the relevant parameters on the performance of high concentration photovoltaic systems.

关键词： concentration three-junction solar cell mathematical model electrical properties solar energy

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Influence of vegetation parameters on runoff and sediment characteristics in patterned Artemisia capillaris plots

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Journal of Arid Land 2014年第3期6卷 352-360页

作者： guanhua zhang GuoBin LIU PingCang zhang Liang YI Department of Soil and Water Conservation Changjiang River Scientific Research Institute State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Institute of Soil and Water Conservation Northwest A&F University Hubei Academy of Environmental Sciences

Vegetation patterns are important in the regulation of earth surface hydrological processes in arid and semi-arid areas. Laboratory-simulated rainfall experiments were used at the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Yangling, northwestern China, to quantify the effects of Artemisia capillaris patterns on runoff and soil loss. The quantitative relationships between runoff/sediment yield and vegetation parameters were also thoroughly analyzed using the path analysis method for identifying the reduction mechanism of vegetation on soil erosion. A simulated rainfall intensity of 90 mm/h was applied on a control plot without vegetation （Co） and on the other three different vegetation distribution patterns： a checkerboard pattern （CP）, a banded pattern perpendicular to the slope direction （BP）, and a single long strip parallel to the slope direction （LP）. Each patterned plot received two sets of experiments, i.e. intact plants and roots only, respectively. All treatments had three replicates. The results showed that all the three other different patterns （CP, BP and LP） of A. capillaris could effectively reduce the runoff and sediment yield. Compared with Co, the other three intact plant plots had a 12%-25% less runoff and 58%-92% less sediment. Roots contributed more to sediment reduction （46%-70%）, whereas shoots contributed more to runoff reduction （57%-81%）. BP and CP exhibited preferable controlling effects on soil erosion compared with LP. Path analysis indicated that root length density and plant number were key parameters influencing runoff rate, while root surface area density and root weight density were central indicators affecting sediment rate. The results indicated that an appropriate increase of sowing density has practical significance in conserving soil and water.

关键词： arid and semi-arid areas Artemisia capillaris patches runoff and sediment roots and shoots vegetation parameters

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Osiers-sprout-like heteroatom-doped carbon nanofibers as ultrastable anodes for lithium/sodium ion storage

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Nano Research 2018年第7期11卷 3791-3801页

作者： Hang zhang guanhua zhang Zhiqin Li Ke Qu Huimin Shi Qingfeng zhang Huigao Duan Jianhui Jiang College of Chemistry and Chemical Engineering Hunan University Changsha 410082 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body National Engineering Research Center for High Efficiency Grinding College of Mechanical and Vehicle Engineering Hunan University Changsha 410082 China Department of Materials Science and Engineering Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA

We report an in situ carbothermic reduction process to prepare osiers-sprout-like heteroatom-doped carbon nanofibers. The dosage of copper salts and a unique annealing process have a crucial effect on the development of this unique carbon structure. A systematic analysis is performed to elucidate the possible mechanism of synthesis of the carbon nanofibers decorated with carbon bubbles. As anodes for rechargeable lithium/sodium ion batteries, the heteroatom-doped nanofibers exhibit high reversible capacities and satisfactory long-term cycling stabilities. The osiers-sprout-like heteroatom-doped carbon nanofiber electrodes deliver an ultrastable cycling performance with reversible capacities of 480 and 160 mAh·g^-1 for lithium-ion and sodium-ion batteries after 900 cycles at a current density of 800 mA·g^-1, respectively.

关键词： doped carbon nanofibers carbothermic reduction anodes lithium-ion batteries sodium-ion batteries

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Review of small aspheric glass lens molding technologies

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Frontiers of Mechanical Engineering 2017年第1期12卷 66-76页

作者： Shaohui YIN Hongpeng JIA guanhua zhang Fengjun CHEN Kejun ZHU National Engineering Research Center for High Efficiency Grinding Hunan University Changsha 410082 China School of Mechanical Engineering Xiangtan University Xiangtan411105 China

Aspheric lens can eliminate spherical aberra- tions, coma, astigmatism, field distortions, and other adverse factors. This type of lens can also reduce the loss of light energy and obtain high-quality images and optical characteristics. The demand for aspheric lens has increased in recent years because of its advantageous use in the electronics industry, particularly for compact, portable devices and high-performance products. As an advanced manufacturing technology, the glass lens molding process has been recognized as a low-cost and high-efficiency manufacturing technology for machining small-diameter aspheric lens for industrial production. However, the residual stress and profile deviation of the glass lens are greatly affected by various key technologies for glass lens molding, including glass and mold-die material forming, mold-die machining, and lens molding. These key technical factors, which affect the quality of the glass lens molding process, are systematically discussed and reviewed to solve the existing technical bottlenecks and problems, as well as to predict the potential applicability of glass lens molding in the future.

关键词： aspheric glass lens mold-die manufacturing,lens molding molding process simulation

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Highly active Fe_(7)S_(8) encapsulated in N-doped hollow carbon nanofibers for high-rate sodium-ion batteries

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Journal of Energy Chemistry 2021年第2期30卷 26-35,I0002页

作者： Chengzhi zhang Donghai Wei Fei Wang guanhua zhang Junfei Duan Fei Han Huigao Duan Jinshui Liu Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology College of Materials Science and EngineeringHunan UniversityChangsha 410082HunanChina State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082HunanChina School of Materials Science and Engineering Changsha University of Science and TechnologyChangsha 410004HunanChina

