期刊文献+
共找到43篇文章
< 1 2 3 >
每页显示 20 50 100
Instability identification on large scale underground mined-out area in the metal mine based on the improved FRBFNN 被引量:4
1
作者 Luo Zhouquan Zuo Hongyan +1 位作者 Jia Nan Wang Yiwei 《International Journal of Mining Science and Technology》 SCIE EI 2013年第6期821-826,共6页
To identify the instability on large scale underground mined-out area in the metal mine effectively,the parameters of radial basis function were determined through clustering method and the improved fuzzy radial basis... To identify the instability on large scale underground mined-out area in the metal mine effectively,the parameters of radial basis function were determined through clustering method and the improved fuzzy radial basis function neural network(FRBFNN)model of instability identification model about large scale underground mined-out area in the metal mine was built.The improved FRBFNN model was trained and tested.The results show that the improved FRBFNN model has high training accuracy and generalization ability.Parameters such as pillar area ratio,filling level and the value of rock quality designation have strong influence on instability of large scale underground mined-out area.Correctness of analysis about the improved FRBFNN model was proved by the practical application results about instability discrimination of surrounding rock in large-scale underground mined-out area of a metal mine in south China. 展开更多
关键词 Metal mine Fuzzy theory mined-out area RBF neural network DISCRIMINATION
下载PDF
Quantitative analysis of biotechnical reinforcement for a steep slope consisting of composite coal-gangue-soil medium adjacent to a mined-out area 被引量:3
2
作者 Xingping Lai Mowen Xie +1 位作者 Fenhua Ren Meifeng Cai 《Journal of University of Science and Technology Beijing》 CSCD 2005年第6期489-494,共6页
The engineering and geological characteristics of a steep slope consisting of coal gangue, rock and soil medium in Huating coal mine have been comprehensively investigated. Owing to humid weather, heavy rainfall, vege... The engineering and geological characteristics of a steep slope consisting of coal gangue, rock and soil medium in Huating coal mine have been comprehensively investigated. Owing to humid weather, heavy rainfall, vegetation and porous characteristics of the soil and rock mass, the steep slope will be destabilized and induce mud-rock flow or derive hazard easily. Firstly, based on the classical slope reinforcement theory, some regularity between the shear and displacement in the destabilized zone of the slope with or without root strength contribution is presented. Then, based on the experimental and statistical analysis of root strength, hydrological characteristics and stability status, etc., some possible biotechnical techniques for reinforcement of the steep slope have been suggested. These methods are important for quantitative analysis of destabilization of the slope and design of the biotechnical reinforcement. 展开更多
关键词 mined-out area coal-gangue-soil composite medium steep slope root-soil effect biotechnical reinforcement
下载PDF
Geochemical Stream Sediment Survey in the Wadi Umm Rilan Area,South Eastern Desert,Egypt:A New Occurrence for Gold Mineralization 被引量:2
3
作者 Mohamed Abdallah Gad DARWISH 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第3期1041-1062,共22页
The present paper investigates the stream sediment geochemistry, behavior of gold and associated elements, delineates Au-anomalous sites and defines related sources in the Wadi Umm Rilan area. Fifty three major and tr... The present paper investigates the stream sediment geochemistry, behavior of gold and associated elements, delineates Au-anomalous sites and defines related sources in the Wadi Umm Rilan area. Fifty three major and trace elements were analyzed using ICP-MS and treated applying various statistical and mapping techniques. The results showed a significant difference of mean and median Au and most chemical elements in the three portions of the area, and higher values were recorded in the western portion. Furthermore, Au-anomalous sites appeared in upper and lower parts of the Wadi Umm Rilan, along the tributaries of metavolcanic unit and near granitoid contacts. This indicates the main source of Au mineralization is related to emplacement of granitoid plutons and accompanying hydrothermal solutions. There are significant indications for the presence of more than one mineralization event forming a probable single major episode of mineralization in the area, involving Au, Pb and U mineralizations. Geology, geomorphologic aspects and weathering processes could control stream sediment geochemistry, anomalies of Au and associated elements, elemental association and their dispersion patterns. Therefore, the area is fruitful and regarded as a promising target for Au exploration, using Ag, As, Sb, Cd, Cs, and TI as pathfinder elements. 展开更多
