最新刊期
卷 ， 期 4 ， 2003
- 摘要：This paper summarizes the activities of "Severe Acute Respiratory Syndrome（SARS）spread Trend"project conducted by experts on WebGIS,virtual geographic simulation and applied statistics. The project focuses on analysis and prediction of middle-long term spread trend of SARS with national and metropolitan scopes by developing "2-scale temporal-spatial model"and "SARS Web-GIS".关键词：Geographic space information;SARS epidemic situation;Temporal-spatial distribution;2-scale temporal-spatial model
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发布时间：2021-06-10 - 摘要：This paper introduces some kinds of nonlinear growth curve for forecasting cumulative SARS patients, it is shown that the Richards curve is reasonable and flexible in this SARS forecasting. The nonlinear growth curve regression model is established for forecasting cumulative SARS patients.Specifically,the SARS situation forecasting in Beijing is made well which includes forecasting based on comsecutive and piecewise time fitting. It means some control policies in Beijing at the end of this April play important role for anti-spread of SARS,and also provides a good basis for future works.关键词：SARS;growth curve;nonlinear regression model;Richards growth curve;piecewise time fitting
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发布时间：2021-06-10 - 摘要：In the beginning of this year,SARS（Severe Acute Respiratory Syndrome）broke out and spread in mainland of China,Hong Kong,Taiwan and other countries,regions successively. The world,especially China,pays high attentions on this public hygiene safety affair and takes various measures to prevent and control the further spreading of SARS.This work began in early April in this background.At this time,the SARS began to spread to Beijing and northern regions of China, but the situation in southern regions,such as Guangdong and Hong Kong is relative stable. The data about SARS spreading,special cases and sources in these regions are available.Through these information,we found the spreading characteristic of SARS has a distinct one besides other common ones,namely,jumped sperad between two points in long distance.This characteristic can not be singly described by the diffusion models for point sources. Pointed to this, a "fly dots"spreading model along transportation is put forward in this paper,which takes the vehicle as a scale and sets up SARS spreading model in the relative sealed vehicle. Based on this model,in a scale of the transportation, the spatial spreading of SARS due to flow of passengers is modeled. We simulatde the danger probability of SARS sperading, three cases reported in internet,and the affect of Beijing SARS epidemic situation to in Hebei province due to flow of passengers.The results show that this model meets the spacial spreading characteristic of SARS. Not only the vent,and disinfect and others measures affect SARS spreading in vehicle,but time is also an important factor to be considered. The SARS spread along transportation is affected by these regions’ population distribution,the SARS epidemic situation in the beginner affect the situation in the regions of the stops in a great degree. The results simulated by the models can be used to support the decision-making关键词：SARS;transportation;"fiy dots";spreading model
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发布时间：2021-06-10 - 摘要：This paper presents one solution to WebGIS-based SARS information system of high-visits and points out that "thin-server" mode is one best solution to WebGIS application of high-visits. The system architecture and main application interfaces are given in detail.关键词：SARS;High-Visits;Thin-Server
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发布时间：2021-06-10 - 摘要：A Severe Acute Respiratory Syndrome （SARS） spread model based on System Dynamics （SD）approach is implemented to do the quantitative analysis of the critical importance of control policies such as early report, early quarantine, and early hospitalization to control further SARS epidemic spread. Using this model, a case study on Beijing SARS epidemic situation is conducted. The simulation results show that the onset-to -hospitalization interval and effective quarantine are two key factors in SARS transmission. Furthermore, the shortening of onset-to-hospitalization interval should be given the highest priority. In addition, a period based simulation is carried out to analyze SARS spread and control effectiveness in Beijing. The simulation outcome demonstrates that various control measures after April 20,2003 in Beijing and the public holidays starting from May lst to May 5th have a significant impact on containing the epidemic situation. The most dangerous days, around April 27, when the number of uncontrolled SARS patients in the society reached at its peak, can also be calculated. The SARS infectiousness number newly reported in Beijing has been at a low level since May 20. But simulation experiments describe that it may fluctuate with import of SARS infectiousness from outside Beijing, weakening of quarantine, more social activities, and so on.关键词：SARS;system dynamics models;simulation;control measures
