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利用ArcGIS Python实现水系综合的方法及问题研究 被引量:2
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作者 王伟 田鸿杰 +1 位作者 李慎芳 耿晓晖 《北京测绘》 2016年第4期122-125,121,共5页
针对中小比例尺地图生产中水系数据的制图综合任务量大,缺少具有针对性的自动综合工具的技术现状,分析了现有制图综合工具处理数据的方法以及产生的后续问题,结合ArcGIS提供的制图综合工具,采用Python语言进行二次开发,实现了水系数据... 针对中小比例尺地图生产中水系数据的制图综合任务量大,缺少具有针对性的自动综合工具的技术现状,分析了现有制图综合工具处理数据的方法以及产生的后续问题,结合ArcGIS提供的制图综合工具,采用Python语言进行二次开发,实现了水系数据的自动筛选,解决了利用制图综合工具产生的拓扑错误,提高了水系数据的综合自动化水平。 展开更多
关键词 ARCGIS PYTHON 水系数据 制图综合
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地理国情河流实体编码方法研究 被引量:1
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作者 许庆领 段文华 《地理空间信息》 2019年第12期35-37,I0001,共4页
针对地理国情普查水系成果实体编码问题,进行河流流向正确性检查方法研究,提出了基于河流实体属性、流向和“唯长唯远”原则的河流实体编码方法,并通过FME平台实现了河流实体自动编码,在项目生产中得到验证,表明该解决方案是可靠、高效... 针对地理国情普查水系成果实体编码问题,进行河流流向正确性检查方法研究,提出了基于河流实体属性、流向和“唯长唯远”原则的河流实体编码方法,并通过FME平台实现了河流实体自动编码,在项目生产中得到验证,表明该解决方案是可靠、高效的,在地理国情普查水网数据优化处理中发挥巨大作用,也为实现地理国情监测水系数据深化应用和水资源相关空间分析提供了有效支撑。 展开更多
关键词 地理国情普查 河流实体编码 水系数据深化应用
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Mineralization-related geochemical anomalies derived from stream sediment geochemical data using multifractal analysis in Pangxidong area of Qinzhou-Hangzhou tectonic joint belt, Guangdong Province, China 被引量:5
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作者 张焱 周永章 +8 位作者 王林峰 王正海 何俊国 安燕飞 李红中 曾长育 梁锦 吕文超 高乐 《Journal of Central South University》 SCIE EI CAS 2013年第1期184-192,共9页
Distinguishing geochemical anomalies from background is a basic task in exploratory geochemistry. The derivation of geochemical anomalies from stream sediment geochemical data and the decomposition of these anomalies ... Distinguishing geochemical anomalies from background is a basic task in exploratory geochemistry. The derivation of geochemical anomalies from stream sediment geochemical data and the decomposition of these anomalies into their component patterns were described. A set of stream sediment geochemical data was obtained for 1 880 km 2 of the Pangxidong area, which is in the southern part of the recently recognized Qinzhou-Hangzhou joint tectonic belt. This belt crosses southern China and tends to the northwest (NE) direction. The total number of collected samples was 7 236, and the concentrations of Ag, Au, Cu, As, Pb and Zn were measured for each sample. The spatial combination distribution law of geochemical elements and principal component analysis (PCA) were used to construct combination models for the identification of combinations of geochemical anomalies. Spectrum-area (S-A) fractal modeling was used to strengthen weak anomalies and separate them from the background. Composite anomaly modeling was combined with fractal filtering techniques to process and analyze the geochemical data. The raster maps of Au, Ag, Cu, As, Pb and Zn were obtained by the multifractal inverse distance weighted (MIDW) method. PCA was used to combine the Au, Ag, Cu, As, Pb, and Zn concentration values. The S-A fractal method was used to decompose the first component pattern achieved by the PCA. The results show that combination anomalies from a combination of variables coincide with the known mineralization of the study area. Although the combination anomalies cannot reflect local anomalies closely enough, high-anomaly areas indicate good sites for further exploration for unknown deposits. On this basis, anomaly and background separation from combination anomalies using fractal filtering techniques can provide guidance for later work. 展开更多
关键词 geochemical anomalies fractal modeling principal component analysis Qinzhou-Hangzhou joint tectonic belt streamsediments
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Spatial distribution of Ice Shelf Water in front of the Amery Ice Shelf,Antarctica in summer 被引量:5
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作者 郑少军 史久新 +1 位作者 矫玉田 葛人峰 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2011年第6期1325-1338,共14页