关键词 geochemical survey stream sediments Au mineralization Wadi Umm Rilan area southEastern Desert EGYPT
下载PDF
Time function of surface subsidence based on Harris model in mined-out area 被引量:7
4
作者 Liu Xinrong Wang Junbao +2 位作者 Guo Jianqiang Yuan Hong Li Peng 《International Journal of Mining Science and Technology》 SCIE EI 2013年第2期251-254,共4页
The surface subsidence is a common environmental hazard in mined-out area. Based on careful analysis of the regularity of surface subsidence in mined-out area, we proposed a new time function based on Harris curve mod... The surface subsidence is a common environmental hazard in mined-out area. Based on careful analysis of the regularity of surface subsidence in mined-out area, we proposed a new time function based on Harris curve model in consideration of the shortage of current surface subsidence time functions. By analyzing the characteristics of the new time function, we found that it could meet the dynamic process, the velocity change process and the acceleration change process during surface subsidence. Then its rationality had been verified through project cases. The results show that the proposed time function model can give a good reflection of the regularity of surface subsidence in mined-out area and can accurately predict surface subsidence. And the prediction data of the model are a little greater than measured data on condition of proper measured data quantity, which is safety in the engineering. This model provides a new method for the analysis of surface subsidence in mined-out area and reference for future prediction, and it is valuable to engineering application. 展开更多
关键词 mined-out area Surface subsidence Time function Harris model Prediction
下载PDF
A Survey of Social Nutrition Status of the Elderly in theUrban Area of Chengdu, Sichuan Province 被引量:3
5
作者 HUANG CHENG-YU WANG RUI-SHU +2 位作者 GU HUA-QIANG CHEN HAI AND YUAN HONG-JIANG (CMB on Gerontology, West China University of the ical Sciences,Chengdu 610041, China) 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 1998年第3期277-285,共9页
The social nutrition status was investigated among 246 subjects aged 60-90 living at three urban communities in Chengdu of Sichuan Province. The questionnaire was designed to evaluate socirydeweraphic background, the ... The social nutrition status was investigated among 246 subjects aged 60-90 living at three urban communities in Chengdu of Sichuan Province. The questionnaire was designed to evaluate socirydeweraphic background, the subjects' nutrition knowledge, and the support systerns for geriatric nutrition. Fasting venous blcod was colected for the analysis of biochemical parameters. Blood pressure, bene mineral contents (BMC), body weight (BW) and they height (BH) were measured at the same time. Only 49. 7% of the subjects correctly an swered four basic questions on nutrition. Food patterns for the elder1y were simple and modest. Several nutrition-related disorders for the elderly were including high systolic bbo pressure (44. 6 % ), hyPertriglyceridemia (25. 9 % ), high diasto1ic blood pressure (25. 1% ),obesity (24. 5% ), high PBG (20. 6% ), emaciation (19. 9%), high FBG (17.9%) and osteoporosis (16. 8%). These data indicate that the support systems for the geriatric nutrition will have to be improved. 展开更多
关键词 A survey of Social Nutrition Status of the Elderly in theUrban area of Chengdu Sichuan Province PBG
下载PDF
TEDA(Tianjin Economic-technological Development Area)——A General Survey, Experience and the Plan for Future Development. 被引量:2
6
作者 Tian gui-ming Chi Chang-gui Wan Qian Spokesman, Director of the Commission Office of TEDA. Visiting Professor of Tianjin Institute of Commerce M. A. of Economies, Vice Director of the Commission Office of TEDA Deputy Chief of Secretary Section of the Commission Office of TEDA Shen Huan 《南开经济研究》 CSSCI 北大核心 1994年第S1期26-34,共9页
Since its establishment about ten years ago, TEDA has taken advantage of eachopportune time created by China’s policy of opening wider and wider to the outsideworld and the rapid economic growth to deepen its reform ... Since its establishment about ten years ago, TEDA has taken advantage of eachopportune time created by China’s policy of opening wider and wider to the outsideworld and the rapid economic growth to deepen its reform and extend its exploitation,and thus has maintained a favorable momentum and an extraordinary high speed foreconomic development. With the total economic output of the whole area raised to 展开更多
