检索结果-南通市图书馆

Study of the temporal and spatial patterns of drought in the Yellow River basin based on SPEI

Science China Earth Sciences 2018年第8期61卷 1098-1111页

作者： Fei WANG Zongmin WANG Haibo YANG Yong ZHAO Zhengzhou University School of Water Conservancy and Environment China Institute of Water Resources and Hydropower Research the State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin

Drought is one of the severe natural disasters to impact human society and occurs widely and frequently in China,causing considerable damage to the living environment of *** Yellow River basin(YRB)of China shows great vulnerability to drought in the major basins;thus,drought monitoring in the YRB is particularly *** on monthly data of 124 meteorological stations from 1961 to 2015,the Standardized Precipitation Evapotranspiration Index(SPEI)was used to explore the temporal and spatial patterns of drought in the *** periods and trends of drought were identified by Extreme-point Symmetric Mode Decomposition(ESMD),and the research stages were determined by Bernaola-Galvan Segmentation Algorithm(BGSA).The annual and seasonal variation,frequency and intensity of drought were studied in the *** results indicated that(1)for the past 55 years,the drought in the YRB has increased significantly with a tendency rate of-0.148(10 a)^(-1),in which the area Lanzhou to Hekou was the most vulnerable affected(-0.214(10 a)^(-1));(2)the drought periods(2.9,5,10.2 and 18.3 years)and stages(1961–1996,1997–2002 and 2003–2015)were characterized and detected by ESMD and BGSA;(3)the sequence of drought frequency was summer,spring,autumn and winter with mean values of 71.0%,47.2%,10.2%and 6.9%,respectively;and(4)the sequence of drought intensity was summer,spring,winter and autumn with mean values of 0.93,0.40,0.05 and 0.04,respectively.

关键词： Yellow River basin(YRB) Drought Standardized Precipitation Evapotranspiration Index(SPEI) Extreme-point Symmetric Mode Decomposition(ESMD) Bernaola-Galvan Segmentation Algorithm(BGSA)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Estimation of dry deposition fluxes of major inorganic species by canopy throughfall approach

引用

Chinese Science Bulletin 2006年第15期51卷 1818-1823页

作者： JIN Lei SHAO Min ZENG Limin ZHAO Dawei TANG Dagang Beijing Municipal Environmental monitoring Centre Beijing 100044 China State Joint key laboratory of Environmental simulation and Pollution Control College of Environmental Sciences Peking University Beijing 100871 China Chongqing Institute of Environmental Science and monitoring Chongqing 400020 China Institute of Atmosphere Chinese Research Academy of Environmental Sciences Beijing 100012 China

Dry deposition in China has not yet been intensively studied even though it constitutes an important pathway for acid deposition. The total deposition was monitored at Tieshanping catchment, a regional remote site in Chongqing City. The dry deposition loads of sulphur, calcium and nitrogen are estimated by using a canopy throughfall approach. The results indicate that the annual dry deposition loads of sulphur and calcium at Tieshanping site are much higher than those measured in forestry areas in other countries, while the dry deposition flux of ni- trogen is at a comparable level. The dry deposition loads of sulphur, calcium and nitrogen are all higher than the wet deposition loads. Applying a canopy budget model has proven that the routine, simplified canopy throughfall approach may underestimate the dry deposition flux of nitrogen-containing species.

关键词：净降水量酸沉降量化干沉积无机化学种

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Ontology-Based BERT Model for Automated Information Extraction from Geological Hazard Reports

引用

Journal of Earth Science 2023年第5期34卷 1390-1405页

作者： Kai Ma Miao Tian Yongjian Tan Qinjun Qiu Zhong Xie Rong Huang Hubei key laboratory of Intelligent Vision Based monitoring for Hydroelectric Engineering China Three Gorges UniversityYichang 443002China College of Computer and Information Technology China Three Gorges UniversityYichang 443002China Hubei Engineering Technology Research Center for Farmland Environment monitoring China Three Gorges UniversityYichang 443002China School of Computer Science China University of GeosciencesWuhan 430074China key laboratory of Urban Land Resources monitoring and simulation Ministry of Natural ResourcesShenzhen 518034China Beijing key laboratory of Urban Spatial Information Engineering Beijing 100045China College of Economics and Management China Three Gorges UniversityYichang 443002China