Nanostructured iron sulfides are regarded as a potential anode material for sodium-ion batteries in virtue of the rich natural abundance and remarkable theoretical ***,poor rate performance and inferior cycling stability caused by sluggish kinetics and volume swelling represent two main obstacles at present. The previous research mainly focuses on nanostructure design and/or hybridizing with conductive *** boosting the property by adjusting Fe/S atomic ratio in iron sulfides is rarely *** this work,Fe_7 S_8 and FeS_2 encapsulated in N-doped hollow carbon fibers(NHCFs/Fe_7 S_8 and NHCFs/FeS_2) are constructed by a combined chemical bath deposition and subsequent sulfidation *** well-designed NHCFs/Fe_(7) S_(8) electrode displays a remarkable capacity of 517 mAh g^(-1) at 2 A g^(-1)after 1000 cycles and a superb rate capability with a capability of 444 mAh g^(-1) even at 20 A g^(-1) in etherbased ***,the rate capability of NHCFs/Fe_(7) S_(8) is superior to that of the contrast NHCFs/FeS_(2) electrode and also much better than the values of the most previously reported iron sulfide-based *** in-depth mechanism explanation is explained by further experimental analysis and theoretical calculation,revealing Fe_(7) S_(8) displays improved intrinsic electronic conductivity and faster Na^(+) diffusion coefficient as well as higher reaction reversibility.

关键词： Sodium-ion batteries Anode High rate Iron sulfides N-doped hollow carbon fibers

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A comprehensive review of recent advancements and developments in heat exchanger network synthesis techniques

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Science China(Technological Sciences) 2024年第2期67卷 335-356页

作者： XU Yue LIU WeiWei zhang Lu CUI Guo Min XIAO Yuan zhang guanhua YANG QiGuo School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China

The rapid development of computational technology and the increasing energy demand have improved heat exchanger network(HEN)*** HEN synthesis involves several optimizations of matches,distributions of heat loads,and stream splitting of heat ***,obtaining good results at high efficiency has been the main standard for evaluating the techniques in the research area of HEN *** paper first summarizes and analyzes the main contributions of the existing HEN synthesis *** compare related data quantitively,information on ten typical cases is presented in this ***,recently improved solutions for commonly encountered existing literature cases demonstrate the evolution and competition trends in the field of HEN *** comparison data presented in this paper not only provide a useful reference for future research but also present the optimization *** on the findings of this study,it is noted that there is still a large room for improvement,and current approaches are incapable of dealing with all HEN ***,it is still difficult to escape a local optimum and overcome structural constraints when seeking the global *** a follow-up to the current work,the parallel computing mode and adaptively coordinating the ratio of global and local searching abilities are major development trends for future investigation.

关键词： heat integration heat exchanger network synthesis sequential synthesis method simultaneous synthesis method optimization techniques development optimization quality

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The regulation mechanism and heat transfer enhancement of composite mixed paraffin and copper foam phase change materials

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Science China(Technological Sciences) 2023年第8期66卷 2346-2360页

作者： YANG HanXue zhang guanhua DOU BinLin CUI GuoMin YAN XiaoYu LU Wei WANG ZiLong School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Environment and Sustainability Institute University of ExeterPenrynCornwall TR109FEUK

Phase change materials(PCMs)have remarkable energy storage capacity and promising applications in the field of thermal control of electronic *** problem of thermal property improvement and heat transfer of PCMs in metal-foam heatsinks is an important task for thermal management of electronic *** paraffin samples were prepared by mixing appropriate proportions of paraffin(mass)at various *** scanning calorimetry analysis revealed that the maximum enthalpy of 206.3 J/g is obtained by mixing 20%of 17°C liquid paraffin and 80%of 29℃ solid *** and cooling cycling tests revealed that mixed paraffin exhibits excellent thermal stability and that the regulation method marginally affects thermal ***,composites were prepared by embedding PCM into a copper foam by melt *** thermal conductivity of the composites increased to 4.35 W/(m K),corresponding to 20 times its original *** addition,density functional theory and experimental results were in good agreement,indicating that the regulation method is practical and effective.

关键词： phase change materials regulation mechanism temperature dependence thermal conductivity heat transfer enhancement

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Tailoring polysulfide trapping and kinetics by engineering hollow carbon bubble nanoreactors for high-energy Li-S pouch cells

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Nano Research 2021年第5期14卷 1355-1363页

作者： Lei Wang Shuangke Liu Jin Hu Xianan zhang Xin Li guanhua zhang Yujie Li Chunman Zheng Xiaobin Hong Huigao Duan National Engineering Research Center for High Efficiency Grinding College of Mechanical and Vehicle EngineeringHunan UniversityChangsha410082China College of Aerospace Science and Engineering National University of Defense TechnologyChangsha410073China School of Mechatronics Engineering and Automation Foshan UniversityFoshan528225China

Despite great progress of lithium-sulfur(Li-S)battery performance at the laboratory-level,both key parameters and challenges at cell scales to achieve practical high energy density require high-sulfur-loading cathodes and lean ***,a novel carbon foam integrated by hollow carbon bubble nanoreactors with ultrahigh pore volume of 6.9 cm3·g−1 is meticulously designed for ultrahigh sulfur content up to 96 wt.%.Tailoring polysulfide trapping and ion/electron transport kinetics during the charge-discharge process can be achieved by adjusting the wall thickness of hollow carbon *** a further in-depth understanding of electrochemical reaction mechanism for the cathode is impelled by the in-situ Raman *** a result,the as-prepared cathode delivers high specific capacitances of 1,269 and 695 mAh·g−1 at 0.1 and 5 C,***,Li-S pouch cells with high areal sulfur loading of 6.9 mg·cm−2 yield exceptional practical energy density of 382 Wh·kg−1 under lean electrolyte of 3.5µL·mg−1,which demonstrates the great potential for realistic high-energy Li-S batteries.

关键词： hollow carbon bubble nanoreactors ultrahigh pore volume tunable wall thickness high energy density lithium-sulfur batteries

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