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Improving the Accuracy of Vegetation Index Retrieval for Biomass by Combining Ground-UAV Hyperspectral Data-A New Method for Inner Mongolia Typical Grasslands
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作者 Ruochen Wang Jianjun Dong +3 位作者 Lishan Jin Yuyan Sun Taogetao Baoyin Xiumei Wang 《Phyton-International Journal of Experimental Botany》 SCIE 2024年第2期387-411,共25页
Grassland biomass is an important parameter of grassland ecosystems.The complexity of the grassland canopy vegetation spectrum makes the long-term assessment of grassland growth a challenge.Few studies have explored t... Grassland biomass is an important parameter of grassland ecosystems.The complexity of the grassland canopy vegetation spectrum makes the long-term assessment of grassland growth a challenge.Few studies have explored the original spectral information of typical grasslands in Inner Mongolia and examined the influence of spectral information on aboveground biomass(AGB)estimation.In order to improve the accuracy of vegetation index inversion of grassland AGB,this study combined ground and Unmanned Aerial Vehicle(UAV)remote sensing technology and screened sensitive bands through ground hyperspectral data transformation and correlation analysis.The narrow band vegetation indices were calculated,and ground and airborne hyperspectral inversion models were established.Finally,the accuracy of the model was verified.The results showed that:(1)The vegetation indices constructed based on the ASD FieldSpec 4 and the UAV were significantly correlated with the dry and fresh weight of AGB.(2)The comparison between measured R^(2) with the prediction R^(2) indicated that the accuracy of the model was the best when using the Soil-Adjusted Vegetation Index(SAVI)as the independent variable in the analysis of AGB(fresh weight/dry weight)and four narrow-band vegetation indices.The SAVI vegetation index showed better applicability for biomass monitoring in typical grassland areas of Inner Mongolia.(3)The obtained ground and airborne hyperspectral data with the optimal vegetation index suggested that the dry weight of AGB has the best fitting effect with airborne hyperspectral data,where y=17.962e^(4.672x),the fitting R^(2) was 0.542,the prediction R^(2)was 0.424,and RMSE and REE were 57.03 and 0.65,respectively.Therefore,established vegetation indices by screening sensitive bands through hyperspectral feature analysis can significantly improve the inversion accuracy of typical grassland biomass in Inner Mongolia.Compared with ground monitoring,airborne hyperspectral monitoring better reflects the inversion of actual surface biomass.It provides a reliable modeling framework for grassland AGB monitoring and scientific and technological support for grazing management. 展开更多
关键词 Aboveground biomass inversion model vegetation index unmanned aerial vehicle typical grassland
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Analysis of a Typical Case of Meteorological Service in Tangpu Reservoir
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作者 Quan SHAN Yuxin DING +2 位作者 Tingting GU Jinxin WANG Kai TANG 《Meteorological and Environmental Research》 2024年第2期44-47,共4页
The continuous rainy precipitation process from February to March in 2019 was selected to analyze the effect of meteorological service in Tangpu Reservoir basin,so as to sum up service experience and then lay a better... The continuous rainy precipitation process from February to March in 2019 was selected to analyze the effect of meteorological service in Tangpu Reservoir basin,so as to sum up service experience and then lay a better foundation for subsequent services.In response to the rainy weather from December 2018 to early 2019,three rounds of flood discharge were carried out in Tangpu Reservoir.During February-March in 2019,the hit rate of short-term area rainfall forecast for Tangpu Reservoir was 80.0%.Compared with the median of forecast interval,the average absolute error was 7.6 mm,and the relative error was 32.7%.The large deviation in the forecast from March 27 to 28 was deeply analyzed,and it is found that the main reasons were excessive reliance on and trust in a single model,insufficient correction of the actual situation,and insufficient judgment of the nature of precipitation.For the future reservoir meteorological service,three aspects of thinking were put forward,such as further strengthening the sharing of hydrological and meteorological information,improving the forecasting ability,and deepening the research of runoff forecast models. 展开更多
关键词 Tangpu Reservoir Meteorological service Continuous rain Analysis of a typical case
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Analysis on Typical Spatio-temporal Characteristics of Open-cast Mining and Its Countermeasures