关键词 TEDA Tianjin Economic-technological Development area A General survey Experience and the Plan for Future Development
下载PDF
Survey of Sugarcane Pests in Xianggui Sugarcane Area and Countermeasures of Pest Control 被引量:1
7
作者 Xie Jiangjiang Yang Junxian +2 位作者 Luo Qingwen Yang Chunqiang Pan Qiaofei 《Plant Diseases and Pests》 CAS 2020年第1期13-16,21,共5页
Joint survey panel composed of three units investigated sugarcane borers in Xianggui sugarcane area,in order to make clear the current situation of sugarcane borers,estimate the economic loss caused by sugarcane borer... Joint survey panel composed of three units investigated sugarcane borers in Xianggui sugarcane area,in order to make clear the current situation of sugarcane borers,estimate the economic loss caused by sugarcane borers,and analyze the causes of increasingly serious occurrence of sugarcane pests.The survey results indicated that sugarcane pests occurred seriously in Xianggui sugarcane area;the average rate of borer-damaged strain was 46.54%,the average yield loss was 14.87%,and the average sucrose content loss was as high as 1.12%.The estimated results of eco-nomic damage caused by pests demonstrated that the agricultural loss was 467 million yuan,the industry loss was 856 million yuan and the national financial loss was 51 million yuan.According to the survey results,the experts of research group analyzed and summarized the causes of increasing-ly serious occurrence of sugarcane pests in Xianggui sugarcane area,and put forward the countermeasures for the prevention and control of sugar-cane pests in this area. 展开更多
关键词 Xianggui SUGARCANE area SUGARCANE PEST survey COUNTERMEASURES
下载PDF
Ecological risk assessment and early warning of heavy metal cumulation in the soils near the Luanchuan molybdenum polymetallic mine concentration area,Henan Province,central China 被引量:12
8
作者 Zhen-yu Chen Yuan-yi Zhao +3 位作者 Dan-li Chen Hai-tao Huang Yu Zhao Yu-jing Wu 《China Geology》 CAS CSCD 2023年第1期15-26,共12页
The Luanchuan molybdenum polymetallic mine concentration area is rich in mineral resources and has a long history of mining.The environmental impact of long-term mining activities cannot be ignored.It is of great sign... The Luanchuan molybdenum polymetallic mine concentration area is rich in mineral resources and has a long history of mining.The environmental impact of long-term mining activities cannot be ignored.It is of great significance to study the ecological risk and the accumulation trends of heavy metals in the soil of mining areas for scientific prevention and control of heavy metal pollution.Taking the Taowanbeigou River Basin in the mine concentration area as the research object,the ecological pollution risk and cumulative effect of heavy metals in the soil of the basin were studied by using the comprehensive pollution index method,potential ecological risk assessment method and geoaccumulation index method.On this basis,the cumulative exceeding years of specific heavy metals were predicted by using the early warning model.The comprehensive potential ecological risk of heavy metals in the soil near the Luanchuan mine concentration area is moderate,and the single element Cd is the main ecological risk factor,with a contribution rate of 53.6%.The overall cumulative degrees of Cu and Pb in the soil are“none-moderate”,Zn and Cd are moderate,Mo has reached an extremely strong cumulative level,Hg,As and Cr risks are not obvious,and the overall cumulative risks order is Mo>Cd>Zn>Cu>Pb>Hg.According to the current accumulation rate and taking the risk screening values for soil contamination of agricultural land as the reference standard,the locations over standard rates of Cu,Zn and Cd will exceed 78%in 90years,and the over standard rate of Pb will reach approximately 57%in 200 years.The cumulative exceeding standard periods of As,Cr and Hg are generally long,which basically indicates that these elements do not pose a significant potential threat to the ecological environment.Mining activities will accelerate the accumulation of heavy metals in soil.With the continuous development of mining activities,the potential pollution risk of heavy metals in the soil of mining areas will also increase. 展开更多
