期刊文献+
共找到39篇文章
< 1 2 >
每页显示 20 50 100
Quantized Redshift and its Significance for Recent Observation
1
作者 Arindam Mal Sarbani Palit +1 位作者 Christopher C.Fulton Sisir Roy 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第9期156-166,共11页
With the recent observational evidence in extragalactic astronomy,the interpretation of the nature of quasar redshift continues to be a research interest.Very high redshifts are being detected for extragalactic object... With the recent observational evidence in extragalactic astronomy,the interpretation of the nature of quasar redshift continues to be a research interest.Very high redshifts are being detected for extragalactic objects that are presumably very distant and young while also exhibiting properties that are characteristic of a more mature galaxy such as ours.According to Halton Arp and Geoffrey Burbidge,redshift disparities consist of an intrinsic component and are related to an evolutionary process.Karlsson observed redshift periodicity at integer multiples of0.089 in log scale and Burbidge observed redshift periodicity at integer multiples of 0.061 in linear scale.Since Singular Value Decomposition based periodicity estimation is known to be superior for noisy data sets,especially when the data contain multiple harmonics and overtones,mainly irregular in nature,we have chosen it to be our primary tool for analysis of the quasar-galaxy pair redshift data.We have observed a fundamental periodicity of0.051 with a confidence interval of 95%in linear scale with the site-available Sloan Digital Sky Survey Data Release 7(SDSS DR7)quasar-galaxy pair data set.We have independently generated quasar-galaxy pair data sets from both 2d F and SDSS and found fundamental periodicities of 0.077 and 0.089,respectively,in log scale with a confidence interval of 95%. 展开更多
关键词 galaxies:distances and redshifts (galaxies:)quasars:absorption lines cosmology:observations
下载PDF
Glacier area change (1993-2019) and its relationship to debris cover, proglacial lakes, and morphological parameters in the Chandra-Bhaga Basin, Western Himalaya, India
2
作者 VATSAL Sarvagya AZAM Mohd Farooq +5 位作者 BHARDWAJ Anshuman MANDAL Arindan BAHUGUNA Ishmohan RAMANATHAN Alagappan RAJU N.Janardhana TOMAR Sangita Singh 《Journal of Mountain Science》 SCIE CSCD 2024年第4期1287-1306,共20页
Glacier inventories serve as critical baseline data for understanding the impacts of climate change on glaciers.The present study maps the outlines of glaciers in the Chandra-Bhaga Basin(western Himalaya)for the years... Glacier inventories serve as critical baseline data for understanding the impacts of climate change on glaciers.The present study maps the outlines of glaciers in the Chandra-Bhaga Basin(western Himalaya)for the years 1993,2000,2010,and 2019 using Landsat Thematic Mapper(TM),Enhanced Thematic Mapper(ETM),and Operational Land Imager(OLI)datasets.A total of 251 glaciers,each having an area above 0.5 km^(2),were identified,which include 216 clean-ice and 35 debris-covered glaciers.Area changes are estimated for three periods:1993-2000,2000-2010,and 2010-2019.The total glacierized area was 996±62 km^(2) in 1993,which decreased to 973±70 km^(2) in 2019.The mean rate of glacier area loss was higher in the recent decade(2010-2019),at 0.036 km^(2),compared to previous decades(0.029 km^(2) in 2000-2010 and 0.025 km^(2) in 1993-2000).Supraglacial debris cover changes are also mapped over the period of 1993 and 2019.It is found that the supraglacial debris cover increased by 14.12±2.54 km^(2)(15.2%)during 1993-2019.Extensive field surveys on Chhota Shigri,Panchi II,Patsio,Hamtah,Mulkila,and Yoche Lungpa glaciers were carried out to validate the glacier outlines and supraglacial debris cover estimated using satellite datasets.Controls of various morphological parameters on retreat were also analyzed.It is observed that small,clean ice,south oriented glaciers,and glaciers with proglacial lakes are losing area at faster rates than other glaciers in the basin. 展开更多
关键词 GLACIER Area change Debris cover MORPHOLOGY Proglacial lake
下载PDF
Frameworks of Non-Orthogonal Multiple Access Techniques in Cognitive Radio Communication Systems 被引量:3
3
作者 Prabhat Thakur Alok Kumar +2 位作者 S Pandit G Singh S N Satashia 《China Communications》 SCIE CSCD 2019年第6期129-149,共21页
