Greenhouse gases(GHGs)from agriculture in Africa are among the world’s fastest-growing emissions,with the livestock sector as the primary contributor.However,the methods for quantifying these emissions rely on manual...Greenhouse gases(GHGs)from agriculture in Africa are among the world’s fastest-growing emissions,with the livestock sector as the primary contributor.However,the methods for quantifying these emissions rely on manual and outdated data collection and processing approaches.Therefore,there is a need to develop more accurate and efficient methods of quantifying GHGs from livestock.This research developed a remote sensing and Artificial Intelligence(AI)based approach to quantify GHG emissions from cattle in the Kisombwa Ranching Scheme in Mubende District,central Uganda.We trained a deep learning algorithm,You Only Look Once(YOLO)v4,to detect cattle from the Unmanned Aerial Vehicle(UAV)images of the study area and applied the Simple Online Real-time Tracker(SORT)algo-rithm for automated counting.Methane(CH_(4))and Nitrous Oxide(N_(2)O)emissions from manure management and enteric fermentation were estimated using the number of cattle and the Tier 1 guidelines from the Intergov-ernmental Panel on Climate Change(IPCC).The total estimated emissions were 321,121.34 kg carbon dioxide equivalent(CO_(2)eq)per year,with CH_(4) at 282,282.96 kg CO_(2)eq per year(88%)and N_(2)O at 38,838.38 kg CO_(2)eq per year(12%).Enteric fermentation contributed the highest emissions,about 99%of the total CH_(4) emissions and 87% of the total GHGs.The proposed remote sensing and AI-driven method achieved an average F1 score of 88.9%,average precision of 97%,and average recall of 82.9% on the testing set of images.Therefore,these research findings demonstrate that remote sensing and AI are a more potent and efficient approach to upscale quantifying and reporting animal population and livestock GHG emissions for sustainable agriculture and climate change mitigation.展开更多
In order to evaluate whether or not the county units′ economy in the Changsha-Zhuzhou-Xiangtan(Chang-Zhu-Tan) Urban Agglomeration was growing as expected, this study analyzed the spatial economy pattern at county-lev...In order to evaluate whether or not the county units′ economy in the Changsha-Zhuzhou-Xiangtan(Chang-Zhu-Tan) Urban Agglomeration was growing as expected, this study analyzed the spatial economy pattern at county-level by using the Exploratory Spatial Data Analysis(ESDA) method. In this process, the global Moran′s I and local Getis-Ord G*i indexes were employed to analyze indicators including per capita GDP and three industrials(i.e. primary, secondary and tertiary industry) from 2000 to 2010. The results show that: 1) the county units′ economy in the Chang-Zhu-Tan Urban Agglomeration has exhibited a strong spatial autocorrelation and an accelerated integration trend since 2008(Moran′ s I increased from 0.26 to 0.56); 2) there is a significant difference in economy development between the northern and southern county units in the Chang-Zhu-Tan Urban Agglomeration: the hotspot zone with high economic level was formed among the northern county units whereas the coldspot zone with low economic level was located in the southern areas. This difference was caused primarily by the increasingly prominent economic radiation effect of Changsha ′upheaval′; 3) town density, secondary industry, and the integration policy are the major contributors driving the evolution of the spatial economy pattern in the Chang-Zhu-Tan Urban Agglomeration.展开更多
Four data fusion methods, principle component transform (PCT), brovey transform (BT), smoothing filter-based intensity modulation(SFIM), and hue, saturation, intensity (HSI), are used to merge Landsat-7 ETM+ multispec...Four data fusion methods, principle component transform (PCT), brovey transform (BT), smoothing filter-based intensity modulation(SFIM), and hue, saturation, intensity (HSI), are used to merge Landsat-7 ETM+ multispectral bands with ETM+ panchromatic band. Each of them improves the spatial resolution effectively but distorts the original spectral signatures to some extent. SFIM model can produce optimal fusion data with respect to preservation of spectral integrity. However, it results the most blurred and noisy image if the coregistration between the multispectral and pan images is not accurate enough. The spectral integrity for all methods is preserved better if the original multispectral images are within the spectral range of ETM+ pan image.展开更多
In this study,we developed multiple hybrid machine-learning models to address parameter optimization limitations and enhance the spatial prediction of landslide susceptibility models.We created a geographic informatio...In this study,we developed multiple hybrid machine-learning models to address parameter optimization limitations and enhance the spatial prediction of landslide susceptibility models.We created a geographic information system database,and our analysis results were used to prepare a landslide inventory map containing 359 landslide events identified from Google Earth,aerial photographs,and other validated sources.A support vector regression(SVR)machine-learning model was used to divide the landslide inventory into training(70%)and testing(30%)datasets.The landslide susceptibility map was produced using 14 causative factors.We applied the established gray wolf optimization(GWO)algorithm,bat algorithm(BA),and cuckoo optimization algorithm(COA)to fine-tune the parameters of the SVR model to improve its predictive accuracy.The resultant hybrid models,SVR-GWO,SVR-BA,and SVR-COA,were validated in terms of the area under curve(AUC)and root mean square error(RMSE).The AUC values for the SVR-GWO(0.733),SVR-BA(0.724),and SVR-COA(0.738)models indicate their good prediction rates for landslide susceptibility modeling.SVR-COA had the greatest accuracy,with an RMSE of 0.21687,and SVR-BA had the least accuracy,with an RMSE of 0.23046.The three optimized hybrid models outperformed the SVR model(AUC=0.704,RMSE=0.26689),confirming the ability of metaheuristic algorithms to improve model performance.展开更多
The critical environment is one of the main insufficient to positioning. Geodetic observing systems such as the global positioning system （GPS） and the global navigation satellite systems （GNSS） are routinely used...The critical environment is one of the main insufficient to positioning. Geodetic observing systems such as the global positioning system （GPS） and the global navigation satellite systems （GNSS） are routinely used to estimate the contaminating effects by critical environment. In an effort to define the accuracy and reliability of GPS/ GNSS positioning, we investigated the data having con- taminating effects due to forestry environment. Some reliability criteria and geometric concepts were defined and then examined by them. Two sets of data were collected in open sky and closed canopy separately. The analysis of the observed data was performed using the reliability criteria and geometric concepts. The accuracy and reliability of positioning strongly depended on the canopy ratio and satellite availability. The minimum detectable error on baseline was estimated about 2.5 mm under closed canopy. The number of observable satellites and minimal detectable errors were computed for each epoch. The minimal biases on estimated baselines, bias-to-noise ratios for estimating baseline components and probability of success of the integer ambiguity solution were defined in case of forest canopy. Finally, geometric quality could be achieved using the factors of dilution of precision. Thus, the presented accuracy and reliability concepts fulfill the requirement proposed by the global geodetic observing system in forest environment.展开更多
In this study,the effect of different sampling rates(i.e.observation recording interval)on the Precise Point Positioning(PPP)solutions in terms of accuracy was investigated.For this purpose,a field test was carried ou...In this study,the effect of different sampling rates(i.e.observation recording interval)on the Precise Point Positioning(PPP)solutions in terms of accuracy was investigated.For this purpose,a field test was carried out inÇorum province,Turkey,on 11 September 2019.Within this context,a Geodetic Point(GP)was established and precisely coordinated.A static GNSS measurement was occupied on the GP for about 4-hour time at 0.10 second(s)/10 Hz measurement intervals with the Trimble R10 geodetic grade GNSS receiver.The original observation file was converted to RINEX format and then decimated into the different data sampling rates as 0.2 s,0.5 s,1 s,5 s,10 s,30 s,60 s,and 120 s.All these RINEX observation files were submitted to the Canadian Spatial Reference System-Precise Point Positioning(CSRS-PPP)online processing service the day after the data collection date by choosing both static and kinematic processing options.In this way,PPP-derived static coordinates,and the kinematic coordinates of each measurement epoch were calculated.The PPP-derived coordinates obtained from each decimated sampling intervals were compared to known coordinates of the GP for northing,easting,2D position,and height components.According to the static and kinematic processing results,high data sampling rates did not change the PPP solutions in terms of accuracy when compared to the results obtained using lower sampling rates.The results of this study imply that it was not necessary to collect GNSS data with high-rate intervals for many surveying projects requiring cm-level accuracy.展开更多