关键词 Soil Heavy metals Mining impact Cumulative effect Potential ecological risk Cumulation early warning Luanchuan mine concentration area Environmental geological survey engineering
下载PDF
Survey and Analysis of Common Diseases of Laboratory Monkeys, Taking Kunming Area as an Example
9
作者 Wang Hong Chen Zhigang +2 位作者 Chen Lixian Zong Faliang Li Heling 《Animal Husbandry and Feed Science》 CAS 2017年第5期289-292,321,共5页
[Objective] The paper was to understand the epidemiology of common diseases of laboratory monkeys in Kunming area. [Method]Through the investigation of sick and dead monkeys in a large-scale laboratory monkey breeding... [Objective] The paper was to understand the epidemiology of common diseases of laboratory monkeys in Kunming area. [Method]Through the investigation of sick and dead monkeys in a large-scale laboratory monkey breeding facility in Kunming area in 2014,the animals were classified depending on the main symptoms,and diseases were classified according to adult and juvenile monkeys. Data were analyzed by Office Excel 2010 software. [Result]Digestive system diseases,respiratory system diseases,trauma,reproductive system diseases,and locomotor system diseases were common disease types of laboratory monkeys in Kunming area,accounting for 47. 45%,13. 06%,12. 10%,11. 46% and 8. 92%,respectively. Common diseases included diarrhea,soft tissue injury,abortion,lobar pneumonia,dysentery,arthritis,bowel gas,chronic colitis,and extremely poor nutrition,and the ratios were 18. 47%,11. 15%,8. 91%,8. 28%,7. 96%,5. 10%,5. 10% and 5. 09%,respectively. [Conclusion]A set of scientific and reasonable measures for prevention and control of diseases is formulated,which is of great significance for improving the quantity and quality of laboratory monkeys and ensuring the accuracy of animal test results. 展开更多
关键词 Kunming area LABORATORY MONKEYS DISEASE survey and ANALYSIS
下载PDF
Ethnobotanical Survey of Appetite Suppressant Plants Used in Hauts-Bassins Areas of Burkina Faso
10
作者 Emmanuel Zongo Roland Nâg-Tiero Meda +8 位作者 Yaya Gnanou Yaya Gnanou Sami Eric Kam Benjamin Kouliga Koama Pataréyaoba Alassane Ouedraogo Eliasse Zongo Ollo Da Dramane Paré Georges Anicet Ouedraogo 《Food and Nutrition Sciences》 CAS 2022年第12期1001-1014,共14页
This study aimed to list the medicinal plants used as an appetite suppressant in Hauts-Bassins areas of Burkina Faso. An ethnobotanical survey was undertaken from September to November 2021 using a semi-structured que... This study aimed to list the medicinal plants used as an appetite suppressant in Hauts-Bassins areas of Burkina Faso. An ethnobotanical survey was undertaken from September to November 2021 using a semi-structured questionnaire. To determine well-known families and species, some indices such as Family Importance Value (FIV) and Relative Frequency of Citation (RFC) were calculated respectively. Sixty-seven traditional healers (41 men and 26 women) have been interviewed. The age group from 41 to 60 years old was more represented (47.76%). Fifty-eight (58) plant species belonging to 29 families and 53 genera were recorded to have appetite suppressant properties. Fabaceae family (25%) was the most mentioned followed by Combretaceae (12%). The most mentioned species were Guierasenegalensis (7.64%), Parkiabiglobosa (6.18%), Annona senegalensis and Gardenia erubescens (5.35% for both). Leaves and fruits had the highest frequencies of use with 41% and 25% respectively. The decoction (49.62%) was the main preparation method. The oral route was the only mode of drug administration. These results would contribute to strengthening the database on the medicinal plants used as an appetite suppressant by the traditional healers in Burkina Faso. 展开更多
关键词 Ethnobotanical survey Appetite Suppressant Plants Hauts-Bassins areas Burkina Faso
下载PDF
Effect and Prospect of Basic Geological Survey Based on Airborne Gravimetry in China 被引量:11
11
作者 LI Wenyong ZHOU Jianxin +4 位作者 XIONG Shengqing GUO Zhihong LU Wenfen XU Jianchun LIU Yanxu 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2012年第1期38-47,共10页