Recently,the increasing demand of radio spectrum for the next generation communication systems due to the explosive growth of applications appetite for bandwidths has led to the problem of spectrum scarcity.The potent... Recently,the increasing demand of radio spectrum for the next generation communication systems due to the explosive growth of applications appetite for bandwidths has led to the problem of spectrum scarcity.The potential approaches among the proposed solutions to resolve this issue are well explored cognitive radio(CR)technology and recently introduced non-orthogonal multiple access(NOMA)techniques.Both the techniques are employed for efficient spectrum utilization and assure the significant improvement in the spectral efficiency.Further,the significant improvement in spectral efficiency can be achieved by combining both the techniques.Since the CR is well-explored technique as compared to that of the NOMA in the field of communication,therefore it is worth and wise to implement this technique over the CR.In this article,we have presented the frameworks of NOMA implementation over CR as well as the feasibility of proposed frameworks.Further,the differences between proposed CR-NOMA and conventional CR frameworks are discussed.Finally,the potential issues regarding the implementation of CR-NOMA are explored. 展开更多
关键词 cognitive radio channel state information non-orthogonal MULTIPLE ACCESS power DIVISION MULTIPLE ACCESS superposition-coding successive-interference-cancellation
下载PDF
Land-use,biomass and carbon estimation in dry tropical forest of Chhattisgarh region in India using satellite remote sensing and GIS 被引量:4
4
作者 Arvind Bijalwan S.L.Swamy +2 位作者 Chandra Mohan Sharma Neeraj Kumar Sharma A.K.Tiwari 《Journal of Forestry Research》 SCIE CAS CSCD 2010年第2期161-170,I0004,I0005,共12页
A study was conducted to characterize the land use,biomass and carbon status of dry tropical forest in Raipur district of Chhattisgarh,India using satellite remote sensing data and GIS techniques in the year of 2001-2... A study was conducted to characterize the land use,biomass and carbon status of dry tropical forest in Raipur district of Chhattisgarh,India using satellite remote sensing data and GIS techniques in the year of 2001-2002.The main forest types observed in the area are Teak forest,mixed forest,degraded forest and Sal mixed forest.The aspect and slope of the sites influenced the forest vegetation types,biomass and carbon storage in the different forests.The standing volume,above ground biomass and carbon storage varied from 35.59 to 64.31 m^3·ha^-1,45.94 to 78.31 Mg·ha^-1,and 22.97 to 33.27 Mg·ha^-1,respectively among different forest types.The highest volumes,above ground biomass and carbon storage per hectare were found in the mixed forest and lowest in the degraded forest.The total standing carbon present in the entire study area was 78170.72 Mg in mixed forest,81656.91 Mg in Teak forest,7833.23 Mg in degraded forest and 7470.45 Mg in Sal mixed forest,respectively.The study shows that dry tropical forests of the studied area in Chhattisgarh are in growing stage and have strong potential for carbon sequestration. 展开更多
关键词 BIOMASS carbon storage ASPECT SLOPE
下载PDF
Inter-annual and seasonal variations in hydrological parameters and its implications on chlorophyll a distribution along the southwest coast of Bay of Bengal 被引量:2
5
作者 Shanthi R. Poornima D. +3 位作者 Raja K. Sarangi R.K. Saravanakumar A. Thangaradjou T. 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2015年第6期94-100,共7页
Seasonal and inter-annual variability of hydrological parameters and its impact on chlorophyll distribution was studied from January 2009 to December 2011 at four coastal stations along the southwest Bay of Bengal. St... Seasonal and inter-annual variability of hydrological parameters and its impact on chlorophyll distribution was studied from January 2009 to December 2011 at four coastal stations along the southwest Bay of Bengal. Statistical analysis (principal component analysis (PCA), two-way analysis of variance (ANOVA) and correlation analysis) showed the significant impact of hydrological parameters on chlorophyll distribution in the study area. The ranges of different parameters recorded were 23.8-33.8℃ (SST), 4.00-36.00 (salinity), 7.0-9.2 (pH), 4.41-8.32 mg/L (dissolved oxygen), 0.04-2.45 μmol/L (nitrite), 0.33-16.10 μmol/L (nitrate), 0.02-2.51 μmol/L (ammonia), 0.04-3.32 μmol/L (inorganic phosphate), 10.09-85.28 μmol/L (reactive silicate) and 0.04-13.8 μg/L (chlorophyll). PCA analysis carried out for different seasons found variations in the relationship between physico-chemical parameters and chlorophyll in which nitrate and chlorophyll were positively loaded at PC1 (principal component 1) during spring inter-monsoon and at PC2 (principal component 2) during other seasons. Likewise correlation analysis also showed significant positive relationship between chlorophyll and nutrients especially with nitrate (~0.734). Distribution of hydrobiological parameters between stations and distances was significantly varying as evidenced from the ANOVA results. The study found that the spatial and temporal distribution of chlorophyll was highly dependent on the availability of nutrients especially, nitrate in the southwest Bay of Bengal coastal waters. 展开更多
关键词 CHLOROPHYLL NUTRIENTS PCA NITRATE correlation analysis Bay of Bengal
下载PDF
Quality assessment of Continuous Operating Reference Stations(CORS)-GPS stations in Mexico 被引量:2
6