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作者 Qingyou AO Qiang FU +2 位作者 Zhihua LIU Yu XUN Lin LIN 《Asian Agricultural Research》 2024年第5期20-24,共5页
In order to deal with the special spatio-temporal environmental changes encountered in the process of open-cast mining,taking Huolinhe No.1 Open-cast Mine as the research object,this paper studied its typical problems... In order to deal with the special spatio-temporal environmental changes encountered in the process of open-cast mining,taking Huolinhe No.1 Open-cast Mine as the research object,this paper studied its typical problems in river reconstruction and cultural relics protection.The study focused on eight key core aspects,including the design optimization of the spatial layout of the mining area,the accurate estimation of the mineral resources reserves,the scientific theoretical demonstration of the mining scale,the fine analysis and calculation of the stripping ratio,the comprehensive consideration of the transport distance and efficiency,the accurate judgment of the best time for the implementation of the transformation,the analysis and evaluation of the slope stability,and the overall planning of the production system.The results show that the extracted problem-solving strategies and scheme system for special mining conditions can not only provide specific and practical guidance for Huolinhe No.1 Open-cast Mine,but also serve as a valuable reference and practical reference for other open-cast mine enterprises facing similar challenges. 展开更多
关键词 Open-cast mining in the mining area typical space-time environment River reconstruction Cultural relics protection Spatial layout
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Rare and lacking typical clinical symptoms of liver tumors:Four case reports
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作者 Yun Zhao Yu-Kun Bie +2 位作者 Guang-Ya Zhang Yi-Bin Feng Feng Wang 《World Journal of Gastrointestinal Oncology》 SCIE 2024年第10期4264-4273,共10页
BACKGROUND Rare liver tumors(RLTs)have an extremely low likelihood of forming,and some have been recorded only in isolated cases.The lack of normal clinical symptoms in RLTs makes preoperative diagnosis extremely chal... BACKGROUND Rare liver tumors(RLTs)have an extremely low likelihood of forming,and some have been recorded only in isolated cases.The lack of normal clinical symptoms in RLTs makes preoperative diagnosis extremely challenging,which results in frequent misinterpretation.The present case report helps enhance our ability to recognize and treat uncommon liver tumor disorders.CASE SUMMARY We describe four distinct examples of rare liver tumor diseases.These cases were all true cases with no conventional clinical signs or imaging findings.In all patients,hepatic occupancy was discovered on physical examination,which raised the preoperative suspicion of hepatic cancer.All tumors were surgically removed,and postoperative histology and immunohistochemistry were performed to confirm the diagnosis.The first patient had primary hepatic fibrosarcoma.The second case involved a primary hepatic neuroendocrine tumors.These two patients had malignant liver tumors,and both had extremely satisfactory surgical outcomes.The third case involved focal hepatic steatosis,and the fourth case involved a single necrotic nodule in the liver.These two patients had benign liver tumors,but they had already undergone surgery and did not require any postoperative care.CONCLUSION The number of patients with RLTs is small,and the clinical and imaging results are vague.Preoperative diagnosis is challenging,and patients are sometimes mistakenly diagnosed with liver cancer,which leads to unnecessary surgical therapy in certain individuals. 展开更多
关键词 Liver tumor Primary hepatic fibrosarcoma Primary hepatic neuroendocrine tumor Focal hepatic steatosis Solitary necrotic nodule of the liver Lack of typical clinical symptoms Case report
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Trade-off and Synergy of Rural Functions Under County Depopulation in the Typical Black Soil Region of Northeast China 被引量:2
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作者 LI Dongmei WEN Qing +1 位作者 QI Yue ZHANG Pingyu 《Chinese Geographical Science》 SCIE CSCD 2023年第4期616-633,共18页