As a unique low-temperature water mass in Antarctic coastal region, the Ice Shelf Water (ISW) is an important component for the formation of the Antarctic Bottom Water (AABW). In this paper, we present a criterion for... As a unique low-temperature water mass in Antarctic coastal region, the Ice Shelf Water (ISW) is an important component for the formation of the Antarctic Bottom Water (AABW). In this paper, we present a criterion for ISW identification based on freezing point at the sea surface, and we study spatial distribution of ISW in front of the Amery Ice Shelf (AIS) and its flow path in Prydz Bay by analyzing hydrographic data from Australian cruises in 2001 and 2002, as well as Chinese cruises in 2003, 2005, 2006, and 2008, all being made in the austral summer. The relatively cold and fresh ISW occurred as several discrete water blocks with cold cores in front of the AIS, within the depth range of 100?600 m, under the seasonal thermocline. ISW had obvious temporal and spatial variations and the spatial distribution pattern changed greatly after 2005. Most of ISW was concentrated west of 73°E during 2001 to 2003 and 2006, but it was widespread to east in 2005 and 2008. In all observation years, a small amount of cold ISW always occurs at the west end of the AIS front section, where the coldest ISW in the whole section also occurred in 2001, 2003 and 2006. Considering general cyclonic circulation pattern under the AIS, the ISW flowing out from west end of the AIS front might have experienced the longest cooling period under ice shelf, so it would have the lowest temperature. Analysis of data from meridian sections in Prydz Bay in 2003 implied that ISW in the west could spread north to the continental break along the east flank of the Fram Bank near 70.5°E, mix with the upwelling Circumpolar Deep Water and possibly contribute to the formation of AABW. 展开更多
关键词 Ice Shelf Water TEMPERATURE Amery Ice Shelf ANTARCTICA
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Observations and Modeling of Ice Water Content in a Mixed-Phase Cloud System 被引量:2
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作者 HOU Tuan-Jie LEI Heng-Chi +1 位作者 HU Zhao-Xia FENG Qiu-Juan 《Atmospheric and Oceanic Science Letters》 CSCD 2013年第4期210-215,共6页
The ice water content(IWC) distribution in a mixed-phase cloud system was investigated using Cloud-Sat data,aircraft measurements,and the Weather Research and Forecasting(WRF) model.Simulated precipitation and IWC wer... The ice water content(IWC) distribution in a mixed-phase cloud system was investigated using Cloud-Sat data,aircraft measurements,and the Weather Research and Forecasting(WRF) model.Simulated precipitation and IWC were in general agreement with rain gauge,sat-ellite,and aircraft observations.The cloud case was char-acterized by a predominant cold layer and high IWC throughout the cloud-development and precipitation stages.The CloudSat-retrieved products suggested that the IWC was distributed from 4.0 to 8.0 km,with the maximum values(up to 0.5 g m-3) at 5.0-6.0 km at the earlymature stage of cloud development.High IWC(up to 0.8 g m-3) was also detected by airborne probes at 4.2 and 3.6 km at the late-mature stage.The WRF model simulation re-vealed that the predominant riming facilitated rapid ac-cumulation of high IWC at 3.0-6.0 km. 展开更多
关键词 aircraft observation ice water content WRF
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Data-driven intelligent monitoring system for key variables in wastewater treatment process 被引量:6
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作者 Honggui Han Shuguang Zhu +1 位作者 Junfei Qiao Min Guo 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第10期2093-2101,共9页
In wastewater treatment process(WWTP), the accurate and real-time monitoring values of key variables are crucial for the operational strategies. However, most of the existing methods have difficulty in obtaining the r... In wastewater treatment process(WWTP), the accurate and real-time monitoring values of key variables are crucial for the operational strategies. However, most of the existing methods have difficulty in obtaining the real-time values of some key variables in the process. In order to handle this issue, a data-driven intelligent monitoring system, using the soft sensor technique and data distribution service, is developed to monitor the concentrations of effluent total phosphorous(TP) and ammonia nitrogen(NH_4-N). In this intelligent monitoring system, a fuzzy neural network(FNN) is applied for designing the soft sensor model, and a principal component analysis(PCA) method is used to select the input variables of the soft sensor model. Moreover, data transfer software is exploited to insert the soft sensor technique to the supervisory control and data acquisition(SCADA) system. Finally, this proposed intelligent monitoring system is tested in several real plants to demonstrate the reliability and effectiveness of the monitoring performance. 展开更多