作者 Daniel Hernández-Andrade Rosendo Romero-Andrade +2 位作者 Gopal Sharma Manuel E.Trejo-Soto Juan L.Cabanillas-Zavala 《Geodesy and Geodynamics》 CSCD 2022年第3期275-287,共13页
The present analysis provided the quality assessment of 65 Continuous Operating Reference Stations(CORS) situated in and around Mexico using the data of about ten years(January 2010 to January 2020).To accomplish the ... The present analysis provided the quality assessment of 65 Continuous Operating Reference Stations(CORS) situated in and around Mexico using the data of about ten years(January 2010 to January 2020).To accomplish the assessment,we considered 4 quality indexes for performing the quality check,incluing the multipath effect on L1 and L2 bands,signal-to-noise ratio in both bands,cycle slips,and integrity.Meanwhile,a new reference parameter named regio nal values for Mexico(RVM) was calculated for the stations situated in Mexico.Additionally,an exhaustive analysis of the quality indicators in the worst and best cases was performed.The signal degradation was proved by a long-term time series and cru stal defo rmation analysis in GAMIT/GLOBK platform.The results showed a stro ng correlation between integrity,cycle slips and daily observations time,and the multipath effect is strong in the case of outdated systems.The study indicates that the estimated quality indexes and values could be the basis for establishing new CORS in Mexico,and the errors corrections which cannot be mitigated in the postprocessing stage would greatly help utilize the data for different scientific applications.The results were supported by deformation analysis in part of Baja California Peninsula in Mexico indicating northern and eastern velocity vector of -3.08±0.02 mm/yr,-7.85±0.02 mm/yr and-0.07±0.03 mm/yr,-9.33±0.02 mm/yr respectively at MPR1 and INEG stations. 展开更多
关键词 Multipath effect Signal-to-Noise ratio Cycle slip INTEGRITY Regional quality indicators IGS indicators
下载PDF
Lightning Nowcasting with an Algorithm of Thunderstorm Tracking Based on Lightning Location Data over the Beijing Area 被引量:2
7
作者 Abhay SRIVASTAVA Dongxia LIU +6 位作者 Chen XU Shanfeng YUAN Dongfang WANG Ogunsua BABALOLA Zhuling SUN Zhixiong CHEN Hongbo ZHANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2022年第1期178-188,共11页
A thunderstorm tracking algorithm is proposed to nowcast the possibility of lightning activity over an area of concern by using the total lightning data and neighborhood technique.The lightning radiation sources obser... A thunderstorm tracking algorithm is proposed to nowcast the possibility of lightning activity over an area of concern by using the total lightning data and neighborhood technique.The lightning radiation sources observed from the Beijing Lightning Network(BLNET)were used to obtain information about the thunderstorm cells,which are significantly valuable in real-time.The boundaries of thunderstorm cells were obtained through the neighborhood technique.After smoothing,these boundaries were used to track the movement of thunderstorms and then extrapolated to nowcast the lightning approaching in an area of concern.The algorithm can deliver creditable results prior to a thunderstorm arriving at the area of concern,with accuracies of 63%,80%,and 91%for lead times of 30,15,and 5 minutes,respectively.The real-time observations of total lightning appear to be significant for thunderstorm tracking and lightning nowcasting,as total lightning tracking could help to fill the observational gaps in radar reflectivity due to the attenuation by hills or other obstacles.The lightning data used in the algorithm performs well in tracking the active thunderstorm cells associated with lightning activities. 展开更多
关键词 neighborhood technique lightning nowcasting thunderstorm tracking lightning location data
下载PDF
Manifestation of earthquake preparation zone in the ionosphere before 2021 Sonitpur,Assam earthquake revealed by GPS-TEC data 被引量:1
8
作者 Gopal Sharma 《Geodesy and Geodynamics》 CSCD 2022年第3期230-237,共8页
Global Positioning System(GPS)Continuously Operating Reference Station(CORS)data analysis shows that the ionosphere’s electron density variability is linked to the deformation and stress accumulation in the Earth’s ... Global Positioning System(GPS)Continuously Operating Reference Station(CORS)data analysis shows that the ionosphere’s electron density variability is linked to the deformation and stress accumulation in the Earth’s crust.Anomalies in ionosphere total electron content(TEC)variability before 2021 M6.4 Sonitpur,Assam earthquake were detected using L1 and L2 GPS frequencies that showed three distinct abnormalities on April 3,9,10,2021.Pearson’s correlation coefficient(r)of TEC decreases in the CORS that lies away from the earthquake epicenter,indicating the possibilities of a positive relationship between TEC variability and earthquake epicenter.TEC concentration also decreases towards the epicenter within the earthquake preparation zone(EPZ).It is also observed that the Pearson’s correlation coefficient(r)of TEC decreases linearly near the EPZ.The study demonstrates the possibilities of determining the TEC anomalous zone in the ionosphere that coincides with the EPZ in the crustal rocks.The research indicated the possibilities of magnitude estimation of an impending earthquake based on the TEC anomalous zone in the ionosphere using closely spaced dense CORS network data. 展开更多
