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Sample records for sar despeckling filters

  1. Despeckling PolSAR images with an adaptive bilateral filter

    Science.gov (United States)

    Liu, Liu; Zhou, Fang; Chen, Jing; Yang, Xuezhi; Jia, Lu; Dong, Zhangyu; Ai, Jiaqiu

    2017-04-01

    An improved bilateral filter with adaptive parameters estimation in space domain and polarimetric domain for polarimetric synthetic aperture radar (PolSAR) image despeckling, named PolSAR adaptive bilateral filtering (PABF), is proposed. On one hand, PABF sets the spatial parameter adaptively according to the local coefficient of variation. On the other hand, the polarimetric parameter is adjusted adaptively on the basis of the noise variance estimated from the convolution between the intensity image and Laplacian template. The experiments performed on simulated and real PolSAR data show that PABF effectively suppresses speckles while maintaining important details of images.

  2. A PolSAR image despeckle filter based on evidence theory

    Science.gov (United States)

    Kharbouche, Saïd

    2010-10-01

    Images issued from a SAR (Synthetic Aperture Radar) sensor are effected by a specific noise called speckle; therefore, many studies have been dedicated to modulate this noise with the aim to be able to reduce its effects. But, studies in the area of polarimetric SAR (PolSAR) images despeckling are still poor and don't take advantage correctly of polarimetric information. In this way, this paper describes an original and efficient method of despeckling PolSAR images in order to improve the visualization and the extraction of planimetric features. The proposed filter, takes into account all polarization modes for each polarization mode despeckling. So, for a pixel in a single polarization mode, the modification of its radiometric value will be supervised by it adjacent pixels in the same polarization mode and also by their equivalent pixels in other polarization modes. Furthermore, to avoid error propagation, the filter will be very cautious in modification of radiometric values in such way that it runs in many iterations modifying the less ambiguous pixels firstly and leaves the rest of the pixels for the next iterations for a possible modification. To combine the information resulting from each polarization mode and make a decision, the proposed filter calls some rules of the Evidence Theory. The experimentation was done on Radarsat-2 images of the Arctic and Quebec regions of Canada, and the results show clearly the benefit and the high performance of this despeckling approach.

  3. A despeckle filter for the Cassini SAR images of Titan's surface

    Science.gov (United States)

    Bratsolis, Emmanuel; Solomonidou, Anezina; Bampasidis, Georgios; Le Mouelic, Stephane; Sotin, Christophe; Coustenis, Athena; Moussas, Xenophon; Kyriakopoulos, Konstantinos

    2010-05-01

    Cassini carries a multimode Ku-band (13.78 GHz) radar instrument designed to probe the surface of Titan and that of other targets in the Saturn system in four operating modes: imaging, altimetry, scatterometry, and radiometry. The Synthetic Aperture Radar (SAR) mode is used at altitudes under ~4000 km, resulting in spatial resolution ranging from ~350 m to >1 km. Images are acquired either left or right of nadir using 2-7 looks. A swath 120-450 km wide is created from 5 antenna beams. SAR coverage is dependent on spacecraft range and orbital geometry. Radar backscatter variations in SAR images can be interpreted in terms of variations of surface slope, near-surface roughness, or near-surface dielectric properties. The images obtained using SAR revealed that Titan has very complex surface (Elachi et al. 2005). A filtering technique is applied to obtain the restored image. One of the major problems hampering the derivation of meaningful texture information from SAR imagery is the speckle noise. It overlays "real" structures and causes gray value variations even in homogeneous parts of the image. Our method is based on probabilistic methods and regards an image as a random element drawn from a prespecified set of possible images. The TSPR (Total Sum Preserving Regularization) filter used here is based on a membrane model Markov random field approximation with a Gaussian conditional probability density function optimized by a synchronous local iterative method. The final form of despeckling gives a sum-preserving regularization for the pixel values of the image. The TSPR method preserves the mean values of local homogeneous regions and decreases the standard deviation up to six times (Bratsolis and Sigelle, 2003). The despeckle filter can be used as intermediate stage for the extraction of meaningful regions that correspond to structural units in the scene or distinguish objects of interest (Bratsolis, 2009). References E. Bratsolis, and M. Sigelle, "Fast SAR Image

  4. Guided SAR image despeckling with probabilistic non local weights

    Science.gov (United States)

    Gokul, Jithin; Nair, Madhu S.; Rajan, Jeny

    2017-12-01

    SAR images are generally corrupted by granular disturbances called speckle, which makes visual analysis and detail extraction a difficult task. Non Local despeckling techniques with probabilistic similarity has been a recent trend in SAR despeckling. To achieve effective speckle suppression without compromising detail preservation, we propose an improvement for the existing Generalized Guided Filter with Bayesian Non-Local Means (GGF-BNLM) method. The proposed method (Guided SAR Image Despeckling with Probabilistic Non Local Weights) replaces parametric constants based on heuristics in GGF-BNLM method with dynamically derived values based on the image statistics for weight computation. Proposed changes make GGF-BNLM method adaptive and as a result, significant improvement is achieved in terms of performance. Experimental analysis on SAR images shows excellent speckle reduction without compromising feature preservation when compared to GGF-BNLM method. Results are also compared with other state-of-the-art and classic SAR depseckling techniques to demonstrate the effectiveness of the proposed method.

  5. SAR Image despeckling via sparse representation

    Science.gov (United States)

    Wang, Zhongmei; Yang, Xiaomei; Zheng, Liang

    2014-11-01

    SAR image despeckling is an active research area in image processing due to its importance in improving the quality of image for object detection and classification.In this paper, a new approach is proposed for multiplicative noise in SAR image removal based on nonlocal sparse representation by dictionary learning and collaborative filtering. First, a image is divided into many patches, and then a cluster is formed by clustering log-similar image patches using Fuzzy C-means (FCM). For each cluster, an over-complete dictionary is computed using the K-SVD method that iteratively updates the dictionary and the sparse coefficients. The patches belonging to the same cluster are then reconstructed by a sparse combination of the corresponding dictionary atoms. The reconstructed patches are finally collaboratively aggregated to build the denoised image. The experimental results show that the proposed method achieves much better results than many state-of-the-art algorithms in terms of both objective evaluation index (PSNR and ENL) and subjective visual perception.

  6. Texture analysis and despeckle of multitemporal SAR images

    Science.gov (United States)

    Alparone, Luciano; Baronti, Stefano; Carla, Roberto

    1998-12-01

    Local-statistics speckle filtering has been extended to multitemporal SAR data by exploiting the temporal correlation of the speckle noise across a set of images of the same scene taken at different times. A recursive nonlinear transformation aimed at decorrelating the data across time, while retaining the multiplicative noise model, is defined from the geometric means and the ratios of couples of spatially overlapped observations. The temporal correlation coefficient (TCC) is estimated from the modes of the distributions of the local variation coefficient Cv computed on transformed couples of images. The images are filtered in the transformed domain and reversely transformed to yield despeckled observations in which seasonal changes are preserved, or even highlighted, and texture analysis is expedited. Tests on four SAR images from repeat-pass ERS-1 corroborate the theoretical assumptions and show the filtering performances of the proposed approach.

  7. The Pixel-similarity Measurement in SAR Image Despeckling

    Directory of Open Access Journals (Sweden)

    Li Guang-ting

    2012-09-01

    Full Text Available The Pixel Relativity (PR measurement of SAR image, which is the key of the despeckling techniques based on weighted average, is researched in three aspects. Firstly, the rationality of ratio PR model is expounded, and two new ratio PR models, which are the LOG-domain Gaussian model and the pixel similarity probability model, are proposed. Meanwhile, the Probability Density Function (PDF of SAR image and the PDF of the ratio between pixels are transformed into ratio PR models. Then, in order to evaluate the four ratio PR models, the weighted maximum likelihood filters are designed using the PR. Finally, a novel method, performed by calibrating the maximum location of the PR model, is introduced to improve the radiation preservation of those models whose maximum do not locate at 1. The effectiveness of the two proposed PR models and the approach to calibrate the maximum location of the PR model, are indicated by the theoretical analysis and experimental comparison.

  8. Despeckle and geographical feature extraction in SAR images by wavelet transform

    Science.gov (United States)

    Gupta, Karunesh K.; Gupta, Rajiv

    This paper presents a method to despeckle Synthetic Aperture Radar (SAR) image, and then extract geographical features in it. In this research work, speckle is reduced by multiscale analysis in wavelet domain. In terms of geographical feature preservation the result shows that the method is better compared to spatial domain filters, such as Lee, Kuan, Frost, Ehfrost, Median, Gamma filters. The geographical features such as roads, airport runways, rivers and other ribbon-like shape structures are detected by the new wavelet-based method as proposed by Yuan Yan Tang. Experimental results show that the proposed method extracts geographical features of different width as well as different gray levels.

  9. Non-local SAR Image Despeckling Based on Similar Pixels Selected

    Directory of Open Access Journals (Sweden)

    Li Guang-ting

    2012-06-01

    Full Text Available Based on the ratio distance pixel-relativity and thresholding pixel-similarity, a modified non-local filter is proposed for SAR image despeckling in this paper. Firstly, the ratio distance pixel-relativity is obtained by transforming the joint probability density function of two pixels. Then, a table of pixel-similarity threshold, as a function of the SAR image look number and neighboring reflectivity ratio, is trained according to the minimum error probability. Finally, the pixel-similarity threshold is applied to select similar pixels from the searching window for the real reflectivity estimation. The proposed approach was verified by synthetic and real SAR images, and was compared with the PPB and LHRS-PRM filters. The visual quality and the quantification comparison show that the proposed approach is excellent not only in the reconstruction of the uniform area, the character of edges, texture, and details, but also with the lower computation complexity.

  10. GENERALIZATION OF RAYLEIGH MAXIMUM LIKELIHOOD DESPECKLING FILTER USING QUADRILATERAL KERNELS

    Directory of Open Access Journals (Sweden)

    S. Sridevi

    2013-02-01

    Full Text Available Speckle noise is the most prevalent noise in clinical ultrasound images. It visibly looks like light and dark spots and deduce the pixel intensity as murkiest. Gazing at fetal ultrasound images, the impact of edge and local fine details are more palpable for obstetricians and gynecologists to carry out prenatal diagnosis of congenital heart disease. A robust despeckling filter has to be contrived to proficiently suppress speckle noise and simultaneously preserve the features. The proposed filter is the generalization of Rayleigh maximum likelihood filter by the exploitation of statistical tools as tuning parameters and use different shapes of quadrilateral kernels to estimate the noise free pixel from neighborhood. The performance of various filters namely Median, Kuwahura, Frost, Homogenous mask filter and Rayleigh maximum likelihood filter are compared with the proposed filter in terms PSNR and image profile. Comparatively the proposed filters surpass the conventional filters.

  11. Despeckle filtering for ultrasound imaging and video II selected applications

    CERN Document Server

    Loizou, Christos P

    2015-01-01

    In ultrasound imaging and video visual perception is hindered by speckle multiplicative noise that degrades the quality. Noise reduction is therefore essential for improving the visual observation quality or as a pre-processing step for further automated analysis, such as image/video segmentation, texture analysis and encoding in ultrasound imaging and video. The goal of the first book (book 1 of 2 books) was to introduce the problem of speckle in ultrasound image and video as well as the theoretical background, algorithmic steps, and the MatlabTM for the following group of despeckle filters:

  12. A despeckle filter for the Cassini synthetic aperture radar images of Titan's surface

    Science.gov (United States)

    Bratsolis, Emmanuel; Bampasidis, Georgios; Solomonidou, Anezina; Coustenis, Athena

    2012-02-01

    Cassini synthetic aperture radar (SAR) images of Titan, the largest satellite of Saturn, reveal surface features with shapes ranging from quasi-circular to more complex ones, interpreted as liquid hydrocarbon deposits assembled in the form of lakes or seas. One of the major problems hampering the derivation of meaningful texture information from SAR imagery is the speckle noise. It overlays real structures and causes gray value variations even in homogeneous parts of the image. We propose a filtering technique which can be applied to obtain restored SAR images. Our technique is based on probabilistic methods and regards an image as a random element drawn from a prespecified set of possible images. The despeckle filter can be used as an intermediate step for the extraction of regions of interest, corresponding to structured units in a given area or distinct objects of interest, such as lake-like features on Titan. This tool can therefore be used, among other, to study seasonal surficial changes of Titan's polar regions. In this study we also present a segmentation technique that allows us to separate the lakes from the local background.

  13. Feature-Based Nonlocal Polarimetric SAR Filtering

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    Xiaoli Xing

    2017-10-01

    Full Text Available Polarimetric synthetic aperture radar (PolSAR images are inherently contaminated by multiplicative speckle noise, which complicates the image interpretation and image analyses. To reduce the speckle effect, several adaptive speckle filters have been developed based on the weighted average of the similarity measures commonly depending on the model or probability distribution, which are often affected by the distribution parameters and modeling texture components. In this paper, a novel filtering method introduces the coefficient of variance ( CV and Pauli basis (PB to measure the similarity, and the two features are combined with the framework of the nonlocal mean filtering. The CV is used to describe the complexity of various scenes and distinguish the scene heterogeneity; moreover, the Pauli basis is able to express the polarimetric information in PolSAR image processing. This proposed filtering combines the CV and Pauli basis to improve the estimation accuracy of the similarity weights. Then, the similarity of the features is deduced according to the test statistic. Subsequently, the filtering is proceeded by using the nonlocal weighted estimation. The performance of the proposed filter is tested with the simulated images and real PolSAR images, which are acquired by AIRSAR system and ESAR system. The qualitative and quantitative experiments indicate the validity of the proposed method by comparing with the widely-used despeckling methods.

  14. Digital Path Approach Despeckle Filter for Ultrasound Imaging and Video

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    Marek Szczepański

    2017-01-01

    Full Text Available We propose a novel filtering technique capable of reducing the multiplicative noise in ultrasound images that is an extension of the denoising algorithms based on the concept of digital paths. In this approach, the filter weights are calculated taking into account the similarity between pixel intensities that belongs to the local neighborhood of the processed pixel, which is called a path. The output of the filter is estimated as the weighted average of pixels connected by the paths. The way of creating paths is pivotal and determines the effectiveness and computational complexity of the proposed filtering design. Such procedure can be effective for different types of noise but fail in the presence of multiplicative noise. To increase the filtering efficiency for this type of disturbances, we introduce some improvements of the basic concept and new classes of similarity functions and finally extend our techniques to a spatiotemporal domain. The experimental results prove that the proposed algorithm provides the comparable results with the state-of-the-art techniques for multiplicative noise removal in ultrasound images and it can be applied for real-time image enhancement of video streams.

  15. Despeckle filtering software toolbox for ultrasound imaging of the common carotid artery.

    Science.gov (United States)

    Loizou, Christos P; Theofanous, Charoula; Pantziaris, Marios; Kasparis, Takis

    2014-04-01

    Ultrasound imaging of the common carotid artery (CCA) is a non-invasive tool used in medicine to assess the severity of atherosclerosis and monitor its progression through time. It is also used in border detection and texture characterization of the atherosclerotic carotid plaque in the CCA, the identification and measurement of the intima-media thickness (IMT) and the lumen diameter that all are very important in the assessment of cardiovascular disease (CVD). Visual perception, however, is hindered by speckle, a multiplicative noise, that degrades the quality of ultrasound B-mode imaging. Noise reduction is therefore essential for improving the visual observation quality or as a pre-processing step for further automated analysis, such as image segmentation of the IMT and the atherosclerotic carotid plaque in ultrasound images. In order to facilitate this preprocessing step, we have developed in MATLAB(®) a unified toolbox that integrates image despeckle filtering (IDF), texture analysis and image quality evaluation techniques to automate the pre-processing and complement the disease evaluation in ultrasound CCA images. The proposed software, is based on a graphical user interface (GUI) and incorporates image normalization, 10 different despeckle filtering techniques (DsFlsmv, DsFwiener, DsFlsminsc, DsFkuwahara, DsFgf, DsFmedian, DsFhmedian, DsFad, DsFnldif, DsFsrad), image intensity normalization, 65 texture features, 15 quantitative image quality metrics and objective image quality evaluation. The software is publicly available in an executable form, which can be downloaded from http://www.cs.ucy.ac.cy/medinfo/. It was validated on 100 ultrasound images of the CCA, by comparing its results with quantitative visual analysis performed by a medical expert. It was observed that the despeckle filters DsFlsmv, and DsFhmedian improved image quality perception (based on the expert's assessment and the image texture and quality metrics). It is anticipated that the

  16. Speckle Reduction for Ultrasonic Imaging Using Frequency Compounding and Despeckling Filters along with Coded Excitation and Pulse Compression

    Directory of Open Access Journals (Sweden)

    Joshua S. Ullom

    2012-01-01

    Full Text Available A method for improving the contrast-to-noise ratio (CNR while maintaining the −6 dB axial resolution of ultrasonic B-mode images is proposed. The technique proposed is known as eREC-FC, which enhances a recently developed REC-FC technique. REC-FC is a combination of the coded excitation technique known as resolution enhancement compression (REC and the speckle-reduction technique frequency compounding (FC. In REC-FC, image CNR is improved but at the expense of a reduction in axial resolution. However, by compounding various REC-FC images made from various subband widths, the tradeoff between axial resolution and CNR enhancement can be extended. Further improvements in CNR can be obtained by applying postprocessing despeckling filters to the eREC-FC B-mode images. The despeckling filters evaluated were the following: median, Lee, homogeneous mask area, geometric, and speckle-reducing anisotropic diffusion (SRAD. Simulations and experimental measurements were conducted with a single-element transducer (f/2.66 having a center frequency of 2.25 MHz and a −3 dB bandwidth of 50%. In simulations and experiments, the eREC-FC technique resulted in the same axial resolution that would be typically observed with conventional excitation with a pulse. Moreover, increases in CNR of 348% were obtained in experiments when comparing eREC-FC with a Lee filter to conventional pulsing methods.

  17. SAR Image Enhancement using Particle Filters

    Data.gov (United States)

    National Aeronautics and Space Administration — In this paper, we propose a novel approach to reduce the noise in Synthetic Aperture Radar (SAR) images using particle filters. Interpretation of SAR images is a...

  18. Multiplier-free filters for wideband SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Christensen, Erik Lintz

    2001-01-01

    This paper derives a set of parameters to be optimized when designing filters for digital demodulation and range prefiltering in SAR systems. Aiming at an implementation in field programmable gate arrays (FPGAs), an approach for the design of multiplier-free filters is outlined. Design results...

  19. A filtering framework for SAR data based on nongaussian statistics and pixel clustering

    Science.gov (United States)

    Cristea, Anca; Doulgeris, Anthony P.; Eltoft, Torbjørn

    2017-10-01

    We present a filtering framework based on a new statistical model for Single-Look Complex (SLC) Synthetic Aperture Radar (SAR) data, the Scaled Normal-Inverse Gaussian (SNIG). The real and imaginary parts of the SLC image are modeled as mixtures of SNIGs, and the clustering of the mixture components is conducted using a Stochastic Expectation-Maximization (SEM) algorithm. Model parameters are associated to each pixel according to its class, thus producing parametric images of the entire scene. A closed-form Maxmum A Posteriori (MAP) filter then delivers a de-speckled estimate of the image. The method is tested on RADARSAT-2 data, HV polarization, representing images of icebergs surrounded by ocean water off the coast of the Hopen Island (Svalbard archipelago). Post-processing, the iceberg Contrast-to-Noise Ratio (CNR) defined relative to the open water clutter is improved compared to Single-Look Intensity (SLI) image, increasing from a value of 11 to a value of 30 for one of the targets, and the Coefficient of Variation (CV) of the clutter is reduced to a fraction of 0.01 compared to the same reference. We conclude that the proposed method shows potential for improving iceberg detection in open water.

  20. Speckle Filtering of Polarimetric SAR Interferometry Data

    Science.gov (United States)

    Lee, J.-S.; Cloude, S.; Grunes, M. R.; Papathanassiou, K.

    2003-04-01

    Recently, polarimetric SAR interferometry has generated much interest for forest applications. Tree heights and ground topography can be extracted based on interferometric coherence using a random volume over ground coherent mixture model. The coherence estimation is of paramount importance for the accuracy of tree height estimation. The coherence (or correlation coefficient) is a statistical average of neighboring pixels of similar scattering characteristics. The commonly used algorithm is the boxcar filter, which has the deficiency of indiscriminate averaging of neighboring pixels. The result is that coherence values are lower than they should be. In this paper, we propose a new algorithm to improve the accuracy in the coherence estimation based on speckle filtering of the 6x6 polarimetric interferometry matrix. Simulated images are used to verify the effectiveness of this algorithm. L-Band DLR ESAR data are used to demonstrate the improved accuracy in coherence and in tree height estimation.

  1. Speckle filtering in satellite SAR change detection imagery

    NARCIS (Netherlands)

    Dekker, R.J.

    1998-01-01

    Repeat-pass Synthetic Aperture Radar (SAR) imagery is useful for change detection. A disadvantage of SAR is the system-inherent speckle noise. This can be reduced by filtering. Various filter types and methods are described in the literature, but not one fits the speckle noise in change detection

  2. Multi-look polarimetric SAR image filtering using simulated annealing

    DEFF Research Database (Denmark)

    Schou, Jesper

    2000-01-01

    Based on a previously published algorithm capable of estimating the radar cross-section in synthetic aperture radar (SAR) intensity images, a new filter is presented utilizing multi-look polarimetric SAR images. The underlying mean covariance matrix is estimated from the observed sample covariance...... matrices, and by applying a set of small orientation-dependent filters in an iterative scheme, the input image becomes highly filtered while maintaining most of the structures in the scene. Results using multi-look polarimetric C-band data from the Danish airborne polarimetric SAR, EMISAR, are presented....

  3. Influence of Speckle Filtering on Polarimetric SAR Data Classification

    Science.gov (United States)

    Shitole, Sanjay; Rao, Y. S.; Mohan, B. Krishna

    2013-08-01

    PolSAR data without speckle reduction provide insufficient accuracy for the segmentation and classification. Fully Polarimetric ALOS PALSAR and Radarsat-2 data acquired over Mumbai, India are used to test the effect of speckle filtering on the classification. Wishart supervised classifier algorithm is used for classification of the filtered and unfiltered data. Boxcar, Refined Lee, Lopez, IDAN, Improved Sigma and newly introduced Sequential Filter are analysed for improvement of classification accuracy. Selection of the most suitable moving window size of speckle reducing algorithms is an important step during speckle filtering. Boxcar and Refined Lee filters are used to test the effect of speckle filtering on classification with varying moving window size of the filter. Boxcar filter has a good noise smoothing capability. Speckle in the image can be minimized by increasing size of scanning window in the process of speckle reduction. However, this undiscriminating averaging using Boxcar filter causes a resolution loss in the vicinity of sharp edges and point targets in the image. As the edges in the image need to be maintained, well known Kohonens Self-Organizing Feature Map (SOFM) is used for this purpose.

  4. Single-Chip FPGA Azimuth Pre-Filter for SAR

    Science.gov (United States)

    Gudim, Mimi; Cheng, Tsan-Huei; Madsen, Soren; Johnson, Robert; Le, Charles T-C; Moghaddam, Mahta; Marina, Miguel

    2005-01-01

    A field-programmable gate array (FPGA) on a single lightweight, low-power integrated-circuit chip has been developed to implement an azimuth pre-filter (AzPF) for a synthetic-aperture radar (SAR) system. The AzPF is needed to enable more efficient use of data-transmission and data-processing resources: In broad terms, the AzPF reduces the volume of SAR data by effectively reducing the azimuth resolution, without loss of range resolution, during times when end users are willing to accept lower azimuth resolution as the price of rapid access to SAR imagery. The data-reduction factor is selectable at a decimation factor, M, of 2, 4, 8, 16, or 32 so that users can trade resolution against processing and transmission delays. In principle, azimuth filtering could be performed in the frequency domain by use of fast-Fourier-transform processors. However, in the AzPF, azimuth filtering is performed in the time domain by use of finite-impulse-response filters. The reason for choosing the time-domain approach over the frequency-domain approach is that the time-domain approach demands less memory and a lower memory-access rate. The AzPF operates on the raw digitized SAR data. The AzPF includes a digital in-phase/quadrature (I/Q) demodulator. In general, an I/Q demodulator effects a complex down-conversion of its input signal followed by low-pass filtering, which eliminates undesired sidebands. In the AzPF case, the I/Q demodulator takes offset video range echo data to the complex baseband domain, ensuring preservation of signal phase through the azimuth pre-filtering process. In general, in an SAR I/Q demodulator, the intermediate frequency (fI) is chosen to be a quarter of the range-sampling frequency and the pulse-repetition frequency (fPR) is chosen to be a multiple of fI. The AzPF also includes a polyphase spatial-domain pre-filter comprising four weighted integrate-and-dump filters with programmable decimation factors and overlapping phases. To prevent aliasing of signals

  5. Noise Removal in SAR Images using Orthonormal Ridgelet Transform

    OpenAIRE

    A. Ravi,; Dr. P.V.Naganjaneyulu

    2015-01-01

    Development in the field of image processing for reducing speckle noise from digital images/satellite images is a challenging task for image processing applications. Previously many algorithms were proposed to de-speckle the noise in digital images. Here in this article we are presenting experimental results on de-speckling of Synthetic Aperture RADAR (SAR) images. SAR images have wide applications in remote sensing and mapping the surfaces of all planets. SAR can also be implemen...

  6. Learnable despeckling framework for optical coherence tomography images

    Science.gov (United States)

    Adabi, Saba; Rashedi, Elaheh; Clayton, Anne; Mohebbi-Kalkhoran, Hamed; Chen, Xue-wen; Conforto, Silvia; Nasiriavanaki, Mohammadreza

    2018-01-01

    Optical coherence tomography (OCT) is a prevalent, interferometric, high-resolution imaging method with broad biomedical applications. Nonetheless, OCT images suffer from an artifact called speckle, which degrades the image quality. Digital filters offer an opportunity for image improvement in clinical OCT devices, where hardware modification to enhance images is expensive. To reduce speckle, a wide variety of digital filters have been proposed; selecting the most appropriate filter for an OCT image/image set is a challenging decision, especially in dermatology applications of OCT where a different variety of tissues are imaged. To tackle this challenge, we propose an expandable learnable despeckling framework, we call LDF. LDF decides which speckle reduction algorithm is most effective on a given image by learning a figure of merit (FOM) as a single quantitative image assessment measure. LDF is learnable, which means when implemented on an OCT machine, each given image/image set is retrained and its performance is improved. Also, LDF is expandable, meaning that any despeckling algorithm can easily be added to it. The architecture of LDF includes two main parts: (i) an autoencoder neural network and (ii) filter classifier. The autoencoder learns the FOM based on several quality assessment measures obtained from the OCT image including signal-to-noise ratio, contrast-to-noise ratio, equivalent number of looks, edge preservation index, and mean structural similarity index. Subsequently, the filter classifier identifies the most efficient filter from the following categories: (a) sliding window filters including median, mean, and symmetric nearest neighborhood, (b) adaptive statistical-based filters including Wiener, homomorphic Lee, and Kuwahara, and (c) edge preserved patch or pixel correlation-based filters including nonlocal mean, total variation, and block matching three-dimensional filtering.

  7. A Network Inversion Filter combining GNSS and InSAR for tectonic slip modeling

    Science.gov (United States)

    Bekaert, D. P.; Segall, P.; Wright, T. J.; Hooper, A. J.

    2016-12-01

    Time-dependent slip modeling can be a powerful tool to improve our understanding of the interaction of earthquake cycle processes such as interseismic, coseismic, postseismic, and aseismic slip. Interferometric Synthetic Aperture Radar (InSAR) observations allow us to model slip at depth with a higher spatial resolution than when using GNSS alone. Typically the temporal resolution of InSAR has been limited. However, the recent generation of SAR satellites including Sentinel-1, COSMO-SkyMED, and RADARSAT-2 permits the use of InSAR for time-dependent slip modeling, at intervals of a few days when combined. The increasing amount of SAR data makes a simultaneous data inversion of all epochs challenging. Here, we expanded the original Network Inversion Filter (Segall and Matthews, 1997) to include InSAR observations of surface displacements in addition to GNSS. In the NIF framework, geodetic observations are limited to those of a given epoch, where a physical model describes the slip evolution over time. The combination of the Kalman forward filtering and backward smoothing allows all geodetic observations to constrain the complete observation period. Combining GNSS and InSAR allows us to model time-dependent slip at an unprecedented spatial resolution. We validate the approach with a simulation of the 2006 Guerrero slow slip event. In our study, we emphasize the importance of including the InSAR covariance information, and demonstrate that InSAR provides an additional constraint on the spatial extent of the slow slip. References: Segall, P., and M. Matthews (1997), Time dependent inversion of geodetic data, J. Geophys. Res., 102 (B10), 22,391 - 22,409, doi:10.1029/97JB01795. Bekaert, D., P. Segall, T.J. Wright, and A. Hooper (2016), A Network Inversion Filter combining GNSS and InSAR for tectonic slip modeling, JGR, doi:10.1002/2015JB012638 (open access).

  8. A Method of SAR Target Recognition Based on Gabor Filter and Local Texture Feature Extraction

    Directory of Open Access Journals (Sweden)

    Wang Lu

    2015-12-01

    Full Text Available This paper presents a novel texture feature extraction method based on a Gabor filter and Three-Patch Local Binary Patterns (TPLBP for Synthetic Aperture Rader (SAR target recognition. First, SAR images are processed by a Gabor filter in different directions to enhance the significant features of the targets and their shadows. Then, the effective local texture features based on the Gabor filtered images are extracted by TPLBP. This not only overcomes the shortcoming of Local Binary Patterns (LBP, which cannot describe texture features for large scale neighborhoods, but also maintains the rotation invariant characteristic which alleviates the impact of the direction variations of SAR targets on recognition performance. Finally, we use an Extreme Learning Machine (ELM classifier and extract the texture features. The experimental results of MSTAR database demonstrate the effectiveness of the proposed method.

  9. Non-local total variation method for despeckling of ultrasound images

    Science.gov (United States)

    Feng, Jianbin; Ding, Mingyue; Zhang, Xuming

    2014-03-01

    Despeckling of ultrasound images, as a very active topic research in medical image processing, plays an important or even indispensable role in subsequent ultrasound image processing. The non-local total variation (NLTV) method has been widely applied to denoising images corrupted by Gaussian noise, but it cannot provide satisfactory restoration results for ultrasound images corrupted by speckle noise. To address this problem, a novel non-local total variation despeckling method is proposed for speckle reduction. In the proposed method, the non-local gradient is computed on the images restored by the optimized Bayesian non-local means (OBNLM) method and it is introduced into the total variation method to suppress speckle in ultrasound images. Comparisons of the restoration performance are made among the proposed method and such state-of-the-art despeckling methods as the squeeze box filter (SBF), the non-local means (NLM) method and the OBNLM method. The quantitative comparisons based on synthetic speckled images show that the proposed method can provide higher Peak signal-to-noise ratio (PSNR) and structure similarity (SSIM) than compared despeckling methods. The subjective visual comparisons based on synthetic and real ultrasound images demonstrate that the proposed method outperforms other compared algorithms in that it can achieve better performance of noise reduction, artifact avoidance, edge and texture preservation.

  10. SAR Interferogram Filtering of Shearlet Domain Based on Interferometric Phase Statistics

    Directory of Open Access Journals (Sweden)

    Yonghong He

    2017-02-01

    Full Text Available This paper presents a new filtering approach for Synthetic Aperture Radar (SAR interferometric phase noise reduction in the shearlet domain, depending on the coherent statistical characteristics. Shearlets provide a multidirectional and multiscale decomposition that have advantages over wavelet filtering methods when dealing with noisy phase fringes. Phase noise in SAR interferograms is directly related to the interferometric coherence and the look number of the interferogram. Therefore, an optimal interferogram filter should incorporate information from both of them. The proposed method combines the phase noise standard deviation with the shearlet transform. Experimental results show that the proposed method can reduce the interferogram noise while maintaining the spatial resolution, especially in areas with low coherence.

  11. Calibration of a Land Subsidence Model Using InSAR Data via the Ensemble Kalman Filter.

    Science.gov (United States)

    Li, Liangping; Zhang, Meijing; Katzenstein, Kurt

    2017-05-23

    The application of interferometric synthetic aperture radar (InSAR) has been increasingly used to improve capabilities to model land subsidence in hydrogeologic studies. A number of investigations over the last decade show how spatially detailed time-lapse images of ground displacements could be utilized to advance our understanding for better predictions. In this work, we use simulated land subsidences as observed measurements, mimicking InSAR data to inversely infer inelastic specific storage in a stochastic framework. The inelastic specific storage is assumed as a random variable and modeled using a geostatistical method such that the detailed variations in space could be represented and also that the uncertainties of both characterization of specific storage and prediction of land subsidence can be assessed. The ensemble Kalman filter (EnKF), a real-time data assimilation algorithm, is used to inversely calibrate a land subsidence model by matching simulated subsidences with InSAR data. The performance of the EnKF is demonstrated in a synthetic example in which simulated surface deformations using a reference field are assumed as InSAR data for inverse modeling. The results indicate: (1) the EnKF can be used successfully to calibrate a land subsidence model with InSAR data; the estimation of inelastic specific storage is improved, and uncertainty of prediction is reduced, when all the data are accounted for; and (2) if the same ensemble is used to estimate Kalman gain, the analysis errors could cause filter divergence; thus, it is essential to include localization in the EnKF for InSAR data assimilation. © 2017, National Ground Water Association.

  12. Shadow Probability of Detection and False Alarm for Median-Filtered SAR Imagery

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). ISR Analysis and Applications Dept.; Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). ISR Mission Engineering Dept.; Miller, John A. [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States). Mission Systems; Bishop, Edward E. [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States). Mission Systems; Horndt, Volker [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States). Mission Systems

    2014-06-01

    Median filtering reduces speckle in synthetic aperture radar (SAR) imagery while preserving edges, at the expense of coarsening the resolution, by replacing the center pixel of a sliding window by the median value. For shadow detection, this approach helps distinguish shadows from clutter more easily, while preserving shadow shape delineations. However, the nonlinear operation alters the shadow and clutter distributions and statistics, which must be taken into consideration when computing probability of detection and false alarm metrics. Depending on system parameters, median filtering can improve probability of detection and false alarm by orders of magnitude. Herein, we examine shadow probability of detection and false alarm in a homogeneous, ideal clutter background after median filter post-processing. Some comments on multi-look processing effects with and without median filtering are also made.

  13. Enhancement of SAR images using fuzzy shrinkage technique in ...

    Indian Academy of Sciences (India)

    Speckle degrades the features in the image and reduces the ability of a human observer to resolve fine detail, hence despeckling is very much required for SAR images. This paper presents speckle noise reduction in SAR images using a combination of curvelet and fuzzy logic technique to restore speckle-affected images.

  14. Filtering and segmentation of the Cassini synthetic aperture radar images on Titan

    Science.gov (United States)

    Bratsolis, E.; Bampasidis, G.; Solomonidou, A.; Coustenis, A.; Hirtzig, M.

    2011-10-01

    A filtering technique is applied to obtain the restored synthetic aperture radar (SAR) images. One of the major problems hampering the derivation of meaningful texture information from SAR imagery is the speckle noise. It overlays "real" structures and causes gray value variations even in homogeneous parts of the image. Our method, the TSPR (total sum preserving regularization) filter, is based on probabilistic methods and regards an image as a random element drawn from a prespecified set of possible images optimized by a synchronous local iterative method. The despeckle filter can be used as intermediate stage for the extraction of meaningful regions that correspond to structural units in the scene or distinguish objects of interest like lakes, drainage networks, equatorial dunes or impact craters, where different textures appear.

  15. Enhancing DInSAR capabilities for landslide monitoring by applying GIS-based multicriteria filtering analysis

    Science.gov (United States)

    Beyene, F.; Knospe, S.; Busch, W.

    2015-04-01

    Landslide detection and monitoring remain difficult with conventional differential radar interferometry (DInSAR) because most pixels of radar interferograms around landslides are affected by different error sources. These are mainly related to the nature of high radar viewing angles and related spatial distortions (such as overlays and shadows), temporal decorrelations owing to vegetation cover, and speed and direction of target sliding masses. On the other hand, GIS can be used to integrate spatial datasets obtained from many sources (including radar and non-radar sources). In this paper, a GRID data model is proposed to integrate deformation data derived from DInSAR processing with other radar origin data (coherence, layover and shadow, slope and aspect, local incidence angle) and external datasets collected from field study of landslide sites and other sources (geology, geomorphology, hydrology). After coordinate transformation and merging of data, candidate landslide representing pixels of high quality radar signals were filtered out by applying a GIS based multicriteria filtering analysis (GIS-MCFA), which excludes grid points in areas of shadow and overlay, low coherence, non-detectable and non-landslide deformations, and other possible sources of errors from the DInSAR data processing. At the end, the results obtained from GIS-MCFA have been verified by using the external datasets (existing landslide sites collected from fieldworks, geological and geomorphologic maps, rainfall data etc.).

  16. Enhancement of SAR Ship Wake Image Based on FABEMD and Goldstein Filter

    Directory of Open Access Journals (Sweden)

    Zhang Wen-yi

    2012-12-01

    Full Text Available Enhanced SAR ship wake images with blur Kelvin wakes and reserved turbulent wakes are very important to the inversions of ship and motion parameters. This paper applies the Fast and Adaptive Bidimensional Empirical Mode Decomposition (FABEMD to decompose the SAR ship wake image into Kelvin wakes, turbulent wakes and other multiscale features, which enhances the gray intensity and spectrum contrast of Kelvin wakes to other features. Based on the FABEMD, a modified Goldstein interferogram filter is developed to further enhance the Kelvin wakes. Moreover, the moment invariants are introduced to evaluate the enhancement. Therefore, the Kelvin wakes are dramatically enhanced and the turbulent wakes are reserved. Algorithm analysis, experiments, subjective and objective evaluations show the reasonable efficiency and capabilities.

  17. Effects of range bin shape and Doppler filter response in a digital SAR data processor

    Science.gov (United States)

    Griffin, C. R.

    1978-01-01

    In calibrating the backscatter coefficient obtained with an imaging synthetic aperture radar (SAR) system to determine absolute values of radar cross-section and reflectivity it is common practice to use a target of known radar cross-section placed within the scene. A corner reflector acts as a point target, but the return from it may not be centered in the resolution cell. It is important, for accurate calibration, to perform straddling corrections based on the range bin and Doppler filter response curves.

  18. Filtering of Interferometric SAR Phase Images as a Fuzzy Matching-Pursuit Blind Estimation

    Directory of Open Access Journals (Sweden)

    Luciano Alparone

    2005-12-01

    Full Text Available We present an original application of fuzzy logic to restoration of phase images from interferometric synthetic aperture radar (InSAR, which are affected by zero-mean uncorrelated noise, whose variance depends on the underlying coherence, thereby yielding a nonstationary random noise process. Spatial filtering of the phase noise is recommended, either before phase unwrapping is accomplished, or simultaneously with it. In fact, phase unwrapping basically relies on a smoothness constraint of the phase field, which is severely hampered by the noise. Space-varying linear MMSE estimation is stated as a problem of matching pursuit, in which the estimator is obtained as an expansion in series of a finite number of prototype estimators, fitting the spatial features of the different statistical classes encountered, for example, fringes and steep slope areas. Such estimators are calculated in a fuzzy fashion through an automatic training procedure. The space-varying coefficients of the expansion are stated as degrees of fuzzy membership of a pixel to each of the estimators. Neither a priori knowledge on the noise variance is required nor particular signal and noise models are assumed. Filtering performances on simulated phase images show a steady SNR improvement over conventional box filtering. Applications of the proposed filter to interferometric phase images demonstrate a superior ability of restoring fringes yet preserving their discontinuities, together with an effective noise smoothing performance, irrespective of locally varying coherence characteristics.

  19. Noise Removal in SAR Images using Orthonormal Ridgelet Transform

    Directory of Open Access Journals (Sweden)

    A. Ravi,

    2015-05-01

    Full Text Available Development in the field of image processing for reducing speckle noise from digital images/satellite images is a challenging task for image processing applications. Previously many algorithms were proposed to de-speckle the noise in digital images. Here in this article we are presenting experimental results on de-speckling of Synthetic Aperture RADAR (SAR images. SAR images have wide applications in remote sensing and mapping the surfaces of all planets. SAR can also be implemented as "inverse SAR" by observing a moving target over a substantial time with a stationary antenna. Hence denoising of SAR images is an essential task for viewing the information. Here we introduce a transformation technique called ―Ridgelet‖, which is an extension level of wavelet. Ridgelet analysis can be done in the similar way how wavelet analysis was done in the Radon domain as it translates singularities along lines into point singularities under different frequencies. Simulation results were show cased for proving that proposed work is more reliable than compared to other despeckling processes, and the quality of de-speckled image is measured in terms of Peak Signal to Noise Ratio and Mean Square Error.

  20. Despeckling of Medical Ultrasound Images

    Science.gov (United States)

    Michailovich, Oleg V.; Tannenbaum, Allen

    2013-01-01

    Speckle noise is an inherent property of medical ultrasound imaging, and it generally tends to reduce the image resolution and contrast, thereby reducing the diagnostic value of this imaging modality. As a result, speckle noise reduction is an important prerequisite, whenever ultrasound imaging is used for tissue characterization. Among the many methods that have been proposed to perform this task, there exists a class of approaches that use a multiplicative model of speckled image formation and take advantage of the logarithmical transformation in order to convert multiplicative speckle noise into additive noise. The common assumption made in a dominant number of such studies is that the samples of the additive noise are mutually uncorrelated and obey a Gaussian distribution. The present study shows conceptually and experimentally that this assumption is oversimplified and unnatural. Moreover, it may lead to inadequate performance of the speckle reduction methods. The study introduces a simple preprocessing procedure, which modifies the acquired radio-frequency images (without affecting the anatomical information they contain), so that the noise in the log-transformation domain becomes very close in its behavior to a white Gaussian noise. As a result, the preprocessing allows filtering methods based on assuming the noise to be white and Gaussian, to perform in nearly optimal conditions. The study evaluates performances of three different, nonlinear filters—wavelet denoising, total variation filtering, and anisotropic diffusion—and demonstrates that, in all these cases, the proposed preprocessing significantly improves the quality of resultant images. Our numerical tests include a series of computer-simulated and in vivo experiments. PMID:16471433

  1. Image enhancements of Landsat 8 (OLI) and SAR data for preliminary landslide identification and mapping applied to the central region of Kenya

    Science.gov (United States)

    Mwaniki, M. W.; Kuria, D. N.; Boitt, M. K.; Ngigi, T. G.

    2017-04-01

    Image enhancements lead to improved performance and increased accuracy of feature extraction, recognition, identification, classification and hence change detection. This increases the utility of remote sensing to suit environmental applications and aid disaster monitoring of geohazards involving large areas. The main aim of this study was to compare the effect of image enhancement applied to synthetic aperture radar (SAR) data and Landsat 8 imagery in landslide identification and mapping. The methodology involved pre-processing Landsat 8 imagery, image co-registration, despeckling of the SAR data, after which Landsat 8 imagery was enhanced by Principal and Independent Component Analysis (PCA and ICA), a spectral index involving bands 7 and 4, and using a False Colour Composite (FCC) with the components bearing the most geologic information. The SAR data were processed using textural and edge filters, and computation of SAR incoherence. The enhanced spatial, textural and edge information from the SAR data was incorporated to the spectral information from Landsat 8 imagery during the knowledge based classification. The methodology was tested in the central highlands of Kenya, characterized by rugged terrain and frequent rainfall induced landslides. The results showed that the SAR data complemented Landsat 8 data which had enriched spectral information afforded by the FCC with enhanced geologic information. The SAR classification depicted landslides along the ridges and lineaments, important information lacking in the Landsat 8 image classification. The success of landslide identification and classification was attributed to the enhanced geologic features by spectral, textural and roughness properties.

  2. Linear Features’ Detection in SAR Images Using Fuzzy Edge Detector (FED)

    Science.gov (United States)

    2000-10-01

    together with dissimilarity measure D4 constitute two promising edge detection • ,jI tools for SAR images, as they incorporate despeckling properties...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO10840 TITLE: Linear Features’ Detection in SAR Images Using Fuzzy Edge...report: ADPO10816 thru ADPO10842 UNCLASSIFIED 49-1 Linear features’ detection in SAR images using Fuzzy Edge Detector (FED) Alexandros Dimoun’ 2

  3. Image Enhancement and Speckle Reduction of Full Polarimetric SAR Data by Gaussian Markov Random Field

    Science.gov (United States)

    Mahdian, M.; Motagh, M.; Akbari, V.

    2013-09-01

    In recent years, the use of Polarimetric Synthetic Aperture Radar (PolSAR) data in different applications dramatically has been increased. In SAR imagery an interference phenomenon with random behavior exists which is called speckle noise. The interpretation of data encounters some troubles due to the presence of speckle which can be considered as a multiplicative noise affecting all coherent imaging systems. Indeed, speckle degrade radiometric resolution of PolSAR images, therefore it is needful to perform speckle filtering on the SAR data type. Markov Random Field (MRF) has proven to be a powerful method for drawing out eliciting contextual information from remotely sensed images. In the present paper, a probability density function (PDF), which is fitted well with the PolSAR data based on the goodness-of-fit test, is first obtained for the pixel-wise analysis. Then the contextual smoothing is achieved with the MRF method. This novel speckle reduction method combines an advanced statistical distribution with spatial contextual information for PolSAR data. These two parts of information are combined based on weighted summation of pixel-wise and contextual models. This approach not only preserves edge information in the images, but also improves signal-to-noise ratio of the results. The method maintains the mean value of original signal in the homogenous areas and preserves the edges of features in the heterogeneous regions. Experiments on real medium resolution ALOS data from Tehran, and also high resolution full polarimetric SAR data over the Oberpfaffenhofen test-site in Germany, demonstrate the effectiveness of the algorithm compared with well-known despeckling methods.

  4. A Network Inversion Filter combining GNSS and InSAR for tectonic slip modeling

    OpenAIRE

    Bekaert, D.; Segall, P; Wright, TJ; Hooper, A.

    2016-01-01

    Studies of the earthquake cycle benefit from long-term time-dependent slip modeling, as it can be a powerful means to improve our understanding on the interaction of earthquake cycle processes such as interseismic, coseismic, postseismic, and aseismic slip. Observations from Interferometric Synthetic Aperture Radar (InSAR) allow us to model slip at depth with a higher spatial resolution than when using GNSS alone. While the temporal resolution of InSAR has typically been limited, the recent f...

  5. Space-Variant Post-Filtering for Wavefront Curvature Correction in Polar-Formatted Spotlight-Mode SAR Imagery

    Energy Technology Data Exchange (ETDEWEB)

    DOREN,NEALL E.

    1999-10-01

    Wavefront curvature defocus effects occur in spotlight-mode SAR imagery when reconstructed via the well-known polar-formatting algorithm (PFA) under certain imaging scenarios. These include imaging at close range, using a very low radar center frequency, utilizing high resolution, and/or imaging very large scenes. Wavefront curvature effects arise from the unrealistic assumption of strictly planar wavefronts illuminating the imaged scene. This dissertation presents a method for the correction of wavefront curvature defocus effects under these scenarios, concentrating on the generalized: squint-mode imaging scenario and its computational aspects. This correction is accomplished through an efficient one-dimensional, image domain filter applied as a post-processing step to PF.4. This post-filter, referred to as SVPF, is precalculated from a theoretical derivation of the wavefront curvature effect and varies as a function of scene location. Prior to SVPF, severe restrictions were placed on the imaged scene size in order to avoid defocus effects under these scenarios when using PFA. The SVPF algorithm eliminates the need for scene size restrictions when wavefront curvature effects are present, correcting for wavefront curvature in broadside as well as squinted collection modes while imposing little additional computational penalty for squinted images. This dissertation covers the theoretical development, implementation and analysis of the generalized, squint-mode SVPF algorithm (of which broadside-mode is a special case) and provides examples of its capabilities and limitations as well as offering guidelines for maximizing its computational efficiency. Tradeoffs between the PFA/SVPF combination and other spotlight-mode SAR image formation techniques are discussed with regard to computational burden, image quality, and imaging geometry constraints. It is demonstrated that other methods fail to exhibit a clear computational advantage over polar-formatting in conjunction

  6. OCT despeckling via weighted nuclear norm constrained non-local low-rank representation

    Science.gov (United States)

    Tang, Chang; Zheng, Xiao; Cao, Lijuan

    2017-10-01

    As a non-invasive imaging modality, optical coherence tomography (OCT) plays an important role in medical sciences. However, OCT images are always corrupted by speckle noise, which can mask image features and pose significant challenges for medical analysis. In this work, we propose an OCT despeckling method by using non-local, low-rank representation with weighted nuclear norm constraint. Unlike previous non-local low-rank representation based OCT despeckling methods, we first generate a guidance image to improve the non-local group patches selection quality, then a low-rank optimization model with a weighted nuclear norm constraint is formulated to process the selected group patches. The corrupted probability of each pixel is also integrated into the model as a weight to regularize the representation error term. Note that each single patch might belong to several groups, hence different estimates of each patch are aggregated to obtain its final despeckled result. Both qualitative and quantitative experimental results on real OCT images show the superior performance of the proposed method compared with other state-of-the-art speckle removal techniques.

  7. Using two coefficients modeling of nonsubsampled Shearlet transform for despeckling

    Science.gov (United States)

    Jafari, Saeed; Ghofrani, Sedigheh

    2016-01-01

    Synthetic aperture radar (SAR) images are inherently affected by multiplicative speckle noise. Two approaches based on modeling the nonsubsampled Shearlet transform (NSST) coefficients are presented. Two-sided generalized Gamma distribution and normal inverse Gaussian probability density function have been used to model the statistics of NSST coefficients. Bayesian maximum a posteriori estimator is applied to the corrupted NSST coefficients in order to estimate the noise-free NSST coefficients. Finally, experimental results, according to objective and subjective criteria, carried out on both artificially speckled images and the true SAR images, demonstrate that the proposed methods outperform other state of art references via two points of view, speckle noise reduction and image quality preservation.

  8. An improved adaptive wavelet shrinkage for ultrasound despeckling

    Indian Academy of Sciences (India)

    A comparison of the results shows that the proposed filter achieves an improvement in terms of quantitative measures and in terms of visual quality of the images. ... Kongu Engineering College, Perundurai 638 052, India; Department of Electronics and Communication Engineering, Kongunadu College of Engineering and ...

  9. TerraSAR-X StripMap Data Interpretation of Complex Urban Scenarios with 3D SAR Tomography

    Directory of Open Access Journals (Sweden)

    Lianhuan Wei

    2014-01-01

    Full Text Available The severe layover problem of complex urban scenarios in SAR data makes SAR data interpretation very difficult, especially for nonexperts. In this paper, we use 3D SAR tomography for SAR data interpretation of dense urban areas. An efficient and robust approach named Butterworth-filter based singular value decomposition (BSVD is used for tomographic analysis. Two typical dense urban areas of interest located in Shanghai are analyzed. The tomographic results could help users to better understand the backscattering scenario. The experimental results indicate that SAR tomography is a promising and effective way to facilitate SAR data interpretation of complex urban areas.

  10. Recovering Seasat SAR Data

    Science.gov (United States)

    Logan, T. A.; Arko, S. A.; Rosen, P. A.

    2013-12-01

    To demonstrate the feasibility of orbital remote sensing for global ocean observations, NASA launched Seasat on June 27th, 1978. Being the first space borne SAR mission, Seasat produced the most detailed SAR images of Earth from space ever seen to that point in time. While much of the data collected in the USA was processed optically, a mere 150 scenes had been digitally processed by March 1980. In fact, only an estimated 3% of Seasat data was ever digitally processed. Thus, for over three decades, the majority of the SAR data from this historic mission has been dormant, virtually unavailable to scientists in the 21st century. Over the last year, researchers at the Alaska Satellite Facility (ASF) Distributed Active Archive Center (DAAC) have processed the Seasat SAR archives into imagery products. A telemetry decoding system was created and the data were filtered into readily processable signal files. Due to nearly 35 years of bit rot, the bit error rate (BER) for the ASF DAAC Seasat archives was on the order of 1 out of 100 to 1 out of 100,000. This extremely high BER initially seemed to make much of the data undecodable - because the minor frame numbers are just 7 bits and no range line numbers exist in the telemetry even the 'simple' tasks of tracking the minor frame number or locating the start of each range line proved difficult. Eventually, using 5 frame numbers in sequence and a handful of heuristics, the data were successfully decoded into full range lines. Concurrently, all metadata were stored into external files. Recovery of this metadata was also problematic, the BER making the information highly suspect and, initially at least, unusable in any sort of automated fashion. Because of the BER, all of the single bit metadata fields proved unreliable. Even fields that should be constant for a data take (e.g. receiving station, day of the year) showed high variability, each requiring a median filter to be usable. The most challenging, however, were the

  11. Spiking cortical model based non-local means method for despeckling multiframe optical coherence tomography data

    Science.gov (United States)

    Gu, Yameng; Zhang, Xuming

    2017-05-01

    Optical coherence tomography (OCT) images are severely degraded by speckle noise. Existing methods for despeckling multiframe OCT data cannot deliver sufficient speckle suppression while preserving image details well. To address this problem, the spiking cortical model (SCM) based non-local means (NLM) method has been proposed in this letter. In the proposed method, the considered frame and two neighboring frames are input into three SCMs to generate the temporal series of pulse outputs. The normalized moment of inertia (NMI) of the considered patches in the pulse outputs is extracted to represent the rotational and scaling invariant features of the corresponding patches in each frame. The pixel similarity is computed based on the Euclidean distance between the NMI features and used as the weight. Each pixel in the considered frame is restored by the weighted averaging of all pixels in the pre-defined search window in the three frames. Experiments on the real multiframe OCT data of the pig eye demonstrate the advantage of the proposed method over the frame averaging method, the multiscale sparsity based tomographic denoising method, the wavelet-based method and the traditional NLM method in terms of visual inspection and objective metrics such as signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), equivalent number of looks (ENL) and cross-correlation (XCOR).

