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Hydrological and sediment connectivity under freeze-thaw meltwater compound erosion conditions on a loessal slope

International Soil and Water Conservation Research 2023年第2期11卷 402-411页

作者： Tian Wang Jingsi li Jingming Hou Yongyong Ma Peng li Yu Tong Jing li Zhanbin LI State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China Xi'an University of TechnologyXi'an710048ShaanxiChina Key Laboratory of National Forestry Administration on Ecological Hydrology and Disaster Prevention in Arid Regions Xian University of TechnologyXi'an 710048ShaanxiChina Shaanxi Province Institute of Water Resources and Electric Power Investigation and Design Xi'an710005ShaanxiChina

Freeze-thaw processes can influence hydrology,soil erosion,and morphological development by altering the connectivity between active pathways of water and sediment transport.Concentrated flow experi-ments were conducted involving frozen,shallow thawed,and unfrozen soil slopes under 1,2,and 4 L/min runoff rates at a temperature of approximately 5℃.In this study,hydrological connectivity was analysed via the simplified hydrological curve and relative surface connection function.Sediment con-nectivity was analysed via the sediment structure connectivity and sediment functional connectivity.Results indicated that hydrological connectivity was greatest on frozen slopes(FS),followed by shallow thawed slopes(STS),and unfrozen slopes(UFS)given a constant flow rate.Hydrological connectivity increased with increasing runoff rate for each freeze-thaw condition.Freezing condition and runoff rate exhibited a positive response to the hydrological connectivity.Sediment structure connectivity increased with increasing runoff rate for each slope condition.The ordering of sediment structure connectivity across freeze-thaw condition was that FS was greater than STS while STS was greater than UFS inde-pendent of flow rate.Sediment functional connectivity included longitudinal,lateral,and vertical con-nectivity components.Sediment longitudinal and vertical connectivity indicated a trend of first increasing and then decreasing under the different runoff rates and freeze-thaw conditions.For a given runoff rate,the ordering of sediment longitudinal and vertical connectivity across freeze-thaw condition was that FS was greater than STS while STS was greater than UFS.Sediment lateral connectivity exhibited a trend of first decreasing and then stabilizing.The ordering of sediment lateral connectivity across freeze-thaw condition was that UFS was greater than STS while STS was greater than FS.FS could more easily reach longitudinal and vertical penetration.Sediment longitudinal and vertical connectivity rates demonstrated increasing trends

关键词： Freeze-thaw Runoff Erosion Structureand functional connectivity Loessal slope

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Effects of a check dam system on the runoff generation and concentration processes of a catchment on the Loess Plateau

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International Soil and Water Conservation Research 2022年第1期10卷 86-98页

作者： Shuilong Yuan Zhanbin LI li Chen Peng li Zeyu Zhang Junzheng Zhang Anna Wang kunxia Yu State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China Xi'an University of TechnologyXi'an710048ShaanxiChina Key Laboratory of National Forestry Administration on Ecological Hydrology and Disaster Prevention in Arid Regions Xi'an University of TechnologyXi'an710048ShaanxiChina Desert Research Institute Las VegasNV89012USA Institute of Soil and Water Conservation Investigation and Planning of Shaanxi Province Xi'an710100ShaanxiChina

As an important soil and water conservation engineering measure,more than 100,000 check dams are constructed across the Loess Plateau;these dams play a vital role in reducing floods and sediment in the region.However,the effects of check dams on hydrologic process are still unclear,particularly when they are deployed as a system for watershed soil and water management.This study examined the watershed hydrologic process modulated by the check dam system in a typical Loess Plateau catchment.By simulating scenarios with various numbers of check dams using a distributed physically-based hydro-logical model,the effects of the number of check dams on runoff generation and concentration were analyzed for the study catchment.The results showed that the presence of check dams reduced the peak discharge and the flood volume and extended the flood duration;the reduction effect on peak discharge was most significant among the three factors.The system of check dams substantially decreased the runoff coefficient,and the runoff coefficient reduction rate was greater for rainstorms with shorter return periods than for rainstorms with longer return periods.The check dams increased the capacity of the catchment regulating and storing floods and extended the average runoff concentration time in the catchment that flattened the instantaneous unit hydrograph.This study reveals the influencing mech-anism of check dam system on the watershed hydrological process under heavy rainstorm conditions and provides a theoretical basis for evaluating the effects of numerous check dams on regional hydrology and water resources on the Loess Plateau.