关键词 GPS TEC Sonitpur earthquake Ionosphere perturbation TEC anomaly Magnitude estimation
下载PDF
Observed Relationship between Surface Freshwater Flux and Salinity in The North Indian Ocean 被引量:1
9
作者 Satya PRAKASH C. MAHESH Rakesh Mohan GAIROLA 《Atmospheric and Oceanic Science Letters》 2012年第3期163-169,共7页
Using 10-year (2001 10) monthly evaporation, precipitation, and sea surface salinity (SSS) datasets, the relationship between local freshwater flux and SSS in the north Indian Ocean (NIO) is evaluated quantitatively. ... Using 10-year (2001 10) monthly evaporation, precipitation, and sea surface salinity (SSS) datasets, the relationship between local freshwater flux and SSS in the north Indian Ocean (NIO) is evaluated quantitatively. The results suggest a highly positive linear correlation between freshwater flux and SSS in the Arabian Sea (correlation coefficient, R=0.74) and the western equatorial Indian Ocean (R=0.73), whereas the linear relationships are relatively weaker in the Bay of Bengal (R=0.50) and the eastern equatorial Indian Ocean (R=0.40). Additionally, the interannual variations of freshwater flux and SSS and their mutual relationship are investigated in four sub- regions for pre-monsoon, monsoon, and post-monsoon seasons separately. The satellite retrievals of SSS from the Soil Moisture and Ocean Salinity (SMOS) and Aquarius missions can provide continuous and consistent SSS fields for a better understanding of its variability and the differences between the freshwater flux and SSS signals, which are commonly thought to be linearly related. 展开更多
关键词 EVAPORATION PRECIPITATION freshwater flux sea surface salinity North Indian Ocean
下载PDF
Development of a Web Based GIS Application for Spatial Natural Resources Information System Using Effective Open Source Software and Standards 被引量:2
10
作者 Puyam S. Singh Dibyajyoti Chutia Singuluri Sudhakar 《Journal of Geographic Information System》 2012年第3期261-266,共6页
There is growing needs for web based GIS for easy and fast dissemination, sharing, displaying and processing of spatial information which in turns helping in decision making for various natural resources based applica... There is growing needs for web based GIS for easy and fast dissemination, sharing, displaying and processing of spatial information which in turns helping in decision making for various natural resources based applications. In order to make a cost effective implementation, operation and maintenance of spatial information over the web, a cheaper yet feature rich alternative to commercial software is required which can be fulfilled by Open Source GIS software. This paper conveys an efficient approach to customize and integrate an open source web GIS system based on Mapserver as a web GIS server and PostgreSQL/PostGIS as an object oriented relational database management system (ORDBMS) for effective dissemination, sharing and management of spatial information over the internet. An open source web application tool built on top of MapScript using the PHP programming language has been used as for development of interactive user interface. The configurable Web Mapping Client Components (CWC2) tags have been added to HTML template pages in order to deploy the mapping contents to a web application. It is observed that the present system developed using open source software enables user to view, update, customized retrieval, query and analysis of natural resources information for specific needs. 展开更多
关键词 GIS MAPSERVER ORDBMS CWC2 HTML
下载PDF
The Complex Phenomenon of Glaciers of Nubra Valley, Karakorum (Ladakh), India 被引量:2
11
作者 R. K. Ganjoo M. N. Koul +1 位作者 I. M. Bahuguna Ajai   《Natural Science》 2014年第10期733-740,共8页
The Nubra valley nestled in the Karakorum Mountains of Ladakh houses about 600 glaciers of various dimensions out of which 114 glaciers were monitored in the first phase of study. The study of 114 glaciers suggests th... The Nubra valley nestled in the Karakorum Mountains of Ladakh houses about 600 glaciers of various dimensions out of which 114 glaciers were monitored in the first phase of study. The study of 114 glaciers suggests that small-sized glaciers outnumber the large-sized glaciers. Almost 52.6% of the studied glaciers are of the size less than 5 km and 31.5% of the total glaciers are between the size of 5 and 10 km. The 84 glaciers out of the 114 glaciers have been monitored on shortterm basis between the time period 1989 and 2001 whereas 30 glaciers have been monitored on long-term basis between 1969 and 2001. The monitoring of the glaciers is based on the study of Survey of India topographical sheets of 1969 and satellite imageries of time series between 1989 and 2001. The monitoring of thirty glaciers shows that 17 glaciers have lost their area between 1969 and 2001. The loss in area is from 2150 km2 in 1969 to 2026 km2 in 2001. The study of eighty- four glaciers on short-term basis between 1989 and 2001 suggests that 26 glaciers have retreated, 25 glaciers have advanced and 33 glaciers show no change during the time period. The changes in the glaciers of Nubra valley are varied and complex. 展开更多