Geological knowledge can provide support for knowledge discovery, knowledge inference and mineralization predictions of geological big data. Entity identification and relationship extraction from geological data description text are the key links for constructing knowledge graphs. Given the lack of publicly annotated datasets in the geology domain, this paper illustrates the construction process of geological entity datasets, defines the types of entities and interconceptual relationships by using the geological entity concept system, and completes the construction of the geological corpus. To address the shortcomings of existing language models(such as Word2vec and Glove) that cannot solve polysemous words and have a poor ability to fuse contexts, we propose a geological named entity recognition and relationship extraction model jointly with Bidirectional Encoder Representation from Transformers(BERT) pretrained language model. To effectively represent the text features, we construct a BERT-bidirectional gated recurrent unit network(BiGRU)-conditional random field(CRF)-based architecture to extract the named entities and the BERT-BiGRU-Attention-based architecture to extract the entity relations. The results show that the F1-score of the BERT-BiGRU-CRF named entity recognition model is 0.91 and the F1-score of the BERT-BiGRU-Attention relationship extraction model is 0.84, which are significant performance improvements when compared to classic language models(e.g., word2vec and Embedding from Language Models(ELMo)).

关键词： ontology BERT model name entity recognition relation extraction knowledge graph

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Optimal resource allocation for transmission diversity in multi-radio access networks:a coevolutionary genetic algorithm approach

引用

Science China(Information Sciences) 2014年第2期57卷 99-112页

作者： FAN WenHao LIU YuanAn WU Fan Beijing key laboratory of Work Safety Intelligent monitoring Beijing University of Posts and Telecommunications Wireless Communications and EMC laboratory School of Electronic EngineeringBeijing University of Posts and Telecommunications

The next generation wireless communication systems aim at supporting enhanced diversified network access and data transmission abilities via the cooperative integration and unified management of various radio access technologies(RATs).The resource allocation is the core component leading the network system and mobile terminals to the service robustness and performance *** this paper,a numeric optimization model for optimizing terminals’transmission power and allocated RAT bandwidth for maximizing system capacity is proposed with the focal consideration of the multi-radio transmission diversity for parallel transmission through multiple links from diferent RATs,and diferent terminal characteristics on RAT ***,we design a centralized and periodic scheduling algorithm including an improved coevolutionary genetic algorithm for efciently solving the optimization *** results demonstrate that our propose algorithm can distinctly enhance the system performance and improve the computational efciency.

关键词： multi-radio access radio resource management multi-radio transmission diversity Lagrangian method coevolutionary algorithm genetic algorithm

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Improvement of cloud microphysical parameterization and its advantages in simulating precipitation along the Sichuan-Xizang Railway

引用

Science China Earth Sciences 2024年第3期67卷 856-873页

作者： Xiaoqi XU Zhiwei HENG Yueqing LI Shunjiu WANG Jian LI Yuan WANG Jinghua CHEN Peiwen ZHANG Chunsong LU China Meteorological Administration Transportation Meteorology key laboratory Nanjing Joint Institute for Atmospheric SciencesNanjing 210041China Heavy Rain and Drought-Flood disasters in Plateau and Basin key laboratory of Sichuan Province Institute of Plateau MeteorologyCMAChengdu 610072China State key laboratory of Disaster Weather Chinese Academy of Meteorological SciencesBeijing 100081China Collaborative Innovation Center for Western Ecological Safety Lanzhou UniversityLanzhou 730000China China Meteorological Administration Aerosol-Cloud and Precipitation key laboratory and Collaborative Innovation Center on Forecast and Evaluation of Meteorological disasters(CIC-FEMD) Nanjing University of Information Science and TechnologyNanjing 210044China

The Sichuan-Xizang Railway is an important part of the railway network in China, and geological disasters, such as mountain floods and landslides, frequently occur in this region. Precipitation is an important cause of these disasters;therefore,accurate simulation of the precipitation in this region is highly important. In this study, the descriptions for uncertain processes in the cloud microphysics scheme are improved;these processes include cloud droplet activation, cloud-rain autoconversion, rain accretion by cloud droplets, and the entrainment-mixing process. In the default scheme, the cloud water content of different sizes corresponds to the same cloud droplet concentration, which is inconsistent with the actual content;this results in excessive cloud droplet size, unreasonable related conversion rates of microphysical process(such as cloud-rain autoconversion), and an overestimation of precipitation. Our new scheme overcomes the problem of excessive cloud droplet size. The processes of cloudrain autoconversion and rain accretion by cloud droplets are similar to the stochastic collection equation, and the mixing mechanism of cloud droplets is more consistent with that occurred during the actual physical process in the cloud. Based on the new and old schemes, multiple precipitation processes in the flood season of 2021 along the Sichuan-Xizang Railway are simulated, and the results are evaluated using ground observations and satellite data. Compared to the default scheme, the new scheme is more suitable for the simulation of cloud physics, reducing the simulation deviation of the liquid water path and droplet radius from 2 times to less than 1 time and significantly alleviating the overestimation of precipitation intensity and range of precipitation center. The average root-mean-square error is reduced by 22%. Our results can provide a scientific reference for improving precipitation forecasting and disaster prevention in this region.

