最新刊期
卷 ， 期 1 ， 1999
- 摘要：This paper presents the simulative study of real time calibrated microwave radiometer based on the total power microwave radiometer. The simulation models of every section are built. In the simulative test, the mathematical means of discrete Fast Fourier Transform is used in signal processing. The contradiction of frequency resolving power and the number samples by the large span of frequency range is analyzed and relieved. The real time calibrated microwave radiometer is a new type of microwave radiometer. It can efficiently eliminate the influence of system gain fluctuations and effective system noise fluctuations. Thus, it is more suitable to spaceborne microwave remote sensing. The simulative results in this paper give an important reference to its optimizing design. Also they lay a foundation for the advancement of realizing spaceborne environment debugging.
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发布时间：2021-06-10 - 摘要：Sea ice is an important element affecting heat circulation of the earth. Based on the heat emission of sea ice and sea water, the paper analyzes a 3 layer medium at sea surface used to sense sea ice and derives the following model relating intermediate medium to the received emission brightness temperature: T B=A+Be -CD where A,B and C all depend on polarization, observation angle and frequency of the remote sensing system, they can be deduced from sea ice in situ measurement on ground. The model agrees with propagation features of electromagnetic wave in loss medium and reflects the relationship between the received energy by passive microwave remote sensing system and the propagation distance. In recent years, 4 bands of microwave radiometers were used to measure sea ice on ground （0 degree observation angle） and 3 of them were used in aerial remote sensing, two results are basically in agreement. The fact shows that the model is correct and feasible. Sea ice thickness distribution along the flight line over Liudongwan Gulf and statistical curve relating brightness temperature to ice thickness are given. Several factors affecting measurement and limiting ice thickness identification are pointed out.关键词：sea ice;passive microwave remote sensing;Model
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发布时间：2021-06-10 - 摘要：The research on crops microwave scattering model is developing fast. But, the integrated study of both volume and surface model is still in the beginning stage in China. This paper applies the combined model to the cotton soil media and conducts some exploring works. Microwave scattering in cotton soil media has been calculated from zero, first to second order scattering. The paper analyses major factors which affect the backscattering coefficient. Some valuable conclusions have been drawn. Among these, the incident wave frequency and cotton leaf radius are the major factors. For cotton field scattering in small incident angles （<30°）, the major scattering is from soil surface, when the incident angle is more than 30°, the major scattering is from cotton canopy. It may be helpful for cotton microwave remote sensing monitoring and discrimination.关键词：Cotton field;GRG approximation;Backscattering scattering coefficient
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发布时间：2021-06-10 - 摘要：Based upon the development and flight experiments of the airborne radar altimeter, and according to the characteristics of the signal returned from ocean surface, a spaceborne radar altimeter system is designed. The system operates on pulse limited mode, transmitting pulses are FM Chirp pulses, the returned signal is processed in receiver in frequency domain instead of time domain by adopting “Full De ramp” technique and frequency spectrum analysis method. Adaptive tracker can remove about 75% of the noise power. High pulse repetition rate results in maximum effective number of independent pulses and are best effective in eliminating ocean surface backscatter speckle noise. The main operating modes are desiged: dual resolusion acquisition and tracking mode makes acquisition time of the returned signal within 5 s, calibration mode can assure the designed height precision. The effects to height evaluation of the main noises, i.e. ocean surface backscatter speckle noise and receiver thermal noise, are analyzed. By analyzing the returned signals of several typical sea states, the results have shown that the system height measurement precision can be ±2cm.关键词：Radar altimeter;Operating mode;Height measurement precision
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发布时间：2021-06-10 - 摘要：According to the theory of SAR Imaging of Oceanic surface characteristics, sea surface slicks of different origins can dampen the capillary waves and short gravity waves, and change the roughness of the sea surface and the light reflection characteristics of sea surface. The change of sea surface roughness can be detected using SAR imagery. In this paper, sea surface slicks of different possible origins and their imagery characteristics in oceanic SAR images have been discussed and analyzed. In the present research work, we traced the sea surface slicks in the whole Bohai Bay using ERS 2 SAR imagery, classify the slicks detected in SAR images using statistical method and analyze the possible sources of the different types of slicks.关键词：Sea surface slicks;SAR image;classification