关键词： Check dam system Runoff generation Runoff concentration Instantaneous unit hydrograph Loess Plateau

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Fluid-Thermal-Mechanical Coupled Analysis and Optimized Design of Printed Circuit Heat Exchanger with Airfoil Fins of S-CO_(2) Brayton Cycle

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Journal of Thermal Science 2022年第6期31卷 2264-2280页

作者： JIANG Tao li Mingjia WANG Wenqi li Dong liU zhanbin Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy and Power EngineeringXi’an Jiaotong UniversityXi'an710049China

Printed Circuit Heat Exchanger(PCHE) with high-efficiency and compact structure has great application prospect in the supercritical carbon dioxide(S-CO_(2)) power systems for the next generation of high-temperature concentrated solar and advanced nuclear energy. However, the high operating temperature and pressure require PCHE to maintain good heat transfer performance, as well as reliable mechanical performance at the same time. It is necessary to carry out the fluid-thermal-mechanical coupled analysis of PCHE for the safe and efficient operation of the S-CO_(2) cycle. In this paper, a three-dimensional fluid-structure coupled numerical model was established to study the fluid-thermal-mechanical coupled characteristics of PCHE under different airfoil fin arrangements. The stress distribution of the single airfoil fin was studied, and a better airfoil arrangement that comprehensively considers heat transfer characteristics and stress distribution was obtained. Aiming at the high stress caused by the stress concentration at both ends of the airfoil fin, an optimized configuration combining straight channel and airfoil channel was proposed. The results show that the difference between the flow and heat transfer performance of the two optimized structures and the reference structure is only within 1.5%, but the maximum stresses of the two optimized structures are respectively reduced by 69.4% and 70.0% compared with that of the reference structure, which significantly reduces the stress intensity of PCHE. The result provides a new method to develop the airfoil PCHE with uniform stress distribution and good thermo-hydraulic performance.

关键词： printed circuit heat exchanger supercritical carbon dioxide airfoil fin thermal-mechanical coupling

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Establishment of a sediment transport capacity equation on loessal slope via experimental investigation

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International Journal of Sediment Research 2023年第2期38卷 166-174页

作者： Tian Wang Jingsi li Jingming Hou Peng li Shengdong Cheng Feng Wang Wen Wang Zhanbin LI Reinhard Hinkelmann State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China Xi'an University of Technology Chair of Water Resources Management and Modeling of Hydrosystems Department of Civil Engineering Technische Universit at Berlin Shaanxi Province Institute of Water Resources and Electric Power Investigation and Design Key Laboratory of National Forestry Administration on Ecological Hydrology and Disaster Prevention in Arid Regions Xi'an University of Technology

Areliable sediment transport capacity function provides response against challenges of soil erosion prediction on the Loess Plateau of China. The popular sediment transport capacity functions are questionable on loess slopes because the experimental conditions from which they were derived, like bed materials, gentle slopes,and surface roughness, are different from soil erosion processes on the loess slopes. Due to the foregoing uncertainty, a suitable sediment transport capacity function was developed based on a flume experiment investigation. The erodible bed experiment was implemented for five unit width discharges(1.3 × 10-4-3.3 × 10-4m2/s) and ten slopes(5.2%-57.7%). The selected sediment transport capacity equations were tested in an applicability evaluation. The results of this evaluation found that the Govers(1990) function had the best performance(P.O.0.5-2.0= 76%, R2= 0.93, RMSE = 0.03 kg/(m·s)), followed by the Yalin(1963) function(P.O.0.5-2.0= 80%, R2= 0.81, RMSE = 0.05 kg/(m·s)), and finally by the Low(1989) function(P.O.0.5-2.0= 72%,R2= 0.79, RMSE = 0.04 kg/(m·s)), where P.O.0.5-2.0is the percentage of estimated values with logarithmic discrepancies with the measured value between 0.5 and 2.0; R2is the coefficient of determination and RMSE is the roof mean squares error. The cohesive sediment incipient motion velocity is introduced into the Govers(1990) function, and the sediment particle parameter is determined from measured experimental data. The developed sediment transport capacity equation has good performance with predicted values corresponding to measured values(P.O.0.5-2.0= 98%, R2= 0.98, RMSE = 0.006 kg/(m·s)). The research results provide an improved sediment transport capacity function on the basis of experiments for steep loessal slopes.

