期刊文献+
共找到2,442篇文章
< 1 2 123 >
每页显示 20 50 100
Application of Different Image Processing Techniques on Aster and ETM+ Images for Exploration of Hydrothermal Alteration Associated with Copper Mineralizations Mapping Kehdolan Area (Eastern Azarbaijan Province-Iran) 被引量:2
1
作者 Golchin Hajibapir Mohammad Lotfi +1 位作者 Afshar Zia Zarifi Nima Nezafati 《Open Journal of Geology》 2014年第11期582-597,共16页
The Kehdolan area is located at 20 kilometers to the?south-east of Dozdozan Town (Eastern Azarbaijan Province). According to structural geology, volconic rocks are situated in Alborz-Azarbyjan zone, and faults?are?obs... The Kehdolan area is located at 20 kilometers to the?south-east of Dozdozan Town (Eastern Azarbaijan Province). According to structural geology, volconic rocks are situated in Alborz-Azarbyjan zone, and faults?are?observed?in?the?same direction to this system with SE-NW trend. The results show that kaolinite alteration trend with Argilic and propylitic veins?is the?same direction with SW-NE faults in this area. Therefore, these faults with these trends can be considered as the mineralization control for determination of the alterations. Different image processing techniques,?such as false color composite?(FCC), band ratios, color ratio composite?(CRC), principal component?analysis?(PCA), Crosta technique, supervised spectral angle mapping?(SAM), are used for?identification of the alteration zones associated with copper mineralization. In this project ASTER?data are process and spectral analysis to fit for recognizing intensity and kind of argillic, propylitic,?philic, and ETM+ data?which?are process and to fit for iron oxide and relation to metal mineralization of the area. For recognizing different alterations of the study area, some chemical and mineralogical analysis data from the samples showed that ASTER data and ETM+ data were?capable of hydrothermal alteration mapping with copper mineralization.?Copper mineralization in the region is in agreement with argillic alteration. SW-NE trending faults controlled the mineralization process. 展开更多
关键词 Kehdolan area False COLOR COMPOSITE Band ratios COLOR ratio COMPOSITE Principal Component Analysis Crosta Technique Supervised Spectral Angle MAPPING ASTER DATA ETM+ DATA Alteration
下载PDF
Coral Ba/Ca and Mn/Ca Ratios as Proxies of Precipitation and Terrestrial Input at the Eastern Offshore Area of Hainan Island
2
作者 JIANG Qiaowen CAO Zhimin +3 位作者 WANG Daoru LI Yuanchao WU Zhongjie NI Jianyu 《Journal of Ocean University of China》 SCIE CAS CSCD 2017年第6期1072-1080,共9页
Geochemical ratios in coral reef skeletons could be used as proxies to reconstruct past climatological and environmental records in data-poor regions. Using a 103-year data set(1902 to 2005), the annual variations in ... Geochemical ratios in coral reef skeletons could be used as proxies to reconstruct past climatological and environmental records in data-poor regions. Using a 103-year data set(1902 to 2005), the annual variations in Ba/Ca and Mn/Ca ratios of Porites lutea skeletons at an eastern offshore area of Hainan Island(19?12'28.4''N, 110?37'38.8''E) were analyzed using inductively coupled plasma-optic emission spectrometry(ICP-OES). The analysis results showed that Ba/Ca ratios varied from a minimum of 3.120 μmol mol^(-1) in 1903 to a maximum of 10.064 μmol mol^(-1) in 1944, with an average of 5.256 μmol mol^(-1). Mn/Ca ratios varied from 0.206 to 5.708 μmol mol^(-1) with an annual average of 1.234 μmol mol^(-1), with peak values in 2001, 1964 and 1932, that correlated with strong rainfall events caused by typhoons. Variation in Ba/Ca and Mn/Ca ratios were compared with available river discharge and precipitation records, providing insight into past climatological events. Human activities and their indirect effects could impact the strength of the relationship between Ba/Ca and Mn/Ca ratios and observed precipitation and terrestrial input in the future. 展开更多
关键词 PORITES lutea eastern offshore area of Hainan Island Ba/Ca and Mn/Ca ratios terrigenous INPUT PRECIPITATION climate proxy records
下载PDF
Correlation between Surface Area Ratio of Medial to Lateral Tibial Plateau and Knee Alignment in Adults
3
作者 Song GONG Li-zhi HAN +3 位作者 Tian-lun GONG Yi-hu YI Ruo-yu WANG Wei-hua XU 《Current Medical Science》 SCIE CAS 2022年第3期577-583,共7页