The Global Positioning System(GPS)is a GNSS constellation,but GNSS is not always GPS.GPS is one of the GNSS constellations used around the world.The GNSS constellations include GPS(US),QZSS(Japan),Beidou/BDS(China),Ga...The Global Positioning System(GPS)is a GNSS constellation,but GNSS is not always GPS.GPS is one of the GNSS constellations used around the world.The GNSS constellations include GPS(US),QZSS(Japan),Beidou/BDS(China),Galileo(EU),and GLONASS(Russia).In 1999,the European Commission(EC)proposed the European Galileo satellite navigation system for the first time.A four-phase development was proposed,including public and private sector finance.Galileo was intended for both civilian and government use,and is managed and controlled by civil authorities.Galileo is made up of 30 satellites,a number of globally distributed ground stations,and a ground control and monitoring system,all of which are extremely similar to the structure,format,and layout of GPS.In this study,we investigate GPS/GLONASS/Galileo/Beidou/IRNSS/QZSS Navigation Satellite System integration algorithm for long baselines ranging from 1500 km to 3000 km in China,Japan and Mongolia.The positioning performance with GPS/GLONASS/Galileo/BDS/IRNSS/QZSS,GPS-only,Galileo-only,GLONASS-only and BDS-only,etc.is compared in terms of the positioning accuracy.An improvement of positioning accuracy over long baselines can be found with GPS/GLONASS/Galileo/BDS/QZSS/IRNSS compared with that of GPS-only and that of BDS-only.The obtained differences of the two baselines(Topcon Magnet Tools Software(Multi-GNSS)-(CSRS-PPP(GPS/GLONASS),(Trimble-RTX(GPS/GLONASS),(AUSPOS(GPS/GLONASS))Online Processing Software)by using GPS/GLONASS/Galileo/BDS/QZSS/IRNSS signals is between 40 cm and 111.5 cm on three days.展开更多
The paper contains a brief overview of the professional activities of Professor Gottfried Konecny,Professor Emeritus at the Institute of Photogrammetry and GeoInformation,Leibniz University Hannover,Germany,and his in...The paper contains a brief overview of the professional activities of Professor Gottfried Konecny,Professor Emeritus at the Institute of Photogrammetry and GeoInformation,Leibniz University Hannover,Germany,and his influence on photogrammetry,remote sensing and geospatial information science during his time at the University of New Brunswick,Canada,and at the Leibniz University.His work can be divided into educational,scientific,application,organizational,and work in international societies.Additional activities comprised of giving courses in various languages,consultancy activities,and various other cooperations which took place in many South American countries,in Africa and Asia,for organizations such as the World Bank,United Nations,German Space Agency DLR,to name only a few.Activities in connection with international societies mainly took place during Prof.Konecny’s engagement in the Council of the International Society for Photogrammetry(ISP),renamed the International Society for Photogrammetry and Remote Sensing(ISPRS),and the European Association of Remote Sensing Laboratories(EARSeL)Bureau.He was a key figure in bringing many countries and organizations to ISPRS as Ordinary and Sustaining Members.Professor Konecny has always been aware of the importance of international cooperation at various levels,also with sister societies such as the International Cartographic Association and the United Nations-Global Geospatial Information Management(UN-GGIM).His application activities span from the photogrammetry-oriented projects he was awarded in Canada,to remote sensing topics and geospatial sciences,combined with cartography during his Hannover period.His vision and endless effort are exemplary for a person who has always been devoted to the three geosciences mentioned above.Professor Konecny is the author of a number of books,journal papers and papers presented at international and national conferences.He has been a recognized keynote speaker at many conferences throughout the world due to his vast experience.This paper describes 75 years of a man who is an expert in fields which arose during his academic life.展开更多
This article focuses on the performance analysis of both real-time and post-mission kinematic precise point positioning(PPP)in challenging marine environments.For this purpose,a real dynamic experiment lasting 6 h was...This article focuses on the performance analysis of both real-time and post-mission kinematic precise point positioning(PPP)in challenging marine environments.For this purpose,a real dynamic experiment lasting 6 h was carried out on a lake dam in?orum City of Turkey.While the kinematic test was continuing,the real-time PPP coordinates were obtained for each measurement epoch with a commercial real-time PPP(RT-PPP)service,namely the Trimble Center Point RTX.Then the post-mission PPP(PM-PPP)coordinates were calculated by using Multi-GNSS data and the Multi-GNSS Experiment(MGEX)precise products.The kinematic RT-PPP and PM-PPP results showed that the PPP coordinates were consistent with the relative solution at centimetre and decimetre level in horizontal and height components,respectively.This study implies that PPP technique is a powerful tool for highly accurate positioning in both real-time and post-mission modes,even for dynamic applications in harsh environments.展开更多
The current global or regional ionospheric models have been established for monitoring the ionospheric variations. However, the spatial and temporal resolutions are not enough to describe total electron content（TEC）...The current global or regional ionospheric models have been established for monitoring the ionospheric variations. However, the spatial and temporal resolutions are not enough to describe total electron content（TEC） variations in small scales for China. In this paper, a regional ionospheric grid model（RIGM） with high spatial-temporal resolution（0.5 0.5 and 10-min interval） in China and surrounding areas is established based on spherical harmonics expansion from dense GPS measurements provided by Crustal Movement Observation Network of China（CMONOC） and the International GNSS Service（IGS）. The correlation coefficient between the estimated TEC from GPS and the ionosonde measurements is 0.97, and the root mean square（RMS） with respect to Center for Orbit Determination in Europe（CODE） Global Ionosphere Maps（GIMs） is 4.87 TECU. In addition, the impact of different spherical harmonics orders and degrees on TEC estimations are evaluated and the degree/order 6 is better. Moreover, effective ionospheric shell heights from300 km to 700 km are further assessed and the result indicates that 550 km is the most suitable for regional ionospheric modeling in China at solar maximum.展开更多
This paper outlines a methodology to estimate monthly precipitation surfaces at 1-kin resolution for the Upper Shiyang River watershed （USRW） in northwest China. Generation of precipitation maps is based on the appl...This paper outlines a methodology to estimate monthly precipitation surfaces at 1-kin resolution for the Upper Shiyang River watershed （USRW） in northwest China. Generation of precipitation maps is based on the application of a four-variable genetic algorithm （GA） trained on 10 years of weather and ancillary data, i.e., surface air temperature, relative humidity, Digital Elevation Model-derived estimates of elevation, and time of year collected at 29 weather stations in west-central Gansu and northern Qinghai province. An observed-to-GA predicted data comparison of 10 years of precipitation collected at the 29 weather stations showed that about 84% of the variability in observed values could be explained by the trained GA, including variability in two independent datasets. Point-comparisons of observed and modeled precipitation along an elevation-rainfall gradient demonstrated near-similar spatiotemporal patterns. A precipitation surface for USRW for July, 2005, was developed with the trained GA and input surfaces of surface air temperature and relative humidity generated from Moderate Resolution Imaging Spectroradiometer sensor （MODIS） products of land surface temperature. Spatial tendencies in predicted maximum and minimum values of surface air temperature, relative humidity, and precipitation within a 2-kin radius circle around selected weather stations were in close agreement with the values measured at the weather stations.展开更多