关键词： The Sichuan-Xizang Railway Cloud microphysics Precipitation Model improvement

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Evaluation of CMPAS precipitation products over Sichuan,China

引用

Atmospheric and Oceanic Science Letters 2022年第2期15卷 47-53页

作者： Shiying Li Xiaolong Huang Wei Wu Bing Du Yuhe Jiang Sichuan Meteorological Observation and Data Center Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan ProvinceChengduChina

High-quality and high-resolution precipitation data are the basis for mesoscale numerical weather forecasting,model verification,and hydrological monitoring,which play an important role in meteorological and hydrological disaster prevention and *** this study,high-density rain gauge data are used to evaluate the fusion accuracy of the China Meteorological Administration Multisource Precipitation Analysis System(CMPAS),and four CMPAS products with different spatial and temporal resolution and different data sources are compared,to derive the applicability of *** show that all the CMPAS products show high accuracy in the Sichuan Basin,followed by Panxi Area and the western Sichuan *** errors of the four products all rise with the increase in *** overestimates precipitation in summer and autumn and underestimates it in spring and ***,the applicability of these fused data in the Sichuan Basin is quite *** to the lack of observations and the influence of the terrain and meteorological conditions,the evaluation of CMPAS in the plateau area needs further analysis.

关键词： Multisource precipitation products High-resolution precipitation CMPAS Applicability assessment

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effects of future land use change on the regional climate in China

引用

Science China Earth Sciences 2015年第10期58卷 1840-1848页

作者： HUA WenJian CHEN HaiShan LI Xing Collaborative Innovation Center on Forecast and Evaluation of Meteorological disasters/key laboratory of Meteorological Disaster Ministry of Education Nanjing University of Information Science & Technology State key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences International Joint laboratory on Climate and Environment Change Nanjing University of Information Science & Technology

Land use and land cover change(LUCC)is one of the important human forcing on ***,it is difficult to infer how LUCC will affect climate in the future from the effects of previous LUCC on regional climates in the ***,based on the land cover data recommended by the Coupled Model Intercomparison Project Phase 5(CMIP5),a regional climate model(Reg CM4)was used to investigate the climate effects of future land use change over *** 15-year simulations(2036–2050),one with the current land use data and the other with future land cover scenario(2050)were *** is noted that future LUCC in China is mainly characterized by the transition from the grassland to the *** suggest that the magnitudes and ranges of the changes in temperature and precipitation caused by future LUCC show evident seasonality,which are more prominent in summer and *** response of climate to future LUCC mainly happens in Northeast China,North China,the Hetao Area,Eastern Qinghai-Tibetan Plateau and South *** investigation shows that future LUCC can also produce significant impacts on the atmospheric *** results in abnormal southwesterly wind over extensive areas from the Indian peninsula to the coasts of the South China Sea and South China through the Bay of ***,Indian tropical southwest monsoons and South Sea southwest monsoons will both be strong,and the abnormal water vapor convergence from the South China Sea and the Indian Ocean will result in more precipitation in South China.

关键词： land use change regional climate numerical simulation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Risk Identification of Seismic Landslides by Joint Newmark and RockFall Analyst Models: A Case Study of Roads Affected by the Jiuzhaigou Earthquake

引用

International Journal of Disaster Risk Science 2018年第3期9卷 392-406页

作者： Xiliu Yue Shaohong Wu Yunhe Yin Jiangbo Gao Jingyun Zheng Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Key Laboratory of Land Surface Pattern and Simulation University of Chinese Academy of Sciences

