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Coupling of a Regional Climate Model with a Crop Development Model and Evaluation of the Coupled Model across China 预览
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作者 Jing ZOU Zhenghui XIE +4 位作者 Chesheng ZHAN Feng CHEN Peihua QIN Tong HU Jinbo XIE 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第5期527-540,共14页
In this study,the CERES(Crop Estimation through Resource and Environment Synthesis)crop model was coupled with CLM3.5,the land module of the regional climate model RegCM4.The new coupled model was named RegCM4 CERES;a... In this study,the CERES(Crop Estimation through Resource and Environment Synthesis)crop model was coupled with CLM3.5,the land module of the regional climate model RegCM4.The new coupled model was named RegCM4 CERES;and in this model,crop type was further divided into winter wheat,spring wheat,spring maize,summer maize,early rice,late rice,single rice,and other crop types based on each distribution fraction.The development of each crop sub-type was simulated by the corresponding crop model separately,with each planting and harvesting date.A simulation test using RegCM4 CERES was conducted across China from 1999 to 2008;a control test was also performed using the original RegCM4.Data on crop LAI(leaf area index),soil moisture at 10 cm depth,precipitation,and 2 m air temperature were collected to evaluate the performance of RegCM4 CERES.The evaluation provided comparison of single-station time series,regional distributions,seasonal variations,and statistical indices for RegCM4 CERES.The results revealed that the coupled model had an excellent ability to simulate the phonological changes and spatial variations in crops.The consideration of dynamic crop development in RegCM4 CERES corrected the wet bias of the original RegCM4 over North China and the cold bias over South China.However,the degree of improvement was minimal and the statistical indices for RegCM4 CERES were roughly the same as the original RegCM4. 展开更多
关键词 MODEL EVALUATION MODEL COUPLING CROP development MODEL regional CLIMATE MODEL CLIMATE modeling
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The pig as a preclinical traumatic brain injury model: current models,functional outcome measures,and translational detection strategies 预览
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作者 Holly A.Kinder Emily W.Baker Franklin D.West 《中国神经再生研究:英文版》 SCIE CAS CSCD 2019年第3期413-424,共12页
Traumatic brain injury(TBI) is a major contributor of long-term disability and a leading cause of death worldwide. A series of secondary injury cascades can contribute to cell death, tissue loss, and ultimately to the... Traumatic brain injury(TBI) is a major contributor of long-term disability and a leading cause of death worldwide. A series of secondary injury cascades can contribute to cell death, tissue loss, and ultimately to the development of functional impairments. However, there are currently no effective therapeutic interventions that improve brain outcomes following TBI. As a result, a number of experimental TBI models have been developed to recapitulate TBI injury mechanisms and to test the efficacy of potential therapeutics. The pig model has recently come to the forefront as the pig brain is closer in size, structure, and composition to the human brain compared to traditional rodent models, making it an ideal large animal model to study TBI pathophysiology and functional outcomes. This review will focus on the shared characteristics between humans and pigs that make them ideal for modeling TBI and will review the three most common pig TBI models–the diffuse axonal injury, the controlled cortical impact, and the fluid percussion models. It will also review current advances in functional outcome assessment measures and other non-invasive, translational TBI detection and measurement tools like biomarker analysis and magnetic resonance imaging. The use of pigs as TBI models and the continued development and improvement of translational assessment modalities have made significant contributions to unraveling the complex cascade of TBI sequela and provide an important means to study potential clinically relevant therapeutic interventions. 展开更多
关键词 traumatic brain INJURY large animal MODEL PIG MODEL diffuse AXONAL INJURY FUNCTIONAL outcome assessment measures controlled cortical impact MODEL fluid percussion INJURY MODEL magnetic resonance imaging biomarkers
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Three Evolutions of the Landscape Cognitive Model from the Perspective of Philosophy 预览
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作者 ZHAO Meihong 《景观研究:英文版》 2019年第3期78-81,共4页