关键词 DATA-DRIVEN Soft sensor Intelligent monitoring system Data distribution service Wastewater treatment process
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Implications of Urban Growth on Domestic Water Consumption: A Case Study of Jorhat Town, India
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作者 Mayurakshi Bhuyan Baruah 《Journal of Earth Science and Engineering》 2014年第12期736-748,共13页
This paper tries to embraces the urban growth in Jorhat town and its implications on water consumption at household's level. Urban growth is measured through the increase in the number of population and the aerial ex... This paper tries to embraces the urban growth in Jorhat town and its implications on water consumption at household's level. Urban growth is measured through the increase in the number of population and the aerial extent. It is a pathetic situation for Jorhat residents in case of domestic water consumption that due to rapid increase of population in the town, the existing water supply systems cannot cope with the current demand. So, the people of the town always struggle to collect water from other sources such as River Bhogdoi, ponds, dug well, water vendor etc., moreover, try to satisfy the limited daily household needs. The methodology adopted in this paper is involved on both primary and secondary data. The primary data has been collected through household survey pertains to 600 households from each of 19 municipal wards in Jorhat town in both pre and post monsoon seasons. To highlight the growth of population and population projection, the compound rate of growth method has been used and it is tried to link with the future water demand in Jorhat town, 展开更多
关键词 Urban Growth Domestic Water Consumption Jorhat Town.
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Robust digital image watermarking against shearing based on Haar orthogonal function system 被引量:1
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作者 DENGMing-hui HAOYan-ling SHENDong-hui 《Journal of Marine Science and Application》 2004年第1期75-80,共6页
In this paper, a robust digital watermarking method against shearing based on Haar orthogonal function system was introduced. The proposed method adopted the complete generalized orthogonal properties of Haar ortbogon... In this paper, a robust digital watermarking method against shearing based on Haar orthogonal function system was introduced. The proposed method adopted the complete generalized orthogonal properties of Haar ortbogonal function system to achieve the piece-based orthogonal transform on the image. The significant middle frequency coefficients in the transformation matrix are picked up, based on characteristics of the image visual system and the Haar orthogonal transform. The watermark is adoptively weighed to the middle frequency matrix. The method improves the validity of watermarking and shows excellent advantage against shearing attack. Experimental results show that the Haar orthogonal function system based watermark approach can provide an excellent protection under geometric attacks. 展开更多
关键词 digital watermarking Haar orthogonal function system shearing attack
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Hydrological Evaluation with SWAT Model and Numerical Weather Prediction for Flash Flood Warning System in Thailand
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《Journal of Earth Science and Engineering》 2013年第6期349-357,共9页
Flash floods are a natural disaster that occurs annually, especially in the mountainous terrain and steep slopes of northern Thailand. The current flood forecasting systems and tools are available but have low accurac... Flash floods are a natural disaster that occurs annually, especially in the mountainous terrain and steep slopes of northern Thailand. The current flood forecasting systems and tools are available but have low accuracy and efficiency. The numbers of rainfall and runoff stations are less, because the access to the station area is difficult. Additionally, the operation and maintenance costs are high. Hydrological modeling of a SWAT (Soil and Water Assessment Tool) was used in this study with the application of three days weather forecast from the NWP (numerical weather prediction), which provided temperature, relative humidity, rainfall, sunshine and wind speed. The data from NWP and SWAT were used to simulate the runoff from the Nan River in the last 10 years (2000-2010). It