关键词： Experimental investigation Hydraulic conditions Loessal slope Sediment transport capacity

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Transport mechanism of eroded sediment particles under freeze-thaw and runoff conditions

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Journal of Arid Land 2022年第5期14卷 490-501页

作者： WANG Tian li Peng HOU Jingming TONG Yu li Jing WANG Feng li zhanbin State Key Laboratory of Eco-hydraulics in Northwest Arid Region Xi'an University of TechnologyXi'an 710048China Key Laboratory of National Forestry Administration on Ecological Hydrology and Disaster Prevention in Arid Regions Xi'an University of TechnologyXi'an 710048China

Hydraulic erosion associated with seasonal freeze-thaw cycles is one of the most predominant factors,which drives soil stripping and transportation.In this study,indoor simulated meltwater erosion experiments were used to investigate the sorting characteristics and transport mechanism of sediment particles under different freeze-thaw conditions(unfrozen,shallow-thawed,and frozen slopes)and runoff rates(1,2,and 4 L/min).Results showed that the order of sediment particle contents was silt>sand>clay during erosion process on unfrozen,shallow-thawed,and frozen slopes.Compared with original soils,clay and silt were lost,and sand was deposited.On unfrozen and shallow-thawed slopes,the change of runoff rate had a significant impact on the enrichment of clay,silt,and sand particles.In this study,the sediment particles transported in the form of suspension/saltation were 83.58%–86.54%on unfrozen slopes,69.24%–84.89%on shallow-thawed slopes,and 83.75%–87.44%on frozen slopes.Moreover,sediment particles smaller than 0.027 mm were preferentially transported.On shallow-thawed slope,relative contribution percentage of suspension/saltation sediment particles gradually increased with the increase in runoff rate,and an opposite trend occurred on unfrozen and frozen slopes.At the same runoff rate,freeze-thaw process had a significant impact on the relative contribution percentage of sediment particle transport via suspension/saltation and rolling during erosion process.The research results provide an improved transport mechanism under freeze-thaw condition for steep loessal slopes.

关键词： freeze-thaw runoff conditions erosion process sediment particles transport mechanism

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Effects of sediment characteristics on the sediment transport capacity of overland flow

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International Soil and Water Conservation Research 2023年第1期11卷 75-85页

作者： Chenguang liu Suhua Fu Zhanbin LI Zeyu Zhang Jianhui Zeng Institute of Soil and Water Conservation Northwest A&F UniversityYanglingShaanxi712100PR China State Key Laboratory of SoilErosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationChinese Academy of Sciences and Ministry of Water ResourceYanglingShaanxi712100PR China Beijing Key Laboratory of Environmental Remote Sensing and Digital City Faculty of Geographical ScienceBejing Normal UniversityBejing100875PR China

The transport of sediments is a crucial part of soil erosion.Accurately calculating the sediment transport capacity is key to the construction of soil erosion process models.Research on Tc has focused mainly on the dynamics of a single particle of sediment and hydraulic variables.There have been few studies of the impact of soil aggregates on the Tc.To clarify how sediment characteristics,including those for single particles and aggregates,affect the Tc of overland flow with no raindrop import,flume experiments were implemented at slope gradients varying from 5.24%to 26.80%and flow discharges ranging from 0.68 to 5.41×10^(-3)m^(2)s^(-1).The experimental materials were five typical soils in China.The results indicated that the correlation between the measured Tc and sediment mechanical composition indexes of the five soils was indistinctive in this study.The sediment settling velocity with aggregates has a significant corre-lation with the measured Tc.New equations,including for the sediment settling velocity with aggregatesωud75,were established to calculate the Tc.The empirical equation that includedωud75,slope gradient and unit discharge performed greatly in predicting Tc(R^(2)=0.93,NSE=0.90).ωud75 can effectively improve the calculation accuracy of Tc.The new equation including flow and sediment properties obtained through dimensional analysis performed well in predicting Tc(R^(2)=0.99,NSE=0.91),and the calculation accuracy was better than that of the empirical model derived in this study.These findings indicate that the sediment settling velocity is an important variable in the equation for predicting sediment transport capacity of overland flow.

关键词： Sediment transport capacity Soil mechanical composition Soil aggregates Sediment settling velocity Dimensional analysis

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An improved constant volume cycle model for performance analysis and shape design of PDRE nozzle

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Applied Mathematics and Mechanics(English Edition) 2018年第2期39卷 193-206页

作者： Guangyu li Xiaowei li Jue DING Peifen WENG zhanbin LU Shanghai Institute of Applied Mathematics and Mechanics Shanghai University

An improved constant volume cycle （CVC） model is developed to analyze the nozzle effects on the thrust and specific impulse of pulse detonation rocket engine （PDRE）. Theoretically, this model shows that the thrust coefficient/specific impulse of PDRE is a function of the nozzle contraction/expansion ratio and the operating frequency. The relationship between the nozzle contraction ratio and the operation frequency is obtained by introducing the duty ratio, by which the key problem in the theoretical design can be solved. Therefore, the performance of PDRE can be accessed to guide the preliminary shape design of nozzle conveniently and quickly. The higher the operating frequency of PDRE is, the smaller the nozzle contraction ratio should be. Besides, the lower the ambient pressure is, the larger the expansion ratio of the nozzle should be. When the ambient pressure is 1.013 × 105 Pa, the optimal expansion ratio will be less than 2.26. When the ambient pressure is reduced to vacuum, the extremum of the optimal thrust coefficient is 2.236 9, and the extremum of the specific impulse is 321.01 s. The results of the improved model are verified by numerical simulation.