Looking back at the history of landscape design, there are various styles and schools as well as numerous design concepts. From the perspective of philosophical epistemology, landscape design has experienced three per... Looking back at the history of landscape design, there are various styles and schools as well as numerous design concepts. From the perspective of philosophical epistemology, landscape design has experienced three periods, namely, apriorism, empiricism and transcendentalism. Combining the design phenomena in the history of garden design, this paper sorted out the evolution of landscape design in terms of methodology, epistemology and instrumentalism, in order to speculate on the macroscopic trajectory of the evolution of landscape cognitive model. 展开更多
关键词 A priori MODEL EMPIRICISM MODEL TRANSCENDENTALISM MODEL
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A dual timescale model for micro-mixing and its application in LES-TPDF simulations of turbulent nonpremixed flames
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作者 Fang WANG Rui LIU +2 位作者 Li DOU Denghuan LIU Jie JIN 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第4期875-887,共13页
The numerical simulation of modern aero-engine combustion chamber needs accurate description of the interaction between turbulence and chemical reaction mechanism. The Large Eddy Simulation(LES) method with the Transp... The numerical simulation of modern aero-engine combustion chamber needs accurate description of the interaction between turbulence and chemical reaction mechanism. The Large Eddy Simulation(LES) method with the Transported Probability Density Function(TPDF) turbulence combustion model is promising in engineering applications. In flame region, the impact of chemical reaction should be considered in TPDF molecular mixing model. Based on pioneer research, three new TPDF turbulence-chemistry dual time scale molecular mixing models were proposed tentatively by adding the chemistry time scale in molecular mixing model for nonpremixed flame. The Aero-Engine Combustor Simulation Code(AECSC) which is based on LES-TPDF method was combined with the three new models. Then the Sandia laboratory’s methane-air jet flames: Flame D and Flame E were simulated. Transient simulation results show that all the three new models can predict the instantaneous combustion flow pattern of the jet flames. Furthermore,the average scalar statistical results were compared with the experimental data. The simulation result of the new TPDF arithmetic mean modification model is the closest to the experimental data:the average error in Flame D is 7.6% and 6.6% in Flame E. The extinction and re-ignition phenomena of the jet flames especially Flame E were captured. The turbulence time scale and the chemistry time scale are in different order in the whole flow field. The dual time scale TPDF combustion model has ability to deal with both the turbulence effect and the chemistry reaction effect, as well as their interaction more accurately for nonpremixed flames. 展开更多
关键词 DUAL TIME scale MODEL Large EDDY simulation Sandia methane-air jet ?ame TPDF molecular mixing MODEL Turbulence combustion MODEL
我国动力煤期货市场的价格发现效率测度
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作者 邹绍辉 马婷艳 田倍诚 《煤炭经济研究》 2019年第2期12-19,共8页
选取我国供给侧改革前后的两年期动力煤期货和现货价格日数据,以VECM模型为基础,创新性地使用信息份额IS模型,最新修正信息份额MIS模型以及永久短暂PT模型,对我国动力煤期现货市场受到短期内和长期内的新信息冲击时的价格发现效率进行... 选取我国供给侧改革前后的两年期动力煤期货和现货价格日数据,以VECM模型为基础,创新性地使用信息份额IS模型,最新修正信息份额MIS模型以及永久短暂PT模型,对我国动力煤期现货市场受到短期内和长期内的新信息冲击时的价格发现效率进行实证研究并比较。结果表明:当我国动力煤期货市场受到短期内的新信息冲击时,供给侧改革后的期货价格发现效率更高,对现货市场的引导作用较强,效果更显著、持久;当我国动力煤期货市场受到长期内的新信息冲击时,供给侧改革前的期货价格发现效率更高,与现货市场为单向因果关系;整体而言,我国动力煤期货市场的价格发现效率高于现货市场,处于核心地位。 展开更多
关键词 动力煤期货 价格发现 IS模型 MIS模型 PT模型
An experimental method for quantitative analysis of real contact area based on the total reflection optical principle
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作者 罗治军 宋保江 +1 位作者 韩靖宇 阎绍泽 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期158-165,共8页
The simulation of real contact area between materials is foundationally important for the contact mechanics of mechanical structures.The Greenwood and Williamson (GW) model and the Majumdar (MB) model are the basic mo... The simulation of real contact area between materials is foundationally important for the contact mechanics of mechanical structures.The Greenwood and Williamson (GW) model and the Majumdar (MB) model are the basic models in this field,which are widely accepted and proven to be valid in many experiments and engineering.Although the contact models have evolved considerably in recent years,the verifications of the models are most based on the indirect methods such as electrical conductivity and contact stiffness,because of the lack of effective