Objective This study aimed to investigate the correlation between the surface area ratio of medial tibial plateau(MTP)to lateral tibial plateau(LTP)and the mechanical tibiofemoral angle(mTFA).Methods Lower limb comput... Objective This study aimed to investigate the correlation between the surface area ratio of medial tibial plateau(MTP)to lateral tibial plateau(LTP)and the mechanical tibiofemoral angle(mTFA).Methods Lower limb computed tomography(CT)images were collected at our hospital.Then,the original CT data were analyzed and reconstructed using medical image processing software.The proximal and distal centres of the femur and tibia were marked.The surface areas of MTP and LTP were identified using image processing software.GraphPad Prism 8.0.2 was used to perform the statistical analysis.Results The surface area ratio of MTP to LTP was significantly correlated with the mTFA in all patients(P<0.0001),male group(P<0.0001),female group(P<0.0001),varus group(P<0.0001),and valgus group(P=0.002).Furthermore,the surface area of MTP and LTP was significantly greater in the male group than in the female group(P<0.0001).There was significant difference in the surface area of the MTP between the varus and valgus groups(P<0.0001).Significant difference was also observed in the surface area ratio of MTP to LTP between the varus and valgus groups(P<0.0001).Conclusion The surface area ratio of MTP to LTP was correlated with the mTFA.Within a certain range,the smaller the mTFA,the greater the surface area ratio of MTP to LTP.For patients undergoing total knee arthroplasty,of whom the surface area of the MTP was basically equal to that of the LTP,it is recommended that the osteotomy should be performed in accordance with mechanical alignment standards,and that a symmetrical tibial plateau prosthesis should be used.For patients whose surface area of MTP is significantly greater than that of the LTP,it is recommended that the osteotomy should be performed in accordance with kinematic alignment standards,and that an anatomical tibial plateau prosthesis should be used. 展开更多
关键词 knee alignment medial tibial plateau lateral tibial plateau surface area ratio prosthesis types total knee arthroplasty
下载PDF
Phase-Space Areas of the Body Motion in the Solar System Deduced from the Bohr-Sommerfeld Atomic Theory and Approximate Invariance of Their Ratios for the Pairs of Planets and Satellites
4
作者 Stanislaw Olszewski Tadeusz Kwiatkowski 《Journal of Modern Physics》 2012年第9期1142-1151,共10页
Energy-time and momentum-position phase spaces defined by the electron orbits in the hydrogen-like atom exhibit special properties of equivalence. It is demonstrated that equivalence of the same kind can be obtained f... Energy-time and momentum-position phase spaces defined by the electron orbits in the hydrogen-like atom exhibit special properties of equivalence. It is demonstrated that equivalence of the same kind can be obtained for the phase-space areas defined by the orbit pairs of planets, or satellites, which compose the solar system. In the choice of the examined areas it is useful to be guided by the Bohr-Sommerfeld atomic theory. 展开更多
关键词 ratios of the PHASE-SPACE areas and THEIR INVARIANCE Planets and SATELLITES Bohr-Sommerfeld Atomic Theory
下载PDF
A Study of the Correlation between the Concentration of Particulate Matter and Green Area Ratio Measured through a Portable Monitoring System: With Particular Focus on the Case of Dalseo-Gu, Daegu Metropolitan City
5
作者 Kyungsu Son Sanghun Baek +1 位作者 Eungho Jung Daewuk Kim 《Journal of Environmental Protection》 2022年第1期84-96,共13页
This study analyzed the relationship between the measured concentration of particulate matter (PM) and green area, which is an important spatial factor affecting urban PM concentration and even more carbon neutral in ... This study analyzed the relationship between the measured concentration of particulate matter (PM) and green area, which is an important spatial factor affecting urban PM concentration and even more carbon neutral in cities. In order to investigate the effects of green area, the green area ratio (GAR) is used and correlated with particulate matter. As a result of analyzing the correlation between GAR and PM concentration using the measured PM data, it was found that there was a positive correlation between the two variables. Hence, the higher the GAR, the lower the PM concentration. It can be said that the introduction of spatial elements with high GAR scores, such as parks and forests in cities, is effective in reducing PM concentration. In this study, a portable PM monitoring system using a vehicle for PM measurement was also established and operated. As a result, it was found that a PM monitoring system using a light-scattering sensor is an effective PM measurement method that can be used at the local government level. It was also found that a follow-up study is needed in the future to identify the PM mitigation functions of urban green areas according to the detailed characteristics of green areas as well as various environmental factors. This study can be used in air quality improvement activities and efforts as reference data by policy decision makers and in the field of environmental planning associated with the removal of airborne particulate matter pollution in urban areas. 展开更多
关键词 Particulate Matter (PM) CORRELATION Green area ratio (GAR) Monitoring System
下载PDF
A Study on Average Velocity Ratios(V_P/V_S) in the Hohhot-Baotou Area
6
作者 Han Xiaoming Zhang Fan 《Earthquake Research in China》 2012年第1期118-127,共10页
