最新刊期
卷 ， 期 5 ， 2003
- 摘要：Responding to the urgent needs for preventing and curing SARS diseases, the researchers take the advantages of developed-independently GIS platform, SuperMAP software series, and the spatial assistant decision-making models to develop the National SARS Disease Controlling and Pre-warning Information System （NSIS）. There are five sub-modules in NSIS, which integrates the technologies of spatial location, management and analysis of spatial information and communications and facilitates the real-time collection, management, analyzation, and dissemination of SARS diseases information together with the monitoring, prevention and curing of SARS diseases.关键词：SARS;controlling and pre-warning;Information system;SuperMAP
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发布时间：2021-06-10 - 摘要：This paper introduces and sets up some kinds of nonlinear growth models, the SI（Susceptible and infective） model and piecewise SI model, for forecasting clinical diagnose cumulative SARS（Severe acute respiratory syndrome） cases is Beijing. The 95% confidence interval of the time change point on piecewise SI model is made well which includes April 21, 22 and 23. It means some control policies in Beijing at the end of this April 24 played an important role for anti-spreading of SARS, after change of increase rate for SARS cases is quite significant.关键词：Severe Acute Respiratory Syndrome（SARS）;susceptible and infective model;piecewise susceptible and infective model;change point
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发布时间：2021-06-10 - 摘要：In this paper, Geostationary Meteorological Satellite （GMS） infrared blackbody temperature （Tbb） data from June to August 1998 are used to automatically track the activity of Mesoscale Convective Systems （MCS） over the Tibetan Plateau. Consequently, the features of MCS, such as area, intensity, life cycle, activity region and shape, are obtained. High Resolution Limited Area Analysis and Forecasting System （HLAFS） values provided by China National Satellite Meteorological Center are used to study the relationships between the MCS movement routes and their environmental physical field values, based on the distribution and movement routes of MCS over the Tibetan Plateau. Favorable environmental physical field charts of influencing MCS movement ouf of the Tibetan Plateau in different UTC are developed using spatial data mining techniques at levels of 400hPa and 500 hPa, respectively.
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发布时间：2021-06-10 - 摘要：Remote sensing image classification is one of the basic components in remote sensing image processing, which is the key stage in remote sensing applications. There are two ways to get a higher precision: one is to make full use of spectral information, and another is to add other new information The later is called multi-information processing. Spatial information is one of the most important information in these kinds of multi-information. Since lack of information is always the key problem in remote sensing image processing, we propose a spatial information based method to cope with this problem. What we used is not the spatial data but the spatial characteristics. The main advantage of our method is that it can work without any other data sources. We take advantage of spatial autocorrelation law, which is the first law of geography. The law is widely used in geo-analyses. It denotes that the closer in spatial, the similar the objects or phenomenon is. Two spatial bands are constructed based on spatial autocorrelation law and a spatial classification result is produced. These two additional bands containing spatial location information are used in classification. One real class may be divided into many classes that are not similar in space. But every class has similar spectral and spatial characteristics. Based on the classification results, further processing should be done. First, we replace every pixel value of every spectral band with the average spectral value of its class. Then a traditional classification method, such as ISODATA method, can be used. With these steps, we get the last classification results. The MAS and ASTER images are used to prove our method. The classification results show that some miss classified ground covers in the general spectrum based classification method are thrown off by our method. In other words, our method is resistant to the problem of having apparent same spectrum but different ground cover. Another distinct advantage of our method is about the removal of salt and pepper noise from images. It may be also helpful in other research area, such as landscape research. Our method also proves the importance of spatial information in remote sensing image classification. It gives an easy way to add spatial constraint to classification process. The new classification method reveals its simpleness and practicality.关键词：remote sensing image;classification;spatial information