Geological disasters are a great threat to people's lives and property. At present, it is difficult to evaluate quantitatively the cascading effects of regional geological disasters, and the development of new methods for such evaluation is much needed. In this study, the authors have developed a joint procedure that couples the Newmark model and the RockFall Analyst model based on a GIS platform in order to identify the impact of seismic landslides on roads. The new method effectively combines two processes—seismic landslide occurrence probability analysis and mass movement trajectory simulation. The permanent displacement derived from the Newmark model is used to identify potential source areas of *** on the RockFall Analyst model, the possible impact of mass movement on the roads can be simulated. To verify the reliability of the method, the landslides induced by the 2017 Jiuzhaigou Earthquake were taken as a case *** results suggest that about 21.37% of the study area is at high risk of seismic landslides, and approximately 3.95 km of road sections are at extremely high risk of large landslides. The simulated area is consistent with the distribution of disasters revealed by post-earthquake remote sensing image interpretation and field investigation in existing studies. This indicates that the procedure, which joins the Newmark and RockFall models, has a high reliability for risk identification and can be applied to seismic landslide risk assessment and prediction in similar areas.

关键词： China Jiuzhaigou earthquake Newmark model Risk identification RockFall analyst model Seismic landslide

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Analysis of Emerging Contaminants in Surface Water,Aquaculture Ponds and Wastewater Treatment Facilities in the Taige Canal Basin

引用

Chemical Research in Chinese Universities 2023年第3期39卷 516-524页

作者： CHENG Xue JIANG Xinshu LIU Liquan HUANG Jun State key Joint laboratory of Environmental simulation and Pollution Control(SKLESPC) Beijing Key Laboratory for Emerging Organic Contaminants Control(BKLEOC)Beijing Laboratory for Environmental Frontier Technologies(BLEFT)School of EnvironmentTsinghua UniversityBeijing100084P.R.China

Emerging contaminants(ECs)have aroused great concerns due to their widespread presence as well as their potential health and ecological *** monitoring data about ECs in Chinese rural areas are still *** this study,Taige Canal basin was selected as a typical rural area for a pilot *** occurrence of ECs,including pharmaceutical and personal care products(PPCPs),pesticides,plasticizers and flame retardants,in surface water and aquaculture ponds,as well as in wastewater treatment facilities,was comprehensively *** effectiveness of rural decentralized wastewater treatment facilities and centralized wastewater treatment plant(WWTP)in removing ECs was also *** 126 commonly used pesticides for target analysis,25 compounds were detected in surface water with high frequency of>80%.Besides,55 PPCPs,21 pesticides and 18 other industrial products were identified by non-target analysis using high resolution mass spectrometry(HRMS).Totally 18 compounds were detected in surface water with a frequency of>60%and 6 of them were found in all samples,including irbesartan,valsartan,propazine,buprofezin,bis(2-ethylhexyl)phthalate(DEHP)and tri-(2-chloroisopropyl)phosphate(TCPP),with mean concentrations of 3022,195,125,218,3738 and 545 ng/L,*** are 29 compounds(11 PPCPs,8 pesticides and 10 other industrial products)detected in water samples from the aquaculture ponds,of which 13 compounds were found in all three *** removal efficiencies of ECs in wastewater treatment facilities are generally limited,except valsartan(82%–86%),nobiletin(100%)and diisodecylphthalate(100%)were found to be significantly removed.

关键词： Emerging contaminant Pharmaceutical and personal care product Pesticide Plasticizer Non-target analysis

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Design and implementation of a high-efficiency concurrent dual-band power amplifier

引用

The Journal of China Universities of Posts and Telecommunications 2014年第6期21卷 94-99页

作者： YANG Qian-kun LIU Yuan-an YU Cui-ping LI Shu-lan LI Jiu-chao Beijing key laboratory of Work Safety Intelligent monitoring Beijing University of Posts and Telecommunications School of Electronic Engineering Beijing University of Posts and Telecommunications

This paper studies the behaviors of power amplifier（PA） driven by a single-carrier continuous wave（CW） signal and a two-carrier CW signal both in theory and simulation, and explains why the traditional dual-band PA failed to perform satisfactory results when a two-carrier CW signal is applied to, called concurrently. Besides that, an evaluation standard of concurrent dual-band PA was presented to value its performance. Solution was given with design and fabrication of a concurrent 1.85 GHz/2.65 GHz class F PA, employing a 10 W GaN HEMT device from Cree, CGH40010, whose measurement shows the saturated output power is 40.6 d Bm and 40.8dB m with drain efficiencies（DE） of 77.4% and 75.3% at 1.85 GHz and 2.65 GHz, respectively. On the other hand, we see that the peak DE achieves 59.7% with an output power of 39.9 dB m in concurrent mode, which follows up with the standard.

关键词： PA concurrent dual-band intermodulation and harmonic high efficiency

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：