The geological structure is complex in the Hohhot-Baotou area.Several earthquakes with MS≥6.0 have occurred in the area in history.This article selected the Hohhot-Baotou area as the study region and divided it into ... The geological structure is complex in the Hohhot-Baotou area.Several earthquakes with MS≥6.0 have occurred in the area in history.This article selected the Hohhot-Baotou area as the study region and divided it into 2 sub-regions,each with a spatial scope of 3°×2°,according to the spatial distribution of ML≥1.0 earthquakes occurring between January 2001 and April 2010,and the layout of the seismic network in the study region.Average velocity ratios of respective sub-regions were calculated,and comparative analysis was made on their temporal and spatial variations.Results show that there are slight differences between sub-regions in the variation amplitude of average velocity ratio curves over time,which mostly remains between 2.5% to 2.584%.In the Hohhot area,the average velocity ratio is 1.722,significantly lower than the average velocity ratio of 1.733 in the Baotou area.We preliminarily concluded that this was related to the distribution of fault structures and properties of underground media in the Hohhot area. 展开更多
关键词 Hohhot-Baotou area Average velocity ratio (Vp/Vs) Spatio-temporalanalysis
下载PDF
CARBON EMISSION-BASED MEASUREMENT OF FLOOR AREA RATIO BONUS FOR RESIDENTIAL GREEN BUILDINGS IN CHINA
7
作者 Yanhui Mao Xuemei Gong Yun Ye 《Journal of Green Building》 2018年第2期84-97,共14页
Green building development in China relies mainly on compulsory measures that lack incentive policies to motivate the enthusiasm of real estate developers.A floor area ratio bonus is encouraged by the Chinese State Co... Green building development in China relies mainly on compulsory measures that lack incentive policies to motivate the enthusiasm of real estate developers.A floor area ratio bonus is encouraged by the Chinese State Council.In order to ensure the feasibility of a reward quota,residential buildings that met the requirement for energy efficiency during the official assessment in Ningbo in 2014 were selected as research objects.The amount of energy and water savings in terms of the Assessment Standard for Green Building is converted into carbon emissions.Carbon emissions of different star-rated green buildings are then measured in accordance with the actual water and power consumption of residential dwellings in 2014.A regression equation is set up concerning the floor area ratio and index for residential land per capita.A carbon emission-based method is proposed for measuring the reward quota associated with floor area ratio and recommendations are given for development using green building. 展开更多
关键词 green building carbon emission index for residential land per capita floor area ratio
下载PDF
Identified the hydrochemical and the sulfur cycle process in subsidence area of Pingyu mining area using multi-isotopes combined with hydrochemistry methods
8
作者 Hui-Meng Su Fa-Wang Zhang +4 位作者 Jing-Yu Hu Jin-Feng Lei Wei Zuo Bo Yang Yu-Hua Liu 《Journal of Groundwater Science and Engineering》 2024年第1期62-77,共16页
Groundwater serves as an important water source for residents in and around mining areas.To achieve scientific planning and efficient utilization of water resources in mining areas,it is essential to figure out the ch... Groundwater serves as an important water source for residents in and around mining areas.To achieve scientific planning and efficient utilization of water resources in mining areas,it is essential to figure out the chemical formation process and the ground water sulfur cycle that transpire after the coal mining activities.Based on studies of hydrochemistry and D,^(18)O-H_(2)O,^(34)S-SO_(4)isotopes,this study applied principal component analysis,ion ratio and other methods in its attempts to reveal the hydrogeochemical action and sulfur cycle in the subsidence area of Pingyu mining area.The study discovered that,in the studied area,precipitation provides the major supply of groundwater and the main water chemistry effects are dominated by oxidation dissolution of sulfide minerals as well as the dissolution of carbonate and silicate rocks.The sulfate in groundwater primarily originates from oxidation and dissolution of sulfide minerals in coal-bearing strata and human activities.The mixed sulfate formed by the oxidation of sulfide minerals and by human activities continuously recharges the groundwater,promoting the dissolution of carbonate rock and silicate rock in the process. 展开更多
关键词 PCA Ion ratio Water chemistry Sulfide minerals Multi-isotopes Subsidence area of mining area
下载PDF
Effects of Different Irrigation Times and Nitrogen Fertilizer Application on Leaf Area Index and Grain Yield of ‘Yujiao 5' 被引量:1
9
作者 倪永静 贺群岭 +4 位作者 李金沛 朱培培 胡新 张丽琴 王世杰 《Agricultural Science & Technology》 CAS 2015年第9期1969-1977,共9页