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发布时间：2021-06-10 - 摘要：We present a modeling approach to assess the robustness of remotely derived spectrometric equations predictive of rice leaf chlorophyll concentration to the view direction. Our methodology uses two radiative transfer models that operate at leaf（PROSPECT）and canopy（FCR）levels. It includes three stages:（1）Simulation canopy bi-directional reflectance on varies leaf chlorophyll concentration, varies leaf area index（LAI）and varies understory;（2）establishment of predictive relationships of chlorophyll concentration with stepwise regression;（3）assessment of the robustness of these relationships. First, we simulate rice leaf spectrum by PROSPECT model. The parameters used in the model are: protein concentration（0.0008g/cm2）, cellulose concentration（0.0049g/cm2）, water equivalent thick（0.02cm）and leaf structure parameter（1.7）, while chlorophyll concentration varises from 20μg/cm2 to 40μg/cm2, the change step is 0.1μg/cm2; simulate rice canopy bi-directional reflectance by FCR model. The parameters used in the model are: leaf relative linear size（0.40）, model inclination（81）, model eccentricity（0.9985）, sun zenith angle（32°）, sun azimuth angle（0°）, and sun direct radiation/total radiation（80%）, the changed parameters are LAI, view direction and understory spectrum character. LAI varies from 1 to 7. The change step is 1. There are four view directions: nadir view direction（both view zenith angle and azimuth angle equal to 0°）, hot spot view direction（view zenith angle equals to 32°, azimuth angle equals to 0°）, oblique view direction（view zenith angle equals to 32°, azimuth angle equals to 90°）and specular view direction（view zenith angle equals to 32° azimuth angle equals to 180°）. The reflectance of three types of understory are measured in 1999. Second, the established multiple linear regression model by stepwise regression analysis uses simulation values（LAI are 1,3,5 and 7, chlorophyll concentration varies from 20μg/cm2 to 40μg/cm2, three types of understory）on different directions to predict chlorophyll concentrations. The considered factors are canopy reflectance R λ, derived ln（1/R λ）and R′ λ. The regression equations are established by SPSS software. The selected wavelengths are upon F probability and root mean square error（RMSE）. Only when rejection probability is less than 0.05, the wavelength can be selected. To make the equation simple, we just chose three wavelengths which partial correlation index is the biggest for each regression equation. Then, the robustness is valued by compound coefficient of correlation（r2）and RMSE. For the equations establishment by the three factors（R λ, ln（1/R λ）, and R′ λ）, r2 on nadir view direction are 0.905, 0.916 and 0.883, on hot spot view direction are 0.774, 0.962 and 0.747, on oblique view direction are 0.563, 0.941 and 0.572, on specular view direction are 0.881, 0.937 and 0.883, RMSE on nadir direction are 1.97, 1.68 and 1.99, on hot spot view direction are 2.75, 1.13 and 2.92, on oblique view direction are 3.83, 1.41 and 3.80, on specular view direction are 2.00, 1.45 and 1.98. Those stress that the robustness are strongest on ln（1/R λ）and nadir direction. The equations on nadir direction are: chl=19.882+5747.957R 410-3770.780R 415-414.002R 705（1） chl=74.631-224.236ln（1/R 410）+190.960ln（1/R 415）+39.24ln（1/R 715）（2） chl=59.526-149370.7R′ 420+131394.74R′ 555+28899.908R′ 585（3） in the equations, chl indices chlorophyll concentration. We predict chlorophyll concentrations by nadir direction equations use simulated reflectance on other directions and see bigger RMSE occurred（for example, the biggest RSME is 26.74 on specular view direction）. It stresses that the equations built on nadir view direction are unsuitable for other directions’ prediction. When we predict chlorophyll concentrations by nadir direction equations use simulated reflectance on nadir direction（LAI equal to 2, 4 and 6, chlorophyll concentration varies from 20μg/cm2 to 40μg/cm2, three types of understory）, we find that the predictive accuracy is关键词：linear regression;chlorophyll concentration;robustness analysis
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发布时间：2021-06-10 - 摘要：Aerosol optical depth, one of the important parameters to describe the property of aerosol, is widely used in the region of Radiative Transfer and Atmospheric Correction; but at the same time, Meteorological Range but not Aerosol Optical Depth is used as an input parameter for the famous Radiative Transfer program: MODTRAN. It is reasonable to get the relative between Aerosol Optical Depth and Meteorological Range for the convenient using of all kinds of aerosol data. Though there are many expressions to describe the relative between them, the analysis in this paper shows that their relative change with the season change of aerosol profiles. An empirical expression was given here based on the simulation using MODTRAN4, and the coefficient of formula is different with the seasonal change of aerosol profiles. If this difference is ignored, the error of aerosol optical depth error may reach the level of 0.029 when the same meteorological range is transformed.