methods to directly measure the variation of contact surface.In this paper,the total reflection (TR) method is introduced into the verification of contact models.An experiment system based on TR method is constructed to measure the real contact area of two PMMA specimens.The comparison analysis between the results of experiment and models suggests that the experiment result has the same trend with simulation,the MB model has better agreement with the experimental result because this method can take into account the variation of radius and the merging of asperities,while the GW model has a huge deviation because of the dependence on resolution and the lack of considering the variation of radius and asperity’s merging process.Taking the interaction of asperities into account could give a better result that is closer to the experiment.Our results and analysis prove that the experimental methods in this paper could be used as a more direct and valid method to quantitatively measure the real contact area and to verify the contact models. 展开更多
关键词 REAL contact area Greenwood and WILLIAMSON (GW) MODEL Majumdar (MB) MODEL Persson’s MODEL total REFLECTION (TR) method
GIS-based landslide susceptibility mapping using numerical risk factor bivariate model and its ensemble with linear multivariate regression and boosted regression tree algorithms
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作者 Alireza ARABAMERI Biswajeet PRADHAN +2 位作者 Khalil REZAE Masoud SOHRABI Zahra KALANTARI 《山地科学学报:英文版》 SCIE CSCD 2019年第3期595-618,共24页
In this study, a novel approach of the landslide numerical risk factor(LNRF) bivariate model was used in ensemble with linear multivariate regression(LMR) and boosted regression tree(BRT) models, coupled with radar re... In this study, a novel approach of the landslide numerical risk factor(LNRF) bivariate model was used in ensemble with linear multivariate regression(LMR) and boosted regression tree(BRT) models, coupled with radar remote sensing data and geographic information system(GIS), for landslide susceptibility mapping(LSM) in the Gorganroud watershed, Iran. Fifteen topographic, hydrological, geological and environmental conditioning factors and a landslide inventory(70%, or 298 landslides) were used in mapping. Phased array-type L-band synthetic aperture radar data were used to extract topographic parameters. Coefficients of tolerance and variance inflation factor were used to determine the coherence among conditioning factors. Data for the landslide inventory map were obtained from various resources, such as Iranian Landslide Working Party(ILWP), Forestry, Rangeland and Watershed Organisation(FRWO), extensive field surveys, interpretation of aerial photos and satellite images, and radar data. Of the total data, 30% were used to validate LSMs, using area under the curve(AUC), frequency ratio(FR) and seed cell area index(SCAI).Normalised difference vegetation index, land use/land cover and slope degree in BRT model elevation, rainfall and distance from stream were found to be important factors and were given the highest weightage in modelling. Validation results using AUC showed that the ensemble LNRF-BRT and LNRFLMR models(AUC = 0.912(91.2%) and 0.907(90.7%), respectively) had high predictive accuracy than the LNRF model alone(AUC = 0.855(85.5%)). The FR and SCAI analyses showed that all models divided the parameter classes with high precision. Overall, our novel approach of combining multivariate and machine learning methods with bivariate models, radar remote sensing data and GIS proved to be a powerful tool for landslide susceptibility mapping. 展开更多
关键词 LANDSLIDE susceptibility GIS Remote sensing BIVARIATE MODEL MULTIVARIATE MODEL Machine learning MODEL
Modeling aggregate size distribution of eroded sediment resulting from rain-splash and raindrop impacted flow processe 预览
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作者 Selen Deviren Saygin Gunay Erpul 《国际泥沙研究:英文版》 SCIE 2019年第2期166-177,共12页
Soil susceptibility to detachment and transport sub-processes of erosion is generally controled by the aggregate breakdown mechanism. Measuring particle size and aggregation to the estimate erodibility potential of so... Soil susceptibility to detachment and transport sub-processes of erosion is generally controled by the aggregate breakdown mechanism. Measuring particle size and aggregation to the estimate erodibility potential of soils is important under erosive rainfall conditions. The Aggregate Size Distribution (ASD) is one of the most important determinants of soil structure along with soil organic matter content for describing the efficiency of applied, sustainable management strategies. This study aimed to compare the performances of