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| 1 | Soil erosion and sediment interception by check dams in a watershed for an extreme rainstorm on the Loess Plateau,China显示文摘The magnitude of soil erosion and sediment load reduction efficiency of check dams under extreme rainstorms is a long-standing concern.The current paper aims to use check dams to deduce the amount of soil erosion under extreme rainstorms in a watershed and to identify the difference in sediment interception efficiency of different types of check dams.Based on the sediment deposition at 12 check dams with 100% sediment interception efficiency and sub-catchment clustering by taking 12 damcontrolled catchments as clustering criteria,the amount of soil erosion resulting from an extreme rainstorm event on July 26,2017(named '7·26' extreme rainstorm) was estimated in the Chabagou watershed in the hill and gully region of the Loess Plateau.The differences in the sediment interception efficiency among the check dams in the watershed were analyzed according to field observations at 17 check dams.The results show that the average erosion intensity under the '7-26' extreme rainstorm was approximately 2.03×10~4 t/km^2,which was 5 times that in the second largest erosive rainfall in 2017(4.15×10~3 t/km^2) and 11-384 times that for storms in 2018(0.53×10~2 t/km^2-1.81×10~3 t/km^2).Under the '7-26' extreme rainstorm,the amount of soil erosion in the Chabagou watershed above the Caoping hydrological station was 4.20 × 106 t.The sediment interception efficiency of the check dams with drainage canals(including the destroyed check dams) and with drainage culverts was 6.48 and 39.49%,respectively.The total actual sediment amount trapped by the check dams was 1.11 × 106 t,accounting for 26.36% of the total amount of soil erosion.In contrast,3.09×106 t of sediment were input to the downstream channel,and the sediment deposition in the channel was 2.23×10~6 t,accounting for 53.15%of the total amount of soil erosion.The amount of sediment transport at the hydrological station was8.60×10~5 t.The Sediment Delivery Ratio(SDR) under the '7·26' extreme rainstorm was 0.21.The results indicated that the amount of soil erosion was huge,and the sediment interception efficiency of the check dams was greatly reduced under extreme rainstorms.It is necessary to strengthen the management and construction technology standards of check dams to improve the sediment interception efficiency and flood safety in the watershed. | Leichao Bai Nan Wang Juying Jiao Yixian Chen Bingzhe Tang Haolin Wang Yulan Chen Xiqin Yan Zhijie Wang | 2020 | International Journal of Sediment Research2020，35，4： | 7 |
| 2 | Combined proportional navigation law for interception of high-speed targets显示文摘A new proportional navigation(PN) guidance law,called combined proportional navigation(CPN),is proposed.The guidance law is designed to intercept high-speed targets,which is a common case for ballistic targets.The range of target-to-interceptor speed ratio during target interception is derived when guidance laws are applied in high-speed targets interception,and the effectiveness of negative navigation ratio in the PN-based guidance law is proven analytically in some lemmas.Based on the lemmas,the lateral acceleration command of CPN is defined,and the solution to the appearance of singularity in time-varying navigation ratio is given.The simulation results show that CPN can determine headon engagement(as PN) or tail-chase engagement(as RPN) through initial path angle compared with PN and retro proportional navigation(RPN),and can adjust the value of navigation ratio for head-on engagement or tail-chase engagement.Therefore,the capture region of CPN is larger than that of other guidance laws using PN-based methods. | Yuan LI Liang YAN Ji-guang ZHAO Fan LIU Tao WANG | 2014 | Defence Technology(防务技术)2014，10，3： | 4 |
| 3 | 植被冠层和坡位对长江三峡山地小流域降雨过程土壤水分响应的影响显示文摘Rainfall provides essential water resource for vegetation growth and acts as driving force for hydrologic process,bedrock weathering and nutrient cycle in the steep hilly catchment.But the effects of rainfall features,vegetation types,topography,and also their interactions on soil water movement and soil moisture dynamics are inadequately quantified.During the coupled wet and dry periods of the year 2018 to 2019,time-series soil moisture was monitored with 5-min interval resolution in a hilly catchment of the Three Gorges Reservoir Area in China.Three hillslopes covered with evergreen forest(EG),secondary deciduous forest mixed with shrubs(SDFS)and deforested pasture(DP)were selected,and two monitoring sites with five detected depths were established at upslope and downslope position,respectively.Several parameters expressing soil moisture response to rainfall event were evaluated,including wetting depth,cumulative rainfall amount and lag time before initial response,maximum increase of soil water storage,and transform ratio of rainwater to soil water.The results indicated that rainfall amount is the dominant rainfall variable controlling soil moisture response to rainfall event.No soil moisture response occurred when