To provide "more reasonable, more saving and more efficient" water and fertilizer application proposals, taking ‘Yujiao 5' as the experimental material, the effects of different irrigation times and nitrogen appli... To provide "more reasonable, more saving and more efficient" water and fertilizer application proposals, taking ‘Yujiao 5' as the experimental material, the effects of different irrigation times and nitrogen application treatments on the leaf area index and yield of wheat were studied using three-factor split plot method. The results showed that irrigation times, nitrogen application rate and the ratio of basa to topdressed nitrogen respectively had significant effects on the leaf area index, the yield and component factors of wheat. Under the treatment of W1(irrigation before sowing), the leaf area index showed a positive linear correlation with nitrogen application rate; under the treatments of W2(irrigation before sowing and at jointing stage) and W3(irrigation before sowing, at jointing stage and at grain filling stages),the leaf area index showed a positive linear correlation with nitrogen application rate at the jointing stage, booting stage and heading stage; 20 d after heading, the leaf area index showed a quadric curve relationship with nitrogen application rate at these stages, and the LAI of N3R2 was the highest. Under different irrigation times,the yield, ear number and kernels per ear showed quadric curve relationship with nitrogen application rate, 1 000-seed weight showed the trend of linear decrease with the increase of nitrogen application rate. Under the treatment combination of irrigation before sowing, at jointing stage and at grain filling stage, nitrogen application rate at 240 kg/hm^2 and the ratio of basal to topdressed nitrogen of 5:5, the grain yield(8 609.60 kg/hm^2), ear number(688.2×104/hm^2) and kernel number per ear(37.9 grains) reached the highest value at W3N3R2, and the grain yield of W3N3R2 increased by 144.8% compared to the W1N0. In conclusion, in Eastern Henan where the rainfall is insufficient at the late growth stage of wheat, the irrigation-saving space in wheat production is relatively small, but the nitrogen-saving space is relatively large. 展开更多
关键词 IRRIGATION Nitrogen fertilizer The ratio of basal to topdressed nitrogen ‘Yujiao 5' Leaf area index Grain yield
下载PDF
Segmented taper equations with crown ratio and stand density for Dahurian Larch (Larix gmelinii) in Northeastern China 被引量:17
10
作者 JIANG Li-chun LIU Rui-long 《Journal of Forestry Research》 SCIE CAS CSCD 2011年第3期347-352,共6页
Segmented taper equation was selected to model stem profile of Dahurian larch (Larix gmelinii Rupr.). The data were based on stem analysis of 74 trees from Dailing Forest Bureau in Heilongjiang Province, Northeaster... Segmented taper equation was selected to model stem profile of Dahurian larch (Larix gmelinii Rupr.). The data were based on stem analysis of 74 trees from Dailing Forest Bureau in Heilongjiang Province, Northeastern China. Two taper equations with crown ratio and stand basal area were derived from the Max and Burkhart’s (1976) taper equation. Three taper equations were evaluated: (1) the original equation, (2) the original equation with crown ratio, and (3) the original equation with basal area. SAS NLIN and SYSNLIN procedures were used to fit taper equations. Fit statistics and cross-validation were used to evaluate the accuracy and precision of these models. Parameter estimates showed that the original equation with inclusion of crown ratio and basal area variables provided significantly different parameter estimates with lower standard errors. Overall fit statistics indicated that the root mean square error (RMSE) for diameter outside and inside bark decreased respectively by 10% and 7% in the original model with crown ratio and by 12% and 7.2% in the original model with basal area. Cross-validation further confirmed that the original equation with inclusion of crown ratio and basal area variables provided more accurate predictions at the lower section (relative heights, 10%) and upper section (relative heights, 50%) for both outside and inside bark diameters. 展开更多
关键词 basal area crown ratio Larix gmelinii nonlinear regression taper equations
下载PDF
Basal internode elongation of rice as affected by light intensity and leaf area 被引量:6
11
作者 Xuhua Zhong Kaiming Liang +5 位作者 Bilin Peng Ka Tian Xiaojuan Li Nongrong Huang Yanzhuo Liu Junfeng Pan 《The Crop Journal》 SCIE CAS CSCD 2020年第1期62-70,共9页
Short basal internodes are important for lodging resistance of rice(Oryza sativa L.).Several canopy indices affect the elongation of basal internodes,but uncertainty as to the key factors determining elongation of bas... Short basal internodes are important for lodging resistance of rice(Oryza sativa L.).Several canopy indices affect the elongation of basal internodes,but uncertainty as to the key factors determining elongation of basal internodes persists.The objectives of this study were(1)to identify key factors affecting the elongation of basal internodes and(2)to establish a quantitative relationship between basal internode length and canopy indices.An inbred rice cultivar,Yinjingruanzhan,was grown in two split-plot field experiments with three N rates(0,75,and 150 kg N ha−1 in early season and 0,90,and 180 kg N ha−1 in late season)as main plots,three seedling