As the population continues to shrink in the black soil region of Northeast China since 2000,it is critical to master the impact of population shrinkage on rural functions to realize rural revitalization and sustainab... As the population continues to shrink in the black soil region of Northeast China since 2000,it is critical to master the impact of population shrinkage on rural functions to realize rural revitalization and sustainable development.In this study,we focused on the impacts of depopulation on the evolution and interrelationship of rural subfunctions.Based on the rural function indexes system,the TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution)method,spatial analysis method,and mathematical statistics analysis method were used to summarize the spatial and temporal characteristics of rural function development,as well as the effect of population shrinkage in the typical black soil region of Northeast China.The results showed that depopulation varied in the extent and duration between the forested region and plain areas,which both impacted the trajectories of rural subfunctions evolution.For the economic development function and ecological conservation function,the effect of continuous slight depopulation was beneficial,while the effect of rapid depopulation was adverse,which was exactly opposite to the agricultural production function.All forms of population shrinkage were conducive to the development of the social security function.With the deepening population shrinkage,depopulation mainly promoted the collaborative development between subfunctions in this study,except the relationship between agricultural production and social security function.But effects of depopulation on the interrelationship of rural subfunctions varied between the forested region and plain areas in some cases.The results provided evidence for the cognition that population shrinkage had complicated effects on rural subfunctions. 展开更多
关键词 rural function depopulation trade-off and synergy typical black soil region Northeast China
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A case of atypical neurological symptoms and high cerebro-spinal fluid acetone level due to transdermal exposure to isopropanol
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作者 Côme Fruit Sophie Guillotin +5 位作者 Marie Wolfrum Thomas Lanot Florent Battefort Pierre Girardie Marie Rafiq Nicolas Delcourt 《World Journal of Emergency Medicine》 SCIE CAS CSCD 2023年第2期152-154,共3页
Dear editor, Isopropanol, also named 2-propanol or isopropyl alcohol(IPA), is a colorless, volatile liquid found in numerous household chemicals, such as cleaners and disinfectants, which typically contain a 70% solut... Dear editor, Isopropanol, also named 2-propanol or isopropyl alcohol(IPA), is a colorless, volatile liquid found in numerous household chemicals, such as cleaners and disinfectants, which typically contain a 70% solution of IPA in water. IPA is also extensively used in industry and laboratories as a solvent. 展开更多
关键词 ACETONE typically ALCOHOL
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Automatic Extraction of Typical River Vegetation Elements Based on Low-altitude Remote Sensing Images
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作者 Xiaomeng ZHANG Hao WU 《Meteorological and Environmental Research》 CAS 2023年第1期70-75,共6页
Based on low-altitude remote sensing images,this paper established sample set of typical river vegetation elements and proposed river vegetation extraction technical solution to adaptively extract typical vegetation e... Based on low-altitude remote sensing images,this paper established sample set of typical river vegetation elements and proposed river vegetation extraction technical solution to adaptively extract typical vegetation elements of river basins.The main research of this paper were as follows:(1)a typical vegetation extraction sample set based on low-altitude remote sensing images was established.(2)A low-altitude remote sensing image vegetation extraction model based on the focus perception module was designed to realize the end-to-end automatic extraction of different types of vegetation areas of low-altitude remote sensing images to fully learn the spectral spatial texture information and deep semantic information of the images.(3)By comparison with the baseline method,baseline method with embedded focus perception module showed an improvement in the precision by 7.37%and mIoU by 49.49%.Through visual interpretation and quantitative calculation analysis,the typical river vegetation adaptive extraction network has effectiveness and generalization ability,consistent with the needs of practical applications of vegetation extraction. 展开更多
关键词 altitude remote sensing images Deep learning Semantic segmentation typical river vegetation extraction Attention
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Detecting Vegetation Fractional Coverage of Typical Steppe in Northern China Based on Multi-scale Remotely Sensed Data 被引量:15
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作者 李晓兵 陈云浩 +1 位作者 史培军 陈晋 《Acta Botanica Sinica》 CSCD 2003年第10期1146-1156,共11页