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发布时间：2021-06-10 - 摘要：Based on activities of SARS control in China and theory of human-earth systems science, a logic model of transmission channels of pathogenic factors in the processes of interaction between human and earth, and a logic model of interaction between human and earth for SARS control are sequentially presented. According to the latter, the spatial transmission patterns of SARS in China are separated into 5 modes: 1) pathogen transferring mode from wild animals to human beings;2) contact infectious mode in family and community;3) infectious mode in hospitals and clinics;4) random diffusion mode in urban area, and 5) jumping transmission mode among cities, regions and countries. The last one among them is a very complicated and difficult one to be controlled. Therefore, the mode is the most important target and task to be controlled in SARS outbreak. Correspondingly, a recommendation on the response mechanism of public health emergencies in China and the conceptual structure of surveillance and control information system with the mechanism are presented in order to control the effects caused by the mode mainly and efficiently.关键词：SARS;infectious diseases;epidemiology;human-earth system;transmission patterns;logic model;surveillance and control information system;emergency control mechanism;digital ID card
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发布时间：2021-06-10 - 摘要：This paper introduces the study for population migration in mainland China and its applications to SARS control. This paper analyzes following issues by using Geographic Information System, （1）the characteristics of immigratory population and migratory population in cities,（2）inflow spatial features for migrant workers in Beijing and Guangdong respectively, （3）situation prediction for migrant workers reflunce to Beijing, and （4）spatiallg distributing features for SARS along traffic lines. According to above studies, some elementary information can be given for SARS control decision-making. （1）The cities, where immigratory population are more than or less than migratory population and the situation along the traffic line can be pointed out here, and how to take measures to cut off the disease of spreading in these cities is obvious;（2）The study on migrant workers can provide some advise to the rural SARS control measures, such as quarantine measures;（3）According to phenological statistic and some raw data for migrant workers, some predictions for the rush hour of migrant workers, who inflow Beijing again refluence can be given roughly.关键词：population migration;spatial characteristics;migrant worker;refluence;SARS control;Macro-decision-making
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发布时间：2021-06-10 - 摘要：The field spectra reflectance data selected at key growth stages of winter wheat were analyzed. It indicated that the wavelength bands related to leaf nitrogen content selected by regression equation located at 820-1100nm and 1150-1300nm. The proper spectrum reflectance form should be established for donating the spectrum reflectance and leaf nitrogen content at different growth stages. The proper forms were as following: the regression equation of derivative form at reviving stage, and the reciprocal form at booting stage and the basic form at ripening stage. The results showed that there were robust correlations between leaf nitrogen content and other leaf biochemical constituents, dried biomass indicators and grain quality indicators. The regression equations between leaf nitrogen content and other leaf biochemical constituents, dried biomass indicators and grain quality indicators were established. The predictions of soluble sugar content, leaf water content, stem water content, leaf starch content, leaf dried weight, plant dried weight, and LAI etc. by leaf nitrogen content were feasible. It has very significant level among grain protein, dry gluten content and leaf nitrogen content at anthesis stage, and no significant correlation of leaf nitrogen content and other grain quality indicators. So it is feasible for forecasting the grain protein and dry gluten content by leaf nitrogen content data acquired by remote sensing.关键词：hyperspectral data;leaf nitrogen content;biochemical component;grain quality
