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LI Pingxiang YU Jie BIAN FulingLI Pingxiang professor State Key Laboratory of Information Engineering in Surveying Mapping Remote Sensing Wuhan University Luoyu Road Wuhan China. 《地球空间信息科学学报》2005,8(1):23-27
1 Extraction of the steep curve mapThe steep curve is defined as connection linefrom zero cross points which are produced fromthe convolution of Laplace ( LOG) filtration toDEM. Firstly, the elevation data from DEM areprocessed with LOG convolution and zero cross.The sampling formula is 2G(i,j) =12πσ6(r2 -2σ2)e-r2/2σ2 (1)where -M≤i≤M,-M≤j≤M,r2=i2+j2; M isthe filtration radius, nearly equaling to 5.1σ2; pre diction errorσis set to 4. Suppose that e[i,j] is asmall … 相似文献
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WU Jun CHEN DanqingWU Jun associate professor School of Geo-information Science Engineering Shandong University of Science Technology Qingdao China. 《地球空间信息科学学报》2005,(1)
IntroductionTexture extract from digital aerial image iswidely used for three dimensional city modelingto generate“photo realistic” views. Image de blurring is one of main problems in image pro cessing, and two classical methods, image en hancement and image restoration, are usually in volved. Both image restoration and image en hancement can upgrade the input blurred imageto some extent. Usually, the image restorationis specialized in deblurring image caused ma… 相似文献
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E. U. Onweremadu M.Sc. Ph.D. E. T. Eshett lecturer professor G. E. Osuji Head of department lecturer professor of soil conservation physics &environment 《International Journal of Environmental Science and Technology》2007,4(1):35-41
Studies on seasonal changes of heavy metal concentration in soils provide vital information for best management options at all times. The study investigated temporal variation in concentration of heavy metals in three towns having automobile service centres in Imo State. The study site is characterized by two major seasons in a year. Heavy metals were found in both arable and automobile soils, but more concentrations were recorded on the latter. Mean values of Cd, Cr, Ni, Hg and Pb were 6.2 mg/kg, 4.7 mg/kg 6.5 mg/kg, 0.02 mg/kg and 71.9 mg/kg respectively in the dry season while 2.9 mg/kg Cd, 2.2 mg/kg Cr, 1.9 mg/kg Ni, 0.01 mg/kg Hg and 51.9 mg/kg Pb were recorded during the rainy season of the experimental period. Higher values of heavy metal concentration were found in automobile soils as follows: 18.1 mg/kg Cd, 12.0mg/kgCr, 16.3 mg/kg Ni, 4.8 mg/kg Hg and312.8 mg/kg Pb in rainy season, and 15.1 mg/kg Cd, 8.1 mg/kg Cr, 11.9 mg/kg Ni 2.7 mg/kg Hg and 267.9 mg/kg Pb. However, Cd showed highest variability in arable soils during the dry season (CV=79%) while Hg varied widely in automobile soils in the rainy season (CV=54%). 相似文献
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WANG Guixian CHEN Zhicongand ZHANG Ren Associate professor Tsinghua University. Associate Professor Tsinghua University Professor Tsinghua University. 《国际泥沙研究》1991,(1)
The fluctuationg backwater region of a reservoir has a twofold property of a river as well as a reservoir and undergoes scouring and deposition alternately. Phys- ical model simulating the fluvial processes in a fluctuating backwater region has to ensure the similarities of both scouring and deposition. This causes some difficulties in model design and the selection of model sediment. This paper describes the model study of the fluctuating backwater region of the Gezhouba Project on the Yangtze River. Plastic particles with specific gravity of 1 .056 are used. The physical. model covers a reach of mountainous river 130 km in length. The experimental results show that the total amount of deposit, its distribution along the reach, the size distribution of the deposit, and lengths of the backwater region for various discharges all agree very well with the measured data in reservoir after 5 years of operation. This fact indicates that the model design, including the selection of model sediment, is quite acceptable. 相似文献
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Removal of lead from aqueous solution using low cost abundantly available adsorbents 总被引：4，自引：13，他引：4
N. T. Abdel-Ghani professor of analytical inorganic chemistry M. Hefny professor of physical chemistry G. A. F. El-Chaghaby research assistant 《International Journal of Environmental Science and Technology》2007,4(1):67-73