One of the study objectives of global change is land use/cover change (LUCC) by using multiscale remotely sensed data on global and regional scale. In this paper, field sample, digital camera, Landsat-ETM+ (ETM+, Enha... One of the study objectives of global change is land use/cover change (LUCC) by using multiscale remotely sensed data on global and regional scale. In this paper, field sample, digital camera, Landsat-ETM+ (ETM+, Enhanced Thematic Mapper) image and the National Oceanic and Atmospheric Administration/the advanced very high resolution radiometer (NOAA/AVHRR) image were integrated to detect, simulate and analyze the vegetation fractional coverage of typical steppe in northern China. The results show: (1) Vegetation fractional coverage measured by digital camera is more precise than results measured by other methods. It can be used to validate other measuring results. (2) Vegetation fractional coverage measured by 1 m 2 field sample change fluctuantly for different observers and for different sample areas. In this experiment, the coverage is generally high compared with the result measured by digital camera, and the average absolute error is 9.92%, but two groups measure results, correlation coefficient r(2) = 0.89. (3) Three kinds of methods using remotely sensed data were adopted to simulate the vegetation fractional coverage. Average absolute errors of the vegetation fractional coverage, measured by ETM+ and NOAA, are respectively 7.03% and 7.83% compared with the result measured by digital camera. When NOAA pixel was decomposed by ETM+ pixels after geometrical registry, the average absolute errors measured by this method is 5.68% compared with the digital camera result. Correction coefficients of three results with digital camera result r(2) are respectively 0.78, 0.61 and 0.76. (4) The result of statistic model established by NOAA-NDVI (NDVI, Normalized Difference Vegetation Index) and the vegetation fractional coverage measured by digital camera show lower precision (r(2) = 0.65) than the result of statistic model established by ETM+-NDVI and digital camera coverage then converted to NOAA image (r(2) = 0.80). Pixel decomposability method improves the precision of measuring the vegetation fractional coverage on a large scale. This is a significant practice on scaling by using remotely sensed data. Integrated application of multi-scale remotely sensed data in earth observation will be an important approach to promoting measuring precision of ecological parameters. 展开更多
关键词 multi-scale remote sensing typical steppe vegetation fractional coverage
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Interactions between Vegetation and Climatic Factors in Typical Arid and Humid Regions of China Based on NDVI 被引量:1
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作者 李洪利 孙善磊 +3 位作者 孙杰 黄珏 顾人颖 骆杨 《Meteorological and Environmental Research》 CAS 2010年第2期48-52,56,共6页
According to the distribution of arid and humid regions in China,the typical arid region (Erjina),the typical semi-arid/semi-humid region (Guanzhong basin/Loess Plateau) and the typical humid region (Poyang Lake basin... According to the distribution of arid and humid regions in China,the typical arid region (Erjina),the typical semi-arid/semi-humid region (Guanzhong basin/Loess Plateau) and the typical humid region (Poyang Lake basin) were selected as the study areas.Based on NDVI data from 1982 to 2000 and meteorological observing data of three study areas from 1981 to 2000,the interactions between vegetation NDVI and climatic factors (temperature and precipitation) in typical arid and humid regions were discussed in this study.The results showed that in the responses of vegetation to climatic factors,vegetation in the typical arid region (Erjina) was more sensitive to precipitation,while vegetation in the typical semi-arid/semi-humid region (Guanzhong basin/Loess Plateau) was more sensitive to both temperature and precipitation,and vegetation in the typical humid region (Poyang Lake basin) was more sensitive to temperature.As for effects of vegetation on climatic factors,there was a remarkable negative correlation between vegetation NDVI in the past winter and temperature in the present summer,and also a significant positive correlation between vegetation NDVI in the past winter and precipitation in the present summer.However,in the typical semi-arid/semi-humid region (Guanzhong basin/Loess Plateau),there was a significant positive correlation between vegetation NDVI in the present spring and temperature in the present summer. 展开更多
关键词 typical arid and humid region NDVI Climatic factor Temperature PRECIPITATION China
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Dynamic of Chinas cultivated land and landcover changes of its typical regions based on remote sensing data 被引量:1
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作者 张佳华 董文杰 +2 位作者 王长耀 刘纪远 姚凤梅 《Journal of Forestry Research》 SCIE CAS CSCD 2001年第3期183-186,210,共5页