The airborne gravimetry was an important leap and innovation in the world's history of geophysical exploration. China's first test of the airborne gravity geological survey in the onshoreoffshore transitional area o... The airborne gravimetry was an important leap and innovation in the world's history of geophysical exploration. China's first test of the airborne gravity geological survey in the onshoreoffshore transitional area of the western and southern part of the Bohai Sea was successful and effective in geology. Based on the airborne gravity data, and combining previous ground gravity, seismic and drilling data etc., we carried out the geological interpretation by forward and inverse methods. The result shows that the airborne Bouguer gravity anomaly was clear, the fracture interpretation was reliable, and the inversion depth of the main geological interfaces was relatively accurate. This airborne gravity geological survey not only filled the exploring gaps in the onshore- offshore transitional area, and realized the geological and tectonic junction between the sea and the land, but also discovered four local gravity anomalies, 11 fractures and three sags or subsags, and so on. The good geological effect of airborne gravimetry not restricted by terrain condition shows that it can be served as a new geophysical method in the exploration of complex terrain physiognomy area such as mountain, jungle, desert, marsh, onshore-offshore transitional area and so on, and has an extensive application prospect in China in the future. 展开更多
关键词 airborne gravimetry geological survey potential application onshore-offshoretransitional area
下载PDF
Age and geochemistry of the granitoid from the Lunte area,Northeastern Zambia:Implications for magmatism of the Columbia supercontinent 被引量:3
12
作者 Hong-wei Sun Jun-ping Ren +9 位作者 Jie Wang A-lei Gu Xing-yuan Wu Fu-qing He Li-bo Zuo Chipilauka Mukofu Alphet Phaskani Dokowe Ezekiah Chikambwe Zi-jiang Liu Shi Xing 《China Geology》 2021年第4期658-672,共15页
The Paleoproterozoic tectonic evolution of the Bangweulu Block has long been controversial.Paleoproterozoic granites consisting of the basement complex of the Bangweulu Block are widely exposed in northeastern Zambia,... The Paleoproterozoic tectonic evolution of the Bangweulu Block has long been controversial.Paleoproterozoic granites consisting of the basement complex of the Bangweulu Block are widely exposed in northeastern Zambia,and they are the critical media for studying the tectonic evolution of the Bangweulu Block.This study systematically investigated the petrography,zircon U-Pb chronology,and petrogeochemistry of the granitoid extensively exposed in the Lunte area,northeastern Zambia.The results show that the granitoid in the area formed during 2051±13-2009±20 Ma as a result of Paleoproterozoic magmatic events.Geochemical data show that the granites in the area mainly include syenogranites and monzogranites of high-K calc-alkaline series and are characterized by high SiO2 content(72.68%‒73.78%)and K_(2)O/Na_(2)O ratio(1.82‒2.29).The presence of garnets,the high aluminum saturation index(A/CNK is 1.13‒1.21),and the 1.27%‒1.95%of corundum molecules jointly indicate that granites in the Lunte area are S-type granites.Rare earth elements in all samples show a rightward inclination and noticeably negative Eu-anomalies(δEu=0.16‒0.40)and are relatively rich in light rare earth elements.Furthermore,the granites are rich in large ion lithophile elements such as Rb,Th,U,and K and are depleted in Ba,Sr,and high field strength elements such as Ta and Nb.In addition,they bear low contents of Cr(6.31×10^(−6)‒10.8×10^(−6)),Ni(2.87×10^(−6)‒4.76×10^(−6)),and Co(2.62×10^(−6)‒3.96×10^(−6)).These data lead to the conclusion that the source rocks are meta-sedimentary rocks.Combining the above results and the study of regional tectonic evolution,the authors suggest that granitoid in the Lunte area were formed in a tectonic environment corresponding to the collision between the Tanzania Craton and the Bangweulu Block.The magmatic activities in this period may be related to the assembly of the Columbia supercontinent. 展开更多
关键词 PALEOPROTEROZOIC S-type granite Bangweulu Block Geological survey engineering Lunte area Northeastern Zambia
下载PDF
Response of glacier area variation to climate change in the Kaidu-Kongque river basin,Southern Tianshan Mountains during the last 20 years 被引量:4
13
作者 Lu-chen Wang Kun Yu +9 位作者 Liang Chang Jun Zhang Tao Tang Li-he Yin Xiao-fan Gu Jia-qiu Dong Ying Li Jun Jiang Bing-chao Yang Qian Wang 《China Geology》 2021年第3期389-401,共13页