three different aggregate size distribution models to predict the characteristic aggregate size parameter (median diameter, D50) for eroded sediment from interrill erosion processes of Rain- Splash Transport (RST) and Raindrop Impacted Flow Transport (RIFT). The ASDs of 1143 collected sediment samples from the RST and RIFT processes were measured and modeled by the Log-normal, Fractal, and Weibull approaches. The D50 value, as a characteristic parameter for aggregate size distributions, derived from the cumulative ASD curve was compared for soils from different land use types and different slope and rainfall intensity conditions. The performance of each model was evaluated using the Mean Square Error (MSE) and Coefficient of Determination (R^2). The Weibull approach was the most accurate model showing the best fit with the lowest MSE values (0.0002 ≤MSE≤ 0.0048) and having the greatest R2 values (0.936≤ R^2≤ 0.998) when compared with the Log-normal and Fractal models. Herewith, for semi-arid land use and soil, specific shape and scale parameters for the Weibull distribution, the respective ASDs were successfully re-generated for modeling the eroded sediment of the simulated RST and RIFT interill processes. 展开更多
关键词 AGGREGATE SIZE distribution Eroded SEDIMENT Log-normal MODEL FRACTAL MODEL Weibull MODEL
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An Improved Enthalpy-Based Lattice Boltzmann 3D Model with Added Probability Function for the Growth Characteristics of Frost Layer
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作者 CUI Jing YANG Tinghao +1 位作者 YANG Fan YANG Guangfeng 《热科学学报:英文版》 SCIE EI CAS CSCD 2019年第2期378-392,共15页
In this paper, the effects of different surface properties on the growth of frost layer were numerically studied from the mesoscopic scale using the lattice Boltzmann method. The improved enthalpy method and nucleatio... In this paper, the effects of different surface properties on the growth of frost layer were numerically studied from the mesoscopic scale using the lattice Boltzmann method. The improved enthalpy method and nucleation probability model were combined to establish a three-dimensional lattice Boltzmann model based on nucleation probability theory. The model was used to carry out numerical research on frost layer formation and growth process on cold wall surface. The model could not only simulate the gradual densification and thickening process of frost layer growth from the macro scale, but also describe the change process of the frost layer structure caused by ice branch growth on the micro scale. The average thickness, average density and the amount of the frost layer could be obtained. Through this model, the temporal and spatial evolution characteristics of the topography of the frost layer were obtained. The model was used to analyze the effects of cold wall surface temperature, relative humidity and cold surface wettability on the frosting characteristics. The average thickness, frost average density, frost quality and average solid volume fraction of frost at different times were obtained by calculation. 展开更多
关键词 lattice BOLTZMANN MODEL IMPROVED ENTHALPY MODEL nucleation probability MODEL three-dimensional frost surface WETTABILITY
基于土地集约利用的长株潭城市群建设用地供需仿真模拟(英文)
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作者 熊鹰 陈云 +2 位作者 彭芬 李静芝 阎晓静 《地理学报:英文版》 SCIE CSCD 2019年第8期1346-1362,共17页
Urban land intensive use is an important indicator in harmonizing the relationship between land supply and demand. The system dynamics(SD) can be used to construct the feedback loop between urban construction land sup... Urban land intensive use is an important indicator in harmonizing the relationship between land supply and demand. The system dynamics(SD) can be used to construct the feedback loop between urban construction land supply and demand and index variable function. Based on this, this study built a supply and demand system dynamic model of urban construction land for Chang-Zhu-Tan urban agglomeration. This model can simulate the change trends of supply and demand of construction land, industrial land, and residential land in 2016–2030 by three scenarios of low, medium, and high intensity modes. The results showed that the scale of construction land of urban agglomeration is expanding, with a rapid increase rate for the urban construction land. The scale and speed of land use based on the three intensity modes existed differences. The large scale and supply of construction land in the low intensity mode caused easily the waste of land resources. In high intensity mode, the scale and supply of construction land were reduced against the healthy development of new-type urbanization. In the medium intensity mode, the