densities(16.7,75.0,and 187.5 seedlings m−2)as subplots,and three replications in the 2015 early and late seasons in Guangzhou,China.Light intensity at base of canopy(Lb),light quality as determined from red/far-red light ratio(R/FR),light transmission ratio(LTR),leaf area index(LAI),leaf N concentration(NLV)and final length of second internode(counted from soil surface upward)(FIL)were recorded.Higher N rate and seedling density resulted in significantly longer FIL.FIL was negatively correlated with Lb,LTR,and R/FR(P<0.01)and positively correlated with LAI(P<0.01),but not correlated with NLV(P>0.05).Stepwise linear regression analysis showed that FIL was strongly associated with Lb and LAI(R2=0.82).Heavy N application to pot-grown rice at the beginning of first internode elongation did not change FIL.We conclude that FIL is determined mainly by Lb and LAI at jointing stage.NLV has no direct effect on the elongation of basal internodes.N application indirectly affects FIL by changing LAI and light conditions in the rice canopy.Reducing LAI and improving canopy light transmission at jointing stage can shorten the basal internodes and increase the lodging resistance of rice. 展开更多
关键词 Internode elongation Leaf area index Light intensity Light quality R/FR Light transmission ratio Leaf N concentration
下载PDF
Ambient noise as the new source for urban engineering seismology and earthquake engineering: a case study from Beijing metropolitan area 被引量:8
12
作者 Lanbo Liu Qi-fu Chen +1 位作者 Weijun Wang Eric Rohrbach 《Earthquake Science》 2014年第1期89-100,共12页
In highly populated urban centers, traditional seismic survey sources can no longer be properly applied due to restrictions in modern civilian life styles. The ambient vibration noise, including both microseisms and m... In highly populated urban centers, traditional seismic survey sources can no longer be properly applied due to restrictions in modern civilian life styles. The ambient vibration noise, including both microseisms and microtremor, though are generally weak but available anywhere and anytime, can be an ideal supplementary source for conducting seismic surveys for engineering seismology and earthquake engineering. This is funda- mentally supported by advanced digital signal processing techniques for effectively extracting the useful information out from the noise. Thus, it can be essentially regarded as a passive seismic method. In this paper we first make a brief survey of the ambient vibration noise, followed by a quick summary of digital signal processing for passive seismic surveys. Then the applications of ambient noise in engi- neering seismology and earthquake engineering for urban settings are illustrated with examples from Beijing metro- politan area. For engineering seismology the example is the assessment of site effect in a large area via microtremor observations. For earthquake engineering the example is for structural characterization of a typical reinforced con- crete high-rise building using background vibration noise.By showing these examples we argue that the ambient noise can be treated as a new source that is economical, practical, and particularly valuable to engineering seis- mology and earthquake engineering projects for seismic hazard mitigation in urban areas. 展开更多
关键词 Ambient noise Resonance frequency -Ground motion amplification Seismic vulnerability ~Horizontal to vertical spectra/ratio (HVSR) ~Seismic interferometry (SI) ~ Beijing metropolitan area
下载PDF
Analysis and improving ways for water condition in winter wheat field of dryland in subhumid areas of the Loess Plateau 被引量:1
13
作者 Zhong Zhaozhan, Zhao Jubao Institute of Agrometeorology, Chinese Academy of Agricultural Sciences, Beijing 100081,China 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 1998年第3期85-94,共10页
Based on the soil moisture data from the locating experiments from 1986—1990, and using the water balance method, the water supply and demand state in the field of winter wheat, and the ways for improving water cond... Based on the soil moisture data from the locating experiments from 1986—1990, and using the water balance method, the water supply and demand state in the field of winter wheat, and the ways for improving water condition in dryland of dry subhumid area of the Loess Plateau were studied. The results suggested that a low precipitation satisfying ratio of 42.9%—58.8% appears in the growing period of winter wheat, and the yield, to a great extent depended on the water that was stored in deep soil layer in the previous rainy season. The filed trial results showed that tillage in the summer fallow period,straw cover, soil moisture regulation with adequate fertilization, crop rotation and proper cropping system could be the efficient ways for improving the water condition,and for the exploitation and utilization of natural water resources(both precipitation and soil water) in the winter wheat field of dryland. 展开更多
关键词 soil moisture water balance precipitation meet ratio dry subhumid area DRYLAND rainfed agriculture.