Glaciers are crucial water resources for arid inland rivers in Northwest China.In recent decades,glaciers are largely experiencing shrinkage under the climate-warming scenario,thereby exerting tremendous influences on... Glaciers are crucial water resources for arid inland rivers in Northwest China.In recent decades,glaciers are largely experiencing shrinkage under the climate-warming scenario,thereby exerting tremendous influences on regional water resources.The primary role of understudying watershed scale glacier changes under changing climatic conditions is to ensure sustainable utilization of regional water resources,to prevent and mitigate glacier-related disasters.This study maps the current(2020)distribution of glacier boundaries across the Kaidu-Kongque river basin,south slope of Tianshan Mountains,and monitors the spatial evolution of glaciers over five time periods from 2000-2020 through thresholded band ratios approach,using 25 Landsat images at 30 m resolution.In addition,this study attempts to understand the role of climate characteristics for variable response of glacier area.The results show that the total area of glaciers was 398.21 km^(2)in 2020.The glaciers retreated by about 1.17 km^(2)/a(0.26%/a)from 2000 to 2020.The glaciers were reducing at a significantly rapid rate between 2000 and 2005,a slow rate from 2005 to 2015,and an accelerated rate during 2015-2020.The meteorological data shows slight increasing trends of mean annual temperature(0.02℃/a)and annual precipitation(2.07 mm/a).The correlation analysis demonstrates that the role of temperature presents more significant correlation with glacier recession than precipitation.There is a temporal hysteresis in the response of glacier change to climate change.Increasing trend of temperature in summer proves to be the driving force behind the Kaidu-Kongque basin glacier recession during the recent 20 years. 展开更多
关键词 Glacier area Climate change Remote sensing monitoring Hydrogeological survey engineering Kaidu-Kongque river basin Tianshan Mountains Center Asia-Mongolian Plateau
下载PDF
Mechanisms of salt rejection at the ice-liquid interface during the freezing of pore fluids in the seasonal frozen soil area 被引量:3
14
作者 Huan Huang Chang-fu Chen +4 位作者 Xiao-jie Mo Ding-ding Wu Yan-ming Liu Ming-zhu Liu Hong-han Chen 《China Geology》 2021年第3期446-454,共9页
Seasonal frozen soil accounts for about 53.50%of the land area in China.Frozen soil is a complex multiphase system where ice,water,soil,and air coexist.The distribution and migration of salts in frozen soil during soi... Seasonal frozen soil accounts for about 53.50%of the land area in China.Frozen soil is a complex multiphase system where ice,water,soil,and air coexist.The distribution and migration of salts in frozen soil during soil freezing are notably different from those in unfrozen soil areas.However,little knowledge is available about the process and mechanisms of salt migration in frozen soil.This study explores the mechanisms of salt migration at the ice-liquid interface during the freezing of pore fluids through batch experiments.The results are as follows.The solute concentrations of liquid and solid phases at the ice-liquid interface(C*_(L),C*_(S))gradually increased at the initial stage of freezing and remained approximately constant at the middle stage.As the ice-liquid interface advanced toward the system boundary,the diffusion of the liquid phase was blocked but the ice phase continued rejecting salts.As a result,C*_(L)and C*_(S)rapidly increased at the final stage of freezing.The distribution characteristics of solutes in ice and the liquid phases before C*_(L)and C*_(S)became steady were mainly affected by the freezing temperature,initial concentrations,and particle-size distribution of media(quartz sand and kaolin).In detail,the lower the freezing temperature and the better the particle-size distribution of media,the higher the solute proportion in the ice phase at the initial stage of freezing.Meanwhile,the increase in concentration first promoted but then inhibited the increase of solutes in the ice phase.These results have insights and scientific significance for the tackling of climate change,the environmental protection of groundwater and soil,and infrastructure protection such as roads,among other things. 展开更多
关键词 Freezing area Pore fluid Ice-liquid interface Salt rejection Solute migration Building Qianghai-Tibet Plateau Hydrogeological survey engineering China
下载PDF
Hydrogeochemical characteristics of groundwater and pore-water and the paleoenvironmental evolution in the past 3.10 Ma in the Xiong’an New Area,North China 被引量:1
15
作者 Kai Zhao Jing-xian Qi +6 位作者 Yi Chen Bai-heng Ma Li Yi Hua-ming Guo Xin-zhou Wang Lin-ying Wang Hai-tao Li 《China Geology》 2021年第3期476-486,共11页