Landslides are a frequent phenomenon on mountain Elgon, particularly in Bududa district on the SW side of this extinct shield volcano. Landslides have led to the destruction of property and loss of life we, therefore,...Landslides are a frequent phenomenon on mountain Elgon, particularly in Bududa district on the SW side of this extinct shield volcano. Landslides have led to the destruction of property and loss of life we, therefore, need to monitor them. Monitoring how landslides build-up makes it possible to timely evacuate people and build barriers to protect property against damage by landslides. Residents in Bududa have reported cracks developing in the ground and houses. These cracks continue to grow, suggesting a future catastrophic event. Such an event may resemble the 2010 landslide in Bududa, which killed approximately 450 people and destroyed much property. In order to mitigate the consequences of a new landslide as much as possible, we monitored ground motion in Bududa in eleven stations from June 2018 to June 2019. Six-hour session GPS observations were made, and deformation was determined over the observation period, June to September 2018, September to November 2018, November 2018 to February 2019 and February to June 2019. A congruency test was performed to determine how significant the deformation was. It appeared that the ground deformation differed largely at various monitored stations, ranging from 0.004 to 0.076 m, 0.001 to 0.067 m and 0 to 0.078 m in the East, North and vertical directions respectively. The values indicate that most slopes in the district are unstable, particularly in the wet seasons, which implies that future landslides pose a high risk for society.展开更多
This paper presents a lineament detection method using multi-band remote sensing images. The main objective of this work is to design an automatic image processing tool for lineament mapping from Landsat-7 ETM + satel...This paper presents a lineament detection method using multi-band remote sensing images. The main objective of this work is to design an automatic image processing tool for lineament mapping from Landsat-7 ETM + satellite data. Five procedures were involved: 1) The Principal Component Analysis;2) image enhancement using histogram equalization technique 3) directional Sobel filters of the original data;4) histogram segmentation and 5) binary image generation. The applied methodology was contributed in identifying several known large-scale faults in the Northeast of Tunisia. The statistical and spatial analyses of lineament map indicate a difference of morphological appearance of lineaments in the satellite image. Indeed, all the lineaments present a specific organization. Five groups were classified based on three orientations: NE-SW, E-W and NW-SE. The overlapping of lineament map with the geologic map confirms that these lineaments of diverse directions can be identified and recognized on the field as a fault. The identified lineaments were linked to a deep faults caused by tectonic movements in Tunisia. This study shows the performance of the satellite image processing in the analysis and mapping of the accidents in the northern Atlas.展开更多
Oasis cities are deeply affected by human activities in arid and semi-arid regions.Vegetation is an important repository in the carbon cycle of oasis urban ecosystems.The continuous expansion of urban has a disproport...Oasis cities are deeply affected by human activities in arid and semi-arid regions.Vegetation is an important repository in the carbon cycle of oasis urban ecosystems.The continuous expansion of urban has a disproportionate impact on the carbon sequestration capacity of vegetation.Till now,studies have been conducted to quantify the impact of urbanization on vegetation carbon sequestration capacity,the mechanism of such impact remains unclear and lacks systematic investigations,especially in oasis urban.Understanding the impact mechanism greatly benefits the sustainable development of oasis urban and regional carbon neutrality.To fill this knowledge gap,we design a theoretical framework to analyze the impact of urbanization on vegetation carbon sequestration capacity by isolating the direct and indirect impacts in Urumqi,China.Some results based on Landsat images indicated that the Impervious Surface Areas(ISAs)expanded by 436.98 km2 during 2000-2019.The Net Primary Productivity(NPP)calculated using the Vegetation Photosynthesis Model(VPM)was directly caused by the loss of 51.45 Gg C(1 Gg=109 g).Another important finding proved that the direct carbon loss caused by urbanization did not change the upward trend of the total carbon sequestration capacity of vegetation,but only slowed down this upward trend by 20.86%.Our results provide new insights into urban vegetation carbon sinks and contribute to a better understanding of the uncertainty of urbanization toward carbon neutrality.This study will provide scientific data support and suggestions for the sustainable development of oasis cities and the regional carbon budget.展开更多
Global Positioning System （GPS） has been widely used to estimate the total zenith tropo- spheric delay （ZTD） and precipitable water vapour （PWV） for weather prediction and at- mospheric research as a continuous ...Global Positioning System （GPS） has been widely used to estimate the total zenith tropo- spheric delay （ZTD） and precipitable water vapour （PWV） for weather prediction and at- mospheric research as a continuous and all-weather technique. However, estimations of ZTD and PWV are subject to effects of geophysical models with large uncertainties, particularly imprecise ocean tide models of inland seas in Turkey. In this paper, GPS data from Jan. 1, 2010 to Dec. 31, 2011 are processed using GAMIT/GLOBK at four co-located GPS stations （ISTN, ERZR, SAMN, and IZMI） with Radiosonde from the Turkish Met-Office together with several nearby IGS stations. Four widely used ocean tide models are adopted to evaluate their effects on GPS-estimated PWV, such as IERS recommended FES2004, NAO99b, CSR4.0 and GOT00. Five different strategies are taken without ocean tide model and with four ocean tide models, respectively, which are used to evaluate ocean tide models effects on GPS-estimated PWV through comparing with co-located Radiosonde. Results showed that ocean tide models have greatly affected the estimation of the pre- cipitable water vapour at stations near coasts. The ocean tide model FES2004 gave the best results when compared to Radiosonde with ＋2.12 mm in PWV at stations near coastline. While other ocean tides models agree each other at millimeter level in PWV. However, at inland GPS stations, ocean tide models have less effect on GPS-estimated PWV.展开更多
Registrations based on the manual placement of spherical targets are still being employed by many professionals in the industry.However,the placement of those targets usually relies solely on personal experience witho...Registrations based on the manual placement of spherical targets are still being employed by many professionals in the industry.However,the placement of those targets usually relies solely on personal experience without scientific evidence supported by numerical analysis.This paper presents a comprehensive investigation,based on Monte Carlo simulation,into determining the optimal number and positions for efficient target placement in typical scenes consisting of a pair of facades.It demonstrates new check-up statistical rules and geometrical constraints that can effectively extract and analyze massive simulations of unregistered point clouds and their corresponding registrations.More than 6×10^(7) sets of the registrations were simulated,whereas more than IOO registrations with real data were used to verify the results of simulation.The results indicated that using five spherical targets is the best choice for the registration of a large typical registration site consisting of two vertical facades and a ground,when there is only a box set of spherical targets available.As a result,the users can avoid placing extra targets to achieve insignificant improvements in registration accuracy.The results also suggest that the higher registration accuracy can be obtained when the ratio between the facade-to-target distance and target-to-scanner distance is approximately 3:2.Therefore,the targets should be placed closer to the scanner rather than in the middle between the facades and the scanner,contradicting to the traditional thought. Besides,the results reveal that the accuracy can be increased by setting the largest projected triangular area of the targets to be large.展开更多