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发布时间：2021-06-10 - 摘要：SAR is an all-weather remote sensing technique which achieves high resolution and large swath widths. It is rapidly becoming a key technology in remote-sensing applications. SAR uses a short chirped pulse and matched-filter processing to obtain fine range resolution. Fine azimuth resolution which is range-independent is obtained by using the platform motion and coherent processing of Doppler-shifted radar pulses to synthesize a large antenna. Due to environmental disturbance and limitation of the SAR facility and handling techniques, errors, including random errors, system errors or both, would occur in each system node or subprocess of the overall SAR imaging process. These errors may greatly affect the quality of SAR images and lead to the uncertainty in their eventual application. For example, phase error may severely blur and deform SAR images. Image defocusing, radiometric distortion, and increased sidelobe levels hamper target detection and recognition. Geometric distortion prevents direct pixel-to-pixel comparison of SAR images or the matching of SAR with other forms of imagery It is crucial to understand the nature of error and the way they affect the quality of final images through error propagation and synthesis. Generally speaking, the sources of uncertainty in SAR system include the instability of SAR sensor, navigating system, platform motion and its motion compensation, SAR digital imaging process, image process and etc. These error sources could cause phase error, positional error and gray level error which are embedded in the final corrupted image. Currently, processing of gray level error includes radiometric calibration, speckle noise reduction and radiometric enhancement,positional error, handled by geometric coarse correction and geometric fine correction. Presently, the solution of phase error and positional error falls mainly in motion compensation,it is related with the Inertial Navigation System, SAR data driven process, and the combination. The relationships among on phase error, gray level error, and possibly positional error and their synthesis, though important, have not been investigated. Furthermore, the way these errors propagate in terms of mechanism from error sources through the SAR imaging process has seldom been made. A thorough examination of these aspects will prove to be crucial in uncertainty management and quality improvement of SAR images . The purpose of the present study is to make an initial attempt to probe into various sources causing phase error, positional error and gray level error, and to establish a relationship among these errors. We also investigate the mechanism-based propagation of errors along the SAR imaging process, their final synthesis and impact on the quality of SAR images.
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发布时间：2021-06-10 - 摘要：Terrain landform features play major roles in such fields as geomorphology type recognition, relief map generalization, DEM construction and hydrology analysis. This paper presents an automatic method to extract terrain landform features and organize drainage system into tree structure based on bend assessment using Delaunay triangulation model. Compared with traditional DEM or TIN based methods, this pure vector approach obtains not only the topological structure of drainage system in planar graph, but also the valley distribution polygon range. Depending on geometrical computation and judgment of vector line, polygon, the structured properties in drainage representation is enhanced, avoiding the case of noise disturbance in DEM based method. The core algorithm makes use of the ability of Delaunay triangulation in detecting hierarchical structure of each contour line. Three kinds of tree structure organization are discussed: the hierarchical binary tree representing bend inclusion relationship contained in single contour line, the plane structure tree representing valley topological relationship, the semantic hierarchical tree representing valley join level from the point of view of hydrology. This paper gives systemically experiment and detailed comparative analysis.关键词：Delaunay triangulation;landform features;drainage system;spatial analysis;map generalization
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发布时间：2021-06-10 - 摘要：The zero-crossings and the maximum of the wavelet transform are very effective for locating the edges of the image function. In this paper, we investigate the properties of the zero crossing and the maximum related the wavelet transform which are derived from the first derivative or the second derivative of the smooth function respectively. Multiscale wavelet transform provides a pyramid hierarchic descriptive method of image features. Its main advantages are that both the algorithms involved do not create false generic features and the difference of edges derived from two near scale wavelet transforms is not larger than one pixel. Mallat discrete dyadic wavelet transform has the advantages. In multiscale wavelet transform, if a scale is bigger, the edge contour of image will be derived and the detail information be blurred or lost. If the scale is smaller, the details in image can be detected, in the same time, finer noise in image will be also kept. The object scale changes in remote sensing image occur over a wide range and vary unpredictably over the image. It is difficult to select an adaptive scale before or in the wavelet transform. Inspired by the scale-space theorem and wide and unpredictable scale changes in remote sensing image as mentioned above, and based on zero crossings of 2D multiscale wavelet transform, the arithmetic of focusing edge in dyadic wavelet transform is introduced as follows. 