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发布时间：2021-06-10 - 摘要：The technology of Geographic Information System （GIS）, applied to process the spatial information of land resources, provides powerful scientific basis for macro decisions. According to the foreign and domestic studies on the Land Resources Information System （LRIS）, the paper discusses five problems which should be paid great attention to and need better research when the system of this type are established. These problems are as follows: 1. The establishment of synthetic Database Management System, which can be adapted to several types of data, is important in data organization of LRIS. 2. In LRIS, when data is collected the reliability, high accuracy and actuality of data must be taken into account, and the combination of Map, Remote Sensing and Geoinformation is the main means for updating data. 3. Spatial Analysis is the core of LRIS, the design of Fuzzy Spatial Analysis will make the function of spatial analysis more powerful in LRIS. 4. The integration of application models and GIS software is important in the integration of LRIS system, and three kinds of system structures such as Symmetric Configuration, Embedding Configuration and Configuration of Dynamic Linking are adopted to integrate data together in different modules in developing LRIS. 5. The integration of advanced techniques such as GIS, RS, ES and Artificial Intelligence is becoming increasing evident.关键词：Land resources information system;Object oriented database;Fuzzy spatial analysis;System integration
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发布时间：2021-06-10 - 摘要：Based on the evaluated ecological environmental quality of Chinese land resources with Digital Environmental Model （DEM）, the comprehensive evaluated map of the ecological environmental quality of Chinese land resources and the map of population density were worked out. At first, the degree areas constitution and distribution condition of the ecological environmental quality of Chinese land resources were analyzed, the best land resources area of the ecological environmental quality is distributed in south east China; Then the relations between the ecological environmental quality of Chinese land resources and Chinese population distribution were analyzed with relative method and curves. The conclusions are that the substantive relations exist between the ecological environmental quality of Chinese land resources and population; the south east China is the best area of the ecological environmental quality of Chinesse land resources, this area has largest population density and highest used degree of land resources; the west north China is a poor area of the ecological environmental quality of Chinese land resources, this area has smaller population density and lower used degree of land resources.关键词：Digital Environmental Model （DEM）;Land resources;Ecological environmental quality;Density of population
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发布时间：2021-06-10 - 摘要：With the fast development of GIS applications, more and more practical GIS systems have been built, and it is imperative to integrate those systems into a more powerful and convenient system. This article puts forward the concept and framework of GIS integration platform which includes including GIS data integration platform and GIS model integration platform. We first put forward an client/server system architecture as an overall system architecture of GIS integrity platform. By defining Client request, GIS Data Integration Server, GIS Model Integration Server, Application Model Server, and GIS, RS, RDBMS Server, their function and interaction are discussed. In this Architecture, GIS Data Integration Server and GIS Model Integration Server are two key issues to be addressed. As for the GIS data integration platform, a metadata based method for practical concern is suggested. We divide GIS data into four categories: RS image data （Raster）, RS classification data （Vector）, digital map data （vector） and relational data （Attribute）. Each GIS data set registers its metadata information in the platform. Through meta database management system we can link those data into an integrated one by RS image serial number and attribute foreign key. The platform provides GIS information retrieve, GIS model data request and mapping function in integrated, visual and interactive way. As for the model integration platform, We establish a database management system to construct, add, delete or modify GIS model by decompose each model into three levels items which are model level, function level and variable level. Items in each table are standard 3NF compatible, the management system links those relational tables together and provides those functions through relational operation in real time needs. A visual model construction tool is necessary in complex GIS application since it may be lack of off hand model suitable to solve the problem. We provide a GIS visual model construction tool based on the client/server system architecture and relational model based management system.关键词：Geographical information system;Integration platform framework architecture;GIS data integration platform;GIS model integration platform;GIS visual modeling
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发布时间：2021-06-10 - 摘要：With the increasing volumes of remote sensing data, data compression is receiving more and more attention. Adapting to the specialities of remote sensing data the low local correlation and the rich complex texture information, this paper presents an adaptive scalar vector hybrid quantization method for compression based on wavelet transform. According to textural intensity of every block in wavelet transformed high frequency subimage, we classify them into four classes. Compressing the plain block is at high compression ratio, and the textural block at high fidelity, The method enable the balance of the restore error of every block. This method is time efficient by avoiding the codebook training and searching, while surpass the performence of JPEG for single image. By combining with K L transformation, which is a kind of correlation reduction methods, we apply the presented method to multi band remote sensing image, and good results have been obtained.关键词：Wavelet transform;Hybrid quantization;Image compression.