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发布时间：2021-06-10 - 摘要：In this paper, we propose a new denoising method, which distinguishes the coefficients’ extremums belonging either or to image to noise by the tracking matrixes of the extremums in wavelet domain. The coefficients’ extremums that belong to image have transmission property from coarse to fine scale, but the coefficients’ extremums that belong to noise do not have. We evaluate the tracking marixes of the extremums different number base on the transmission property of each extremums from coarse to fine scale. The tracking matrixes of the extremums express the different transmission property. By the tracking matrixes of the extremums, we differentiate the wavelet coefficients’ extremums and then remove the coefficients’ extremums belonging to noise. Experimental results show that the denoising proposed in this paper is effective both in reserving the edge and in removing noise.关键词：wavelet transformation;Extremum;Lipschitz exponent;Singular points
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发布时间：2021-06-10 - 摘要：Frame Synchronizer is one of the key devices in satellite ground receiving stations. Based on the rapid progress of the FPGA technology, a high-speed remote-sensing multi-satellites universal frame synchronizer is developed. The analysis of key technology and system performance is described. The Universal Frame Synchronizer features high density, small size and high noise-tolerant capability. Such a single standalone frame synchronizer can be used for most national and international remote-sensing satellites.关键词：Ground Receiving Station;Frame Synchronizer;FPGA
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发布时间：2021-06-10 - 摘要：Speckle noise is a common phenomenon in SAR images. The reduction of Speckle is necessary for any further processing of SAR image such as segmentation, classification and other procedures for information extraction. ln this paper, after a brief review of conventional filters for SAR speckle reduction, a wavelet-based soft-thresholding filter for SAR speckle reduction is presented. To evaluate the performance of this filter, the adaptive local statistics filters, which include Lee, Frost, Enhanced Lee, Enhanced Frost, Kuan, and the Gamma-Map filter, are applied to the speckle reduction for the same type SAR image. The performances are compared in several aspects including Radiometric preservation, feature preservation, speckle reduction in the extended uniform regions and the absence of artifacts. The results show that the wavelet-based speckle reduction filter performs better in every aspect in evaluation than the conventional filters do.关键词：speckle;Wavelet analysis;soft thresholding filter;adaptive local statistics filter;performance evaluation
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发布时间：2021-06-10 - 摘要：Every pixel in the super space is required by K-means algorithm to calculate Euclidean distance for clustering.When there are many class centers,this is a rather time consuming work.In this paper,an improved K-means clustering algorithm is presented to save initial clustering time by making initial division based on previous clustering results,to remain the stable relationship between classes,and to accelerate clustering process with more and more classes becoming stable by judging the centers nearest to the pixel.A new clustering lossless compression algorithm designed here can determine the best class number and the highest compression ratio by fully utilizing previous clustering results and converging quickly eliminating the inter-spectral redundancy and intra-intra-spectral redundancy through enhancing the intra-class pixel redundancy.The convergence of this algorithm and existence of the best parameters are also inferred by making a deep analysis of the probability distribution model of the residue data.Furthermore,the comparison with DPCM lossless compression algorithm in the entropy value of the probability distribution model and the experimental results show that this clustering algorithm is better than non-clustering compression algorithm.Several times clustering approach can forecast the best class number with the least entropy lossless compression.关键词：Hyperspectral images;Lossless compression;Entropy;K-means clustering
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发布时间：2021-06-10 - 摘要：Remote Sensing image fusion is an effective way to use the large volume of data from multi-source images.This paper introduces a new method of remote sensing image fusion based on support vector machine （SVM）, using high spatial resolution data SPIN-2 and multi-spectral remote sensing data SPOT-4.First the new method is established by building a model of remote sensing image fusion based on SVM.Then using SPIN-2 data and SPOT-4 data, to test image classification fusion.Finally, an evaluation of the fusion result is made in two ways: （1）From subjectivity assessment, the spatial resolution of the fused image is improved compared to the SPOT-4, and it is clearly that the texture of the fused image is distinctive; （2）From quantitative analysis, the effect of classification fusion is better.As a whole, the result shows that the accuracy of image fusion based on SVM is high and the SVM algorithm can be recommended for application in remote sensing image fusion processes.关键词：image fusion;SVM;multi-spectral image;panchromatic image