1) The image function f（x,y）is transformed by 2D Gaussian symmetric wavelet at dyadic scales, and subsets {W 2jf（x,y）,0≤j≤n} related the transform are stored. The edge features in subimage W 2nf（x,y）（at scale j=n） are detected by zero-crossings of Gaussian symmetric wavelet transform and the map related to the edge features is derived and stored. 2) A special region around the edge related to W 2jf（x,y）（j≤n） is selected as a searching area. The edge features in subimage W 2 j-1f（x,y） are detected by zero-crossings of the same transform around searching area and a new edge map is derived. The former edge map is updated by the new edge map. 3) j=j-1,if j=0 stop ,else go to step 2. Experiments show that the arithmetic is effective to solve the problem, in which the object scale in image function is uncertain. The method is not only to eliminate fine scale noise and locate edge accurately,but also to extract edge contour correctly at larger scale.关键词：2D wavelet transform;edge operator;multiscale focusing edge
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发布时间：2021-06-10 - 摘要：An anomaly detection approach based on feature fusion is presented in this paper.All the detection algorithms,aside from anomaly detection,require training pixels of the desired class.Anomaly detection is the detection of scene elements that appear unlikely with respect to a probabilistic feature of the scene.The method needs on prior information,but the result has much false alarm.In this paper,we use low probability detection to fuse the data in feature level;then segment the image and detect anomaly elements.The result eliminates much false alarm and improves the detectability.We apply the method to the data produced by OMIS system and achieve satisfying results.关键词：hyperspectral image;anomaly detection;low probability detection;OMIS system
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发布时间：2021-06-10 - 摘要：Extracting residential information by remote sensing technology is significant for the loss estimation of natural disaster and the study of urban extension and environmental change.In this paper,taking Jiangning county of Nanjing as a case study area,the extraction of re sidential information from SPOT images is discussed.Firstly, the characteristics of residential areas in this area on this image are studied,secondly,spectral characteristics of residential areas and other land-use types on SPOT-4（XI） image are analyzed to find the possibility of extracting residential areas from the background according to spectral characteristics.Thirdly,a simple model of decision tree is proposed on the basis of spectral magnitude relations and some proper thresholds of residents and other land-use types.But some roads still cannot be separated from residential areas because their spectral characteristics are similar.Therefore,their shape characteristics are analyzed.The result is generalized and converted to vector coverage.Then the shape indexes of every spots are calculated and categorized choosing a threshold to remove the roads.Finally,the vector coverage of residential areas is overlaid on the original image to check the effectness of this model,and an accuracy assessment is given to the result by random samples.The results suggest that this model is simple and effective,especially for the residential areas over 10000 m2,and the analyzedfor is much higher than the supervised classification’s,however,some pixels near the water-bodies and the roads are judged by mistakes.This problem can be solved by the rule judgment based on the knowledge of spatial relations.Therefore,the cities,towns and villages in the south of Yangze River where there are various types of land cover can be extracted from the images by this model,and the model is not limited by the time,only the thresholds will be changed.关键词：SPOT images;residential information;automatic extraction;decision tree algorithm
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发布时间：2021-06-10 - 摘要：This study has confirmed and reclassified the ENSO events, which are considered as the strong signal of interannual climate variation, during 1982 to 1993. Based on the AVHRR NDVI database, which are offered by USGS EROS data center and have 8km spatial resolutions and 10 days temporal resolutions, calculated annual averaged NDVI images of 5-9 months during 1982 to 1993 using GIS technology. With the averaged NDVI images, the spatial distribution of east Asian land cover in ENSO years using Data Profile Analysis method. At the same time, applied Primary Component Analysis method made calculations on same time series NDVI images ,and identified the spatial distribution of land cover reflected by the 7th component of PCA analysis is the same as the results of Data Profile Analysis. Furthermore, the relationship of the eigenvector of the component 7 and Southern Oscillation index（SOI）, which represents the characteristic of ENSO changes, during 1982 to 1993, and the characteristic of spatial distribution of east Asian land cover’s interannual changes which are being driven by changes of ENSO events was summarized.关键词：East Asian land cover;ENSO events;data profile analysis;primary component analysis;response characteristic