was found that the simulated flow rate for the main streams using data from NWP were higher than the observations. At the N64 and Nl stations, the ratios of the maximum simulated flow rate to the observations were equal to 108% and 118%, respectively. However, for the tributaries, it was found that the simulated flow rate using NWP data was lower than the observations, but, it was still within the acceptable range of not greater than 20%,6. At N65, D090201 and D090203 stations, the ratio of the maximum simulated flow rate were 90.0%, 83.0% and 86.0%, respectively. This was due to the rainfall from the NWP model being greater than the measured rainfall. The NWP rainfall was distributed all over the area while the rainfall data from the measurements were obtained from specific points. Therefore, the rain from the NWP model is very useful especially for the watershed areas without rain gauge stations. In summary, the data from the NWP can be used with the SWAT model and provides relatively sound results despite the value for the main river being slightly higher than the observed data. Consequently, the output can be used to create a flood map for flash flood warning in the area. 展开更多
关键词 Flash flood SWAT model numerical weather prediction Nan Basin Thailand.
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Vapor Pressure Measurement of Water+1,3-Dimethylimidazolium Tetrafluoroborate System
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作者 武向红 李静 +2 位作者 范丽华 郑丹星 董丽 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2011年第3期473-477,共5页
In absorption cycles,ionic liquid(IL)1,3-dimethylimidazolium tetrafluoroborate([Dmim]BF4)may be a promising absorbent of working pair using water as refrigerant.The vapor pressures of[Dmim]BF4 aqueous solution were me... In absorption cycles,ionic liquid(IL)1,3-dimethylimidazolium tetrafluoroborate([Dmim]BF4)may be a promising absorbent of working pair using water as refrigerant.The vapor pressures of[Dmim]BF4 aqueous solution were measured with the boiling-point method in the temperature range from 312.25 to 403.60 K and in the mass concentration range of 65%to 90%of[Dmim]BF4.The experimental data were correlated with an Antoine-type equation and the Non-Random Two-Liquid(NRTL)model,and the average absolute deviations between the experimental and calculated values were 1.06%and 1.15%,respectively.For the[Dmim]BF4 aqueous solution,the experimental vapor pressures show negative deviations from the calculated data with Raoult's law.For higher mass concentration of the IL,the deviation is more negative.In addition,the vapor pressures,the hydrophilicity and the solubility of[Dmim]BF4 aqueous solutions were compared with those of[Dmim]Cl aqueous solutions and [Bmim]BF4 aqueous solutions at IL-mole fraction of 0.20. 展开更多
关键词 ionic liquid 1 3-dimethylimidazolium tetrafluoroborate vapor pressure absorption cycle working pair
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Design and Description of a Photovoltaic Pumping System: Application in the Site of Adrar 被引量:1
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作者 Ahmed Mehdaoui Amar Hadj Arab Djaafar Seminar 《Journal of Environmental Science and Engineering(B)》 2012年第2期183-186,共4页
The Saharan areas and in particular the isolated sites are characterized by low levels of population, in dispersed cores, which suffer from serious problems of water supply for consumption and the irrigation. The phot... The Saharan areas and in particular the isolated sites are characterized by low levels of population, in dispersed cores, which suffer from serious problems of water supply for consumption and the irrigation. The photovoltaic pumping systems (PV) are an ideal solution for these problems. Despite the presence of several photovoltaic pumping systems (PVPS) projects, data acquisition system is still missing in most cases. In this work, the authors will present the PVPS installed at the unit of research in renewable energies in Saharan medium (URERMS, Algeria). This system will enable us to better analyze the performances ofa photovoltaic pumping system in Saharan medium. The principal elements of the chain of the photovoltaic pumping system are: a photovoltaic generator, the power conditioning system, a motor-driven pump immersed group, an electric wiring, a hydraulic infrastructure which comprises a water tank. 展开更多
关键词 Photovoltaic pumping DIMENSIONING optimization system of irrigation performances.