Using the multi-temporal Landsat data and survey data of national resources, the authors studied the dynamics of cultivated land and landcover changes of typical ecological regions in China. The results of investigati... Using the multi-temporal Landsat data and survey data of national resources, the authors studied the dynamics of cultivated land and landcover changes of typical ecological regions in China. The results of investigation showed that the whole distribution of the cultivated land shifted to Northeast and Northwest China, and as a result, the ecological quality of cultivated land dropped down. The seacoast and cultivated land in the area of Yellow River Mouth expanded by an increasing rate of 0.73 kma-1, with a depositing rate of 2.1 kma-1. The desertification area of the dynamic of Horqin Sandy Land increased from 60.02% of the total land area in1970s to 64.82% in1980s but decreased to 54.90% in early 1990s. As to the change of North Tibet lakes, the water area of the Namu Lake decreased by 38.58 km2 from year 1970 to 1988, with a decreasing rate of 2.14 km2a-1. 展开更多
关键词 Remote sensing data Cultivated land Landcover change typical ecological regions China
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Soil structure characters of different soil and water conservation plantations in typical black soil region 被引量:1
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作者 史长婷 王恩姮 +1 位作者 谷会岩 陈祥伟 《Journal of Forestry Research》 SCIE CAS CSCD 2010年第2期151-154,I0004,共5页
A study was conducted to determine the characters of soil structure in different water and soil conservation forests in Keshan County,northwest of Heilongjiang Province,China.The soil bulk density,the ratio of non-cap... A study was conducted to determine the characters of soil structure in different water and soil conservation forests in Keshan County,northwest of Heilongjiang Province,China.The soil bulk density,the ratio of non-capillary porosity and capillary porosity(NCP/CP),and the generalized soil structure index(GSSI) were measured for Fraxinus mandshurica,Larix gmelini,Pinus sylvestris var.mongolica,and Picea koraiensis plantations as well as the abandoned land(as control) adjacent to the forests in typical black soil region.Results show that at soil depth of 0–30cm,the soil bulk density of F.mandshurica forest and L.gmelini forest was lower than that of P.sylvestris var.mongolica forest and P.koraiensis forest,with the relative decrease of 8.04%–11.01%.The soil bulk density of L.gmelini forest was significantly different from that of the P.sylvestris var.mongolica forest and P.koraiensis forest.The NCP/CP values of the four types of plantations were all higher(59.75%–128.82% relatively) than that of abandoned land(p〈0.05),indicating that the soil aeration and permeability under forest were enhanced,especially under L.gmelini forest.GSSI values of the four types of forests were also relatively higher(2.98%–4.36%) than abandoned land(p〈0.05),indicating that those soil and water conservation forests,especially the F.mandshurica forest and P.koraiensis forest,can promote soil condition to approximate ideal soil structure.The result of this study can provide theoretical basis for scientifically evaluating the effects of vegetation restoration on soil quality in typical black soil region. 展开更多
关键词 typical black soil soil and water conservation plantation Bulk density GSSI NCP/CP
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Effect of Irrigation on Groundwater Dynamic Change in the Typical Irrigated Area of Qinghai Province 被引量:2
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作者 周鸿文 吕文星 +2 位作者 唐红波 王永峰 申国峰 《Agricultural Science & Technology》 CAS 2016年第7期1718-1722,共5页
Under the influence of the natural and human factors, water table of irri- gated area Changes frequently, but it is mainly affected by irrigation water infiltration replenishment during the irrigation. 5 groundwater o... Under the influence of the natural and human factors, water table of irri- gated area Changes frequently, but it is mainly affected by irrigation water infiltration replenishment during the irrigation. 5 groundwater observation wells were constructed in experimental plot of the Daxia irrigated area to carry out the experiment of the effect of irrigation on groundwater dynamic change in this research. The results showed that the groundwater stage dynarnic change rule of spring and seedling irri- gation stage in the typical plot was fit to the hydrological geology condition of grade- I terrace of Huangshui river valley. On the whole, lateral canal water direction formed a line effect. The No. 1 and No. 2 observation well were the closest to the lateral canal, which received more supplies, and the water level was the highest; the No, 3 observation well took the second place; The No. 4 and No. 5 observation well accepted least supplies, and the water level was the lowest. The rangeability of water table of spring irrigation period was significantly higher than that of seedling irrigation period, this is mainly due to the difference value of intake water volume and drainage water volume of spring irrigation phase was significantly higher than the seedling irrigation phase. 展开更多