rainfall amounts was<8 mm,and all the deepest monitoring sensors detected soil moisture increase when total rainfall amounts was>30 mm.In the wet period,the cumulative rainfall amount to trigger surface soil moisture response in EG-up site was significantly higher than in other five sites.However,no significant difference in cumulative rainfall amount to trigger soil moisture response was observed among all study sites in dry period.Vegetation canopy interception reduced the transform ratio of rainwater to soil water,with a higher reduction in vegetation growth period than in other period.Also,interception of vegetation canopy resulted in a larger accumulated rainfall amount and a longer lag time for initiating soil moisture response to rainfall.Generally,average cumulative rainfall amount for initiating soil moisture response during dry period of all sites(3.5-5.6 mm)were less than during wet period(5.7-19.7 mm).Forests captured more infiltration water compared with deforested pasture,showing the larger increments of both soil water storage for the whole soil profile and volumetric soil water content at 10 cm depth on two forest slopes.Topography dominated soil subsurface flow,proven by the evidences that less rainfall amount and less time was needed to trigger soil moisture response and also larger accumulated soil water storage increment in downslope site than in corresponding upslope site during heavy rainfall events. | 刘目兴 王秋月 郭立 易军 林杭生 朱青 范碧航 张海林 | 2020 | Journal of Geographical Sciences2020，30，6： | 4 |
| 4 | Experimental Evaluation of Certain Pursuit and Evasion Schemes for Wheeled Mobile Robots显示文摘Pursuit-evasion games involving mobile robots provide an excellent platform to analyze the performance of pursuit and evasion strategies. Pursuit-evasion has received considerable attention from researchers in the past few decades due to its application to a broad spectrum of problems that arise in various domains such as defense research, robotics, computer games, drug delivery, cell biology, etc. Several methods have been introduced in the literature to compute the winning chances of a single pursuer or single evader in a two-player game. Over the past few decades, proportional navigation guidance (PNG) based methods have proved to be quite effective for the purpose of pursuit especially for missile navigation and target tracking. However, a performance comparison of these pursuer-centric strategies against recent evader-centric schemes has not been found in the literature, for wheeled mobile robot applications. With a view to understanding the performance of each of the evasion strategies against various pursuit strategies and vice versa, four different proportional navigation-based pursuit schemes have been evaluated against five evader-centric schemes and vice-versa for non-holonomic wheeled mobile robots. The pursuer′s strategies include three well-known schemes namely, augmented ideal proportional navigation guidance (AIPNG), modified AIPNG, angular acceleration guidance (AAG), and a recently introduced pursuer-centric scheme called anticipated trajectory-based proportional navigation guidance (ATPNG). Evader-centric schemes are classic evasion, random motion, optical-flow based evasion, Apollonius circle based evasion and another recently introduced evasion strategy called anticipated velocity based evasion. The performance of each of the pursuit methods was evaluated against five different evasion methods through hardware implementation. The performance was analyzed in terms of time of interception and the distance traveled by players. The working environment was obstacle-free and the maximum velocity of the pursuer was taken to be greater than that of the evader to conclude the game in finite time. It is concluded that ATPNG performs better than other PNG-based schemes, and the anticipated velocity based evasion scheme performs better than the other evasion schemes. | Amit Kumar Aparajita Ojha | 2019 | International Journal of Automation and computing2019，16，4： | 3 |
| 5 | Optimal terminal guidance for exoatmospheric interception显示文摘In this study, two optimal terminal guidance(OTG) laws, one of which takes into account the final velocity vector constraint, are developed for exoatmospheric interception using optimal control theory. In exoatmospheric interception, because the proposed guidance laws give full consideration to the effect of gravity, they consume much less fuel than the traditional guidance laws while requiring a light computational load. In the development of the guidance laws, a unified optimal guidance problem is put forward, where the final velocity vector constraint can be considered or neglected by properly adjusting a parameter in the cost function. To make this problem analytically solvable, a linear model is used to approximate the gravity difference, the difference of the gravitational accelerations of the target and interceptor. Additionally, an example is provided to show that some achievements of this study can be used to significantly improve the fuel efficiency of the pulsed guidance employed by the interceptor whose divert thrust level is fixed. | Yu Wenbin Chen Wanchun Yang Liang Liu Xiaoming Zhou Hao | 2016 | Chinese Journal of Aeronautics2016，29，4： | 3 |