关键词 Nubra VALLEY Indus BASIN KARAKORUM HIMALAYA LADAKH Siachen GLACIER
下载PDF
Performance analysis of cognitive radio networks using channel-prediction-probabilities and improved frame structure 被引量:1
12
作者 Prabhat Thakur Alok Kumar +2 位作者 S.Pandit G.Singh S.N.Satashia 《Digital Communications and Networks》 SCIE 2018年第4期287-295,共9页
This paper focuses on potential issues related to the random selection of a sensing channel that occurs after the prediction phase in a Cognitive Radio Network (CRN).A novel approach (Approach-l)for improved selection... This paper focuses on potential issues related to the random selection of a sensing channel that occurs after the prediction phase in a Cognitive Radio Network (CRN).A novel approach (Approach-l)for improved selection is proposed,which relies on the probabilities of channels by which they are predicted idle.Further,closed-form expressions are derived for the throughput of Cognitive Users (CUs)in the conventional and proposed approaches. In addition to this,a fimdamental approach for computing the prediction probabilities is also proposed.Moreover, a new challenging issue named "sense and stuck"was observed in the conventional approach.The proposed approach is validated by comparing the results achieved with the results of the conventional approach.However, to achieve the prediction probabilities,the pre-channel-state-information is a prerequisite,but it may be unavailable for particular scenarios;therefore,a modified selection method is introduced to avoid the sense and stuck problem.An algorithm to evaluate the throughput using the random,improved,and modified selection methods is presented with its space and time complexities.Furthermore,for additional improvement in the throughput of the CU,a new frame structure is introduced,in which the spectrum prediction and sensing periods are exploited for simultaneous transmission of data via the underlay spectrtun access technique (Approach-2).The simulated results of Approach-2 are compared with our pre-obtalned results of Approach-I,which confirm significant improvement in the throughput. 展开更多
关键词 COGNITIVE RADIO Interweave PREDICTION Spectrum accessing THROUGHPUT Underlay
下载PDF
Significance of glacio-morphological factors in glacier retreat:a case study of part of Chenab basin,Himalaya 被引量:4
13
作者 Rupal M.BRAHMBHATT I.M.BAHUGUNA +4 位作者 B.P RATHORE Anil V.KULKARNI Rajesh D.SHAH A.S.RAJAWAT Jeffrey S.KARGEL 《Journal of Mountain Science》 SCIE CSCD 2017年第1期128-141,共14页
A study has been carried out in part of Chenab basin,Himalaya to understand the relationship between glacio-morphological factors and change in glacial area. Initially change in areal extent of glaciers was derived fo... A study has been carried out in part of Chenab basin,Himalaya to understand the relationship between glacio-morphological factors and change in glacial area. Initially change in areal extent of glaciers was derived for two time frames(1962-2001/02 and 2001/02-2010/11). The study comprised of 324 glaciers for the monitoring period of 1962-2001/02 for,which 11% loss in glacial area was observed. Two hundred and thirty-eight glaciers were further monitored between 2001/02 and 2010/11. These glaciers showed an area loss of 1.1%. The annual deglaciation has been found to be higher during the period of 1962-2001/02 compared to 2001/02-2010/11. The spatial and temporal variability in deglaciation was also addressed usingglacio-morphic parameters. Area,length,percentage of debris cover,and various elevation parameters of glaciers were observed to have significant controls on relationships to the rate of glacial shrinkage. Largerarea and longer glaciers show a lower percentage of retreat than smaller and shorter ones. Moreover,glaciers located at lower altitudes and having gentle slopes show more area retreat. The results of area retreat in debris covered and debris free glaciers supports that the glaciers covered by debris retard ice melting at some extent. 158 glaciers were observed having no debris cover,and these exhibit 14% of loss in surface area. In glaciers having 40% debris cover,8% of deglaciation was observed. The glaciers located below equilibrium line altitude(ELA) have experienced 4.6% of deglaciation for the time frame 2001/02 – 2010/11 whereas it was found to be 1.1% for the glaciers occurring above ELA. However,theorientation of glaciers did not show any considerable influence on glacial change based on hypothesis. 展开更多