关键词 Farm irrigation Water table Dynamiq Change typical irrigated area basin in Qinghai Province
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Research on Comparative Advantage and Typical Models of Circular Agriculture Economy in Eastern and Mid-China Region
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作者 周颖 周清波 甘寿文 《Agricultural Science & Technology》 CAS 2015年第11期2573-2580,共8页
Developing agricultural circular economy is the important measures of relieving the pressure on agricultural resources, preserving the ecological environment and promoting the sustainable development of agriculture an... Developing agricultural circular economy is the important measures of relieving the pressure on agricultural resources, preserving the ecological environment and promoting the sustainable development of agriculture and rural economy. Based on the idea of circulation of agricultural research as the breakthrough point, the research firstly detailed the concept and scientific connotation of circular egdculture in an all-round way and described and analyzed the advantages and conditions of the development of circular agriculture in eastern and middle regions of China from three aspects including resources endowment, conditions of economic development and industrial base conditions. Furthermore, the research analyzed the model char- actedstics and summarized the successful ex^dence to provide a reference for promoting the models with consideration of Taihu Lake Basin in South of Jiangsu, Yi- meng mountain areas in Southeast of Shandong and hills and mountains region in northwest Henan. Finally, the reseach put forward the development orientation of agricultural circular economy and countermeasures and suggestions to further enhance the level of development. 展开更多
关键词 Agricultural circular economy Comparative advantages typical model Mid-Eastem China
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The Construal of Typical Hypallage Under the Hybrid Model
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作者 张洁 《疯狂英语(理论版)》 2016年第3期192-194,共3页
In this paper,the hybrid model based on the conceptual blending theory and qualia structure is applied to the interpretation of the meaning construction of typical hypallage.Based on this study,it has been proved that... In this paper,the hybrid model based on the conceptual blending theory and qualia structure is applied to the interpretation of the meaning construction of typical hypallage.Based on this study,it has been proved that the hypallage is not only a creative and appealing linguistic phenomenon but also a productive cognitive operation based on the double scope integration which enable people to use the same modifier to describe the things which intuitively belong to distinct sort of types without any cognitive difficulties. 展开更多
关键词 typical hypallage conceptual blending theory qualia structure
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Sulfur cycle in the typical meadow Calamagrostis angustifolia wetland ecosystem in the Sanjiang Plain,Northeast China 被引量:9
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作者 LIU Jingshuang LI Xinhua 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2008年第4期470-475,共6页
The sulfur cycle and its compartmental distribution within an atmosphere-plant-soil system was studied using a compartment model in the typical meadow Calamagrostis angustifolia wetland in the Sanjiang Plain Northeast... The sulfur cycle and its compartmental distribution within an atmosphere-plant-soil system was studied using a compartment model in the typical meadow Calamagrostis angustifolia wetland in the Sanjiang Plain Northeast China. The results showed that in the typical meadow C. angustifolia wetland ecosystem, soil was the main storage compartment and current hinge of sulfur in which 98.4% sulfur was accumulated, while only 1.6% sulfur was accumulated in the plant compartment. In the plant subsystem, roots and litters were the main storage compartment of sulfur and they remained 83.5% of the total plant sulfur. The calculations of sulfur turnover through the compartments of the typical meadow C. angustifolia wetland ecosystem demonstrated that the above-ground component took up 0.99 gS/m^2 from the root, of which 0.16 gS/m^2 was translocated to the roots and 0.83 gS/m^2 to the litter. The roots took in 1.05 gS/m^2 from the soil, subsequent translocation back to the soil accounted for 1.31 gS/m^2, while there was 1.84 gS/m^2 in the litter and the net transfer of sulfur to the soil was more than 0.44 gS/(m^2·a). The emission of H2S from the typical meadow C. angustifolia wetland ecosystem to the atmosphere was 1.83 mgS/(m^2·a), while carbonyl sulfide (COS) was absorbed by the typical meadow C. angustifolia wetland ecosystem from the atmosphere at the rate of 1.76 mgS/(m^2·a). The input of sulfur by the rainfall to the ecosystem was 4.85 mgS/m^2 during the growing season. The difference between input and output was 4.78 mgS/m^2, which indicated that sulfur was accumulated in the ecosystem and may cause wetland acidify in the future. 展开更多