  12. Circular SAR GMTI

    Science.gov (United States)

    Page, Douglas; Owirka, Gregory; Nichols, Howard; Scarborough, Steven

    2014-06-01

    We describe techniques for improving ground moving target indication (GMTI) performance in multi-channel synthetic aperture radar (SAR) systems. Our approach employs a combination of moving reference processing (MRP) to compensate for defocus of moving target SAR responses and space-time adaptive processing (STAP) to mitigate the effects of strong clutter interference. Using simulated moving target and clutter returns, we demonstrate focusing of the target return using MRP, and discuss the effect of MRP on the clutter response. We also describe formation of adaptive degrees of freedom (DOFs) for STAP filtering of MRP processed data. For the simulated moving target in clutter example, we demonstrate improvement in the signal to interference plus noise (SINR) loss compared to more standard algorithm configurations. In addition to MRP and STAP, the use of tracker feedback, false alarm mitigation, and parameter estimation techniques are also described. A change detection approach for reducing false alarms from clutter discretes is outlined, and processing of a measured data coherent processing interval (CPI) from a continuously orbiting platform is described. The results demonstrate detection and geolocation of a high-value target under track. The endoclutter target is not clearly visible in single-channel SAR chips centered on the GMTI track prediction. Detections are compared to truth data before and after geolocation using measured angle of arrival (AOA).

  13. Severe Acute Respiratory Syndrome- SARS

    Indian Academy of Sciences (India)

    Table of contents. Severe Acute Respiratory Syndrome- SARS · PowerPoint Presentation · Slide 3 · Global pattern of SARS epidemic · Slide 5 · SARS – clinical features ... SARS virus · SARS – Koch´Postulates proved. SARS – virus jumps species · How infectious is SARS virus · SARS – Global Distribution- 10th July 2003.

  14. Wetland InSAR

    Science.gov (United States)

    Wdowinski, S.; Kim, S.; Amelung, F.; Dixon, T.

    2006-12-01

    Wetlands are transition zones where the flow of water, the nutrient cycling, and the sun energy meet to produce a unique and very productive ecosystem. They provide critical habitat for a wide variety of plant and animal species, including the larval stages of many ocean fish. Wetlands also have a valuable economical importance, as they filter nutrients and pollutants from fresh water used by human and provide aquatic habitats for outdoor recreation, tourism, and fishing. Globally, many such regions are under severe environmental stress, mainly from urban development, pollution, and rising sea level. However, there is increasing recognition of the importance of these habitats, and mitigation and restoration activities have begun in a few regions. A key element in wetlands conservation, management, and restoration involves monitoring its hydrologic system, as the entire ecosystem depends on its water supply. Heretofore, hydrologic monitoring of wetlands are conducted by stage (water level) stations, which provide good temporal resolution, but suffer from poor spatial resolution, as stage station are typically distributed several, or even tens of kilometers, from one another. Wetland application of InSAR provides the needed high spatial resolution hydrological observations, complementing the high temporal resolution terrestrial observations. Although conventional wisdom suggests that interferometry does not work in vegetated areas, several studies have shown that both L- and C-band interferograms with short acquisition intervals (1-105 days) can maintain excellent coherence over wetlands. In this study we explore the usage of InSAR for detecting water level changes in various wetland environments around the world, including the Everglades (south Florida), Louisiana Coast (southern US), Chesapeake Bay (eastern US), Pantanal (Brazil), Okavango Delta (Botswana), and Lena Delta (Siberia). Our main study area is the Everglades wetland (south Florida), which is covered by

  15. Digital demodulator for wide bandwidth SAR

    DEFF Research Database (Denmark)

    Jørgensen, Jørn Hjelm

    2000-01-01

    A novel approach to the design of efficient digital quadrature demodulators for wide bandwidth SAR systems is described. Efficiency is obtained by setting the intermediate frequency to 1/4 the ADC sampling frequency. One channel is made filter-free by synchronizing the local oscillator with the o......A novel approach to the design of efficient digital quadrature demodulators for wide bandwidth SAR systems is described. Efficiency is obtained by setting the intermediate frequency to 1/4 the ADC sampling frequency. One channel is made filter-free by synchronizing the local oscillator...

  16. Geodetic SAR Tomography

    NARCIS (Netherlands)

    Zhu, Xiao Xiang; Montazeri, Sina; Gisinger, Christoph; Hanssen, R.F.; Bamler, Richard

    2016-01-01

    In this paper, we propose a framework referred to as 'geodetic synthetic aperture radar (SAR) tomography' that fuses the SAR imaging geodesy and tomographic SAR inversion (TomoSAR) approaches to obtain absolute 3-D positions of a large amount of natural scatterers. The methodology is applied on

  17. CFAR Edge Detector for Polarimetric SAR Images

    DEFF Research Database (Denmark)

    Schou, Jesper; Skriver, Henning; Nielsen, Allan Aasbjerg

    2003-01-01

    Finding the edges between different regions in an image is one of the fundamental steps of image analysis, and several edge detectors suitable for the special statistics of synthetic aperture radar (SAR) intensity images have previously been developed. In this paper, a new edge detector for polar......Finding the edges between different regions in an image is one of the fundamental steps of image analysis, and several edge detectors suitable for the special statistics of synthetic aperture radar (SAR) intensity images have previously been developed. In this paper, a new edge detector...... for polarimetric SAR images is presented using a newly developed test statistic in the complex Wishart distribution to test for equality of covariance matrices. The new edge detector can be applied to a wide range of SAR data from single-channel intensity data to multifrequency and/or multitemporal polarimetric...... SAR data. By simply changing the parameters characterizing the test statistic according to the applied SAR data, constant false-alarm rate detection is always obtained. An adaptive filtering scheme is presented, and the distributions of the detector are verified using simulated polarimetric SAR images...

  18. Crop identification of SAR data using digital textural analysis

    Science.gov (United States)

    Nuesch, D. R.

    1983-01-01

    After preprocessing SEASAT SAR data which included slant to ground range transformation, registration to LANDSAT MSS data and appropriate filtering of the raw SAR data to minimize coherent speckle, textural features were developed based upon the spatial gray level dependence method (SGLDM) to compute entropy and inertia as textural measures. It is indicated that the consideration of texture features are very important in SAR data analysis. The SEASAT SAR data are useful for the improvement of field boundary definitions and for an earlier season estimate of corn and soybean area location than is supported by LANDSAT alone.

  19. SAR-PC: Edge Detection in SAR Images via an Advanced Phase Congruency Model

    Directory of Open Access Journals (Sweden)

    Yuming Xiang

    2017-02-01

    Full Text Available Edge detection in Synthetic Aperture Radar (SAR images has been a challenging task due to the speckle noise. Ratio-based edge detectors are robust operators for SAR images that provide constant false alarm rates, but they are only optimal for step edges. Edge detectors developed by the phase congruency model provide the identification of different types of edge features, but they suffer from speckle noise. By combining the advantages of the two edge detectors, we propose a SAR phase congruency detector (SAR-PC. Firstly, an improved local energy model for SAR images is obtained by replacing the convolution of raw image and the quadrature filters by the ratio responses. Secondly, a new noise level is estimated for the multiplicative noise. Substituting the SAR local energy and the new noise level into the phase congruency model, SAR-PC is derived. Edge response corresponds to the max moment of SAR-PC. We compare the proposed detector with the ratio-based edge detectors and the phase congruency edge detectors. Receiver Operating Characteristic (ROC curves and visual effects are used to evaluate the performance. Experimental results of simulated images and real-world images show that the proposed edge detector is robust to speckle noise and it provides a consecutive edge response.

  20. Estimating IMU heading error from SAR images.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2009-03-01

    Angular orientation errors of the real antenna for Synthetic Aperture Radar (SAR) will manifest as undesired illumination gradients in SAR images. These gradients can be measured, and the pointing error can be calculated. This can be done for single images, but done more robustly using multi-image methods. Several methods are provided in this report. The pointing error can then be fed back to the navigation Kalman filter to correct for problematic heading (yaw) error drift. This can mitigate the need for uncomfortable and undesired IMU alignment maneuvers such as S-turns.

  1. Severe acute respiratory syndrome (SARS)

    Science.gov (United States)

    SARS; Respiratory failure - SARS ... Complications may include: Respiratory failure Liver failure Heart failure ... 366. McIntosh K, Perlman S. Coronaviruses, including severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). ...

  2. Digital filter design for radar image formation

    Science.gov (United States)

    Adams, John W.; Nelson, Jeffrey E.; Banh, N. D.; Moncada, John J.; Bayma, Robert W.

    1989-01-01

    Novel weighted-least-squares approaches to the design of digital filters for SAR applications are presented. The filters belong to three different categories according to their combinations of minimax passband, least-squares stopband, minimax stopband, and maximally-flat passband. For real-time applications, it is important to design the sets of digital filter coefficient tables in an offline environment; the appropriate precomputed filter is then selected for each SAR signal-processing function, as a function of both mode and mapping geometry during real-time processing.

  3. SARS Pathogenesis: Host Factors

    NARCIS (Netherlands)

    A. de Lang (Anna)

    2012-01-01

    textabstractWhile it is hypothesized that Sever Acute Respiratory Syndrome (SARS) in humans is caused by a disproportional immune response illustrated by inappropriate induction of inflammatory cytokines, the exact nature of the host response to SARS coronavirus (CoV) infection causing severe

  4. Restoration of polarimetric SAR images using simulated annealing

    DEFF Research Database (Denmark)

    Schou, Jesper; Skriver, Henning

    2001-01-01

    Filtering synthetic aperture radar (SAR) images ideally results in better estimates of the parameters characterizing the distributed targets in the images while preserving the structures of the nondistributed targets. However, these objectives are normally conflicting, often leading to a filtering...... approach favoring one of the objectives. An algorithm for estimating the radar cross-section (RCS) for intensity SAR images has previously been proposed in the literature based on Markov random fields and the stochastic optimization method simulated annealing. A new version of the algorithm is presented...... applicable to multilook polarimetric SAR images, resulting in an estimate of the mean covariance matrix rather than the RCS. Small windows are applied in the filtering, and due to the iterative nature of the approach, reasonable estimates of the polarimetric quantities characterizing the distributed targets...

  5. SAR: Stroke Authorship Recognition

    KAUST Repository

    Shaheen, Sara

    2015-10-15

    Are simple strokes unique to the artist or designer who renders them? If so, can this idea be used to identify authorship or to classify artistic drawings? Also, could training methods be devised to develop particular styles? To answer these questions, we propose the Stroke Authorship Recognition (SAR) approach, a novel method that distinguishes the authorship of 2D digitized drawings. SAR converts a drawing into a histogram of stroke attributes that is discriminative of authorship. We provide extensive classification experiments on a large variety of data sets, which validate SAR\\'s ability to distinguish unique authorship of artists and designers. We also demonstrate the usefulness of SAR in several applications including the detection of fraudulent sketches, the training and monitoring of artists in learning a particular new style and the first quantitative way to measure the quality of automatic sketch synthesis tools. © 2015 The Eurographics Association and John Wiley & Sons Ltd.

  6. Apodized RFI filtering of synthetic aperture radar images

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2014-02-01

    Fine resolution Synthetic Aperture Radar (SAR) systems necessarily require wide bandwidths that often overlap spectrum utilized by other wireless services. These other emitters pose a source of Radio Frequency Interference (RFI) to the SAR echo signals that degrades SAR image quality. Filtering, or excising, the offending spectral contaminants will mitigate the interference, but at a cost of often degrading the SAR image in other ways, notably by raising offensive sidelobe levels. This report proposes borrowing an idea from nonlinear sidelobe apodization techniques to suppress interference without the attendant increase in sidelobe levels. The simple post-processing technique is termed Apodized RFI Filtering (ARF).

  7. SARS Requests for Information

    National Research Council Canada - National Science Library

    Rob Hare

    2016-01-01

      It is an increasingly common scenario: the South African Revenue Service (SARS) sends a taxpayer a request for information and, if it does not receive a response, proceeds to issue tax assessments against that taxpayer...

  8. Automatic detection and mapping of oil spill using SAR images

    Energy Technology Data Exchange (ETDEWEB)

    Assilzadeh, H.; Gao, Y. [Calgary Univ., AB (Canada). Schulich School of Engineering, Dept. of Geomatics Engineering

    2008-07-01

    Satellite remote sensing can act as a supplement for other aerial observations for offshore oil spills that cover vast areas of the marine environment. A method for automatic detection and mapping of oil spills in synthetic aperture radar (SAR) images was presented. The proposed SAR framework includes detecting and classifying spilled areas based on texture analysis, thresholding, Gamma filtering and unsupervised classification. SAR is suitable for spills in situations when the oil cannot be seen or discriminated against the background. The automatic processing of a radar image for oil spill detection and delineation in seawater and coastal areas was demonstrated in this paper. Radar signatures were shown to be effective in distinguishing different regions of an oil spill, and classifying the oil spill region into 3 classes according to spill thicknesses. Classification is based on a gradient of back scattering value in spilled regions through different oil concentrations. However, there are some limitations regarding weather conditions in identifying oil slicks. At high winds, the oil may be washed down into the sea, leaving no surface effect in the SAR image. In addition, since SAR signals cannot be received at very low winds, no slicks can be observed. Experienced operators are needed to distinguish false alarms that may occur when processing oil spill look-alikes such as natural surfactants, sea alga and grease ice. The proposed SAR framework was shown to provide valuable information about oil spill scenarios and the extent of polluted areas. 26 refs., 4 figs.

  9. Crop Classification by Polarimetric SAR

    DEFF Research Database (Denmark)

    Skriver, Henning; Svendsen, Morten Thougaard; Nielsen, Flemming

    1999-01-01

    Polarimetric SAR-data of agricultural fields have been acquired by the Danish polarimetric L- and C-band SAR (EMISAR) during a number of missions at the Danish agricultural test site Foulum during 1995. The data are used to study the classification potential of polarimetric SAR data using...... the Wishart distributed covariance matrix. In general, the improvement of using polarimetric SAR data compared to multipolarization SAR data is larger at L-band compared to C-band. On the other hand, the variability due to natural variation and different incidence angles is larger at L-band compared to C-band...

  10. Bats and SARS

    Centers for Disease Control (CDC) Podcasts

    2006-11-08

    Bats are a natural reservoir for emerging viruses, among them henipaviruses and rabies virus variants. Dr. Nina Marano, Chief, Geographic Medicine and Health Promotion Branch, Division of Global Migration and Quarantine, CDC, explains connection between horseshoe bats and SARS coronavirus transmission.  Created: 11/8/2006 by Emerging Infectious Diseases.   Date Released: 11/17/2006.

  11. Data Analytics for SAR

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, David Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Calef, Matthew Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-02

    We assess the ability of variants of anomalous change detection (ACD) to identify human activity associated with large outdoor music festivals as they are seen from synthetic aperture radar (SAR) imagery collected by the Sentinel-1 satellite constellation. We found that, with appropriate feature vectors, ACD using random-forest machine learning was most effective at identifying changes associated with the human activity.

  12. Bistatic SAR: Proof of Concept.

    Energy Technology Data Exchange (ETDEWEB)

    Yocky, David A.; Doren, Neall E.; Bacon, Terry A.; Wahl, Daniel E.; Eichel, Paul H.; Jakowatz, Charles V,; Delaplain, Gilbert G.; Dubbert, Dale F.; Tise, Bertice L.; White, Kyle R.

    2014-10-01

    Typical synthetic aperture RADAR (SAR) imaging employs a co-located RADAR transmitter and receiver. Bistatic SAR imaging separates the transmitter and receiver locations. A bistatic SAR configuration allows for the transmitter and receiver(s) to be in a variety of geometric alignments. Sandia National Laboratories (SNL) / New Mexico proposed the deployment of a ground-based RADAR receiver. This RADAR receiver was coupled with the capability of digitizing and recording the signal collected. SNL proposed the possibility of creating an image of targets the illuminating SAR observes. This document describes the developed hardware, software, bistatic SAR configuration, and its deployment to test the concept of a ground-based bistatic SAR. In the proof-of-concept experiments herein, the RADAR transmitter will be a commercial SAR satellite and the RADAR receiver will be deployed at ground level, observing and capturing RADAR ground/targets illuminated by the satellite system.

  13. Robust Ground Target Detection by SAR and IR Sensor Fusion Using Adaboost-Based Feature Selection

    Directory of Open Access Journals (Sweden)

    Sungho Kim

    2016-07-01

    Full Text Available Long-range ground targets are difficult to detect in a noisy cluttered environment using either synthetic aperture radar (SAR images or infrared (IR images. SAR-based detectors can provide a high detection rate with a high false alarm rate to background scatter noise. IR-based approaches can detect hot targets but are affected strongly by the weather conditions. This paper proposes a novel target detection method by decision-level SAR and IR fusion using an Adaboost-based machine learning scheme to achieve a high detection rate and low false alarm rate. The proposed method consists of individual detection, registration, and fusion architecture. This paper presents a single framework of a SAR and IR target detection method using modified Boolean map visual theory (modBMVT and feature-selection based fusion. Previous methods applied different algorithms to detect SAR and IR targets because of the different physical image characteristics. One method that is optimized for IR target detection produces unsuccessful results in SAR target detection. This study examined the image characteristics and proposed a unified SAR and IR target detection method by inserting a median local average filter (MLAF, pre-filter and an asymmetric morphological closing filter (AMCF, post-filter into the BMVT. The original BMVT was optimized to detect small infrared targets. The proposed modBMVT can remove the thermal and scatter noise by the MLAF and detect extended targets by attaching the AMCF after the BMVT. Heterogeneous SAR and IR images were registered automatically using the proposed RANdom SAmple Region Consensus (RANSARC-based homography optimization after a brute-force correspondence search using the detected target centers and regions. The final targets were detected by feature-selection based sensor fusion using Adaboost. The proposed method showed good SAR and IR target detection performance through feature selection-based decision fusion on a synthetic

  14. Two dimensional estimates from ocean SAR images

    Directory of Open Access Journals (Sweden)

    J. M. Le Caillec

    1996-01-01

    Full Text Available Synthetic Aperture Radar (SAR images of the ocean yield a lot of information on the sea-state surface providing that the mapping process between the surface and the image is clearly defined. However it is well known that SAR images exhibit non-gaussian statistics and that the motion of the scatterers on the surface, while the image is being formed, may yield to nonlinearities. The detection and quantification of these nonlinearities are made possible by using Higher Order Spectra (HOS methods and more specifically, bispectrum estimation. The development of the latter method allowed us to find phase relations between different parts of the image and to recognise their level of coupling, i.e. if and how waves of different wavelengths interacted nonlinearly. This information is quite important as the usual models assume strong nonlinearities when the waves are propagating in the azimuthal direction (i.e. along the satellite track and almost no nonlinearities when propagating in the range direction. In this paper, the mapping of the ocean surface to the SAR image is reinterpreted and a specific model (i.e. a Second Order Volterra Model is introduced. The nonlinearities are thus explained as either produced by a nonlinear system or due to waves propagating into selected directions (azimuth or range and interacting during image formation. It is shown that quadratic nonlinearities occur for waves propagating near the range direction while for those travelling in the azimuthal direction the nonlinearities, when present, are mostly due to wave interactions but are almost completely removed by the filtering effect coming from the surface motion itself (azimuth cut-off. An inherent quadratic interaction filtering (azimuth high pass filter is also present. But some other effects, apparently nonlinear, are not detected with the methods described here, meaning that either the usual relation developed for the Ocean-to-SAR transform is somewhat incomplete

  15. Bistatic sAR data processing algorithms

    CERN Document Server

    Qiu, Xiaolan; Hu, Donghui

    2013-01-01

    Synthetic Aperture Radar (SAR) is critical for remote sensing. It works day and night, in good weather or bad. Bistatic SAR is a new kind of SAR system, where the transmitter and receiver are placed on two separate platforms. Bistatic SAR is one of the most important trends in SAR development, as the technology renders SAR more flexible and safer when used in military environments. Imaging is one of the most difficult and important aspects of bistatic SAR data processing. Although traditional SAR signal processing is fully developed, bistatic SAR has a more complex system structure, so sign

  16. SAR Imagery Segmentation by Statistical Region Growing and Hierarchical Merging

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela Mayumi; Carvalho, E.A.; Medeiros, F.N.S.; Martins, C.I.O.; Marques, R.C.P.; Oliveira, I.N.S.

    2010-05-22

    This paper presents an approach to accomplish synthetic aperture radar (SAR) image segmentation, which are corrupted by speckle noise. Some ordinary segmentation techniques may require speckle filtering previously. Our approach performs radar image segmentation using the original noisy pixels as input data, eliminating preprocessing steps, an advantage over most of the current methods. The algorithm comprises a statistical region growing procedure combined with hierarchical region merging to extract regions of interest from SAR images. The region growing step over-segments the input image to enable region aggregation by employing a combination of the Kolmogorov-Smirnov (KS) test with a hierarchical stepwise optimization (HSWO) algorithm for the process coordination. We have tested and assessed the proposed technique on artificially speckled image and real SAR data containing different types of targets.

  17. SAR++: A Multi-Channel Scalable and Reconfigurable SAR System

    DEFF Research Database (Denmark)

    Høeg, Flemming; Christensen, Erik Lintz

    2002-01-01

    SAR++ is a technology program aiming at developing know-how and technology needed to design the next generation civilian SAR systems. Technology has reached a state, which allows major parts of the digital subsystem to be built using custom-off-the-shelf (COTS) components. A design goal...... is to design a modular, scalable and reconfigurable SAR system using such components, in order to ensure maximum flexibility for the users of the actual system and for future system updates. Having these aspects in mind the SAR++ system is presented with focus on the digital subsystem architecture...

  18. Methods of InSAR atmosphere correction for volcano activity monitoring

    Science.gov (United States)

    Gong, W.; Meyer, F.; Webley, P.W.; Lu, Z.

    2011-01-01

    When a Synthetic Aperture Radar (SAR) signal propagates through the atmosphere on its path to and from the sensor, it is inevitably affected by atmospheric effects. In particular, the applicability and accuracy of Interferometric SAR (InSAR) techniques for volcano monitoring is limited by atmospheric path delays. Therefore, atmospheric correction of interferograms is required to improve the performance of InSAR for detecting volcanic activity, especially in order to advance its ability to detect subtle pre-eruptive changes in deformation dynamics. In this paper, we focus on InSAR tropospheric mitigation methods and their performance in volcano deformation monitoring. Our study areas include Okmok volcano and Unimak Island located in the eastern Aleutians, AK. We explore two methods to mitigate atmospheric artifacts, namely the numerical weather model simulation and the atmospheric filtering using Persistent Scatterer processing. We investigate the capability of the proposed methods, and investigate their limitations and advantages when applied to determine volcanic processes. ?? 2011 IEEE.

  19. Novel Polarimetric SAR Interferometry Algorithms Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Polarimetric SAR interferometry (PolInSAR) is a recently developed synthetic aperture radar (SAR) imaging mode that combines the capabilities of radar polarimetry...

  20. Detection and Imaging of Moving Targets with LiMIT SAR Data

    Science.gov (United States)

    2017-03-03

    sandeep.mishra@baesystems.com Abstract Detecting moving targets in SAR imagery has recently gained a lot of interest as a way to replace optical...movers by applying a set of possible motion corrections to the image, and use a novel matched filter to detect the movers in this space. We can then image...called SAR-GMTI) has recently gained a lot of interest as a way to image and classify moving targets, and to mitigate GMTI performance gaps. Synthetic

  1. G0-WISHART Distribution Based Classification from Polarimetric SAR Images

    Science.gov (United States)

    Hu, G. C.; Zhao, Q. H.

    2017-09-01

    Enormous scientific and technical developments have been carried out to further improve the remote sensing for decades, particularly Polarimetric Synthetic Aperture Radar(PolSAR) technique, so classification method based on PolSAR images has getted much more attention from scholars and related department around the world. The multilook polarmetric G0-Wishart model is a more flexible model which describe homogeneous, heterogeneous and extremely heterogeneous regions in the image. Moreover, the polarmetric G0-Wishart distribution dose not include the modified Bessel function of the second kind. It is a kind of simple statistical distribution model with less parameter. To prove its feasibility, a process of classification has been tested with the full-polarized Synthetic Aperture Radar (SAR) image by the method. First, apply multilook polarimetric SAR data process and speckle filter to reduce speckle influence for classification result. Initially classify the image into sixteen classes by H/A/α decomposition. Using the ICM algorithm to classify feature based on the G0-Wshart distance. Qualitative and quantitative results show that the proposed method can classify polaimetric SAR data effectively and efficiently.

  2. Interactive Web Based Visualization of PS-InSAR and TomoSAR Results

    Science.gov (United States)

    Li, Shanshan; Wei, Lianhuan; Balz, Timo; Liao, Mingsheng

    2013-01-01

    Interactive web based visualization has become an important trend for displaying information dynamically. Synthetic Aperture Radar (SAR) data can be used to measure height and deformation information using interferometric SAR (InSAR) and differential InSAR (D-InSAR). Precise deformation information can be acquired in urban areas using Persistent Scatterer Interferometry (PS-InSAR) and differential SAR tomography (D-TomoSAR). PS-InSAR and TomoSAR results are usually represented as point clouds. In order to visualize this data dynamically, we developed an interactive web-based visualization system.

  3. Interactive Web-Based Visualization of PS-InSAR and TomoSAR

    Science.gov (United States)

    Li, Shanshan; Wei, Lianhuan; Balz, Timo; Liao, Mingsheng

    2013-01-01

    Interactive web based visualization has become an important trend for displaying information dynamically. Synthetic Aperture Radar (SAR) data can be used to measure height and deformation information using interferometric SAR (InSAR) and differential InSAR (D-InSAR). Precise deformation information can be acquired in urban areas using Persistent Scatterer Interferometry (PS-InSAR) and differential SAR tomography (D-TomoSAR). PS-InSAR and TomoSAR results are usually represented as point clouds. In order to visualize this data dynamically, we developed an interactive web-based visualization system

  4. Effect of wind turbine micro-Doppler on SAR and GMTI signatures

    Science.gov (United States)

    Bhalla, Rajan; Ling, Hao

    2014-05-01

    In this paper, we present the results of a modeling study to examine the interference effect of microDopplers caused by offshore wind farms on airborne sensors operating in the synthetic aperture radar (SAR) and ground moving target indicator (GMTI) modes. The modeling is carried out by generating CAD instantiations of the dynamic wind turbine and using the high-frequency electromagnetic code Xpatch to perform the scattering calculations. Artifacts in the resulting SAR and GMTI signatures are evaluated for interference with tracking of boats in coastal waters. Results of signal filtering algorithms to reduce the dynamic turbine clutter in both SAR images and GMTI displays are presented.

  5. Pixel Classification of SAR ice images using ANFIS-PSO Classifier

    Directory of Open Access Journals (Sweden)

    G. Vasumathi

    2016-12-01

    Full Text Available Synthetic Aperture Radar (SAR is playing a vital role in taking extremely high resolution radar images. It is greatly used to monitor the ice covered ocean regions. Sea monitoring is important for various purposes which includes global climate systems and ship navigation. Classification on the ice infested area gives important features which will be further useful for various monitoring process around the ice regions. Main objective of this paper is to classify the SAR ice image that helps in identifying the regions around the ice infested areas. In this paper three stages are considered in classification of SAR ice images. It starts with preprocessing in which the speckled SAR ice images are denoised using various speckle removal filters; comparison is made on all these filters to find the best filter in speckle removal. Second stage includes segmentation in which different regions are segmented using K-means and watershed segmentation algorithms; comparison is made between these two algorithms to find the best in segmenting SAR ice images. The last stage includes pixel based classification which identifies and classifies the segmented regions using various supervised learning classifiers. The algorithms includes Back propagation neural networks (BPN, Fuzzy Classifier, Adaptive Neuro Fuzzy Inference Classifier (ANFIS classifier and proposed ANFIS with Particle Swarm Optimization (PSO classifier; comparison is made on all these classifiers to propose which classifier is best suitable for classifying the SAR ice image. Various evaluation metrics are performed separately at all these three stages.

  6. SAR Simulations & Safety.

    Science.gov (United States)

    Fiedler, Thomas M; Ladd, Mark E; Bitz, Andreas K

    2017-03-20

    At ultra-high fields, the assessment of radiofrequency (RF) safety presents several new challenges compared to low-field systems. Multi-channel RF transmit coils in combination with parallel transmit techniques produce time-dependent and spatially varying power loss densities in the tissue. Further, in ultra-high-field systems, localized field effects can be more pronounced due to a transition from the quasi stationary to the electromagnetic field regime. Consequently, local information on the RF field is required for reliable RF safety assessment as well as for monitoring of RF exposure during MR examinations. Numerical RF and thermal simulations for realistic exposure scenarios with anatomical body models are currently the only practical way to obtain the requisite local information on magnetic and electric field distributions as well as tissue temperature. In this article, safety regulations and the fundamental characteristics of RF field distributions in ultra-high-field systems are reviewed. Numerical methods for computation of RF fields as well as typical requirements for the analysis of realistic multi-channel RF exposure scenarios including anatomical body models are highlighted. In recent years, computation of the local tissue temperature has become of increasing interest, since a more accurate safety assessment is expected because temperature is directly related to tissue damage. Regarding thermal simulation, bio-heat transfer models and approaches for taking into account the physiological response of the human body to RF exposure are discussed. In addition, suitable methods are presented to validate calculated RF and thermal results with measurements. Finally, the concept of generalized simulation-based specific absorption rate (SAR) matrix models is discussed. These models can be incorporated into local SAR monitoring in multi-channel MR systems and allow the design of RF pulses under constraints for local SAR. Copyright © 2017 Elsevier Inc. All rights

  7. Signal subspace change detection in averaged multi-look SAR imagery

    Science.gov (United States)

    Ranney, Kenneth; Soumekh, Mehrdad

    2005-05-01

    Modern Synthetic Aperture Radar (SAR) signal processing algorithms could retrieve accurate and subtle information regarding a scene that is being interrogated by an airborne radar system. An important reconnaissance problem that is being studied via the use of SAR systems and their sophisticated signal processing methods involves detecting changes in an imaged scene. In these problems, the user interrogates a scene with a SAR system at two different time points (e.g. different days); the resultant two SAR databases that we refer to as reference and test data, are used to determine where targets have entered or left the imaged scene between the two data acquisitions. For instance, X band SAR systems have the potential to become a potent tool to determine whether mines have been recently placed in an area. This paper describes an algorithm for detecting changes in averaged multi-look SAR imagery. Averaged multi-look SAR images are preferable to full aperture SAR reconstructions when the imaging algorithm is approximation based (e.g. polar format processing), or motion data are not accurate over a long full aperture. We study the application of a SAR detection method, known as Signal Subspace Processing, that is based on the principles of 2D adaptive filtering. We identify the change detection problem as a binary hypothesis-testing problem, and identify an error signal and its normalized version to determine whether i) there is no change in the imaged scene; or ii) a target has been added to the imaged scene. A statistical analysis of the error signal is provided to show its properties and merits. Results are provided for data collected by an X band SAR platform and processed to form non-coherently look-averaged SAR images.

  8. Bistatic SAR: Imagery & Image Products.

    Energy Technology Data Exchange (ETDEWEB)

    Yocky, David A.; Wahl, Daniel E.; Jakowatz, Charles V,

    2014-10-01

    While typical SAR imaging employs a co-located (monostatic) RADAR transmitter and receiver, bistatic SAR imaging separates the transmitter and receiver locations. The transmitter and receiver geometry determines if the scattered signal is back scatter, forward scatter, or side scatter. The monostatic SAR image is backscatter. Therefore, depending on the transmitter/receiver collection geometry, the captured imagery may be quite different that that sensed at the monostatic SAR. This document presents imagery and image products formed from captured signals during the validation stage of the bistatic SAR research. Image quality and image characteristics are discussed first. Then image products such as two-color multi-view (2CMV) and coherent change detection (CCD) are presented.

  9. Ambiguities analysis in SAR tomography

    Science.gov (United States)

    Wang, Ziwei; Zhang, Hong; Wang, Chao; Tang, Yixian; Zhang, Bo

    2014-10-01

    Synthetic aperture radar tomography (TomoSAR) is typically used to retrieve elevation, deformation, and other key information by separating scatters of the same slant range in multiple baseline SAR images. In this paper, we investigate two kinds of ambiguities for TomoSAR. Rank-1 ambiguity, as the first one we concerned, is due to the baseline distribution of the SAR image dataset which makes the steering matrix out of full rank. It will result in false alarms appearing in a permanent distance. However, an example using the TomoSAR imaging parameters shows this ambiguity makes no sense in most cases. The second ambiguity refers to the coherence of scatters contained in one pixel. In simulation experiment, the coherence will enhance the side lobes of the spectrum, even make the real peaks fused.

  10. Microwave Filters

    OpenAIRE

    Zhou, Jiafeng

    2010-01-01

    The general theory of microwave filter design based on lumped-element circuit is described in this chapter. The lowpass prototype filters with Butterworth, Chebyshev and quasielliptic characteristics are synthesized, and the prototype filters are then transformed to bandpass filters by lowpass to bandpass frequency mapping. By using immitance inverters ( J - or K -inverters), the bandpass filters can be realized by the same type of resonators. One design example is given to verify the theory ...

  11. a SAR Image Registration Method Based on Sift Algorithm

    Science.gov (United States)

    Lu, W.; Yue, X.; Zhao, Y.; Han, C.

    2017-09-01

    In order to improve the stability and rapidity of synthetic aperture radar (SAR) images matching, an effective method was presented. Firstly, the adaptive smoothing filtering was employed for image denoising in image processing based on Wallis filtering to avoid the follow-up noise is amplified. Secondly, feature points were extracted by a simplified SIFT algorithm. Finally, the exact matching of the images was achieved with these points. Compared with the existing methods, it not only maintains the richness of features, but a-lso reduces the noise of the image. The simulation results show that the proposed algorithm can achieve better matching effect.

  12. Noise and speckle reduction in synthetic aperture radar imagery by nonparametric Wiener filtering.

    Science.gov (United States)

    Caprari, R S; Goh, A S; Moffatt, E K

    2000-12-10

    We present a Wiener filter that is especially suitable for speckle and noise reduction in multilook synthetic aperture radar (SAR) imagery. The proposed filter is nonparametric, not being based on parametrized analytical models of signal statistics. Instead, the Wiener-Hopf equation is expressed entirely in terms of observed signal statistics, with no reference to the possibly unobservable pure signal and noise. This Wiener filter is simple in concept and implementation, exactly minimum mean-square error, and directly applicable to signal-dependent and multiplicative noise. We demonstrate the filtering of a genuine two-look SAR image and show how a nonnegatively constrained version of the filter substantially reduces ringing.

  13. Water Filters

    Science.gov (United States)

    1993-01-01

    The Aquaspace H2OME Guardian Water Filter, available through Western Water International, Inc., reduces lead in water supplies. The filter is mounted on the faucet and the filter cartridge is placed in the "dead space" between sink and wall. This filter is one of several new filtration devices using the Aquaspace compound filter media, which combines company developed and NASA technology. Aquaspace filters are used in industrial, commercial, residential, and recreational environments as well as by developing nations where water is highly contaminated.

  14. High Resolution Processing with an Active Phased Array SAR

    NARCIS (Netherlands)

    Nijenboer, F.J.; Otten, M.P.G.

    1999-01-01

    The Dutch PHARUS system is a polarimetric active phased array SAR capable of performing advanced SAR modes. Advanced SAR modes that are being investigated are: spotlight SAR, sliding spotlight SAR, stepped frequency SAR and interferometric SAR. The flight experiments and automatic beam steering

  15. Water Filters

    Science.gov (United States)

    1987-01-01

    A compact, lightweight electrolytic water filter generates silver ions in concentrations of 50 to 100 parts per billion in the water flow system. Silver ions serve as effective bactericide/deodorizers. Ray Ward requested and received from NASA a technical information package on the Shuttle filter, and used it as basis for his own initial development, a home use filter.

  16. SAR calculation using FDTD simulations

    OpenAIRE

    Ferro, Francisco Nabais; Pinto, Guilherme Taveira; Pinho, Pedro

    2009-01-01

    The main intend of this work, is to determinate the Specific Absorption Rate (SAR) on human head tissues exposed to radiation caused by sources of 900 and 1800MHz, since those are the typical frequencies for mobile communications systems nowadays. In order to determinate the SAR, has been used the FDTD (Finite Difference Time Domain), which is a numeric method in time domain, obtained from the Maxwell equations in differential mode. In order to do this, a computational model from the human he...

  17. Optimal filtering

    CERN Document Server

    Anderson, Brian D O

    1979-01-01

    This graduate-level text augments and extends beyond undergraduate studies of signal processing, particularly in regard to communication systems and digital filtering theory. Vital for students in the fields of control and communications, its contents are also relevant to students in such diverse areas as statistics, economics, bioengineering, and operations research.Topics include filtering, linear systems, and estimation; the discrete-time Kalman filter; time-invariant filters; properties of Kalman filters; computational aspects; and smoothing of discrete-time signals. Additional subjects e

  18. InSAR Scientific Computing Environment - The Home Stretch

    Science.gov (United States)

    Rosen, P. A.; Gurrola, E. M.; Sacco, G.; Zebker, H. A.

    2011-12-01

    . ISCE is now a complete, functional package, under configuration management, and with extensive documentation and tested use cases appropriate to geodetic imaging applications. The software has been tested with canonical simulated radar data ("point targets") as well as with a variety of existing satellite data, cross-compared with other software packages. Its extensibility has already been proven by the straightforward addition of polarimetric processing and calibration, and derived filtering and estimation routines associated with polarimetry that supplement the original InSAR geodetic functionality. As of October 2011, the software is available for non-commercial use through UNAVCO's WinSAR consortium.

  19. Exploitation of Digital Surface Models Generated from WORLDVIEW-2 Data for SAR Simulation Techniques

    Science.gov (United States)

    Ilehag, R.; Auer, S.; d'Angelo, P.

    2017-05-01

    GeoRaySAR, an automated SAR simulator developed at DLR, identifies buildings in high resolution SAR data by utilizing geometric knowledge extracted from digital surface models (DSMs). Hitherto, the simulator has utilized DSMs generated from LiDAR data from airborne sensors with pre-filtered vegetation. Discarding the need for pre-optimized model input, DSMs generated from high resolution optical data (acquired with WorldView-2) are used for the extraction of building-related SAR image parts in this work. An automatic preprocessing of the DSMs has been developed for separating buildings from elevated vegetation (trees, bushes) and reducing the noise level. Based on that, automated simulations are triggered considering the properties of real SAR images. Locations in three cities, Munich, London and Istanbul, were chosen as study areas to determine advantages and limitations related to WorldView-2 DSMs as input for GeoRaySAR. Beyond, the impact of the quality of the DSM in terms of building extraction is evaluated as well as evaluation of building DSM, a DSM only containing buildings. The results indicate that building extents can be detected with DSMs from optical satellite data with various success, dependent on the quality of the DSM as well as on the SAR imaging perspective.

  20. Characterizing forest stands with multi-incidence angle and multi-polarized SAR data

    Science.gov (United States)

    Hoffer, R. M.; Lozano-Garcia, D. F.; Gillespie, D. D.

    1987-01-01

    The potential for using HH-polarized L-band SAR data obtained at different incidence angles from satellite altitudes to identify and map different forest cover types and stand density classes is studied. Reasonably accurate results are obtained if the speckle characteristics of the data are suppressed by low-pass spatial filters and a contextual classification algorithm. Multipolarized L-band SAR data obtained from aircraft altitudes over the same test site are also analyzed to assess the relationships between polarization and forest stand characteristics. It is found that incidence angle controls, to a very large extent, the characteristics of the data and the type of information that can be obtained from L-band, HH-polarized satellite SAR data. Cross-polarization of L-band SAR data enhances and differentiates various forest stand characteristics which cannot be defined using only the like-polarized data, and vice-versa.

  1. Accelerated Scientific InSAR Processing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Neva Ridge Technologies proposes to develop a suite of software tools for the analysis of SAR and InSAR data, focused on having a robust and adopted capability well...

  2. Polarimetric and Interferometric SAR Calibration Verification Methods

    Science.gov (United States)

    Kim, Y.; Zyl, J van

    2001-01-01

    It is necessary to calibrate SAR data in order to use the data for science applications. When both polarimetric and interferometric data are collected simultaneously, these SAR data can be used for cross-calibration and verification.

  3. Novel Polarimetric SAR Interferometry Algorithms Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Polarimetric radar interferometry (PolInSAR) is a new SAR imaging mode that is rapidly becoming an important technique for bare earth topographic mapping, tree...

  4. SAR Tomography Based on Block Compressive Sensing

    National Research Council Canada - National Science Library

    Wang Aichun; Xiang Maosheng

    2016-01-01

    While the use of SAR Tomography (TomoSAR) based on Compressive Sensing (CS) makes it possible to reconstruct the height profile of an observed scene, the performance of the reconstruction decreases for a structural observed scene...

  5. SAR matrices: automated extraction of information-rich SAR tables from large compound data sets.

    Science.gov (United States)

    Wassermann, Anne Mai; Haebel, Peter; Weskamp, Nils; Bajorath, Jürgen

    2012-07-23

    We introduce the SAR matrix data structure that is designed to elucidate SAR patterns produced by groups of structurally related active compounds, which are extracted from large data sets. SAR matrices are systematically generated and sorted on the basis of SAR information content. Matrix generation is computationally efficient and enables processing of large compound sets. The matrix format is reminiscent of SAR tables, and SAR patterns revealed by different categories of matrices are easily interpretable. The structural organization underlying matrix formation is more flexible than standard R-group decomposition schemes. Hence, the resulting matrices capture SAR information in a comprehensive manner.

  6. SARS among Critical Care Nurses, Toronto

    OpenAIRE

    Loeb, Mark; McGeer, Allison; Henry, Bonnie; Ofner, Marianna; Rose, David; Hlywka, Tammy; Levie, Joanne; McQueen, Jane; Smith, Stephanie; Moss, Lorraine; Smith, Andrew; Green, Karen; Walter, Stephen D.

    2004-01-01

    To determine factors that predispose or protect healthcare workers from severe acute respiratory syndrome (SARS), we conducted a retrospective cohort study among 43 nurses who worked in two Toronto critical care units with SARS patients. Eight of 32 nurses who entered a SARS patient’s room were infected. The probability of SARS infection was 6% per shift worked. Assisting during intubation, suctioning before intubation, and manipulating the oxygen mask were high-risk activities. Consistently ...

  7. [SARS: diagnosis, therapy, and especially prevention].

    Science.gov (United States)

    Agolini, G; Raitano, A; Viotti, P L; Vitali, M; Zorzut, F

    2004-01-01

    The main purpose of this review is to analyze some aspects of the severe acute respiratory syndrome, SARS, in order to obtain useful data to suggest preventive actions to reduce the spreading of the disease. Many elements have been examined to reach some conclusions and to allow an updated discussion. Surgical masks protect more the patient than the caregiver. Simple or double surgical masks may be useful, as double gloving protects the hands of the surgical personnel against percutaneous transmission of HIV eventually present in contaminated blood. The frequent substitution of the external masks with a new one will improve the filtering activity against droplets produced by cough or sneezes of the patient. The use of respiratory masks may be suggested in hospitals or in restricted ventilated areas where, even if coronavirus variant is considered an environmental contaminant more than a respiratory risk, droplets nuclei may persist in the air and add consistent dangers to the heath-care givers. Considering that large and medium droplets may infect floors and surfaces, in addition to gloves, gowns, masks and eyes protection, the available list of viral and bacterial factors implicated in SARS ethiology suggests a better hand antisepsis using frequently the alcohol based gels (containing an high percentage of emollients substances), if available. A liquid soap with triclosan can also be used, if the health-care workers compliance to hand washing increases, as expected in this explosive situation. On the basis of the results of some experimental data, the environmental disinfection may be effected with ethyl alcohol 70% in water. Disinfection of floors or larger surfaces may be obtained with chlorine compounds solutions, after an accurate pre-cleaning. When corrosion, bleaching or gas production have to be avoided, chlorine compounds may be substituted by phenolic detergent disinfectants.

  8. The aetiology of SARS: Koch's postulates fulfilled

    NARCIS (Netherlands)

    A.D.M.E. Osterhaus (Albert); R.A.M. Fouchier (Ron); T. Kuiken (Thijs)

    2004-01-01

    textabstractProof that a newly identified coronavirus, severe acute respiratory syndrome coronavirus (SARS-CoV) is the primary cause of severe acute respiratory syndrome (SARS) came from a series of studies on experimentally infected cynomolgus macaques (Macaca, fascicularis). SARS-CoV-infected

  9. Convolutional Neural Networks for SAR Image Segmentation

    DEFF Research Database (Denmark)

    Malmgren-Hansen, David; Nobel-Jørgensen, Morten

    2015-01-01

    Segmentation of Synthetic Aperture Radar (SAR) images has several uses, but it is a difficult task due to a number of properties related to SAR images. In this article we show how Convolutional Neural Networks (CNNs) can easily be trained for SAR image segmentation with good results. Besides...

  10. SAR Systems and Related Signal Processing

    NARCIS (Netherlands)

    Hoogeboom, P.; Dekker, R.J.; Otten, M.P.G.

    1996-01-01

    Synthetic Aperture Radar (SAR) is today a valuable source of remote sensing information. SAR is a side-looking imaging radar and operates from airborne and spacebome platforms. Coverage, resolution and image quality are strongly influenced by the platform. SAR processing can be performed on standard

  11. Squint mode SAR processing algorithms

    Science.gov (United States)

    Chang, C. Y.; Jin, M.; Curlander, J. C.

    1989-01-01

    The unique characteristics of a spaceborne SAR (synthetic aperture radar) operating in a squint mode include large range walk and large variation in the Doppler centroid as a function of range. A pointing control technique to reduce the Doppler drift and a new processing algorithm to accommodate large range walk are presented. Simulations of the new algorithm for squint angles up to 20 deg and look angles up to 44 deg for the Earth Observing System (Eos) L-band SAR configuration demonstrate that it is capable of maintaining the resolution broadening within 20 percent and the ISLR within a fraction of a decibel of the theoretical value.

  12. Improved Goldstein Interferogram Filter Based on Local Fringe Frequency Estimation.

    Science.gov (United States)

    Feng, Qingqing; Xu, Huaping; Wu, Zhefeng; You, Yanan; Liu, Wei; Ge, Shiqi

    2016-11-23

    The quality of an interferogram, which is limited by various phase noise, will greatly affect the further processes of InSAR, such as phase unwrapping. Interferometric SAR (InSAR) geophysical measurements', such as height or displacement, phase filtering is therefore an essential step. In this work, an improved Goldstein interferogram filter is proposed to suppress the phase noise while preserving the fringe edges. First, the proposed adaptive filter step, performed before frequency estimation, is employed to improve the estimation accuracy. Subsequently, to preserve the fringe characteristics, the estimated fringe frequency in each fixed filtering patch is removed from the original noisy phase. Then, the residual phase is smoothed based on the modified Goldstein filter with its parameter alpha dependent on both the coherence map and the residual phase frequency. Finally, the filtered residual phase and the removed fringe frequency are combined to generate the filtered interferogram, with the loss of signal minimized while reducing the noise level. The effectiveness of the proposed method is verified by experimental results based on both simulated and real data.

  13. High resolution PolInSAR with the ground-based SAR (GB-SAR) System: measurement and modelling

    OpenAIRE

    Morrison, K; Williams, M L

    2006-01-01

    Ground-based work is necessary for a comprehensive assessment of the operational potential and limitations of PolInSAR in airborne and satellite SAR applications. A study is made of the performance and usefulness of the UK’s Ground-Based SAR (GB-SAR) Outdoor System in high-resolution PolInSAR studies of vegetation using modeling results. The facility provides fully-polarimetric L- through X-band imagery down to a resolution of several wavelengths. However, the measurem...

  14. SAR data for the analysis of forest features: current Brazilian experiences

    Directory of Open Access Journals (Sweden)

    Fábio Guimarães Gonçalves

    2006-12-01

    Full Text Available This article presents some applications of airborne polarimetric and/or interferometric microwave data to improve the knowledge of forest structures. Three airborne SAR (Synthetic Aperture Radar experiments were done in the Amazon tropical forest: (a to study the spatial distribution of very large trees (VLTs in the primary forest using local maximum filtering and a series of Markov processes; (b to model the estimation of biomass variations in primary and secondary forests; (c to analyze the retrieval of timber volume over selective logging areas. Another experiment (d was to investigate the relation among SAR data and the volumetric configuration in stands of Eucalyptus sp. done by an airborne SAR imaging mission in SE-Brazil. To perform the objectives (b, (c and (d we carry out regression techniques, using variables got from multipolarimetric and/or interferometric SAR attributes and biophysical parameters from the forest cover. All data from the experiments were calibrated radiometrically to extract information during digital processing, besides an exhaustive field survey which was done simultaneously to SAR imaging, to know the physiognomy/structure of forest typology and to support the models produced for each case. The results of this series of experiments show advances at the techniques to treat SAR data, focusing on models of stand architecture and forest stock density. This will be helpful to increase the regional inventory and surveying procedures of forest conversion in the Brazilian territory in the near future.

  15. Photographic filters

    Science.gov (United States)

    Rodigues, Jose Eduardo; Santosdealmeida, Wagner

    1987-12-01

    Some of the main aspects related to photographic filters are examined and prepared as a reference for researchers and students of remote sensing. A large range of information about the filters including their basic fundamentals, classification, and main types is presented. The theme cannot be exhausted in this or any other individual publication because of its great complexity, profound theoretical publication, and dynmaic technological development. The subject does not deal only with filter applications in remote sensing. As much as possible, additional information about the utilization of these products in other professional areas, as pictorial photography, photographic processing, and optical engineering, were included.

  16. Polarimetric scattering and SAR information retrieval

    CERN Document Server

    Jin, Ya-Qiu

    2013-01-01

    Taking an innovative look at Synthetic Aperture Radar (SAR), this practical reference fully covers new developments in SAR and its various methodologies and enables readers to interpret SAR imagery An essential reference on polarimetric Synthetic Aperture Radar (SAR), this book uses scattering theory and radiative transfer theory as a basis for its treatment of topics. It is organized to include theoretical scattering models and SAR data analysis techniques, and presents cutting-edge research on theoretical modelling of terrain surface. The book includes quantitative app

  17. Stalking SARS: CDC at Work

    Centers for Disease Control (CDC) Podcasts

    2014-05-22

    In this podcast for kids, the Kidtastics talk about the SARS outbreak and how CDC worked to solve the mystery.  Created: 5/22/2014 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 5/22/2014.

  18. Signal processing for FMCW SAR

    NARCIS (Netherlands)

    Meta, A.; Hoogeboom, P.; Ligthart, L.P.

    2007-01-01

    The combination of frequency-modulated continuous-wave (FMCW) technology and synthetic aperture radar (SAR) techniques leads to lightweight cost-effective imaging sensors of high resolution. One limiting factor to the use of FMCW sensors is the well-known presence of nonlinearities in the

  19. SARS – virus jumps species

    Indian Academy of Sciences (India)

    SARS – virus jumps species. Coronavirus reshuffles genes; Rotteir et al, Rotterdam showed the virus to jump from cats to mouse cells after single gene mutation ? Human disease due to virus jumping from wild or domestic animals; Present favourite animal - the cat; - edible or domestic.

  20. Target Detection in SAR Images Based on a Level Set Approach

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Regis C.P.; Medeiros, Fatima N.S.; Ushizima, Daniela M.

    2008-09-01

    This paper introduces a new framework for point target detection in synthetic aperture radar (SAR) images. We focus on the task of locating reflective small regions using alevel set based algorithm. Unlike most of the approaches in image segmentation, we address an algorithm which incorporates speckle statistics instead of empirical parameters and also discards speckle filtering. The curve evolves according to speckle statistics, initially propagating with a maximum upward velocity in homogeneous areas. Our approach is validated by a series of tests on synthetic and real SAR images and compared with three other segmentation algorithms, demonstrating that it configures a novel and efficient method for target detection purpose.

  1. LAND COVER MAPPING USING SENTINEL-1 SAR DATA

    Directory of Open Access Journals (Sweden)

    S. Abdikan

    2016-06-01

    Full Text Available In this paper, the potential of using free-of-charge Sentinel-1 Synthetic Aperture Radar (SAR imagery for land cover mapping in urban areas is investigated. To this aim, we use dual-pol (VV+VH Interferometric Wide swath mode (IW data collected on September 16th 2015 along descending orbit over Istanbul megacity, Turkey. Data have been calibrated, terrain corrected, and filtered by a 5x5 kernel using gamma map approach. During terrain correction by using a 25m resolution SRTM DEM, SAR data has been resampled resulting into a pixel spacing of 20m. Support Vector Machines (SVM method has been implemented as a supervised pixel based image classification to classify the dataset. During the classification, different scenarios have been applied to find out the performance of Sentinel-1 data. The training and test data have been collected from high resolution image of Google Earth. Different combinations of VV and VH polarizations have been analysed and the resulting classified images have been assessed using overall classification accuracy and Kappa coefficient. Results demonstrate that, combining opportunely dual polarization data, the overall accuracy increases up to 93.28% against 73.85% and 70.74% of using individual polarization VV and VH, respectively. Our preliminary analysis points out that dual polarimetric Sentinel-1SAR data can be effectively exploited for producing accurate land cover maps, with relevant advantages for urban planning and management of large cities.

  2. Aoutomatic Oil Spill Detection Using TerraSAR-X Data

    Science.gov (United States)

    Zulipiye, Kaiyoumu; Balik Sanli, Fusun

    2016-07-01

    Oil release into the ocean may affect marine ecosystems and cause environmental pollution. Thus, oil spill detection and identification becomes critical important. Characterized by synoptic view over large regions, remote sensing has been proved to be a reliable tool for oil spill detection. Synthetic Aperture Radar (SAR) imagery shows returned signal that clearly distinguish oil from oil-free surface under optimal wind conditions, which makes it the most frequent used remote sensing technique in oil spill detection. Algorithms of automatic oil spill detection has already been developed for different SAR sensors, including RADARSAT and ENVISAT. In this study, we want to apply automatic oil spill detection algorithms on TerraSAR-X data which is previously developed for ASAR data. The applied methodology includes two steps as segmentation and classification. First segmentation algorithms compiled by C# have been applied under a Bayesian framework adopting a multi-level logistic. After segmentation different classification methods such as feature selection, filter, and embedded selection have been applied. As a result the used classifiers for oil spill detection will be compared, and the complete processing chain will be evaluated.