scale and supply of land use adapted to the socio-economic development and at the same time reflected the concept of modern urban development. In addition, the results of this study found that the proportion of industrial land in construction land ranged from 15% to 21%, which increased year by year in the low intensity mode, and decreased slowly and stabilized in medium and high intensity modes. The proportion of residential land in construction land ranged from 27% to 35%, which decreased in the low and the medium intensity modes, and maintained a high level in the higher intensity mode. This study contributes to provide scientific reference for decision-making optimization of land supply and demand, urban planning, and land supply-side reform. 展开更多
关键词 intensive URBAN LAND use LAND supply and demand simulation MODEL system dynamic MODEL CHANG-ZHU-TAN URBAN AGGLOMERATION
Influence of Sino-US Agricultural Trade on China’s Total Agricultural Output Value Based on Cointegration Model 预览
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作者 Zhiyao LI 《亚洲农业研究:英文版》 2019年第5期7-10,共4页
According to the data of the total trade of agricultural products between China and the United States from 2009 to 2018 and the general description of agriculture in China,this paper adopts the method of econometric m... According to the data of the total trade of agricultural products between China and the United States from 2009 to 2018 and the general description of agriculture in China,this paper adopts the method of econometric model to make a detailed analysis of the agricultural trade between China and the United States by using cointegration analysis,Granger causality test and error correction model in order to explore the impact of agricultural trade between China and the United States on China’s agricultural development. The results of empirical analysis show that there is a balanced relationship between the trade of agricultural products between China and the United States and the development of agriculture in China. The total trade of agricultural products between China and the United States affects the development of China’s agriculture.In addition,in the short term,if the short-term fluctuation deviates from the long-term equilibrium,then the error correction term will reverse it with strength of 0. 378,so that the non-equilibrium state will gradually return to the equilibrium state. 展开更多
关键词 TRADE of agricultural products between China and the UNITED STATES Econometric MODEL CO-INTEGRATION analysis Error CORRECTION MODEL
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Assessment of Arctic sea ice simulations in CMIP5 models using a synthetical skill scoring method 预览
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作者 Liping Wu Xiao-Yi Yang Jianyu Hu 《海洋学报:英文版》 SCIE CAS CSCD 2019年第9期48-58,共11页
The Arctic sea ice cover has declined at an unprecedented pace since the late 20th century. As a result, the feedback of sea ice anomalies for atmospheric circulation has been increasingly evidenced. While climatic mo... The Arctic sea ice cover has declined at an unprecedented pace since the late 20th century. As a result, the feedback of sea ice anomalies for atmospheric circulation has been increasingly evidenced. While climatic models almost consistently reproduced a decreasing trend of sea ice cover, the reported results show a large distribution. To evaluate the performance of models for simulating Arctic sea ice cover and its potential role in climate change, this study constructed a reasonable metric by synthesizing both linear trends and anomalies of sea ice. This study particularly focused on the Barents Sea and the Kara Sea, where sea ice anomalies have the highest potential to affect the atmosphere. The investigated models can be grouped into three categories according to their normalized skill scores. The strong contrast among the multi-model ensemble means of different groups demonstrates the robustness and rationality of this method. Potential factors that account for the different performances of climate models are further explored. The results show that model performance depends more on the ozone datasets that are prescribed by the model rather than on the chemical representation of ozone. 展开更多
关键词 ARCTIC sea ice CLIMATE model Barents and Kara SEAS MULTI-MODEL ENSEMBLE mean
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Comparative Analysis of Fractional Vegetation Cover Estimation Based on Multi-sensor Data in a Semi-arid Sandy Area 预览
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作者 LIU Qiuyu ZHANG Tinglong +3 位作者 LI Yizhe LI Ying BU Chongfeng ZHANG Qingfeng 《中国地理科学:英文版》 SCIE CSCD 2019年第1期166-180,共15页