Estimation of ground displacement in landslide susceptible regions is very critical to understanding how landslides develop. The knowledge of ground displacement rates and magnitudes helps plan for the safety of the p...Estimation of ground displacement in landslide susceptible regions is very critical to understanding how landslides develop. The knowledge of ground displacement rates and magnitudes helps plan for the safety of the people and infrastructure. The early detection of landslides in Bududa is still a challenge due to th</span><span style="font-family:Verdana;">e limited technology, hard to access, and a need for an affordable technique that can monitor a wide area continuously. In recent studies, the use of Persistent Scatterer Interferometry Synthetic Aperture Radar (PS-InSAR)</span><span style="font-family:Verdana;"> has </span><span style="font-family:Verdana;">provided vital information on landslide monitoring through the measure</span><span style="font-family:Verdana;">ment of ground displacement. In this study, Synthetic Aperture Radar (SAR) band C series of Sentinel 1-A and 1-B Satellite images were acquired between 2019 and 2020 along ascending and descending orbit paths. The Line of Sight Sight (LOS) displacement was determined for both satellite tracks, and then the LOS displacement was projected to the vertical direction. The PS-InSAR derived vertical displacement was then compared with GPS vertical displacement magnitudes over three GPS stations in the area. It was observed that vertical displacement velocity reached 20 cm/yr in Mountain Elgon. This displacement rate showed that there are points in the region that are highly unstable. The displacement velocity and magnitude in Bududa reached 6 cm/yr and 13 cm in two years. This rate and magnitude showed that Bududa is highly unstable compared with displacement velocities and magnitudes in landslide susceptible areas globally. The displacement was generally subsidence over the observation period. The vertical displacement estimated by PS-InSAR was comparable with GPS based on the estimated RMSE. The vertical displacement was highest at slopes between 32</span></span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:Verdana;">°</span></span><span style="font-family:Verdana;"> and 60</span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:Verdana;">°</span></span><span style="font-family:Verdana;"> and lowest between 0</span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:Verdana;">°</span></span><span style="font-family:Verdana;"> and 9</span><span style="font-family:""><span style="color:#4F4F4F;font-family:Verdana;">°</span><span style="font-family:Verdana;"></span></span><span style="font-family:Verdana;">. The vertical ground displacement was highly correlated with </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">rainfall that was received. The soil texture in Bududa has high clay content, with clay layering hence low drainage rates, field capacity, saturation and bulk density. It was observed that ground displacement was highly influenced by slope, rainfall and soil texture. Displacement could be estimated in three dimensions using PS-InSAR in the future if sufficient SAR images in ascending and descending tracks are made available with significantly different geometries. This would add to the knowledge of displacement patterns in the east and north directions at a large spatial scale</span><span style="font-family:Verdana;">.展开更多
Acid mine drainage is wastewater from a mine having a low pH and an elevated level of dissolved heavy metals. These metals are harmful to aquatic, animal and human life. This paper looks at the removal of copper from ...Acid mine drainage is wastewater from a mine having a low pH and an elevated level of dissolved heavy metals. These metals are harmful to aquatic, animal and human life. This paper looks at the removal of copper from acid mine drainage using ion exchange to less than 1 mg/l. A weak acidic cation resin was used. Spectrophotometric determination of copper with sodium diethyldithiocarbamate was used to determine the copper concentrations in the treated water. Using regression analysis, the experimental results gave a correlation coefficient of 0.977 and a coefficient of determination of 99.5%. Results indicated that the higher the flows rate the shorter the period after which the copper concentration in the treated water reaches 1 mg/l. At pH 3.85 and 5.09, the resin performed better and at pH above 6.62 and between pH 3.0 and below the resin’s does not perform well. The higher the resin height the greater is the resin exchange capacity and the longer it takes for the copper concentration to reach 1 mg/l in the treated water. The higher the wastewater copper concentration the shorter the time it takes the resin to reach 1 mg/l. The results for this experiment indicated that acid mine drainage can be treated well by ion exchange resins, but it is also very important to establish suitable operating conditions.展开更多
Location Based Navigation System (LBNS) is a specific Location Based Service (LBS) purely for navigational purpose. These systems resolve position of a user by using GNSS/GPS positioning technologies, to which supplem...Location Based Navigation System (LBNS) is a specific Location Based Service (LBS) purely for navigational purpose. These systems resolve position of a user by using GNSS/GPS positioning technologies, to which supplementary information on goods and services are tagged. The navigation services have become popular and can be installed on mobile phones to provide route information, location of points of interest and user’s current location. LBS has continued to face challenges which include “communication” process towards user reference. Location Based Service System conveys suitable information through a mobile device for effective decision making and reaction within a given time span. This research was geared at understanding the state of LBS technology acceptance and adoption by users in Nairobi Kenya. To do this a quantitative study was carried out through a questionnaire, to investigate mobile phone users’ response on awareness and use of LBS technology. Testing the growth of this technology in this region compared to predictions in previous studies using Technology Acceptance Model (TAM), it is evident that many users may be aware of GPS functionality in mobile phones but are certainly yet to fully embrace the technology as they rarely use it. This points to some underlying challenges towards this technology within this part of the World, thereby recommending for deliberate monitoring and evaluation of LBS technology for sustenance growth based on user satisfaction and acceptance for improved usability.展开更多
Digital elevation model （DEM） is the most popular product for three-dimensional （3D） digital representation of bare Earth surface and can be produced by many techniques with different characteristics and ground sa...Digital elevation model （DEM） is the most popular product for three-dimensional （3D） digital representation of bare Earth surface and can be produced by many techniques with different characteristics and ground sampling distances （GSD）. Space-borne opti- cal and synthetic aperture radar （SAR） imaging are two of the most preferred and modern techniques for DEM generation. Using them, global DEMs that cover almost entire Earth are produced with low cost and time saving processing. In this study, we aimed to assess the Satellite pour robservation de la Terre-5 （SPOT-5）, High Resolution Stereoscopic （HRS）, the Advanced Space-borne Thermal Emission and Reflection Radiometer （ASTER）, and the Shuttle Radar Topography Mission （SRTM） C-band global DEMs, produced with space-borne optical and SAR imaging. For the assessment, a reference DEM derived from 1 ： 1000 scaled digital photogrammetric maps was used. The study is performed in 100 km2 study area in Istanbul including various land classes such as open land, forest, built-up land, scrub and rough terrain obtained from Landsat data. The analyses were realized considering three vertical accuracy types as fundamental, supplemental, and consolidated, defined by national digital elevation program （NDEP） of USA. The results showed that, vertical accuracy of SRTM C-band DEM is better than optical models in all three accuracy types despite having the largest grid spacing. The result of SPOT-5 HRS DEM is very close by SRTM and superior in comparison with ASTER models.展开更多
基金funded by the Regional Universities Forum for Ca-pacity Building in Agriculture(RUFORUM)and the Global Research Alliance on Agricultural Greenhouse Gases(GRA)under project ID:RU/2020/GRG/06.