  3. Applying a particle filtering technique for canola crop growth stage estimation in Canada

    Science.gov (United States)

    Sinha, Abhijit; Tan, Weikai; Li, Yifeng; McNairn, Heather; Jiao, Xianfeng; Hosseini, Mehdi

    2017-10-01

    Accurate crop growth stage estimation is important in precision agriculture as it facilitates improved crop management, pest and disease mitigation and resource planning. Earth observation imagery, specifically Synthetic Aperture Radar (SAR) data, can provide field level growth estimates while covering regional scales. In this paper, RADARSAT-2 quad polarization and TerraSAR-X dual polarization SAR data and ground truth growth stage data are used to model the influence of canola growth stages on SAR imagery extracted parameters. The details of the growth stage modeling work are provided, including a) the development of a new crop growth stage indicator that is continuous and suitable as the state variable in the dynamic estimation procedure; b) a selection procedure for SAR polarimetric parameters that is sensitive to both linear and nonlinear dependency between variables; and c) procedures for compensation of SAR polarimetric parameters for different beam modes. The data was collected over three crop growth seasons in Manitoba, Canada, and the growth model provides the foundation of a novel dynamic filtering framework for real-time estimation of canola growth stages using the multi-sensor and multi-mode SAR data. A description of the dynamic filtering framework that uses particle filter as the estimator is also provided in this paper.

  4. Controlling Data Collection to Support SAR Image Rotation

    Science.gov (United States)

    Doerry, Armin W.; Cordaro, J. Thomas; Burns, Bryan L.

    2008-10-14

    A desired rotation of a synthetic aperture radar (SAR) image can be facilitated by adjusting a SAR data collection operation based on the desired rotation. The SAR data collected by the adjusted SAR data collection operation can be efficiently exploited to form therefrom a SAR image having the desired rotational orientation.

  5. Impact of ionosphere on high-bandwidth chirp in L-band SAR and its mitigation

    Science.gov (United States)

    Nandy, Partha Sarathi; Putrevu, Deepak

    2016-05-01

    There is a trend of SAR imaging at low frequencies (VHF/UHF, L-band) and wide bandwidth, for penetration into foliage for high resolution applications. The propagation of spaceborne radar signals operating at L-band frequency or below can be seriously affected by the ionosphere. While these effects are negligible at X-band, Faraday Rotation and the frequency-dependent path delays can become seriously problematic at L-band. Range delay, interferometric phase bias, range defocussing and Faraday rotation are the most prominent ones. Due to ionospheric effects, blind use of a generic matched filter causes inaccuracies when correlating the received signal with transmitted replica. In this paper we study the effects of frequency dependent path delays in L-band SAR chirp signal due to ionospheric electron density. Also a method to correct ionospheric anomalies without the knowledge of electron content level in a single SAR acquisition is proposed.

  6. SAR Image Complex Pixel Representations

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    Complex pixel values for Synthetic Aperture Radar (SAR) images of uniform distributed clutter can be represented as either real/imaginary (also known as I/Q) values, or as Magnitude/Phase values. Generally, these component values are integers with limited number of bits. For clutter energy well below full-scale, Magnitude/Phase offers lower quantization noise than I/Q representation. Further improvement can be had with companding of the Magnitude value.

  7. Reflectors for SAR performance testing.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2008-01-01

    Synthetic Aperture Radar (SAR) performance testing and estimation is facilitated by observing the system response to known target scene elements. Trihedral corner reflectors and other canonical targets play an important role because their Radar Cross Section (RCS) can be calculated analytically. However, reflector orientation and the proximity of the ground and mounting structures can significantly impact the accuracy and precision with which measurements can be made. These issues are examined in this report.

  8. Water Filters

    Science.gov (United States)

    1988-01-01

    Seeking to find a more effective method of filtering potable water that was highly contaminated, Mike Pedersen, founder of Western Water International, learned that NASA had conducted extensive research in methods of purifying water on board manned spacecraft. The key is Aquaspace Compound, a proprietary WWI formula that scientifically blends various types of glandular activated charcoal with other active and inert ingredients. Aquaspace systems remove some substances; chlorine, by atomic adsorption, other types of organic chemicals by mechanical filtration and still others by catalytic reaction. Aquaspace filters are finding wide acceptance in industrial, commercial, residential and recreational applications in the U.S. and abroad.

  9. Filter apparatus

    Science.gov (United States)

    Kuban, D.P.; Singletary, B.H.; Evans, J.H.

    A plurality of holding tubes are respectively mounted in apertures in a partition plate fixed in a housing receiving gas contaminated with particulate material. A filter cartridge is removably held in each holding tube, and the cartridges and holding tubes are arranged so that gas passes through apertures therein and across the the partition plate while particulate material is collected in the cartridges. Replacement filter cartridges are respectively held in holding canisters mounted on a support plate which can be secured to the aforesaid housing, and screws mounted on said canisters are arranged to push replacement cartridges into the cartridge holding tubes and thereby eject used cartridges therefrom.

  10. Spaceborne SAR Imaging Algorithm for Coherence Optimized.

    Directory of Open Access Journals (Sweden)

    Zhiwei Qiu

    Full Text Available This paper proposes SAR imaging algorithm with largest coherence based on the existing SAR imaging algorithm. The basic idea of SAR imaging algorithm in imaging processing is that output signal can have maximum signal-to-noise ratio (SNR by using the optimal imaging parameters. Traditional imaging algorithm can acquire the best focusing effect, but would bring the decoherence phenomenon in subsequent interference process. Algorithm proposed in this paper is that SAR echo adopts consistent imaging parameters in focusing processing. Although the SNR of the output signal is reduced slightly, their coherence is ensured greatly, and finally the interferogram with high quality is obtained. In this paper, two scenes of Envisat ASAR data in Zhangbei are employed to conduct experiment for this algorithm. Compared with the interferogram from the traditional algorithm, the results show that this algorithm is more suitable for SAR interferometry (InSAR research and application.

  11. Forest biomass estimation from polarimetric SAR interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Mette, T.

    2007-07-01

    Polarimetric SAR interferometry (Pol-InSAR) is a radar remote sensing technique that allows extracting forest heights by means of model-based inversions. Forest biomass is closely related to forest height, and can be derived from it with allometric relations. This work investigates the combination of the two methods to estimate forest biomass from Pol-InSAR. It develops a concept for the use of height-biomass allometry, and outlines the Pol-InSAR height inversion. The methodology is validated against a set of forest inventory data and Pol-InSAR data at L-band of the test site Traunstein. The results allow drawing conclusions on the potential of Pol-InSAR forest biomass missions. (orig.)

  12. Filter This

    Directory of Open Access Journals (Sweden)

    Audrey Barbakoff

    2011-03-01

    Full Text Available In the Library with the Lead Pipe welcomes Audrey Barbakoff, a librarian at the Milwaukee Public Library, and Ahniwa Ferrari, Virtual Experience Manager at the Pierce County Library System in Washington, for a point-counterpoint piece on filtering in libraries. The opinions expressed here are those of the authors, and are not endorsed by their employers. [...

  13. High-Resolution TomoSAR & PS-InSAR Analysis in Urban Areas

    Science.gov (United States)

    Wei, Lianhuan; Liao, Mingsheng; Balz, Timo; Liu, Kang; Jendryke, Michael

    2013-01-01

    The surveillance of urban infrastructures is of great importance. Urban infrastructure monitoring benefits from the launch of the new generation of high-resolution SAR satellites. With high-resolution SAR stacks, even deformation details of different building parts can be observed by PS-InSAR technique. However, high-rise building areas suffer severely from layover effects, which can cause serious phase unwrapping errors in PS-InSAR processing. SAR tomography (TomoSAR) provides a method of overcoming layover effects in urban areas. With tomographic techniques, the 3D distribution of multiple scatterers and their position can be reconstructed. In this poster, the PS-InSAR method is illustrated first, followed with PS-InSAR analysis results in Shanghai. Then, we will describe SAR tomography and why we need TomoSAR, especially in dense cities like Shanghai. Finally, preliminary tomographic results are presented. By combining PS-InSAR and TomoSAR, a 4D dynamic mapping of urban areas could be executed.

  14. Precision Rectification of Airborne SAR Image

    DEFF Research Database (Denmark)

    Dall, Jørgen; Liao, M.; Zhang, Zhe

    1997-01-01

    A simple and direct procedure for the rectification of a certain class of airborne SAR data is presented. The relief displacements of SAR data are effectively removed by means of a digital elevation model and the image is transformed to the ground coordinate system. SAR data from the Danish EMISAR......([7]) is used. The EMISAR produces data with a geometrical resolution of 2.0 meters. The corrected image is tested against photogrammetric control measurements and an accuracy better than 0.5 pixel corresponding to 0.75 meters is obtained. The results indicate promising possibilities...... for the application of SAR data in the difficult process of map revision and updating....

  15. Closed-form mismatched filter synthesis for complementary range response

    Science.gov (United States)

    Bell, Thomas

    2017-04-01

    The combined response of a pair of complementary waveforms has zero range sidelobes and could significantly improve synthetic aperture radar (SAR) image quality by reducing multiplicative noise. However, complementary waveforms may not be practical for SAR imaging for reasons such as Doppler tolerance and unimodular waveform constraints. By using mismatched filters to achieve either a complementary or near-complementary response, two or more practical waveforms could be employed and SAR image quality improved. A closed-form approach was developed that calculates mismatched filters so that the coherent sum of the range responses from each waveform and its corresponding mismatched filter is complementary. A second approach reduced sidelobes while retaining a frequency response close to the waveforms' frequency responses. Images processed using X-band radar data collected under the Air Force Gotcha program exhibited improvements in image quality over those processed using matched filters. The closed-form approach is presented for both complementary and reduced-sidelobe mismatched filters and image quality is quantified. The approach developed in this work offers improved image quality, is suitable for near real-time operation, and is independent of the waveforms.

  16. Sequential Ensembles Tolerant to Synthetic Aperture Radar (SAR Soil Moisture Retrieval Errors

    Directory of Open Access Journals (Sweden)

    Ju Hyoung Lee

    2016-04-01

    Full Text Available Due to complicated and undefined systematic errors in satellite observation, data assimilation integrating model states with satellite observations is more complicated than field measurements-based data assimilation at a local scale. In the case of Synthetic Aperture Radar (SAR soil moisture, the systematic errors arising from uncertainties in roughness conditions are significant and unavoidable, but current satellite bias correction methods do not resolve the problems very well. Thus, apart from the bias correction process of satellite observation, it is important to assess the inherent capability of satellite data assimilation in such sub-optimal but more realistic observational error conditions. To this end, time-evolving sequential ensembles of the Ensemble Kalman Filter (EnKF is compared with stationary ensemble of the Ensemble Optimal Interpolation (EnOI scheme that does not evolve the ensembles over time. As the sensitivity analysis demonstrated that the surface roughness is more sensitive to the SAR retrievals than measurement errors, it is a scope of this study to monitor how data assimilation alters the effects of roughness on SAR soil moisture retrievals. In results, two data assimilation schemes all provided intermediate values between SAR overestimation, and model underestimation. However, under the same SAR observational error conditions, the sequential ensembles approached a calibrated model showing the lowest Root Mean Square Error (RMSE, while the stationary ensemble converged towards the SAR observations exhibiting the highest RMSE. As compared to stationary ensembles, sequential ensembles have a better tolerance to SAR retrieval errors. Such inherent nature of EnKF suggests an operational merit as a satellite data assimilation system, due to the limitation of bias correction methods currently available.

  17. SAR image change detection algorithm based on stationary wavelet and bi-dimensional intrinsic mode function

    Science.gov (United States)

    Huang, S. Q.; Wang, Z. L.; Xie, T. G.; Li, Z. C.

    2017-09-01

    Speckle noise in synthetic aperture radar (SAR) image is produced by the coherent imaging mechanism, which brings a great impact on the change information acquisition of multi-temporal SAR images. Two-dimensional stationary wavelet transform (SWT) and bi-dimensional empirical mode decomposition (BEMD) are the non-stationary signal processing theory of multi-scale transform. According to their implementation process and SAR image characteristic, this paper proposed a new multi-temporal SAR image change detection method based on the combination of the stationary wavelet transform and the bi-dimensional intrinsic mode function (BIMF) features, called SWT-BIMF algorithm. The contribution of the new algorithm includes two aspects. One is the design of the two selections of decomposition features, that is, the speckle noise filtering; another is the selected features to perform the enhance processing, so more effective change information will obtain. The feasibility of the SWT-BIMF algorithm is verified by the measured SAR image data, and good experimental results are obtained.

  18. Feature Fusion Based Road Extraction for HJ-1-C SAR Image

    Directory of Open Access Journals (Sweden)

    Lu Ping-ping

    2014-06-01

    Full Text Available Road network extraction in SAR images is one of the key tasks of military and civilian technologies. To solve the issues of road extraction of HJ-1-C SAR images, a road extraction algorithm is proposed based on the integration of ratio and directional information. Due to the characteristic narrow dynamic range and low signal to noise ratio of HJ-1-C SAR images, a nonlinear quantization and an image filtering method based on a multi-scale autoregressive model are proposed here. A road extraction algorithm based on information fusion, which considers ratio and direction information, is also proposed. By processing Radon transformation, main road directions can be extracted. Cross interferences can be suppressed, and the road continuity can then be improved by the main direction alignment and secondary road extraction. The HJ-1-C SAR image acquired in Wuhan, China was used to evaluate the proposed method. The experimental results show good performance with correctness (80.5% and quality (70.1% when applied to a SAR image with complex content.

  19. A technique for multitarget tracking in synthetic aperture radar spotlight imaging mode based on promoted PHD filtering approach

    Science.gov (United States)

    Daryasafar, N.; Sadeghzadeh, R. A.; Naser-Moghadasi, M.

    2017-02-01

    This paper investigates a new method based on promoted probability hypothesis density (PHD) filtering to simultaneously track several moving targets in data received by synthetic aperture radar (SAR) in spotlight imaging mode. Simultaneous tracking of several targets in the presence of high-density clutters in environment, as the particular capability of the PHD filter, has turned it into a robust approach in SAR to track moving targets. Given the PHD filter function as a sequence of prediction and update steps, it is more reasonable to apply the approach to the data received by the SAR in spotlight imaging mode; however, according to the specified system parameters, such method is not impossible to be implemented using the Stripmap imaging mode. According to simulation results, applying Range Cell Migration Compensation to the raw data received by SAR before tracking operation results in high-quality tracking of moving targets.

  20. Water Filter

    Science.gov (United States)

    1982-01-01

    A compact, lightweight electrolytic water sterilizer available through Ambassador Marketing, generates silver ions in concentrations of 50 to 100 parts per billion in water flow system. The silver ions serve as an effective bactericide/deodorizer. Tap water passes through filtering element of silver that has been chemically plated onto activated carbon. The silver inhibits bacterial growth and the activated carbon removes objectionable tastes and odors caused by addition of chlorine and other chemicals in municipal water supply. The three models available are a kitchen unit, a "Tourister" unit for portable use while traveling and a refrigerator unit that attaches to the ice cube water line. A filter will treat 5,000 to 10,000 gallons of water.

  1. Sentinel-3 SAR Altimetry Toolbox

    Science.gov (United States)

    Benveniste, Jerome; Lucas, Bruno; DInardo, Salvatore

    2015-04-01

    The prime objective of the SEOM (Scientific Exploitation of Operational Missions) element is to federate, support and expand the large international research community that the ERS, ENVISAT and the Envelope programmes have build up over the last 20 years for the future European operational Earth Observation missions, the Sentinels. Sentinel-3 builds directly on a proven heritage of ERS-2 and Envisat, and CryoSat-2, with a dual-frequency (Ku and C band) advanced Synthetic Aperture Radar Altimeter (SRAL) that provides measurements at a resolution of ~300m in SAR mode along track. Sentinel-3 will provide exact measurements of sea-surface height along with accurate topography measurements over sea ice, ice sheets, rivers and lakes. The first of the two Sentinels is expected to be launched in early 2015. The current universal altimetry toolbox is BRAT (Basic Radar Altimetry Toolbox) which can read all previous and current altimetry mission's data, but it does not have the capabilities to read the upcoming Sentinel-3 L1 and L2 products. ESA will endeavour to develop and supply this capability to support the users of the future Sentinel-3 SAR Altimetry Mission. BRAT is a collection of tools and tutorial documents designed to facilitate the processing of radar altimetry data. This project started in 2005 from the joint efforts of ESA (European Space Agency) and CNES (Centre National d'Etudes Spatiales), and it is freely available at http://earth.esa.int/brat. The tools enable users to interact with the most common altimetry data formats, the BratGUI is the front-end for the powerful command line tools that are part of the BRAT suite. BRAT can also be used in conjunction with Matlab/IDL (via reading routines) or in C/C++/Fortran via a programming API, allowing the user to obtain desired data, bypassing the data-formatting hassle. BRAT can be used simply to visualise data quickly, or to translate the data into other formats such as netCDF, ASCII text files, KML (Google Earth

  2. SAR/MTI on small airborne platforms

    NARCIS (Netherlands)

    Rossum, W.L. van; Vermeulen, B.C.B.

    2006-01-01

    A small SAR-MTI system is being developed at TNO, aimed at deployment on tactical UAV. The system makes use of modern front-end technology, to provide flexible SAR imaging and MTI modes. Major design goals are 50 kg weight, 500 W power consumption and 50 cm resolution in order to comply with typical

  3. A Simple Model for a SARS Epidemic

    Science.gov (United States)

    Ang, Keng Cheng

    2004-01-01

    In this paper, we examine the use of an ordinary differential equation in modelling the SARS outbreak in Singapore. The model provides an excellent example of using mathematics in a real life situation. The mathematical concepts involved are accessible to students with A level Mathematics backgrounds. Data for the SARS epidemic in Singapore are…

  4. SAR change detection techniques and applications

    NARCIS (Netherlands)

    Dekker, R.J.

    2005-01-01

    ABSTRACT: Change detection, the comparison of remote sensing images from different moments in time, is an important technique in environmental earth observation and security. SAR change detection is useful when weather and light conditions are unfavourable. Five methods of SAR change detection are

  5. Geologic mapping in Greenland with polarimetric SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Madsen, Søren Nørvang; Brooks, C. K.

    1995-01-01

    The application of synthetic aperture radar (SAR) for geologic mapping in Greenland is investigated by the Danish Center for Remote Sensing (DCRS) in co-operation with the Danish Lithosphere Centre (DLC). In 1994 a pilot project was conducted in East Greenland. The Danish airborne SAR, EMISAR...

  6. Real-time brute force SAR processing

    NARCIS (Netherlands)

    Vlothuizen, W.J.; Ditzel, M.

    2009-01-01

    This paper presents a brute force method to perform real-time SAR processing. The method has several advantages over traditional so-called fast SAR implementations, as it does not make any approximations to alleviate the processing burden. However, the method does allow efficient implementation on

  7. Deep learning for SAR image formation

    Science.gov (United States)

    Mason, Eric; Yonel, Bariscan; Yazici, Birsen

    2017-04-01

    The recent success of deep learning has lead to growing interest in applying these methods to signal processing problems. This paper explores the applications of deep learning to synthetic aperture radar (SAR) image formation. We review deep learning from a perspective relevant to SAR image formation. Our objective is to address SAR image formation in the presence of uncertainties in the SAR forward model. We present a recurrent auto-encoder network architecture based on the iterative shrinkage thresholding algorithm (ISTA) that incorporates SAR modeling. We then present an off-line training method using stochastic gradient descent and discuss the challenges and key steps of learning. Lastly, we show experimentally that our method can be used to form focused images in the presence of phase uncertainties. We demonstrate that the resulting algorithm has faster convergence and decreased reconstruction error than that of ISTA.

  8. Geometric calibration of ERS satellite SAR images

    DEFF Research Database (Denmark)

    Mohr, Johan Jacob; Madsen, Søren Nørvang

    2001-01-01

    Geometric calibration of the European Remote Sensing (ERS) Satellite synthetic aperture radar (SAR) slant range images is important in relation to mapping areas without ground reference points and also in relation to automated processing. The relevant SAR system parameters are discussed and calib......Geometric calibration of the European Remote Sensing (ERS) Satellite synthetic aperture radar (SAR) slant range images is important in relation to mapping areas without ground reference points and also in relation to automated processing. The relevant SAR system parameters are discussed...... on a seven-year ERS-1 and a four-year ERS-2 time series, the long term stability is found to be sufficient to allow a single calibration covering the entire mission period. A descending and an ascending orbit tandem pair of the ESA calibration site on Flevoland, suitable for calibration of ERS SAR processors...

  9. Composite SAR imaging using sequential joint sparsity

    Science.gov (United States)

    Sanders, Toby; Gelb, Anne; Platte, Rodrigo B.

    2017-06-01

    This paper investigates accurate and efficient ℓ1 regularization methods for generating synthetic aperture radar (SAR) images. Although ℓ1 regularization algorithms are already employed in SAR imaging, practical and efficient implementation in terms of real time imaging remain a challenge. Here we demonstrate that fast numerical operators can be used to robustly implement ℓ1 regularization methods that are as or more efficient than traditional approaches such as back projection, while providing superior image quality. In particular, we develop a sequential joint sparsity model for composite SAR imaging which naturally combines the joint sparsity methodology with composite SAR. Our technique, which can be implemented using standard, fractional, or higher order total variation regularization, is able to reduce the effects of speckle and other noisy artifacts with little additional computational cost. Finally we show that generalizing total variation regularization to non-integer and higher orders provides improved flexibility and robustness for SAR imaging.

  10. Operational SAR Data Processing in GIS Environments for Rapid Disaster Mapping

    Science.gov (United States)

    Bahr, Thomas

    2014-05-01

    The use of SAR data has become increasingly popular in recent years and in a wide array of industries. Having access to SAR can be highly important and critical especially for public safety. Updating a GIS with contemporary information from SAR data allows to deliver a reliable set of geospatial information to advance civilian operations, e.g. search and rescue missions. SAR imaging offers the great advantage, over its optical counterparts, of not being affected by darkness, meteorological conditions such as clouds, fog, etc., or smoke and dust, frequently associated with disaster zones. In this paper we present the operational processing of SAR data within a GIS environment for rapid disaster mapping. For this technique we integrated the SARscape modules for ENVI with ArcGIS®, eliminating the need to switch between software packages. Thereby the premier algorithms for SAR image analysis can be directly accessed from ArcGIS desktop and server environments. They allow processing and analyzing SAR data in almost real time and with minimum user interaction. This is exemplified by the November 2010 flash flood in the Veneto region, Italy. The Bacchiglione River burst its banks on Nov. 2nd after two days of heavy rainfall throughout the northern Italian region. The community of Bovolenta, 22 km SSE of Padova, was covered by several meters of water. People were requested to stay in their homes; several roads, highways sections and railroads had to be closed. The extent of this flooding is documented by a series of Cosmo-SkyMed acquisitions with a GSD of 2.5 m (StripMap mode). Cosmo-SkyMed is a constellation of four Earth observation satellites, allowing a very frequent coverage, which enables monitoring using a very high temporal resolution. This data is processed in ArcGIS using a single-sensor, multi-mode, multi-temporal approach consisting of 3 steps: (1) The single images are filtered with a Gamma DE-MAP filter. (2) The filtered images are geocoded using a reference

  11. Digital filters

    CERN Document Server

    Hamming, Richard W

    1997-01-01

    Digital signals occur in an increasing number of applications: in telephone communications; in radio, television, and stereo sound systems; and in spacecraft transmissions, to name just a few. This introductory text examines digital filtering, the processes of smoothing, predicting, differentiating, integrating, and separating signals, as well as the removal of noise from a signal. The processes bear particular relevance to computer applications, one of the focuses of this book.Readers will find Hamming's analysis accessible and engaging, in recognition of the fact that many people with the s

  12. Filtered or Unfiltered?

    Science.gov (United States)

    Curry, Ann; Haycock, Ken

    2001-01-01

    Discusses results of a survey questionnaire of public and school libraries that investigated the use of Internet filtering software. Considers filter alternatives; reasons for filtering or not filtering; brand names; satisfaction with site blocking; satisfaction with the decision to install filter software; and guidelines for considering filters.…

  13. Validation of burst overlapping for ALOS-2 PALSAR-2 ScanSAR-ScanSAR interferometry

    Science.gov (United States)

    Natsuaki, Ryo; Motohka, Takeshi; Ohki, Masato; Watanabe, Manabu; Suzuki, Shinichi

    2016-10-01

    The Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) aboard the Advanced Land Observing Satellite- 2 (ALOS-2, "DAICHI-2") is the latest L-band spaceborne synthetic aperture radar (SAR). PALSAR-2 observes the world mainly with 10 m resolution / 70 km swath Stripmap mode and 25 m resolution / 350 km swath ScanSAR mode. The 3-m resolution Stripmap mode is mainly used upon Japan. 350 km ScanSAR observation could detect large scale deformation e.g., the Mw 7.8 Gorkha, Nepal earthquake and its aftershocks in 2015. ALOS-2 ScanSAR is the first one that supports ScanSAR-ScanSAR interferometry in L-band spaceborne SAR. However, because of the parameter setting error for the orbit estimation, ALOS-2 PALSAR-2 ScanSAR could achieve little number of interferometric pair until the software modification on February 8, 2015. That is, the burst overlap timing required for the interferometric analysis was insufficient and it depends on the observation date. In this paper, we report the investigation results of this case and discuss the current status of the ALOS-2 ScanSAR InSAR. Some archives achieved before February 8, 2015 can be used for interferometric analysis with after Feb. 8. However, most of them have no interferometric pair. We also report that the archives acquired after February 8, have enough burst overlapping.

  14. High Resolution TomoSAR & PS-InSAR Analysis in Urban Areas

    Science.gov (United States)

    Wei, Lianhuan; Liao, Mingsheng; Balz, Timo; Liu, Kang; Jendryke, Michael

    2013-01-01

    The surveillance of urban infrastructures is of great importance. Urban infrastructure monitoring benefits from the launch of the new generation of high-resolution SAR satellites. With high-resolution SAR stacks, even deformation details of different building parts can be observed. The PS-InSAR technique has become a favorable tool for urban area subsidence monitoring, and it has been demonstrated that millimeter accuracy can be achieved. However, high-rise building areas suffer severely from layover effects, which can cause serious phase unwrapping errors. SAR tomography provides a method of overcoming layover effects in urban areas. With tomographic techniques, the 3D distribution of multiple scatterers and their position can be reconstructed. In this paper, the PS-InSAR method is briefly described first, followed by PS-InSAR analysis results in Shanghai. Then, we will describe SAR tomography and why we need TomoSAR, especially in dense cities like Shanghai. Finally, preliminary tomographic results about Shanghai are presented. By combining PS-InSAR and TomoSAR, a 4D dynamic mapping of urban areas could be executed.

  15. Extraction of Coastlines with Fuzzy Approach Using SENTINEL-1 SAR Image

    Science.gov (United States)

    Demir, N.; Kaynarca, M.; Oy, S.

    2016-06-01

    Coastlines are important features for water resources, sea products, energy resources etc. Coastlines are changed dynamically, thus automated methods are necessary for analysing and detecting the changes along the coastlines. In this study, Sentinel-1 C band SAR image has been used to extract the coastline with fuzzy logic approach. The used SAR image has VH polarisation and 10x10m. spatial resolution, covers 57 sqkm area from the south-east of Puerto-Rico. Additionally, radiometric calibration is applied to reduce atmospheric and orbit error, and speckle filter is used to reduce the noise. Then the image is terrain-corrected using SRTM digital surface model. Classification of SAR image is a challenging task since SAR and optical sensors have very different properties. Even between different bands of the SAR sensors, the images look very different. So, the classification of SAR image is difficult with the traditional unsupervised methods. In this study, a fuzzy approach has been applied to distinguish the coastal pixels than the land surface pixels. The standard deviation and the mean, median values are calculated to use as parameters in fuzzy approach. The Mean-standard-deviation (MS) Large membership function is used because the large amounts of land and ocean pixels dominate the SAR image with large mean and standard deviation values. The pixel values are multiplied with 1000 to easify the calculations. The mean is calculated as 23 and the standard deviation is calculated as 12 for the whole image. The multiplier parameters are selected as a: 0.58, b: 0.05 to maximize the land surface membership. The result is evaluated using airborne LIDAR data, only for the areas where LIDAR dataset is available and secondly manually digitized coastline. The laser points which are below 0,5 m are classified as the ocean points. The 3D alpha-shapes algorithm is used to detect the coastline points from LIDAR data. Minimum distances are calculated between the LIDAR points of

  16. Improved TEC retrieval based on spaceborne PolSAR data

    Science.gov (United States)

    Wang, Cheng; Liu, Lu; Chen, Liang; Feng, Jian; Zhao, Hai-Sheng

    2017-03-01

    It is well known that for Earth observations, the spaceborne synthetic aperture radar (SAR) systems at L-band can be seriously affected by the ionosphere. Fortunately, the destructive ionospheric information, total electron content (TEC), can be retrieved and removed by model inversion from SAR echoes and becomes a subject of interest for ionospheric research. Considering the system noise and channel phase imbalance, this paper focuses on accurate TEC retrieval from the Faraday rotation angle, which is embedded in Advanced Land Observing Satellite phased array L-band synthetic aperture radar (PALSAR) full-pol data. For the consideration of denoising, averaging filtering is widely used in existing studies to remove the system noise. In order to further reduce the noise effects, a fast total variation (FTV) denoising method is applied in this paper. By using the PALSAR full-pol data sets, a series of simulation results show that the FTV denoising is effective for noise suppression and markedly reduce the standard deviation. For the error of channel phase imbalance, a new Faraday estimator based on the covariance matrix of circular basis is proposed. Compared with previous estimators, theoretical analysis and simulation results show that this new estimator can give the best performance for sensors that are dominated by channel phase imbalance errors. Thus, the proposed estimator can be a candidate method for TEC retrieval when phase imbalance is the domain error.

  17. Sea surface slicks measured by SAR

    Energy Technology Data Exchange (ETDEWEB)

    Trivero, P. [Alessandria Univ. del Piemonte Orientale, Alessandri (Italy). Dipt. di Scienze e Tecnologie Avanzate; Fiscella, B. [Turin Univ., Turin (Italy). Dipt. di Fisica Generale; Pavese, P. [Consiglio Nazionale delle Ricerche, Istituto di Cosmogeofisica, Turin (Italy)

    2001-02-01

    The Synthetic Aperture Radar (SAR) system capability to detect and characterize marine surface slicks was tested during the SAR-580 experiment in the northern Adriatic Sea, offshore the Venice coast, in October 1990. Two small artificial slicks of oleyl alcohol were produced in an area around the oceanographic platform of the Italian National Research Council (CNR). The oleyl alcohol produces a damping of the sea centimetric waves, which has been measured by an airborne two band (C and X) SAR, by a tower based 3 band (L, S and C) scatterometer and by a wave gauge, installed on board the platform, which measures the instantaneous sea surface elevation in the range form gravity up to capillary waves. The good agreement among measures proves that multi-frequency SAR is able to detect and characterized sea surface films. Slicks in SAR images taken during SIR-C/X-SAR mission in 1994 have been analysed on the basis of these results and L-band measurements of spatial attenuation near the borders of the slicks have been done, in order to test the slicks detectability using single-band SAR images.

  18. SARS - infectious disease of 21st century

    Directory of Open Access Journals (Sweden)

    Tjandra Y. Aditama

    2005-03-01

    Full Text Available Severe acute respiratory syndrome (SARS is an emerging viral infectious disease. According to the World Health Organization, a suspected case of SARS is defined as documented fever (temperature >38°C, lower respiratory tract symptoms, and contact with a person believed to have had SARS or history of travel to an area of documented transmission. A probable case is a suspected case with chest radiographic findings of pneumonia, acute respiratory distress syndrome (ARDS, or an unexplained respiratory illness resulting in death, with autopsy findings of ARDS without identifiable cause. In this article some SARS epidemiological data in Indonesia will also presented. There are 7 SARS suspected cases and 2 probable cases were registered in Indonesia on the period of 1 March to 9 July 2003, and no more cases were reported after that time. How will be SARS progression in the future will be a subject of discussion among scientist, and we will have to wait and be prepared for any development might occur. (Med J Indones 2005; 14: 59-63Keywords: SARS, Case Definition, Etiology, Indonesia

  19. A brief review on tsunami early warning detection using BPR approach and post analysis by SAR satellite dataset

    Directory of Open Access Journals (Sweden)

    Sudhir Kumar Chaturvedi

    2017-06-01

    Full Text Available Tsunami early warning systems have provided to be the extreme importance after the tsunami that hit Japan in March 2011. This research article presents a case study based on the tsunami detection using Bottom Pressure Rate (BPR measurement and the post the analysis using the SAR datasets. A final decision based system using BPR has been studied to carry out the measurements of tsunami wave parameters. SAR based study has also been carried out for the post tsunami studies. Wiener filters are utilized to remove the speckle noise presents in imagery. Future scope of this work has also been proposed.

  20. Enhanced Assimilation of InSAR Displacement and Well Data for Groundwater Monitoring

    Science.gov (United States)

    Abdullin, A.; Jonsson, S.

    2016-12-01

    Ground deformation related to aquifer exploitation can cause damage to buildings and infrastructure leading to major economic losses and sometimes even loss of human lives. Understanding reservoir behavior helps in assessing possible future ground movement and water depletion hazard of a region under study. We have developed an InSAR-based data assimilation framework for groundwater reservoirs that efficiently incorporates InSAR data for improved reservoir management and forecasts. InSAR displacement data are integrated with the groundwater modeling software MODFLOW using ensemble-based assimilation approaches. We have examined several Ensemble Methods for updating model parameters such as hydraulic conductivity and model variables like pressure head while simultaneously providing an estimate of the uncertainty. A realistic three-dimensional aquifer model was built to demonstrate the capability of the Ensemble Methods incorporating InSAR-derived displacement measurements. We find from these numerical tests that including both ground deformation and well water level data as observations improves the RMSE of the hydraulic conductivity estimate by up to 20% comparing to using only one type of observations. The RMSE estimation of this property after the final time step is similar for Ensemble Kalman Filter (EnKF), Ensemble Smoother (ES) and ES with multiple data assimilation (ES-MDA) methods. The results suggest that the high spatial and temporal resolution subsidence observations from InSAR are very helpful for accurately quantifying hydraulic parameters. We have tested the framework on several different examples and have found good performance in improving aquifer properties estimation, which should prove useful for groundwater management. Our ongoing work focuses on assimilating real InSAR-derived time series and hydraulic head data for calibrating and predicting aquifer properties of basin-wide groundwater systems.

  1. Land Subsidence Monitoring Using PS-InSAR Technique for L-Band SAR Data

    Science.gov (United States)

    Thapa, S.; Chatterjee, R. S.; Singh, K. B.; Kumar, D.

    2016-10-01

    Differential SAR-Interferometry (D-InSAR) is one of the potential source to measure land surface motion induced due to underground coal mining. However, this technique has many limitation such as atmospheric in homogeneities, spatial de-correlation, and temporal decorrelation. Persistent Scatterer Interferometry synthetic aperture radar (PS-InSAR) belongs to a family of time series InSAR technique, which utilizes the properties of some of the stable natural and anthropogenic targets which remain coherent over long time period. In this study PS-InSAR technique has been used to monitor land subsidence over selected location of Jharia Coal field which has been correlated with the ground levelling measurement. This time series deformation observed using PS InSAR helped us to understand the nature of the ground surface deformation due to underground mining activity.

  2. Wave directional spectrum from SAR imagery

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, A.A.; Sarma, Y.V.B.; Menon, H.B.; Vethamony, P.

    and surface wind waves, especially swell. SAR is also useful for ship detection Ocean waves are weakly 10 A.A. Fernandes et al. imaged and can be recognized from SAR imagery from their fine "finger print" like signature. In contrast with ocean waves.../internal waves by all types of radar including ship radar, Real Aperture Radar (RAR) mounted on aeroplanes and Synthetic. Aperture Radar (SAR) mounted on satellites, is by modulation of the back-scatter from short Bragg resonant capillary-gravity waves...

  3. Offshore wind mapping Mediterranean area using SAR

    DEFF Research Database (Denmark)

    Calaudi, Rosamaria; Arena, Felice; Badger, Merete

    2013-01-01

    Satellite observations of the ocean surface, for example from Synthetic Aperture Radars (SAR), provide information about the spatial wind variability over large areas. This is of special interest in the Mediterranean Sea, where spatial wind information is only provided by sparse buoys, often...... with long periods of missing data. Here, we focus on evaluating the use of SAR for offshore wind mapping. Preliminary results from the analysis of SAR-based ocean winds in Mediterranean areas show interesting large scale wind flow features consistent with results from previous studies using numerical models...

  4. NASA/JPL Aircraft SAR Workshop Proceedings

    Science.gov (United States)

    Donovan, N. (Editor); Evans, D. L. (Editor); Held, D. N. (Editor)

    1985-01-01

    Speaker-supplied summaries of the talks given at the NASA/JPL Aircraft SAR Workshop on February 4 and 5, 1985, are provided. These talks dealt mostly with composite quadpolarization imagery from a geologic or ecologic prespective. An overview and summary of the system characteristics of the L-band synthetic aperture radar (SAR) flown on the NASA CV-990 aircraft are included as supplementary information. Other topics ranging from phase imagery and interferometric techniques classifications of specific areas, and the potentials and limitations of SAR imagery in various applications are discussed.

  5. SAR ATR Based on Convolutional Neural Network

    Directory of Open Access Journals (Sweden)

    Tian Zhuangzhuang

    2016-06-01

    Full Text Available This study presents a new method of Synthetic Aperture Radar (SAR image target recognition based on a convolutional neural network. First, we introduce a class separability measure into the cost function to improve this network’s ability to distinguish between categories. Then, we extract SAR image features using the improved convolutional neural network and classify these features using a support vector machine. Experimental results using moving and stationary target acquisition and recognition SAR datasets prove the validity of this method.

  6. Structured filtering

    Science.gov (United States)

    Granade, Christopher; Wiebe, Nathan

    2017-08-01

    A major challenge facing existing sequential Monte Carlo methods for parameter estimation in physics stems from the inability of existing approaches to robustly deal with experiments that have different mechanisms that yield the results with equivalent probability. We address this problem here by proposing a form of particle filtering that clusters the particles that comprise the sequential Monte Carlo approximation to the posterior before applying a resampler. Through a new graphical approach to thinking about such models, we are able to devise an artificial-intelligence based strategy that automatically learns the shape and number of the clusters in the support of the posterior. We demonstrate the power of our approach by applying it to randomized gap estimation and a form of low circuit-depth phase estimation where existing methods from the physics literature either exhibit much worse performance or even fail completely.

  7. AUTOMATIC INTERPRETATION OF HIGH RESOLUTION SAR IMAGES: FIRST RESULTS OF SAR IMAGE SIMULATION FOR SINGLE BUILDINGS

    Directory of Open Access Journals (Sweden)

    J. Tao

    2012-09-01

    Full Text Available Due to the all-weather data acquisition capabilities, high resolution space borne Synthetic Aperture Radar (SAR plays an important role in remote sensing applications like change detection. However, because of the complex geometric mapping of buildings in urban areas, SAR images are often hard to interpret. SAR simulation techniques ease the visual interpretation of SAR images, while fully automatic interpretation is still a challenge. This paper presents a method for supporting the interpretation of high resolution SAR images with simulated radar images using a LiDAR digital surface model (DSM. Line features are extracted from the simulated and real SAR images and used for matching. A single building model is generated from the DSM and used for building recognition in the SAR image. An application for the concept is presented for the city centre of Munich where the comparison of the simulation to the TerraSAR-X data shows a good similarity. Based on the result of simulation and matching, special features (e.g. like double bounce lines, shadow areas etc. can be automatically indicated in SAR image.

  8. Evaluation of InSAR and TomoSAR for Monitoring Deformations Caused by Mining in a Mountainous Area with High Resolution Satellite-Based SAR

    Directory of Open Access Journals (Sweden)

    Donglie Liu

    2014-02-01

    Full Text Available Interferometric Synthetic Aperture Radar (InSAR and Differential Interferometric Synthetic Aperture Radar (DInSAR have shown numerous applications for subsidence monitoring. In the past 10 years, the Persistent Scatterer InSAR (PSI and Small BAseline Subset (SBAS approaches were developed to overcome the problem of decorrelation and atmospheric effects, which are common in interferograms. However, DInSAR or PSI applications in rural areas, especially in mountainous regions, can be extremely challenging. In this study we have employed a combined technique, i.e., SBAS-DInSAR, to a mountainous area that is severely affected by mining activities. In addition, L-band (ALOS and C-band (ENVISAT data sets, 21 TerraSAR-X images provided by German Aerospace Center (DLR with a high resolution have been used. In order to evaluate the ability of TerraSAR-X for mining monitoring, we present a case study of TerraSAR-X SAR images for Subsidence Hazard Boundary (SHB extraction. The resulting data analysis gives an initial evaluation of InSAR applications within a mountainous region where fast movements and big phase gradients are common. Moreover, the experiment of four-dimension (4-D Tomography SAR (TomoSAR for structure monitoring inside the mining area indicates a potential near all-wave monitoring, which is an extension of conventional InSAR.

  9. MiTAP for SARS Detection

    National Research Council Canada - National Science Library

    Damianos, Laurie E; Bayer, Samuel; Chisholm, Michael A; Henderson, John; Hirschman, Lynette; Morgan, William; Ubaldino, Marc; Zarrella, Guido; Wilson, V, James M; Polyak, Marat G

    2006-01-01

    The MiTAP prototype for SARS detection uses human language technology for detecting, monitoring, and analyzing potential indicators of infectious disease outbreaks and reasoning for issuing warnings and alerts...

  10. Attribute Learning for SAR Image Classification

    Directory of Open Access Journals (Sweden)

    Chu He

    2017-04-01

    Full Text Available This paper presents a classification approach based on attribute learning for high spatial resolution Synthetic Aperture Radar (SAR images. To explore the representative and discriminative attributes of SAR images, first, an iterative unsupervised algorithm is designed to cluster in the low-level feature space, where the maximum edge response and the ratio of mean-to-variance are included; a cross-validation step is applied to prevent overfitting. Second, the most discriminative clustering centers are sorted out to construct an attribute dictionary. By resorting to the attribute dictionary, a representation vector describing certain categories in the SAR image can be generated, which in turn is used to perform the classifying task. The experiments conducted on TerraSAR-X images indicate that those learned attributes have strong visual semantics, which are characterized by bright and dark spots, stripes, or their combinations. The classification method based on these learned attributes achieves better results.

  11. A New Approach for SAR Image Denoising

    National Research Council Canada - National Science Library

    Murali Mohan Babu Y; Subramanyam M V; Giri Prasad M N

    2015-01-01

      In synthetic aperture radar (SAR) imaging, the transmitted pulses from space born antenna interacts with ground objects and returned energy or back scattered energy will be collected to get backscattered image...

  12. Satellite sar detection of hurricane helene (2006)

    DEFF Research Database (Denmark)

    Ju, Lian; Cheng, Yongcun; Xu, Qing

    2013-01-01

    In this paper, the wind structure of hurricane Helene (2006) over the Atlantic Ocean is investigated from a C-band RADARSAT-1 synthetic aperture radar (SAR) image acquired on 20 September 2006. First, the characteristics, e.g., the center, scale and area of the hurricane eye (HE) are determined....... There is a good agreement between the SAR-estimated HE center location and the best track data from the National Hurricane Center. The wind speeds at 10 m above the ocean surface are also retrieved from the SAR data using the geophysical model function (GMF), CMOD5, and compared with in situ wind speed...... observations from the stepped frequency microwave radiometer (SFMR) on NOAA P3 aircraft. All the results show the capability of hurricane monitoring by satellite SAR. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE)....

  13. Advanced Antenna for Digital Beamforming SAR Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop a wideband (500 MHz) L-band phased-array antenna for airborne Synthetic Aperture Radar (SAR) applications based on a novel approach that will make possible...

  14. AUTOMATIC SHIP DETECTION IN SINGLE-POL SAR IMAGES USING TEXTURE FEATURES IN ARTIFICIAL NEURAL NETWORKS

    Directory of Open Access Journals (Sweden)

    E. Khesali

    2015-12-01

    Full Text Available This paper presents a novel method for detecting ships from high-resolution synthetic aperture radar (SAR images. This method categorizes ship targets from single-pol SAR images using texture features in artificial neural networks. As such, the method tries to overcome the lack of an operational solution that is able to reliably detect ships with one SAR channel. The method has the following three main stages: 1 feature extraction; 2 feature selection; and 3 ship detection. The first part extracts different texture features from SAR image. These textures include occurrence and co occurrence measures with different window sizes. Then, best features are selected. Finally, the artificial neural network is used to extract ship pixels from sea ones. In post processing stage some morphological filters are used to improve the result. The effectiveness of the proposed method is verified using Sentinel-1 data in VV polarization. Experimental results indicate that the proposed algorithm can be implemented with time-saving, high precision ship extraction, feature analysis, and detection. The results also show that using texture features the algorithm properly discriminates speckle noise from ships.

  15. Observations and Mitigation of RFI in ALOS PALSAR SAR Data; Implications for the Desdyni Mission

    Science.gov (United States)

    Rosen, Paul A.; Hensley, Scott; Le, Charles

    2008-01-01

    Initial examination of ALOS PALSAR synthetic aperture radar (SAR) data has indicated significant radio frequency interference (RFI) in several geographic locations around the world. RFI causes significant reduction in image contrast, introduces periodic and quasi-periodic image artifacts, and introduces significant phase noise in repeat pass interferometric data reduction. The US National Research Council Decadal Survey of Earth Science has recommended DESDynI, a Deformation, Ecosystems, and Dynamics of Ice satellite mission comprising an L-band polarimetric radar configured for repeat pass interferometry. There is considerable interest internationally in other future L-band and lower frequency systems as well. Therefore the issues of prevalence and possibilities of mitigation of RFI in these crowded frequency bands is of considerable interest. RFI is observed in ALOS PALSAR in California, USA, and in southern Egypt in data examined to date. Application of several techniques for removing it from the data prior to SAR image formation, ranging from straightforward spectral normalization to time-domain, multi-phase filtering techniques are considered. Considerable experience has been gained from the removal of RFI from P-band acquired by the GeoSAR system. These techniques applied to the PALSAR data are most successful when the bandwidth of any particular spectral component of the RFI is narrow. Performance impacts for SAR imagery and interferograms are considered in the context of DESDynI measurement requirements.

  16. Convergent Filter Bases

    Directory of Open Access Journals (Sweden)

    Coghetto Roland

    2015-09-01

    Full Text Available We are inspired by the work of Henri Cartan [16], Bourbaki [10] (TG. I Filtres and Claude Wagschal [34]. We define the base of filter, image filter, convergent filter bases, limit filter and the filter base of tails (fr: filtre des sections.

  17. Rayleigh-maximum-likelihood bilateral filter for ultrasound image enhancement.

    Science.gov (United States)

    Li, Haiyan; Wu, Jun; Miao, Aimin; Yu, Pengfei; Chen, Jianhua; Zhang, Yufeng

    2017-04-17

    Ultrasound imaging plays an important role in computer diagnosis since it is non-invasive and cost-effective. However, ultrasound images are inevitably contaminated by noise and speckle during acquisition. Noise and speckle directly impact the physician to interpret the images and decrease the accuracy in clinical diagnosis. Denoising method is an important component to enhance the quality of ultrasound images; however, several limitations discourage the results because current denoising methods can remove noise while ignoring the statistical characteristics of speckle and thus undermining the effectiveness of despeckling, or vice versa. In addition, most existing algorithms do not identify noise, speckle or edge before removing noise or speckle, and thus they reduce noise and speckle while blurring edge details. Therefore, it is a challenging issue for the traditional methods to effectively remove noise and speckle in ultrasound images while preserving edge details. To overcome the above-mentioned limitations, a novel method, called Rayleigh-maximum-likelihood switching bilateral filter (RSBF) is proposed to enhance ultrasound images by two steps: noise, speckle and edge detection followed by filtering. Firstly, a sorted quadrant median vector scheme is utilized to calculate the reference median in a filtering window in comparison with the central pixel to classify the target pixel as noise, speckle or noise-free. Subsequently, the noise is removed by a bilateral filter and the speckle is suppressed by a Rayleigh-maximum-likelihood filter while the noise-free pixels are kept unchanged. To quantitatively evaluate the performance of the proposed method, synthetic ultrasound images contaminated by speckle are simulated by using the speckle model that is subjected to Rayleigh distribution. Thereafter, the corrupted synthetic images are generated by the original image multiplied with the Rayleigh distributed speckle of various signal to noise ratio (SNR) levels and

  18. SARS: Key factors in crisis management.

    Science.gov (United States)

    Tseng, Hsin-Chao; Chen, Thai-Form; Chou, Shieu-Ming

    2005-03-01

    This study was conducted at a single hospital selected in Taipei during the SARS (Severe Acute Respiratory Syndrome) outbreak from March to July, 2003 in Taiwan. During this period of time, 104 SARS patients were admitted to the hospital. There were no negative reports related to the selected hospital despite its being located right in the center of an area struck by the epidemic. The purpose of this study was to identify the key factors enabling the hospital to survive SARS unscathed. Data were collected from in-depth interviews with the nursing directors and nursing managers of the SARS units, along with a review of relevant hospital documents. The five key elements identified as survival factors during this SARS crisis are as follows: 1. good control of timing for crisis management, 2. careful decision-making, 3. thorough implementation, 4. effective communication, and 5. trust between management and employees. The results of this study reconfirmed the selected hospital as a model for good crisis management during the SARS epidemic.

  19. SARS among Critical Care Nurses, Toronto

    Science.gov (United States)

    McGeer, Allison; Henry, Bonnie; Ofner, Marianna; Rose, David; Hlywka, Tammy; Levie, Joanne; McQueen, Jane; Smith, Stephanie; Moss, Lorraine; Smith, Andrew; Green, Karen; Walter, Stephen D.

    2004-01-01

    To determine factors that predispose or protect healthcare workers from severe acute respiratory syndrome (SARS), we conducted a retrospective cohort study among 43 nurses who worked in two Toronto critical care units with SARS patients. Eight of 32 nurses who entered a SARS patient’s room were infected. The probability of SARS infection was 6% per shift worked. Assisting during intubation, suctioning before intubation, and manipulating the oxygen mask were high-risk activities. Consistently wearing a mask (either surgical or particulate respirator type N95) while caring for a SARS patient was protective for the nurses, and consistent use of the N95 mask was more protective than not wearing a mask. Risk was reduced by consistent use of a surgical mask, but not significantly. Risk was lower with consistent use of a N95 mask than with consistent use of a surgical mask. We conclude that activities related to intubation increase SARS risk and use of a mask (particularly a N95 mask) is protective. PMID:15030692

  20. Ionospheric Specifications for SAR Interferometry (ISSI)

    Science.gov (United States)

    Pi, Xiaoqing; Chapman, Bruce D; Freeman, Anthony; Szeliga, Walter; Buckley, Sean M.; Rosen, Paul A.; Lavalle, Marco

    2013-01-01

    The ISSI software package is designed to image the ionosphere from space by calibrating and processing polarimetric synthetic aperture radar (PolSAR) data collected from low Earth orbit satellites. Signals transmitted and received by a PolSAR are subject to the Faraday rotation effect as they traverse the magnetized ionosphere. The ISSI algorithms combine the horizontally and vertically polarized (with respect to the radar system) SAR signals to estimate Faraday rotation and ionospheric total electron content (TEC) with spatial resolutions of sub-kilometers to kilometers, and to derive radar system calibration parameters. The ISSI software package has been designed and developed to integrate the algorithms, process PolSAR data, and image as well as visualize the ionospheric measurements. A number of tests have been conducted using ISSI with PolSAR data collected from various latitude regions using the phase array-type L-band synthetic aperture radar (PALSAR) onboard Japan Aerospace Exploration Agency's Advanced Land Observing Satellite mission, and also with Global Positioning System data. These tests have demonstrated and validated SAR-derived ionospheric images and data correction algorithms.

  1. SAR Tomography Based on Block Compressive Sensing

    Directory of Open Access Journals (Sweden)

    Wang Aichun

    2016-02-01

    Full Text Available While the use of SAR Tomography (TomoSAR based on Compressive Sensing (CS makes it possible to reconstruct the height profile of an observed scene, the performance of the reconstruction decreases for a structural observed scene. To deal with this issue, we propose using TomoSAR based on Block Compressive Sensing (BCS, which changes the reconstruction of the structural observed scene into a BCS problem under the principles of CS. Further, the block size is established by utilizing the relationship between the characteristics of the structural observed scene and the SAR parameters, such that the BCS problem is efficiently solved with a block sparse l1/l2 norm optimization signal model. Compared with existing CSTomoSAR methods, the proposed BCS-TomoSAR method makes better use of the sparsity and structure information of a structural observed scene, and has higher precision and better reconstruction performance. We used simulations and Radarsat-2 data to verify the effectiveness of this proposed method.

  2. Two Decades of Multi-Sensor Subsidence Monitoring over Ebro Delta Using Coherence-Based DInSAR Techniques

    Science.gov (United States)

    Pipia, Luca; Perez, Fernando; Marturia, Jordi; Corbera, Jordi; Jornet, Lluis; Rovira, Albert

    2016-08-01

    This work presents the historical study of the subsidence phenomenon over the Ebro Delta plain carried out as WPB6 in the frame of Ebro-ADMICLIM LIFE project, using coherence-based differential interferometric SAR techniques (DInSAR). To this end, the whole SAR archive available at ESA over the area of interest (AOI) at C-Band and L-Band has been analyzed. The results provided by each stack term of absolute deformation and deformation-rate maps are first shown. Then, a space-time filtering method to take advantage of the redundant information provided by ERS and ENVISAT data is put forward. C-band and L-band retrievals are then compared, and future monitoring activity based on Sentinel-1 imaging is discussed.

  3. UAVSAR: InSAR and PolSAR Test Bed for the Proposed NI-SAR Mission

    Science.gov (United States)

    Jones, C. E.; Hensley, S.; Lou, Y.