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发布时间：2021-06-10 - 摘要：Almost all the energy directly or indirectly comes from incident solar radiation on the earth. However, the difference of earth’s movement and latitude brings about unique distribution of energy in the temporal and spatial domains. As a results unique distribution of energy leads to great change among atmosphere, ocean, glacier/snow, land surface and creature. In some temporal scale, this kind of influencing significance even has exceeded the effect of the solar activity. In the transfer of mass, energy and momentum, because of the different physical characteristics and roles that land surface has played, it requires us to build up an accurate database of land surface type. A perfect transcendental knowledge is a precondition to derive surface albedo and temperature. Surface albedo and temperature describe the information of inner structure of vegetation, and distribution of energy. Ultimately, they decide how to distribute the energy and mass between the earth’s surface and atmospheric layers. Latent is an important parameter that describes the exchange of energy between land surface and atmosphere. Reliable estimates of latent are essential to significant improvements in the field of GCM. Complementary Relationship （CRAE） areal evapotranspiration models only need meteorological data in the process of calculating latent, some important meteorological data can be derived thorough satellite. Therefore, in this paper, CRAE is applied to the field of remote sensing. Some parameters that CRAE is required for example, surface albedo, temperature is derived completely from NOAA AVHRR data. Penman formula and large scale advection parameter are corrected through the measured data. Finally, farmland and inland water evaporation of North China is calculated by applying CR model.
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发布时间：2021-06-10 - 摘要：With the different view of traditional methods, in the light of the topological theory, this paper studies a new method for converting raster data to vector data. Compared with traditional methods, the new method does not need to pro process the raster image, created topological structure of vector data during the conversion. This method processed raster data row by row just one time, and could fit for large image. It, therefore, has high efficiency high speed, and gives good experimental results.关键词：Raster structure;Vector structure;Transfer;Topological theory
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发布时间：2021-06-10 - 摘要：The disadvantage of Principal component analysis algorithm is presented and a fast approximate Principal component analysis algorithm is studied on the basis of wavelet packet algorithm. The complexity of these two kinds of algorithms are compared. The experiment shows that the algorithm proposed above has obvious advantages in precision and speed.关键词：principal component analysis;Wavelet packet algorithm;Fast approximate Principal component analysis algorithm
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发布时间：2021-06-10 - 摘要：The method of imaging spectral angle mapping （SAM） is one of the main methods of mineral spectra identification in imaging spectra image processing technique, but its application result is not very good. The advantages, disadvantages and their causes are studied and discussed in this paper using clustered analysis of similarity coefficients of lithological lab spectra. The test area is located in the Zhaertai Mountain region of northern China. The imaging spectrometer data were collected using the Medium Resolution Airborne Imaging Spectrometer （MAIS） developed by Chinese Academy of Sciences. The paper emphasizes that a spectrum of rock is non linear mixture of minerals’ spectra that include either selective absorption or non selective absorption, and affection of non selective absorption to result of SAM classification. A simple average image is suggested to use in the lithology mapping technique integrated with SAM image, to solve the problem of “different objects having the same spectra” which is often produced in the classification of imaging spectra angle mapping method, thereby obtaining better lithological mapping results.关键词：Imaging spectra;Lithology mapping
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发布时间：2021-06-10
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