文摘Greenhouse gases(GHGs)from agriculture in Africa are among the world’s fastest-growing emissions,with the livestock sector as the primary contributor.However,the methods for quantifying these emissions rely on manual and outdated data collection and processing approaches.Therefore,there is a need to develop more accurate and efficient methods of quantifying GHGs from livestock.This research developed a remote sensing and Artificial Intelligence(AI)based approach to quantify GHG emissions from cattle in the Kisombwa Ranching Scheme in Mubende District,central Uganda.We trained a deep learning algorithm,You Only Look Once(YOLO)v4,to detect cattle from the Unmanned Aerial Vehicle(UAV)images of the study area and applied the Simple Online Real-time Tracker(SORT)algo-rithm for automated counting.Methane(CH_(4))and Nitrous Oxide(N_(2)O)emissions from manure management and enteric fermentation were estimated using the number of cattle and the Tier 1 guidelines from the Intergov-ernmental Panel on Climate Change(IPCC).The total estimated emissions were 321,121.34 kg carbon dioxide equivalent(CO_(2)eq)per year,with CH_(4) at 282,282.96 kg CO_(2)eq per year(88%)and N_(2)O at 38,838.38 kg CO_(2)eq per year(12%).Enteric fermentation contributed the highest emissions,about 99%of the total CH_(4) emissions and 87% of the total GHGs.The proposed remote sensing and AI-driven method achieved an average F1 score of 88.9%,average precision of 97%,and average recall of 82.9% on the testing set of images.Therefore,these research findings demonstrate that remote sensing and AI are a more potent and efficient approach to upscale quantifying and reporting animal population and livestock GHG emissions for sustainable agriculture and climate change mitigation.
基金Under the auspices of National Natural Science Foundation of China(No.41201384)Hunan Provincial Natural Science Foundation(No.12JJ3034)State Key Laboratory of Resources and Environmental Information System,Nieying Talent Program of Central South University(No.7601110176)
文摘In order to evaluate whether or not the county units′ economy in the Changsha-Zhuzhou-Xiangtan(Chang-Zhu-Tan) Urban Agglomeration was growing as expected, this study analyzed the spatial economy pattern at county-level by using the Exploratory Spatial Data Analysis(ESDA) method. In this process, the global Moran′s I and local Getis-Ord G*i indexes were employed to analyze indicators including per capita GDP and three industrials(i.e. primary, secondary and tertiary industry) from 2000 to 2010. The results show that: 1) the county units′ economy in the Chang-Zhu-Tan Urban Agglomeration has exhibited a strong spatial autocorrelation and an accelerated integration trend since 2008(Moran′ s I increased from 0.26 to 0.56); 2) there is a significant difference in economy development between the northern and southern county units in the Chang-Zhu-Tan Urban Agglomeration: the hotspot zone with high economic level was formed among the northern county units whereas the coldspot zone with low economic level was located in the southern areas. This difference was caused primarily by the increasingly prominent economic radiation effect of Changsha ′upheaval′; 3) town density, secondary industry, and the integration policy are the major contributors driving the evolution of the spatial economy pattern in the Chang-Zhu-Tan Urban Agglomeration.
文摘Four data fusion methods, principle component transform (PCT), brovey transform (BT), smoothing filter-based intensity modulation(SFIM), and hue, saturation, intensity (HSI), are used to merge Landsat-7 ETM+ multispectral bands with ETM+ panchromatic band. Each of them improves the spatial resolution effectively but distorts the original spectral signatures to some extent. SFIM model can produce optimal fusion data with respect to preservation of spectral integrity. However, it results the most blurred and noisy image if the coregistration between the multispectral and pan images is not accurate enough. The spectral integrity for all methods is preserved better if the original multispectral images are within the spectral range of ETM+ pan image.
基金supported by the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources(KIGAM)Project of Environmental Business Big Data Platform and Center Construction funded by the Ministry of Science and ICT。
文摘In this study,we developed multiple hybrid machine-learning models to address parameter optimization limitations and enhance the spatial prediction of landslide susceptibility models.We created a geographic information system database,and our analysis results were used to prepare a landslide inventory map containing 359 landslide events identified from Google Earth,aerial photographs,and other validated sources.A support vector regression(SVR)machine-learning model was used to divide the landslide inventory into training(70%)and testing(30%)datasets.The landslide susceptibility map was produced using 14 causative factors.We applied the established gray wolf optimization(GWO)algorithm,bat algorithm(BA),and cuckoo optimization algorithm(COA)to fine-tune the parameters of the SVR model to improve its predictive accuracy.The resultant hybrid models,SVR-GWO,SVR-BA,and SVR-COA,were validated in terms of the area under curve(AUC)and root mean square error(RMSE).The AUC values for the SVR-GWO(0.733),SVR-BA(0.724),and SVR-COA(0.738)models indicate their good prediction rates for landslide susceptibility modeling.SVR-COA had the greatest accuracy,with an RMSE of 0.21687,and SVR-BA had the least accuracy,with an RMSE of 0.23046.The three optimized hybrid models outperformed the SVR model(AUC=0.704,RMSE=0.26689),confirming the ability of metaheuristic algorithms to improve model performance.
文摘The critical environment is one of the main insufficient to positioning. Geodetic observing systems such as the global positioning system （GPS） and the global navigation satellite systems （GNSS） are routinely used to estimate the contaminating effects by critical environment. In an effort to define the accuracy and reliability of GPS/ GNSS positioning, we investigated the data having con- taminating effects due to forestry environment. Some reliability criteria and geometric concepts were defined and then examined by them. Two sets of data were collected in open sky and closed canopy separately. The analysis of the observed data was performed using the reliability criteria and geometric concepts. The accuracy and reliability of positioning strongly depended on the canopy ratio and satellite availability. The minimum detectable error on baseline was estimated about 2.5 mm under closed canopy. The number of observable satellites and minimal detectable errors were computed for each epoch. The minimal biases on estimated baselines, bias-to-noise ratios for estimating baseline components and probability of success of the integer ambiguity solution were defined in case of forest canopy. Finally, geometric quality could be achieved using the factors of dilution of precision. Thus, the presented accuracy and reliability concepts fulfill the requirement proposed by the global geodetic observing system in forest environment.