| 6 | Genotypic variation in spatiotemporal distribution of canopy light interception in relation to yield formation in cotton显示文摘Background: Within-canopy interception of photosynthetically active radiation(PAR) impacts yield and other agronomic traits in cotton(Gossypium hirsutum L.). Field experiments were conducted to investigate the influence of 6 cotton varieties(they belong to 3 different plant types) on yield, yield distribution, light interception(LI), LI distribution and the relationship between yield formation and LI in Anyang, Henan, in 2014 and 2015.Result: The results showed that cotton cultivars with long branches(loose-type) intercepted more LI than did cultivars with short branches(compact-type), due to increased LI in the middle and upper canopy. Although loose-type varieties had greater LI, they did not yield significantly higher than compact-type varieties, due to decreased harvest index. Therefore, improving the harvest index by adjusting the source-to-sink relationship may further increase cotton yield for loose-type cotton. In addition, there was a positive relationship between reproductive organ biomass accumulation and canopy-accumulated LI, indicating that enhancing LI is important for yield improvement for each cultivar. Furthermore, yield distribution within the canopy was significantly linearly related to vertical LI distribution.Conclusion: Therefore, optimizing canopy structure of different plant type and subsequently optimizing LI distribution within the cotton canopy can effectively enhance the yield. | XING Fangfang HAN Yingchun FENG Lu ZHI Xiaoyu WANG Guoping YANG Beifang FAN Zhengyi LEI Yaping DU Wenli WANG Zhanbiao XIONG Shiwu LI Xiaofei Ll Yabing | 2018 | Journal of Cotton Research2018，1，3： | 3 |
| 7 | CFD Simulation of the Filtration Performance of Fibrous Filter Considering Fiber Electric Potential Field显示文摘Aiming at disclosing the quantitative e ects of Coulomb forces on the ltration e ciency of aerosol particles, a three- dimensional random ber model was established to describe the microstructure of brous lters. Then, computational mod- els including the ow model, particle model, and electric eld model were constructed to estimate the ltration e ciency using the Fluent custom user-de ned function program, neglecting the non-uniformity of the ber potential and the particle charge distribution. The simulation results using the established models agreed with the data in the literature. In particular, the electric eld force was found to be one of the important factors required to improve the ltration e ciency estimation accuracy for the ultra ne particles. Moreover, the variation tendencies of the ltration e ciency and the pressure drop of brous lters were studied based on the in uence factors of the ber potential, particle charge-to-mass ratio, solid volume fraction, ber diameter, and face velocity. The established models and estimated results will provide important guidance on the design of high-e ciency particulate air lters for aerosol particles. | Lei Hou Ayang Zhou Xiao He Wei Li Yan Fu Jinli Zhang | 2019 | Transactions of Tianjin University2019，25，5： | 1 |
| 8 | 黑河流域典型生态系统的降雨截留特征——基于高时间分辨率的土壤水分数据(英文)显示文摘Rainfall interception is of great significance to the fully utilization of rainfall in water limited areas.Until now,studies on rainfall partitioning process of typical ecosystems in Heihe River Basin,one of the most important inland river basins in China,is still insufficient.In this study,six typical ecosystems were selected,namely alpine meadow,coniferous forest,mountain steppe,desert,cultivated crop,and riparian forest,in Heihe River Basin for investigation of the rainfall interception characteristics and their influencing factors,including rainfall amount,duration,and intensity,based on the gross rainfall and high temporal resolution soil moisture data obtained from 12 automatic observation sites.The results show that the average interception amount and average interception rate of the six ecosystems are significantly different: alpine meadow 6.2 mm and 45.9%,coniferous forest 7.4 mm and 69.1%,mountain steppe 3.5 mm and 37.3%,desert 3.5 mm and 57.2%,cultivated crop 4.5 mm and 69.1%,and riparian forest 2.6 mm and 66.7%,respectively.The rainfall amount,duration,and intensity all had impact on the process of rainfall interception.Among these three factors,the impact of rainfall amount was most significant.The responses of these ecosystems to the rainfall characteristics were also different.Analyzing rainfall interception with high temporal resolution soil moisture data is proved to be a feasible method and need further development in the future. | 杨崇曜 黄永梅 李恩贵 李泽卿 | 2019 | Journal of Geographical Sciences2019，29，9： | 1 |