下载PDF
Secondary Production of Macrobenthos in Mangrove Area of Tong'an Bay,China 被引量:2
14
作者 ZHOU Xiping CAI Lizhe 《Journal of Ocean University of China》 SCIE CAS 2010年第2期151-156,共6页
Studies on secondary production lead to a better understanding of the functions of the macrobenthic ecosystem.Basedon the macrobenthic data obtained at 6 sampling stations from April 2006 to January 2007,Brey's(19... Studies on secondary production lead to a better understanding of the functions of the macrobenthic ecosystem.Basedon the macrobenthic data obtained at 6 sampling stations from April 2006 to January 2007,Brey's(1990)empirical formula wasapplied to calculate the secondary production of macrobenthos in the mangrove area of Tong'an Bay.The results showed that themean annual secondary production of macrobenthos was 13.24 gAFDWm-2-a-1.The mean secondary production in the mangrovehabitat was 12.22 gAFDWm-2-a-1,lower than that in the non-mangrove habitat,which was 15.29 gAFDWm-2-a-1.Two possible rea-sons existed for this difference.First,mollusk and crustacean,which contribute more to the secondary production,probably benefitfrom longer inundation period in the non-mangrove habitat.Second,the higher organic matter in the mangrove habitat results in hy-poxia in the bottom sediment,which may decrease the secondary production.The annual mean production-to-biomass(P/B)ratio inTong'an Bay was 1.17,with a ratio of 1.27 in the mangrove habitat and 0.96 in the non-mangrove habitat,which was coincident withthe much higher density of Limnodriloides sp.and Corophium sp.in the mangrove habitat than in the non-mangrove habitat.Themaximum secondary production and P/B ratio of macrobenthos both appeared at sampling station FL2 in April,2006(namelyApril-FL2)with values of 31.38 gAFDWm-2-a-1and 2.20,respectively.The macrobenthic secondary production in Tong'an Bay islower than those in other intertidal studies except that in Haitan Strait,the reason being the different sediment properties.The P/Bratio in Tong'an Bay was the lowest due to the high proportion of crustaceans in the macrobenthic community. 展开更多
关键词 secondary production MACROBENTHOS P/B ratio Tong'an Bay mangrove area
下载PDF
Mapping favorable groundwater potential recharge zones using a GIS-based analytical hierarchical process and probability frequency ratio model:A case study from an agro-urban region of Pakistan 被引量:3
15
作者 Arfan Arshad Zhijie Zhang +1 位作者 Wanchang Zhang Adil Dilawar 《Geoscience Frontiers》 SCIE CAS CSCD 2020年第5期1805-1819,共15页
In Punjab(Pakistan),the increasing population and expansion of land use for agriculture have severely exploited the regional groundwater resources.Intensive pumping has resulted in a rapid decline in the level of the ... In Punjab(Pakistan),the increasing population and expansion of land use for agriculture have severely exploited the regional groundwater resources.Intensive pumping has resulted in a rapid decline in the level of the water table as well as its quality.Better management practices and artificial recharge are needed for the development of sustainable groundwater resources.This study proposes a methodology to delineate favorable groundwater potential recharge zones(FPRI)by integrating maps of groundwater potential recharge index(PRI)with the DRASTIC-based groundwater vulnerability index(VI).In order to evaluate both indexes,different thematic layers corresponding to each index were overlaid in ArcGIS.In the overlay analysis,the weights(for various thematic layers)and rating values(for sub-classes)were allocated based on a review of published literature.Both were then normalized and modified using the analytical hierarchical process(AHP)and a frequency ratio model respectively.After evaluating PRI and FPRI,these maps were validated using the area under the curve(AUC)method.The PRI map indicates that 53%of the area assessed exists in very low to low recharge zones,22%in moderate,and 25%in high to excellent potential recharge zones.The VI map indicates that 38%of the area assessed exists in very low to low vulnerability,33%in moderate,and 29%in high to very high vulnerability zones.The FPRI map shows that the central region of Punjab is moderately-to-highly favorable for recharge due to its low vulnerability and high recharge potential.During the validation process,it was found that the AUC estimated with modified weights and rating values was 79%and 67%,for PRI and VI indexes,respectively.The AUC was less when evaluated using original weights and rating values taken from published literature.Maps of favorable groundwater potential recharge zones are helpful for planning and implementation of wells and hydraulic structures in this region. 展开更多