关键词 Glacier retreat Aspect Slope Altitude Debris cover Areal extent Climate change
下载PDF
Spatial Variability and Radiative Impact of Aerosol along the Brahmaputra River Valley in India: Results from a Campaign 被引量:1
14
作者 Shyam Sundar Kundu Arup Borgohain +2 位作者 Nilamoni Barman Meenakshi Devi P. L. N. Raju 《Journal of Environmental Protection》 2018年第4期405-430,共26页
The first ever land campaign to study the spatial variability of the aerosol characteristics along the Brahmaputra river valley (BRV) in Assam, North-Eastern India, was conducted during 2011. Measurements were made ov... The first ever land campaign to study the spatial variability of the aerosol characteristics along the Brahmaputra river valley (BRV) in Assam, North-Eastern India, was conducted during 2011. Measurements were made over 13 locations for Aerosol Optical Depth (AOD), scattering coefficient, particulate matter, black carbon (BC) concentration and meteorological parameters. The BRV is divided into three sectors longitudinally viz western sector (WS), central sector (CS), and eastern sector (ES). Significant Spatial heterogeneity in AOD and BC concentration was observed (p < 0.05) with the highest values over WS and a continual decrease from WS to ES with aerosol dominance in PM2.5 category along the entire valley. The Angstrom coefficient measured using different wavelength pairs showed spatial variability indicating dominance of fine particles over WS and coarse particles in ES with a probable bimodal distribution. The scattering and absorption coefficient shows dominance of both types of aerosol over WS than other areas. The shortwave radiative forcing was higher over the WS than CS and ES of the valley. The campaign revealed that under favorable wind conditions, the BRV is loaded with significant amount of natural and anthropogenic aerosol during local winter and is influenced by the long-range transport of aerosols from the Indo-Gangetic plain. 展开更多
关键词 Brahmaputra VALLEY AEROSOL RADIATIVE FORCING Land CAMPAIGN BLACK Carbon
下载PDF
A Geospatial Approach to Climatic Zone Specific Effective Horticultural Planning in East Khasi Hills District of Meghalaya, India 被引量:1
15
作者 Jonali Goswami Dibyajyoti Chutia S. Sudhakar 《Journal of Geographic Information System》 2012年第3期267-272,共6页
Climatic zone is one of the most important units for horticultural planning. Survival and failure of particular land use or farming system in a given region heavily relies on careful assessment of agroclimatic resourc... Climatic zone is one of the most important units for horticultural planning. Survival and failure of particular land use or farming system in a given region heavily relies on careful assessment of agroclimatic resources. Large variety of crops is being grown in Meghalaya traditionally, based on the needs and cultural practices of people without any consideration to the suitability of the climate. This study attempts to make adjustments with the climate based upon scientific knowledge to make the best use of the natural resources so as to recommend more area under horticultural crops. This has been made by identifying existing land use and appropriate land use strategies mainly for horticultural crops for each agro-climatic region. Modern Geospatial technology such as satellite Remote Sensing (RS) and Geographical Information System (GIS) and GPS have been used effectively to provide newer dimensions in identifying suitable sites for various horticultural crops and also for appropriate monitoring and management of land resources in an integrated manner with reference to agro-climatic condition. 展开更多
关键词 CLIMATIC Zone GEOSPATIAL Technology RS GIS
下载PDF
Characterization and Evaluation of Natural Resources for Land Use Diversification Planning: A Case Study in a Block of Meghalaya Using RS &GIS Technique 被引量:1
16
作者 Pratibha T. Das H. Suchitra Devi +1 位作者 S. Sudhakar Mammi Rently 《International Journal of Geosciences》 2014年第2期170-177,共8页
Characterization and evaluation of land resources of Mawryngkneng block was carried out using IRS-P6 LISS III and LISS-IV data. Five major physiographic units namely structural hills, denudational hills, plateau and i... Characterization and evaluation of land resources of Mawryngkneng block was carried out using IRS-P6 LISS III and LISS-IV data. Five major physiographic units namely structural hills, denudational hills, plateau and intermontane valley were identified. Visual interpretation of satellite data indicated that 32.2% of the total geographical area (TGA) is under dense forest followed by wastelands (28.8%), open forest (16.1%), cultivated area (13.6%), built up area (8.2%) and water body (0.9%). Ten soil series were tentatively identified and the soils belonged to 2 orders (Ultisols and Alfisols), 3 sub orders (Udult, Udalf and Humult), 