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发布时间：2021-06-10 - 摘要：Using ground based remote sensing, multiple angle observational experiment for the scattering of synthetic aerosol of the main types of air pollution in Beijing was carried out. The scattering characteristics of synthetic aerosol in different air pollution types, and under different observational angle, are compared and analyzed, and then draw to the conclusions that:（1） the composition of synthetic aerosol can be reflected by its scattering coefficient curve. To the pollution type whose synthetic aerosol is mainly composed of coal smoke and soluble particles, the curvature of scattering coefficient curve changing with wavelength are obviously larger than that of the pollution type whose synthetic is mainly composed of sand and dust. The amount of synthetic aerosol is reflected by the value of scattering coefficient. （2） Synthetic aerosol on slightly polluted urban area are mainly composed of coal smoke and soluble particles, and in the composition of the synthetic aerosol on the area near large plants or on traffic line, both of coal smoke and dust are very high. （3）When zenith angles of sunlit and observation are larger than 40°, the change of observation angle only have slight influence to the result of observation. The change of zenith angle on the direction perpendicular to solar principle plane has far smaller influence on the result of scattering coefficient observation. Base on the result of experiment, the numeric model for simulating synthetic aerosol scattering is built, laying a base for the space-bone remote sensing of synthetic aerosol.关键词：air pollution;synthetic aerosol;scattering coefficient;remote sensing
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发布时间：2021-06-10 - 摘要：The Guanting Reservoir will be the second water resources of Beijing for drinking, but the alluvial problem has been puzzling for decades. The paper studied the shoreline dynamic evolution of the Guanting Reservoir from 1988 to 2001 using change detection technique, with multitemporal Landsat TM data（1988, 1994, 2001）. After geocorrecting and radiometric normalization, principal component analysis and global change detection method was used. Several problems, such as reservoir silting, shoreline types etc.,have been discussed. The remotely sensed temporal and spatial analytic method to shoreline slope and shoreline stability discriminant have been presented, according to the relationship of proportion between the width of change detections and difference of water level on shoreline. With this method, shorelines were chassified to 3 types, alluvial, erosive, as well as balance shoreline. The affects of the above-mentioned factors to the water resources in the Reservoir have been analyzed. The shoreline stability discriminant will be applicable potentially on the low-lying beach areas of ocean and lake, andgle between 0 001-0 1°关键词：remote sensing;change detection;shoreline;Guanting Reservoir
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发布时间：2021-06-10 - 摘要：The precipitation radar （PR）, the first space-borne rain radar, carried by Tropical Rainfall Measuring Mission （TRMM）satellite, has provided a new sounding method for atmospheric research and has played an important role in understanding the circulation of global energy and water for five years. In this paper, the data of Fuyang ground-based radar and PR data, both obtained from Huihe River Basin Experiment （HUBEX）in 1998 and 1999, have been compared in three aspects, 1) Distribution of echo intensity, 2) Averaged reflectivity profiles, 3) Sensitivity Analyses indicate that Fuyang radar is better than PR in sensitivity and horizontal resolution, but the observing error still exists in data because of attenuation-influence and beam-width influence. The farther the observed region is away from Fuyang radar station, the more difference between the observed value and true value is. The wavelength of PR is shorter than the Fuyang’s therefore the PR is more sensitive to the attenuation in strong echo. Especially when the strong attenuation is encountered, the corrected echo value of PR is still smaller than the true value. The way of PR detecting precipitation clouds, from space to surface, is thoroughly different from Fuyang ground-based radar’s. The PR data can easily avoid the attenuation-influence in horizontal direction. The vertical resolution of PR data is much better than the Fuyang’s and the PR data is symmetrically distributed in spatial domain which is dislike Fuyang radar data, so a new effective method for correcting echo value of Fuyang ground-based radar is provided in this paper by comparing the averaged profiles of PR and Fuyang in different regions.
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发布时间：2021-06-10
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