文摘In this study,the effect of different sampling rates(i.e.observation recording interval)on the Precise Point Positioning(PPP)solutions in terms of accuracy was investigated.For this purpose,a field test was carried out inÇorum province,Turkey,on 11 September 2019.Within this context,a Geodetic Point(GP)was established and precisely coordinated.A static GNSS measurement was occupied on the GP for about 4-hour time at 0.10 second(s)/10 Hz measurement intervals with the Trimble R10 geodetic grade GNSS receiver.The original observation file was converted to RINEX format and then decimated into the different data sampling rates as 0.2 s,0.5 s,1 s,5 s,10 s,30 s,60 s,and 120 s.All these RINEX observation files were submitted to the Canadian Spatial Reference System-Precise Point Positioning(CSRS-PPP)online processing service the day after the data collection date by choosing both static and kinematic processing options.In this way,PPP-derived static coordinates,and the kinematic coordinates of each measurement epoch were calculated.The PPP-derived coordinates obtained from each decimated sampling intervals were compared to known coordinates of the GP for northing,easting,2D position,and height components.According to the static and kinematic processing results,high data sampling rates did not change the PPP solutions in terms of accuracy when compared to the results obtained using lower sampling rates.The results of this study imply that it was not necessary to collect GNSS data with high-rate intervals for many surveying projects requiring cm-level accuracy.
文摘The Global Positioning System(GPS)is a GNSS constellation,but GNSS is not always GPS.GPS is one of the GNSS constellations used around the world.The GNSS constellations include GPS(US),QZSS(Japan),Beidou/BDS(China),Galileo(EU),and GLONASS(Russia).In 1999,the European Commission(EC)proposed the European Galileo satellite navigation system for the first time.A four-phase development was proposed,including public and private sector finance.Galileo was intended for both civilian and government use,and is managed and controlled by civil authorities.Galileo is made up of 30 satellites,a number of globally distributed ground stations,and a ground control and monitoring system,all of which are extremely similar to the structure,format,and layout of GPS.In this study,we investigate GPS/GLONASS/Galileo/Beidou/IRNSS/QZSS Navigation Satellite System integration algorithm for long baselines ranging from 1500 km to 3000 km in China,Japan and Mongolia.The positioning performance with GPS/GLONASS/Galileo/BDS/IRNSS/QZSS,GPS-only,Galileo-only,GLONASS-only and BDS-only,etc.is compared in terms of the positioning accuracy.An improvement of positioning accuracy over long baselines can be found with GPS/GLONASS/Galileo/BDS/QZSS/IRNSS compared with that of GPS-only and that of BDS-only.The obtained differences of the two baselines(Topcon Magnet Tools Software(Multi-GNSS)-(CSRS-PPP(GPS/GLONASS),(Trimble-RTX(GPS/GLONASS),(AUSPOS(GPS/GLONASS))Online Processing Software)by using GPS/GLONASS/Galileo/BDS/QZSS/IRNSS signals is between 40 cm and 111.5 cm on three days.
基金This work is supported by Development of research oriented study programs(Ph.D.ESF)grant No CZ.02.2.69/0.0/0.0/16_018/0002679 financed by the Ministry of Education,Youth and Sports,Science,Research,Education.
文摘The paper contains a brief overview of the professional activities of Professor Gottfried Konecny,Professor Emeritus at the Institute of Photogrammetry and GeoInformation,Leibniz University Hannover,Germany,and his influence on photogrammetry,remote sensing and geospatial information science during his time at the University of New Brunswick,Canada,and at the Leibniz University.His work can be divided into educational,scientific,application,organizational,and work in international societies.Additional activities comprised of giving courses in various languages,consultancy activities,and various other cooperations which took place in many South American countries,in Africa and Asia,for organizations such as the World Bank,United Nations,German Space Agency DLR,to name only a few.Activities in connection with international societies mainly took place during Prof.Konecny’s engagement in the Council of the International Society for Photogrammetry(ISP),renamed the International Society for Photogrammetry and Remote Sensing(ISPRS),and the European Association of Remote Sensing Laboratories(EARSeL)Bureau.He was a key figure in bringing many countries and organizations to ISPRS as Ordinary and Sustaining Members.Professor Konecny has always been aware of the importance of international cooperation at various levels,also with sister societies such as the International Cartographic Association and the United Nations-Global Geospatial Information Management(UN-GGIM).His application activities span from the photogrammetry-oriented projects he was awarded in Canada,to remote sensing topics and geospatial sciences,combined with cartography during his Hannover period.His vision and endless effort are exemplary for a person who has always been devoted to the three geosciences mentioned above.Professor Konecny is the author of a number of books,journal papers and papers presented at international and national conferences.He has been a recognized keynote speaker at many conferences throughout the world due to his vast experience.This paper describes 75 years of a man who is an expert in fields which arose during his academic life.
文摘This article focuses on the performance analysis of both real-time and post-mission kinematic precise point positioning(PPP)in challenging marine environments.For this purpose,a real dynamic experiment lasting 6 h was carried out on a lake dam in?orum City of Turkey.While the kinematic test was continuing,the real-time PPP coordinates were obtained for each measurement epoch with a commercial real-time PPP(RT-PPP)service,namely the Trimble Center Point RTX.Then the post-mission PPP(PM-PPP)coordinates were calculated by using Multi-GNSS data and the Multi-GNSS Experiment(MGEX)precise products.The kinematic RT-PPP and PM-PPP results showed that the PPP coordinates were consistent with the relative solution at centimetre and decimetre level in horizontal and height components,respectively.This study implies that PPP technique is a powerful tool for highly accurate positioning in both real-time and post-mission modes,even for dynamic applications in harsh environments.
基金supported by the National Natural Science Foundation of China (NSFC) Project (11573052)Shanghai Science and Technology Commission Project (12DZ2273300)Key Laboratory of Planetary Sciences, Chinese Academy of Sciences
文摘The current global or regional ionospheric models have been established for monitoring the ionospheric variations. However, the spatial and temporal resolutions are not enough to describe total electron content（TEC） variations in small scales for China. In this paper, a regional ionospheric grid model（RIGM） with high spatial-temporal resolution（0.5 0.5 and 10-min interval） in China and surrounding areas is established based on spherical harmonics expansion from dense GPS measurements provided by Crustal Movement Observation Network of China（CMONOC） and the International GNSS Service（IGS）. The correlation coefficient between the estimated TEC from GPS and the ionosonde measurements is 0.97, and the root mean square（RMS） with respect to Center for Orbit Determination in Europe（CODE） Global Ionosphere Maps（GIMs） is 4.87 TECU. In addition, the impact of different spherical harmonics orders and degrees on TEC estimations are evaluated and the degree/order 6 is better. Moreover, effective ionospheric shell heights from300 km to 700 km are further assessed and the result indicates that 550 km is the most suitable for regional ionospheric modeling in China at solar maximum.