6 great groups, 8 sub groups. The soils are moderately acidic, deep to very deep and texture varies from sandy clay loam to clay. The soils are very rich in organic carbon. The availability of nitrogen is medium to high and phosphorus availability is low to medium whereas potassium availability is low in the entire study area. The soils were grouped into land capability class II & III and the soils were moderately to marginally suitable for orange and marginally suitable for pine apple. An action plan with suggested land use and interventions has been prepared by using all land resource information generated under the study. The action plan includes areas for afforestation, intensive cultivation in the existing cropped areas with soil conservation measures like mulching, zero tillage etc. and orange and pine apple plantation in open scrub lands which are cultivable wastelands. This might help the farmers and the planner in better management of land resources for sustained productivity. 展开更多
关键词 LAND Resources LAND EVALUATION ALTERNATE LAND Use Remote Sensing GIS
下载PDF
Glacier Area Change over Past 50 Years to Stable Phase in Drass Valley, Ladakh Himalaya (India) 被引量:1
17
作者 M. N. Koul I. M. Bahuguna +4 位作者 Ajai A. S. Rajawat Sadiq Ali Sumit Koul 《American Journal of Climate Change》 2016年第1期88-102,共15页
Glaciers are dynamic reservoirs of constantly exchanging mass with parts of global hydrological system, process by which glaciers gain or lose snow and ice and establish a link between climate, glacier mass and glacie... Glaciers are dynamic reservoirs of constantly exchanging mass with parts of global hydrological system, process by which glaciers gain or lose snow and ice and establish a link between climate, glacier mass and glacier fluvial dynamics related directly to the behaviour of climate. Here, we report on glacier status over the past 50 years (1962-2013) on remotely-sensed volumetric changes of glaciers in Drass glacier basin, Ladakh Mountain, North-West Himalaya. Drass basin houses 150 glaciers of different dimensions predominantly (nearly 75%) by small sized glaciers. The glaciers monitored on multi-temporal satellite images of the year’s 2001, 2013 for short-term basis, and, Survey of India topographic sheets of 1965 (surveyed in 1963) on long-term basis. Machoi glacier has been selected for detailed study to assess health and fluctuation record on which observation has been made since the year 1875. The long-term monitoring (1965-2001) of 81 glaciers shows that 12.5% of glaciers have gained the area whereas 14% of large glaciers lost area 5% to 15%, and remaining 73% glaciers lost area marginally (<5%). The short-term monitoring shows that 80% glaciers do not show any change in area;even large glaciers vacated 0.64% - 2.6% area and small glaciers 1.68% - 9% glacier area. The trends in annual, seasonal and monthly maximum/minimum temperature and precipitation (snowfall and rainfall) of Drass for period 1987-2013 show that two different patterns of weather conditions: 1988-2001, cold moist winters with dry summers, and 2002-2013, a period of long winters and cool and moist summers, corroborate with transitional phase of glacier behaviour. This phenomenon has resulted in incorporating no change in area of 80% of glacier (120 glaciers) and remaining 20 percentage of glaciers show marginal loss in area. The positive balance mass for last four years (2011-2014) in benchmark Machoi glacier with cumulative specific balance +0.16 m w.e/km2/yr further indicates about the stability phase of the glaciers. 展开更多
关键词 Climate Change Stability of Himalayan Glaciers Remote Sensing GIS Glacier Mass Balance Benchmark Glacier
下载PDF
Assessment of alpine summit flora in Kashmir Himalaya and its implications for long-term monitoring of climate change impacts
18
作者 Maroof HAMID Anzar Ahmad KHUROO +2 位作者 Akhtar Hussain MALIK Rameez AHMAD Chandra Prakash SINGH 《Journal of Mountain Science》 SCIE CSCD 2020年第8期1974-1988,共15页
In an era of climate change,the availability of empirical data on alpine summit vegetation in the Himalaya is still scarce.Here we report the assessment of alpine summit flora in Gulmarg Wildlife Sanctuary,Kashmir Him... In an era of climate change,the availability of empirical data on alpine summit vegetation in the Himalaya is still scarce.Here we report the assessment of alpine summit flora in Gulmarg Wildlife Sanctuary,Kashmir Himalaya.We employed a globally standardized Multi-Summit Approach and four spatially isolated summits spanning an elevation gradient of 210 m(between 3530-3740 m a.s.l.)from natural treeline to nival zone were studied.Sampling of the summits was carried out in the year 2018 to collect floristic data together with records of soil temperature.A total of 142 vascular plant species were recorded in the sampled summits.Majority of the species were of herbaceous growth form and with perennial life span.Based on Raunkiaer’s life