关键词 Weightage overlay Analytical hierarchical process(AHP)analysis Frequency ratio(FR) VULNERABILITY Groundwater recharge zones area under curve(AUC)
下载PDF
Effects of Geometric Configurations on the Performance of Reverse Flow Diverters in Reverse Flow Mode 被引量:1
16
作者 徐聪 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第5期856-862,共7页
The reverse flow diverter (RFD) consisting of a nozzle and a diffuser is a key component in pneumatic pulse jet pumps. We investigated the effects of suction gap and diffuser configurations on RFD performance during t... The reverse flow diverter (RFD) consisting of a nozzle and a diffuser is a key component in pneumatic pulse jet pumps. We investigated the effects of suction gap and diffuser configurations on RFD performance during the reverse flow mode. Three suction gap configurations were examined: (1) an axisymmetrical cylinder, (2) a cuboid whose bottom plane had no half-circle groove and was level with the diffuser entrance lower border, and (3) a cuboid with a half-circle groove on the bottom plane. Among them, the second one resulted in the highest RFD pumping capacity. The effect of receiver presence before the diffuser was also examined. RFD pumping efficiency was found to be enhanced in the presence of a receiver before the diffuser when the suction gap length is small and the jet outlet velocity at the nozzle exit is high enough. Based on experimental data, a dimensionless performance curve of the suction factor q versus the ratio of Euler numbers in sections out-out and 0-0 Eu out /Eu 0 was derived. This curve is insensitive to suction gap configurations. 展开更多
关键词 reverse flow diverter suction gap RECEIVER nozzle area ratio reverse flow mode
下载PDF
Hydrogeochemistry of Groundwater from Different Aquifer in Dimbhe Command Area of Ghod River, Maharashtra India
17
作者 Geeta Pillai Iftekhar A. Khan 《Journal of Water Resource and Protection》 2017年第6期656-662,共7页
The groundwater geochemistry of Dimbhe command area of Ghod River basin was evaluated based on major ions characteristic to decide its suitability for drinking, domestic use, and irrigation. Groundwater samples from d... The groundwater geochemistry of Dimbhe command area of Ghod River basin was evaluated based on major ions characteristic to decide its suitability for drinking, domestic use, and irrigation. Groundwater samples from different depth (shallow and deep) aquifer were collected and investigated for pH, electrical conductivity (EC), total dissolved solid (TDS), Ca, Mg, Na, K, Cl, SO4, CO3, HCO3, NO3, Fe, and Mn. The results show that the shallow groundwater is dominated by Ca-HCO3 and Na-HCO3 and deep aquifer by Na-HCO3 water facies. The sodium adsorption ratio (SAR) and salinity hazard indicate that the groundwater from the shallow and deep aquifer is suitable for irrigation purposes, and part of the intermediate aquifer is not suitable for crop irrigation. Groundwater from the shallow and deep aquifer is regarded as fresh water and suitable for drinking, domestic and agricultural irrigation use. 展开更多
关键词 Dimbhe COMMAND area of Ghod RIVER Hydrochemical FACIES Sodium Adsorption ratio (SAR)
下载PDF
Climate Evolution Recorded by Organic Carbon Stable I sotope since 5 kaB.P.in Poyang Lake Area, China
18
作者 Peng Hongxia Li Chang’an Shi Chaoyi Yang Chao Huang Changsheng Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074 《Journal of China University of Geosciences》 SCIE CSCD 2003年第1期25-27,共3页
Based on the data of organic carbon stable isotope ratios and magnet ic susceptibility, climate evolution in the past 5 kaB.P. in Poyang Lake plain (in Jiangxi Province) has been reconstructed. The results of the re... Based on the data of organic carbon stable isotope ratios and magnet ic susceptibility, climate evolution in the past 5 kaB.P. in Poyang Lake plain (in Jiangxi Province) has been reconstructed. The results of the research indicate that the climate evolution can be divided into nine stages in the past 5 kaB.P.. Comparisons of different regional environmental records suggest that the intens ity and the temporal spatial changes of monsoon in China mainly controlled the climate evolution. 展开更多
关键词 Poyang Lake area paleoclimate evolution organic carbon stable isoto pe ratios magnetic susceptibility.