关键词 the Sanjiang Plain typical meadow Calamagrostis angustifolia wetland ECOSYSTEM sulfur cycle
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Groundwater quality and land use change in a typical karst agricultural region:a case study of Xiaojiang watershed,Yunnan 被引量:15
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作者 JIANG Yongjun YUAN Daoxian +3 位作者 XIE Shiyou LI Linli ZHANG Gui HE Raosheng 《Journal of Geographical Sciences》 SCIE CSCD 2006年第4期405-414,共10页
Taking the typical karst agricultural region, Xiaojiang watershed in Luxi of Yurman Province as a research unit, utilizing the groundwater quality data in 1982 and 2004, the aerial photos in 1982 and TM images in 2004... Taking the typical karst agricultural region, Xiaojiang watershed in Luxi of Yurman Province as a research unit, utilizing the groundwater quality data in 1982 and 2004, the aerial photos in 1982 and TM images in 2004, supported by the GIS, we probe into the law and the reason of its space-time change of the groundwater quality over the past 22 years in the paper. The results show: (1) There were obvious temporal and spatial changes of groundwater quality during the past 22 years. (2) Concentrations of NH4^+, SO4^2- , NO3, NO2^-, Cl^- and the pH value, total hardness, total alkalinity increased significantly, in which NH4^2-, NO3, and NO2^- of groundwater exceeded the drinking water standards as a result of non-point pollution caused by the expansion of cultivated land and mass use of the fertilizer and pesticide. (3) Oppositely, Ca^2+ and HCO3^- showed an obvious decline trend due to forest reduction and degradation and stony desertification. Meantime, there was a dynamic relation between the groundwater quality change and the land use change. 展开更多
关键词 groundwater quality space-time change land use change typical karst agricultural region GIS Xiaojiang watershed
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High Performance Concrete and Its Typical Mixes 被引量:3
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作者 Cai Yuebo , Kwan Kwokhung , Cheung Yaukai Chan Honchuen Senior Engineer, Material and Structure Department, Nanjing Hydraulic Research Institute, Nanjing 210024 P. H. Doctor, Department of Civil and Structural Engineering, University of Hong Kong Professor, Department of Civil and Structural Engineering, University of Hong Kong 《China Ocean Engineering》 SCIE EI 1995年第3期335-344,共10页
With the modern development of chemical and mineral admixtures, it is now possible to produce much higher performance concrete than before. Higher performance does not only mean higher strength, but also better durabi... With the modern development of chemical and mineral admixtures, it is now possible to produce much higher performance concrete than before. Higher performance does not only mean higher strength, but also better durability, lower risk of thermal cracking and higher dimensional stability etc. The three most effective admixtures for producing high performance concrete are superplastieizer, pulverized fuel ash and condensed silica fume. This paper outlines the properties of these materials and presents some practical guidelines for their usage. 展开更多
关键词 high performance concrete SUPERPLASTICIZER pulverized fuel ash condensed silica fume typical mixes
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An Improved Method for Generating Typical Meteorological Years Used in Building Energy Simulation in China 被引量:2
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作者 Qiu-Hua Tao Zheng-Rong Li +2 位作者 Fu-Jian Jiang Yuan Lu Ling-Zhou Hu 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2014年第1期17-24,共8页