form,hemicryptophytes were the most dominant followed by therophytes and phanerophytes.The summit flora showed the predominance of narrow-endemic species,with broad-and non-endemics declining with elevation.A significant relationship between growth form,Raunkiaer’s life form,and the degree of endemism with elevation was observed.Both species diversity and soil temperature showed a monotonic decrease with increasing elevation.Interestingly,soil temperature clearly determined the magnitude of species diversity on the summits.Furthermore,based on floristic composition,the lowest summit had the highest dissimilarity with the rest of the summits.The present study employed globally standardized protocol to scientifically assess the patterns of plant diversity on the alpine mountain summits of Kashmir Himalaya,which in turn has wide implications towards long-term monitoring of climate change impact on alpine biodiversity in the rapidly warming Himalaya. 展开更多
关键词 Alpine ecosystem Elevation gradient ENDEMISM HIMALAYA Mountain summits
下载PDF
Asymptotic Magnitude Bode Plots of Fractional-Order Transfer Functions
19
作者 Ameya Anil Kesarkar Selvaganesan Narayanasamy 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2019年第4期1019-1026,共8页
Development of asymptotic magnitude Bode plots for integer-order transfer functions is a well-established topic in the control theory.However,construction of such plots for the fractional-order transfer functions has ... Development of asymptotic magnitude Bode plots for integer-order transfer functions is a well-established topic in the control theory.However,construction of such plots for the fractional-order transfer functions has not received much attention in the existing literature.In the present paper,we investigate in this direction and derive the procedures for sketching asymptotic magnitude Bode plots for some of the popular fractional-order controllers such as PI^α,[PI]^α,PD^β,[PD]^β,and PI^αD^β.In addition,we deduce these plots for general fractional commensurate-order transfer functions as well.As applications of this work,we illustrate 1)the analysis of the designed fractional-control loop and 2)the identification of fractional-order transfer function from a given plot. 展开更多
关键词 ASYMPTOTIC MAGNITUDE Bode commensurateorder FRACTIONAL-ORDER
下载PDF
Vascular plants distribution in relation to topography and environmental variables in alpine zone of Kedarnath Wild Life Sanctuary,West Himalaya
20
作者 CHANDRA Sudeep SINGH Ankit +2 位作者 SINGH C.P. NAUTIYAL M.C. RAWAT L.S. 《Journal of Mountain Science》 SCIE CSCD 2018年第9期1936-1949,共14页
The present study was carried out in Tungnath alpine meadows of Kedarnath Wild Life Sanctuary, Western Himalaya from subalpine to upper alpine zone. A total of four summits were selected along an altitudinal gradient ... The present study was carried out in Tungnath alpine meadows of Kedarnath Wild Life Sanctuary, Western Himalaya from subalpine to upper alpine zone. A total of four summits were selected along an altitudinal gradient and sampled for detailed vegetation analysis using multi summit approach as per Global observation research initiative in alpine environments(GLORIA). Species richness, diversity, and evenness among four summits as well as the interaction between environmental variables with plant communities were assessed. Monthly mean soil temperature was calculated using data retrieved from geo-precision temperature logger in order to identify the trend of soil temperature among different season and altitudinal gradient and its implications to plant communities. Soil samples were analyzed fromeach summit by collecting randomized composite soil samples. The indirect non-metric multidimensional scaling(NMDS) and direct canonical correspondence analysis(CCA) tools of ordination techniques to determine the linkage between plant species from various sample summits and biotic/abiotic environmental gradients were used in the present study. The results of the study demonstrated increase in species richness as soil temperature increases, the ecotone representing summits were found most warm summits followed by highest species richness. Annual soil temperature increased by 1.43°C at timberline ecotone. Whereas, at upper alpine zone the soil temperature increased by 0.810 C from year 2015 to 2016. S?rensen's similarity index was found to be increased between subalpine and upper alpine zone with increase in the presence of subalpine plant species at upper alpine zone. Both the ordination tools separate the subalpine summit and their respective vegetation from summits representingtimberline ecotone and upper alpine zone. Soil p H, altitude, soil cation exchange capacity were found as the key abiotic drivers for distribution of plant species. 展开更多
关键词 GLORIA Non-metric multidimensionalscaling (NMDS) Canonical correspondence analysis(CCA) ECOTONE West Himalaya
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部