The groundwater level has been continuously decreasing due to climate change and long-time overexploitation in the Xiong’an New Area,North China,which caused the enhanced mixing of groundwater in different aquifers a... The groundwater level has been continuously decreasing due to climate change and long-time overexploitation in the Xiong’an New Area,North China,which caused the enhanced mixing of groundwater in different aquifers and significant changes in regional groundwater chemistry characteristics.In this study,groundwater and sediment pore-water in drilling cores obtained from a 600 m borehole were investigated to evaluate hydrogeochemical processes in shallow and deep aquifers and paleo-environmental evolution in the past ca.3.10 Ma.Results showed that there was no obvious change overall in chemical composition along the direction of groundwater runoff,but different hydrochemical processes occurred in shallow and deep groundwater in the vertical direction.Shallow groundwater(<150 m)in the Xiong’an New Area was characterized by high salinity(TDS>1000 mg/L)and high concentrations of Mn and Fe,while deep groundwater had better water quality with lower salinity.The high TDS values mostly occurred in aquifers with depth<70 m and>500 m below land surface.Water isotopes showed that aquifer pore-water mostly originated from meteoric water under the influence of evaporation,and aquitard pore-water belonged to Paleo meteoric water.In addition,the evolution of the paleoclimate since 3.10 Ma BP was reconstructed,and four climate periods were determined by theδ18O profiles of pore-water and sporopollen records from sediments at different depths.It can be inferred that the Quaternary Pleistocene(0.78‒2.58 Ma BP)was dominated by the cold and dry climate of the glacial period,with three interglacial intervals of warm and humid climate.What’s more,this study demonstrates the possibilities of the applications of pore-water on the hydrogeochemical study and further supports the finding that pore-water could retain the feature of paleo-sedimentary water. 展开更多
关键词 GROUNDWATER PORE-WATER HYDROGEOCHEMISTRY Stable oxygen isotope Paleoclimate change Paleoenvironmental reconstruction Hydrogeological survey engineering Xiong’an New area North China
下载PDF
Problems and Recommendations for Rural Statistics and Survey Methods
16
作者 Chengjun ZHANG 《Asian Agricultural Research》 2014年第8期5-7,共3页
With constant deepening of the reform and opening-up,national economic system has changed from planned economy to market economy,and rural survey and statistics remain in a difficult transition period. In this period,... With constant deepening of the reform and opening-up,national economic system has changed from planned economy to market economy,and rural survey and statistics remain in a difficult transition period. In this period,China needs transforming original statistical mode according to market economic system. All levels of government should report and submit a lot and increasing statistical information. Besides,in this period,townships,villages and counties are faced with old and new conflicts. These conflicts perplex implementation of rural statistics and survey and development of rural statistical undertaking,and also cause researches and thinking of reform of rural statistical and survey methods. 展开更多
关键词 RURAL areas STATISTICS survey METHODS PROBLEMS and
下载PDF
Toward Estimating the Variance in Acoustic Surveys Based on Sampling Design
17
作者 Magnar Aksland 《Open Journal of Marine Science》 2011年第1期1-17,共17页
This paper develops a sampling method to estimate the integral of a function of the area with a strategy to cover the area with parallel lines of observation. This sampling strategy is special in that lines very close... This paper develops a sampling method to estimate the integral of a function of the area with a strategy to cover the area with parallel lines of observation. This sampling strategy is special in that lines very close to each other are selected much more seldom than under a uniformly random design for the positions of the parallel lines. It is also special in that the positions of some of the lines are deterministic. Two different variance estimators are derived and investigated by sampling different man made signal functions. They show different properties in that the estimator that estimate the biggest variance gives an error interval that, in some situations, may be more than ten times the error interval computed from the other estimator. It is also obvious that the second estimator underestimates the variance. The author has not succeeded to derive an expression for the expectation of this estimator. This work is motivated towards finding the variance of acoustic abundance estimates. 展开更多
关键词 ACOUSTIC ABUNDANCE ESTIMATION LINE surveys Sampling Design Sampling in the area Variance ESTIMATION