The present study proposes an improved method for generating better typical meteorological years( TMYs) used in building energy simulation in China. Modifications are made to the commonly used Sandia method,by optimiz... The present study proposes an improved method for generating better typical meteorological years( TMYs) used in building energy simulation in China. Modifications are made to the commonly used Sandia method,by optimizing the weightings of indices and thus giving more emphasis to dry bulb temperature and relative humidity and less to wind velocity. After analyzing the solar heat gain on the vertical envelop,an index of diffuse radiation rather than direct normal radiation is added for solar radiation. Using the improved method proposed,TMYs for 5 representative cities of 5 major climate zones in China are generated from the meteorological data recorded during the period 1981—2010. The results show that,compared with previous studies,the monthly diffuse solar radiation of typical meteorological months generated by the improved method are the"closest"to the 30-year average,and the comparison between annual diffuse radiation for the TMY and the 30-year annual average is improved,while little adverse effect is produced on global horizontal radiation comparisons,indicating that the improved method is more suitable to generate the TMY data than previous studies. 展开更多
关键词 typical METEOROLOGICAL YEAR improved method weighting MODIFICATION DIFFUSE solar radiation
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VOR and CVOR Index for Health Evaluation of Typical Steppe in Inner Mongolia 被引量:2
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作者 SHAN Gui-lian JIANG Hua +4 位作者 YAN Wei-hong Liu Zhong-ling LUO Fu-cheng DUAN Xin-hui CHU Xiao-hui 《Animal Husbandry and Feed Science》 CAS 2012年第6期266-270,共5页
[Objective] The aim of this study was to evaluate the effect of livestock exclusion on the health of grassland ecosystem accurately and quantitatively. [Method] One open grazing site and five seasonal exclusion sites,... [Objective] The aim of this study was to evaluate the effect of livestock exclusion on the health of grassland ecosystem accurately and quantitatively. [Method] One open grazing site and five seasonal exclusion sites, which had the same vegetation composition (taking Leymus chinensis and Stipa krylovii as main species) and soil type, were chosen as research objects for the VOR and CVOR evaluation of the effect of open grazing and livestock exclusion on the health of typical steppes, and for building the calculation model for VOR and CVOR indices to evaluate the health of typical steppes with different exclusion periods. [ Result] The VOR and CVOR composite indices both could accurately evaluate the health of typical steppes, and the evaluation results from the both indices were quite consistent. Although the condition (C), vigor(V), organization (O) and resilience( R ) indices changed differently in different exclusion periods, the VOR and CVOR composite indices increased gradually with the peri- od of exclusion prolonged, and the health condition of typical steppe changed from "alert" level (in the open grazing and earlier exclusion period) to "healthy" level (after 13 to 20 years'exclusion). [ Conclusion] The application of exclusion was beneficial to the recovery of degraded grassland ecosystem. 展开更多
关键词 typical steppe Health evaluation GRAZING Seasonal exclusion VOR index CVOR index
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Movement and variation of four typical glaciers in the Qilian Mountains,northwestern China 被引量:1
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作者 ZheFan Jing Kun Wang Li Liu 《Research in Cold and Arid Regions》 CSCD 2015年第3期206-211,共6页
We selected four typical glaciers in the Qilian Mountains and investigated their movements and variation using advanced technologies such as remote sensing, photographic measurements, and global positioning systems. T... We selected four typical glaciers in the Qilian Mountains and investigated their movements and variation using advanced technologies such as remote sensing, photographic measurements, and global positioning systems. The velocity of glacier movements in the Qilian Mountains is relatively low, and there has been no significant variation during the past 50 years. Glacier motion has maintained a normal style. The movement velocity of Laohugou Glacier No. 12 presented a decreasing trend (by 48%) from 1960 to 2012. The movement velocity of the Qiyi Glacier also presented a decreasing trend (by 48.1%) from 1958 to 2012; it decreased by 29.4% from 1958 to 1977 and by 26.5% from 1977 to 2012. Therefore, the Qiyi Glacier's movement velocity varied greatly over the earlier 20 years (1958 1977), but presented a small decreasing trend during the latter 30 years (1977-2012). By comparing the movement velocity variation of these typical glaciers, we determined that the extent of variation was consistent among large glaciers (such as Laohugou Glacier No. 12) and small glaciers (such as the Qiyi Glacier and Yanglonghe Glacier No. 5), despite their different sizes. 展开更多
关键词 typical glaciers movement velocity VARIATION extent Qilian Mountains
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