基金funded by the Chinese Meteorological Administration (CMA),the Gansu Provincial Meteorological Bureau (GMB),under the direction of the Lanzhou Regional Climate Centre(Natural Science Foundation of China under Grant No.40830957)the Faculty of Forestry and Environmental Management,University of New Brunswick
文摘This paper outlines a methodology to estimate monthly precipitation surfaces at 1-kin resolution for the Upper Shiyang River watershed （USRW） in northwest China. Generation of precipitation maps is based on the application of a four-variable genetic algorithm （GA） trained on 10 years of weather and ancillary data, i.e., surface air temperature, relative humidity, Digital Elevation Model-derived estimates of elevation, and time of year collected at 29 weather stations in west-central Gansu and northern Qinghai province. An observed-to-GA predicted data comparison of 10 years of precipitation collected at the 29 weather stations showed that about 84% of the variability in observed values could be explained by the trained GA, including variability in two independent datasets. Point-comparisons of observed and modeled precipitation along an elevation-rainfall gradient demonstrated near-similar spatiotemporal patterns. A precipitation surface for USRW for July, 2005, was developed with the trained GA and input surfaces of surface air temperature and relative humidity generated from Moderate Resolution Imaging Spectroradiometer sensor （MODIS） products of land surface temperature. Spatial tendencies in predicted maximum and minimum values of surface air temperature, relative humidity, and precipitation within a 2-kin radius circle around selected weather stations were in close agreement with the values measured at the weather stations.
文摘Landslides are a frequent phenomenon on mountain Elgon, particularly in Bududa district on the SW side of this extinct shield volcano. Landslides have led to the destruction of property and loss of life we, therefore, need to monitor them. Monitoring how landslides build-up makes it possible to timely evacuate people and build barriers to protect property against damage by landslides. Residents in Bududa have reported cracks developing in the ground and houses. These cracks continue to grow, suggesting a future catastrophic event. Such an event may resemble the 2010 landslide in Bududa, which killed approximately 450 people and destroyed much property. In order to mitigate the consequences of a new landslide as much as possible, we monitored ground motion in Bududa in eleven stations from June 2018 to June 2019. Six-hour session GPS observations were made, and deformation was determined over the observation period, June to September 2018, September to November 2018, November 2018 to February 2019 and February to June 2019. A congruency test was performed to determine how significant the deformation was. It appeared that the ground deformation differed largely at various monitored stations, ranging from 0.004 to 0.076 m, 0.001 to 0.067 m and 0 to 0.078 m in the East, North and vertical directions respectively. The values indicate that most slopes in the district are unstable, particularly in the wet seasons, which implies that future landslides pose a high risk for society.
文摘This paper presents a lineament detection method using multi-band remote sensing images. The main objective of this work is to design an automatic image processing tool for lineament mapping from Landsat-7 ETM + satellite data. Five procedures were involved: 1) The Principal Component Analysis;2) image enhancement using histogram equalization technique 3) directional Sobel filters of the original data;4) histogram segmentation and 5) binary image generation. The applied methodology was contributed in identifying several known large-scale faults in the Northeast of Tunisia. The statistical and spatial analyses of lineament map indicate a difference of morphological appearance of lineaments in the satellite image. Indeed, all the lineaments present a specific organization. Five groups were classified based on three orientations: NE-SW, E-W and NW-SE. The overlapping of lineament map with the geologic map confirms that these lineaments of diverse directions can be identified and recognized on the field as a fault. The identified lineaments were linked to a deep faults caused by tectonic movements in Tunisia. This study shows the performance of the satellite image processing in the analysis and mapping of the accidents in the northern Atlas.
基金supported by the National Natural Science Foundation of China[grant numbers 42090012,41771452,41771454]the National Key Research and Development Program of China[grant number 2018YFB0505401]+2 种基金03 special research and 5G project of Jiangxi Province in China[grant number 20212ABC03A09]Zhuhai industry university research cooperation project of China[grant number ZH22017001210098PWC]Natural Science Foundation of Sichuan[grant number 2022NSFCSC1124].
文摘Oasis cities are deeply affected by human activities in arid and semi-arid regions.Vegetation is an important repository in the carbon cycle of oasis urban ecosystems.The continuous expansion of urban has a disproportionate impact on the carbon sequestration capacity of vegetation.Till now,studies have been conducted to quantify the impact of urbanization on vegetation carbon sequestration capacity,the mechanism of such impact remains unclear and lacks systematic investigations,especially in oasis urban.Understanding the impact mechanism greatly benefits the sustainable development of oasis urban and regional carbon neutrality.To fill this knowledge gap,we design a theoretical framework to analyze the impact of urbanization on vegetation carbon sequestration capacity by isolating the direct and indirect impacts in Urumqi,China.Some results based on Landsat images indicated that the Impervious Surface Areas(ISAs)expanded by 436.98 km2 during 2000-2019.The Net Primary Productivity(NPP)calculated using the Vegetation Photosynthesis Model(VPM)was directly caused by the loss of 51.45 Gg C(1 Gg=109 g).Another important finding proved that the direct carbon loss caused by urbanization did not change the upward trend of the total carbon sequestration capacity of vegetation,but only slowed down this upward trend by 20.86%.Our results provide new insights into urban vegetation carbon sinks and contribute to a better understanding of the uncertainty of urbanization toward carbon neutrality.This study will provide scientific data support and suggestions for the sustainable development of oasis cities and the regional carbon budget.
文摘Global Positioning System （GPS） has been widely used to estimate the total zenith tropo- spheric delay （ZTD） and precipitable water vapour （PWV） for weather prediction and at- mospheric research as a continuous and all-weather technique. However, estimations of ZTD and PWV are subject to effects of geophysical models with large uncertainties, particularly imprecise ocean tide models of inland seas in Turkey. In this paper, GPS data from Jan. 1, 2010 to Dec. 31, 2011 are processed using GAMIT/GLOBK at four co-located GPS stations （ISTN, ERZR, SAMN, and IZMI） with Radiosonde from the Turkish Met-Office together with several nearby IGS stations. Four widely used ocean tide models are adopted to evaluate their effects on GPS-estimated PWV, such as IERS recommended FES2004, NAO99b, CSR4.0 and GOT00. Five different strategies are taken without ocean tide model and with four ocean tide models, respectively, which are used to evaluate ocean tide models effects on GPS-estimated PWV through comparing with co-located Radiosonde. Results showed that ocean tide models have greatly affected the estimation of the pre- cipitable water vapour at stations near coasts. The ocean tide model FES2004 gave the best results when compared to Radiosonde with ＋2.12 mm in PWV at stations near coastline. While other ocean tides models agree each other at millimeter level in PWV. However, at inland GPS stations, ocean tide models have less effect on GPS-estimated PWV.