The removal of poisonous Pb (II) from wastewater by different low-cost abundant adsorbents was investigated. Rice husks, maize cobs and sawdust, were used at different adsorbent/metal ion ratios. The influence of pH, contact time, metal concentration, adsorbent concentration on the selectivity and sensitivity of the removal process was investigated. The adsorption efficiencies were found to be pH dependent, increasing by increasing the solution pH in the range from 2.5 to 6.5. The equilibrium time was attained after 120 min and the maximum removal percentage was achieved at an adsorbent loading weight of 1.5 gm. The equilibrium adsorption capacity of adsorbents used for lead were measured and extrapolated using linear Freundlich, Langmuir and Temkin isotherms and the experimental data were found to fit the Temkin isotherm model. 相似文献
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“Digital Region” in the Context of the “Grid Computing” 总被引：1，自引：0，他引：1
Introduction“Grid”computinghasemergedasanimportantnewfiled ,distinguishedfromconventionaldis tributedcomputingbyitsfocusonlarge scalere sourcesharing ,innovativeapplications,andinsomecases ,high performanceorientation .Theconceptofthe“SIG”(spatialinformation grid)whichisbasedonthegridcomputingandisthein frastructureandusefultooltoconstructthe“digitalregion”.Theregionalsustainabledevelopmentevaluationsystemisthefoundationoftheregionalsustainabledevelopment,whichistoocomplextoestablishane… 相似文献
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M. R. Samarghandi M.R. M.Sc. Ph.D. J. Nouri Associate professor A. R. Mesdaghinia Professor Chairman A. H. Mahvi Associate professor S. Nasseri Professor F. Vaezi Associate professor 《International Journal of Environmental Science and Technology》2007,4(1):19-25
A variety of processes can be used in treatment of industrial wastewaters. The relatively newest of which is photo catalysis with titanium dioxide which may also be used plus hydrogen peroxide to improve the treatment rate. In this study, photo catalysis/ hydrogen peroxide processes had been employed for the removal of phenol, lead and cadmium by three different pHs of 3.5, 7 and 11. The treatment tests were also accomplished without UV irradiation. In both experiments, the variables were pH and concentrations of reagent chemicals, but the detention time was kept constant (180 min). Results indicated that the optimum efficiencies of phenol and Cd removal were 76 % and 97.7 % at pH=11, respectively, and for lead, it was 98.8% in all pHs. In other words, no pH dependency was regarded for lead treatment. These results were all obtained by simultaneous use of UV irradiation with 3 mL/L H2O2 and 0.8 g/L TiO2. Finally, the best pH for treatment, when all the three contaminants are presented is considered to be at 11. These results should be regarded by all industrial treatment plants which have experienced the problem of these three special contaminants in their effluents. 相似文献
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Coastline change detection using remote sensing 总被引：3，自引：3，他引：3
A. A. Alesheikh Assistant professor A. Ghorbanali N. Nouri 《International Journal of Environmental Science and Technology》2007,4(1):61-66
Coast is a unique environment in which atmosphere, hydrosphere and lithosphere contact each other. Coastline is one of the most important linear features on the earth’s surface, which display a dynamic nature. Coastal zone, and its environmental management requires the information about coastlines and their changes. This paper examines the current methods of coastline change detection using satellite images. Based on the advantages and drawbacks of the methods, a new procedure has been developed. The proposed procedure is based on a combination of histogram thresholding and band ratio techniques. The study area of the project is Urmia Lake; the 20th. largest, and the second hyper saline lake in the world. In order to assess the accuracy of the results, they have been compared with ground truth observations. The accuracy of the extracted coastline has been estimated as 1.3 pixels (pixel size=30 m). Based on this investigation, the area of the lake has been decreased approximately 1040 square kilometers from August 1998 to August 2001. This result has been verified through TOPEX/Posidon satellite information that indicates a height variation of three meters. 相似文献
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