| 9 | STUDY ON RETAINING FUNCTION OF LARCH PLANTATION显示文摘Based on the data accumulated through two year research work forest hydrology study was conducted at Lao Shan plantation experimental station of Maoer Shan Forest Farm.The experiment reuslts on detention of precipitation, permeability of stand soil water holding capacity, formation and regulation of runoff are discussed in the this paper. The major results in this study are as follows: (1)the function of forest in intercepting and storing rainwater is the outcome of integrating action of stand and soli, while the thickness of soil layers is the important factor which affects the water intercepting and holding capacity of forest. (2)The larch forest land had higher permeability, its stable infiltration velocity is twice as much as that of grassland. (3) It is proved that the interflow and groundwater runoff are the major forms of runoff occured in larch forest land. | 蔡体久 刘亚范 | 1995 | Journal of Northeast Forestry University1995，6，1： | 0 |
| 10 | Snow depth simulated by BATS-SAST model and its improvement显示文摘A BATS-SAST model was employed to simulate the snow processes in four snow cases of Sk_OJP 2001/2002, 2002/2003, 2003/2004 and Sk_HarvestJP 2003/2004 of Canada. At Sk_OJP site we modified the long-wave radiation and precipitation schemes. Considering the different interceptions between rain and snow and the effect of wind and canopy temperature on snow download, we improved the canopy interception model. At Sk_HarvestJP site we modified the snow cover fraction scheme. Results show that the model reasonably simulates the basic processes of snow cover. The modified model, which considers the part of the long-wave radiation and precipitation transmitted through the canopy at Sk_OJP site, can increase the simulation of snow depth which is closer to the observations. The improved canopy interception model, which influences the variation of snow depth under the canopy by changing canopy interception, is a great improvement on simulation of snow depth, especially on the ablation of snow cover. At Sk_HarvestJP site, there are obvious improvements on simulation of snow depth on the ablation of snow cover. | Kun Xia Yong Luo WeiPing Li | 2010 | Research in Cold and Arid Regions2010，2，4： | 0 |
| 11 | On Electromagnetic Scattering Features of Geological Radar Targets显示文摘The electromagnetic scattering principles of geological radar targets and various influential factors were discussed, and the importance of researching into the electromagnetic scattering features of the targets to the actual prospecting task was pointed out. | 李大洪 | 2000 | International Journal of Mining Science and Technology2000，21，1： | 0 |
| 12 | Study on Litter Water Interception Capacity of Phyllostachys edulis Plantations with Different Densities显示文摘The litter amount and the water holding characteristic parameters,such as the maximum water holding capacity and rate,the water absorption rate and the modified interception amount of Phyllostachys edulis plantations with four densities were studied in Huangshan district.The results are as follows:The total amount,thickness and natural water content of litters under all the four stands tested were different.The total litter amount in different stands ranged between 3.98 t·ha-1 to 6.00 t·ha-1, which in the stand with the density of 3 000 stems·ha-1 was the most.The ratio of maximum water-holding capacity of litter in various stands ranged from 317.09%to 347.58%.The maximum water holding capacity of litter in the stand with the density of 3 000 stems·ha-1 was 20.70 t·ha-1. By analyzing,the relationship between the water holding capacity of litter and the immersion time followed the equation of:S = alnt + b(a is the coefficient;b is the constant term).The relationship between the water absorption speed of the litter and the immerse time followed the equation of: V = ctd(c is the coefficient;d is the exponential term).The litter water capacity increased rapidly within the first four hours,and then increased slowly.The results also showed that the hydrological character of litter was positively related to density in Ph.Edulis forest.Therefore, it is important to choose appropriate density for enhancing the eco-hydrological benefits of litter layer in Ph.edulis forest. | Yu Lin Fan Shaohui Su Wenhui LiuWeiyi Feng Huanying | 2012 | Chinese Forestry Science and Technology2012，11，3： | 0 |
| 13 | 黄土沟壑区柠条水保林生态经济效益调查研究显示文摘黄土沟壑区柠条水保林生态经济效益调查研究屈振丰,赵有来(河北省尚义县职教中心,076750)(尚义县林业局)冀西北黄土沟壑区地处河北省西北部,包括张家口市坝下万全、怀安等县及尚义县坝下部分,为首都周围造林绿化工程西段,是河北省一特殊造林区域。该区域海... | 屈振丰 赵有来 | 1996 | 河北林果研究1996，11，S1： | 0 |
| 14 | Maximal admissible mode decision delay in terminal guidance显示文摘Mode decision-maker is a critical component in the logic-based Integrated Estimation and Guidance(IEG) system. For the best possible estimation and guidance performance, the mode decision delay of the mode decision-maker should be limited to a range as small as possible. This paper presents a numerical method for computing the maximal admissible mode decision delay that varies with time-to-go. Particular attention has been paid to highly maneuvering target interception in terminal guidance. The results of this research offer useful guidelines for the design of the mode decision-maker in IEG systems. | Shengwen XIANG Tiancheng LI Wei CHEN Hongqi FAN Qiang FU | 2019 | Chinese Journal of Aeronautics2019，32，8： | 0 |
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