    2014-12-01

    UAVSAR, which first became operational in 2009, has served as an operational testbed for the NI-SAR L-band radar concept and a unique instrument in its own right. UAVSAR supports a broad array of basic and applied geoscience, covering on smaller scale all the disciplines NI-SAR would be able to address on a global scale. Although designed specifically to provide high accuracy repeated flight tracks and precise imaging geometry for InSAR-based solid earth studies, its fully polarimetric operation, low noise, and consistent calibration accuracy has made it a premier instrument for PolSAR-based studies also. Since 2009 it has successfully imaged more than 16 million km2 and >4300 quad-polarimetric data products are now publicly available online. Upgrades made in the last year to automate the repeat track processing serve as a model for generating large volumes of InSAR products: Since January 2014 more than 700 interferometric products have been released, exceeding the output of all previous years combined. Standardly available products now include browse images of all InSAR acquisitions and coregistered single-look complex image stacks suitable for standard time series analysis. Here we present an overview of the wide range of studies utilizing UAVSAR data including those based on polarimetry and pair-wise and times series interferometry, highlighting both the unique capabilities of UAVSAR and the ways in which NI-SAR would be able to dramatically extend the capabilities. This research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  4. Optimal Gaussian Filter for Effective Noise Filtering

    OpenAIRE

    Kopparapu, Sunil; Satish, M

    2014-01-01

    In this paper we show that the knowledge of noise statistics contaminating a signal can be effectively used to choose an optimal Gaussian filter to eliminate noise. Very specifically, we show that the additive white Gaussian noise (AWGN) contaminating a signal can be filtered best by using a Gaussian filter of specific characteristics. The design of the Gaussian filter bears relationship with the noise statistics and also some basic information about the signal. We first derive a relationship...

  5. Use of Radarsat-2 Polarimetric SAR Images for Fuel Moisture Mapping in Alaska Boreal Forests and South Africa Savannahs

    Science.gov (United States)

    Leblon, B.; Bourgeau-Chavez, L. L.; Kong, M.; Buckley, J. R.; Mathieu, R. M.; Charbonneau, F.; Gross, C. P.; Naidoo, L.

    2014-12-01

    The study reported a comparison between two Radarsat-2 polarimetric SAR (polSAR) images from extreme dry versus wet conditions are compared in an effort to determine the value of using polarimetric SAR data for estimating fuel moisture over South Africa savannahs and Alaska boreal forests. The savannahs study area is located into the Kruger National Park area and has 36 sites of lowveld savannas from bare overgrazed sites to medium-dense savannahs. The boreal forest study area has a chronosequence of black spruce ecosystems (recent burns, shrub-dominated regenerating forests , open canopied forests, moderately dense forest cover). Both study areas have a fairly level topography suitable for radar studies. The polSAR images were acquired using the same beam mode (FQ5 (23-25° incidence angle over the boreal sites, FQ15 (34.47-36.05° incidence angle) over the savannahs sites). Over each study area, soil moisture and vegetation structural data were measured in situ concurrently to the acquisition of the SAR imagery. The polSAR images were filtered for speckle noise using a Lee sigma filter and several polarimetric products were computed, such as those directly derived from the images (single linear and polairzed backscatters, polarimetric discriminators) and from target decompositions (Freeman-Durden, new van Zyl, Cloude-Pottier). Because most of these variables have a different unit, a normalized difference (in %) for each variable was calculated using the median values of the dry and wet dates for easier comparison of variable changes between the dates. Over both study areas, the normalized difference between wet and dry conditions was lower when higher tree canopy occurs. Results show utility of C-HH and C-RR polarized backscatters. Several polarimetric discriminators (dmin, Pr max, Pr min, Smax, Smin) were also significantly affected by the soil wetness. The Freeman Durden and van Zyl decomposition parameters outperformed the Cloude-Pottier decomposition

  6. Online Health Education on SARS to University Students during the SARS Outbreak

    Science.gov (United States)

    Wong, Mee Lian; Koh, David; Iyer, Prasad; Seow, Adeline; Goh, Lee Gan; Chia, Sin Eng; Lim, Meng Kin; Ng, Daniel; Ong, Choon Nam; Phua, Kai Hong; Tambyah, Paul; Chow, Vincent T K; Chew, Suok Kai; Chandran, Ravi; Lee, Hin Peng

    2005-01-01

    Little is known about how online learning may be used to disseminate health information rapidly and widely to large university populations if there is an infectious disease outbreak. During the SARS outbreak in Singapore in 2003, a six-lesson elearning module on SARS was developed for a large university population of 32,000 students. The module…

  7. Interdigital filter design

    CSIR Research Space (South Africa)

    Du Plessis, WP

    2009-10-01

    Full Text Available flexible, and allows design tradeoffs to be evaluated in an intuitive way. Keywords: Cavity resonator filters, microwave filters, coupled transmission lines. 1 Introduction Interdigital filters are popular at the higher microwave frequencies for a... number of reasons. Ideal interdigital filters have perfect symmetry which means that they have better phase and delay characteristics than combline filters [1]. The couplings between the resonators of interdigital filters are also lower than those...

  8. Satellite SAR interferometry for monitoring dam deformation in Portugal

    OpenAIRE

    Joaquim, Sousa; Lazecky, Milan; Hlavacova, Ivana; Bakon, Matus; Patrício, Glória

    2016-01-01

    The paper offers three examples of satellite SAR interferometry (InSAR) application for monitoring dam deformations: Paradela, Raiva and Alto Ceira, all of them in Portugal. Dam deformations were estimated using several sets of ERS and Envisat C-band SAR data by PS-InSAR method that offers accuracy of a millimeter per year at monitoring man-made tructures. The results show potential of InSAR but also summarize limits of C-band InSAR in these particular cases and can be handful to recogn...

  9. Human monoclonal antibody as prophylaxis for SARS coronavirus infection in ferrets

    NARCIS (Netherlands)

    ter Meulen, Jan; Bakker, Alexander B. H.; van den Brink, Edward N.; Weverling, Gerrit J.; Martina, Byron E. E.; Haagmans, Bart L.; Kuiken, Thijs; de Kruif, John; Preiser, Wolfgang; Spaan, Willy; Gelderblom, Hans R.; Goudsmit, Jaap; Osterhaus, Albert D. M. E.

    2004-01-01

    SARS coronavirus continues to cause sporadic cases of severe acute respiratory syndrome (SARS) in China. No active or passive immunoprophylaxis for disease induced by SARS coronavirus is available. We investigated prophylaxis of SARS coronavirus infection with a neutralising human monoclonal

  10. Investigation of ionospheric effects on SAR Interferometry (InSAR): A case study of Hong Kong

    Science.gov (United States)

    Zhu, Wu; Ding, Xiao-Li; Jung, Hyung-Sup; Zhang, Qin; Zhang, Bo-Chen; Qu, Wei

    2016-08-01

    Synthetic Aperture Radar Interferometry (InSAR) has demonstrated its potential for high-density spatial mapping of ground displacement associated with earthquakes, volcanoes, and other geologic processes. However, this technique may be affected by the ionosphere, which can result in the distortions of Synthetic Aperture Radar (SAR) images, phases, and polarization. Moreover, ionospheric effect has become and is becoming further significant with the increasing interest in low-frequency SAR systems, limiting the further development of InSAR technique. Although some research has been carried out, thorough analysis of ionospheric influence on true SAR imagery is still limited. Based on this background, this study performs a thorough investigation of ionospheric effect on InSAR through processing L-band ALOS-1/PALSAR-1 images and dual-frequency Global Positioning System (GPS) data over Hong Kong, where the phenomenon of ionospheric irregularities often occurs. The result shows that the small-scale ionospheric irregularities can cause the azimuth pixel shifts and phase advance errors on interferograms. Meanwhile, it is found that these two effects result in the stripe-shaped features in InSAR images. The direction of the stripe-shaped effects keep approximately constant in space for our InSAR dataset. Moreover, the GPS-derived rate of total electron content change index (ROTI), an index to reflect the level of ionospheric disturbances, may be a useful indicator for predicting the ionospheric effect for SAR images. This finding can help us evaluate the quality of SAR images when considering the ionospheric effect.

  11. An Efficient SAR Image Segmentation Framework Using Transformed Nonlocal Mean and Multi-Objective Clustering in Kernel Space

    Directory of Open Access Journals (Sweden)

    Dongdong Yang

    2015-02-01

    Full Text Available Synthetic aperture radar (SAR image segmentation usually involves two crucial issues: suitable speckle noise removing technique and effective image segmentation methodology. Here, an efficient SAR image segmentation method considering both of the two aspects is presented. As for the first issue, the famous nonlocal mean (NLM filter is introduced in this study to suppress the multiplicative speckle noise in SAR image. Furthermore, to achieve a higher denoising accuracy, the local neighboring pixels in the searching window are projected into a lower dimensional subspace by principal component analysis (PCA. Thus, the nonlocal mean filter is implemented in the subspace. Afterwards, a multi-objective clustering algorithm is proposed using the principals of artificial immune system (AIS and kernel-induced distance measures. The multi-objective clustering has been shown to discover the data distribution with different characteristics and the kernel methods can improve its robustness to noise and outliers. Experiments demonstrate that the proposed method is able to partition the SAR image robustly and accurately than the conventional approaches.

  12. Active Optical Lattice Filters

    Directory of Open Access Journals (Sweden)

    Gary Evans

    2005-06-01

    Full Text Available Optical lattice filter structures including gains are introduced and analyzed. The photonic realization of the active, adaptive lattice filter is described. The algorithms which map between gains space and filter coefficients space are presented and studied. The sensitivities of filter parameters with respect to gains are derived and calculated. An example which is relevant to adaptive signal processing is also provided.

  13. Completing the gaps in Kilauea's Father's Day InSAR displacement signature with ScanSAR

    Science.gov (United States)

    Bertran Ortiz, A.; Pepe, A.; Lanari, R.; Lundgren, P.; Rosen, P. A.

    2009-12-01

    Currently there are gaps in the known displacement signature obtained with InSAR at Kilauea between 2002 and 2009. InSAR data can be richer than GPS because of denser spatial cover. However, to better model rapidly varying and non-steady geophysical events InSAR is limited because of its less dense time observations of the area under study. The ScanSAR mode currently available in several satellites mitigates this effect because the satellite may illuminate a given area more than once within an orbit cycle. The Kilauea displacement graph below from Instituto per Il Rilevamento Electromagnetico dell'Ambiente (IREA) is a cut in space of the displacement signature obtained from a time series of several stripmap-to-stripmap interferograms. It shows that critical information is missing, especially between 2006 and 2007. The displacement is expected to be non-linear judging from the 2007-2008 displacement signature, thus simple interpolation would not suffice. The gap can be filled by incorporating Envisat stripmap-to-ScanSAR interferograms available during that time period. We propose leveraging JPL's new ROI-PAC ScanSAR module to create stripmap-to-ScanSAR interferograms. The new interferograms will be added to the stripmap ones in order to extend the existing stripmap time series generated by using the Small BAseline Subset (SBAS) technique. At AGU we will present denser graphs that better capture Kilauea's displacement between 2003 and 2009.

  14. Filter replacement lifetime prediction

    Science.gov (United States)

    Hamann, Hendrik F.; Klein, Levente I.; Manzer, Dennis G.; Marianno, Fernando J.

    2017-10-25

    Methods and systems for predicting a filter lifetime include building a filter effectiveness history based on contaminant sensor information associated with a filter; determining a rate of filter consumption with a processor based on the filter effectiveness history; and determining a remaining filter lifetime based on the determined rate of filter consumption. Methods and systems for increasing filter economy include measuring contaminants in an internal and an external environment; determining a cost of a corrosion rate increase if unfiltered external air intake is increased for cooling; determining a cost of increased air pressure to filter external air; and if the cost of filtering external air exceeds the cost of the corrosion rate increase, increasing an intake of unfiltered external air.

  15. Infrastructure monitoring with spaceborne SAR sensors

    CERN Document Server

    ANGHEL, ANDREI; CACOVEANU, REMUS

    2017-01-01

    This book presents a novel non-intrusive infrastructure monitoring technique based on the detection and tracking of scattering centers in spaceborne SAR images. The methodology essentially consists of refocusing each available SAR image on an imposed 3D point cloud associated to the envisaged infrastructure element and identifying the reliable scatterers to be monitored by means of four dimensional (4D) tomography. The methodology described in this book provides a new perspective on infrastructure monitoring with spaceborne SAR images, is based on a standalone processing chain, and brings innovative technical aspects relative to conventional approaches. The book is intended primarily for professionals and researchers working in the area of critical infrastructure monitoring by radar remote sensing.

  16. Verification of L-band SAR calibration

    Science.gov (United States)

    Larson, R. W.; Jackson, P. L.; Kasischke, E.

    1985-01-01

    Absolute calibration of a digital L-band SAR system to an accuracy of better than 3 dB has been verified. This was accomplished with a calibration signal generator that produces the phase history of a point target. This signal relates calibration values to various SAR data sets. Values of radar cross-section (RCS) of reference reflectors were obtained using a derived calibration relationship for the L-band channel on the ERIM/CCRS X-C-L SAR system. Calibrated RCS values were compared to known RCS values of each reference reflector for verification and to obtain an error estimate. The calibration was based on the radar response to 21 calibrated reference reflectors.

  17. Junction Point Detection Algorithm for SAR Image

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    2013-01-01

    Full Text Available In this paper, we propose a novel junction point detector based on an azimuth consensus for remote sensing images. To eliminate the impact of noise and some noncorrelated edges of SAR image, an azimuth consensus constraint is developed. In addition to detecting the locations of junctions at the subpixel level, this operator recognizes their structures as well. A new formula that includes a minimization criterion for the total weighted distance is proposed to compute the locations of junction points accurately. Compared with other well-known detectors, including Forstner, JUDOCA, and CPDA, the experimental results indicate that our operator outperforms them both in location accuracy of junction points and in angle accuracy of branch edges. Moreover, our method possesses satisfying robustness to the impact of noise and changes of the SAR images. Our operator can be potentially used to solve a number of problems in computer vision, such as SAR image registration, wide-baseline matching, and UAV navigation system.

  18. Compact L-band SAR payload for UAV

    OpenAIRE

    Zaragoza Arbo, Josep

    2016-01-01

    Design and development of a Compact L-band SAR payload for UAV Design of a signal interference canceller due to the coupling between antennas for a SAR system. Diseño de un cancelador de señal interferente debido al acoplamiento entre antenas para un sistema SAR. Disseny d'un cancel·lador de senyal interferent degut a l'acoblament entre antenes per un sistema SAR.

  19. Fusion of synthetic aperture radiometer and noise waveform SAR images

    OpenAIRE

    Lukin, Konstantin A.; Kudriashov, V. V.

    2014-01-01

    Noise waveform SAR generates 2D SAR images of a scene. Advanced radiometric SAR imaging provides information on the objects thermal radiation, angular coordinates and even range. The brightness temperatures of rough and smooth surfaces are different. An active, noise waveform, operating mode of bistatic radiometer, based on antennae with beam synthesis, is considered with respect to the roughness criteria. The optimal and quasi-optimal algorithms for fusion of radiometric and SAR images are p...

  20. Potential and limitations of high resolution multitemporal sar images in river morphology

    Science.gov (United States)

    Mitidieri, Francesco; Nicolina Papa, Maria; Amitrano, Donato; Ruello, Giuseppe

    2017-04-01

    In this study we test the capability of satellite synthetic aperture radar (SAR) images to enrich the monitoring of river geomorphological processes. A case study on the Italian River Orco is presented; a set of 100 COSMO-SkyMed stripmap images (from October 2008 to December 2016) from Italian Space Agency was employed. All the data, acquired with medium look angle (almost 30°) and HH polarization for increasing the land-water contrast, were processed in order to calibrate, register and reduce the speckle effect. Moreover, the optimal weighting multi-temporal De Grandi filter was adopted to allow an effective extraction of the water surfaces contour. This method was applied to extract water contours over the entire historical series of SAR datasets available. Thanks to the generated information we were able to monitor the lateral dynamic of the water channels and infer on the relations between low or peak flow and river morphology. Multi-temporal SAR images were compared to orthophotos and in situ measurements (performed at the same time of a SAR acquisition) in terms of river features extraction (e.g. active channel, vegetated islands) and measurements of morphometric parameters (e.g. reach length, channel width, curvature and sinuosity). Results of this comparison highlighted the potential offered by the use of SAR technology, with some limitations. In particular, good performances were reached by the extraction of the active channel and vegetated island compared to the ones obtained using the orthophotos. On the other hand, some issues were encountered in extracting water surfaces where riffles exhibit surface waves having heights greater than the wavelength of the electromagnetic signal of SAR, which causes a low land-water contrast. Hence, given the high spatial (3 m) and temporal resolution (15 days) of SAR images and the all-weather all-time acquisition conditions, a significant enhancement in the river management capabilities is possible, in particular

  1. The Recent Severe Acute Respiratory Syndrome (SARS) Epidemic ...

    African Journals Online (AJOL)

    The symptoms of SARS are quite similar to those of common cold, malaria and respiratory tract infections all of which are common in our environment. SARS, being a new disease, has as yet neither a definite diagnostic test nor treatment. With the international transmission of SARS first reported in March 2003, it became ...

  2. (Q)SARs for human toxicological endpoints: a literature search

    NARCIS (Netherlands)

    Hulzebos E; Schielen P; Masilankiewicz L; CSR; NVIC

    1999-01-01

    The goal here was to describe human toxicological SARs (structure-activity relationships) available in the literature and used by the US EPA (Environmental Protection Agency). The CSR laboratory investigated implementation of SARs for the effect assessment. SARs correlate the molecular structure

  3. (Q)SARs for human toxicological endpoints: a literature search

    NARCIS (Netherlands)

    Hulzebos E; Schielen P; Masilankiewicz L; CSR; NVIC

    1999-01-01

    Het doel van dit rapport is het beschrijven van humaan toxicologische SARs (structuur-activiteitsrelaties) die beschikbaar zijn in de literatuur alsmede de SARs die gebruikt worden door de US EPA (Environmental Protection Agency). De implementatie van het gebruik van SARs voor de effect assessment

  4. Which preventive measures might protect health care workers from SARS?

    Directory of Open Access Journals (Sweden)

    Huang Jian

    2009-03-01

    Full Text Available Abstract Background Despite the use of a series of preventive measures, a high incidence of severe acute respiratory syndrome (SARS was observed among health care workers (HCWs during the SARS epidemic. This study aimed to determine which preventive measures may have been effective in protecting HCWs from infection, and which were not effective. Methods A retrospective study was performed among 758 'frontline' health care workers who cared for SARS patients at the Second Affiliated Hospital and the Third Affiliated Hospital of Sun Yat-sen University. The HCWs with IgG against SARS and those without IgG against SARS were respectively defined as the "case group" and the "control group", and logistic regression was conducted to explore the risk factors for SARS infection in HCWs. Results After adjusting for age, gender, marital status, educational level, professional title, and the department in which an individual worked, the results of a multivariate logistic regression analysis indicated that incidence of SARS among HCWs was significantly and positively associated with: performing tracheal intubations for SARS patients, methods used for air ventilation in wards, avoiding face-to-face interaction with SARS patients, the number of pairs of gloves worn by HCWs, and caring for serious SARS cases. Conclusion Some measures, particularly good air ventilation in SARS wards, may be effective in minimizing or preventing SARS transmission among HCWs in hospitals.

  5. SAR clutter simulation with terrain effects

    Science.gov (United States)

    Greig, David W.; Scott, Iain

    2002-02-01

    A model for the signal returns from terrain features for a Synthetic Aperture Radar is developed. A standard range-azimuth geometry is used to divide the surface area into cells for which clutter returns are generated. This geometry is extended to a spherical Earth to introduce effects due to varying terrain height and slope, and to determine areas of shadow. The calculation of phase variation in the returned pulses at the IQ level required to successfully form a SAR is discussed. The technique is illustrated with an example which demonstrates the effect of look angle on SAR images.

  6. Geocoding of AIRSAR/TOPSAR SAR Data

    Science.gov (United States)

    Holecz, Francesco; Lou, Yun-Ling; vanZyl, Jakob

    1996-01-01

    It has been demonstrated and recognized that radar interferometry is a promising method for the determination of digital elevation information and terrain slope from Synthetic Aperture Radar (SAR) data. An important application of Interferometric SAR (InSAR) data in areas with topographic variations is that the derived elevation and slope can be directly used for the absolute radiometric calibration of the amplitude SAR data as well as for scattering mechanisms analysis. On the other hand polarimetric SAR data has long been recognized as permitting a more complete inference of natural surfaces than a single channel radar system. In fact, imaging polarimetry provides the measurement of the amplitude and relative phase of all transmit and receive polarizations. On board the NASA DC-8 aircraft, NASA/JPL operates the multifrequency (P, L and C bands) multipolarimetric radar AIRSAR. The TOPSAR, a special mode of the AIRSAR system, is able to collect single-pass interferometric C- and/or L-band VV polarized data. A possible configuration of the AIRSAR/TOPSAR system is to acquire single-pass interferometric data at C-band VV polarization and polarimetric radar data at the two other lower frequencies. The advantage of this system configuration is to get digital topography information at the same time the radar data is collected. The digital elevation information can therefore be used to correctly calibrate the SAR data. This step is directly included in the new AIRSAR Integrated Processor. This processor uses a modification of the full motion compensation algorithm described by Madsen et al. (1993). However, the Digital Elevation Model (DEM) with the additional products such as local incidence angle map, and the SAR data are in a geometry which is not convenient, since especially DEMs must be referred to a specific cartographic reference system. Furthermore, geocoding of SAR data is important for multisensor and/or multitemporal purposes. In this paper, a procedure to

  7. Automatic Transfer of SAR Patterns for AUXSAR

    Science.gov (United States)

    2015-10-01

    RB M RB S)− - , - − CG HC-130J, MH-65, MH-60T (PFPS) − CG GCCS .ovl for Mission Suite/Pallet (HU-144/130J) − Cutter VEGA (ECS/ECDIS) − Garmin Flight...rom • GoogleEarth /eGIS .kml (pattern name) ( S CG Ai f )• .xml PFP : Large rcra t • .fpl ( Garmin Flight Plan: G1000 etc) • .txt (ForeFlight) • .sar...Transfer of SAR Patterns for AUXSAR| RDC Mr. Sean Lester | CG-761| Oct 2015 17 AUXSAR Field Test– Garmin GPSmap 496 In Flight 7/8/2016

  8. Science data collection with polarimetric SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Woelders, Kim; Madsen, Søren Nørvang

    1996-01-01

    Discusses examples on the use of polarimetric SAR in a number of Earth science studies. The studies are presently being conducted by the Danish Center for Remote Sensing. A few studies of the European Space Agency's EMAC programme are also discussed. The Earth science objectives are presented......, and the potential of polarimetric SAR is discussed and illustrated with data collected by the Danish airborne EMISAR system during a number of experiments in 1994 and 1995. The presentation will include samples of data acquired for the different studies...

  9. Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis

    NARCIS (Netherlands)

    Hamming, [No Value; Timens, W; Bulthuis, MLC; Lely, AT; Navis, GJ; van Goor, H

    Severe acute respiratory syndrome (SARS) is an acute infectious disease that spreads mainly via the respiratory route. A distinct coronavirus (SARS-CoV) has been identified as the aetiological agent of SARS. Recently, a metallopeptidase named angiotensin-converting enzyme 2 (ACE2) has been

  10. SARS knowledge, perceptions, and behaviors: a comparison between Finns and the Dutch during the SARS outbreak in 2003

    NARCIS (Netherlands)

    Vartti, A.M.; Oenema, A.; Schreck, M.; Uutela, A.; Zwart, de O.; Brug, J.; Aro, A.R.

    2009-01-01

    BACKGROUND: The SARS outbreak served to test both local and international outbreak management and risk communication practices. PURPOSE: The study compares SARS knowledge, perceptions, behaviors, and information between Finns and the Dutch during the SARS outbreak in 2003. METHOD: The participants

  11. Calibration Results for J-ERS-1 SAR Data Produced by the Alaska SAR Facility

    Science.gov (United States)

    Freeman, A.; Alves, M.; Williams, J.

    1993-01-01

    The Alaska SAR Facility has been receiving and processing SAR data from the J-ERS-1 satellite since Spring 1992. Corner reflectors have been set up for J-ERS-1 SAR calibration at a site near Delta Junction, in central Alaska. Image quality and calibration analysis results from the Delta Junction site and others will be presented in this paper. The impact of the 3-bit Analog-to-Digital Converter and the automatic stepping of the gain as a function of range in the J-ERS-1 radar receiver on calibration performance has been assessed. Preliminary observations on J-ERS-1 SAR data are that the average Signal-to-Noise ratio is generally fairly low, in the range 5-6 dB. Azimuth ambiguity levels are higher than preflight analysis indicated. Over land, the dynamic range in the backscatter at L-band for approximately 36 degree incidence angle is often fairly high...

  12. Quantum-SAR Extension of the Spectral-SAR Algorithm. Application to Polyphenolic Anticancer Bioactivity

    Directory of Open Access Journals (Sweden)

    Adrian Chiriac

    2009-03-01

    Full Text Available Aiming to assess the role of individual molecular structures in the molecular mechanism of ligand-receptor interaction correlation analysis, the recent Spectral-SAR approach is employed to introduce the Quantum-SAR (QuaSAR “wave” and “conversion factor” in terms of difference between inter-endpoint inter-molecular activities for a given set of compounds; this may account for inter-conversion (metabolization of molecular (concentration effects while indicating the structural (quantum based influential/detrimental role on bio-/eco- effect in a causal manner rather than by simple inspection of measured values; the introduced QuaSAR method is then illustrated for a study of the activity of a series of flavonoids on breast cancer resistance protein.

  13. TomoSAR Platform: The New Irstea Service as Demand for SAR, Interferometry, Polarimetry and Tomography

    Science.gov (United States)

    Ho Tong Minh, Dinh; Ngo, Yen-Nhi; Baghdadi, Nicolas; Maurel, Pierre

    2016-08-01

    Developing and improving methods to monitor both natural and non-natural environments such as forest and urban in space and time is a timely challenge. To overcome this challenge, we created a software platform - TomoSAR. The kernel of this platform supports the entire processing from SAR, Interferometry, Polarimetry, to Tomography (so called TomoSAR). The objective of this paper is to introduce this platform about its design architecture and its capacity. We showed four examples to highlight the TomoSAR platform capacities. First, the useful of the interferometric coherence of TOPS Sentinel-1 for land cover classification was highlighted. Second, a TOPS Sentinel-1 differential interferogram in a complex scenario volcano was successfully produced. Third, a TOPS Persistent Scatterers Interferometry analysis for estimating subsidence in Ho Chi Minh City area was demonstrated. Finally, the capability of processing and modelling of 3D P-band tomography in volume forest scattering were reported.

  14. Sensory Pollution from Bag Filters, Carbon Filters and Combinations

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Clausen, Geo; Weschler, Charles J.

    2008-01-01

    by an upstream pre-filter (changed monthly), an EU7 filter protected by an upstream activated carbon (AC) filter, and EU7 filters with an AC filter either downstream or both upstream and downstream. In addition, two types of stand-alone combination filters were evaluated: a bag-type fiberglass filter...

  15. Epidemic Models for SARS and Measles

    Science.gov (United States)

    Rozema, Edward

    2007-01-01

    Recent events have led to an increased interest in emerging infectious diseases. This article applies various deterministic models to the SARS epidemic of 2003 and a measles outbreak in the Netherlands in 1999-2000. We take a historical approach beginning with the well-known logistic curve and a lesser-known extension popularized by Pearl and Reed…

  16. What is Gammarus campylops of Sars, 1894

    NARCIS (Netherlands)

    Stock, J.H.; Kant, P.

    1966-01-01

    A revision of the specimens described by Sars, 1894, as Gammarus campylops Leach, 1814, proved that they did not belong to that species, nor to Gammarus ochlos Reid, 1945 (= G. sarsi Reid, 1943), as Reid believed. Reid’s species, of which also original specimens have been reexamined, is identical

  17. SAR-sensing of vegetation wetness

    NARCIS (Netherlands)

    de Jong, JJM; Klaassen, W

    1998-01-01

    The goal of this study is to measure rain induced forest canopy wetness. The approach used is ERS tandem mission C-band SAR backscatter change detection between successive dry and rainy days. The observed backscatter change is positively related with modelled canopy wetness change. It is therefore

  18. Abundant SAR11 viruses in the ocean.

    Science.gov (United States)

    Zhao, Yanlin; Temperton, Ben; Thrash, J Cameron; Schwalbach, Michael S; Vergin, Kevin L; Landry, Zachary C; Ellisman, Mark; Deerinck, Tom; Sullivan, Matthew B; Giovannoni, Stephen J

    2013-02-21

    Several reports proposed that the extraordinary dominance of the SAR11 bacterial clade in ocean ecosystems could be a consequence of unusual mechanisms of resistance to bacteriophage infection, including 'cryptic escape' through reduced cell size and/or K-strategist defence specialism. Alternatively, the evolution of high surface-to-volume ratios coupled with minimal genomes containing high-affinity transporters enables unusually efficient metabolism for oxidizing dissolved organic matter in the world's oceans that could support vast population sizes despite phage susceptibility. These ideas are important for understanding plankton ecology because they emphasize the potentially important role of top-down mechanisms in predation, thus determining the size of SAR11 populations and their concomitant role in biogeochemical cycling. Here we report the isolation of diverse SAR11 viruses belonging to two virus families in culture, for which we propose the name 'pelagiphage', after their host. Notably, the pelagiphage genomes were highly represented in marine viral metagenomes, demonstrating their importance in nature. One of the new phages, HTVC010P, represents a new podovirus subfamily more abundant than any seen previously, in all data sets tested, and may represent one of the most abundant virus subfamilies in the biosphere. This discovery disproves the theory that SAR11 cells are immune to viral predation and is consistent with the interpretation that the success of this highly abundant microbial clade is the result of successfully evolved adaptation to resource competition.

  19. Matrix approach to modelling of SAR signals

    NARCIS (Netherlands)

    Lidicky, L.; Hoogeboom, P.

    2005-01-01

    The paper presents a matrix approach to implementation of SAR signal generating and processing schemes. This approach is advantageous when matrix oriented software such as Matlab is used. Algorithms written in this type of software packages run faster compared to the same algorithms written for the

  20. Peptide Mimicrying Between SARS Coronavirus Spike Protein and Human Proteins Reacts with SARS Patient Serum

    Directory of Open Access Journals (Sweden)

    K.-Y. Hwa

    2008-01-01

    Full Text Available Molecular mimicry, defined as similar structures shared by molecules from dissimilar genes or proteins, is a general strategy used by pathogens to infect host cells. Severe acute respiratory syndrome (SARS is a new human respiratory infectious disease caused by SARS coronavirus (SARS-CoV. The spike (S protein of SARS-CoV plays an important role in the virus entry into a cell. In this study, eleven synthetic peptides from the S protein were selected based on its sequence homology with human proteins. Two of the peptides D07 (residues 927–937 and D08 (residues 942–951 were recognized by the sera of SARS patients. Murine hyperimmune sera against these peptides bound to proteins of human lung epithelial cells A549. Another peptide D10 (residues 490–502 stimulated A549 to proliferate and secrete IL-8. The present results suggest that the selected S protein regions, which share sequence homology with human proteins, may play important roles in SARS-CoV infection.

  1. Citizens’ Health Information Behaviors During SARS Spread Periods in Taiwan

    Directory of Open Access Journals (Sweden)

    Nei-Ching Yeh

    2003-09-01

    Full Text Available The purpose of this study is to investigate the information behaviors of citizens during the periods of SARS spreading in Taiwan. This study is exploratory in nature, and the naturalistic inquiry approach was applied. Sixteen persons, aged from 20 to 62 years old, were interviewed in order to understand their primary information channels of obtaining SARS information, the characteristics of information communication, the methods of infection, the attitudes toward SARS news, and the influences of SARS to life. The findings show that most participants obtained SARS information from televisions. SARS became the major topic of chatting between people, but telephone communication replaced face to face communication. Part of interviewers applied folk medicine to guard against SARS. Participant dissatisfied that governments did not announce much more authoritative information. The results also found participants’ information sharing and information avoidance behaviors.[Article content in Chinese

  2. SAR Raw Data Generation for Complex Airport Scenes

    Directory of Open Access Journals (Sweden)

    Jia Li

    2014-10-01

    Full Text Available The method of generating the SAR raw data of complex airport scenes is studied in this paper. A formulation of the SAR raw signal model of airport scenes is given. Via generating the echoes from the background, aircrafts and buildings, respectively, the SAR raw data of the unified SAR imaging geometry is obtained from their vector additions. The multipath scattering and the shadowing between the background and different ground covers of standing airplanes and buildings are analyzed. Based on the scattering characteristics, coupling scattering models and SAR raw data models of different targets are given, respectively. A procedure is given to generate the SAR raw data of airport scenes. The SAR images from the simulated raw data demonstrate the validity of the proposed method.

  3. USING MULTI RESOLUTION CENSUS AND RANKLET TRANSFORMATION IN LONG BASE LINE SAR IMAGE MATCHING

    Directory of Open Access Journals (Sweden)

    M. A. Ghannadi

    2013-09-01

    Full Text Available Stereo radargrammetry is a mature technique for deriving height information from SAR image pairs. Generally height derived method by Radargrammetry consists of two stages: Images matching and space intersection. In this paper we propose a multi-step image matching algorithm founded on feature based matching. In this multi step algorithm, a SAR image is firstly filtered by a speckle suppression algorithm. a SIFT (Scale invariant feature transform is used to extract feature points. Then we use non parametric Transformation as discriptor for the points extracted. Matching is sometimes more efficient when operating on image signals that have been transformed in some way, rather than operating on the pure intensity values themselves; In this article we use a pair of spotlight long base line TerraSAR-X images from JAM (IRAN. In a part with 700 × 700 pixels of these images 90 points are matched with using Ranklet algorithm. The mean absolute error of the corresponding points is 0.9 pixel. This match points number is 49 points with using multi resolution Census. The result shows that our proposed multi step image matching is superior to the Most FBM methods in terms of accuracy and number of matched points.

  4. Onboard Interferometric SAR Processor for the Ka-Band Radar Interferometer (KaRIn)

    Science.gov (United States)

    Esteban-Fernandez, Daniel; Rodriquez, Ernesto; Peral, Eva; Clark, Duane I.; Wu, Xiaoqing

    2011-01-01

    An interferometric synthetic aperture radar (SAR) onboard processor concept and algorithm has been developed for the Ka-band radar interferometer (KaRIn) instrument on the Surface and Ocean Topography (SWOT) mission. This is a mission- critical subsystem that will perform interferometric SAR processing and multi-look averaging over the oceans to decrease the data rate by three orders of magnitude, and therefore enable the downlink of the radar data to the ground. The onboard processor performs demodulation, range compression, coregistration, and re-sampling, and forms nine azimuth squinted beams. For each of them, an interferogram is generated, including common-band spectral filtering to improve correlation, followed by averaging to the final 1 1-km ground resolution pixel. The onboard processor has been prototyped on a custom FPGA-based cPCI board, which will be part of the radar s digital subsystem. The level of complexity of this technology, dictated by the implementation of interferometric SAR processing at high resolution, the extremely tight level of accuracy required, and its implementation on FPGAs are unprecedented at the time of this reporting for an onboard processor for flight applications.

  5. Hyper-Temporal C-Band SAR for Baseline Woody Structural Assessments in Deciduous Savannas

    Directory of Open Access Journals (Sweden)

    Russell Main

    2016-08-01

    Full Text Available Savanna ecosystems and their woody vegetation provide valuable resources and ecosystem services. Locally calibrated and cost effective estimates of these resources are required in order to satisfy commitments to monitor and manage change within them. Baseline maps of woody resources are important for analyzing change over time. Freely available, and highly repetitive, C-band data has the potential to be a viable alternative to high-resolution commercial SAR imagery (e.g., RADARSAT-2, ALOS2 in generating large-scale woody resources maps. Using airborne LiDAR as calibration, we investigated the relationships between hyper-temporal C-band ASAR data and woody structural parameters, namely total canopy cover (TCC and total canopy volume (TCV, in a deciduous savanna environment. Results showed that: the temporal filter reduced image variance; the random forest model out-performed the linear model; while the TCV metric consistently showed marginally higher accuracies than the TCC metric. Combinations of between 6 and 10 images could produce results comparable to high resolution commercial (C- & L-band SAR imagery. The approach showed promise for producing a regional scale, locally calibrated, baseline maps for the management of deciduous savanna resources, and lay a foundation for monitoring using time series of data from newer C-band SAR sensors (e.g., Sentinel1.

  6. In Defense of Filtering.

    Science.gov (United States)

    Burt, David

    1997-01-01

    Presents responses to 10 common arguments against the use of Internet filters in libraries. Highlights include keyword blocking; selection of materials; liability of libraries using filters; users' judgments; Constitutional issues, including First Amendment rights; and censorship. (LRW)

  7. HEPA filter monitoring program

    Science.gov (United States)

    Kirchner, K. N.; Johnson, C. M.; Aiken, W. F.; Lucerna, J. J.; Barnett, R. L.; Jensen, R. T.

    1986-07-01

    The testing and replacement of HEPA filters, widely used in the nuclear industry to purify process air, are costly and labor-intensive. Current methods of testing filter performance, such as differential pressure measurement and scanning air monitoring, allow determination of overall filter performance but preclude detection of incipient filter failure such as small holes in the filters. Using current technology, a continual in-situ monitoring system was designed which provides three major improvements over current methods of filter testing and replacement. The improvements include: cost savings by reducing the number of intact filters which are currently being replaced unnecessarily; more accurate and quantitative measurement of filter performance; and reduced personnel exposure to a radioactive environment by automatically performing most testing operations.

  8. Novel Backup Filter Device for Candle Filters

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, B.; Goldsmith, R.; Dunham, G.; Henderson, A.

    2002-09-18

    The currently preferred means of particulate removal from process or combustion gas generated by advanced coal-based power production processes is filtration with candle filters. However, candle filters have not shown the requisite reliability to be commercially viable for hot gas clean up for either integrated gasifier combined cycle (IGCC) or pressurized fluid bed combustion (PFBC) processes. Even a single candle failure can lead to unacceptable ash breakthrough, which can result in (a) damage to highly sensitive and expensive downstream equipment, (b) unacceptably low system on-stream factor, and (c) unplanned outages. The U.S. Department of Energy (DOE) has recognized the need to have fail-safe devices installed within or downstream from candle filters. In addition to CeraMem, DOE has contracted with Siemens-Westinghouse, the Energy & Environmental Research Center (EERC) at the University of North Dakota, and the Southern Research Institute (SRI) to develop novel fail-safe devices. Siemens-Westinghouse is evaluating honeycomb-based filter devices on the clean-side of the candle filter that can operate up to 870 C. The EERC is developing a highly porous ceramic disk with a sticky yet temperature-stable coating that will trap dust in the event of filter failure. SRI is developing the Full-Flow Mechanical Safeguard Device that provides a positive seal for the candle filter. Operation of the SRI device is triggered by the higher-than-normal gas flow from a broken candle. The CeraMem approach is similar to that of Siemens-Westinghouse and involves the development of honeycomb-based filters that operate on the clean-side of a candle filter. The overall objective of this project is to fabricate and test silicon carbide-based honeycomb failsafe filters for protection of downstream equipment in advanced coal conversion processes. The fail-safe filter, installed directly downstream of a candle filter, should have the capability for stopping essentially all particulate

  9. MST Filterability Tests

    Energy Technology Data Exchange (ETDEWEB)

    Poirier, M. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Burket, P. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Duignan, M. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-03-12

    The Savannah River Site (SRS) is currently treating radioactive liquid waste with the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Extraction Unit (MCU). The low filter flux through the ARP has limited the rate at which radioactive liquid waste can be treated. Recent filter flux has averaged approximately 5 gallons per minute (gpm). Salt Batch 6 has had a lower processing rate and required frequent filter cleaning. Savannah River Remediation (SRR) has a desire to understand the causes of the low filter flux and to increase ARP/MCU throughput. In addition, at the time the testing started, SRR was assessing the impact of replacing the 0.1 micron filter with a 0.5 micron filter. This report describes testing of MST filterability to investigate the impact of filter pore size and MST particle size on filter flux and testing of filter enhancers to attempt to increase filter flux. The authors constructed a laboratory-scale crossflow filter apparatus with two crossflow filters operating in parallel. One filter was a 0.1 micron Mott sintered SS filter and the other was a 0.5 micron Mott sintered SS filter. The authors also constructed a dead-end filtration apparatus to conduct screening tests with potential filter aids and body feeds, referred to as filter enhancers. The original baseline for ARP was 5.6 M sodium salt solution with a free hydroxide concentration of approximately 1.7 M.3 ARP has been operating with a sodium concentration of approximately 6.4 M and a free hydroxide concentration of approximately 2.5 M. SRNL conducted tests varying the concentration of sodium and free hydroxide to determine whether those changes had a significant effect on filter flux. The feed slurries for the MST filterability tests were composed of simple salts (NaOH, NaNO2, and NaNO3) and MST (0.2 – 4.8 g/L). The feed slurry for the filter enhancer tests contained simulated salt batch 6 supernate, MST, and filter enhancers.

  10. Estimation of glacier surface motion by robust phase correlation and point like features of SAR intensity images

    Science.gov (United States)

    Fang, Li; Xu, Yusheng; Yao, Wei; Stilla, Uwe

    2016-11-01

    For monitoring of glacier surface motion in pole and alpine areas, radar remote sensing is becoming a popular technology accounting for its specific advantages of being independent of weather conditions and sunlight. In this paper we propose a method for glacier surface motion monitoring using phase correlation (PC) based on point-like features (PLF). We carry out experiments using repeat-pass TerraSAR X-band (TSX) and Sentinel-1 C-band (S1C) intensity images of the Taku glacier in Juneau icefield located in southeast Alaska. The intensity imagery is first filtered by an improved adaptive refined Lee filter while the effect of topographic reliefs is removed via SRTM-X DEM. Then, a robust phase correlation algorithm based on singular value decomposition (SVD) and an improved random sample consensus (RANSAC) algorithm is applied to sequential PLF pairs generated by correlation using a 2D sinc function template. The approaches for glacier monitoring are validated by both simulated SAR data and real SAR data from two satellites. The results obtained from these three test datasets confirm the superiority of the proposed approach compared to standard correlation-like methods. By the use of the proposed adaptive refined Lee filter, we achieve a good balance between the suppression of noise and the preservation of local image textures. The presented phase correlation algorithm shows the accuracy of better than 0.25 pixels, when conducting matching tests using simulated SAR intensity images with strong noise. Quantitative 3D motions and velocities of the investigated Taku glacier during a repeat-pass period are obtained, which allows a comprehensive and reliable analysis for the investigation of large-scale glacier surface dynamics.

  11. Oriented Fiber Filter Media

    OpenAIRE

    R. Bharadwaj; A. Patel, S. Chokdeepanich, Ph.D.; G.G. Chase, Ph.D.

    2008-01-01

    Coalescing filters are widely used throughout industry and improved performance will reduce droplet emissions and operating costs. Experimental observations show orientation of micro fibers in filter media effect the permeability and the separation efficiency of the filter media. In this work two methods are used to align the fibers to alter the filter structure. The results show that axially aligned fiber media improve quality factor on the order of 20% and cutting media on an angle from a t...

  12. Filter service system

    Science.gov (United States)

    Sellers, Cheryl L [Peoria, IL; Nordyke, Daniel S [Arlington Heights, IL; Crandell, Richard A [Morton, IL; Tomlins, Gregory [Peoria, IL; Fei, Dong [Peoria, IL; Panov, Alexander [Dunlap, IL; Lane, William H [Chillicothe, IL; Habeger, Craig F [Chillicothe, IL

    2008-12-09

    According to an exemplary embodiment of the present disclosure, a system for removing matter from a filtering device includes a gas pressurization assembly. An element of the assembly is removably attachable to a first orifice of the filtering device. The system also includes a vacuum source fluidly connected to a second orifice of the filtering device.

  13. Bias aware Kalman filters

    DEFF Research Database (Denmark)

    Drecourt, J.-P.; Madsen, H.; Rosbjerg, Dan

    2006-01-01

    This paper reviews two different approaches that have been proposed to tackle the problems of model bias with the Kalman filter: the use of a colored noise model and the implementation of a separate bias filter. Both filters are implemented with and without feedback of the bias into the model sta...

  14. HEPA filter encapsulation

    Science.gov (United States)

    Gates-Anderson, Dianne D.; Kidd, Scott D.; Bowers, John S.; Attebery, Ronald W.

    2003-01-01

    A low viscosity resin is delivered into a spent HEPA filter or other waste. The resin is introduced into the filter or other waste using a vacuum to assist in the mass transfer of the resin through the filter media or other waste.

  15. An improved PolSAR image speckle reduction algorithm based on LMMSE and RICA

    Science.gov (United States)

    Jiang, Chang; He, Xiufeng

    2017-07-01

    Although the linear minimum mean square error (LMMSE) filter removes speckle in polarimetric synthetic aperture radar (PolSAR) images, it has the disadvantage of losing edge detail. In this paper, we propose a new filter based on robust independent component analysis (RICA) and LMMSE. This approach describes edge features in a span image by selecting the adaptive direction window and calculating the edge weight value of the spatial domain, and improves the objective function by using a step polynomial to extract the estimate of the source image with minimum noise. This technique preserves not only the edge information in the images, but also the polarimetric information. Experiments were conducted on the NASA/JPL AIRSAR L-band of the San Francisco area, and evaluated by means of the speckle reduction index and the edge preservation index. The experimental results show that the proposed method effectively reduces speckle, retains edges, and preserves the polarimetric scattering mechanisms.

  16. LARGE OIL SPILL CLASSIFICATION USING SAR IMAGES BASED ON SPATIAL HISTOGRAM

    Directory of Open Access Journals (Sweden)

    I. Schvartzman

    2016-06-01

    Full Text Available Among the different types of marine pollution, oil spill is a major threat to the sea ecosystems. Remote sensing is used in oil spill response. Synthetic Aperture Radar (SAR is an active microwave sensor that operates under all weather conditions and provides information about the surface roughness and covers large areas at a high spatial resolution. SAR is widely used to identify and track pollutants in the sea, which may be due to a secondary effect of a large natural disaster or by a man-made one . The detection of oil spill in SAR imagery relies on the decrease of the backscattering from the sea surface, due to the increased viscosity, resulting in a dark formation that contrasts with the brightness of the surrounding area. Most of the use of SAR images for oil spill detection is done by visual interpretation. Trained interpreters scan the image, and mark areas of low backscatter and where shape is a-symmetrical. It is very difficult to apply this method for a wide area. In contrast to visual interpretation, automatic detection algorithms were suggested and are mainly based on scanning dark formations, extracting features, and applying big data analysis. We propose a new algorithm that applies a nonlinear spatial filter that detects dark formations and is not susceptible to noises, such as internal or speckle. The advantages of this algorithm are both in run time and the results retrieved. The algorithm was tested in genesimulations as well as on COSMO-SkyMed images, detecting the Deep Horizon oil spill in the Gulf of Mexico (occurred on 20/4/2010. The simulation results show that even in a noisy environment, oil spill is detected. Applying the algorithm to the Deep Horizon oil spill, the algorithm classified the oil spill better than focusing on dark formation algorithm. Furthermore, the results were validated by the National Oceanic and Atmospheric Administration (NOAA data.

  17. Large Oil Spill Classification Using SAR Images Based on Spatial Histogram

    Science.gov (United States)

    Schvartzman, I.; Havivi, S.; Maman, S.; Rotman, S. R.; Blumberg, D. G.

    2016-06-01

    Among the different types of marine pollution, oil spill is a major threat to the sea ecosystems. Remote sensing is used in oil spill response. Synthetic Aperture Radar (SAR) is an active microwave sensor that operates under all weather conditions and provides information about the surface roughness and covers large areas at a high spatial resolution. SAR is widely used to identify and track pollutants in the sea, which may be due to a secondary effect of a large natural disaster or by a man-made one . The detection of oil spill in SAR imagery relies on the decrease of the backscattering from the sea surface, due to the increased viscosity, resulting in a dark formation that contrasts with the brightness of the surrounding area. Most of the use of SAR images for oil spill detection is done by visual interpretation. Trained interpreters scan the image, and mark areas of low backscatter and where shape is a-symmetrical. It is very difficult to apply this method for a wide area. In contrast to visual interpretation, automatic detection algorithms were suggested and are mainly based on scanning dark formations, extracting features, and applying big data analysis. We propose a new algorithm that applies a nonlinear spatial filter that detects dark formations and is not susceptible to noises, such as internal or speckle. The advantages of this algorithm are both in run time and the results retrieved. The algorithm was tested in genesimulations as well as on COSMO-SkyMed images, detecting the Deep Horizon oil spill in the Gulf of Mexico (occurred on 20/4/2010). The simulation results show that even in a noisy environment, oil spill is detected. Applying the algorithm to the Deep Horizon oil spill, the algorithm classified the oil spill better than focusing on dark formation algorithm. Furthermore, the results were validated by the National Oceanic and Atmospheric Administration (NOAA) data.

  18. Statistical Analysis of SAR Sea Clutter for Classification Purposes

    Directory of Open Access Journals (Sweden)

    Jaime Martín-de-Nicolás

    2014-09-01

    Full Text Available Statistical analysis of radar clutter has always been one of the topics, where more effort has been put in the last few decades. These studies were usually focused on finding the statistical models that better fitted the clutter distribution; however, the goal of this work is not the modeling of the clutter, but the study of the suitability of the statistical parameters to carry out a sea state classification. In order to achieve this objective and provide some relevance to this study, an important set of maritime and coastal Synthetic Aperture Radar data is considered. Due to the nature of the acquisition of data by SAR sensors, speckle noise is inherent to these data, and a specific study of how this noise affects the clutter distribution is also performed in this work. In pursuit of a sense of wholeness, a thorough study of the most suitable statistical parameters, as well as the most adequate classifier is carried out, achieving excellent results in terms of classification success rates. These concluding results confirm that a sea state classification is not only viable, but also successful using statistical parameters different from those of the best modeling distribution and applying a speckle filter, which allows a better characterization of the parameters used to distinguish between different sea states.

  19. Regenerative particulate filter development

    Science.gov (United States)

    Descamp, V. A.; Boex, M. W.; Hussey, M. W.; Larson, T. P.

    1972-01-01

    Development, design, and fabrication of a prototype filter regeneration unit for regenerating clean fluid particle filter elements by using a backflush/jet impingement technique are reported. Development tests were also conducted on a vortex particle separator designed for use in zero gravity environment. A maintainable filter was designed, fabricated and tested that allows filter element replacement without any leakage or spillage of system fluid. Also described are spacecraft fluid system design and filter maintenance techniques with respect to inflight maintenance for the space shuttle and space station.

  20. Federated query services provided by the Seamless SAR Archive project

    Science.gov (United States)

    Baker, S.; Bryson, G.; Buechler, B.; Meertens, C. M.; Crosby, C. J.; Fielding, E. J.; Nicoll, J.; Youn, C.; Baru, C.

    2013-12-01

    The NASA Advancing Collaborative Connections for Earth System Science (ACCESS) seamless synthetic aperture radar (SAR) archive (SSARA) project is a 2-year collaboration between UNAVCO, the Alaska Satellite Facility (ASF), the Jet Propulsion Laboratory (JPL), and OpenTopography at the San Diego Supercomputer Center (SDSC) to design and implement a seamless distributed access system for SAR data and derived data products (i.e. interferograms). A major milestone for the first year of the SSARA project was a unified application programming interface (API) for SAR data search and results at ASF and UNAVCO (WInSAR and EarthScope data archives) through the use of simple web services. A federated query service was developed using the unified APIs, providing users a single search interface for both archives (http://www.unavco.org/ws/brokered/ssara/sar/search). A command line client that utilizes this new service is provided as an open source utility for the community on GitHub (https://github.com/bakerunavco/SSARA). Further API development and enhancements added more InSAR specific keywords and quality control parameters (Doppler centroid, faraday rotation, InSAR stack size, and perpendicular baselines). To facilitate InSAR processing, the federated query service incorporated URLs for DEM (from OpenTopography) and tropospheric corrections (from the JPL OSCAR service) in addition to the URLs for SAR data. This federated query service will provide relevant QC metadata for selecting pairs of SAR data for InSAR processing and all the URLs necessary for interferogram generation. Interest from the international community has prompted an effort to incorporate other SAR data archives (the ESA Virtual Archive 4 and the DLR TerraSAR-X_SSC Geohazard Supersites and Natural Laboratories collections) into the federated query service which provide data for researchers outside the US and North America.

  1. Mutational dynamics of the SARS coronavirus in cell culture and human populations isolated in 2003

    Directory of Open Access Journals (Sweden)

    Ooi Eng

    2004-09-01

    Full Text Available Abstract Background The SARS coronavirus is the etiologic agent for the epidemic of the Severe Acute Respiratory Syndrome. The recent emergence of this new pathogen, the careful tracing of its transmission patterns, and the ability to propagate in culture allows the exploration of the mutational dynamics of the SARS-CoV in human populations. Methods We sequenced complete SARS-CoV genomes taken from primary human tissues (SIN3408, SIN3725V, SIN3765V, cultured isolates (SIN848, SIN846, SIN842, SIN845, SIN847, SIN849, SIN850, SIN852, SIN3408L, and five consecutive Vero cell passages (SIN2774_P1, SIN2774_P2, SIN2774_P3, SIN2774_P4, SIN2774_P5 arising from SIN2774 isolate. These represented individual patient samples, serial in vitro passages in cell culture, and paired human and cell culture isolates. Employing a refined mutation filtering scheme and constant mutation rate model, the mutation rates were estimated and the possible date of emergence was calculated. Phylogenetic analysis was used to uncover molecular relationships between the isolates. Results Close examination of whole genome sequence of 54 SARS-CoV isolates identified before 14th October 2003, including 22 from patients in Singapore, revealed the mutations engendered during human-to-Vero and Vero-to-human transmission as well as in multiple Vero cell passages in order to refine our analysis of human-to-human transmission. Though co-infection by different quasipecies in individual tissue samples is observed, the in vitro mutation rate of the SARS-CoV in Vero cell passage is negligible. The in vivo mutation rate, however, is consistent with estimates of other RNA viruses at approximately 5.7 × 10-6 nucleotide substitutions per site per day (0.17 mutations per genome per day, or two mutations per human passage (adjusted R-square = 0.4014. Using the immediate Hotel M contact isolates as roots, we observed that the SARS epidemic has generated four major genetic groups that are

  2. EXTRACTION OF COASTLINES WITH FUZZY APPROACH USING SENTINEL-1 SAR IMAGE

    Directory of Open Access Journals (Sweden)

    N. Demir

    2016-06-01

    Full Text Available Coastlines are important features for water resources, sea products, energy resources etc. Coastlines are changed dynamically, thus automated methods are necessary for analysing and detecting the changes along the coastlines. In this study, Sentinel-1 C band SAR image has been used to extract the coastline with fuzzy logic approach. The used SAR image has VH polarisation and 10x10m. spatial resolution, covers 57 sqkm area from the south-east of Puerto-Rico. Additionally, radiometric calibration is applied to reduce atmospheric and orbit error, and speckle filter is used to reduce the noise. Then the image is terrain-corrected using SRTM digital surface model. Classification of SAR image is a challenging task since SAR and optical sensors have very different properties. Even between different bands of the SAR sensors, the images look very different. So, the classification of SAR image is difficult with the traditional unsupervised methods. In this study, a fuzzy approach has been applied to distinguish the coastal pixels than the land surface pixels. The standard deviation and the mean, median values are calculated to use as parameters in fuzzy approach. The Mean-standard-deviation (MS Large membership function is used because the large amounts of land and ocean pixels dominate the SAR image with large mean and standard deviation values. The pixel values are multiplied with 1000 to easify the calculations. The mean is calculated as 23 and the standard deviation is calculated as 12 for the whole image. The multiplier parameters are selected as a: 0.58, b: 0.05 to maximize the land surface membership. The result is evaluated using airborne LIDAR data, only for the areas where LIDAR dataset is available and secondly manually digitized coastline. The laser points which are below 0,5 m are classified as the ocean points. The 3D alpha-shapes algorithm is used to detect the coastline points from LIDAR data. Minimum distances are calculated between the

  3. Ceramic fiber filter technology

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, B.L.; Janney, M.A.

