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  • Articles  (37)
  • 2010-2014  (37)
  • 2011  (37)
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  • Articles  (37)
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  • 2010-2014  (37)
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  • 11
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    Modeling the Local Rainfall Effects on Millimeter-Wave Propagation Using Homogeneous Meteorological Areas (2011)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publication Date: 2011-11-01
    Description: The prediction of rain rate is one of the important topics in analyzing wireless communication systems, particularly in the analysis of broadband satellite links operating in the Ku-band (12-18 GHz), K-band (18-26.5 GHz), and Ka-band (26.5-40 GHz). A perfect physical model for the rain attenuation requires some parameters which are not available in most places on the Earth. This letter shows how to use the climatology skills to recognize homogeneous meteorological areas for two different countries and how to generalize the rain-rate attenuation prediction model of one city to another. The proposed method is then compared with the International Telecommunication Union model and the method of moments to confirm the results.
    Print ISSN: 1545-598X
    Electronic ISSN: 1558-0571
    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
    Published by Institute of Electrical and Electronics Engineers (IEEE)
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  • 12
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    Automated Lake Shoreline Mapping at Subpixel Accuracy (2011)
    Institute of Electrical and Electronics Engineers (IEEE)
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    Publication Date: 2011-11-01
    Description: Accurate assessment of lake extent and variation is essential for understanding the global hydrological cycle and necessitates the use of satellite data. The intrinsic scale of lake dynamics is finer than the spatial resolution of available images. Lake change detection requires mapping lake shorelines with high positional accuracy as they are employed for calculating changes in area and volume. There exist many techniques for mapping lake shorelines from multispectral images, and their accuracy decreases as the image spatial resolution degrades. In addition, lake shorelines obtained from images have a zagged appearance, which not only provides an unrealistic representation but also overestimates the lake perimeter. This letter presents a method for subpixel lake shoreline mapping. The approach is used to map subpixel shorelines from Landsat Enhanced Thematic Mapper Plus images acquired in the lake-rich Arctic Coastal Plain of northern Alaska, where lakes dominate the landscape and change significantly over time. High performance of the proposed approach is demonstrated by the agreement of subpixel shorelines with high-resolution QuickBird panchromatic images. The subpixel shorelines estimated by the proposed approach are smooth and lead to precise area estimation and displacement error reduction when compared with the shorelines obtained using image segmentation. The proposed approach has great potential in regional-scale shoreline mapping.
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    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
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  • 13
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    Bayesian Inverse Synthetic Aperture Radar Imaging (2011)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publication Date: 2011-11-01
    Description: In this letter, a novel algorithm of inverse synthetic aperture radar (ISAR) imaging based on Bayesian estimation is proposed, wherein the ISAR imaging joint with phase adjustment is mathematically transferred into signal reconstruction via maximum a posteriori estimation. In the scheme, phase errors are treated as model errors and are overcome in the sparsity-driven optimization regardless of the formats, while data-driven estimation of the statistical parameters for both noise and target is developed, which guarantees the high precision of image generation. Meanwhile, the fast Fourier transform is utilized to implement the solution to image formation, promoting its efficiency effectively. Due to the high denoising capability of the proposed algorithm, high-quality image also could be achieved even under strong noise. The experimental results using simulated and measured data confirm the validity.
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    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
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  • 14
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    Internal Calibration for Stepped-Frequency Chirp SAR Imaging (2011)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publication Date: 2011-11-01
    Description: For synthetic aperture radar imaging, stepped-frequency chirp signals are widely used to obtain high range resolution. One advantage of the approach is the reduction of the instantaneous bandwidth and sampling rate requirements of the radar system. To reconstruct the spectrum of a wideband signal, the amplitude and phase discontinuity between contiguous pulses should be removed. Otherwise, the discontinuity will defocus the range profile and degrade the range resolution. In this letter, a detailed internal calibration technique combined with stepped-frequency mode is proposed to eliminate the discontinuity and thus improve the focusing quality of the final image. The simulation and real raw data experiments are performed to validate the proposed method.
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    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
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  • 15
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    Semisupervised Band Clustering for Dimensionality Reduction of Hyperspectral Imagery (2011)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publication Date: 2011-11-01
    Description: Band clustering is applied to dimensionality reduction of hyperspectral imagery. Different from unsupervised clustering using all the pixels or supervised clustering requiring labeled pixels, the proposed semisupervised band clustering needs class spectral signatures only. After clustering, a cluster selection step is applied to select clusters to be used in the following data analysis. Initial conditions and distance metrics are also investigated to improve the clustering performance. The experimental results show that the proposed algorithm can outperform other existing methods with lower computational cost.