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Construction of lake bathymetry from MODIS satellite data and GIS from 2003 to 2011
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作者 严翼 肖飞 杜耘 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2014年第3期720-731,共12页
In recent years, sedimentation conditions in Dongting Lake have varied greatly because of signifi cant changes in runoff and sediment load in the Changjiang(Yangtze) River following the construction of Three Gorges Da... In recent years, sedimentation conditions in Dongting Lake have varied greatly because of signifi cant changes in runoff and sediment load in the Changjiang(Yangtze) River following the construction of Three Gorges Dam. The topography of the lake bottom has changed rapidly because of the intense exchange of water and sediment between the lake and the Changjiang River. However, time series information on lake-bottom topographic change is lacking. In this study, we introduced a method that combines remote sensing data and in situ water level data to extract a record of Dongting Lake bottom topography from 2003 to 2011. Multi-temporal lake land/water boundaries were extracted from MODIS images using the linear spectral mixture model method. The elevation of water/land boundary points were calculated using water level data and spatial interpolation techniques. Digital elevation models of Dongting Lake bottom topography in different periods were then constructed with the multiple heighted waterlines. The mean root-mean-square error of the linear spectral mixture model was 0.036, and the mean predicted error for elevation interpolation was-0.19 m. Compared with fi eld measurement data and sediment load data, the method has proven to be most applicable. The results show that the topography of the bottom of Dongting Lake has exhibited uneven erosion and deposition in terms of time and space over the last nine years. Moreover, lake-bottom topography has undergone a slight erosion trend within this period, with 58.2% and 41.8% of the lake-bottom area being eroded and deposited, respectively. 展开更多
关键词 Dongting Lake geomorphy time-series maps remote sensing MODIS data water level
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Research and application of GIS information system of Pipeline Network of Oil Field Water
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作者 Xinwei Hou Zhonghua Li Jianjun Xu Chuntao Zhao Jing Zhang Haibin Yao 《International Journal of Technology Management》 2016年第8期7-9,共3页
Pipeline network of oil fi eld water is established on the basis of GIS geographic information and SCADA platform, and monitorthe running state of water supply system in oil fi eld mining area in real time through dat... Pipeline network of oil fi eld water is established on the basis of GIS geographic information and SCADA platform, and monitorthe running state of water supply system in oil fi eld mining area in real time through data acquisition, instrument measurement and control,wireless network, water quantity, water pressure and other on-line monitoring equipment. The water supply system is formed, and the informationof mass water supply system is analyzed and processed in a timely manner. The system manages the entire production, management and serviceprocesses of the water supply system in a dynamic manner in order to ensure water supply safety management, and realize the modernization,intelligence and information mode operation of the water supply system in the mining area. 展开更多
关键词 GIS SCADA implementation monitoring information analysis and processing dynamic control water supply system INTELLIGENCE INFORMATIZATION
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Uncertainty and Sensitivity Analysis for the HELIOS Loop within the LACANES Benchmark
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作者 W. Jaeger V.H. Sanchez Espinoza 《Journal of Energy and Power Engineering》 2011年第6期515-524,共10页
Within the OECD/NEA Benchmarking of Thermal-Hydraulic Loop Models for Lead-Alloy Cooled Advanced Nuclear Energy Systems (LACANES), the Institute for Neutron Physics and Reactor Technology takes part in the validatio... Within the OECD/NEA Benchmarking of Thermal-Hydraulic Loop Models for Lead-Alloy Cooled Advanced Nuclear Energy Systems (LACANES), the Institute for Neutron Physics and Reactor Technology takes part in the validation process of system codes and the characterization of the thermal-hydraulic behavior of an experimental loop operated with liquid lead-bismuth-eutectics. To confirm the calculations, the results were compared to experimental data obtained from the HELIOS facility at the Seoul National University and to the results of other benchmark participants. The comparison showed that the calculations are within measurement tolerance but nevertheless discrepancies among the participants exist. The pressure drop estimation is determined by a variety of empirical correlations for the friction and the form loss coefficients. Hence, uncertainty and sensitivity measures were applied to find out which parameter is more relevant for the overall pressure drop. In the frame of this investigation, the system code TRACE and the software system for uncertainty and sensitivity, SUSA, were used. The results show that the total pressure drop varies between -30 and +15% related to the reference case. 展开更多
关键词 TRACE SUSA LACANES HELIOS pressure drop friction lead-bismuth-eutectics.