下载PDF
Status of China's Geological Survey and Geological Environments in 2013
18
作者 HAO Ziguo FEI Hongcai +1 位作者 HAO Qingqing Susan TURNER 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2014年第3期1020-1021,共2页
With the approach of the 45th World Earth Day,China's Ministry of Land and Resources issued the status of the Chinese geological survey and environments on 22nd April 2013.Regional geological survey in 2013 achieved ... With the approach of the 45th World Earth Day,China's Ministry of Land and Resources issued the status of the Chinese geological survey and environments on 22nd April 2013.Regional geological survey in 2013 achieved new results-(why was oceanic in twice?) polar and oceanic expedition were fully completed,a national census of geography was begun,and the security capacity of mapping geographic information was enhanced.A new idea for integrated geological survey and scientific research was proposed to enhance marine geological surveys and to improve service capabilities. 展开更多
关键词 area Status of China’s Geological survey and Geological Environments in 2013
下载PDF
Is the Farmland of China Sufficient?——Analysis Based on the Second National Land Survey
19
作者 Shuaishuai JIA 《Asian Agricultural Research》 2016年第8期69-71,共3页
According to the data of the second national land survey,the farmland area of China at the end of 2009 was 200 million mu more than the original statistical data.This raises widespread concern.Analysis is carried out ... According to the data of the second national land survey,the farmland area of China at the end of 2009 was 200 million mu more than the original statistical data.This raises widespread concern.Analysis is carried out from the perspective of task,technique,necessities and effect on China's grain security of the second national land survey.Through analysis,it can be deemed that data of the second national land survey are reliable.It overcomes defects of traditional survey projects and will be of profound significance for grasping current situations of farmland resources in China.Farmers are grain production entities,while the grain yield survey of farmers is calculated through sampling survey of per unit area yield and the sown area.Therefore,the increase in farmland area may indicate underestimation of the grain yield,and the grain security risk of China will decline accordingly. 展开更多
关键词 Grain security Land survey Per unit area yield
下载PDF
Basement interface structural characteristics beneath Jiashi strong earthquake swarm area in Xinjiang, China
20
作者 徐朝繁 段永红 +3 位作者 田晓峰 潘纪顺 张建狮 胡修奇 《Acta Seismologica Sinica(English Edition)》 CSCD 2007年第5期507-512,共6页
The seismic data obtained from high resolution seismic refraction profile in Jiashi strong earthquake swarm area in Xinjiang, China were further processed with ray hit analysis method and more complete basement interf... The seismic data obtained from high resolution seismic refraction profile in Jiashi strong earthquake swarm area in Xinjiang, China were further processed with ray hit analysis method and more complete basement interface structural characteristics beneath Jiashi strong earthquake swarm area were determined. The results show that there are two clear basement interfaces at the upper crust in Jiashi strong earthquake swarm area. The first one with buried depth ranging from 2.6 km to 3.3 km presents integral and continuous structure, and it appears an inclined plane interface and smoothly rises up toward Tianshan Mountain. The second basement interface with buried depth from 8.5 km to 11.8 km, is the antiquated crystalline basement of Tarim basin. Near the post number of 37 km, the buried depth of the crystalline basement changed abruptly by 2.5 km, which maybe result from an ultra crystalline basement fault. If taking this fault as a boundary, the crystalline basement could be divided into two parts, i.e. the southwestern segment with buried depth about 11.5 km, and the northeastern segment with buried depth approxi-mately from 8.5 km to 9.0 km. That is to say, in each segment, the buried depth changes not too much. The northeast segment rises up as a whole and upheaves slightly from southwest to northeast, which reflects the upper crustal deformation characteristics under the special tectonic background at the northwestern edge of Tarim basin. 展开更多
关键词 Jiashi strong earthquake swarm area high resolution refraction survey ray hit analysis method basement interface structure ultra crystalline basement fault
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部