下载PDF
Impact of Lifestyle Intervention on the Estimated Visceral Fat Area and Skeletal Muscle Mass in Men with Obesity
19
作者 Ali Madi Almajwal 《Food and Nutrition Sciences》 2018年第12期1434-1443,共10页
Background: The lifestyle modification remains the fundamental approach for the obesity treatment. The aim of this study is to demonstrate the effect of the multimodal lifestyle intervention on the estimated visceral ... Background: The lifestyle modification remains the fundamental approach for the obesity treatment. The aim of this study is to demonstrate the effect of the multimodal lifestyle intervention on the estimated visceral fat area versus changes in musculoskeletal mass in a cohort of adult men with obesity. Subjects and Methods: A retrospective cohort study in which the file of eighty-two male subjects, aged 20 - 60 years, was studied for three months. Patients had been instructed to follow a balanced-hypocaloric diet, physical activity plan and general advice for combating the unhealthy lifestyle habits through the study period. Those who succeeded to loss > 5% of their body weight were classified as weight loser (WL) group, while others as weight resistant (WR) group. The results of In Body-720 bioelectric impedance analysis were used to report the fat mass (FM), visceral fat area (VFA), skeletal muscle mass (SMM), SMM/VFA ratio, osseous mass (OM), and basal metabolic rate (BMR) before and after the study period. Anthropometric measures, glucose, and lipid profile were also analyzed. Paired t-test was used to detect the significance of change between before and after measures, independent sample t-test was used to compare WL vs. WR groups. Results: There were significant decreases in weight, FM (p 0.05) and VFA (p 0.001), in addition to a significant rise of SMM/VFA ratio (p 0.05), together with insignificant changes of osseous mass, SMM and BMR after 3 months. Additionally, total cholesterol, low-density lipoprotein, and triglycerides were significantly reduced (P 0.05). The percentages of reduction in weight, FM and VFA in WL vs. WR groups were highly significant (p 0.001), while the percentages of change in SMM, SMM/VFA ratio and BMR were significant (p 0.05). Conclusion: Lifestyle modification might be effective in production of positive changes in the body composition of patients with obesity. These changes were more significant in weight losers. 展开更多
关键词 VISCERAL Fat area SKELETAL Muscle Mass SMM/VFA ratio OBESITY InBody-720
下载PDF
Correlation between current and cross-sectional area of parallel fixed-movable dual electrodes in ESC
20
作者 Li-ting Zhao Yun-long Xiong +2 位作者 Rui Chen Zeng-rui Wang An-guo Wang 《China Foundry》 SCIE 2020年第3期245-249,共5页
Electroslag casting with parallel fixed-movable dual electrodes is a new method for achieving better quality of castings in complex mold cavities.In this work,a mathematical model,y=kx^2+(k+1)x,was established to desc... Electroslag casting with parallel fixed-movable dual electrodes is a new method for achieving better quality of castings in complex mold cavities.In this work,a mathematical model,y=kx^2+(k+1)x,was established to describe the ideal correlation between the current ratio(y)and the cross-sectional area ratio(x)of the dual electrodes,where k is the filling ratio.Investigation was conducted on the electroslag casting process with dual electrodes of various cross-sectional areas,but at a constant k value.The experimental results indicated that the ideal correlation was obtained at the stable casting stage,and the fitting results were consistent with the experimental results at certain k values.The experimental findings show that better castings can be obtained when the current ratio is greater than 1.536 and the cross-sectional area ratio is greater than 0.5. 展开更多
关键词 electroslag casting fixed-movable dual electrode current ratio cross-sectional area ratio
下载PDF
上一页 1 2 123 下一页 到第
使用帮助 返回顶部