    1996-06-01

    Fibrous filters have been used for centuries to protect individuals from dust, disease, smoke, and other gases or particulates. In the 1970s and 1980s ceramic filters were developed for filtration of hot exhaust gases from diesel engines. Tubular, or candle, filters have been made to remove particles from gases in pressurized fluidized-bed combustion and gasification-combined-cycle power plants. Very efficient filtration is necessary in power plants to protect the turbine blades. The limited lifespan of ceramic candle filters has been a major obstacle in their development. The present work is focused on forming fibrous ceramic filters using a papermaking technique. These filters are highly porous and therefore very lightweight. The papermaking process consists of filtering a slurry of ceramic fibers through a steel screen to form paper. Papermaking and the selection of materials will be discussed, as well as preliminary results describing the geometry of papers and relative strengths.

  4. The flight test of Pi-SAR(L) for the repeat-pass interferometric SAR

    Science.gov (United States)

    Nohmi, Hitoshi; Shimada, Masanobu; Miyawaki, Masanori

    2006-09-01

    This paper describes the experiment of the repeat pass interferometric SAR using Pi-SAR(L). The air-borne repeat-pass interferometric SAR is expected as an effective method to detect landslide or predict a volcano eruption. To obtain a high-quality interferometric image, it is necessary to make two flights on the same flight pass. In addition, since the antenna of the Pi-SAR(L) is secured to the aircraft, it is necessary to fly at the same drift angle to keep the observation direction same. We built a flight control system using an auto pilot which has been installed in the airplane. This navigation system measures position and altitude precisely with using a differential GPS, and the PC Navigator outputs a difference from the desired course to the auto pilot. Since the air density is thinner and the speed is higher than the landing situation, the gain of the control system is required to be adjusted during the repeat pass flight. The observation direction could be controlled to some extent by adjusting a drift angle with using a flight speed control. The repeat-pass flight was conducted in Japan for three days in late November. The flight was stable and the deviation was within a few meters for both horizontal and vertical direction even in the gusty condition. The SAR data were processed in time domain based on range Doppler algorism to make the complete motion compensation. Thus, the interferometric image processed after precise phase compensation is shown.

  5. PolInSAR tomography for vertical profile retrieval of forest vegetation using spaceborne SAR data

    Science.gov (United States)

    Joshi, Sushil K.; Kumar, Shashi; Agrawal, Shefali; Dinh, Ho T. M.

    2016-05-01

    Forest height plays a crucial role to investigate the bio-physical parameters of forest and the terrestrial carbon. PolInSAR based inversion modeling has been successfully implemented on airborne and space-borne SAR data. SAR tomography, which is an extension of cross-track interferometric processing is a recent approach to separate scatterers in cross range direction, thus generates its vertical profile. This study highlighted the potential of tomographic processing of fully polarimetric Radarsat-2 SAR system to retrieve backscatter power at different height levels. Teak forest in Haldwani forest division of Uttarakhand state of India was chosen as the test site. Since SAR tomography is a spectral estimation problem, Fourier transform and beamforming based spectral estimations were applied on the dataset to obtain their vertical profiles. Fourier severely suffered from high side lobes which was drastically reduced by implementing beam-forming by taking into account the multi-looking effect at the expense of radiometric accuracy. Backscattered power values were found to be different at different height levels of the forest vegetation. Vertical profile for Fourier as well as beam-forming were also retrieved.

  6. SARS: Safeguards Accounting and Reporting Software

    Science.gov (United States)

    Mohammedi, B.; Saadi, S.; Ait-Mohamed, S.

    In order to satisfy the requirements of the SSAC (State System for Accounting and Control of nuclear materials), for recording and reporting objectives; this computer program comes to bridge the gape between nuclear facilities operators and national inspection verifying records and delivering reports. The SARS maintains and generates at-facility safeguards accounting records and generates International Atomic Energy Agency (IAEA) safeguards reports based on accounting data input by the user at any nuclear facility. A database structure is built and BORLAND DELPHI programming language has been used. The software is designed to be user-friendly, to make extensive and flexible management of menus and graphs. SARS functions include basic physical inventory tacking, transaction histories and reporting. Access controls are made by different passwords.

  7. Estimating the Doppler centroid of SAR data

    DEFF Research Database (Denmark)

    Madsen, Søren Nørvang

    1989-01-01

    After reviewing frequency-domain techniques for estimating the Doppler centroid of synthetic-aperture radar (SAR) data, the author describes a time-domain method and highlights its advantages. In particular, a nonlinear time-domain algorithm called the sign-Doppler estimator (SDE) is shown to have...... attractive properties. An evaluation based on an existing SEASAT processor is reported. The time-domain algorithms are shown to be extremely efficient with respect to requirements on calculations and memory, and hence they are well suited to real-time systems where the Doppler estimation is based on raw SAR...... data. For offline processors where the Doppler estimation is performed on processed data, which removes the problem of partial coverage of bright targets, the ΔE estimator and the CDE (correlation Doppler estimator) algorithm give similar performance. However, for nonhomogeneous scenes it is found...

  8. SAR observations in the Gulf of Mexico

    Science.gov (United States)

    Sheres, David

    1992-01-01

    The Gulf of Mexico (GOM) exhibits a wealth of energetic ocean features; they include the Loop Current with velocities of about 2 m/s and strong shear fronts, mesoscale eddies, double vortices, internal waves, and the outflow of the 'Mighty Mississippi' river. These energetic features can have a strong impact on the economies of the states surrounding the Gulf. Large fisheries, oil and gas production as well as pollution transport are relevant issues. These circulation features in the Gulf are invisible to conventional IR and visible satellite imagery during the Summer months due to cloud cover and uniform surface temperatures. Synthetic Aperture Radar (SAR) imagery of the Gulf does penetrate the cloud cover and shows a rich assembly of features there year-round. Below are preliminary results from GOM SAR imagery taken by SEASAT in 1978 and by the AIRSAR program in 1991.

  9. Compact planar microwave blocking filters

    Science.gov (United States)

    U-Yen, Kongpop (Inventor); Wollack, Edward J. (Inventor)

    2012-01-01

    A compact planar microwave blocking filter includes a dielectric substrate and a plurality of filter unit elements disposed on the substrate. The filter unit elements are interconnected in a symmetrical series cascade with filter unit elements being organized in the series based on physical size. In the filter, a first filter unit element of the plurality of filter unit elements includes a low impedance open-ended line configured to reduce the shunt capacitance of the filter.

  10. COMPARISON OF C-BAND AND X-BAND POLARIMETRIC SAR DATA FOR RIVER ICE CLASSIFICATION ON THE PEACE RIVER

    Directory of Open Access Journals (Sweden)

    H. Łoś

    2016-06-01

    Full Text Available In this study, synthetic aperture radar (SAR data from TerraSAR-X were compared with RADARSAT-2 data to evaluate their effectiveness for river ice monitoring on the Peace River. For several years RADARSAT-2 data have been successfully used for river ice observation. However, it is important to take into account data from other satellites as they may provide solutions when it is not possible to obtain images from the preferred system (e.g., in the case of acquisition priority conflicts. In this study we compared three TerraSAR-X (X-band and three RADARSAT-2 (C-band datasets acquired in December 2013 on a section of the Peace River, Canada. For selected classes (open water, skim ice, juxtaposed skim ice, agglomerated skim ice, frazil run and consolidated ice we compared backscattering values in HH and VV polarisation and performed Wishart supervised classification. Covariance matrices that were previously filtered using a refined Lee filter were used as input data for classification. For all data sets the overall accuracy was higher than 80%. Similar errors associated with classification output were observed for data from both satellite systems.

  11. SAR Product Improvements and Enhancements - SARprises

    Science.gov (United States)

    2013-09-30

    paper on current fields at Orkney, Scotland, was accepted for publication in IEEE - TGARS and is currently in press (available on IEEE Xplore as Early...Sea surface velocity vector retrieval using dual-beam interferometry: First demonstration, IEEE TGARS, 43, 2494- 2502, 2005. [2] Chapron, B., F...Bight by airborne along-track interferometric SAR, Proc. IGARSS 2002, 1822-1824, IEEE , 2002. [4] Bjerklie, D.M., S.L. Dingman, C.J. Vorosmarty, C.H

  12. SAR Polarimetric Scattering from Natural Terrains

    Science.gov (United States)

    2017-02-17

    calculate the polarimetric speckle statistics (amplitude and phase difference), followed by a comparison with theoretical distributions . For fully developed...AFRL-AFOSR-JP-TR-2017-0013 SAR Polarimetric Scattering from Natural Terrains Kun-Shan Chen National Central University Final Report 02/17/2017... DISTRIBUTION A: Distribution approved for public release. AF Office Of Scientific Research (AFOSR)/ IOA Arlington, Virginia 22203 Air Force Research

  13. SARS: Down But Still a Threat

    Science.gov (United States)

    2003-08-01

    Diphtheria Tickborne Encephalitis E. coli 0157:H7 Avian Influenza SARS Nipah virus Japanese Encephalitis Hendra virus Lyssavirus Ross River Fever virus ...pandemic. When a new type of flu virus emerges from a reassortment of animal and human viruses to which humans have no prior immunity, a pandemic...utilized the World Health Organization’s (WHO) global network of research facilities to share data and speed the identification of the virus causing

  14. Cross-calibration of interferometric SAR data

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2003-01-01

    Generation of digital elevation models from interferometric synthetic aperture radar (SAR) data is a well established technique. Achieving a high geometric fidelity calls for a calibration accounting for inaccurate navigation data and system parameters as well as system imperfections. Fully...... automated calibration techniques are preferable, especially for operational mapping. The author presents one such technique, called cross-calibration. Though developed for single-pass interferometry, it may be applicable to multi-pass interferometry, too. Cross-calibration requires stability during mapping...

  15. A 3-D SAR approach to IFSAR processing

    Energy Technology Data Exchange (ETDEWEB)

    DOERRY,ARMIN W.; BICKEL,DOUGLAS L.

    2000-03-01

    Interferometric SAR (IFSAR) can be shown to be a special case of 3-D SAR image formation. In fact, traditional IFSAR processing results in the equivalent of merely a super-resolved, under-sampled, 3-D SAR image. However, when approached as a 3-D SAR problem, a number of IFSAR properties and anomalies are easily explained. For example, IFSAR decorrelation with height is merely ordinary migration in 3-D SAR. Consequently, treating IFSAR as a 3-D SAR problem allows insight and development of proper motion compensation techniques and image formation operations to facilitate optimal height estimation. Furthermore, multiple antenna phase centers and baselines are easily incorporated into this formulation, providing essentially a sparse array in the elevation dimension. This paper shows the Polar Format image formation algorithm extended to 3 dimensions, and then proceeds to apply it to the IFSAR collection geometry. This suggests a more optimal reordering of the traditional IFSAR processing steps.

  16. Low-SAR metamaterial-inspired printed monopole antenna

    Science.gov (United States)

    Hossain, M. I.; Faruque, M. R. I.; Islam, M. T.; Ali, M. T.

    2017-01-01

    In this paper, a low-SAR metamaterial-embedded planar monopole antenna is introduced for a wireless communication system. A printed monopole antenna is designed for modern mobile, which operates in GSM, UMTS, LTE, WLAN, and Bluetooth frequency bands. A metamaterial structure is designed to use in the mobile handset with a multi-band printed monopole antenna. The finite integration technique of the CST microwave studio is used in this study. The measurement of antenna performances is taken in an anechoic chamber, and the SAR values are measured using COMOSAR system. The results indicate that metamaterial structure leads to reduce SAR without affecting antenna performance significantly. According to the measured results, the metamaterial attachment leads to reduce 87.7% peak SAR, 68.2% 1-g SAR, and 46.78% 10-g SAR compared to antenna without metamaterial.

  17. The diffuse ensemble filter

    Directory of Open Access Journals (Sweden)

    X. Yang

    2009-07-01

    Full Text Available A new class of ensemble filters, called the Diffuse Ensemble Filter (DEnF, is proposed in this paper. The DEnF assumes that the forecast errors orthogonal to the first guess ensemble are uncorrelated with the latter ensemble and have infinite variance. The assumption of infinite variance corresponds to the limit of "complete lack of knowledge" and differs dramatically from the implicit assumption made in most other ensemble filters, which is that the forecast errors orthogonal to the first guess ensemble have vanishing errors. The DEnF is independent of the detailed covariances assumed in the space orthogonal to the ensemble space, and reduces to conventional ensemble square root filters when the number of ensembles exceeds the model dimension. The DEnF is well defined only in data rich regimes and involves the inversion of relatively large matrices, although this barrier might be circumvented by variational methods. Two algorithms for solving the DEnF, namely the Diffuse Ensemble Kalman Filter (DEnKF and the Diffuse Ensemble Transform Kalman Filter (DETKF, are proposed and found to give comparable results. These filters generally converge to the traditional EnKF and ETKF, respectively, when the ensemble size exceeds the model dimension. Numerical experiments demonstrate that the DEnF eliminates filter collapse, which occurs in ensemble Kalman filters for small ensemble sizes. Also, the use of the DEnF to initialize a conventional square root filter dramatically accelerates the spin-up time for convergence. However, in a perfect model scenario, the DEnF produces larger errors than ensemble square root filters that have covariance localization and inflation. For imperfect forecast models, the DEnF produces smaller errors than the ensemble square root filter with inflation. These experiments suggest that the DEnF has some advantages relative to the ensemble square root filters in the regime of small ensemble size, imperfect model, and copious

  18. Stochastic Approach in Wet Snow Detection Using Multitemporal SAR Data

    OpenAIRE

    Besic, Nikola; Vasile, Gabriel; Dedieu, Jean-Pierre; Chanussot, Jocelyn; Stankovic, Srdjan

    2015-01-01

    International audience; This paper introduces an alternative strategy for wet snow detection using multitemporal SAR data. The proposed change detection method is primarily based on the comparison between two X band SAR images acquired during the accumulation (winter) and the melting (spring) seasons, in the French Alps. The new decision criterion relies on the local intensity statistics of the SAR images by considering the backscattering ratio as a stochastic process: the probability that "t...

  19. SAR11 bacteria linked to ocean anoxia and nitrogen loss

    DEFF Research Database (Denmark)

    Tsementzi, Despina; Wu, Jieying; Deutsch, Samuel

    2016-01-01

    Bacteria of the SAR11 clade constitute up to one half of all microbial cells in the oxygen-rich surface ocean. SAR11 bacteria are also abundant in oxygen minimum zones (OMZs), where oxygen falls below detection and anaerobic microbes have vital roles in converting bioavailable nitrogen to N2 gas...... activity. These results link SAR11 to pathways of ocean nitrogen loss, redefining the ecological niche of Earth’s most abundant organismal group....

  20. Monitoring Building Deformation with InSAR: Experiments and Validation.

    Science.gov (United States)

    Yang, Kui; Yan, Li; Huang, Guoman; Chen, Chu; Wu, Zhengpeng

    2016-12-20

    Synthetic Aperture Radar Interferometry (InSAR) techniques are increasingly applied for monitoring land subsidence. The advantages of InSAR include high accuracy and the ability to cover large areas; nevertheless, research validating the use of InSAR on building deformation is limited. In this paper, we test the monitoring capability of the InSAR in experiments using two landmark buildings; the Bohai Building and the China Theater, located in Tianjin, China. They were selected as real examples to compare InSAR and leveling approaches for building deformation. Ten TerraSAR-X images spanning half a year were used in Permanent Scatterer InSAR processing. These extracted InSAR results were processed considering the diversity in both direction and spatial distribution, and were compared with true leveling values in both Ordinary Least Squares (OLS) regression and measurement of error analyses. The detailed experimental results for the Bohai Building and the China Theater showed a high correlation between InSAR results and the leveling values. At the same time, the two Root Mean Square Error (RMSE) indexes had values of approximately 1 mm. These analyses show that a millimeter level of accuracy can be achieved by means of InSAR technique when measuring building deformation. We discuss the differences in accuracy between OLS regression and measurement of error analyses, and compare the accuracy index of leveling in order to propose InSAR accuracy levels appropriate for monitoring buildings deformation. After assessing the advantages and limitations of InSAR techniques in monitoring buildings, further applications are evaluated.

  1. Forming rotated SAR images by real-time motion compensation.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2012-12-01

    Proper waveform parameter selection allows collecting Synthetic Aperture Radar (SAR) phase history data on a rotated grid in the Fourier Space of the scene being imaged. Subsequent image formation preserves the rotated geometry to allow SAR images to be formed at arbitrary rotation angles without the use of computationally expensive interpolation or resampling operations. This should be useful where control of image orientation is desired such as generating squinted stripmaps and VideoSAR applications, among others.

  2. InSAR Scientific Computing Environment

    Science.gov (United States)

    Gurrola, E. M.; Rosen, P. A.; Sacco, G.; Zebker, H. A.; Simons, M.; Sandwell, D. T.

    2010-12-01

    The InSAR Scientific Computing Environment (ISCE) is a software development effort in its second year within the NASA Advanced Information Systems and Technology program. The ISCE will provide a new computing environment for geodetic image processing for InSAR sensors that will enable scientists to reduce measurements directly from radar satellites and aircraft to new geophysical products without first requiring them to develop detailed expertise in radar processing methods. The environment can serve as the core of a centralized processing center to bring Level-0 raw radar data up to Level-3 data products, but is adaptable to alternative processing approaches for science users interested in new and different ways to exploit mission data. The NRC Decadal Survey-recommended DESDynI mission will deliver data of unprecedented quantity and quality, making possible global-scale studies in climate research, natural hazards, and Earth's ecosystem. The InSAR Scientific Computing Environment is planned to become a key element in processing DESDynI data into higher level data products and it is expected to enable a new class of analyses that take greater advantage of the long time and large spatial scales of these new data, than current approaches. At the core of ISCE is both legacy processing software from the JPL/Caltech ROI_PAC repeat-pass interferometry package as well as a new InSAR processing package containing more efficient and more accurate processing algorithms being developed at Stanford for this project that is based on experience gained in developing processors for missions such as SRTM and UAVSAR. Around the core InSAR processing programs we are building object-oriented wrappers to enable their incorporation into a more modern, flexible, extensible software package that is informed by modern programming methods, including rigorous componentization of processing codes, abstraction and generalization of data models, and a robust, intuitive user interface with

  3. Generic Kalman Filter Software

    Science.gov (United States)

    Lisano, Michael E., II; Crues, Edwin Z.

    2005-01-01

    The Generic Kalman Filter (GKF) software provides a standard basis for the development of application-specific Kalman-filter programs. Historically, Kalman filters have been implemented by customized programs that must be written, coded, and debugged anew for each unique application, then tested and tuned with simulated or actual measurement data. Total development times for typical Kalman-filter application programs have ranged from months to weeks. The GKF software can simplify the development process and reduce the development time by eliminating the need to re-create the fundamental implementation of the Kalman filter for each new application. The GKF software is written in the ANSI C programming language. It contains a generic Kalman-filter-development directory that, in turn, contains a code for a generic Kalman filter function; more specifically, it contains a generically designed and generically coded implementation of linear, linearized, and extended Kalman filtering algorithms, including algorithms for state- and covariance-update and -propagation functions. The mathematical theory that underlies the algorithms is well known and has been reported extensively in the open technical literature. Also contained in the directory are a header file that defines generic Kalman-filter data structures and prototype functions and template versions of application-specific subfunction and calling navigation/estimation routine code and headers. Once the user has provided a calling routine and the required application-specific subfunctions, the application-specific Kalman-filter software can be compiled and executed immediately. During execution, the generic Kalman-filter function is called from a higher-level navigation or estimation routine that preprocesses measurement data and post-processes output data. The generic Kalman-filter function uses the aforementioned data structures and five implementation- specific subfunctions, which have been developed by the user on

  4. Bistatic SAR: State of the Art and Development Trend

    Directory of Open Access Journals (Sweden)

    Zeng Tao

    2012-12-01

    Full Text Available Bistatic SAR (BiSAR systems have attracted the interests from global researchers and become a hotspot in the international radar community due to the progress of radar technology and rapidly increased applications nowadays. Based on the BiSAR experiments and breakthrough of the key technology, the paper summarized the general progresses of BiSAR systems, especially in European radar community, from different aspects such as system design, processing idea and topology etc. Different bistatic image formation algorithms have been analyzed and reviewed. Finally, the development trend is discussed in the paper.

  5. Rough Set Based Classification rules generation for SARS Patients.

    Science.gov (United States)

    Honghai, Feng; Guoshun, Chen; Yufeng, Wang; Bingru, Yang; Yumei, Chen

    2005-01-01

    SARS is an acute infectious disease and can cause a large amount of death. Up until now we have not known it well. With the experimental results of micronutrients of 30 SARS patients and 30 non-SARS patients, using rough set theory we induce some classification rules. Attribute reduction results show that micronutrients Fe, Ca, K and Na are necessary and sufficient for classification, whereas micronutrients Zn, Cu and Mg are not necessary or are redundant. Additionally, we find that micronutrient Ca has a strong correlation to SARS. The classification results of 30 other examples show that the rough set classification method is available.

  6. Evaluation of the Wishart test statistics for polarimetric SAR data

    DEFF Research Database (Denmark)

    Skriver, Henning; Nielsen, Allan Aasbjerg; Conradsen, Knut

    2003-01-01

    A test statistic for equality of two covariance matrices following the complex Wishart distribution has previously been used in new algorithms for change detection, edge detection and segmentation in polarimetric SAR images. Previously, the results for change detection and edge detection have been...... quantitatively evaluated. This paper deals with the evaluation of segmentation. A segmentation performance measure originally developed for single-channel SAR images has been extended to polarimetric SAR images, and used to evaluate segmentation for a merge-using-moment algorithm for polarimetric SAR data....

  7. Anti-SARS coronavirus agents: a patent review (2008 - present).

    Science.gov (United States)

    Kumar, Vathan; Jung, Young-Sik; Liang, Po-Huang

    2013-10-01

    A novel coronavirus (CoV), unlike previous typical human coronaviruses (HCoVs), was identified as causative agent for severe acute respiratory syndrome (SARS). SARS first surfaced as a pandemic in late 2002 and originated in southern China. SARS-CoV rapidly spread to > 30 countries by 2003, infecting nearly 8,000 people and causing around 800 fatalities. After 10 years of silence, a 2012 report alarmed researchers about the emergence of a new strain of CoV causing SARS-like disease. To combat SARS, scientists applied for patents on various therapeutic agents, including small-molecule inhibitors targeting the essential proteases, helicase and other proteins of the virus, natural products, approved drugs, molecules binding to the virus, neutralizing antibodies, vaccines, anti-sense RNA, siRNA and ribozyme against SARS-CoV. In this article, the patents published from 2008 to the present for the new therapeutics that could potentially be used in the prophylaxis and treatment of SARS are reviewed. The therapeutic interventions or prophylaxis discussed in this review seems to offer promising solutions to tackle SARS. Rather than being complacent about the results, we should envisage how to transform them into drug candidates that may be useful in combating SARS and related viral infections in the future.

  8. Observation Properties Analysis of Geo-SAR with Attitude Steering

    Directory of Open Access Journals (Sweden)

    Tian Yu-run

    2014-02-01

    Full Text Available Attitude Steering has been widely applied to the current low orbit SAR system to decrease the rang/azimuth coupling of the received data. This paper focuses on the impacts of attitude steering to the observation properties of Geo-SAR, namely, Doppler parameters, range swath, and rang cell migration effect, and a comparisonbetween 3 different ways of attitude steering is made. Based on the simulation results, the necessity of attitude steering for Geo-SAR is validated, and for Geo-SAR on elliptical orbit, 2D attitude steering is the most effective.

  9. SAR Subsets for Selected Field Sites, 2007-2010

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides Synthetic Aperture Radar (SAR) images for 42 selected sites from various terrestrial ecology and meteorological monitoring networks including...

  10. SAR Subsets for Selected Field Sites, 2007-2010

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides Synthetic Aperture Radar (SAR) images for 42 selected sites from various terrestrial ecology and meteorological monitoring networks...

  11. Spot- Zombie Filtering System

    OpenAIRE

    Arathy Rajagopal; B. Geethanjali; Arulprakash P

    2015-01-01

    A major security challenge on the Internet is the existence of the large number of compromised machines. Such machines have been increasingly used to launch various security attacks including spamming and spreading malware, DDoS, and identity theft. These compromised machines are called "Zombies". In general E-mail applications and providers uses spam filters to filter the spam messages. Spam filtering is a technique for discriminating the genuine message from the spam messages. The attackers...

  12. Hybrid Filter Membrane

    Science.gov (United States)

    Laicer, Castro; Rasimick, Brian; Green, Zachary

    2012-01-01

    Cabin environmental control is an important issue for a successful Moon mission. Due to the unique environment of the Moon, lunar dust control is one of the main problems that significantly diminishes the air quality inside spacecraft cabins. Therefore, this innovation was motivated by NASA s need to minimize the negative health impact that air-suspended lunar dust particles have on astronauts in spacecraft cabins. It is based on fabrication of a hybrid filter comprising nanofiber nonwoven layers coated on porous polymer membranes with uniform cylindrical pores. This design results in a high-efficiency gas particulate filter with low pressure drop and the ability to be easily regenerated to restore filtration performance. A hybrid filter was developed consisting of a porous membrane with uniform, micron-sized, cylindrical pore channels coated with a thin nanofiber layer. Compared to conventional filter media such as a high-efficiency particulate air (HEPA) filter, this filter is designed to provide high particle efficiency, low pressure drop, and the ability to be regenerated. These membranes have well-defined micron-sized pores and can be used independently as air filters with discreet particle size cut-off, or coated with nanofiber layers for filtration of ultrafine nanoscale particles. The filter consists of a thin design intended to facilitate filter regeneration by localized air pulsing. The two main features of this invention are the concept of combining a micro-engineered straight-pore membrane with nanofibers. The micro-engineered straight pore membrane can be prepared with extremely high precision. Because the resulting membrane pores are straight and not tortuous like those found in conventional filters, the pressure drop across the filter is significantly reduced. The nanofiber layer is applied as a very thin coating to enhance filtration efficiency for fine nanoscale particles. Additionally, the thin nanofiber coating is designed to promote capture of

  13. Fundamentals of Stochastic Filtering

    CERN Document Server

    Crisan, Dan

    2008-01-01

    The objective of stochastic filtering is to determine the best estimate for the state of a stochastic dynamical system from partial observations. The solution of this problem in the linear case is the well known Kalman-Bucy filter which has found widespread practical application. The purpose of this book is to provide a rigorous mathematical treatment of the non-linear stochastic filtering problem using modern methods. Particular emphasis is placed on the theoretical analysis of numerical methods for the solution of the filtering problem via particle methods. The book should provide sufficient

  14. Stripe delay filters

    OpenAIRE

    Zakharov, Alexander V.; Ilchenko, Mykhailo Ye.; Trubarov, Igor V.; Pinchuk, Ludmila S.

    2016-01-01

    There are considered constructions of microsized stripe delay filters, which are realized on a basis of ceramic materials with high dielectric permittivity. Delay time of non-minimal phase filters is 7–12 ns at frequencies of 1900 MHz with relative bandwidth of 3.6–3.85%. Filters dimensions are comparable with ones used in portable communication devices. Dimensions of researched three-resonator filter at frequency of 1900 MHz are 8.4×5×2 mm with material dielectric permittivity εr = 92, and 5...

  15. Nanofiber Filters Eliminate Contaminants

    Science.gov (United States)

    2009-01-01

    With support from Phase I and II SBIR funding from Johnson Space Center, Argonide Corporation of Sanford, Florida tested and developed its proprietary nanofiber water filter media. Capable of removing more than 99.99 percent of dangerous particles like bacteria, viruses, and parasites, the media was incorporated into the company's commercial NanoCeram water filter, an inductee into the Space Foundation's Space Technology Hall of Fame. In addition to its drinking water filters, Argonide now produces large-scale nanofiber filters used as part of the reverse osmosis process for industrial water purification.

  16. Analysis of summer subsidence in Barrow, Alaska, using InSAR and hyperspectral remote sensing

    OpenAIRE

    Mahmud Haghshenas Haghighi; M. Motagh; B. Heim; S. Chabrillat; D. Streletskiy; G. Grosse; T. Sachs; Katrin Kohnert

    2016-01-01

    In this study, gradual elevation change due to summer thawing of active layer in tundra permafrost landscape of Barrow, Alaska is investigated using SAR interferometry (InSAR) technique. We used a variety of SAR sensors including TerraSAR-X, ALOS, and Sentinel-1 images to assess elevation changes in summer season. Preliminary result, obtained by TerraSAR-X InSAR analysis, clearly delineates subsidence during the summer by identifying thousands of coherent pixels on ...

  17. Anti–SARS-CoV Immunoglobulin G in Healthcare Workers, Guangzhou, China

    OpenAIRE

    Chen, Wei-Qing; Lu, Ci-Yong; Wong, Tze-wai; Ling, Wen-Hua; Lin, Zhong-Ning; Hao, Yuan-Tao; LIU, Qing; Fang, Ji-Qian; He, Yun; Luo, Fu-Tian; Jing, Jin; Ling, Li; Ma, Xiang; Liu, Yi-Min; Chen, Gui-Hua

    2005-01-01

    To determine the prevalence of inapparent infection with severe acute respiratory syndrome (SARS) among healthcare workers, we performed a serosurvey to test for immunoglobulin (Ig) G antibodies to the SARS coronavirus (SARS-CoV) among 1,147 healthcare workers in 3 hospitals that admitted SARS patients in mid-May 2003. Among them were 90 healthcare workers with SARS. As a reference group, 709 healthcare workers who worked in 2 hospitals that never admitted any SARS patients were similarly tes...

  18. Wetlands Maps of Central Canada based on L-band SAR Imagery

    Science.gov (United States)

    Whitcomb, J.; Moghaddam, M.; Clewley, D.; McDonald, K. C.; Podest, E.; Chapman, B. D.

    2013-12-01

    Many boreal wetlands appear to be evolving into significant sources of greenhouse gases. The ability to accurately quantify the locations, types, and extents of northern wetlands is important to understanding their role in the global carbon cycle and responses to changes in climate. However, due to the extent of boreal wetlands and their inaccessibility, there have been few maps produced of this important ecosystem. To address this need, we have been constructing high-resolution (100 m) thematic maps of North American boreal wetlands. The maps are developed using space-based synthetic aperture radar (SAR), which is capable of efficiently providing high-resolution imagery of vast and often inaccessible regions. Unlike optical imagery, space-based SAR imagery is unaffected by cloud cover. Additionally, L-band SAR is able to sense vegetation structure and moisture content, as well as ground and surface water characteristics (even under vegetation canopies), thereby providing information unobtainable from optical sensors. Space-based L-band SAR thus constitutes an excellent tool for mapping boreal wetlands. One wetlands map is based on HH-polarized L-band SAR imagery from the Japanese Earth Resources Satellite (JERS-1), collected for both summer and winter in the late 1990s. A second map is based on dual-polarized (HH and HV) imagery from the Phased Array L-band SAR (PALSAR) sensor, collected in the summer of 2007. Prior to classification, a sequence of preprocessing steps are executed, including filtering, mosaicking, resampling, reprojection, co-registration, and the formation of supplementary data layers such as image texture, topographic slope, and proximity to water. This preprocessing is implemented by a semi-automated software suite specifically designed to handle the large volumes of data involved in the project. Training/testing data needed in the classification process are formed by merging national wetland inventory and land cover databases. Finally, a

  19. Landslide Deformation Analysis by Coupling Deformation Time Series from SAR Data with Hydrological Factors through Data Assimilation

    Directory of Open Access Journals (Sweden)

    Yanan Jiang

    2016-02-01

    Full Text Available Time-series SAR/InSAR techniques have proven to be effective tools for measuring landslide movements over large regions. Prior studies of these techniques, however, have focused primarily on technical innovation and applications, leaving coupling analysis of slope displacements and trigging factors as an unexplored area of research. Linking potential landslide inducing factors such as hydrology to SAR/InSAR derived displacements is of crucial importance for understanding landslide deformation mechanisms and could support the development of early-warning systems for disaster mitigation and management. In this study, a sequential data assimilation method named the Ensemble Kalman filter (EnKF, is adopted to explore the response mechanisms of the Shuping landslide movement in relation to hydrological factors. Previous research on the Shuping landslide area shows that the reservoir water level and rainfall are the two main triggering factors in slope failures. To extract the time-series deformations for the Shuping landslide area, Pixel Offset Tracking (POT technique with corner reflectors was adopted to process the TerraSAR-X StripMap (SM and High-resolution Spotlight (HS images. Considering that these triggering factors are the primary causes of displacement fluctuations in periodic displacement, time-series decomposition was carried out to extract the periodic displacement from the POT measurements. The correlations between the periodic displacement and the inducing factors were qualitatively estimated through a grey relational analysis. Based on this analysis, the EnKF method was adopted to explore the response relationships between the displacements and triggering factors. Preliminary results demonstrate the effectiveness of EnKF in studying deformation response mechanisms and understanding landslide development processes.

  20. SarA is a repressor of hla (alpha-hemolysin) transcription in Staphylococcus aureus: its apparent role as an activator of hla in the prototype strain NCTC 8325 depends on reduced expression of sarS.

    Science.gov (United States)

    Oscarsson, Jan; Kanth, Anna; Tegmark-Wisell, Karin; Arvidson, Staffan

    2006-12-01

    In most Staphylococcus aureus strains, inactivation of sarA increases hla transcription, indicating that sarA is a repressor. However, in S. aureus NCTC 8325 and its derivatives, used for most studies of hla regulation, inactivation of sarA resulted in decreased hla transcription. The disparate phenotype of strain NCTC 8325 seems to be associated with its rsbU mutation, which leads to sigma(B) deficiency. This has now been verified by the demonstration that sarA repressed hla transcription in an rsbU+ derivative of strain 8325-4 (SH1000). That sarA could act as a repressor of hla in an 8325-4 background was confirmed by the observation that inactivation of sarA in an agr sarS rot triple mutant dramatically increased hla transcription to wild-type levels. However, the apparent role of sarA as an activator of hla in 8325-4 was not a result of the rsbU mutation alone, as inactivation of sarA in another rsbU mutant, strain V8, led to increased hla transcription. Northern blot analysis revealed much higher levels of sarS mRNA in strain V8 than in 8325-4, which was likely due to the mutation in the sarS activator, tcaR, in 8325-4, which was not found in strain V8. On the other hand, the relative increase in sarS transcription upon the inactivation of sarA was 15-fold higher in 8325-4 than in strain V8. Because of this, inactivation of sarA in 8325-4 means a net increase in repressor activity, whereas in strain V8, inactivation of sarA means a net decrease in repressor activity and, therefore, enhanced hla transcription.

  1. MULTI-TEMPORAL SAR INTERFEROMETRY FOR LANDSLIDE MONITORING

    Directory of Open Access Journals (Sweden)

    R. Dwivedi

    2016-06-01

    Full Text Available In the past few years, SAR Interferometry specially InSAR and D-InSAR were extensively used for deformation monitoring related applications. Due to temporal and spatial decorrelation in dense vegetated areas, effectiveness of InSAR and D-InSAR observations were always under scrutiny. Multi-temporal InSAR methods are developed in recent times to retrieve the deformation signal from pixels with different scattering characteristics. Presently, two classes of multi-temporal InSAR algorithms are available- Persistent Scatterer (PS and Small Baseline (SB methods. This paper discusses the Stanford Method for Persistent Scatterer (StaMPS based PS-InSAR and the Small Baselines Subset (SBAS techniques to estimate the surface deformation in Tehri dam reservoir region in Uttarkhand, India. Both PS-InSAR and SBAS approaches used sixteen ENVISAT ASAR C-Band images for generating single master and multiple master interferograms stack respectively and their StaMPS processing resulted in time series 1D-Line of Sight (LOS mean velocity maps which are indicative of deformation in terms of movement towards and away from the satellites. From 1D LOS velocity maps, localization of landslide is evident along the reservoir rim area which was also investigated in the previous studies. Both PS-InSAR and SBAS effectively extract measurement pixels in the study region, and the general results provided by both approaches show a similar deformation pattern along the Tehri reservoir region. Further, we conclude that StaMPS based PS-InSAR method performs better in terms of extracting more number of measurement pixels and in the estimation of mean Line of Sight (LOS velocity as compared to SBAS method. It is also proposed to take up a few major landslides area in Uttarakhand for slope stability assessment.

  2. Satellite on-board real-time SAR processor prototype

    Science.gov (United States)

    Bergeron, Alain; Doucet, Michel; Harnisch, Bernd; Suess, Martin; Marchese, Linda; Bourqui, Pascal; Desnoyers, Nicholas; Legros, Mathieu; Guillot, Ludovic; Mercier, Luc; Châteauneuf, François

    2017-11-01

    A Compact Real-Time Optronic SAR Processor has been successfully developed and tested up to a Technology Readiness Level of 4 (TRL4), the breadboard validation in a laboratory environment. SAR, or Synthetic Aperture Radar, is an active system allowing day and night imaging independent of the cloud coverage of the planet. The SAR raw data is a set of complex data for range and azimuth, which cannot be compressed. Specifically, for planetary missions and unmanned aerial vehicle (UAV) systems with limited communication data rates this is a clear disadvantage. SAR images are typically processed electronically applying dedicated Fourier transformations. This, however, can also be performed optically in real-time. Originally the first SAR images were optically processed. The optical Fourier processor architecture provides inherent parallel computing capabilities allowing real-time SAR data processing and thus the ability for compression and strongly reduced communication bandwidth requirements for the satellite. SAR signal return data are in general complex data. Both amplitude and phase must be combined optically in the SAR processor for each range and azimuth pixel. Amplitude and phase are generated by dedicated spatial light modulators and superimposed by an optical relay set-up. The spatial light modulators display the full complex raw data information over a two-dimensional format, one for the azimuth and one for the range. Since the entire signal history is displayed at once, the processor operates in parallel yielding real-time performances, i.e. without resulting bottleneck. Processing of both azimuth and range information is performed in a single pass. This paper focuses on the onboard capabilities of the compact optical SAR processor prototype that allows in-orbit processing of SAR images. Examples of processed ENVISAT ASAR images are presented. Various SAR processor parameters such as processing capabilities, image quality (point target analysis), weight and

  3. Integrated Use of Multi-temporal SAR and Optical Satellite Imagery for Crop Mapping in Ukraine

    Science.gov (United States)

    Lavreniuk, M. S.; Kussul, N.; Skakun, S.

    2014-12-01

    Information on location and spatial distribution of crops is extremely important within many applications such as crop area estimation, crop yield forecasting and environmental impact analysis [1-2]. Synthetic-aperture radar (SAR) instruments on board remote sensing satellites offer unique features to imaging crops due to their all weather capabilities and ability to capture crop characteristics not available by optical instruments. This abstract aims to explore feasibility and the use of multi-temporal multi-polarization SAR images along with multi-temporal optical images to crop classification in Ukraine using a neural network ensemble. The study area included a JECAM test site in Ukraine which is a part of the Global Agriculture Monitoring (GEOGLAM) initiative. Six optical images were acquired by Landsat-8, and twelve SAR images were acquired by Radarsat-2 (six in FQ8W mode with angle 28 deg., and FQ20W with angle 40 deg.) over the study region. Optical images were atmospherically corrected. SAR images were filtered for speckle, and converted to backscatter coefficients. Ground truth data on crop type (274 polygons) were collected during the summer of 2013. In order to perform supervised classification of multi-temporal satellite imagery, an ensemble of neural networks, in particular multi-layer perceptrons (MLPs), was used. The use of the ensemble allowed us to improve overall (OA) classification accuracy from +0.1% to +2% comparing to an individual network. Adding multi-temporal SAR images to multi-temporal optical images improved both OA and individual class accuracies, in particular for sunflower (gains up to +25.9%), soybeans (+16.2%), and maize (+6.2%). It was also found that better OA can be obtained using shallow angle (FQ20W, 40°) OA=77% over steeper angle (FQ8W, 28°) OA=71.78%. 1. F. Kogan et al., "Winter wheat yield forecasting in Ukraine based on Earth observation, meteorological data and biophysical models," Int. J. Appl. Earth Observ. Geoinform

  4. Randomized Filtering Algorithms

    DEFF Research Database (Denmark)

    Katriel, Irit; Van Hentenryck, Pascal

    2008-01-01

    of AllDifferent and is generalization, the Global Cardinality Constraint. The first delayed filtering scheme is a Monte Carlo algorithm: its running time is superior, in the worst case, to that of enforcing are consistency after every domain event, while its filtering effectiveness is analyzed...

  5. Multilevel ensemble Kalman filter

    KAUST Repository

    Chernov, Alexey

    2016-01-06

    This work embeds a multilevel Monte Carlo (MLMC) sampling strategy into the Monte Carlo step of the ensemble Kalman filter (EnKF). In terms of computational cost vs. approximation error the asymptotic performance of the multilevel ensemble Kalman filter (MLEnKF) is superior to the EnKF s.

  6. Updating the OMERACT filter

    DEFF Research Database (Denmark)

    Wells, George; Beaton, Dorcas E; Tugwell, Peter

    2014-01-01

    The "Discrimination" part of the OMERACT Filter asks whether a measure discriminates between situations that are of interest. "Feasibility" in the OMERACT Filter encompasses the practical considerations of using an instrument, including its ease of use, time to complete, monetary costs, and inter...

  7. Fast Anisotropic Gauss Filtering

    NARCIS (Netherlands)

    Geusebroek, J.M.; Smeulders, A.W.M.; van de Weijer, J.; Heyden, A.; Sparr, G.; Nielsen, M.; Johansen, P.

    2002-01-01

    We derive the decomposition of the anisotropic Gaussian in a one dimensional Gauss filter in the x-direction followed by a one dimensional filter in a non-orthogonal direction phi. So also the anisotropic Gaussian can be decomposed by dimension. This appears to be extremely efficient from a

  8. Vena cava filter; Vena-cava-Filter

    Energy Technology Data Exchange (ETDEWEB)

    Helmberger, T. [Klinikum Bogenhausen, Institut fuer Diagnostische und Interventionelle Radiologie und Nuklearmedizin, Muenchen (Germany)

    2007-05-15

    Fulminant pulmonary embolism is one of the major causes of death in the Western World. In most cases, deep leg and pelvic venous thrombosis are the cause. If an anticoagulant/thrombotic therapy is no longer possible or ineffective, a vena cava filter implant may be indicated if an embolism is threatening. Implantation of the filter is a simple and safe intervention. Nevertheless, it is necessary to take into consideration that the data base for determining the indications for this treatment are very limited. Currently, a reduction in the risk of thromboembolism with the use of filters of about 30%, of recurrences of almost 5% and fatal pulmonary embolism of 1% has been reported, with a risk of up to 20% of filter induced vena cava thrombosis. (orig.) [German] Die fulminante Lungenembolie zaehlt zu den Haupttodesursachen in der westlichen Welt. In der Mehrzahl der Faelle sind tiefe Bein- und Beckenvenenthrombosen ursaechlich verantwortlich. Ist eine antikoagulative/-thrombotische Therapie nicht (mehr) moeglich oder unwirksam, kann bei drohender Emboliegefahr die Vena-cava-Filterimplantation indiziert sein. Die Filterimplantation ist eine einfache und sehr sichere Intervention. Dennoch muss bei der Indikationsstellung beruecksichtigt werden, dass die Datenlage zur Wirksamkeit sehr limitiert ist. So wird aktuell ueber eine Reduktion des Thrombembolierisikos um 30% bei Embolierezidiven von knapp 5% und fatalen Lungenembolien von 1% unter Filterprophylaxe berichtet, bei einem Risiko von bis zu 20% fuer die filterinduzierte Vena-cava-Thrombose. (orig.)

  9. Coral reef detection using SAR/RADARSAT-1 images at Costa dos Corais, PE/AL, Brazil

    Directory of Open Access Journals (Sweden)

    Frederico de Moraes Rudorff

    2008-06-01

    Full Text Available The present work aimed to examine the potentials of SAR RADARSAT-1 images to detect emergent coral reefs at the Environmental Protection Area of "Costa dos Corais". Multi-view filters were applied and tested for speckle noise reduction. A digital unsupervised classification based on image segmentation was performed and the classification accuracy was evaluated by an error matrix built between the SAR image classification and a reference map obtained from a TM Landsat-5 classification. The adaptative filters showed the best results for speckle suppression and border preservation, especially the Kuan, Gamma MAP, Lee, Frost and Enhanced Frost filters. Small similarity and area thresholds (5 and 10, respectively were used for the image segmentation due to the reduced dimensions and the narrow and elongated forms of the reefs. The classification threshold of 99% had a better user's accuracy, but a lower producer's accuracy because it is a more restrictive threshold; therefore, it may be possible that it had a greater omission on reef classification. The results indicate that SAR images have a good potential for the detection of emergent coral reefs.O presente trabalho examinou o potencial de imagens SAR do RADARSAT-1 na detecção de recifes de coral expostos na Área de Proteção Ambiental das Costa dos Corais. Filtros de multi-visada foram aplicados e testados para redução do ruído speckle. Uma classificação não supervisionada baseada em uma imagem segmentada foi realizada e a acurácia da classificação foi avaliada através de uma matriz de erro construída entre a imagem classificada e o mapa de referência. Os filtros adaptativos apresentaram os melhores desempenhos para supressão de speckle e preservação de bordas, especialmente os filtros Kuan, Gamma MAP, Lee, Frost and Enhanced Frost. Os pequenos limiares de similaridade e de área (10 e 5, respectivamente foram melhores devido à forma fina e alongada dos recifes. O limiar de

  10. Converses amb Cèsar Coll

    OpenAIRE

    Valls, Enric

    1992-01-01

    sar Coll i Salvador, Catedràtic de Psicologia Evolutiva i de l'Educació a la Facultat de Psicologia de la Universitat de Barcelona, ha estat al capdavant de la Reforma educativa des dels primers moments, com a redactor del Marc curricular per a l'ensenyament obligatori (Barcelona, 1986), com a propulsor de la reflexió per a l'elaboració dels dissenys curriculars, com a coordinador d'un grup de discussió i recerca per al desenvolupament del currículum a la Universitat, com a consultor de ref...

  11. sar Aira y el exotismo

    Directory of Open Access Journals (Sweden)

    Ricardo Gutiérrez-Mouat

    2013-07-01

    Full Text Available The present paper analyses one of the less commonly studied aspects of the poetics of César Aira: exoticism, which in Aira stems from the unstable and paradoxical place proper of a post-modern writer from the Rio de la Plata facing traditional (and European representations of exoticism in a period of cultural globalisation. The paper examines such a paradox and concludes that Aira’s exoticism is manifest in the ethnographic simulation and in certain thoughts on the de-familiarisation of the mother tongue.

  12. Topaz II Nuclear Powered SAR Satellite

    OpenAIRE

    Feuerstein, M.; Agrawal, B.N.

    1994-01-01

    The article of record as published may be found at http://dx.doi.org/10.2514/6.1994-4688 The AA4871 Spacecraft Design course is the capstone class for the M.S. in Astronautics at the Naval Postgraduate School. Thc design team integrated a Topaz If nuclear power system with an EOS Synthetic Aperture Radar to design a low Earth orbit, three axis stabilized satellite flying in a gravity gradient stable orientation. The SAR is a high resolution, electronically stecrable, Earth scie...

  13. Cloaked similarity between HIV-1 and SARS-CoV suggests an anti-SARS strategy

    Directory of Open Access Journals (Sweden)

    Kliger Yossef

    2003-09-01

    Full Text Available Abstract Background Severe acute respiratory syndrome (SARS is a febrile respiratory illness. The disease has been etiologically linked to a novel coronavirus that has been named the SARS-associated coronavirus (SARS-CoV, whose genome was recently sequenced. Since it is a member of the Coronaviridae, its spike protein (S2 is believed to play a central role in viral entry by facilitating fusion between the viral and host cell membranes. The protein responsible for viral-induced membrane fusion of HIV-1 (gp41 differs in length, and has no sequence homology with S2. Results Sequence analysis reveals that the two viral proteins share the sequence motifs that construct their active conformation. These include (1 an N-terminal leucine/isoleucine zipper-like sequence, and (2 a C-terminal heptad repeat located upstream of (3 an aromatic residue-rich region juxtaposed to the (4 transmembrane segment. Conclusions This study points to a similar mode of action for the two viral proteins, suggesting that anti-viral strategy that targets the viral-induced membrane fusion step can be adopted from HIV-1 to SARS-CoV. Recently the FDA approved Enfuvirtide, a synthetic peptide corresponding to the C-terminal heptad repeat of HIV-1 gp41, as an anti-AIDS agent. Enfuvirtide and C34, another anti HIV-1 peptide, exert their inhibitory activity by binding to a leucine/isoleucine zipper-like sequence in gp41, thus inhibiting a conformational change of gp41 required for its activation. We suggest that peptides corresponding to the C-terminal heptad repeat of the S2 protein may serve as inhibitors for SARS-CoV entry.

  14. Analog active filters

    Science.gov (United States)

    Ghausi, M. S.

    1984-01-01

    The evolution of active filters during the time from 1920 to 1980 is considered, taking into account the hardware used to implement a filtering network for voice frequency over 60 years. From 1920 to 1960 the majority of voice-frequency filters was realized as discrete RLC networks. After the development of transistors, it was realized that size and cost reductions could be achieved by replacing the inductors with active networks. In the early 1970's, batch-processed thin-film hybrid integrated circuits began to be employed. The synthesis of transfer functions which are predominantly input/output types is considered. Attention is given to direct realizations, synthesis using component simulation, cascade synthesis, multiple-loop feedback design, active-R and active-C filters, aspects of sensitivity, and switched-capacitor filters.

  15. Learning Separable Filters.

    Science.gov (United States)

    Sironi, Amos; Tekin, Bugra; Rigamonti, Roberto; Lepetit, Vincent; Fua, Pascal

    2015-01-01

    Learning filters to produce sparse image representations in terms of over-complete dictionaries has emerged as a powerful way to create image features for many different purposes. Unfortunately, these filters are usually both numerous and non-separable, making their use computationally expensive. In this paper, we show that such filters can be computed as linear combinations of a smaller number of separable ones, thus greatly reducing the computational complexity at no cost in terms of performance. This makes filter learning approaches practical even for large images or 3D volumes, and we show that we significantly outperform state-of-the-art methods on the curvilinear structure extraction task, in terms of both accuracy and speed. Moreover, our approach is general and can be used on generic convolutional filter banks to reduce the complexity of the feature extraction step.

  16. Calibration of a High Resolution Airborne 3-D SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Grinder-Pedersen, Jan; Madsen, S.N.

    1997-01-01

    The potential of across-track interferometric (XTI) synthetic aperture radar (SAR) for producing high resolution 3D imagery has been demonstrated by several airborne systems including EMISAR, the dual frequency, polarimetric, and interferometric SAR developed at the Dept. of Electromagnetic Systems...

  17. Understanding the T cell immune response in SARS coronavirus infection.

    Science.gov (United States)

    Janice Oh, Hsueh-Ling; Ken-En Gan, Samuel; Bertoletti, Antonio; Tan, Yee-Joo

    2012-09-01

    The severe acute respiratory syndrome (SARS) epidemic started in late 2002 and swiftly spread across 5 continents with a mortality rate of around 10%. Although the epidemic was eventually controlled through the implementation of strict quarantine measures, there continues a need to investigate the SARS coronavirus (SARS-CoV) and develop interventions should it re-emerge. Numerous studies have shown that neutralizing antibodies against the virus can be found in patients infected with SARS-CoV within days upon the onset of illness and lasting up to several months. In contrast, there is little data on the kinetics of T cell responses during SARS-CoV infection and little is known about their role in the recovery process. However, recent studies in mice suggest the importance of T cells in viral clearance during SARS-CoV infection. Moreover, a growing number of studies have investigated the memory T cell responses in recovered SARS patients. This review covers the available literature on the emerging importance of T cell responses in SARS-CoV infection, particularly on the mapping of cytotoxic T lymphocyte (CTL) epitopes, longevity, polyfunctionality and human leukocyte antigen (HLA) association as well as their potential implications on treatment and vaccine development.

  18. Agricultural Performance Monitoring with Polarimetric SAR and Optical Imagery

    Science.gov (United States)

    Dhar, T.; Gray, D.; Menges, C.

    2009-04-01

    This paper presents the results from an experiment measuring yield using TerraSAR-X dual-polarimetric mode and precision agriculture machinery which records harvested amounts every few meters. The experimental field setup and data collection using TerraSAR-X are discussed and some preliminary results are shown.

  19. The Danish polarimetric SAR for remote sensing applications

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz; Madsen, Søren Nørvang; Dall, Jørgen

    1994-01-01

    Presents the Danish polarimetric SAR system, EMISAR, and the approach taken in the system design to achieve a reliable high performance system. The design and implementation of the antenna system as well as the analog and digital hardware are discussed. The SAR utilises a dual polarised microstri...