The estimation of fractional vegetation cover(FVC) is important for identifying and monitoring desertification, especially in arid and semiarid regions. By using regression and pixel dichotomy models, we present the c... The estimation of fractional vegetation cover(FVC) is important for identifying and monitoring desertification, especially in arid and semiarid regions. By using regression and pixel dichotomy models, we present the comparison of Sentinel-2A(S2) multispectral instrument(MSI) and Landsat 8(L8) operational land imager(OLI) data regarding the retrieval of FVC in a semi-arid sandy area(Mu Us Sandland, China, in August 2016). A combination of unmanned aerial vehicle(UAV) high-spatial-resolution images and field plots were used to produce verified data. Based on a normalized difference vegetation index(NDVI) regression model, the results showed that, compared with that of L8, the coefficient of determination(R2) of S2 increased by 26.0%, and the root mean square error(RMSE) and the sum of absolute error(SAE) decreased by 3.0% and 11.4%, respectively. For the ratio vegetation index(RVI) regression model, compared with that of L8, the R2 of S2 increased by 26.0%, and the RMSE and SAE decreased by 8.0% and 20.0%, respectively. When the pixel dichotomy model was used, compared with that of L8, the RMSE of S2 decreased by 21.3%, and the SAE decreased by 26.9%. Overall, S2 performed better than L8 in terms of FVC inversion. Additionally, in this paper, we develop a verified scheme based on UAV data in combination with the object-based classification method. This scheme is feasible and sufficiently robust for building relationships between field data and inversion results from satellite data. Further, the synergy of multi-source sensors(especially UAVs and satellites) is a potential effective way to estimate and evaluate regional ecological environmental parameters(FVC). 展开更多
关键词 fractional vegetation cover (FVC) Sentinel-2A (S2) unmanned AERIAL vehicle (UAV)image PIXEL DICHOTOMY MODEL regression MODEL
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CFD simulation of tidal current farm by using AL model 预览
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作者 Cheng Liu Changhong Hu 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第1期34-40,共7页
In this study,an efficient numerical method for predicting the wake interference of multiple turbines is presented.The actuator line (AL) model instead of the geometry-resolved method is adopted to represent the rotor... In this study,an efficient numerical method for predicting the wake interference of multiple turbines is presented.The actuator line (AL) model instead of the geometry-resolved method is adopted to represent the rotor.The large-eddy simulation (LES) is performed to predict wakes of multiple turbines operated in turbulent flows.An efficient immersed boundary (IB) method with moving least square reconstruction (MLS) is developed to model the nacelle and support structure of the tidal turbine.A simple wall function based on the MLS-IB method and boundary-layer equations is employed to compute the instantaneous wall shear stress.Laminar flow simulations of unsteady flows past a cylinder illustrate the accuracy of the wall function IB method.Finally,the proposed method is extended to study turbulent flow past tandem tidal rotors,in which the wake profile behind rotors is analyzed.The results are found to be in reasonable agreement with published data. 展开更多
关键词 TIDAL current FARM immersed BOUNDARY method wall fimction MODEL large EDDY simulation (LES) ACTUATOR line MODEL
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爆燃压裂起裂模型常见问题分析与修正 预览
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作者 孙林 黄波 熊培祺 《中国海上油气》 CAS CSCD 北大核心 2019年第1期133-138,共6页
目前爆燃压裂起裂常用模型单位不统一、物理意义模糊、模拟功能范围窄,导致模型无法正常计算或者有关参数无法求解。通过公式单位推导与物理意义分析,对爆燃压裂峰值压力简易模型、挤入液体模型中的单位不统一问题和压力与时间主模型、... 目前爆燃压裂起裂常用模型单位不统一、物理意义模糊、模拟功能范围窄,导致模型无法正常计算或者有关参数无法求解。通过公式单位推导与物理意义分析,对爆燃压裂峰值压力简易模型、挤入液体模型中的单位不统一问题和压力与时间主模型、挤入液体模型、挤入气体模型和裂缝与时间关系模型物理意义模糊问题进行了修正;同时根据牛顿第二定律和材料力学方程,按照压力波在液柱中的传递过程进行推导建立了应用范围更广的压挡液运动新模型。现场应用结果表明,压挡液运动新模型具有较高的计算精度,模拟计算结果与现场测试数据吻合较好,可为爆燃压裂参数预测和安全控制提供参考。 展开更多
关键词 爆燃压裂 模型 问题修正 压挡液运动新模型
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Projection of Landslides in China during the 21st Century under the RCP8.5 Scenario
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作者 Shuangshuang HE Jun WANG Huijun WANG 《气象学报:英文版》 SCIE CSCD 2019年第1期138-148,共11页