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发布时间：2021-06-10 - 摘要：The main role of map is confined to representation of various kinds of decision schemata and appraisal results. But it almost does no good to the understanding and definition of problems. The concept map is a new method that can support the knowledge derivation and knowledge sharing. Through the concept map method the new knowledge can be effectively obtained. The experiential knowledge of different user and expert can be organized through the concept entity and concept relation and represented visually as map, thus support the geo-model construction. The Geo-model construction process based on concept map has 5 steps: Geo-model description, Geo-model definition, model construction, transformation from Geo-model to computational model, and CASE generation. Then we discuss in detail the characteristic of the model supporting system and the visual model construction environment. Finally the background data, such as the water engineering distribution and spatial data, of the Yongdinghe Watershed is used to support the construction of Concept Map model of the Xiaoqinghe floodplain, on which the flood simulation model of the Yongdinghe River and the Xiaoqinghe floodplain is constructed. The flood simulation result is overlaid with social and economic data to evaluate the flood disaster loss and the results is satisfactory and encouraging.关键词：concept map;Geo-model construction;computational model;Xiaoqinghe Floodplain;flood simulation model
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发布时间：2021-06-10 - 摘要：Land surface temperature derived from brightness temperature dataset and NDVI dataset were used to construct the NDVI/T s space, from which a dryness index-temperature/vegetation dryness index （TVDI） was suggested. The dryness index that combines the land surface temperature with vegetation spectral index is computationally straightforward because it is based on the information derived from satellite data only. Using the TVDI, the surface moisture status in China in March and May in 2000 was studied. The results showed that the severe drought was mainly distributed in North-western China and part of North China and South China; the severe drought area enlarged from about 67×104km2 in March to 126×104km2 in May. TVDI spatial pattern was compared with the measured topsoil moisture from the observatories around China with the linear regression method. A negative linear correlation between TVDI and the measured soil moisture was found, thus TVDI ’s validity in evaluating drought was verified. Afterward, the sensitivity of TVDI to NDVI and T s was evaluated. The results show that the TVDI are more sensitive to the land surface temperature than to NDVI and land surface temperature have more drought information than NDVI which lead to the conclusion that dryness indexes based on land surface temperature are more reasonable than the ones based on NDVI.
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发布时间：2021-06-10 - 摘要：Human interventions in natural systems have resulted in large change in vegetation composition and distribution pattern. The Land Use Change and Climate Change （LUCC） study under the International Geosphere Biosphere Program（IGBP） is a major initiative in this regard. Grassland change plays an important role in global change. This paper dynamically monitors status of grassland change in China from 1980s to 2000 based on RS & GIS. The data are extracted from LANDSAT TM image. From these data, the type of land use is decided on basis of the interactive MGE environment. To diminish the geometric error of the image, we adopt the processing method of Least-Square. As for pixel sampling method, we adopt the method of Nearest Neighbour Interpolation or Bilinear Interpolation. After the image processing, the maximum geometric errors are 2-3 pixels. The task of image classification is mainly taken by experts with the help of relief map, navigation photo etc, thus landuse coverage could be acquired. In the study, following conclusions can be drawn:（1）There is obviously zone difference of grassland dynamic change in China. From grassland being changed to farmland, mainly occurs in Heilongjiang province, Jilin province, Liaoning province and east Inner Mongolia. From the grassland being turned to urban, affects the relationship with regional population, economic development. From the grassland being changed to forest, mainly concentrates in southeast littoral; Grassland degradation is mainly distributed in Inner Mongolia, Xinjiang, and Qinghai. Grassland change bears on natural condition, but human activities have heavily impact on it. Grassland degradation has adverse impact on environment, especially north China and it will restrict regional economic development.（2）As for the grassland’s change, there are many phenomena of farmlands occupy grasslands. The farmlands occupation of grasslands plays a leading role in the change. The occupation by farmlands is more serious in arid and semi-arid regions. The grassland’s occupation by farmland at different levels for all coverage levels of grassland is mainly located in the non-monsoon zones.（3）The main reason of the grassland area decrease and coverage level reduction is that the resources’ functions are continually greatly wrested under the push of human demand for economy and the dictate of benefit. This is also the contradiction between the development and ecologic administration which are faced by the west regions of our country.
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发布时间：2021-06-10
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