  20. Genome organization of the SARS-CoV

    DEFF Research Database (Denmark)

    Xu, Jing; Hu, Jianfei; Wang, Jing

    2003-01-01

    Annotation of the genome sequence of the SARS-CoV (severe acute respiratory syndrome-associated coronavirus) is indispensable to understand its evolution and pathogenesis. We have performed a full annotation of the SARS-CoV genome sequences by using annotation programs publicly available or devel...

  1. Understanding the T cell immune response in SARS coronavirus infection

    Science.gov (United States)

    Janice Oh, Hsueh-Ling; Ken-En Gan, Samuel; Bertoletti, Antonio; Tan, Yee-Joo

    2012-01-01

    The severe acute respiratory syndrome (SARS) epidemic started in late 2002 and swiftly spread across 5 continents with a mortality rate of around 10%. Although the epidemic was eventually controlled through the implementation of strict quarantine measures, there continues a need to investigate the SARS coronavirus (SARS-CoV) and develop interventions should it re-emerge. Numerous studies have shown that neutralizing antibodies against the virus can be found in patients infected with SARS-CoV within days upon the onset of illness and lasting up to several months. In contrast, there is little data on the kinetics of T cell responses during SARS-CoV infection and little is known about their role in the recovery process. However, recent studies in mice suggest the importance of T cells in viral clearance during SARS-CoV infection. Moreover, a growing number of studies have investigated the memory T cell responses in recovered SARS patients. This review covers the available literature on the emerging importance of T cell responses in SARS-CoV infection, particularly on the mapping of cytotoxic T lymphocyte (CTL) epitopes, longevity, polyfunctionality and human leukocyte antigen (HLA) association as well as their potential implications on treatment and vaccine development. PMID:26038429

  2. An Adaptive Ship Detection Scheme for Spaceborne SAR Imagery

    Directory of Open Access Journals (Sweden)

    Xiangguang Leng

    2016-08-01

    Full Text Available With the rapid development of spaceborne synthetic aperture radar (SAR and the increasing need of ship detection, research on adaptive ship detection in spaceborne SAR imagery is of great importance. Focusing on practical problems of ship detection, this paper presents a highly adaptive ship detection scheme for spaceborne SAR imagery. It is able to process a wide range of sensors, imaging modes and resolutions. Two main stages are identified in this paper, namely: ship candidate detection and ship discrimination. Firstly, this paper proposes an adaptive land masking method using ship size and pixel size. Secondly, taking into account the imaging mode, incidence angle, and polarization channel of SAR imagery, it implements adaptive ship candidate detection in spaceborne SAR imagery by applying different strategies to different resolution SAR images. Finally, aiming at different types of typical false alarms, this paper proposes a comprehensive ship discrimination method in spaceborne SAR imagery based on confidence level and complexity analysis. Experimental results based on RADARSAT-1, RADARSAT-2, TerraSAR-X, RS-1, and RS-3 images demonstrate that the adaptive scheme proposed in this paper is able to detect ship targets in a fast, efficient and robust way.

  3. Tropical forest mapping using polarimetric and interferometric SAR data

    NARCIS (Netherlands)

    Prakoso, K.U.

    2006-01-01

    A study was made of the potential of the combined use of C-, L- and P-band polarimetric and C- and L-band interferometric airborne SAR data for tropical forest mapping. These data were collected with the NASA/JPL AirSAR during the PacRim-2 2000 campaign in Indonesia. The Sungai Wain forest reserve

  4. Comparing satellite SAR and wind farm wake models

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Vincent, P.; Husson, R.

    2015-01-01

    . These extend several tens of kilometres downwind e.g. 70 km. Other SAR wind maps show near-field fine scale details of wake behind rows of turbines. The satellite SAR wind farm wake cases are modelled by different wind farm wake models including the PARK microscale model, the Weather Research and Forecasting...

  5. Signal Processing for High Resolution FMCW SAR and Moving Target

    NARCIS (Netherlands)

    Meta, A.; Hoogeboom, P.

    2005-01-01

    The combination of Frequency Modulated ContinuousWave (FMCW) technology and Synthetic Aperture Radar (SAR) leads to lightweight, cost-effective imaging sensors of high resolution. In FMCW SAR applications the conventional stop-and-go approximation used in pulse radar algorithms cannot be considered

  6. Reliability of SAR ADCs and associated embedded instrument detection

    NARCIS (Netherlands)

    Wan, J.; Kerkhoff, Hans G.

    2015-01-01

    Successive-approximation-register (SAR) analog-to-digital converters (ADCs) represent the majority of the ADC market from medium to high resolution ADCs. Due to its low power, high-performance and small area in Mega-Hz range, SAR ADCs are increasingly attractive for todays safe-critical applications

  7. The Recent Severe Acute Respiratory Syndrome (SARS) Epidemic ...

    African Journals Online (AJOL)

    It is a syndrome characterized by fever, cough, sore throat , shortness of breath and malaise which may deteriorate very rapidly to respiratory failure and death. The symptoms of SARS are quite similar to those of common cold, malaria and respiratory tract infections all of which are common in our environment. SARS, being ...

  8. Training Convolutional Neural Networks for Translational Invariance on SAR ATR

    DEFF Research Database (Denmark)

    Malmgren-Hansen, David; Engholm, Rasmus; Østergaard Pedersen, Morten

    2016-01-01

    In this paper we present a comparison of the robustness of Convolutional Neural Networks (CNN) to other classifiers in the presence of uncertainty of the objects localization in SAR image. We present a framework for simulating simple SAR images, translating the object of interest systematically...

  9. Ionospheric effects on repeat-pass SAR interferometry

    Science.gov (United States)

    Feng, Jian; Zhen, Weimin; Wu, Zhensen

    2017-10-01

    InSAR measurements can be significantly affected by the atmosphere when the radar signal propagates through the atmosphere since it varies with space and time. Great efforts have been made in recent years to better understand the properties of the tropospheric effects and to develop methods for mitigating these effects. By using the basic principles of InSAR, the quantitative analysis of ionospheric delay effects on topography and surface deformation have been introduced for the first time. The measurement errors can be related to the vertical ionospheric total electron content (vTEC). By using the ionospheric observations, the effects of temporal ionospheric variations on InSAR have been analyzed. The results indicate that the ionospheric variations with time, season, solar cycle and geomagnetic activities can compromise the effectiveness of InSAR for both the measurement of topography and surface determination. The repeat-pass SAR interferometry errors induced by ionosphere should be corrected by actual measurements.

  10. Ice flow mapping with P-band SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Nielsen, Ulrik; Kusk, Anders

    2013-01-01

    -band SAR data have been acquired in Greenland, and both offset tracking and DInSAR have been applied to the full resolution data as well as to data degraded to the resolution of Biomass. Generally, ice velocity maps are successfully generated, but in the ablation zone, DInSAR fails in the melt season......Glacier and ice sheet dynamics are currently mapped with X-, C-, and L-band SAR. With the prospect of a P-band SAR, Biomass, to be launched within the next decade it is interesting to look into the potential of P-band for ice velocity mapping. In this paper first results are presented. Airborne P...

  11. INVENTORY OF IRRIGATED RICE ECOSYSTEM USING POLARIMETRIC SAR DATA

    Directory of Open Access Journals (Sweden)

    P. Srikanth

    2012-08-01

    Full Text Available An attempt has been made in the current study to assess the potential of polarimetric SAR data for inventory of kharif rice and the major competing crop like cotton. In the process, physical process of the scattering mechanisms occurring in rice and cotton crops at different phonological stages was studied through the use of temporal Radarsat 2 Fine quadpol SAR data. The temporal dynamics of the volume, double and odd bounce, entropy, anisotropy, alpha parameters and polarimertic signatures, classification through isodata clustering and Wishart techniques were assessed. The Wishart (H-a classification showed higher overall as well as rice and cotton crop accuracies compared to the isodata clustering from Freeman 3-component decomposition. The classification of temporal SAR data sets independently showed that the rice crop forecasting can be advanced with the use of appropriate single date polarimetric SAR data rather than using temporal SAR amplitude data sets with the single polarization in irrigated rice ecosystems

  12. Receptor recognition and cross-species infections of SARS coronavirus

    Science.gov (United States)

    Li, Fang

    2013-01-01

    Receptor recognition is a major determinant of the host range, cross-species infections, and pathogenesis of the severe acute respiratory syndrome coronavirus (SARS-CoV). A defined receptor-binding domain (RBD) in the SARS-CoV spike protein specifically recognizes its host receptor, angiotensin-converting enzyme 2 (ACE2). This article reviews the latest knowledge about how RBDs from different SARS-CoV strains interact with ACE2 from several animal species. Detailed research on these RBD/ACE2 interactions has established important principles on host receptor adaptations, cross-species infections, and future evolution of SARS-CoV. These principles may apply to other emerging animal viruses, including the recently emerged Middle East respiratory syndrome coronavirus (MERS-CoV). This paper forms part of a series of invited articles in Antiviral Research on “From SARS to MERS: 10 years of research on highly pathogenic human coronaviruses.” PMID:23994189

  13. Method for providing a polarization filter for processing synthetic aperture radar image data

    Science.gov (United States)

    Dubois, Pascale C. (Inventor); vanZyl, Jakob J. (Inventor)

    1991-01-01

    A polarization filter can maximize the signal-to-noise ratio of a polarimetric SAR and help discriminate between targets or enhance image features, e.g., enhance contract between different types of target. The method disclosed is based on the Stokes matrix/Stokes vector representation, so the targets of interest can be extended targets, and the method can also be applied to the case of bistatic polarimetric radars.

  14. SarT, a Repressor of α-Hemolysin in Staphylococcus aureus

    Science.gov (United States)

    Schmidt, Katherine A.; Manna, Adhar C.; Gill, Steven; Cheung, Ambrose L.

    2001-01-01

    In searching the Staphylococcus aureus genome, we found several homologs to SarA. One of these genes, sarT, codes for a basic protein with 118 residues and a predicted molecular size of 16,096 Da. Northern blot analysis revealed that the expression of sarT was repressed by sarA and agr. An insertion sarT mutant generated in S. aureus RN6390 and 8325-4 backgrounds revealed minimal effect on the expression of sarR and sarA. The RNAIII level was notably increased in the sarT mutant, particularly in postexponential-phase cells, while the augmentative effect on RNAII was less. SarT repressed the expression of α-hemolysin, as determined by Northern blotting, Western blotting, and a rabbit erythrocyte hemolytic assay. This repression was relieved upon complementation. Similar to agr and sarA mutants, which predictably displayed a reduction in hla expression, the agr sarT mutant exhibited a lower level of hla transcription than the sarT mutant. In contrast, hla transcription was enhanced in the sarA sarT mutant compared with the single sarA mutant. Collectively, these results indicated that the sarA locus, contrary to the regulatory action of agr, induced α-hemolysin production by repressing sarT, a repressor of hla transcription. PMID:11447147

  15. Real-time optical processor prototype for remote SAR applications

    Science.gov (United States)

    Marchese, Linda; Doucet, Michel; Harnisch, Bernd; Suess, Martin; Bourqui, Pascal; Legros, Mathieu; Desnoyers, Nichola; Guillot, Ludovic; Mercier, Luc; Savard, Maxime; Martel, Anne; Châteauneuf, François; Bergeron, Alain

    2009-09-01

    A Compact Real-Time Optical SAR Processor has been successfully developed and tested. SAR, or Synthetic Aperture Radar, is a powerful tool providing enhanced day and night imaging capabilities. SAR systems typically generate large amounts of information generally in the form of complex data that are difficult to compress. Specifically, for planetary missions and unmanned aerial vehicle (UAV) systems with limited communication data rates this is a clear disadvantage. SAR images are typically processed electronically applying dedicated Fourier transformations. This, however, can also be performed optically in real-time. Indeed, the first SAR images have been optically processed. The optical processor architecture provides inherent parallel computing capabilities that can be used advantageously for the SAR data processing. Onboard SAR image generation would provide local access to processed information paving the way for real-time decision-making. This could eventually benefit navigation strategy and instrument orientation decisions. Moreover, for interplanetary missions, onboard analysis of images could provide important feature identification clues and could help select the appropriate images to be transmitted to Earth, consequently helping bandwidth management. This could ultimately reduce the data throughput requirements and related transmission bandwidth. This paper reviews the design of a compact optical SAR processor prototype that would reduce power, weight, and size requirements and reviews the analysis of SAR image generation using the table-top optical processor. Various SAR processor parameters such as processing capabilities, image quality (point target analysis), weight and size are reviewed. Results of image generation from simulated point targets as well as real satellite-acquired raw data are presented.

  16. Relations of SARS-Related Stressors and Coping to Chinese College Students' Psychological Adjustment during the 2003 Beijing SARS Epidemic

    Science.gov (United States)

    Main, Alexandra; Zhou, Qing; Ma, Yue; Luecken, Linda J.; Liu, Xin

    2011-01-01

    This study examined the main and interactive relations of stressors and coping related to severe acute respiratory syndrome (SARS) with Chinese college students' psychological adjustment (psychological symptoms, perceived general health, and life satisfaction) during the 2003 Beijing SARS epidemic. All the constructs were assessed by self-report…

  17. 3D Monitoring of Buildings Using TerraSAR-X InSAR, DInSAR and PolSAR Capacities

    Directory of Open Access Journals (Sweden)

    Flora Weissgerber

    2017-09-01

    Full Text Available The rapid expansion of cities increases the need of urban remote sensing for a large scale monitoring. This paper provides greater understanding of how TerraSAR-X (TSX high-resolution abilities enable to reach the spatial precision required to monitor individual buildings, through the use of a 4 year temporal stack of 100 images over Paris (France. Three different SAR modes are investigated for this purpose. First a method involving a whole time-series is proposed to measure realistic heights of buildings. Then, we show that the small wavelength of TSX makes the interferometric products very sensitive to the ordinary building-deformation, and that daily deformation can be measured over the entire building with a centimetric accuracy, and without any a priori on the deformation evolution, even when neglecting the impact of the atmosphere. Deformations up to 4 cm were estimated for the Eiffel Tower and up to 1 cm for other lower buildings. These deformations were analyzed and validated with weather and in situ local data. Finally, four TSX polarimetric images were used to investigate geometric and dielectric properties of buildings under the deterministic framework. Despite of the resolution loss of this mode, the possibility to estimate the structural elements of a building orientations and their relative complexity in the spatial organization are demonstrated.

  18. Rapid inactivation of SARS-like coronaviruses.

    Energy Technology Data Exchange (ETDEWEB)

    Kapil, Sanjay (Kansas State University, Manhattan, KS); Oberst, R. D. (Kansas State University, Manhattan, KS); Bieker, Jill Marie; Tucker, Mark David; Souza, Caroline Ann; Williams, Cecelia Victoria

    2004-03-01

    Chemical disinfection and inactivation of viruses is largely understudied, but is very important especially in the case of highly infectious viruses. The purpose of this LDRD was to determine the efficacy of the Sandia National Laboratories developed decontamination formulations against Bovine Coronavirus (BCV) as a surrogate for the coronavirus that causes Severe Acute Respiratory Syndrome (SARS) in humans. The outbreak of SARS in late 2002 resulted from a highly infectious virus that was able to survive and remain infectious for extended periods. For this study, preliminary testing with Escherichia coli MS-2 (MS-2) and Escherichia coli T4 (T4) bacteriophages was conducted to develop virucidal methodology for verifying the inactivation after treatment with the test formulations following AOAC germicidal methodologies. After the determination of various experimental parameters (i.e. exposure, concentration) of the formulations, final testing was conducted on BCV. All experiments were conducted with various organic challenges (horse serum, bovine feces, compost) for results that more accurately represent field use condition. The MS-2 and T4 were slightly more resistant than BCV and required a 2 minute exposure while BCV was completely inactivated after a 1 minute exposure. These results were also consistent for the testing conducted in the presence of the various organic challenges indicating that the test formulations are highly effective for real world application.

  19. Modelling of potentially promising SARS protease inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Plewczynski, Dariusz [Interdisciplinary Centre for Mathematical and Computational Modelling, ICM, Warsaw University, Pawinskiego 5a Street, 02-106 Warsaw (Poland); Hoffmann, Marcin [BioInfoBank Institute, Limanowskiego 24A/16, 60-744 Poznan (Poland); Grotthuss, Marcin von [BioInfoBank Institute, Limanowskiego 24A/16, 60-744 Poznan (Poland); Knizewski, Lukasz [Interdisciplinary Centre for Mathematical and Computational Modelling, ICM, Warsaw University, Pawinskiego 5a Street, 02-106 Warsaw (Poland); Rychewski, Leszek [BioInfoBank Institute, Limanowskiego 24A/16, 60-744 Poznan (Poland); Eitner, Krystian [BioInfoBank Institute, Limanowskiego 24A/16, 60-744 Poznan (Poland); Ginalski, Krzysztof [Interdisciplinary Centre for Mathematical and Computational Modelling, ICM, Warsaw University, Pawinskiego 5a Street, 02-106 Warsaw (Poland)

    2007-07-18

    In many cases, at the beginning of a high throughput screening experiment some information about active molecules is already available. Active compounds (such as substrate analogues, natural products and inhibitors of related proteins) are often identified in low throughput validation studies on a biochemical target. Sometimes the additional structural information is also available from crystallographic studies on protein and ligand complexes. In addition, the structural or sequence similarity of various protein targets yields a novel possibility for drug discovery. Co-crystallized compounds from homologous proteins can be used to design leads for a new target without co-crystallized ligands. In this paper we evaluate how far such an approach can be used in a real drug campaign, with severe acute respiratory syndrome (SARS) coronavirus providing an example. Our method is able to construct small molecules as plausible inhibitors solely on the basis of the set of ligands from crystallized complexes of a protein target, and other proteins from its structurally homologous family. The accuracy and sensitivity of the method are estimated here by the subsequent use of an electronic high throughput screening flexible docking algorithm. The best performing ligands are then used for a very restrictive similarity search for potential inhibitors of the SARS protease within the million compounds from the Ligand.Info small molecule meta-database. The selected molecules can be passed on for further experimental validation.

  20. Ceramic fiber reinforced filter

    Science.gov (United States)

    Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  1. The Ecosystems SAR (EcoSAR) an Airborne P-band Polarimetric InSAR for the Measurement of Vegetation Structure, Biomass and Permafrost

    Science.gov (United States)

    Rincon, Rafael F.; Fatoyinbo, Temilola; Ranson, K. Jon; Osmanoglu, Batuhan; Sun, Guoqing; Deshpande, Manohar D.; Perrine, Martin L.; Du Toit, Cornelis F.; Bonds, Quenton; Beck, Jaclyn; hide

    2014-01-01

    EcoSAR is a new synthetic aperture radar (SAR) instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. The instrument uses a phased-array beamforming architecture and supports full polarimetric measurements and single pass interferometry. This Instrument development is part of NASA's Earth Science Technology Office Instrument Incubator Program (ESTO IIP).

  2. Far infrared interference filters.

    Science.gov (United States)

    Varma, S P; Möller, K D

    1969-08-01

    Capacitive meshes for far ir, low pass filters are prepared from Cu layers on 2.5 micro plastic film. The properties of these meshes of different mesh constants g with their different combinations in two-mesh, fourmesh, and eight-mesh filters are studied in the spectral region 160 cm(-1) to 10 cm(-1) by the use of a grating spectrometer. The applications of these meshes as low pass filters in the far ir spectral region in a grating spectrometer are described.

  3. Circuits and filters handbook

    CERN Document Server

    Chen, Wai-Kai

    2003-01-01

    A bestseller in its first edition, The Circuits and Filters Handbook has been thoroughly updated to provide the most current, most comprehensive information available in both the classical and emerging fields of circuits and filters, both analog and digital. This edition contains 29 new chapters, with significant additions in the areas of computer-aided design, circuit simulation, VLSI circuits, design automation, and active and digital filters. It will undoubtedly take its place as the engineer's first choice in looking for solutions to problems encountered in the design, analysis, and behavi

  4. EMI filter design

    CERN Document Server

    Ozenbaugh, Richard Lee

    2011-01-01

    With today's electrical and electronics systems requiring increased levels of performance and reliability, the design of robust EMI filters plays a critical role in EMC compliance. Using a mix of practical methods and theoretical analysis, EMI Filter Design, Third Edition presents both a hands-on and academic approach to the design of EMI filters and the selection of components values. The design approaches covered include matrix methods using table data and the use of Fourier analysis, Laplace transforms, and transfer function realization of LC structures. This edition has been fully revised

  5. Paul Rodgersi filter Kohilas

    Index Scriptorium Estoniae

    2000-01-01

    28. I Kohila keskkoolis kohaspetsiifiline skulptuur ja performance "Filter". Kooli 130. aastapäeva tähistava ettevõtmise eesotsas oli skulptor Paul Rodgers ja kaks viimase klassi noormeest ئ Marko Heinmäe, Hendrik Karm.

  6. Perspectives on Nonlinear Filtering

    KAUST Repository

    Law, Kody

    2015-01-07

    The solution to the problem of nonlinear filtering may be given either as an estimate of the signal (and ideally some measure of concentration), or as a full posterior distribution. Similarly, one may evaluate the fidelity of the filter either by its ability to track the signal or its proximity to the posterior filtering distribution. Hence, the field enjoys a lively symbiosis between probability and control theory, and there are plenty of applications which benefit from algorithmic advances, from signal processing, to econometrics, to large-scale ocean, atmosphere, and climate modeling. This talk will survey some recent theoretical results involving accurate signal tracking with noise-free (degenerate) dynamics in high-dimensions (infinite, in principle, but say d between 103 and 108 , depending on the size of your application and your computer), and high-fidelity approximations of the filtering distribution in low dimensions (say d between 1 and several 10s).

  7. Updating the OMERACT filter

    DEFF Research Database (Denmark)

    D'Agostino, Maria-Antonietta; Boers, Maarten; Kirwan, John

    2014-01-01

    OBJECTIVE: The Outcome Measures in Rheumatology (OMERACT) Filter provides a framework for the validation of outcome measures for use in rheumatology clinical research. However, imaging and biochemical measures may face additional validation challenges because of their technical nature. The Imagin...

  8. Compact photonic spin filters

    Science.gov (United States)

    Ke, Yougang; Liu, Zhenxing; Liu, Yachao; Zhou, Junxiao; Shu, Weixing; Luo, Hailu; Wen, Shuangchun

    2016-10-01

    In this letter, we propose and experimentally demonstrate a compact photonic spin filter formed by integrating a Pancharatnam-Berry phase lens (focal length of ±f ) into a conventional plano-concave lens (focal length of -f). By choosing the input port of the filter, photons with a desired spin state, such as the right-handed component or the left-handed one, propagate alone its original propagation direction, while the unwanted spin component is quickly diverged after passing through the filter. One application of the filter, sorting the spin-dependent components of vector vortex beams on higher-order Poincaré sphere, is also demonstrated. Our scheme provides a simple method to manipulate light, and thereby enables potential applications for photonic devices.

  9. Spacial Variation in SAR Images of Different Resolution for Agricultural Fields

    DEFF Research Database (Denmark)

    Sandholt, Inge; Skriver, Henning

    1999-01-01

    The spatial variation in two types of Synthetic Aperture Radar (SAR) images covering agricultural fields is analysed. C-band polarimetric SAR data from the Danish airborne SAR, EMISAR, have been compared to space based ERS-1 C-band SAR with respect to scale and effect of polarization. The general...

  10. Filtered stochastic calculus

    OpenAIRE

    Lenczewski, Romuald

    2001-01-01

    By introducing a color filtration to the multiplicity space, we extend the quantum Ito calculus on multiple symmetric Fock space to the framework of filtered adapted biprocesses. In this new notion of adaptedness,``classical'' time filtration makes the integrands similar to adapted processes, whereas ``quantum'' color filtration produces their deviations from adaptedness. An important feature of this calculus, which we call filtered stochastic calculus, is that it provides an explicit interpo...

  11. A 12-bit SAR ADC integrated on a multichannel silicon drift detector readout IC

    Science.gov (United States)

    Schembari, F.; Bellotti, G.; Fiorini, C.

    2016-07-01

    A 12-bit analog-to-digital converter (ADC) addressed to Silicon-Drift Detectors (SDDs) multichannel readout ASICs for X- and gamma-ray applications is presented. Aiming at digitizing output multiplexed data from the upstream analog filters banks, the converter must ensure 11-bit accuracy and a sampling frequency of about 5 MS/s. The ADC architecture is the charge-redistribution (CR) successive-approximation register (SAR). A fully differential topology has also been chosen for better rejection of common-mode noise and disturbances. The internal DAC is made of binary-scaled capacitors, whose bottom plates are switched by the SAR logic to perform the binary search of the analog input value by means of the monotonic switching scheme. The A/D converter is integrated on SFERA, a multichannel ASIC fabricated in a standard CMOS 0.35 μm 3.3 V technology and it occupies an area of 0.42 mm2. Simulated static performance shows monotonicity over the whole input-output characteristic. The description of the circuit topology and of inner blocks architectures together with the experimental characterization is here presented.

  12. A study of the partial acquisition technique to reduce the amount of SAR data

    Science.gov (United States)

    Arief, Rahmat; Sudiana, Dodi; Ramli, Kalamullah

    2017-01-01

    Synthetic Aperture Radar (SAR) technology is capable to provide high resolution image data of earth surfaces from a moving vehicle. This causes large volumes of raw data. Many researchs were proposed about compressed radar imaging, which can reduce the sampling rate of the analog digital converter (ADC) on the receiver and eliminate the need of match filter on the radar receiver. Besides the advantages, there is a major problem that produces a large measurement matrix, which causes a very intensive matrix calculation. In this paper is studied a new approach to partial acquisition technique to reduce the amount of raw data using compressed sampling in both the azimuth and range and to reduce the computational load. The results showed that the reconstruction of SAR image using partial acquisition model has good resolution comparable to the conventional method (Range Doppler Algorithm). On a target of a ship, that represents a low level sparsity, a good reconstruction image could be achieved from a fewer number measurement. The method can speed up the computation time by a factor of 2.64 to 4.49 times faster than with a full acquisition matrix.

  13. RESEARCH ON AIRBORNE SAR IMAGING BASED ON ESC ALGORITHM

    Directory of Open Access Journals (Sweden)

    X. T. Dong

    2017-09-01

    Full Text Available Due to the ability of flexible, accurate, and fast obtaining abundant information, airborne SAR is significant in the field of Earth Observation and many other applications. Optimally the flight paths are straight lines, but in reality it is not the case since some portion of deviation from the ideal path is impossible to avoid. A small disturbance from the ideal line will have a major effect on the signal phase, dramatically deteriorating the quality of SAR images and data. Therefore, to get accurate echo information and radar images, it is essential to measure and compensate for nonlinear motion of antenna trajectories. By means of compensating each flying trajectory to its reference track, MOCO method corrects linear phase error and quadratic phase error caused by nonlinear antenna trajectories. Position and Orientation System (POS data is applied to acquiring accuracy motion attitudes and spatial positions of antenna phase centre (APC. In this paper, extend chirp scaling algorithm (ECS is used to deal with echo data of airborne SAR. An experiment is done using VV-Polarization raw data of C-band airborne SAR. The quality evaluations of compensated SAR images and uncompensated SAR images are done in the experiment. The former always performs better than the latter. After MOCO processing, azimuth ambiguity is declined, peak side lobe ratio (PSLR effectively improves and the resolution of images is improved obviously. The result shows the validity and operability of the imaging process for airborne SAR.

  14. Research on Airborne SAR Imaging Based on Esc Algorithm

    Science.gov (United States)

    Dong, X. T.; Yue, X. J.; Zhao, Y. H.; Han, C. M.

    2017-09-01

    Due to the ability of flexible, accurate, and fast obtaining abundant information, airborne SAR is significant in the field of Earth Observation and many other applications. Optimally the flight paths are straight lines, but in reality it is not the case since some portion of deviation from the ideal path is impossible to avoid. A small disturbance from the ideal line will have a major effect on the signal phase, dramatically deteriorating the quality of SAR images and data. Therefore, to get accurate echo information and radar images, it is essential to measure and compensate for nonlinear motion of antenna trajectories. By means of compensating each flying trajectory to its reference track, MOCO method corrects linear phase error and quadratic phase error caused by nonlinear antenna trajectories. Position and Orientation System (POS) data is applied to acquiring accuracy motion attitudes and spatial positions of antenna phase centre (APC). In this paper, extend chirp scaling algorithm (ECS) is used to deal with echo data of airborne SAR. An experiment is done using VV-Polarization raw data of C-band airborne SAR. The quality evaluations of compensated SAR images and uncompensated SAR images are done in the experiment. The former always performs better than the latter. After MOCO processing, azimuth ambiguity is declined, peak side lobe ratio (PSLR) effectively improves and the resolution of images is improved obviously. The result shows the validity and operability of the imaging process for airborne SAR.

  15. Very High Resolution SAR Tomography via Compressive Sensing

    Science.gov (United States)

    Zhu, Xiao Xiang; Bamler, Richard

    2010-03-01

    By using multi-pass SAR acquisitions, SAR tomography (TomoSAR) extends the synthetic aperture principle into the elevation direction for 3-D imaging. Since the orbits of modern space-borne SAR systems, like TerraSAR-X, are tightly controlled, the elevation resolution (depending on the elevation aperture size) is at least an order of magnitude lower than in range and azimuth. Hence, super- resolution algorithms are desired. The high anisotropic 3- D resolution element renders the signals sparse in elevation. This property suggests using compressive sensing (CS) methods. The paper presents the theory of 4- D (i.e. space-time) CS TomoSAR and compares it with classical tomographic methods. Super-resolution properties and point localization accuracies are demonstrated using simulations and real data. A CS reconstruction of a building complex from TerraSAR-X spotlight data is presented. In addition, the model based time warp method for differential tomographic non-linear motion monitoring is proposed and validated by reconstructing seasonal motion (caused by thermal expansion) of a building complex.

  16. Contactor/filter improvements

    Science.gov (United States)

    Stelman, David

    1989-01-01

    A contactor/filter arrangement for removing particulate contaminants from a gaseous stream includes a housing having a substantially vertically oriented granular material retention member with upstream and downstream faces, a substantially vertically oriented microporous gas filter element, wherein the retention member and the filter element are spaced apart to provide a zone for the passage of granular material therethrough. The housing further includes a gas inlet means, a gas outlet means, and means for moving a body of granular material through the zone. A gaseous stream containing particulate contaminants passes through the gas inlet means as well as through the upstream face of the granular material retention member, passing through the retention member, the body of granular material, the microporous gas filter element, exiting out of the gas outlet means. Disposed on the upstream face of the filter element is a cover screen which isolates the filter element from contact with the moving granular bed and collects a portion of the particulates so as to form a dust cake having openings small enough to exclude the granular material, yet large enough to receive the dust particles. In one embodiment, the granular material is comprised of prous alumina impregnated with CuO, with the cover screen cleaned by the action of the moving granular material as well as by backflow pressure pulses.

  17. Inorganic UV filters

    Directory of Open Access Journals (Sweden)

    Eloísa Berbel Manaia

    2013-06-01

    Full Text Available Nowadays, concern over skin cancer has been growing more and more, especially in tropical countries where the incidence of UVA/B radiation is higher. The correct use of sunscreen is the most efficient way to prevent the development of this disease. The ingredients of sunscreen can be organic and/or inorganic sun filters. Inorganic filters present some advantages over organic filters, such as photostability, non-irritability and broad spectrum protection. Nevertheless, inorganic filters have a whitening effect in sunscreen formulations owing to the high refractive index, decreasing their esthetic appeal. Many techniques have been developed to overcome this problem and among them, the use of nanotechnology stands out. The estimated amount of nanomaterial in use must increase from 2000 tons in 2004 to a projected 58000 tons in 2020. In this context, this article aims to analyze critically both the different features of the production of inorganic filters (synthesis routes proposed in recent years and the permeability, the safety and other characteristics of the new generation of inorganic filters.

  18. (abstract) The SIR-C/X-SAR Mission

    Science.gov (United States)

    Way, JoBea; Evans, Diane; Elachi, Charles

    1993-01-01

    The Shuttle Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) is a cooperative experiment between the National Aeronautics and Space Administration (NASA), the German Space Agency (DARA), and the Italian Space Agency (ASI). The experiment is the next evolutionary step in NASA's Spaceborne Imaging Radar (SIR) program that began with the Seasat SAR in 1978, and continued with SAR -A in 1981 and SAR-B in 1984. The program will eventually lead to the Earth Observing System (EOS) SAR later in this decade. SIR-C will provide increased capability over Seasat, SIR-A, and SIR-B by acquiring polarimetric images simultaneously at two microwave frequencies: L-band (wavelength 24 cm) and C-band (wavelength 6 cm). X-SAR will operate at X-band (wavelength 3 cm) with VV polarization, resulting in a three-frequency capability. Because radar backscatter is most strongly influenced by objects comparable in size to the radar wavelength, this multifrequency capability will provide information about the Earth's surface over a wide range of scales not discernable with single-frequency experiments. The polarimetric data will yield quantitative information about the surface geometric structure, vegetation dielectric properties, and surface discontinuities. The first SIR-C/X-SAR flight is planned for early in 1994, with two subsequent flights in different seasons to enable data aquisition under different environmental conditions. SIR-C/X-SAR will collect data for a period of 6 to 9 days during each flight. The instrument will be flown in a 57(deg) inclination orbit with a nomimal orbit altitude of 215 km. This altitude will result in a slightly drifting orbit. The latest status of the SIR-C/X-SAR mission and instrument design, science activities, and expected results will be presented.

  19. FlexSAR, a high quality, flexible, cost effective, prototype SAR system

    Science.gov (United States)

    Jensen, Mark; Knight, Chad; Haslem, Brent

    2016-05-01

    The FlexSAR radar system was designed to be a high quality, low-cost, flexible research prototype instrument. Radar researchers and practitioners often desire the ability to prototype new or advanced configurations, yet the ability to enhance or upgrade existing radar systems can be cost prohibitive. FlexSAR answers the need for a flexible radar system that can be extended easily, with minimal cost and time expenditures. The design approach focuses on reducing the resources required for developing and validating new advanced radar modalities. Such an approach fosters innovation and provides risk reduction since actual radar data can be collected in the appropriate mode, processed, and analyzed early in the development process. This allows for an accurate, detailed understanding of the corresponding trade space. This paper is a follow-on to last years paper and discusses the advancements that have been made to the FlexSAR system. The overall system architecture is discussed and presented along with several examples illustrating the system utility.

  20. Program Merges SAR Data on Terrain and Vegetation Heights

    Science.gov (United States)

    Siqueira, Paul; Hensley, Scott; Rodriguez, Ernesto; Simard, Marc

    2007-01-01

    X/P Merge is a computer program that estimates ground-surface elevations and vegetation heights from multiple sets of data acquired by the GeoSAR instrument [a terrain-mapping synthetic-aperture radar (SAR) system that operates in the X and bands]. X/P Merge software combines data from X- and P-band digital elevation models, SAR backscatter magnitudes, and interferometric correlation magnitudes into a simplified set of output topographical maps of ground-surface elevation and tree height.

  1. SAR antenna design for ambiguity and multipath suppression

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz; Dich, Mikael

    1993-01-01

    A high resolution airborne synthetic aperture radar (SAR) has been developed at the Electromagnetics Institute (EMI) for remote sensing applications. The paper considers the radiation of antennas for a SAR system from a systems perspective. The basic specifications of an idealised antenna...... are obtained from the required swath and the azimuth footprint needed for the SAR processing. The radiation from a real antenna causes unwanted signal returns that lead to intensity variations (multipath) and ghost echoes (ambiguity). Additional specifications are deduced by considering these signals...

  2. The Danish (Q)SAR Database Update Project

    DEFF Research Database (Denmark)

    Nikolov, Nikolai Georgiev; Dybdahl, Marianne; Abildgaard Rosenberg, Sine

    2013-01-01

    The Danish (Q)SAR Database is a collection of predictions from quantitative structure–activity relationship ((Q)SAR) models for over 70 environmental and human health-related endpoints (covering biodegradation, metabolism, allergy, irritation, endocrine disruption, teratogenicity, mutagenicity......, carcinogenicity and others), each of them available for 185,000 organic substances. The database has been available online since 2005 (http://qsar.food.dtu.dk). A major update project for the Danish (Q)SAR database is under way, with a new online release planned in the beginning of 2015. The updated version...

  3. SAR image effects on coherence and coherence estimation.

    Energy Technology Data Exchange (ETDEWEB)

    Bickel, Douglas Lloyd

    2014-01-01

    Radar coherence is an important concept for imaging radar systems such as synthetic aperture radar (SAR). This document quantifies some of the effects in SAR which modify the coherence. Although these effects can disrupt the coherence within a single SAR image, this report will focus on the coherence between separate images, such as for coherent change detection (CCD) processing. There have been other presentations on aspects of this material in the past. The intent of this report is to bring various issues that affect the coherence together in a single report to support radar engineers in making decisions about these matters.

  4. Mapping and monitoring renewable resources with space SAR

    Science.gov (United States)

    Ulaby, F. T.; Brisco, B.; Dobson, M. C.; Moezzi, S.

    1983-01-01

    The SEASAT-A SAR and SIR-A imagery was examined to evaluate the quality and type of information that can be extracted and used to monitor renewable resources on Earth. Two tasks were carried out: (1) a land cover classification study which utilized two sets of imagery acquired by the SEASAT-A SAR, one set by SIR-A, and one LANDSAT set (4 bands); and (2) a change detection to examine differences between pairs of SEASAT-A SAR images and relates them to hydrologic and/or agronomic variations in the scene.

  5. InSAR processing for the recognition of landslides

    Directory of Open Access Journals (Sweden)

    B. Riedel

    2008-01-01

    Full Text Available Synthetic Aperture Radar Interferometry (InSAR is an established method for the detection and monitoring of earth surface processes. This approach has been most successful where the observed area fulfills specific requirements, such as sufficient backscattering, flat slope gradients or very slow changes of vegetation. We investigated the capability of two different InSAR techniques and achieved good results for the recognition of landslides in China and Greece that compared well with geodetic derived movement rates. This demonstrates the strong potential of SAR Interferometry for the detection of landslides and earth surface movements.

  6. Problemas de salud pública causados por el SARS

    OpenAIRE

    Hao, Niu

    2014-01-01

    El síndrome respiratorio agudo severo (Severe Acute Respiratory Syndrome) es conocido como SARS. Los principales síntomas del SARS son fiebre alta (> 38ºC), tos, falta de aliento o dificultad para respirar. Puede estar acompañada de otros síntomas como dolor de cabeza, pérdida de apetito, rigidez muscular, trastorno de conciencia, fatiga, erupciones en la piel y diarrea, y en radiografías de tórax se pueden encontrar lesiones pulmonares. Cuando el SARS es más grave puede aparecer la neumon...

  7. Wind mapping offshore in coastal Mediterranean area using SAR images

    DEFF Research Database (Denmark)

    Calaudi, Rosamaria; Arena, Felice; Badger, Merete

    Satellite observations of the ocean surface from Synthetic Aperture Radars (SAR) provide information about the spatial wind variability over large areas. This is of special interest in the Mediterranean, where spatial wind information is only provided by sparse buoys, often with long periods...... of missing data. Here, we focus on evaluating the use of SAR for offshore wind mapping. Preliminary results from the analysis of SAR-based ocean winds in Mediterranean areas show interesting large scale wind flow features consistent with results from previous studies using numerical models and space borne...

  8. Obstacles and advances in SARS vaccine development.

    Science.gov (United States)

    Taylor, Deborah R

    2006-02-13

    The emergence of the severe acute respiratory syndrome (SARS) that resulted in a pandemic in 2003 spurred a flurry of interest in the development of vaccines to prevent and treat the potentially deadly viral infection. Researchers around the world pooled their scientific resources and shared early data in an unprecedented manner in light of the impending public health crisis. There are still large gaps in knowledge about the pathogenesis of this virus. While significant advances have been made in the development of animal models, the practicality of their use may be hampered by a lack of pathological similarity with human disease. Described here are issues related to progress in vaccine development and the obstacles that lie ahead for both researchers and regulatory agencies.

  9. SARS and the Academic Health Sector.

    Science.gov (United States)

    Gray, Jean

    2005-02-01

    SARS illustrated the vulnerability of the entire country to the importation of new organisms and other unexpected health crises. As the federal government assumes a leadership role in developing programs and policies affecting the security of Canada, so, too, should it assume a leadership role in public health matters, especially in an era of possible bioterrorism. The essential needs of such a system include: * A real-time inventory of research and response capacity to include the academic, industry, and government communities that could respond to a major health crisis in the future. * Research platforms in place across the country such as appropriately secure animal care facilities, biobanks, and other technologies necessary to immediately address research issues arising from such a crisis. * Coordinated processes to move appropriate people and resources into place when a health crisis requires such action. * Financial contingency funds that can be mobilized on relatively short notice to respond to the needs of altered patient care patterns and research.

  10. A NEW SAR CLASSIFICATION SCHEME FOR SEDIMENTS ON INTERTIDAL FLATS BASED ON MULTI-FREQUENCY POLARIMETRIC SAR IMAGERY

    Directory of Open Access Journals (Sweden)

    W. Wang

    2017-11-01

    Full Text Available We present a new classification scheme for muddy and sandy sediments on exposed intertidal flats, which is based on synthetic aperture radar (SAR data, and use ALOS-2 (L-band, Radarsat-2 (C-band and TerraSAR-X (X-band fully polarimetric SAR imagery to demonstrate its effectiveness. Four test sites on the German North Sea coast were chosen, which represent typical surface compositions of different sediments, vegetation, and habitats, and of which a large amount of SAR is used for our analyses. Both Freeman-Durden and Cloude-Pottier polarimetric decomposition are utilized, and an additional descriptor called Double-Bounce Eigenvalue Relative Difference (DERD is introduced into the feature sets instead of the original polarimetric intensity channels. The classification is conducted following Random Forest theory, and the results are verified using ground truth data from field campaigns and an existing classification based on optical imagery. In addition, the use of Kennaugh elements for classification purposes is demonstrated using both fully and dual-polarization multi-frequency and multi-temporal SAR data. Our results show that the proposed classification scheme can be applied for the discrimination of muddy and sandy sediments using L-, C-, and X-band SAR images, while SAR imagery acquired at short wavelengths (C- and X-band can also be used to detect more detailed features such as bivalve beds on intertidal flats.

  11. Deformation Monitoring of Urban Infrastructure by Tomographic SAR Using Multi-View TerraSAR-X Data Stacks

    Science.gov (United States)

    Montazeri, Sina; Zhu, Xiaoxiang; Eineder, Michael; Hanssen, Ramon F.; Bamler, Richard

    2015-05-01

    Synthetic Aperture Radar Tomography (TomoSAR) coupled with data from modern SAR sensors, such as the German TerraSAR-X (TS-X) produces the most detailed three-dimensional (3D) maps by distinguishing among multiple scatterers within a resolution cell. Furthermore, multi-temporal TomoSAR allows for recording the underlying deformation phenomenon of each individual scatterer. One of the limitations of using InSAR techniques, including TomoSAR, is that they only measure deformation along the radar Line-of-Sight (LOS). In order to enhance the understanding of deformation, a decomposition of the observed LOS displacement into the 3D deformation vector in the local coordinate system is desired. In this paper we propose a method, based on L1 norm minimization within local spatial cubes, to reconstruct 3D deformation vectors from TomoSAR point clouds available from, at least, three different viewing geometries. The methodology is applied on two pair of cross-heading TS-X spotlight image stacks over the city of Berlin. The linear deformation rate and amplitude of seasonal deformation are decomposed and the results from two individual test sites with remarkable deformation patterns are discussed in details.

  12. Radionuclide release calculations for SAR-08

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, Gavin; Miller, Alex; Smith, Graham; Jackson, Duncan (Enviros Consulting Ltd, Wolverhampton (United Kingdom))

    2008-04-15

    Following a review by the Swedish regulatory authorities of the post-closure safety assessment of the SFR 1 disposal facility for low and intermediate waste (L/ILW), SAFE, the SKB has prepared an updated assessment called SAR-08. This report describes the radionuclide release calculations that have been undertaken as part of SAR-08. The information, assumptions and data used in the calculations are reported and the results are presented. The calculations address issues raised in the regulatory review, but also take account of new information including revised inventory data. The scenarios considered include the main case of expected behaviour of the system, with variants; low probability releases, and so-called residual scenarios. Apart from these scenario uncertainties, data uncertainties have been examined using a probabilistic approach. Calculations have been made using the AMBER software. This allows all the component features of the assessment model to be included in one place. AMBER has been previously used to reproduce results the corresponding calculations in the SAFE assessment. It is also used in demonstration of the IAEA's near surface disposal assessment methodology ISAM and has been subject to very substantial verification tests and has been used in verifying other assessment codes. Results are presented as a function of time for the release of radionuclides from the near field, and then from the far field into the biosphere. Radiological impacts of the releases are reported elsewhere. Consideration is given to each radionuclide and to each component part of the repository. The releases from the entire repository are also presented. The peak releases rates are, for most scenarios, due to organic C-14. Other radionuclides which contribute to peak release rates include inorganic C-14, Ni-59 and Ni-63. (author)

  13. (Non-) homomorphic approaches to denoise intensity SAR images with non-local means and stochastic distances

    Science.gov (United States)

    Penna, Pedro A. A.; Mascarenhas, Nelson D. A.

    2018-02-01

    The development of new methods to denoise images still attract researchers, who seek to combat the noise with the minimal loss of resolution and details, like edges and fine structures. Many algorithms have the goal to remove additive white Gaussian noise (AWGN). However, it is not the only type of noise which interferes in the analysis and interpretation of images. Therefore, it is extremely important to expand the filters capacity to different noise models present in li-terature, for example the multiplicative noise called speckle that is present in synthetic aperture radar (SAR) images. The state-of-the-art algorithms in remote sensing area work with similarity between patches. This paper aims to develop two approaches using the non local means (NLM), developed for AWGN. In our research, we expanded its capacity for intensity SAR ima-ges speckle. The first approach is grounded on the use of stochastic distances based on the G0 distribution without transforming the data to the logarithm domain, like homomorphic transformation. It takes into account the speckle and backscatter to estimate the parameters necessary to compute the stochastic distances on NLM. The second method uses a priori NLM denoising with a homomorphic transformation and applies the inverse Gamma distribution to estimate the parameters that were used into NLM with stochastic distances. The latter method also presents a new alternative to compute the parameters for the G0 distribution. Finally, this work compares and analyzes the synthetic and real results of the proposed methods with some recent filters of the literature.

  14. ISCE: A Modular, Reusable Library for Scalable SAR/InSAR Processing

    Science.gov (United States)

    Agram, P. S.; Lavalle, M.; Gurrola, E. M.; Sacco, G. F.; Rosen, P. A.

    2016-12-01

    Traditional community SAR/InSAR processing software tools have primarily focused on differential interferometry and Solid Earth applications. The InSAR Scientific Computing Environment (ISCE) was specifically designed to support the Earth Sciences user community as well as large scale operational processing tasks, thanks to its two-layered (Python+C/Fortran) architecture and modular framework. ISCE is freely distributed as a source tarball, allowing advanced users to modify and extend it for their research purposes and developing exploratory applications, while providing a relatively simple user interface for novice users to perform routine data analysis efficiently. Modular design of the ISCE library also enables easier development of applications to address the needs of Ecosystems, Cryosphere and Disaster Response communities in addition to the traditional Solid Earth applications. In this talk, we would like to emphasize the broader purview of the ISCE library and some of its unique features that sets it apart from other freely available community software like GMTSAR and DORIS, including: Support for multiple geometry regimes - Native Doppler (ALOS-1) as well Zero Doppler (ESA missions) systems. Support for data acquired by airborne platforms - e.g, JPL's UAVSAR and AirMOSS, DLR's F-SAR. Radiometric Terrain Correction - Auxiliary output layers from the geometry modules include projection angles, incidence angles, shadow-layover masks. Dense pixel offsets - Parallelized amplitude cross correlation for cryosphere / ionospheric correction applications. Rubber sheeting - Pixel-by-pixel offsets fields for resampling slave imagery for geometric co-registration/ ionospheric corrections. Preliminary Tandem-X processing support - Bistatic geometry modules. Extensibility to support other non-Solid Earth missions - Modules can be directly adopted for use with other SAR missions, e.g., SWOT. Preliminary support for multi-dimensional data products- multi-polarization, multi

  15. Hydrodynamics of the groundwater-fed Sian Ka'an Wetlands, Mexico, From InSAR and SAR Data

    DEFF Research Database (Denmark)

    Gondwe, Bibi Ruth Neuman; Hong, S.; Wdowinski, S.

    2008-01-01

    -changes of the backscattered radar signal, which can be related to the water level changes in vegetated wetlands. SAR data reveals information of surface properties such as the degree of flooding through the amplitude of the backscattered signal. We used RADARSAT-1 InSAR and SAR data to form 36 interferograms and 13 flooding...... well with tidal predictions. The interferograms also reveal information about surface water flow directions and local-scale flow divides in the wetland, which are important for understanding the wetland hydrology. These flow directions and divides are supported by structures visible on Landsat imagery...... hydrological modelling of the wetland....

  16. Choosing and using astronomical filters

    CERN Document Server

    Griffiths, Martin

    2014-01-01

    As a casual read through any of the major amateur astronomical magazines will demonstrate, there are filters available for all aspects of optical astronomy. This book provides a ready resource on the use of the following filters, among others, for observational astronomy or for imaging: Light pollution filters Planetary filters Solar filters Neutral density filters for Moon observation Deep-sky filters, for such objects as galaxies, nebulae and more Deep-sky objects can be imaged in much greater detail than was possible many years ago. Amateur astronomers can take

  17. Filters for cathodic arc plasmas

    Science.gov (United States)

    Anders, Andre; MacGill, Robert A.; Bilek, Marcela M. M.; Brown, Ian G.

    2002-01-01

    Cathodic arc plasmas are contaminated with macroparticles. A variety of magnetic plasma filters has been used with various success in removing the macroparticles from the plasma. An open-architecture, bent solenoid filter, with additional field coils at the filter entrance and exit, improves macroparticle filtering. In particular, a double-bent filter that is twisted out of plane forms a very compact and efficient filter. The coil turns further have a flat cross-section to promote macroparticle reflection out of the filter volume. An output conditioning system formed of an expander coil, a straightener coil, and a homogenizer, may be used with the magnetic filter for expanding the filtered plasma beam to cover a larger area of the target. A cathodic arc plasma deposition system using this filter can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  18. Sensory pollution from bag filters, carbon filters and combinations.

    Science.gov (United States)

    Bekö, G; Clausen, G; Weschler, C J

    2008-02-01

    Used ventilation filters are a major source of sensory pollutants in air handling systems. The objective of the present study was to evaluate the net effect that different combinations of filters had on perceived air quality after 5 months of continuous filtration of outdoor suburban air. A panel of 32 subjects assessed different sets of used filters and identical sets consisting of new filters. Additionally, filter weights and pressure drops were measured at the beginning and end of the operation period. The filter sets included single EU5 and EU7 fiberglass filters, an EU7 filter protected by an upstream pre-filter (changed monthly), an EU7 filter protected by an upstream activated carbon (AC) filter, and EU7 filters with an AC filter either downstream or both upstream and downstream. In addition, two types of stand-alone combination filters were evaluated: a bag-type fiberglass filter that contained AC and a synthetic fiber cartridge filter that contained AC. Air that had passed through used filters was most acceptable for those sets in which an AC filter was used downstream of the particle filter. Comparable air quality was achieved with the stand-alone bag filter that contained AC. Furthermore, its pressure drop changed very little during the 5 months of service, and it had the added benefit of removing a large fraction of ozone from the airstream. If similar results are obtained over a wider variety of soiling conditions, such filters may be a viable solution to a long recognized problem. The present study was designed to address the emission of sensory offending pollutants from loaded ventilation filters. The goal was to find a low-polluting solution from commercially available products. The results indicate that the use of activated carbon (AC) filters downstream of fiberglass bag filters can reduce the degradation of air quality that occurs with increasing particle loading. A more practical solution, yet comparably effective, is a stand-alone particle

  19. Multilevel ensemble Kalman filtering

    KAUST Repository

    Hoel, Haakon

    2016-01-08

    The ensemble Kalman filter (EnKF) is a sequential filtering method that uses an ensemble of particle paths to estimate the means and covariances required by the Kalman filter by the use of sample moments, i.e., the Monte Carlo method. EnKF is often both robust and efficient, but its performance may suffer in settings where the computational cost of accurate simulations of particles is high. The multilevel Monte Carlo method (MLMC) is an extension of classical Monte Carlo methods which by sampling stochastic realizations on a hierarchy of resolutions may reduce the computational cost of moment approximations by orders of magnitude. In this work we have combined the ideas of MLMC and EnKF to construct the multilevel ensemble Kalman filter (MLEnKF) for the setting of finite dimensional state and observation spaces. The main ideas of this method is to compute particle paths on a hierarchy of resolutions and to apply multilevel estimators on the ensemble hierarchy of particles to compute Kalman filter means and covariances. Theoretical results and a numerical study of the performance gains of MLEnKF over EnKF will be presented. Some ideas on the extension of MLEnKF to settings with infinite dimensional state spaces will also be presented.

  20. Multilevel Mixture Kalman Filter

    Directory of Open Access Journals (Sweden)

    Xiaodong Wang

    2004-11-01

    Full Text Available The mixture Kalman filter is a general sequential Monte Carlo technique for conditional linear dynamic systems. It generates samples of some indicator variables recursively based on sequential importance sampling (SIS and integrates out the linear and Gaussian state variables conditioned on these indicators. Due to the marginalization process, the complexity of the mixture Kalman filter is quite high if the dimension of the indicator sampling space is high. In this paper, we address this difficulty by developing a new Monte Carlo sampling scheme, namely, the multilevel mixture Kalman filter. The basic idea is to make use of the multilevel or hierarchical structure of the space from which the indicator variables take values. That is, we draw samples in a multilevel fashion, beginning with sampling from the highest-level sampling space and then draw samples from the associate subspace of the newly drawn samples in a lower-level sampling space, until reaching the desired sampling space. Such a multilevel sampling scheme can be used in conjunction with the delayed estimation method, such as the delayed-sample method, resulting in delayed multilevel mixture Kalman filter. Examples in wireless communication, specifically the coherent and noncoherent 16-QAM over flat-fading channels, are provided to demonstrate the performance of the proposed multilevel mixture Kalman filter.