More and more rainstorms and other extreme weather events occur in the context of global warming, which may increase the risks of landslides. In this paper, changes of landslides in the 21 st century of China under th... More and more rainstorms and other extreme weather events occur in the context of global warming, which may increase the risks of landslides. In this paper, changes of landslides in the 21 st century of China under the high emission scenario RCP8.5(Representative Concentration Pathway) are projected by using a statistical landslide forecasting model and the regional climate model RegCM4.0. The statistical landslide model is based on an improved landslide susceptibility map of China and a rainfall intensity–duration threshold. First, it is driven by observed rainfall and RegCM4.0 rainfall in 1980–99, and it can reproduce the spatial distribution of landslides in China pretty well.Then, it is used to forecast the landslide changes over China in the future under the RCP8.5 scenario. The results consistently reveal that landslides will increase significantly in most areas of China, especially in the southeastern, northeastern, and western parts of Northwest China. The change pattern at the end of the 21 st century is generally consistent with that in the middle of the 21 st century, but with larger increment and magnitude. In terms of the probability,the proportion of grid points that are very likely and extremely likely to experience landslides will also increase. 展开更多
关键词 LANDSLIDES PROJECTION STATISTICAL LANDSLIDE forecasting MODEL regional climate MODEL
Physical and coupled fully three-dimensional numerical modeling ofpressurized bottom outlet ushing processes in reservoirs 预览
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作者 Ousmane Sawadogo Gerrit R. Basson Simon Schneiderbauer 《国际泥沙研究:英文版》 SCIE 2019年第5期461-474,共14页
Sediment deposition in reservoirs is an important research topic in engineering practice. Reservoir sedimentation has the potential to affect ood levels, drainage for agricultural land, pump station and hydropower ope... Sediment deposition in reservoirs is an important research topic in engineering practice. Reservoir sedimentation has the potential to affect ood levels, drainage for agricultural land, pump station and hydropower operation as well as navigation. This paper describes the development of a coupled fully three-dimensional (3D) numerical model for the prediction of the local sediment ushing scour upstream of the bottom outlet. The presented numerical model solves the Navier-Stokes equations in conjunction with the k- turbulence model which includes both sediment transport and hydrodynamic parameters. The proposed coupled fully 3D numerical model is used to simulate experimental tests based on non-cohesive sediment. The geometric features of the scour hole (temporal and spatial hole devel- opment) upstream of the bottom outlet were reasonably well predicted compared to the experimental data. Furthermore, the velocity eld upstream of the bottom outlet was in good agreement with mea- surements. The proposed numerical model for bottom outlet ushing was, therefore, validated because of its ability to accurately predict the scour hole development during the ushing process. The proposed numerical model can be considered reliable provided that the model is correctly calibrated and set up to re ect the conditions of a particular case study. 展开更多
关键词 Bottom OUTLET COUPLED flow/sediment MODEL SEDIMENT FLUSHING 3D numerical MODEL Packed bed Reservoir
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Evaluation of SWAT Model performance on glaciated and non-glaciated subbasins of Nam Co Lake, Southern Tibetan Plateau, China
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作者 Muhammad ADNAN KANG Shi-chang +3 位作者 ZHANG Guo-shuai Muhammad Naveed ANJUM Muhammad ZAMAN ZHANG Yu-qing 《山地科学学报:英文版》 SCIE CSCD 2019年第5期1075-1097,共23页
This paper presents an assessment of the Soil and Water Assessment Tool(SWAT) on a glaciated(Qugaqie) and a non-glaciated(Niyaqu) subbasin of the Nam Co Lake. The Nam Co Lake is located in the southern Tibetan Plateau... This paper presents an assessment of the Soil and Water Assessment Tool(SWAT) on a glaciated(Qugaqie) and a non-glaciated(Niyaqu) subbasin of the Nam Co Lake. The Nam Co Lake is located in the southern Tibetan Plateau, two subbasins having catchment areas of 59 km~2 and 388 km~2, respectively. The scores of examined evaluation indices(i.e., R~2, NSE, and PBIAS) established that the performance of the SWAT model was better on the monthly scale compared to the daily scale. The respective monthly values of R~2, NSE, and PBIAS were 0.94, 0.97, and 0.50 for the calibration period while 0.92, 0.88, and -8.80 for the validation period. Glacier melt contribution in the study domain was simulated by using the SWAT model in conjunction with the Degree Day Melt(DDM) approach. The conjunction of DDM with the SWAT Model ensued improved results during both calibration(R~2=0.96, NSE=0.95, and PBIAS=-13.49) and