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    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
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  • 16
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    Correlation Coefficients Between Polarization Signatures for Evaluating Polarimetric Information Preservation (2011)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publication Date: 2011-11-01
    Description: In order to evaluate quantitatively the preservation performance of polarimetric information for polarimetric synthetic aperture radar (PolSAR) speckle filters, this letter presents correlation coefficients between the original and the filtered polarimetric data based on the theory of polarization synthesis. The copolarized and the cross-polarized correlation coefficients are furthermore discussed in cases whether the transmitting and receiving radar antennas are characterized by the same or orthogonal polarization state. To show how these coefficients can be exploited in evaluating the preservation of polarimetric information, they are demonstrated with a German Aerospace Center (DLR) Experimental Synthetic Aperture Radar L-band full-polarized image of the Oberpfaffenhofen Test Site Area (DE), Germany, which was obtained on September 30, 2000. Results make evident that the correlation coefficients are efficient to describe quantitatively the performance in preserving polarimetric information for PolSAR speckle filters.
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    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
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  • 17
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    Inverse Profiling via an Effective Linearized Scattering Model and MRF Regularization (2011)
    Institute of Electrical and Electronics Engineers (IEEE)
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    Publication Date: 2011-11-01
    Description: The aim of this letter is to show how a joint adoption of a suitable regularization scheme and a proper rewriting of the traditional electromagnetic scattering equation allows introducing an interesting linear inversion tool which allows achieving nice reconstructions in many cases of practical interest. In particular, an innovative inversion approach which takes definite advantage from the joint use of the Contrast Source-Extended Born model and a Markov-random-field-based regularization scheme is proposed. Numerical examples, confirming accuracy usefulness, are reported and discussed.
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    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
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  • 18
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    Application of Gaussian Mixture Model and Estimator to Radar-Based Weather Parameter Estimations (2011)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publication Date: 2011-11-01
    Description: The estimation of weather parameters such as attenuation and rainfall rates from remotely sensed weather radar data has been based mainly on deterministic regression models. This letter introduces a new Gaussian mixture parameter estimator (GMPE)-based framework to incorporate prior knowledge into this process. The GMPE makes possible a versatile model for parameter estimation under all conditions without compromising accuracy. Observations from dual-polarized and dual-frequency radar sensors can be utilized in the GMPE in a very flexible manner. Simulation examples have demonstrated that the GMPE has better estimation error performance than traditional methods for parameter estimation applications, particularly for noisy observations. The impacts of mixture number and state vector selections in the GMPE are also discussed.
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    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
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  • 19
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    Impact of Gypsum on Electromagnetic Properties of Desert Soils (2011)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publication Date: 2011-11-01
    Description: Radar remote sensing of soil requires an understanding about the electromagnetic properties of soils. Propagation velocities and attenuation rates at ground-penetrating radar frequencies (0.25-4 GHz) were measured as a function of soil moisture content for soils from Iraq and Afghanistan. Soil samples in the study include two with and two without gypsum (CaSO 4 ·2H 2 O) as a major mineral component. When measured at 100°C, volumetric moisture content of gypsum-rich soils ranged from 12% to 24%. In addition to the high moisture content, the propagation velocities were higher than expected, and attenuation rates were lower than expected for soils with moisture contents in this high range. The apparently anomalous relationship between high moisture content and low attenuation rate is explained by the presence and characteristics of gypsum in the soil. Radar signals are not affected by the chemically bound water molecules in gypsum which dehydrates at 100°C. These results show that soil mineralogy is critically important to the interpretation of dielectric properties.
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    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
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  • 20
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    An Automated Approach to Detect Oceanic Eddies From Satellite Remotely Sensed Sea Surface Temperature Data (2011)
    Institute of Electrical and Electronics Engineers (IEEE)
    Details
    Publication Date: 2011-11-01
    Description: Cyclonic (anticyclonic) oceanic eddies drive local upwelling (downwelling), leaving footprints in the sea surface temperature (SST) field as local extremes. Satellite-measured SST images can therefore be used to obtain information of the characteristics of oceanic eddies. Remotely sensed measurements represent very large data sets, both spatially and temporally. Manual eddy detection and analysis are thus practically impossible. In this letter, an automated scheme for eddy detection from remote sensing SST data is presented. The method is based on the analysis of velocity fields derived from SST measurements (thermal-wind velocity field). Using the geometric features of the velocity field, we can identify positions of eddy centers and derive eddy size, intensity, path, and lifetime. The scheme is applied to a realistic remotely sensed SST data set in a strong eddy activity region: Kuroshio Extension region.
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