基金Key Research and Development Program of Guangdong Province (No.2020B0101130009)
文摘Registrations based on the manual placement of spherical targets are still being employed by many professionals in the industry.However,the placement of those targets usually relies solely on personal experience without scientific evidence supported by numerical analysis.This paper presents a comprehensive investigation,based on Monte Carlo simulation,into determining the optimal number and positions for efficient target placement in typical scenes consisting of a pair of facades.It demonstrates new check-up statistical rules and geometrical constraints that can effectively extract and analyze massive simulations of unregistered point clouds and their corresponding registrations.More than 6×10^(7) sets of the registrations were simulated,whereas more than IOO registrations with real data were used to verify the results of simulation.The results indicated that using five spherical targets is the best choice for the registration of a large typical registration site consisting of two vertical facades and a ground,when there is only a box set of spherical targets available.As a result,the users can avoid placing extra targets to achieve insignificant improvements in registration accuracy.The results also suggest that the higher registration accuracy can be obtained when the ratio between the facade-to-target distance and target-to-scanner distance is approximately 3:2.Therefore,the targets should be placed closer to the scanner rather than in the middle between the facades and the scanner,contradicting to the traditional thought. Besides,the results reveal that the accuracy can be increased by setting the largest projected triangular area of the targets to be large.
文摘Estimation of ground displacement in landslide susceptible regions is very critical to understanding how landslides develop. The knowledge of ground displacement rates and magnitudes helps plan for the safety of the people and infrastructure. The early detection of landslides in Bududa is still a challenge due to th</span><span style="font-family:Verdana;">e limited technology, hard to access, and a need for an affordable technique that can monitor a wide area continuously. In recent studies, the use of Persistent Scatterer Interferometry Synthetic Aperture Radar (PS-InSAR)</span><span style="font-family:Verdana;"> has </span><span style="font-family:Verdana;">provided vital information on landslide monitoring through the measure</span><span style="font-family:Verdana;">ment of ground displacement. In this study, Synthetic Aperture Radar (SAR) band C series of Sentinel 1-A and 1-B Satellite images were acquired between 2019 and 2020 along ascending and descending orbit paths. The Line of Sight Sight (LOS) displacement was determined for both satellite tracks, and then the LOS displacement was projected to the vertical direction. The PS-InSAR derived vertical displacement was then compared with GPS vertical displacement magnitudes over three GPS stations in the area. It was observed that vertical displacement velocity reached 20 cm/yr in Mountain Elgon. This displacement rate showed that there are points in the region that are highly unstable. The displacement velocity and magnitude in Bududa reached 6 cm/yr and 13 cm in two years. This rate and magnitude showed that Bududa is highly unstable compared with displacement velocities and magnitudes in landslide susceptible areas globally. The displacement was generally subsidence over the observation period. The vertical displacement estimated by PS-InSAR was comparable with GPS based on the estimated RMSE. The vertical displacement was highest at slopes between 32</span></span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:Verdana;">°</span></span><span style="font-family:Verdana;"> and 60</span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:Verdana;">°</span></span><span style="font-family:Verdana;"> and lowest between 0</span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:Verdana;">°</span></span><span style="font-family:Verdana;"> and 9</span><span style="font-family:""><span style="color:#4F4F4F;font-family:Verdana;">°</span><span style="font-family:Verdana;"></span></span><span style="font-family:Verdana;">. The vertical ground displacement was highly correlated with </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">rainfall that was received. The soil texture in Bududa has high clay content, with clay layering hence low drainage rates, field capacity, saturation and bulk density. It was observed that ground displacement was highly influenced by slope, rainfall and soil texture. Displacement could be estimated in three dimensions using PS-InSAR in the future if sufficient SAR images in ascending and descending tracks are made available with significantly different geometries. This would add to the knowledge of displacement patterns in the east and north directions at a large spatial scale</span><span style="font-family:Verdana;">.
文摘Acid mine drainage is wastewater from a mine having a low pH and an elevated level of dissolved heavy metals. These metals are harmful to aquatic, animal and human life. This paper looks at the removal of copper from acid mine drainage using ion exchange to less than 1 mg/l. A weak acidic cation resin was used. Spectrophotometric determination of copper with sodium diethyldithiocarbamate was used to determine the copper concentrations in the treated water. Using regression analysis, the experimental results gave a correlation coefficient of 0.977 and a coefficient of determination of 99.5%. Results indicated that the higher the flows rate the shorter the period after which the copper concentration in the treated water reaches 1 mg/l. At pH 3.85 and 5.09, the resin performed better and at pH above 6.62 and between pH 3.0 and below the resin’s does not perform well. The higher the resin height the greater is the resin exchange capacity and the longer it takes for the copper concentration to reach 1 mg/l in the treated water. The higher the wastewater copper concentration the shorter the time it takes the resin to reach 1 mg/l. The results for this experiment indicated that acid mine drainage can be treated well by ion exchange resins, but it is also very important to establish suitable operating conditions.
文摘Location Based Navigation System (LBNS) is a specific Location Based Service (LBS) purely for navigational purpose. These systems resolve position of a user by using GNSS/GPS positioning technologies, to which supplementary information on goods and services are tagged. The navigation services have become popular and can be installed on mobile phones to provide route information, location of points of interest and user’s current location. LBS has continued to face challenges which include “communication” process towards user reference. Location Based Service System conveys suitable information through a mobile device for effective decision making and reaction within a given time span. This research was geared at understanding the state of LBS technology acceptance and adoption by users in Nairobi Kenya. To do this a quantitative study was carried out through a questionnaire, to investigate mobile phone users’ response on awareness and use of LBS technology. Testing the growth of this technology in this region compared to predictions in previous studies using Technology Acceptance Model (TAM), it is evident that many users may be aware of GPS functionality in mobile phones but are certainly yet to fully embrace the technology as they rarely use it. This points to some underlying challenges towards this technology within this part of the World, thereby recommending for deliberate monitoring and evaluation of LBS technology for sustenance growth based on user satisfaction and acceptance for improved usability.
基金Under the auspices of Scientific Research Project Coordinatorship of Yildiz Technical University,Turkey(No.20100503KAP01)
文摘Digital elevation model （DEM） is the most popular product for three-dimensional （3D） digital representation of bare Earth surface and can be produced by many techniques with different characteristics and ground sampling distances （GSD）. Space-borne opti- cal and synthetic aperture radar （SAR） imaging are two of the most preferred and modern techniques for DEM generation. Using them, global DEMs that cover almost entire Earth are produced with low cost and time saving processing. In this study, we aimed to assess the Satellite pour robservation de la Terre-5 （SPOT-5）, High Resolution Stereoscopic （HRS）, the Advanced Space-borne Thermal Emission and Reflection Radiometer （ASTER）, and the Shuttle Radar Topography Mission （SRTM） C-band global DEMs, produced with space-borne optical and SAR imaging. For the assessment, a reference DEM derived from 1 ： 1000 scaled digital photogrammetric maps was used. The study is performed in 100 km2 study area in Istanbul including various land classes such as open land, forest, built-up land, scrub and rough terrain obtained from Landsat data. The analyses were realized considering three vertical accuracy types as fundamental, supplemental, and consolidated, defined by national digital elevation program （NDEP） of USA. The results showed that, vertical accuracy of SRTM C-band DEM is better than optical models in all three accuracy types despite having the largest grid spacing. The result of SPOT-5 HRS DEM is very close by SRTM and superior in comparison with ASTER models.