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Analysis of ice slurry production by direct contact heat transfer of air and water solution 被引量:2
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作者 Xue-jun ZHANG Ke-qing ZHENG +3 位作者 Ling-shi WANG Wei WANG Min JIANG Sheng-ying ZHAO 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2013年第8期583-588,共6页
In this paper, a novel system using direct contact heat transfer between air and water solution was proposed to generate ice slurry. The heat transfer process and the system performance were studied; energy efficiency... In this paper, a novel system using direct contact heat transfer between air and water solution was proposed to generate ice slurry. The heat transfer process and the system performance were studied; energy efficiency coefficients of 0.038, 0.053, and 0.064 were obtained using different solutions. An empirical relationship between the volumetric heat transfer coefficient U v and the main parameters was obtained by fitting the experimental data. The U v calculated from the empirical formula agreed with the experimental U v quite well with a relative error of less than 15%. Based on the empirical formula, a laboratory-scale direct contact ice slurry generator was then constructed, with practical application in mind. If the air flow rate is fixed at 200 m 3 /h, the ice production rate will be 0.091 kg/min. The experimental results also showed that the cold energy consumption of the air compressor accounted for more than half of the total amount. To improve the system energy efficiency coefficient, it is necessary to increase the air pipes insulation and the solution's thermal capacity, and also it is appropriate to utilize the free cold energy of liquefied natural gas (LNG). 展开更多
关键词 Ice slurry GENERATOR Air and water solution Direct contact Volumetric heat transfer coefficient Liquefied naturalgas (LNG)
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GRACE terrestrial water storage data assimilation based on the ensemble four-dimensional variational method PODEn4DVar:Method and validation 被引量:3
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作者 SUN Qin XIE ZhengHui TIAN XiangJun 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第3期371-384,共14页
Seasonal and interannual changes in the Earth's gravity field are mainly due to mass exchange among the atmosphere,ocean,and continental water sources.The terrestrial water storage changes,detected as gravity chan... Seasonal and interannual changes in the Earth's gravity field are mainly due to mass exchange among the atmosphere,ocean,and continental water sources.The terrestrial water storage changes,detected as gravity changes by the Gravity Recovery and Climate Experiment(GRACE) satellites,are mainly caused by precipitation,evapotranspiration,river transportation and downward infiltration processes.In this study,a land data assimilation system LDAS-G was developed to assimilate the GRACE terrestrial water storage(TWS) data into the Community Land Model(CLM3.5) using the POD-based ensemble four-dimensional variational assimilation method PODEn4 DVar,disaggregating the GRACE large-scale terrestrial water storage changes vertically and in time,and placing constraints on the simulation of vertical hydrological variables to improve land surface hydrological simulations.The ideal experiments conducted at a single point and assimilation experiments carried out over China by the LDAS-G data assimilation system showed that the system developed in this study improved the simulation of land surface hydrological variables,indicating the potential of GRACE data assimilation in large-scale land surface hydrological research and applications. 展开更多
关键词 data assimilation land surface model terrestrial water storage ensemble four-dimensional variational data assimilation method
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Design and Implementation of Spatial Data Watermarking Service System
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作者 WU Baiyan WANG Wei +2 位作者 PENG Zhiyong DU Daosheng WANG Chuanjian 《Geo-Spatial Information Science》 2010年第1期40-48,共9页