validation (R~2=0.97, NSE=0.96, and PBIAS=-2.87) periods on the monthly time scale. Average contribution(in percentage) of water balance components to the total streamflow of Niyaqu and Qugaqie subbasins was evaluated. We found that the major portion(99.45%) of the streamflow in the Niyaqu subbasin was generated by snowmelt or rainfall surface runoff(SURF_Q), followed by groundwater(GW_Q, 0.47%), and lateral(LAT_Q, 0.06%) flows. Conversely, in the Qugaqie subbasin, major contributor to the streamflow(79.63%) was glacier melt(GLC_Q), followed by SURF_Q(20.14%), GW_Q(0.13%), and LAT_Q(0.089%). The contribution of GLC_Q was the highest(86.79%) in July and lowest(69.95%) in September. This study concludes that the performance of the SWAT model in glaciated catchment is weak without considering glacier component in modeling;however, it performs reasonably well in non-glaciated catchment. Furthermore, the temperature index approach with elevation bands is viable in those catchments where streamflows are driven by snowmelt. Therefore, it is recommended to use the SWAT Model in conjunction with DDM or energy base model to simulat 展开更多
关键词 SWAT MODEL NAM Co Lake DEGREE-DAY MELT MODEL Streamflow HYDROLOGICAL Response Unit
A Flexible Multi-Layer Map Model Designed for Lane-Level Route Planning in Autonomous Vehicles 预览
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作者 Kun Jiang Diange Yang +2 位作者 Chaoran Liu Tao Zhang Zhongyang Xiao 《工程(英文)》 2019年第2期305-318,共14页
An increasing number of drivers are relying on digital map navigation systems in vehicles or mobile phones to select optimal driving routes in order to save time and improve safety. In the near future, digital map nav... An increasing number of drivers are relying on digital map navigation systems in vehicles or mobile phones to select optimal driving routes in order to save time and improve safety. In the near future, digital map navigation systems are expected to play more important roles in transportation systems. In order to extend current navigation systems to more applications, two fundamental problems must be resolved: the lane-level map model and lane-level route planning. This study proposes solutions to both problems. The current limitation of the lane-level map model is not its accuracy but its flexibility;this study proposes a novel seven-layer map structure, called as Tsinghua map model, which is able to support autonomous driving in a flexible and efficient way. For lane-level route planning, we propose a hierarchical route-searching algorithm to accelerate the planning process, even in the presence of complicated lane networks. In addition, we model the travel costs allocated for lane-level road networks by analyzing vehicle maneuvers in traversing lanes, changing lanes, and turning at intersections. Tests were performed on both a grid network and a real lane-level road network to demonstrate the validity and efficiency of the proposed algorithm. 展开更多
关键词 Lane-level ROUTE planning Tsinghua map MODEL TRAVEL cost MODEL
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Resilient PNT Concept Frame 预览
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作者 Yuanxi YANG 《测绘学报(英文版)》 2019年第3期1-7,共7页
The concept of resilient positioning, navigation and timing (PNT) is described. The definition of resilient PNT is given, the relationship between integrated (or comprehensive) PNT and resilient PNT is analyzed, and i... The concept of resilient positioning, navigation and timing (PNT) is described. The definition of resilient PNT is given, the relationship between integrated (or comprehensive) PNT and resilient PNT is analyzed, and it is pointed out that the integrated PNT is the foundation of resilient PNT. Resilient PNT should be divided into resilient sensor integration, resilient functional model and resilient stochastic model. The strategy and principles of resilient integration of sensors are discussed. The resilient integration of sensors should be designed following the optimal, available, compatible and interoperable principles. The concepts of resilient functional model and possible modification strategies of the different functional models are also described. Several possible optimal routes for resilient stochastic model improvements are also set forth. It is pointed out that the optimal improvements of stochastic models for multi PNT sources should follow the same variance scale. At last, the resilient PNT data fusion for state parameters are given based on the resilient functional and stochastic models. 展开更多
关键词 resilient positioning NAVIGATION and TIMING (PNT) integrated PNT micro PNT resilient functional MODEL resilient stochastic MODEL
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