  1. A new approach for improving flood model predictions based on the sequential assimilation of SAR-derived flood extent maps

    Science.gov (United States)

    Hostache, Renaud; Corato, Giovanni; Chini, Marco; Wood, Melissa; Giustarini, Laura; Matgen, Patrick

    2015-04-01

    Hydrodynamic models represent an important component in flood prediction systems. However, providing reliable model predictions and reducing the associated uncertainties remain challenging, especially in poorly gauged river basins. As Synthetic Aperture Radar-derived flood image databases are significant (and expected to grow rapidly with contributions from new satellites such as Sentinel-1) there are emerging opportunities for using these data collections to improve model predictions. In this context our aim is to contribute to the development of a global and near real-time remote sensing-based service that delivers flood predictions to support flood management. The study takes advantage of recently developed efficient, rapid and automatic algorithms for the delineation of flood extent using SAR images. The main objective of the study is to show how near real-time sequential assimilation of SAR derived flood extents can improve model predictions. As a test case we use the July 2007 flood event of the river Severn (UK) and the February 2007 flood event of the lower Zambezi (Mozambique). We use the Lisflood-FP hydraulic model and we adopt a particle filter-based assimilation scheme. An important issue in the framework of the assimilation of remote sensing-derived information is to quantify observation uncertainty. To do so we introduce for the first time an image processing approach that assigns to each pixel a 'probability to be flooded' based on its backscatter values. The sequential assimilation of SAR-derived flood extent maps shows a significant improvement in the hydraulic model predictions. The main achievement of the study is that model predictions are clearly improved by the assimilation of SAR-derived flood extent not only in terms of predicted flooded areas but also in terms of predicted discharge and water level surface elevation hydrographs.

  2. Seeing the unseen: Complete volcano deformation fields by recursive filtering of satellite radar interferograms

    Science.gov (United States)

    Gonzalez, Pablo J.

    2017-04-01

    Automatic interferometric processing of satellite radar data has emerged as a solution to the increasing amount of acquired SAR data. Automatic SAR and InSAR processing ranges from focusing raw echoes to the computation of displacement time series using large stacks of co-registered radar images. However, this type of interferometric processing approach demands the pre-described or adaptive selection of multiple processing parameters. One of the interferometric processing steps that much strongly influences the final results (displacement maps) is the interferometric phase filtering. There are a large number of phase filtering methods, however the "so-called" Goldstein filtering method is the most popular [Goldstein and Werner, 1998; Baran et al., 2003]. The Goldstein filter needs basically two parameters, the size of the window filter and a parameter to indicate the filter smoothing intensity. The modified Goldstein method removes the need to select the smoothing parameter based on the local interferometric coherence level, but still requires to specify the dimension of the filtering window. An optimal filtered phase quality usually requires careful selection of those parameters. Therefore, there is an strong need to develop automatic filtering methods to adapt for automatic processing, while maximizing filtered phase quality. Here, in this paper, I present a recursive adaptive phase filtering algorithm for accurate estimation of differential interferometric ground deformation and local coherence measurements. The proposed filter is based upon the modified Goldstein filter [Baran et al., 2003]. This filtering method improves the quality of the interferograms by performing a recursive iteration using variable (cascade) kernel sizes, and improving the coherence estimation by locally defringing the interferometric phase. The method has been tested using simulations and real cases relevant to the characteristics of the Sentinel-1 mission. Here, I present real examples

  3. RAMP AMM-1 SAR Image Mosaic of Antarctica

    Data.gov (United States)

    National Aeronautics and Space Administration — In 1997, the Canadian RADARSAT-1 satellite was rotated in orbit so that its Synthetic Aperture Radar (SAR) antenna looked south towards Antarctica. This permitted...

  4. Modeling of SAR signatures of shallow water ocean topography

    Science.gov (United States)

    Shuchman, R. A.; Kozma, A.; Kasischke, E. S.; Lyzenga, D. R.

    1984-01-01

    A hydrodynamic/electromagnetic model was developed to explain and quantify the relationship between the SEASAT synthetic aperture radar (SAR) observed signatures and the bottom topography of the ocean in the English Channel region of the North Sea. The model uses environmental data and radar system parameters as inputs and predicts SAR-observed backscatter changes over topographic changes in the ocean floor. The model results compare favorably with the actual SEASAT SAR observed backscatter values. The developed model is valid for only relatively shallow water areas (i.e., less than 50 meters in depth) and suggests that for bottom features to be visible on SAR imagery, a moderate to high velocity current and a moderate wind must be present.

  5. An Efficient Algorithm to Processing SAR Data on GPU

    Directory of Open Access Journals (Sweden)

    Meng Da-di

    2013-06-01

    Full Text Available Data processing is a time-consuming matter in the field of Synthetic Aperture Radar (SAR. In other ways, Graphic Processing Unit (GPU have tremendous float-point computational horsepower and very high memory bandwidth, and the developing Compute Unified Device Architecture (CUDA technology has enabled the GPU to be applied to the general purpose parallel computing. A new method of processing SAR data on GPU is presented in this paper. Compared with the nominal GPU based SAR processing method, number of data transfers between CPU/GPU are reduced from 4 to 1, and CPUs are exploited to cooperate with GPU synchronously. By the proposed method, data Processing is speeded up by 2.3 times, which is verified by the testing on the simulated SAR data.

  6. Alaska Satellite Facility ASF5 SAR Data Processing System Overview

    Science.gov (United States)

    Leung, K.; Cuddy, D.; Chen, M.

    1994-01-01

    The Alaska SAR Facility (ASF) situated at the University of Alaska Fairbanks (UAF) is currently undergoing an extensive development effort to increase its capabilities in handling new sensors and in the areas of throughput, data handling, archive, and distribution [15].

  7. Investigation on Fine Registration for SAR and Optical Image

    Directory of Open Access Journals (Sweden)

    You Hong-jian

    2014-02-01

    Full Text Available The registration of SAR and optical remote sensing image is the basise for fusing of multi-source image and comprehensive analysis. In this paper a new fine registration method for SAR and optical image is proposed. Firstly, three to four corresponding points are selected manually to realize a coarse registration that eliminates the differences in scale and rotation. Many characteristic points in the optical image are detected and the corresponding points in SAR image are extracted using normalized gradient correlations based on the different gradients by operators. An irregular triangle network is constructed using these corresponding points and each triangle region is finely registered. Finally SAR image and optical image are finely registered. Experiment and processed results demonstrate the feasibility of this method.

  8. Infrastructure stability surveillance with high resolution InSAR

    Science.gov (United States)

    Balz, Timo; Düring, Ralf

    2017-02-01

    The construction of new infrastructure in largely unknown and difficult environments, as it is necessary for the construction of the New Silk Road, can lead to a decreased stability along the construction site, leading to an increase in landslide risk and deformation caused by surface motion. This generally requires a thorough pre-analysis and consecutive surveillance of the deformation patterns to ensure the stability and safety of the infrastructure projects. Interferometric SAR (InSAR) and the derived techniques of multi-baseline InSAR are very powerful tools for a large area observation of surface deformation patterns. With InSAR and deriver techniques, the topographic height and the surface motion can be estimated for large areas, making it an ideal tool for supporting the planning, construction, and safety surveillance of new infrastructure elements in remote areas.

  9. Stellwagen Bank National Marine Sanctuary - Synthetic Aperture Radar (SAR) Imagery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This geodatabase contains Synthetic Aperture Radar images (SAR), which consist of a fine resolution (12.5-50m), two-dimensional radar backscatter map of the...

  10. Change detection in polarimetric SAR data over several time points

    DEFF Research Database (Denmark)

    Conradsen, Knut; Nielsen, Allan Aasbjerg; Skriver, Henning

    2014-01-01

    A test statistic for the equality of several variance-covariance matrices following the complex Wishart distribution is introduced. The test statistic is applied successfully to detect change in C-band EMISAR polarimetric SAR data over four time points....

  11. A Stepped Frequency CW SAR for Lightweight UAV Operation

    National Research Council Canada - National Science Library

    Morrison, Keith

    2005-01-01

    A stepped-frequency continuous wave (SF-CW) synthetic aperture radar (SAR), with frequency-agile waveforms and real-time intelligent signal processing algorithms, is proposed for operation from a lightweight UAV platform...

  12. Segment-based change detection for polarimetric SAR data

    DEFF Research Database (Denmark)

    Skriver, Henning; Nielsen, Allan Aasbjerg; Conradsen, Knut

    2006-01-01

    polarimetric synthetic aperture radar (SAR) backscatter data is the so-called covariance matrix data format. For each pixel this consists of a 3×3 Hermitian, positive definite matrix which follows a complex Wishart distribution. Based on this distribution a test statistic for equality of two such matrices....... This method relies primarily on a robust edge detector, which preferably provides a constant false alarm rate. For single-channel SAR images this is fulfilled by the ratio edge detector, and for polarimetric SAR data, an edge detector based on the above mentioned test statistic fulfils this. Another approach...... criterion is based on the Wishart test statistic for fully polarimetric SAR data. 2. METHODOLOGY In change detection applications, at least two images must be available and used in the change detection process. If these images are segmented independently, the segments in the different images will most...

  13. A comparative study of SAR data compression schemes

    Science.gov (United States)

    Lambert-Nebout, C.; Besson, O.; Massonnet, D.; Rogron, B.

    1994-01-01

    The amount of data collected from spaceborne remote sensing has substantially increased in the last years. During same time period, the ability to store or transmit data has not increased as quickly. At this time, there is a growing interest in developing compression schemes that could provide both higher compression ratios and lower encoding/decoding errors. In the case of the spaceborne Synthetic Aperture Radar (SAR) earth observation system developed by the French Space Agency (CNES), the volume of data to be processed will exceed both the on-board storage capacities and the telecommunication link. The objective of this paper is twofold: to present various compression schemes adapted to SAR data; and to define a set of evaluation criteria and compare the algorithms on SAR data. In this paper, we review two classical methods of SAR data compression and propose novel approaches based on Fourier Transforms and spectrum coding.

  14. Massachusetts Bay - Internal wave packets digitized from SAR imagery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery at 1:350,000 scale in Massachusetts Bay. Internal waves are nonsinusoidal waves that...

  15. Mining Land Subsidence Monitoring Using SENTINEL-1 SAR Data

    Science.gov (United States)

    Yuan, W.; Wang, Q.; Fan, J.; Li, H.

    2017-09-01

    In this paper, DInSAR technique was used to monitor land subsidence in mining area. The study area was selected in the coal mine area located in Yuanbaoshan District, Chifeng City, and Sentinel-1 data were used to carry out DInSAR techniqu. We analyzed the interferometric results by Sentinel-1 data from December 2015 to May 2016. Through the comparison of the results of DInSAR technique and the location of the mine on the optical images, it is shown that DInSAR technique can be used to effectively monitor the land subsidence caused by underground mining, and it is an effective tool for law enforcement of over-mining.

  16. An Improved GLRT Method for Target Detection in SAR Imagery

    Directory of Open Access Journals (Sweden)

    Ju Yingyun

    2015-01-01

    Full Text Available Automatic ground vehicle detection based on SAR imagery is one of the important military applications of SAR. A region-based generalized likelihood ratio test (GLRT method is proposed in this paper, and this method combines the GLRT detection theory and image segmentation technology. First, the SAR imagery is roughly segmented as land clutter region and potential target region through the split and merge procedure often used for processing the original images. Then, based on the segmentation results, the reasonable statistical models for the data in the two regions are built respectively. Finally, with the knowledge of statistical characteristics of clutter and target, GLRT detection method is applied to the each pixel in the potential target region to obtain more accurate detection results. Experimental results based on real SAR data show that the proposed method can effectively detect the ground vehicle targets from the land clutter with excellent accuracy and speed.

  17. Filters for Submillimeter Electromagnetic Waves

    Science.gov (United States)

    Berdahl, C. M.

    1986-01-01

    New manufacturing process produces filters strong, yet have small, precise dimensions and smooth surface finish essential for dichroic filtering at submillimeter wavelengths. Many filters, each one essentially wafer containing fine metal grid made at same time. Stacked square wires plated, fused, and etched to form arrays of holes. Grid of nickel and tin held in brass ring. Wall thickness, thickness of filter (hole depth) and lateral hole dimensions all depend upon operating frequency and filter characteristics.

  18. The Staphylococcus aureus protein-coding gene gdpS modulates sarS expression via mRNA-mRNA interaction.

    Science.gov (United States)

    Chen, Chuan; Zhang, Xu; Shang, Fei; Sun, Haipeng; Sun, Baolin; Xue, Ting

    2015-08-01

    Staphylococcus aureus is an important Gram-positive pathogen responsible for numerous diseases ranging from localized skin infections to life-threatening systemic infections. The virulence of S. aureus is essentially determined by a wide spectrum of factors, including cell wall-associated proteins and secreted toxins that are precisely controlled in response to environmental changes. GGDEF domain protein from Staphylococcus (GdpS) is the only conserved staphylococcal GGDEF domain protein that is involved not in c-di-GMP synthesis but in the virulence regulation of S. aureus NCTC8325. Our previous study showed that the inactivation of gdpS generates an extensive change of virulence factors together with, in particular, a major Spa (protein A) surface protein. As reported, sarS is a direct positive regulator of spa. The decreased transcript levels of sarS in the gdpS mutant compared with the parental NCTC8325 strain suggest that gdpS affects spa through interaction with sarS. In this study, site mutation and complementary experiments showed that the translation product of gdpS was not involved in the regulation of transcript levels of sarS. We found that gdpS functioned through direct RNA-RNA base pairing with the 5' untranslated region (5'UTR) of sarS mRNA and that a putative 18-nucleotide region played a significant role in the regulatory process. Furthermore, the mRNA half-life analysis of sarS in the gdpS mutant showed that gdpS positively regulates the mRNA levels of sarS by contributing to the stabilization of sarS mRNA, suggesting that gdpS mRNA may regulate spa expression in an RNA-dependent pathway. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  19. Concept of an Effective Sentinel-1 Satellite SAR Interferometry System

    OpenAIRE

    Lazecky, Milan; Comut, Fatma Canaslan; Bakon, Matus; Qin, Yuxiao; Perissin, Daniele; Hatton, Emma; Spaans, Karsten; Mendez, Pablo J. Gonzalez; Guimaraes, Pedro; de Sousa, Joaquim J.M.; Kocich, David; Ustun, Aydin

    2016-01-01

    This brief study introduces a partially working concept being developed at IT4Innovations supercomputer (HPC) facility. This concept consists of several modules that form a whole body of an efficient system for observation of terrain or objects displacements using satellite SAR interferometry (InSAR). A metadata database helps to locate data stored in various storages and to perform basic analyzes. A special database has been designed to describe Sentinel-1 data, on its burst level. Custom Se...

  20. Statistical SAR studies of windfields near Unimak Island

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.B.; Pan, F. [Yale Univ., New Haven, CT (United States)

    1997-06-01

    The modification of wind patterns by coastlines and islands is outlined. The paper focuses on methods for observing the sheltering effect, in which windspeed downwind of high terrain is reduced. Three observational methods are described: in situ observation, sunglint imagery using specular reflection, and synthetic-aperture radar (SAR). A data archive of SAR images of Unimak Island in the Aleutian Islands chain which was analyzed for sheltering effects is described.

  1. CV-990 L-band SAR: A calibration experiment

    Science.gov (United States)

    Held, D. N.; Werner, C.

    1985-01-01

    Calibrated image data is required by most users of synthetic aperture radar (SAR) data particularly those attempting to classify targets based upon their radar backscatter signature as a function of frequency polarization or incidence angle. In this experiment, the backscatter derived by calibrating the NASA/JPL CV-990 L-band SAR, and the backscatter reported from a pass of the NASA/JSC C-130 scatterometer as the two instruments flew over the same site at different times are compared.

  2. Focusing SAR data acquired from non-linear sensor trajectories

    OpenAIRE

    Frey, O.; Magnard, C; RÜEGG, M.; Meier, E.

    2008-01-01

    Standard focusing of SAR data assumes a straight recording track of the sensor platform. Small non-linearities of airborne platform tracks are corrected for during a motion compensation step while keeping the assumption of a linear flight path. In the following, the processing of SAR data from nonlinear tracks is discussed as may originate from small aircraft or drones flying at low altitude. They fly not a straight track but one dependent on topography, influences of weather and wind, or ...

  3. Using airborne and satellite SAR for wake mapping offshore

    Science.gov (United States)

    Christiansen, Merete B.; Hasager, Charlotte B.

    2006-09-01

    Offshore wind energy is progressing rapidly around Europe. One of the latest initiatives is the installation of multiple wind farms in clusters to share cables and maintenance costs and to fully exploit premium wind resource sites. For siting of multiple nearby wind farms, the wind turbine wake effect must be considered. Synthetic aperture radar (SAR) is an imaging remote sensing technique which offers a unique opportunity to describe spatial variations of wind speed offshore. For the first time an airborne SAR instrument was used for data acquisition over a large offshore wind farm. The aim was to identify the turbine wake effect from SAR-derived wind speed maps as a downstream region of reduced wind speed. The aircraft SAR campaign was conducted on 12 October 2003 over the wind farm at Horns Rev in the North Sea. Nearly simultaneous measurements were acquired over the area by the SAR on board the ERS-2 satellite. In addition, meteorological data were collected. Both aircraft and satellite SAR-derived wind speed maps showed significant velocity deficits downstream of the wind farm. Wind speed maps retrieved from aircraft SAR suggested deficits of up to 20% downstream of the last turbine, whereas satellite SAR-derived maps showed deficits of the order of 10%. The difference originated partly from the two different reference methods used for normalization of measured wind speeds. The detected region of reduced wind speed had the same width as the wind turbine array, indicating a low degree of horizontal wake dispersion. The downstream wake extent was approximately 10 km, which corresponds well with results from previous studies and with wake model predictions. Copyright

  4. sar vallejo's poetry: the paradigm of the rebellion

    OpenAIRE

    Lipnevičiūtė, Rolanda

    2016-01-01

    "César Vallejo's Poetry: the Paradigm of the Rebellion". The object of bachelor work „ César Vallejo' Poetry: the Paradigm of the Rebellion “ is the poetry of Peruvian poet Cesar Vallejo. The study aims to reveal the paradigm of the rebellion that was observed in three following aspects: the social rebellion, internal oppositions and arguments with the Bible. In order to conduct a survey the hermeneutic poetry analysis and sociocultural perspectives were used. According to the hypothesis form...

  5. Evolution and Variation of the SARS-CoV Genome

    OpenAIRE

    Hu, Jianfei; Wang, Jing; Xu, Jing; Li, Wei; Han, Yujun; Li, Yan; Ji, Jia; Ye, Jia; Xu, Zhao; Zhang, Zizhang; Wei, Wei; Li, Songgang; Wang, Jun; Wang, Jian; Yu, Jun

    2016-01-01

    Knowledge of the evolution of pathogens is of great medical and biological significance to the prevention, diagnosis, and therapy of infectious diseases. In order to understand the origin and evolution of the SARS-CoV (severe acute respiratory syndrome-associated coronavirus), we collected complete genome sequences of all viruses available in GenBank, and made comparative analyses with the SARS-CoV. Genomic signature analysis demonstrates that the coronaviruses all take the TGTT as their rich...

  6. Adaptive digital filters

    CERN Document Server

    Kovačević, Branko; Milosavljević, Milan

    2013-01-01

    “Adaptive Digital Filters” presents an important discipline applied to the domain of speech processing. The book first makes the reader acquainted with the basic terms of filtering and adaptive filtering, before introducing the field of advanced modern algorithms, some of which are contributed by the authors themselves. Working in the field of adaptive signal processing requires the use of complex mathematical tools. The book offers a detailed presentation of the mathematical models that is clear and consistent, an approach that allows everyone with a college level of mathematics knowledge to successfully follow the mathematical derivations and descriptions of algorithms.   The algorithms are presented in flow charts, which facilitates their practical implementation. The book presents many experimental results and treats the aspects of practical application of adaptive filtering in real systems, making it a valuable resource for both undergraduate and graduate students, and for all others interested in m...

  7. Stack filter classifiers

    Energy Technology Data Exchange (ETDEWEB)

    Porter, Reid B [Los Alamos National Laboratory; Hush, Don [Los Alamos National Laboratory

    2009-01-01

    Just as linear models generalize the sample mean and weighted average, weighted order statistic models generalize the sample median and weighted median. This analogy can be continued informally to generalized additive modeels in the case of the mean, and Stack Filters in the case of the median. Both of these model classes have been extensively studied for signal and image processing but it is surprising to find that for pattern classification, their treatment has been significantly one sided. Generalized additive models are now a major tool in pattern classification and many different learning algorithms have been developed to fit model parameters to finite data. However Stack Filters remain largely confined to signal and image processing and learning algorithms for classification are yet to be seen. This paper is a step towards Stack Filter Classifiers and it shows that the approach is interesting from both a theoretical and a practical perspective.

  8. Automated electronic filter design

    CERN Document Server

    Banerjee, Amal

    2017-01-01

    This book describes a novel, efficient and powerful scheme for designing and evaluating the performance characteristics of any electronic filter designed with predefined specifications. The author explains techniques that enable readers to eliminate complicated manual, and thus error-prone and time-consuming, steps of traditional design techniques. The presentation includes demonstration of efficient automation, using an ANSI C language program, which accepts any filter design specification (e.g. Chebyschev low-pass filter, cut-off frequency, pass-band ripple etc.) as input and generates as output a SPICE(Simulation Program with Integrated Circuit Emphasis) format netlist. Readers then can use this netlist to run simulations with any version of the popular SPICE simulator, increasing accuracy of the final results, without violating any of the key principles of the traditional design scheme.

  9. Improved SAR Image Coregistration Using Pixel-Offset Series

    KAUST Repository

    Wang, Teng

    2014-03-14

    Synthetic aperture radar (SAR) image coregistration is a key procedure before interferometric SAR (InSAR) time-series analysis can be started. However, many geophysical data sets suffer from severe decorrelation problems due to a variety of reasons, making precise coregistration a nontrivial task. Here, we present a new strategy that uses a pixel-offset series of detected subimage patches dominated by point-like targets (PTs) to improve SAR image coregistrations. First, all potentially coherent image pairs are coregistered in a conventional way. In this step, we propose a coregistration quality index for each image to rank its relative “significance” within the data set and to select a reference image for the SAR data set. Then, a pixel-offset series of detected PTs is made from amplitude maps to improve the geometrical mapping functions. Finally, all images are resampled depending on the pixel offsets calculated from the updated geometrical mapping functions. We used images from a rural region near the North Anatolian Fault in eastern Turkey to test the proposed method, and clear coregistration improvements were found based on amplitude stability. This enhanced the fact that the coregistration strategy should therefore lead to improved InSAR time-series analysis results.

  10. Evaluation of Polarimetric SAR Decomposition for Classifying Wetland Vegetation Types

    Directory of Open Access Journals (Sweden)

    Sang-Hoon Hong

    2015-07-01

    Full Text Available The Florida Everglades is the largest subtropical wetland system in the United States and, as with subtropical and tropical wetlands elsewhere, has been threatened by severe environmental stresses. It is very important to monitor such wetlands to inform management on the status of these fragile ecosystems. This study aims to examine the applicability of TerraSAR-X quadruple polarimetric (quad-pol synthetic aperture radar (PolSAR data for classifying wetland vegetation in the Everglades. We processed quad-pol data using the Hong & Wdowinski four-component decomposition, which accounts for double bounce scattering in the cross-polarization signal. The calculated decomposition images consist of four scattering mechanisms (single, co- and cross-pol double, and volume scattering. We applied an object-oriented image analysis approach to classify vegetation types with the decomposition results. We also used a high-resolution multispectral optical RapidEye image to compare statistics and classification results with Synthetic Aperture Radar (SAR observations. The calculated classification accuracy was higher than 85%, suggesting that the TerraSAR-X quad-pol SAR signal had a high potential for distinguishing different vegetation types. Scattering components from SAR acquisition were particularly advantageous for classifying mangroves along tidal channels. We conclude that the typical scattering behaviors from model-based decomposition are useful for discriminating among different wetland vegetation types.

  11. DInSAR fringes simulation of sandbox models

    Science.gov (United States)

    Derron, Marc-Henri; Carrea, Dario; Michoud, Clément; Jaboyedoff, Michel

    2015-04-01

    Interpreting satellite DInSAR patterns of slope movements can be difficult because of unwrapping problems, loss of coherence or radar imaging geometry limitations (layover, shadowing …). We investigate the potential of simulating interferometric fringes as a tool to help understanding real DInSAR images. Various types of gravitational slope deformations (sliding, toppling …) have been produced in a sandbox in the lab. These experiments were monitored with a micro-lidar Minolta-Konika Vivid 9i to get successive Digital Elevation Models of the surface. A pair of DEM is then used to simulate DInSAR fringes patterns, with the possibility to vary the wavelength, the angle between the line of sight and the ground displacement, the look angle, the baseline, etc. DInSAR fringes simulated here are idealized. They are not affected by any noise, decoherence, layover or shadow effects; radar image deformations are computed in ancillary files. However it appears that even these ideal wrapped fringes patterns get rapidly very complex when deformation is strong. Then this kind of tool is of interest to better constrain ground surface deformations from resulting InSAR fringes (from lab models or real landslides data). It makes also possible to test how the acquisition geometry impacts the InSAR result depending on the type of slope movement considered.

  12. Urban Modelling Performance of Next Generation SAR Missions

    Science.gov (United States)

    Sefercik, U. G.; Yastikli, N.; Atalay, C.

    2017-09-01

    In synthetic aperture radar (SAR) technology, urban mapping and modelling have become possible with revolutionary missions TerraSAR-X (TSX) and Cosmo-SkyMed (CSK) since 2007. These satellites offer 1m spatial resolution in high-resolution spotlight imaging mode and capable for high quality digital surface model (DSM) acquisition for urban areas utilizing interferometric SAR (InSAR) technology. With the advantage of independent generation from seasonal weather conditions, TSX and CSK DSMs are much in demand by scientific users. The performance of SAR DSMs is influenced by the distortions such as layover, foreshortening, shadow and double-bounce depend up on imaging geometry. In this study, the potential of DSMs derived from convenient 1m high-resolution spotlight (HS) InSAR pairs of CSK and TSX is validated by model-to-model absolute and relative accuracy estimations in an urban area. For the verification, an airborne laser scanning (ALS) DSM of the study area was used as the reference model. Results demonstrated that TSX and CSK urban DSMs are compatible in open, built-up and forest land forms with the absolute accuracy of 8-10 m. The relative accuracies based on the coherence of neighbouring pixels are superior to absolute accuracies both for CSK and TSX.

  13. SAR11 Bacteria: The Most Abundant Plankton in the Oceans

    Science.gov (United States)

    Giovannoni, Stephen J.

    2017-01-01

    SAR11 is a group of small, carbon-oxidizing bacteria that reach a global estimated population size of 2.4×1028 cells—approximately 25% of all plankton. They are found throughout the oceans but reach their largest numbers in stratified, oligotrophic gyres, which are an expanding habitat in the warming oceans. SAR11 likely had a Precambrian origin and, over geological time, evolved into the niche of harvesting labile, low-molecular-weight dissolved organic matter (DOM). SAR11 cells are minimal in size and complexity, a phenomenon known as streamlining that is thought to benefit them by lowering the material costs of replication and maximizing transport functions that are essential to competition at ultralow nutrient concentrations. One of the surprises in SAR11 metabolism is their ability to both oxidize and produce a variety of volatile organic compounds that can diffuse into the atmosphere. SAR11 cells divide slowly and lack many forms of regulation commonly used by bacterial cells to adjust to changing environmental conditions. As a result of genome reduction, they require an unusual range of nutrients, which leads to complex biochemical interactions with other plankton. The study of SAR11 is providing insight into the biogeochemistry of labile DOM and is affecting microbiology beyond marine science by providing a model for understanding the evolution and function of streamlined cells.

  14. SAR11 bacteria linked to ocean anoxia and nitrogen loss

    Science.gov (United States)

    Tsementzi, Despina; Wu, Jieying; Deutsch, Samuel; Nath, Sangeeta; Rodriguez-R, Luis M.; Burns, Andrew S.; Ranjan, Piyush; Sarode, Neha; Malmstrom, Rex R.; Padilla, Cory C.; Stone, Benjamin K.; Bristow, Laura A.; Larsen, Morten; Glass, Jennifer B.; Thamdrup, Bo; Woyke, Tanja; Konstantinidis, Konstantinos T.; Stewart, Frank J.

    2016-08-01

    Bacteria of the SAR11 clade constitute up to one half of all microbial cells in the oxygen-rich surface ocean. SAR11 bacteria are also abundant in oxygen minimum zones (OMZs), where oxygen falls below detection and anaerobic microbes have vital roles in converting bioavailable nitrogen to N2 gas. Anaerobic metabolism has not yet been observed in SAR11, and it remains unknown how these bacteria contribute to OMZ biogeochemical cycling. Here, genomic analysis of single cells from the world’s largest OMZ revealed previously uncharacterized SAR11 lineages with adaptations for life without oxygen, including genes for respiratory nitrate reductases (Nar). SAR11 nar genes were experimentally verified to encode proteins catalysing the nitrite-producing first step of denitrification and constituted ~40% of OMZ nar transcripts, with transcription peaking in the anoxic zone of maximum nitrate reduction activity. These results link SAR11 to pathways of ocean nitrogen loss, redefining the ecological niche of Earth’s most abundant organismal group.

  15. Filters in topology optimization

    DEFF Research Database (Denmark)

    Bourdin, Blaise

    1999-01-01

    In this article, a modified (``filtered'') version of the minimum compliance topology optimization problem is studied. The direct dependence of the material properties on its pointwise density is replaced by a regularization of the density field using a convolution operator. In this setting...... it is possible to establish the existence of solutions. Moreover, convergence of an approximation by means of finite elements can be obtained. This is illustrated through some numerical experiments. The ``filtering'' technique is also shown to cope with two important numerical problems in topology optimization...

  16. A PC Controlled Filter

    Directory of Open Access Journals (Sweden)

    M. Van Looy

    1998-12-01

    Full Text Available In this paper we present a switched capacitor filter design using the SC22324 1C, which is fitted with an E2PROM. It contains four digitally programmable switched-capacitor filter sections, in order to obtain different responses. The SC22324 also contains the on-chip RAM. We'd like to explain, how could the on-chip RAM controlled via a PC. In this way the chip may be used afterwards with a menu where the user may select the wanted parameters.

  17. Parzen Particle Filters

    DEFF Research Database (Denmark)

    Lehn-Schiøler, Tue; Erdogmus, Deniz; Principe, Jose C.

    2004-01-01

    Using a Parzen density estimator any distribution can be approximated arbitrarily close by a sum of kernels. In particle filtering this fact is utilized to estimate a probability density function with Dirac delta kernels; when the distribution is discretized it becomes possible to solve an otherw......Using a Parzen density estimator any distribution can be approximated arbitrarily close by a sum of kernels. In particle filtering this fact is utilized to estimate a probability density function with Dirac delta kernels; when the distribution is discretized it becomes possible to solve...

  18. Unsupervised SBAS-DInSAR Processing of Space-borne SAR data for Earth Surface Displacement Time Series Generation

    Science.gov (United States)

    Casu, F.; de Luca, C.; Lanari, R.; Manunta, M.; Zinno, I.

    2016-12-01

    During the last 25 years, the Differential Synthetic Aperture Radar Interferometry (DInSAR) has played an important role for understanding the Earth's surface deformation and its dynamics. In particular, the large collections of SAR data acquired by a number of space-borne missions (ERS, ENVISAT, ALOS, RADARSAT, TerraSAR-X, COSMO-SkyMed) have pushed toward the development of advanced DInSAR techniques for monitoring the temporal evolution of the ground displacements with an high spatial density. Moreover, the advent of the Copernicus Sentinel-1 (S1) constellation is providing a further increase in the SAR data flow available to the Earth science community, due to its characteristics of global coverage strategy and free and open access data policy. Therefore, managing and storing such a huge amount of data, processing it in an effcient way and maximizing the available archives exploitation are becoming high priority issues. In this work we present some recent advances in the DInSAR field for dealing with the effective exploitation of the present and future SAR data archives. In particular, an efficient parallel SBAS implementation (namely P-SBAS) that takes benefit from high performance computing is proposed. Then, the P-SBAS migration to the emerging Cloud Computing paradigm is shown, together with extensive tests carried out in the Amazon's Elastic Cloud Compute (EC2) infrastructure. Finally, the integration of the P-SBAS processing chain within the ESA Geohazards Exploitation Platform (GEP), for setting up operational on-demand and systematic web tools, open to every user, aimed at automatically processing stacks of SAR data for the generation of SBAS displacement time series, is also illustrated. A number of experimental results obtained by using the ERS, ENVISAT and S1 data in areas characterized by volcanic, seismic and anthropogenic phenomena will be shown. This work is partially supported by: the DPC-CNR agreement, the EPOS-IP project and the ESA GEP project.

  19. InSAR Scientific Computing Environment

    Science.gov (United States)

    Rosen, Paul A.; Sacco, Gian Franco; Gurrola, Eric M.; Zabker, Howard A.

    2011-01-01

    This computing environment is the next generation of geodetic image processing technology for repeat-pass Interferometric Synthetic Aperture (InSAR) sensors, identified by the community as a needed capability to provide flexibility and extensibility in reducing measurements from radar satellites and aircraft to new geophysical products. This software allows users of interferometric radar data the flexibility to process from Level 0 to Level 4 products using a variety of algorithms and for a range of available sensors. There are many radar satellites in orbit today delivering to the science community data of unprecedented quantity and quality, making possible large-scale studies in climate research, natural hazards, and the Earth's ecosystem. The proposed DESDynI mission, now under consideration by NASA for launch later in this decade, would provide time series and multiimage measurements that permit 4D models of Earth surface processes so that, for example, climate-induced changes over time would become apparent and quantifiable. This advanced data processing technology, applied to a global data set such as from the proposed DESDynI mission, enables a new class of analyses at time and spatial scales unavailable using current approaches. This software implements an accurate, extensible, and modular processing system designed to realize the full potential of InSAR data from future missions such as the proposed DESDynI, existing radar satellite data, as well as data from the NASA UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar), and other airborne platforms. The processing approach has been re-thought in order to enable multi-scene analysis by adding new algorithms and data interfaces, to permit user-reconfigurable operation and extensibility, and to capitalize on codes already developed by NASA and the science community. The framework incorporates modern programming methods based on recent research, including object-oriented scripts controlling legacy and

  20. Open Foris SAR Toolkit-Free and Open Source Command Line Utilities for Automatized SAR Data Pre-Processing

    Science.gov (United States)

    Vollrath, Andreas; Lindquist, Erik; Jonckheere, Inge; Pekkarinen, Anssi

    2016-08-01

    In this paper, we present the Open Foris SAR Toolkit (OFST). OFST is a set of command line tools that focus on the automation for the (pre-) processing of Synthetic Aperture Radar (SAR) data in order to obtain higher level data products that are ready-to-use for classification and related subsequent tasks. For the actual SAR processing steps it uses the algorithms implemented in the Sentinel Applications Platform (SNAP) provided by ESA. Since the provision is free and open and no prior knowledge on SAR processing is necessary, we presume that the tools can help to enlarge the uptake of SAR data by non-experts. Furthermore, the high degree of automation makes it easy to integrate the tools into web-based processing services that can deal with the resource demanding handling of the imagery. By now the tools support the (pre-) processing of ALOS PALSAR and Sentinel-1 data. Some examples from large-area wall-to-wall mapping show that despite the complexity of SAR processing it is possible to automatically retrieve useful datasets for different applications.

  1. Enhanced Optical Filter Design

    CERN Document Server

    Cushing, David

    2011-01-01

    This book serves as a supplement to the classic texts by Angus Macleod and Philip Baumeister, taking an intuitive approach to the enhancement of optical coating (or filter) performance. Drawing from 40 years of experience in thin film design, Cushing introduces the basics of thin films, the commonly used materials and their deposition, the major coatings and their applications, and improvement methods for each.

  2. The ATLAS event filter

    CERN Document Server

    Beck, H P; Boissat, C; Davis, R; Duval, P Y; Etienne, F; Fede, E; Francis, D; Green, P; Hemmer, F; Jones, R; MacKinnon, J; Mapelli, Livio P; Meessen, C; Mommsen, R K; Mornacchi, Giuseppe; Nacasch, R; Negri, A; Pinfold, James L; Polesello, G; Qian, Z; Rafflin, C; Scannicchio, D A; Stanescu, C; Touchard, F; Vercesi, V

    1999-01-01

    An overview of the studies for the ATLAS Event Filter is given. The architecture and the high level design of the DAQ-1 prototype is presented. The current status if the prototypes is briefly given. Finally, future plans and milestones are given. (11 refs).

  3. Sand Filter Technology

    Science.gov (United States)

    2016-08-01

    EXWC) performed the evaluation at the Naval Air Station Lemoore, CA . The two year evaluation period began with one year of sand filter operation...appear dirty? If you answered “ yes ” to the first question and “ yes ” to either of the other questions, investigate this technology for your

  4. Fast Anisotropic Gauss Filters

    NARCIS (Netherlands)

    Geusebroek, J.M.; Smeulders, A.W.M.; van de Weijer, J.

    2003-01-01

    We derive the decomposition of the anisotropic Gaussian in a one dimensional Gauss filter in the x-direction phi. So also the anisotropic Gaussian can be decomposed by dimension. This appears to be extremely efficient from a computing perspective. An implementation scheme for normal covolution and

  5. Ceramic HEPA Filter Program

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, M A; Bergman, W; Haslam, J; Brown, E P; Sawyer, S; Beaulieu, R; Althouse, P; Meike, A

    2012-04-30

    Potential benefits of ceramic filters in nuclear facilities: (1) Short term benefit for DOE, NRC, and industry - (a) CalPoly HTTU provides unique testing capability to answer questions for DOE - High temperature testing of materials, components, filter, (b) Several DNFSB correspondences and presentations by DNFSB members have highlighted the need for HEPA filter R and D - DNFSB Recommendation 2009-2 highlighted a nuclear facility response to an evaluation basis earthquake followed by a fire (aka shake-n-bake) and CalPoly has capability for a shake-n-bake test; (2) Intermediate term benefit for DOE and industry - (a) Filtration for specialty applications, e.g., explosive applications at Nevada, (b) Spin-off technologies applicable to other commercial industries; and (3) Long term benefit for DOE, NRC, and industry - (a) Across industry, strong desire for better performance filter, (b) Engineering solution to safety problem will improve facility safety and decrease dependence on associated support systems, (c) Large potential life-cycle cost savings, and (d) Facilitates development and deployment of LLNL process innovations to allow continuous ventilation system operation during a fire.

  6. Underwater Sound Filtering

    NARCIS (Netherlands)

    Rutger van Aalst; Ines Simic

    2015-01-01

    This paper describes a possible solution to the underwater sound filtering problem, using Blind Source Separation. The problem regards splitting sound from a boat engine and the water waves to prove the possibility to extract one sound fragment from the other on the open sea. The illustrations shown

  7. DEMONSTRATION BULLETIN: COLLOID POLISHING FILTER METHOD - FILTER FLOW TECHNOLOGY, INC.

    Science.gov (United States)

    The Filter Flow Technology, Inc. (FFT) Colloid Polishing Filter Method (CPFM) was tested as a transportable, trailer mounted, system that uses sorption and chemical complexing phenomena to remove heavy metals and nontritium radionuclides from water. Contaminated waters can be pro...

  8. Geodetic imaging of tectonic deformation with InSAR

    Science.gov (United States)

    Fattahi, Heresh

    Precise measurements of ground deformation across the plate boundaries are crucial observations to evaluate the location of strain localization and to understand the pattern of strain accumulation at depth. Such information can be used to evaluate the possible location and magnitude of future earthquakes. Interferometric Synthetic Aperture Radar (InSAR) potentially can deliver small-scale (few mm/yr) ground displacement over long distances (hundreds of kilometers) across the plate boundaries and over continents. However, Given the ground displacement as our signal of interest, the InSAR observations of ground deformation are usually affected by several sources of systematic and random noises. In this dissertation I identify several sources of systematic and random noise, develop new methods to model and mitigate the systematic noise and to evaluate the uncertainty of the ground displacement measured with InSAR. I use the developed approach to characterize the tectonic deformation and evaluate the rate of strain accumulation along the Chaman fault system, the western boundary of the India with Eurasia tectonic plates. I evaluate the bias due to the topographic residuals in the InSAR range-change time-series and develope a new method to estimate the topographic residuals and mitigate the effect from the InSAR range-change time-series (Chapter 2). I develop a new method to evaluate the uncertainty of the InSAR velocity field due to the uncertainty of the satellite orbits (Chapter 3) and a new algorithm to automatically detect and correct the phase unwrapping errors in a dense network of interferograms (Chapter 4). I develop a new approach to evaluate the impact of systematic and stochastic components of the tropospheric delay on the InSAR displacement time-series and its uncertainty (Chapter 5). Using the new InSAR time-series approach developed in the previous chapters, I study the tectonic deformation across the western boundary of the India plate with Eurasia and

  9. Bandwidth requirements for fine resolution squinted SAR

    Energy Technology Data Exchange (ETDEWEB)

    DOERRY,ARMIN W.

    2000-03-01

    The conventional rule-of-thumb for Synthetic Aperture Radar is that an RF bandwidth of c/(2{rho}{sub r}) is required to image a scene at the desired slant-range resolution {rho}{sub r}, and perhaps a little more to account for window functions and sidelobe control. This formulation is based on the notion that the total bandwidth required is the same bandwidth that is required for a single pulse. What is neglected is that efficient processing of an entire synthetic aperture of pulses will often require different frequency content for each of the different pulses that makeup a synthetic aperture. Consequently, the total RF bandwidth required of a Synthetic Aperture Radar may then be substantially wider than the bandwidth of any single pulse. The actual RF bandwidth required depends strongly on flight geometry, owing to the desire for a radar to maintain a constant projection of the Fourier space collection surface onto the {omega}{sub y} axis. Long apertures required for fine azimuth resolution, and severe squint angles with steep depression angles may require total RF bandwidths well beyond the minimum bandwidth required of any single transmitted pulse, perhaps even by a factor of two or more. Accounting for this is crucial to designing efficient versatile high-performance imaging radars. This paper addresses how a data set conducive to efficient processing might increase the total RF bandwidth, and presents examples of how a fixed RF bandwidth might then limit SAR geometries.

  10. Message concerning Severe Acute Respiratory Syndrome ("SARS")

    CERN Multimedia

    2003-01-01

    IMPORTANT REMINDER If you have just come back from one of the regions identified by the WHO as being infected with SARS, it is essential to monitor your state of health for ten days after your return. The syndrome manifests itself in the rapid onset of a high fever combined with respiratory problems (coughing, breathlessness, breathing difficulty). Should these signs appear, you must contact the CERN Medical Service as quickly as possible on number 73802 or 73186 during normal working hours, and the fire brigade at all other times on number 74444, indicating that you have just returned from one of the WHO-identified areas with recent local transmission.China: Beijing, Hong Kong (Special Administrative Region), Guangdong Province, Inner Mongolia, Shanxi Province, Tianjin ProvinceTaiwan:TaipeiMoreover, until further notice the CERN Management requests that all trips to these various regions of the world be reduced to a strict minimum and then only with the consent of the Division Leader concerned. Anyone comin...

  11. Spoof surface plasmon-based bandpass filter with extremely wide upper stopband

    Science.gov (United States)

    Xiaoyong, Liu; Lei, Zhu; Yijun, Feng

    2016-03-01

    We investigate the guiding modes of spoof surface plasmon polaritons (SPPs) on a symmetric ultra-thin plasmonic structure. From the analysis, we deduce the operating frequency region of the single-mode propagation. Based on this property, a spoof SPPs lowpass filter is then constituted in the microwave frequency. By introducing a transmission zero at the lower frequency band using a pair of stepped-impedance stubs, a wide passband filter is further realized. The proposed filter is fed by a transducer composed of a microstrip line with a flaring ground. The simulated results show that the presented filter has an extremely wide upper stopband in addition to excellent passband filtering characteristics such as low loss, wide band, and high square ratio. A prototype passband filter is also fabricated to validate the predicted performances. The proposed spoof-SPPs filter is believed to be very promising for other surface waveguide components in microwave and terahertz bands. Project supported by the Key Grant Project of Ministry of Education of China (Grant No. 313029), the FDCT Research Grant from Macao Science and Technology Development Fund, China (Grant No. 051/2014/A1), and the Multi-Year Research Grant from University of Macau, Macau SAR, China (Grant No. MYRG2014-00079-FST).

  12. Numerical study of canister filters with alternatives filter cap configurations

    Science.gov (United States)

    Mohammed, A. N.; Daud, A. R.; Abdullah, K.; Seri, S. M.; Razali, M. A.; Hushim, M. F.; Khalid, A.

    2017-09-01

    Air filtration system and filter play an important role in getting a good quality air into turbo machinery such as gas turbine. The filtration system and filter has improved the quality of air and protect the gas turbine part from contaminants which could bring damage. During separation of contaminants from the air, pressure drop cannot be avoided but it can be minimized thus helps to reduce the intake losses of the engine [1]. This study is focused on the configuration of the filter in order to obtain the minimal pressure drop along the filter. The configuration used is the basic filter geometry provided by Salutary Avenue Manufacturing Sdn Bhd. and two modified canister filter cap which is designed based on the basic filter model. The geometries of the filter are generated by using SOLIDWORKS software and Computational Fluid Dynamics (CFD) software is used to analyse and simulates the flow through the filter. In this study, the parameters of the inlet velocity are 0.032 m/s, 0.063 m/s, 0.094 m/s and 0.126 m/s. The total pressure drop produce by basic, modified filter 1 and 2 is 292.3 Pa, 251.11 Pa and 274.7 Pa. The pressure drop reduction for the modified filter 1 is 41.19 Pa and 14.1% lower compared to basic filter and the pressure drop reduction for modified filter 2 is 17.6 Pa and 6.02% lower compared to the basic filter. The pressure drops for the basic filter are slightly different with the Salutary Avenue filter due to limited data and experiment details. CFD software are very reliable in running a simulation rather than produces the prototypes and conduct the experiment thus reducing overall time and cost in this study.

  13. FPGA implementation of filtered image using 2D Gaussian filter

    OpenAIRE

    Leila kabbai; Anissa Sghaier; Ali Douik; Mohsen Machhout

    2016-01-01

    Image filtering is one of the very useful techniques in image processing and computer vision. It is used to eliminate useless details and noise from an image. In this paper, a hardware implementation of image filtered using 2D Gaussian Filter will be present. The Gaussian filter architecture will be described using a different way to implement convolution module. Thus, multiplication is in the heart of convolution module, for this reason, three different ways to implement multiplication opera...

  14. Generalized Selection Weighted Vector Filters

    Directory of Open Access Journals (Sweden)

    Rastislav Lukac

    2004-09-01

    Full Text Available This paper introduces a class of nonlinear multichannel filters capable of removing impulsive noise in color images. The here-proposed generalized selection weighted vector filter class constitutes a powerful filtering framework for multichannel signal processing. Previously defined multichannel filters such as vector median filter, basic vector directional filter, directional-distance filter, weighted vector median filters, and weighted vector directional filters are treated from a global viewpoint using the proposed framework. Robust order-statistic concepts and increased degree of freedom in filter design make the proposed method attractive for a variety of applications. Introduced multichannel sigmoidal adaptation of the filter parameters and its modifications allow to accommodate the filter parameters to varying signal and noise statistics. Simulation studies reported in this paper indicate that the proposed filter class is computationally attractive, yields excellent performance, and is able to preserve fine details and color information while efficiently suppressing impulsive noise. This paper is an extended version of the paper by Lukac et al. presented at the 2003 IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03 in Grado, Italy.

  15. UAVSAR and TerraSAR-X Based InSAR Detection of Localized Subsidence in the New Orleans Area

    Science.gov (United States)

    Blom, R. G.; An, K.; Jones, C. E.; Latini, D.

    2014-12-01

    Vulnerability of the US Gulf coast to inundation has received increased attention since hurricanes Katrina and Rita. Compounding effects of sea level rise, wetland loss, and regional and local subsidence makes flood protection a difficult challenge, and particularly for the New Orleans area. Key to flood protection is precise knowledge of elevations and elevation changes. Analysis of historical and continuing geodetic measurements show surprising complexity, including locations subsiding more rapidly than considered during planning of hurricane protection and coastal restoration projects. Combining traditional, precise geodetic data with interferometric synthetic aperture radar (InSAR) observations can provide geographically dense constraints on surface deformation. The Gulf Coast environment is challenging for InSAR techniques, especially with systems not designed for interferometry. We use two InSAR capable systems, the L- band (24 cm wavelength) airborne JPL/NASA UAVSAR, and the DLR/EADS Astrium spaceborne TerraSAR X-band (3 cm wavelength), and compare results. First, we are applying pair-wise InSAR to the longer wavelength UAVSAR data to detect localized elevation changes potentially impacting flood protection infrastructure from 2009 - 2014. We focus on areas on and near flood protection infrastructure to identify changes indicative of subsidence, structural deformation, and/or seepage. The Spaceborne TerraSAR X-band SAR system has relatively frequent observations, and dense persistent scatterers in urban areas, enabling measurement of very small displacements. We compare L-band UAVSAR results with permanent scatterer (PS-InSAR) and Short Baseline Subsets (SBAS) interferometric analyses of a stack composed by 28 TerraSAR X-band images acquired over the same period. Thus we can evaluate results from the different radar frequencies and analyses techniques. Preliminary results indicate subsidence features potentially of a variety of causes, including ground water

  16. The InSAR Scientific Computing Environment (ISCE): An Earth Science SAR Processing Framework, Toolbox, and Foundry

    Science.gov (United States)

    Agram, P. S.; Gurrola, E. M.; Lavalle, M.; Sacco, G. F.; Rosen, P. A.

    2016-12-01

    The InSAR Scientific Computing Environment (ISCE) provides both a modular, flexible, and extensible framework for building software components and applications that work together seamlessly as well as a toolbox for processing InSAR data into higher level geodetic image products from a diverse array of radar satellites and aircraft. ISCE easily scales to serve as the SAR processing engine at the core of the NASA JPL Advanced Rapid Imaging and Analysis (ARIA) Center for Natural Hazards as well as a software toolbox for individual scientists working with SAR data. ISCE is planned as the foundational element in processing NISAR data, enabling a new class of analyses that take greater advantage of the long time and large spatial scales of these data. ISCE in ARIA is also a SAR Foundry for development of new processing components and workflows to meet the needs of both large processing centers and individual users. The ISCE framework contains object-oriented Python components layered to construct Python InSAR components that manage legacy Fortran/C InSAR programs. The Python user interface enables both command-line deployment of workflows as well as an interactive "sand box" (the Python interpreter) where scientists can "play" with the data. Recent developments in ISCE include the addition of components to ingest Sentinel-1A SAR data (both stripmap and TOPS-mode) and a new workflow for processing the TOPS-mode data. New components are being developed to exploit polarimetric-SAR data to provide the ecosystem and land-cover/land-use change communities with rigorous and efficient tools to perform multi-temporal, polarimetric and tomographic analyses in order to generate calibrated, geocoded and mosaicked Level-2 and Level-3 products (e.g., maps of above-ground biomass or forest disturbance). ISCE has been downloaded by over 200 users by a license for WinSAR members through the Unavco.org website. Others may apply directly to JPL for a license at download.jpl.nasa.gov.

  17. Hydrodynamics of microbial filter feeding

    DEFF Research Database (Denmark)

    Nielsen, Lasse Tor; Asadzadeh, Seyed Saeed; Dölger, Julia

    2017-01-01

    Microbial filter feeders are an important group of grazers, significant to the microbial loop, aquatic food webs, and biogeochemical cycling. Our understanding of microbial filter feeding is poor, and, importantly, it is unknown what force microbial filter feeders must generate to process adequate...... amounts of water. Also, the trade-off in the filter spacing remains unexplored, despite its simple formulation: A filter too coarse will allow suitably sized prey to pass unintercepted, whereas a filter too fine will cause strong flow resistance. We quantify the feeding flow of the filter......-feeding choanoflagellate Diaphanoeca grandis using particle tracking, and demonstrate that the current understanding of microbial filter feeding is inconsistent with computational fluid dynamics (CFD) and analytical estimates. Both approaches underestimate observed filtration rates by more than an order of magnitude...

  18. Analog filters in nanometer CMOS

    CERN Document Server

    Uhrmann, Heimo; Zimmermann, Horst

    2014-01-01

    Starting from the basics of analog filters and the poor transistor characteristics in nanometer CMOS 10 high-performance analog filters developed by the authors in 120 nm and 65 nm CMOS are described extensively. Among them are gm-C filters, current-mode filters, and active filters for system-on-chip realization for Bluetooth, WCDMA, UWB, DVB-H, and LTE applications. For the active filters several operational amplifier designs are described. The book, furthermore, contains a review of the newest state of research on low-voltage low-power analog filters. To cover the topic of the book comprehensively, linearization issues and measurement methods for the characterization of advanced analog filters are introduced in addition. Numerous elaborate illustrations promote an easy comprehension. This book will be of value to engineers and researchers in industry as well as scientists and Ph.D students at universities. The book is also recommendable to graduate students specializing on nanoelectronics, microelectronics ...