关键词： pulse detonation rocket engine （PDRE） nozzle specific impulse thrust,constant volume cycle （CVC） model

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Determination of Coumoxystrobin Residues in Milk

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Agricultural Biotechnology 2021年第5期10卷 12-13,36页

作者： Meijuan ZHENG Zhanbin LI Yaohong liU Qing li Guizhou Academy of Testing and Analysis Guiyang 550013China GRG Metrology&Test(Hunan)Co. Ltd.Changsha 410013China

[Objectives]This study was conducted to establish a liquid chromatography-tandem mass spectrometry method for the determination of coumoxystrobin residue in milk.[Methods]A sample was ultrasonically extracted with acetonitrile,purified by a solid phase extraction column,concentrated by nitrogen blowing,and tested on a machine.[Results]In the range of 0.01-10.00 mg/kg,the linear relationship of coumoxystrobin was good.The linear equation was y=5045.96x+935.332,r^(2)=0.999.The detection limit was 0.002 mg/kg,and the quantitation limit was 0.006 mg/kg.The method has good stability,high precision,and the detection limit can meet the limit requirement of coumoxystrobin in GB 2763-2019.[Conclusions]This study can provide technical support for the supervision and monitoring of coumoxystrobin.

关键词： Milk Coumoxystrobin Residue Determination

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Distribution characteristics of available trace elements in soil from a reclaimed land in a mining area of north Shaanxi,China

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International Soil and Water Conservation Research 2013年第1期1卷 65-75页

作者： li zhanbin Zhang Qinling li Peng Key Lab of Northwest Water Resources and Environment Ecology of MOE Xi'an University of Technology Xi'an 710048ShaanxiP.R.China State Key Laboratory of Soil Erosion and Dry-land Farming on the Lous Plateau Institute of Soil and Water ConservationChinese Academy of SciencesYangling 712100ShaanxiP.R.China Soil and Water Conservation Bureau in Shaanxi Province Xi'an 710042ShaanxiP.R.China

Through field and laboratory tests we studied the temporal and spatial variation in the soil content of four available trace elements:copper(Cu),iron(Fe),manganese(Mn)and zinc(Zn),to analyze their distribution characteristics in reclaimed mining land under different reclamation conditions.The available trace elements content varied considerably with different land reclamation patterns.Extended reclamation time was helpful for the recovery of the available trace element content in the soil,and after more than eight years of soil reclamation,the content of available trace elements was closer to or greater than that in soil under natural conditions.Various treatment measures significantly influenced the content and distribution of available trace elements in the soil,and reasonable artificial treatments,including covering the soil and growing shrubs and herbaceous plants,increased the content of available trace elements.

关键词： Available trace element Reclaimed land Reclamation time Treatment measure Mining area

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Has“Grain for Green”threaten food security on the Loess Plateau of China?

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Ecosystem Health and Sustainability 2020年第1期6卷 368-380,367页

作者： Peng Shi Zhaohong Feng Haidong Gao Peng li Xiaoming Zhang Tiantian Zhu Zhanbin LI Guoce Xu Zongping Ren lie Xiao State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China Xi’an University of TechnologyXi’anChina State Key Laboratory Base of Eco-hydraulic Engineering in Arid Area Xi’an University of TechnologyXi’anChina Department of Sediment Research China Institute of Water Resources and Hydropower ResearchBeijingChina College of Architecture Xi’an University of Architecture and TechnologyXi’anChina

There is debating over the question of whether the large-scale‘Grain for Green’program on the Loess Plateau of China threatens regional food security.Self-sufficiency index and cropland pressure index were used to assess food security on the Loess Plateau after the implementation of revegetation program.The results showed that the‘Grain for Green’program initially had a considerable impact on regional food security,where grain yield fell from 1999 to 2001,resulting in a lower grain self-sufficiency and increased farmland stress.Subsequently,grain yield in this region increased due to the elevated agricultural material input and increased construction of terraces and check dams.The grain self-sufficiency index would have increased to 96.55%if there were improvements to the agricultural conditions,such as fertilization and irrigation,which would have resulted in an increase in the crop yield per unit of 20%.However,the grain self-sufficiency increased to 105.25%via the construction of terraces and check dams.Thus,the government should further expand the‘Grain for Green’program in coordination with improvements to the agricultural production conditions and the construction of terraces and check dams on the Loess Plateau.

关键词： Agricultural production condition Grain for Green food security terrace and check dam construction

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