Nowadays, more and more digitalized spatial data are sold and transmitted on the Internet. Thus, there arises an important issue about copyright protection of the digital data. To solve this problem, this paper has de... Nowadays, more and more digitalized spatial data are sold and transmitted on the Internet. Thus, there arises an important issue about copyright protection of the digital data. To solve this problem, this paper has designed and implemented a spatial data watermarking service (SDWS) system which can provide a secure framework for data transaction and transfer via the Internet and protect the rights of both copyright owners and consumers at the same time. 展开更多
关键词 spatial data transaction digital watermarking watermarking protocol mobile agent digital signature
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Free-surface air entrainment in open-channel flows
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作者 WEI WangRu XU WeiLin +2 位作者 DENG Jun TIAN Zhong ZHANG FaXing 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2017年第6期893-901,共9页
In hydraulic engineering,free-surface aeration is a natural phenomenon occurring in smooth channel flows.In self-aerated flows,a key aspect that has not yet been well understood is the formation mechanism of free-surf... In hydraulic engineering,free-surface aeration is a natural phenomenon occurring in smooth channel flows.In self-aerated flows,a key aspect that has not yet been well understood is the formation mechanism of free-surface air entrainment.In this research,the process of free-surface entrapped deformation is analyzed theoretically and the critical radius of curvature for air entrainment is obtained,affected by flow mean velocity and depth.When the severity of local free-surface deformation exceeds the critical condition,the entrapped free surface encounters closure in the unstable deformation movement process,resulting in air entrainment.This inference agrees well with observed experimental results that are obtained from the processes of surface entrapped deformation and air entrainment captured by a high-speed camera-based data acquisition system.This agreement indicates that self-aeration occurs in low-velocity open-channel flows.It is also confirmed that free-surface turbulent deformation provides a mechanism for air entrainment. 展开更多
关键词 hydraulic engineering self-aeration turbulence free surface open-channel flows
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A global empirical model for mapping zenith wet delays onto precipitable water vapor using GGOS Atmosphere data 被引量:6
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作者 YAO YiBin XU ChaoQian +1 位作者 ZHANG Bao CAO Na 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第8期1361-1369,共9页
The importance of water vapor in research of global climate change and weather forecast cannot be over emphasized; therefore substantial efforts have been made in exploring the optimal methods to measure water vapor. ... The importance of water vapor in research of global climate change and weather forecast cannot be over emphasized; therefore substantial efforts have been made in exploring the optimal methods to measure water vapor. It is well-established that with a conversion factor, zenith wet delays can be mapped onto precipitable water vapor (PWV). However, the determination of the exact conversion factor depends heavily on the accurate calculation of a key variable, weighted mean temperature of the trop- osphere (Tin). AS a critical parameter in Global Positioning System (GPS) meteorology, Tm has recently been modeled into a global grid known as GWMT. The GWMT model only requires the location and the day of year to calculate Tm. Despite the advantages that the GWMT model offers, anomalies still exist in oceanic areas due to low sampling resolution. In this study, we refine the GWMT model by incorporating the global Tm grid from Global Geodetic Observing System (GGOS) and obtain an improved model, GWMT-G. The results indicate that the GWMT-G model successfully addresses the anomaly in oceanic areas in the GWMT model and significantly improves the accuracy of Tm in other regions. 展开更多
关键词 GPS meteorology zenith wet delay GWMT model GWMT-G model GGOS
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