  19. Memory T cell responses targeting the SARS coronavirus persist up to 11 years post-infection.

    Science.gov (United States)

    Ng, Oi-Wing; Chia, Adeline; Tan, Anthony T; Jadi, Ramesh S; Leong, Hoe Nam; Bertoletti, Antonio; Tan, Yee-Joo

    2016-04-12

    Severe acute respiratory syndrome (SARS) is a highly contagious infectious disease which first emerged in late 2002, caused by a then novel human coronavirus, SARS coronavirus (SARS-CoV). The virus is believed to have originated from bats and transmitted to human through intermediate animals such as civet cats. The re-emergence of SARS-CoV remains a valid concern due to the continual persistence of zoonotic SARS-CoVs and SARS-like CoVs (SL-CoVs) in bat reservoirs. In this study, the screening for the presence of SARS-specific T cells in a cohort of three SARS-recovered individuals at 9 and 11 years post-infection was carried out, and all memory T cell responses detected target the SARS-CoV structural proteins. Two CD8(+) T cell responses targeting the SARS-CoV membrane (M) and nucleocapsid (N) proteins were characterized by determining their HLA restriction and minimal T cell epitope regions. Furthermore, these responses were found to persist up to 11 years post-infection. An absence of cross-reactivity of these CD8(+) T cell responses against the newly-emerged Middle East respiratory syndrome coronavirus (MERS-CoV) was also demonstrated. The knowledge of the persistence of SARS-specific celullar immunity targeting the viral structural proteins in SARS-recovered individuals is important in the design and development of SARS vaccines, which are currently unavailable. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Validation testing of radioactive waste drum filter vents

    Energy Technology Data Exchange (ETDEWEB)

    Weber, L.D. [Pall Corp., Port Washington, NY (United States); Rahimi, R.S. [Pall Corp., Cortland, NY (United States); Edling, D. [Edling & Associates, Inc., Russel Springs, KY (United States)

    1997-08-01

    The minimum requirements for Drum Filter Vents (DFVs) can be met by demonstrating conformance with the Waste Isolation Pilot Plant (WIPP) Trupact II Safety Assessment Report (SAR), and conformance with U.S. Federal shipping regulations 49 CFR 178.350, DOT Spec 7A, for Type A packages. These together address a number of safety related performance parameters such as hydrogen diffusivity, flow related pressure drop, filtration efficiency and, separately, mechanical stability and the ability to prevent liquid water in-leakage. In order to make all metal DFV technology (including metallic filter medium) available to DOE sites, Pall launched a product development program to validate an all metal design to meet these requirements. Numerous problems experienced by DOE sites in the past came to light during this development program. They led us to explore enhancements to DFV design and performance testing addressing these difficulties and concerns. The result is a patented all metal DFV certified to all applicable regulatory requirements, which for the first time solves operational and health safety problems reported by DOE site personnel but not addressed by previous DFV`s. The new technology facilitates operations (such as manual, automated and semi-automated drum handling/redrumming), sampling, on-site storage, and shipping. At the same time, it upgrades filtration efficiency in configurations documented to maintain filter efficiency following mechanical stress. 2 refs., 2 figs., 10 tabs.

  1. Satellite SAR interferometric techniques applied to emergency mapping

    Science.gov (United States)

    Stefanova Vassileva, Magdalena; Riccardi, Paolo; Lecci, Daniele; Giulio Tonolo, Fabio; Boccardo Boccardo, Piero; Chiesa, Giuliana; Angeluccetti, Irene

    2017-04-01

    This paper aim to investigate the capabilities of the currently available SAR interferometric algorithms in the field of emergency mapping. Several tests have been performed exploiting the Copernicus Sentinel-1 data using the COTS software ENVI/SARscape 5.3. Emergency Mapping can be defined as "creation of maps, geo-information products and spatial analyses dedicated to providing situational awareness emergency management and immediate crisis information for response by means of extraction of reference (pre-event) and crisis (post-event) geographic information/data from satellite or aerial imagery". The conventional differential SAR interferometric technique (DInSAR) and the two currently available multi-temporal SAR interferometric approaches, i.e. Permanent Scatterer Interferometry (PSI) and Small BAseline Subset (SBAS), have been applied to provide crisis information useful for the emergency management activities. Depending on the considered Emergency Management phase, it may be distinguished between rapid mapping, i.e. fast provision of geospatial data regarding the area affected for the immediate emergency response, and monitoring mapping, i.e. detection of phenomena for risk prevention and mitigation activities. In order to evaluate the potential and limitations of the aforementioned SAR interferometric approaches for the specific rapid and monitoring mapping application, five main factors have been taken into account: crisis information extracted, input data required, processing time and expected accuracy. The results highlight that DInSAR has the capacity to delineate areas affected by large and sudden deformations and fulfills most of the immediate response requirements. The main limiting factor of interferometry is the availability of suitable SAR acquisition immediately after the event (e.g. Sentinel-1 mission characterized by 6-day revisiting time may not always satisfy the immediate emergency request). PSI and SBAS techniques are suitable to produce

  2. Seasonal Inundation Monitoring of Northern Pantanal Wetland, Brazil Using ALOS SAR/InSAR and Envisat Altimetry

    Science.gov (United States)

    Kim, J.; Calmant, S.; Lee, H.; Lu, Z.; Shum, C.

    2011-12-01

    The Pantanal is one of the most biologically diverse ecosystems and largest wetland in the world. It has been threatened by massive economic development, and anthropogenic climate change. At the current rate, the Brazilian Pantanal will disappear within 45 years, according to 2006 report by Conservation International. Here, we illustrate that the evolutions of the Pantanal can be characterized by using ALOS PALSAR Fine-Beam and ScanSAR mode images, and Envisat radar altimetry. Multi-mode of high resolution and large-scale SAR images were used to unveil temporal and spatial inundation patterns. The backscattering coefficient of multi-mode SAR images shows regular change pattern in response to periodic inundation. InSAR analysis allows us to recognize that the temporal variation is not spatially constant, which is distinct among other wetlands, e.g., Louisiana wetlands. In addition to SAR/InSAR data, radar Altimetry (Envisat) is critical for providing vertical datum and fine temporal resolution, towards characterization of the Pantanal wetland condition during inundation. The observed close correlation between inundation area from SAR images and hydraulic change from a river gauge implies that the Pantanal is vulnerable to external effects presumably by human activities, and abnormal hydraulic change can threaten the ecosystems and biological diversity. We conclude that radar remote sensing data can provide timely and high-resolution monitoring of hydraulic characteristics of the Pantanal, one of the least-known and most fragile wetlands, and they can potentially be used as an efficient tool for remote wetland monitoring and ecological studies.

  3. The Rao-Blackwellized Particle Filter: A Filter Bank Implementation

    Directory of Open Access Journals (Sweden)

    Karlsson Rickard

    2010-01-01

    Full Text Available For computational efficiency, it is important to utilize model structure in particle filtering. One of the most important cases occurs when there exists a linear Gaussian substructure, which can be efficiently handled by Kalman filters. This is the standard formulation of the Rao-Blackwellized particle filter (RBPF. This contribution suggests an alternative formulation of this well-known result that facilitates reuse of standard filtering components and which is also suitable for object-oriented programming. Our RBPF formulation can be seen as a Kalman filter bank with stochastic branching and pruning.

  4. Multilevel particle filter

    KAUST Repository

    Law, Kody

    2016-01-06

    This talk will pertain to the filtering of partially observed diffusions, with discrete-time observations. It is assumed that only biased approximations of the diffusion can be obtained, for choice of an accuracy parameter indexed by l. A multilevel estimator is proposed, consisting of a telescopic sum of increment estimators associated to the successive levels. The work associated to O( 2) mean-square error between the multilevel estimator and average with respect to the filtering distribution is shown to scale optimally, for example as O( 2) for optimal rates of convergence of the underlying diffusion approximation. The method is illustrated on some toy examples as well as estimation of interest rate based on real S&P 500 stock price data.

  5. Atmospheric Effects on InSAR Measurements and Their Mitigation

    Directory of Open Access Journals (Sweden)

    Jiang-ping Long

    2008-09-01

    Full Text Available Interferometric Synthetic Aperture Radar (InSAR is a powerful technology for observing the Earth surface, especially for mapping the Earth's topography and deformations. InSAR measurements are however often significantly affected by the atmosphere as the radar signals propagate through the atmosphere whose state varies both in space and in time. Great efforts have been made in recent years to better understand the properties of the atmospheric effects and to develop methods for mitigating the effects. This paper provides a systematic review of the work carried out in this area. The basic principles of atmospheric effects on repeat-pass InSAR are first introduced. The studies on the properties of the atmospheric effects, including the magnitudes of the effects determined in the various parts of the world, the spectra of the atmospheric effects, the isotropic properties and the statistical distributions of the effects, are then discussed. The various methods developed for mitigating the atmospheric effects are then reviewed, including the methods that are based on PSInSAR processing, the methods that are based on interferogram modeling, and those that are based on external data such as GPS observations, ground meteorological data, and satellite data including those from the MODIS and MERIS. Two examples that use MODIS and MERIS data respectively to calibrate atmospheric effects on InSAR are also given.

  6. Atmospheric Effects on InSAR Measurements and Their Mitigation.

    Science.gov (United States)

    Ding, Xiao-Li; Li, Zhi-Wei; Zhu, Jian-Jun; Feng, Guang-Cai; Long, Jiang-Ping

    2008-09-03

    Interferometric Synthetic Aperture Radar (InSAR) is a powerful technology for observing the Earth surface, especially for mapping the Earth's topography and deformations. InSAR measurements are however often significantly affected by the atmosphere as the radar signals propagate through the atmosphere whose state varies both in space and in time. Great efforts have been made in recent years to better understand the properties of the atmospheric effects and to develop methods for mitigating the effects. This paper provides a systematic review of the work carried out in this area. The basic principles of atmospheric effects on repeat-pass InSAR are first introduced. The studies on the properties of the atmospheric effects, including the magnitudes of the effects determined in the various parts of the world, the spectra of the atmospheric effects, the isotropic properties and the statistical distributions of the effects, are then discussed. The various methods developed for mitigating the atmospheric effects are then reviewed, including the methods that are based on PSInSAR processing, the methods that are based on interferogram modeling, and those that are based on external data such as GPS observations, ground meteorological data, and satellite data including those from the MODIS and MERIS. Two examples that use MODIS and MERIS data respectively to calibrate atmospheric effects on InSAR are also given.

  7. Targeted Radiosensitization by the Chk1 Inhibitor SAR-020106

    Energy Technology Data Exchange (ETDEWEB)

    Borst, Gerben R., E-mail: g.borst@nki.nl [The Institute of Cancer Research, London (United Kingdom); Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands); McLaughlin, Martin; Kyula, Joan N.; Neijenhuis, Sari; Khan, Aadil; Good, James; Zaidi, Shane [The Institute of Cancer Research, London (United Kingdom); Powell, Ned G. [HPV Research Group, School of Medicine, Cardiff University, Cardiff (United Kingdom); Meier, Pascal; Collins, Ian; Garrett, Michelle D. [The Institute of Cancer Research, London (United Kingdom); Verheij, Marcel [Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands); Harrington, Kevin J. [The Institute of Cancer Research, London (United Kingdom)

    2013-03-15

    Purpose: To explore the activity of a potent Chk1 inhibitor (SAR-020106) in combination with radiation. Methods and Materials: Colony and mechanistic in vitro assays and a xenograft in vivo model. Results: SAR-020106 suppressed-radiation-induced G{sub 2}/M arrest and reduced clonogenic survival only in p53-deficient tumor cells. SAR-020106 promoted mitotic entry following irradiation in all cell lines, but p53-deficient cells were likely to undergo apoptosis or become aneuploid, while p53 wild-type cells underwent a postmitotic G{sub 1} arrest followed by subsequent normal cell cycle re-entry. Following combined treatment with SAR-020106 and radiation, homologous-recombination-mediated DNA damage repair was inhibited in all cell lines. A significant increase in the number of pan-γH2AX-staining apoptotic cells was observed only in p53-deficient cell lines. Efficacy was confirmed in vivo in a clinically relevant human head-and-neck cell carcinoma xenograft model. Conclusion: The Chk1 inhibitor SAR-020106 is a potent radiosensitizer in tumor cell lines defective in p53 signaling.

  8. Detecting and monitoring UCG subsidence with InSAR

    Energy Technology Data Exchange (ETDEWEB)

    Mellors, R J; Foxall, W; Yang, X

    2012-03-23

    The use of interferometric synthetic aperture radar (InSAR) to measure surface subsidence caused by Underground Coal Gasification (UCG) is tested. InSAR is a remote sensing technique that uses Synthetic Aperture Radar images to make spatial images of surface deformation and may be deployed from satellite or an airplane. With current commercial satellite data, the technique works best in areas with little vegetation or farming activity. UCG subsidence is generally caused by roof collapse, which adversely affects UCG operations due to gas loss and is therefore important to monitor. Previous studies have demonstrated the usefulness of InSAR in measuring surface subsidence related to coal mining and surface deformation caused by a coal mining roof collapse in Crandall Canyon, Utah is imaged as a proof-of-concept. InSAR data is collected and processed over three known UCG operations including two pilot plants (Majuba, South Africa and Wulanchabu, China) and an operational plant (Angren, Uzbekistan). A clear f eature showing approximately 7 cm of subsidence is observed in the UCG field in Angren. Subsidence is not observed in the other two areas, which produce from deeper coal seams and processed a smaller volume. The results show that in some cases, InSAR is a useful tool to image UCG related subsidence. Data from newer satellites and improved algorithms will improve effectiveness.

  9. Receptor recognition and cross-species infections of SARS coronavirus.

    Science.gov (United States)

    Li, Fang

    2013-10-01

    Receptor recognition is a major determinant of the host range, cross-species infections, and pathogenesis of the severe acute respiratory syndrome coronavirus (SARS-CoV). A defined receptor-binding domain (RBD) in the SARS-CoV spike protein specifically recognizes its host receptor, angiotensin-converting enzyme 2 (ACE2). This article reviews the latest knowledge about how RBDs from different SARS-CoV strains interact with ACE2 from several animal species. Detailed research on these RBD/ACE2 interactions has established important principles on host receptor adaptations, cross-species infections, and future evolution of SARS-CoV. These principles may apply to other emerging animal viruses, including the recently emerged Middle East respiratory syndrome coronavirus (MERS-CoV). This paper forms part of a series of invited articles in Antiviral Research on "From SARS to MERS: 10years of research on highly pathogenic human coronaviruses". Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Glacial lake mapping with very high resolution satellite SAR data

    Science.gov (United States)

    Strozzi, T.; Wiesmann, A.; Kääb, A.; Joshi, S.; Mool, P.

    2012-08-01

    Floods resulting from the outbursts of glacial lakes are among the most far-reaching disasters in high mountain regions. Glacial lakes are typically located in remote areas and space-borne remote sensing data are an important source of information about the occurrence and development of such lakes. Here we show that very high resolution satellite Synthetic Aperture Radar (SAR) data can be employed for reliably mapping glacial lakes. Results in the Alps, Pamir and Himalaya using TerraSAR-X and Radarsat-2 data are discussed in comparison to in-situ information, and high-resolution satellite optical and radar imagery. The performance of the satellite SAR data is best during the snow- and ice-free season. In the broader perspective of hazard management, the detection of glacial lakes and the monitoring of their changes from very high-resolution satellite SAR intensity images contributes to the initial assessment of hazards related to glacial lakes, but a more integrated, multi-level approach needs also to include other relevant information such as glacier outlines and outline changes or the identification of unstable slopes above the lake and the surrounding area, information types to which SAR analysis techniques can also contribute.

  11. A Localization Method for Multistatic SAR Based on Convex Optimization.

    Science.gov (United States)

    Zhong, Xuqi; Wu, Junjie; Yang, Jianyu; Sun, Zhichao; Huang, Yuling; Li, Zhongyu

    2015-01-01

    In traditional localization methods for Synthetic Aperture Radar (SAR), the bistatic range sum (BRS) estimation and Doppler centroid estimation (DCE) are needed for the calculation of target localization. However, the DCE error greatly influences the localization accuracy. In this paper, a localization method for multistatic SAR based on convex optimization without DCE is investigated and the influence of BRS estimation error on localization accuracy is analysed. Firstly, by using the information of each transmitter and receiver (T/R) pair and the target in SAR image, the model functions of T/R pairs are constructed. Each model function's maximum is on the circumference of the ellipse which is the iso-range for its model function's T/R pair. Secondly, the target function whose maximum is located at the position of the target is obtained by adding all model functions. Thirdly, the target function is optimized based on gradient descent method to obtain the position of the target. During the iteration process, principal component analysis is implemented to guarantee the accuracy of the method and improve the computational efficiency. The proposed method only utilizes BRSs of a target in several focused images from multistatic SAR. Therefore, compared with traditional localization methods for SAR, the proposed method greatly improves the localization accuracy. The effectivity of the localization approach is validated by simulation experiment.

  12. Determining Titan surface topography from Cassini SAR data

    Science.gov (United States)

    Stiles, Bryan W.; Hensley, Scott; Gim, Yonggyu; Bates, David M.; Kirk, Randolph L.; Hayes, Alex; Radebaugh, Jani; Lorenz, Ralph D.; Mitchell, Karl L.; Callahan, Philip S.; Zebker, Howard; Johnson, William T.K.; Wall, Stephen D.; Lunine, Jonathan I.; Wood, Charles A.; Janssen, Michael; Pelletier, Frederic; West, Richard D.; Veeramacheneni, Chandini

    2009-01-01

    A technique, referred to as SARTopo, has been developed for obtaining surface height estimates with 10 km horizontal resolution and 75 m vertical resolution of the surface of Titan along each Cassini Synthetic Aperture Radar (SAR) swath. We describe the technique and present maps of the co-located data sets. A global map and regional maps of Xanadu and the northern hemisphere hydrocarbon lakes district are included in the results. A strength of the technique is that it provides topographic information co-located with SAR imagery. Having a topographic context vastly improves the interpretability of the SAR imagery and is essential for understanding Titan. SARTopo is capable of estimating surface heights for most of the SAR-imaged surface of Titan. Currently nearly 30% of the surface is within 100 km of a SARTopo height profile. Other competing techniques provide orders of magnitude less coverage. We validate the SARTopo technique through comparison with known geomorphological features such as mountain ranges and craters, and by comparison with co-located nadir altimetry, including a 3000 km strip that had been observed by SAR a month earlier. In this area, the SARTopo and nadir altimetry data sets are co-located tightly (within 5-10 km for one 500 km section), have similar resolution, and as expected agree closely in surface height. Furthermore the region contains prominent high spatial resolution topography, so it provides an excellent test of the resolution and precision of both techniques.

  13. Coastline detection with time series of SAR images

    Science.gov (United States)

    Ao, Dongyang; Dumitru, Octavian; Schwarz, Gottfried; Datcu, Mihai

    2017-10-01

    For maritime remote sensing, coastline detection is a vital task. With continuous coastline detection results from satellite image time series, the actual shoreline, the sea level, and environmental parameters can be observed to support coastal management and disaster warning. Established coastline detection methods are often based on SAR images and wellknown image processing approaches. These methods involve a lot of complicated data processing, which is a big challenge for remote sensing time series. Additionally, a number of SAR satellites operating with polarimetric capabilities have been launched in recent years, and many investigations of target characteristics in radar polarization have been performed. In this paper, a fast and efficient coastline detection method is proposed which comprises three steps. First, we calculate a modified correlation coefficient of two SAR images of different polarization. This coefficient differs from the traditional computation where normalization is needed. Through this modified approach, the separation between sea and land becomes more prominent. Second, we set a histogram-based threshold to distinguish between sea and land within the given image. The histogram is derived from the statistical distribution of the polarized SAR image pixel amplitudes. Third, we extract continuous coastlines using a Canny image edge detector that is rather immune to speckle noise. Finally, the individual coastlines derived from time series of .SAR images can be checked for changes.

  14. Ocean Surface Wind Speed of Hurricane Helene Observed by SAR

    DEFF Research Database (Denmark)

    Xu, Qing; Cheng, Yongcun; Li, Xiaofeng

    2011-01-01

    The hurricanes can be detected by many remote sensors, but synthetic aperture radar (SAR) can yield high-resolution (sub-kilometer) and low-level wind information that cannot be seen below the cloud by other sensors. In this paper, an assessment of SAR capability of monitoring high-resolution hur......The hurricanes can be detected by many remote sensors, but synthetic aperture radar (SAR) can yield high-resolution (sub-kilometer) and low-level wind information that cannot be seen below the cloud by other sensors. In this paper, an assessment of SAR capability of monitoring high......-resolution hurricane was conducted. A case study was carried out to retrieve ocean surface wind field from C-band RADARSAT-1 SAR image which captured the structure of hurricane Helene over the Atlantic Ocean on 20 September, 2006. With wind direction from the outputs of U.S. Navy Operational Global Atmospheric...... Prediction System (NOGAPS) model, C-band geophysical model functions (GMFs) which describe the normalized radar cross section (NRCS) dependence on the wind speed and the geometry of radar observations (i.e., incidence angle and azimuth angle with respect to wind direction) such as CMOD5 and newly developed...

  15. Particle flow superpositional GLMB filter

    Science.gov (United States)

    Saucan, Augustin-Alexandru; Li, Yunpeng; Coates, Mark

    2017-05-01

    In this paper we propose a Superpositional Marginalized δ-GLMB (SMδ-GLMB) filter for multi-target tracking and we provide bootstrap and particle flow particle filter implementations. Particle filter implementations of the marginalized δ-GLMB filter are computationally demanding. As a first contribution we show that for the specific case of superpositional observation models, a reduced complexity update step can be achieved by employing a superpositional change of variables. The resulting SMδ-GLMB filter can be readily implemented using the unscented Kalman filter or particle filtering methods. As a second contribution, we employ particle flow to produce a measurement-driven importance distribution that serves as a proposal in the SMδ-GLMB particle filter. In high-dimensional state systems or for highly- informative observations the generic particle filter often suffers from weight degeneracy or otherwise requires a prohibitively large number of particles. Particle flow avoids particle weight degeneracy by guiding particles to regions where the posterior is significant. Numerical simulations showcase the reduced complexity and improved performance of the bootstrap SMδ-GLMB filter with respect to the bootstrap Mδ-GLMB filter. The particle flow SMδ-GLMB filter further improves the accuracy of track estimates for highly informative measurements.

  16. Manipulation Robustness of Collaborative Filtering

    OpenAIRE

    Benjamin Van Roy; Xiang Yan

    2010-01-01

    A collaborative filtering system recommends to users products that similar users like. Collaborative filtering systems influence purchase decisions and hence have become targets of manipulation by unscrupulous vendors. We demonstrate that nearest neighbors algorithms, which are widely used in commercial systems, are highly susceptible to manipulation and introduce new collaborative filtering algorithms that are relatively robust.

  17. Popping the filter bubble

    OpenAIRE

    Hughes, Katie; Cronin, G; Welch, L

    2017-01-01

    So-called “fake news” is everywhere and is having a major impact on daily life from politics to education. The rapid growth of information and the numbers of people who can create it means that we need more sophisticated tools to process the news we receive. Join us to learn about different methods you can use to be your own fact checker and pop your filter bubble.

  18. Offsetting the Affective Filter

    Directory of Open Access Journals (Sweden)

    Barry Chametzky, PhD

    2017-06-01

    Full Text Available When forced to deal with a stressful, unfamiliar situation, how do people react? People are familiar, in a traditional setting, with sensory overload. But in an online environment, when learners are anxious, they exhibit different behaviors to help mediate their anxiety. Additionally, in an online environment, since visual clues are often lacking, how do these behaviors manifest themselves? People navigate stressful and/or unfamiliar situations by offsetting their affective filter.

  19. Filter Bank Fusion Frames

    OpenAIRE

    Chebira, Amina; Fickus, Matthew; Mixon, Dustin G.

    2010-01-01

    In this paper we characterize and construct novel oversampled filter banks implementing fusion frames. A fusion frame is a sequence of orthogonal projection operators whose sum can be inverted in a numerically stable way. When properly designed, fusion frames can provide redundant encodings of signals which are optimally robust against certain types of noise and erasures. However, up to this point, few implementable constructions of such frames were known; we show how to construct them using ...

  20. EVALUATION OF FILTERS FOR ENVISAT ASAR SPECKLE SUPPRESSION IN PASTURE AREA

    Directory of Open Access Journals (Sweden)

    X. Wang

    2012-07-01

    Full Text Available In order to quantify real time pasture biomass from SAR image, regression model between ground measurements of biomass and ENVISAT ASAR backscattering coefficient should be built up. An important prerequisite of valid and accurate regression model is accurate grass backscattering coefficient which, however, cannot be obtained when there is speckle. Speckle noise is the best known problem of SAR images because of the coherent nature of radar illumination imaging system. This study aims to choose better adaptive filter from NEST software to reduce speckle noise in homogeneous pasture area, with little regard to linear feature (e.g. edge between pasture and forest or point feature (e.g. pond, tree preservation. This paper presents the speckle suppression result of ENVISAT ASAR VV/VH images in pasture of Western Australia (WA using four built-in adaptive filters of the NEST software: Frost, Gamma Map, Lee, and Refined Lee filter. Two indices are usually used for evaluation of speckle suppression ability: ENL (Equivalent Number of Looks and SSI (Speckle Suppression Index. These two, however, are not reliable because sometimes they overestimate mean value. Therefore, apart from ENL and SSI, the authors also used a new index SMPI (Speckle Suppression and Mean Preservation Index. It was found that, Lee filter with window size 7×7 and Frost filter (damping factor = 2 with window size 5×5 gave the best performance for VV and VH polarization, respectively. The filtering, together with radiometric calibration and terrain correction, paves the way to extraction of accurate backscattering coefficient of grass in homogeneous pasture area in WA.

  1. Postseismic deformation in the El Asnam fault region (Algeria): Results from merged PS-InSAR and Small Baseline methods

    Science.gov (United States)

    Bouraoui, Seyfallah; Meghraoui, Mustapha; Doumaz, Fawzi

    2013-04-01

    We investigate the surface displacement along the 36-km-long and NE trending El-Asnam thrust fault (NW Algeria) responsible of two large earthquakes (Ms 6.7 in 1954 and Ms 7.3 in 1980) using Stamps/MTI advanced time series analysis of ERS SAR images acquired between 1997 and 2000. Previous leveling measurements of geodetic benchmarks conducted from 1986 to 1991 show 5.1 ± 1.9 mm/yr and 9.6 ± 1.4 mm/yr postseismic uplift rate of the northwestern block. The processed 9 SAR images (ERS1 and ERS2) are based on the combination of PS-SB using Stamps, the 3-arc/sec SRTM topographic data, and filtering in order to remove atmospheric artifacts and control the Doppler centroid difference.The semi-arid landscape of the El Asnam (nowadays Chlef) region provides favorable image coherency for interferometric SAR processing. The application of Persistent Scatterer InSAR (PS) and Small baseline (SB) approaches reveals significant surface changes across the fault zone. The earthquake fault area limits two distinct zones, with LOS values reaching 30.4 mm cumulative displacement corresponding to 16.2 mm(uplift) on the hanging block and -14.2 mm (subsidence) on the footwall block.We then extract the vertical and horizontal components (uplift and NNW-SSE shortening) from the LOS and obtain 0.6 mm/yr and 0.4 mm/yr, respectively. The elastic modeling on the homogeneous 1980 fault rupture illustrates the crustal deformation at depth. The cumulative postseismic and perhaps comparable interseismic deformation across this tectonic boundary may explain the frequent earthquake occurrence in this region. The InSAR Time Series analysis also shows LOS displacement on other parallel active faults (Bou Kadir fault and Tenes fault) NNW of the El Asnam fault. The inferred total rate of shortening across these faults and the Tell Atlas of Algeria reflects the level of active deformation along this section of the plate boundary in North Africa.

  2. Accelerating Spaceborne SAR Imaging Using Multiple CPU/GPU Deep Collaborative Computing

    National Research Council Canada - National Science Library

    Zhang, Fan; Li, Guojun; Li, Wei; Hu, Wei; Hu, Yuxin

    2016-01-01

    ...). However, the computing capability of CPU is ignored and underestimated. In this work, a new deep collaborative SAR imaging method based on multiple CPU/GPU is proposed to achieve real-time SAR imaging...

  3. Development of chemical inhibitors of the SARS coronavirus: viral helicase as a potential target.

    Science.gov (United States)

    Keum, Young-Sam; Jeong, Yong-Joo

    2012-11-15

    Severe acute respiratory syndrome (SARS) was the first pandemic in the 21st century to claim more than 700 lives worldwide. However, effective anti-SARS vaccines or medications are currently unavailable despite being desperately needed to adequately prepare for a possible SARS outbreak. SARS is caused by a novel coronavirus, and one of its components, a viral helicase, is emerging as a promising target for the development of chemical SARS inhibitors. In the following review, we describe the characterization, family classification, and kinetic movement mechanisms of the SARS coronavirus (SCV) helicase-nsP13. We also discuss the recent progress in the identification of novel chemical inhibitors of nsP13 in the context of our recent discovery of the strong inhibition of the SARS helicase by natural flavonoids, myricetin and scutellarein. These compounds will serve as important resources for the future development of anti-SARS medications. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. The potential of targeted antibody prophylaxis in SARS outbreak control: a mathematic analysis

    NARCIS (Netherlands)

    Bogaards, Johannes Antonie; Putter, Hein; Jan Weverling, Gerrit; ter Meulen, Jan; Goudsmit, Jaap

    2007-01-01

    BACKGROUND: Severe acute respiratory syndrome (SARS) coronavirus-like viruses continue to circulate in animal reservoirs. If new mutants of SARS coronavirus do initiate another epidemic, administration of prophylactic antibodies to risk groups may supplement the stringent isolation procedures that

  5. SAR image registration in absolute coordinates using GPS carrier phase position and velocity information

    Energy Technology Data Exchange (ETDEWEB)

    Burgett, S.; Meindl, M. [Sandia National Labs., Albuquerque, NM (United States). Aided Navigation and Remote Sensing Systems

    1994-09-01

    It is useful in a variety of military and commercial application to accurately register the position of synthetic aperture radar (SAR) imagery in absolute coordinates. The two basic SAR measurements, range and doppler, can be used to solve for the position of the SAR image. Imprecise knowledge of the SAR collection platform`s position and velocity vectors introduce errors in the range and doppler measurements and can cause the apparent location of the SAR image on the ground to be in error by tens of meters. Recent advances in carrier phase GPS techniques can provide an accurate description of the collection vehicle`s trajectory during the image formation process. In this paper, highly accurate carrier phase GPS trajectory information is used in conjunction with SAR imagery to demonstrate a technique for accurate registration of SAR images in WGS-84 coordinates. Flight test data will be presented that demonstrates SAR image registration errors of less than 4 meters.

  6. Digital SAR Mosaic and Elevation Map of the Greenland Ice Sheet, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Digital SAR Mosaic and Elevation Map of the Greenland Ice Sheet CD-ROM combines the most detailed synthetic aperture radar (SAR) image mosaic available with the...

  7. Digital SAR Mosaic and Elevation Map of the Greenland Ice Sheet

    Data.gov (United States)

    National Aeronautics and Space Administration — The Digital SAR Mosaic and Elevation Map of the Greenland Ice Sheet CD-ROM combines the most detailed synthetic aperture radar (SAR) image mosaic available with the...

  8. Flexible T/R Modules for Large-Aperture, Space-Based SAR Project

    Data.gov (United States)

    National Aeronautics and Space Administration — There is a need for electronically-steerable, space-deployable SAR antenna arrays which impose minimal weight burden on the vehicles that place them into orbit. SAR...

  9. The SARS-unique domain (SUD of SARS coronavirus contains two macrodomains that bind G-quadruplexes.

    Directory of Open Access Journals (Sweden)

    Jinzhi Tan

    2009-05-01

    Full Text Available Since the outbreak of severe acute respiratory syndrome (SARS in 2003, the three-dimensional structures of several of the replicase/transcriptase components of SARS coronavirus (SARS-CoV, the non-structural proteins (Nsps, have been determined. However, within the large Nsp3 (1922 amino-acid residues, the structure and function of the so-called SARS-unique domain (SUD have remained elusive. SUD occurs only in SARS-CoV and the highly related viruses found in certain bats, but is absent from all other coronaviruses. Therefore, it has been speculated that it may be involved in the extreme pathogenicity of SARS-CoV, compared to other coronaviruses, most of which cause only mild infections in humans. In order to help elucidate the function of the SUD, we have determined crystal structures of fragment 389-652 ("SUD(core" of Nsp3, which comprises 264 of the 338 residues of the domain. Both the monoclinic and triclinic crystal forms (2.2 and 2.8 A resolution, respectively revealed that SUD(core forms a homodimer. Each monomer consists of two subdomains, SUD-N and SUD-M, with a macrodomain fold similar to the SARS-CoV X-domain. However, in contrast to the latter, SUD fails to bind ADP-ribose, as determined by zone-interference gel electrophoresis. Instead, the entire SUD(core as well as its individual subdomains interact with oligonucleotides known to form G-quadruplexes. This includes oligodeoxy- as well as oligoribonucleotides. Mutations of selected lysine residues on the surface of the SUD-N subdomain lead to reduction of G-quadruplex binding, whereas mutations in the SUD-M subdomain abolish it. As there is no evidence for Nsp3 entering the nucleus of the host cell, the SARS-CoV genomic RNA or host-cell mRNA containing long G-stretches may be targets of SUD. The SARS-CoV genome is devoid of G-stretches longer than 5-6 nucleotides, but more extended G-stretches are found in the 3'-nontranslated regions of mRNAs coding for certain host-cell proteins

  10. SweepSAR: Beam-forming on Receive Using a Reflector-Phased Array Feed Combination for Spaceborne SAR

    Science.gov (United States)

    Freeman, A.; Krieger, G.; Rosen, P.; Younis, M.; Johnson, W. T. K.; Huber, S.; Jordan, R.; Moreira, A.

    2012-01-01

    In this paper, an alternative approach is described that is suited for longer wavelength SARs in particular, employing a large, deployable reflector antenna and a much simpler phased array feed. To illuminate a wide swath, a substantial fraction of the phased array feed is excited on transmit to sub-illuminate the reflector. Shorter transmit pulses are required than for conventional SAR. On receive, a much smaller portion of the phased array feed is used to collect the return echo, so that a greater portion of the reflector antenna area is used. The locus of the portion of the phased array used on receive is adjusted using an analog beam steering network, to 'sweep' the receive beam(s) across the illuminated swath, tracking the return echo. This is similar in some respects to the whiskbroom approach to optical sensors, hence the name: SweepSAR.SweepSAR has advantages over conventional SAR in that it requires less transmit power, and if the receive beam is narrow enough, it is relatively immune to range ambiguities. Compared to direct radiating arrays with digital beam- forming, it is much simpler to implement, uses currently available technologies, is better suited for longer wavelength systems, and does not require extremely high data rates or onboard processing.

  11. Polarimetric SAR interferometry applied to land ice: modeling

    DEFF Research Database (Denmark)

    Dall, Jørgen; Papathanassiou, Konstantinos; Skriver, Henning

    2004-01-01

    depths. The validity of the scattering models is examined using L-band polarimetric interferometric SAR data acquired with the EMISAR system over an ice cap located in the percolation zone of the Greenland ice sheet. Radar reflectors were deployed on the ice surface prior to the data acquisition in order......This paper introduces a few simple scattering models intended for the application of polarimetric SAR interfer-ometry to land ice. The principal aim is to eliminate the penetration bias hampering ice sheet elevation maps generated with single-channel SAR interferometry. The polarimetric coherent...... scattering models are similar to the oriented-volume model and the random-volume-over-ground model used in vegetation studies, but the ice models are adapted to the different geometry of land ice. Also, due to compaction, land ice is not uniform; a fact that must be taken into account for large penetration...

  12. Il monitoraggio degli spostamenti con Interferometria SAR Terrestre

    Directory of Open Access Journals (Sweden)

    Paolo Mazzanti

    2012-04-01

    Full Text Available Circa un anno fa l’autore del presente articolo è stato invitato a scrivere una nota sull’Interferometria SARTerrestre per una rivista internazionale specializzata sul monitoraggio geotecnico. A un anno di distanza ha ritenuto di interesse tradurre e aggiornare quel lavoro al fine di renderlo più facilmente fruibile alla comunità geomatica italiana.   Displacement monitoring by Terrestrial SAR Interferometry Remote sensing techniques are one of the main innovation in the field  of geotechnical and structural monitoring, since they are changing the philosophy from “contact” to “non-contact” monitoring. Over the last years Terrestrial SAR Interferometry (TInSAR has proven to be one of the most effective solutions for the fully remote and accurate monitoring of mm displacement.

  13. Pulse-based internal calibration of polarimetric SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Skou, Niels; Christensen, Erik Lintz

    1994-01-01

    Internal calibration greatly diminishes the dependence on calibration target deployment compared to external calibration. Therefore the Electromagnetics Institute (EMI) at the Technical University of Denmark (TUD) has equipped its polarimetric SAR, EMISAR, with several calibration loops and devel......Internal calibration greatly diminishes the dependence on calibration target deployment compared to external calibration. Therefore the Electromagnetics Institute (EMI) at the Technical University of Denmark (TUD) has equipped its polarimetric SAR, EMISAR, with several calibration loops...... and developed a procedure for calibrating the entire system except a few passive components which must be measured in the laboratory. The calibration procedure has great potential as it takes into account the SAR point target response (PTR) unlike most other internal calibration schemes. However, it requires...

  14. Metamaterial-Embedded Low SAR PIFA for Cellular Phone

    Science.gov (United States)

    Faruque, M. R. I.; Hossain, M. I.; Misran, N.; Singh, M.; Islam, M. T.

    2015-01-01

    A metamaterial-embedded planar inverted-F antenna (PIFA) is proposed in this study for cellular phone applications. A dual-band PIFA is designed to operate both GSM 900 MHz and DCS 1800 MHz. The ground plane of a conventional PIFA is modified using a planar one-dimensional metamaterial array. The investigation is performed using the Finite Integration Technique (FIT) of CST Microwave Studio. The performance of the developed antenna was measured in an anechoic chamber. The specific absorption rate (SAR) values are calculated considering two different holding positions: cheek and tilt. The SAR values are measured using COMOSAR measurement system. Good agreement is observed between the simulated and measured data. The results indicate that the proposed metamaterial-embedded antenna produces significantly lower SAR in the human head compared to the conventional PIFA. Moreover, the modified antenna substrate leads to slight improvement of the antenna performances. PMID:26599584

  15. Theory and measure of certain image norms in SAR

    Science.gov (United States)

    Raney, R. K.

    1984-01-01

    The principal properties of synthetic aperture radar SAR imagery of point and distributed objects are summarized. Against this background, the response of a SAR (Synthetic Aperture Radar) to the moving surface of the sea is considered. Certain conclusions are drawn as to the mechanism of interaction between microwaves and the sea surface. Focus and speckle spectral tests may be used on selected SAR imagery for areas of the ocean. The fine structure of the sea imagery is sensitive to processor focus and adjustment. The ocean reflectivity mechanism must include point like scatterers of sufficient radar cross section to dominate the return from certain individual resolution elements. Both specular and diffuse scattering mechanisms are observed together, to varying degree. The effect is sea state dependent. Several experiments are proposed based on imaging theory that could assist in the investigation of reflectivity mechanisms.

  16. High Efficient Universal Buck Boost Solar Array Regulator SAR Module

    Science.gov (United States)

    Kimmelmann, Stefan; Knorr, Wolfgang

    2014-08-01

    The high efficient universal Buck Boost Solar Array Regulator (SAR) module concept is applicable for a wide range of input and output voltages. The single point failure tolerant SAR module contains 3 power converters for the transfer of the SAR power to the battery dominated power bus. The converters are operating parallel in a 2 out of 3 redundancy and are driven by two different controllers. The output power of one module can be adjusted up to 1KW depending on the requirements. The maximum power point tracker (MPPT) is placed on a separate small printed circuit board and can be used if no external tracker signal is delivered. Depending on the mode and load conditions an efficiency of more than 97% is achievable. The stable control performance is achieved by implementing the magnetic current sense detection. The sensed power coil current is used in Buck and Boost control mode.

  17. SAR image segmentation using MPM and constrained stochastic relaxation

    Science.gov (United States)

    Zhao, Huiyan; Cao, Yongfeng; Yang, Wen

    2005-10-01

    A segmentation method using maximization of the Posterior marginals (MPM) and constrained stochastic relaxation (CSR) for SAR images is proposed. This method improves the regularity of MPM based segmentation result by introducing CSR. Multi-Level Logistic (MLL) model is used for the underlying label image to introduce regularity prior of segmentation. Gamma distribution is used for SAR intensity data. The hyper parameters of MLL model are supposed to be known a priori. This method is an iterative scheme consists of two alternating steps: to approximate the MPM estimation of the pixel class labels and to estimate gamma distribution parameters. The weight of the prior energy in goal energy function is increased slowly versus the increasing iteration times until certain number of iteration has finished. The segmentation results for synthetic and real SAR images show that the proposed method has a good performance.

  18. Investigation of vegetation with multifrequency and multipolarization SAR systems

    Science.gov (United States)

    Winter, Rudolf; Roth, Achim; Bayer, Thomas

    1990-05-01

    Investigations of vegetation is conducted by synergism of different types of digital image data and models. As a standard application, satellite images are digitally coregistered with existant topographical data and stored in the Geographic Information Systems (GIS). The usefulness of multiparametric SAR (Synthetic Aperture Radar) data for vegetation mapping is discussed. The multifrequency aspects requires precise geocoding. Different application fields with recent results are discussed: forest investigations with SIR (Spaceborne Imaging Radar)-B data in the southern Rhine valley ; extraction of landuse categories in landscape units using two geocoded Seasat-SAR scenes in the area of Bonn; relief effects on image gray values in geocoded Seasat-SAR images; the concept of a remote sensing data base for ecological applications.

  19. Metamaterial-Embedded Low SAR PIFA for Cellular Phone.

    Science.gov (United States)

    Faruque, M R I; Hossain, M I; Misran, N; Singh, M; Islam, M T

    2015-01-01

    A metamaterial-embedded planar inverted-F antenna (PIFA) is proposed in this study for cellular phone applications. A dual-band PIFA is designed to operate both GSM 900 MHz and DCS 1800 MHz. The ground plane of a conventional PIFA is modified using a planar one-dimensional metamaterial array. The investigation is performed using the Finite Integration Technique (FIT) of CST Microwave Studio. The performance of the developed antenna was measured in an anechoic chamber. The specific absorption rate (SAR) values are calculated considering two different holding positions: cheek and tilt. The SAR values are measured using COMOSAR measurement system. Good agreement is observed between the simulated and measured data. The results indicate that the proposed metamaterial-embedded antenna produces significantly lower SAR in the human head compared to the conventional PIFA. Moreover, the modified antenna substrate leads to slight improvement of the antenna performances.

  20. THz-SAR Vibrating Target Imaging via the Bayesian Method

    Directory of Open Access Journals (Sweden)

    Bin Deng

    2017-01-01

    Full Text Available Target vibration bears important information for target recognition, and terahertz, due to significant micro-Doppler effects, has strong advantages for remotely sensing vibrations. In this paper, the imaging characteristics of vibrating targets with THz-SAR are at first analyzed. An improved algorithm based on an excellent Bayesian approach, that is, the expansion-compression variance-component (ExCoV method, has been proposed for reconstructing scattering coefficients of vibrating targets, which provides more robust and efficient initialization and overcomes the deficiencies of sidelobes as well as artifacts arising from the traditional correlation method. A real vibration measurement experiment of idle cars was performed to validate the range model. Simulated SAR data of vibrating targets and a tank model in a real background in 220 GHz show good performance at low SNR. Rapidly evolving high-power terahertz devices will offer viable THz-SAR application at a distance of several kilometers.

  1. Metamaterial-Embedded Low SAR PIFA for Cellular Phone.

    Directory of Open Access Journals (Sweden)

    M R I Faruque

    Full Text Available A metamaterial-embedded planar inverted-F antenna (PIFA is proposed in this study for cellular phone applications. A dual-band PIFA is designed to operate both GSM 900 MHz and DCS 1800 MHz. The ground plane of a conventional PIFA is modified using a planar one-dimensional metamaterial array. The investigation is performed using the Finite Integration Technique (FIT of CST Microwave Studio. The performance of the developed antenna was measured in an anechoic chamber. The specific absorption rate (SAR values are calculated considering two different holding positions: cheek and tilt. The SAR values are measured using COMOSAR measurement system. Good agreement is observed between the simulated and measured data. The results indicate that the proposed metamaterial-embedded antenna produces significantly lower SAR in the human head compared to the conventional PIFA. Moreover, the modified antenna substrate leads to slight improvement of the antenna performances.

  2. Exploitation of satellite optical and SAR data for public work studies

    Science.gov (United States)

    Ioannidis, Charalabos; Soile, Sofia; Stamos, Athanassios; Vassilaki, Dimitra; Maltezos, Evangelos; Verykokou, Styliani

    2015-06-01

    This paper studies the use of high resolution satellite optical and SAR images for 1:5,000 mapping production, which is essential for public work and environmental impact assessment studies. The images were used for the extraction of DEMs and their "fit for purpose" use was investigated, through the examination of parameters like accuracy, reliability and performance of morphological features. Orthoimages from satellite optical images using the produced DEMs with or without breaklines were produced. An application was developed on Antiparos island, a Greek island with irregular terrain. The data includes: (a) a triplet of Pleiades (1A, tri-stereo) satellite images, with a resolution of 0.5m, (b) a TanDEM-X Intermediate DEM, a preliminary version of the forthcoming TanDEM-X global DEM, and (c) an accurate DEM produced from the Greek National Cadastre & Mapping Agency S.A. was used as the reference DEM. The georeferencing of the optical images was computed using GCPs which were measured with GNSS. DEMs were extracted using all the possible combinations of the images triplet using automated image matching without any filtering or editing and were evaluated using the reference DEM. The combination of images which yielded the best DEM was then used to manually editing 3D points and collecting breaklines in order to produce a better DEM, which was also evaluated using various statistical measures and geo-morphological features. Orthoimages were created and evaluated using DEMs from optical and SAR data. A discussion about the use of the computed mapping products for the various stages of the public work studies is included.

  3. A 12-bit SAR ADC integrated on a multichannel silicon drift detector readout IC

    Energy Technology Data Exchange (ETDEWEB)

    Schembari, F., E-mail: filippo.schembari@polimi.it [Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, via Golgi 40, 20133 Milano (Italy); INFN, Sezione di Milano, via Celoria 16, 20133 Milano (Italy); Bellotti, G.; Fiorini, C. [Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, via Golgi 40, 20133 Milano (Italy); INFN, Sezione di Milano, via Celoria 16, 20133 Milano (Italy)

    2016-07-11

    A 12-bit analog-to-digital converter (ADC) addressed to Silicon-Drift Detectors (SDDs) multichannel readout ASICs for X- and gamma-ray applications is presented. Aiming at digitizing output multiplexed data from the upstream analog filters banks, the converter must ensure 11-bit accuracy and a sampling frequency of about 5 MS/s. The ADC architecture is the charge-redistribution (CR) successive-approximation register (SAR). A fully differential topology has also been chosen for better rejection of common-mode noise and disturbances. The internal DAC is made of binary-scaled capacitors, whose bottom plates are switched by the SAR logic to perform the binary search of the analog input value by means of the monotonic switching scheme. The A/D converter is integrated on SFERA, a multichannel ASIC fabricated in a standard CMOS 0.35 μm 3.3 V technology and it occupies an area of 0.42 mm{sup 2}. Simulated static performance shows monotonicity over the whole input–output characteristic. The description of the circuit topology and of inner blocks architectures together with the experimental characterization is here presented. - Highlights: • X- and γ-ray spectroscopy front-ends need to readout a high number of detectors. • Design efforts are increasingly oriented to compact and low-power ASICs. • A possible solution is the on-chip integration of the analog-to-digital converter. • A 12-bit CR successive-approximation-register ADC has been developed. • It is a suitable candidate as the digitizer to be integrated in multichannel ASICs.

  4. Monolithic integrated filters - An overview

    Science.gov (United States)

    Entenmann, W.

    1981-04-01

    An overview of the state of the art in monolithic integrated filter design is given. The close mutual influence of technology and network theory and the continuing development of filter designs with higher integration, higher reliability, lower costs and lower space demands are examined. The fundamental concepts of circuit theory and MOS technology are described and the principal construction of the components of the three major classes of MOS filter circuits examined, namely the change-transfer filter, the switched-capacitor filter and the digital filter. The most important properties, such as the periodicity of the spectra, the impulse response, as well as recursive, nonrecursive, linear and minimal phase filters are covered. Some methods for calculating filter circuits by using classical reactance filter synthesis with the aid of suitable transformations from analog time-continuous reference circuits are discussed. The obtainable signal frequency ranges and filter grades are shown in order to compare the efficiency and operating range of monolithic integrated filter circuits with each other and with other concepts.

  5. Compact SAR and Small Satellite Solutions for Earth Observation

    Science.gov (United States)

    LaRosa, M.; L'Abbate, M.

    2016-12-01

    Requirements for near and short term mission applications (Observation and Reconnaissance, SIGINT, Early Warning, Meteorology,..) are increasingly calling for spacecraft operational responsiveness, flexible configuration, lower cost satellite constellations and flying formations, to improve both the temporal performance of observation systems (revisit, response time) and the remote sensing techniques (distributed sensors, arrays, cooperative sensors). In answer to these users' needs, leading actors in Space Systems for EO are involved in development of Small and Microsatellites solutions. Thales Alenia Space (TAS) has started the "COMPACT-SAR" project to develop a SAR satellite characterized by low cost and reduced mass while providing, at the same time, high image quality in terms of resolution, swath size, and radiometric performance. Compact SAR will embark a X-band SAR based on a deployable reflector antenna fed by an active phased array feed. This concept allows high performance, providing capability of electronic beam steering both in azimuth and elevation planes, improving operational performance over a purely mechanically steered SAR system. Instrument provides both STRIPMAP and SPOTLIGHT modes, and thanks to very high gain antenna, can also provide a real maritime surveillance mode based on a patented Low PRF radar mode. Further developments are in progress considering missions based on Microsatellites technology, which can provide effective solutions for different user needs, such as Operational responsiveness, low cost constellations, distributed observation concept, flying formations, and can be conceived for applications in the field of Observation, Atmosphere sensing, Intelligence, Surveillance, Reconnaissance (ISR), Signal Intelligence. To satisfy these requirements, flexibility of small platforms is a key driver and especially new miniaturization technologies able to optimize the performance. An overview new micros-satellite (based on NIMBUS

  6. Mapping Regional Inundation with Spaceborne L-Band SAR

    Directory of Open Access Journals (Sweden)

    Bruce Chapman

    2015-04-01

    Full Text Available Shortly after the launch of ALOS PALSAR L-band SAR by the Japan Space Exploration Agency (JAXA, a program to develop an Earth Science Data Record (ESDR for inundated wetlands was funded by NASA. Using established methodologies, extensive multi-temporal L-band ALOS ScanSAR data acquired bi-monthly by the PALSAR instrument onboard ALOS were used to classify the inundation state for South America for delivery as a component of this Inundated Wetlands ESDR (IW-ESDR and in collaboration with JAXA’s ALOS Kyoto and Carbon Initiative science programme. We describe these methodologies and the final classification of the inundation state, then compared this with results derived from dual-season data acquired by the JERS-1 L-band SAR mission in 1995 and 1996, as well as with estimates of surface water extent measured globally every 10 days by coarser resolution sensors. Good correspondence was found when comparing open water extent classified from multi-temporal ALOS ScanSAR data with surface water fraction identified from coarse resolution sensors, except in those regions where there may be differences in sensitivity to widespread and shallow seasonal flooding event, or in areas that could be excluded through use of a continental-scale inundatable mask. It was found that the ALOS ScanSAR classification of inundated vegetation was relatively insensitive to inundated herbaceous vegetation. Inundation dynamics were examined using the multi-temporal ALOS ScanSAR acquisitions over the Pacaya-Samiria and surrounding areas in the Peruvian Amazon.

  7. Coping with future epidemics: Tai chi practice as an overcoming strategy used by survivors of severe acute respiratory syndrome (SARS) in post-SARS Hong Kong.

    Science.gov (United States)

    Siu, Judy Yuen-Man

    2016-06-01

    Although SARS had been with a controversial topic for a decade at the time of this study, numerous SARS survivors had not yet physically, psychologically or socially recovered from the aftermath of SARS. Among chronically ill patients, the use of complementary and alternative medicine (CAM) is reported to be widespread. However, extremely little is known about the use of CAM by SARS survivors in the post-SARS period and even less is known about how the use of CAM is related to the unpleasant social and medical-treatment experiences of SARS survivors, their eagerness to re-establish social networks, and their awareness to prepare for future epidemics. To investigate the motivations for practising tai chi among SARS survivors in post-SARS Hong Kong. Using a qualitative approach, I conducted individual semi-structured interviews with 35 SARS survivors, who were purposively sampled from a tai chi class of a SARS-patient self-help group in Hong Kong. Health concerns and social experiences motivated the participants to practise tai chi in post-SARS Hong Kong. Experiencing health deterioration in relation to SARS-associated sequelae, coping with unpleasant experiences during follow-up biomedical treatments, a desire to regain an active role in recovery and rehabilitation, overcoming SARS-associated stigmas by establishing a new social network and preparing for potential future stigmatization and discrimination were the key motivators for them. The participants practised tai chi not only because they sought to improve their health but also because it provided a crucial social function and meaning to them. © 2014 John Wiley & Sons Ltd.

  8. Wiener filter for filtered back projection in digital breast tomosynthesis

    Science.gov (United States)

    Wang, Xinying; Mainprize, James G.; Wu, Gang; Yaffe, Martin J.

    2012-03-01

    Conventional filtered back projection (FBP) reconstruction for digital breast tomosynthesis (DBT) can suffer from a low signal to noise ratio. Because of the strong amplification by the reconstruction filters (ramp, apodization and slice thickness), noise at high spatial frequencies can be greatly increased. Image enhancement by Wiener filtering is investigated as a possible method to improve image quality. A neighborhood wavelet coefficient window technique is used to estimate the noise content of projection images and a Wiener filter is applied to the projection images. The neighborhood wavelet coefficient window is a non-linear technique, which may cause the Wiener filters estimated before and after the application of the reconstruction filters to be different. Image quality of a FBP reconstruction with and without Wiener filtering is investigated using a Fourier-based observer detectability metric ( d' ) for evaluation. Simulations of tomosynthesis are performed in both homogeneous and anatomic textured backgrounds containing lowcontrast masses or small microcalcifications. Initial results suggest that improvements in detectability can be achieved when the Wiener filter is applied, especially when the Wiener filter is estimated for the reconstruction filtered projections.

  9. Scattering Mechanism Extraction by a Modified Cloude-Pottier Decomposition for Dual Polarization SAR

    Directory of Open Access Journals (Sweden)

    Kefeng Ji

    2015-06-01

    Full Text Available Dual polarization is a typical operational mode of polarimetric synthetic aperture radar (SAR. However, few studies have considered the scattering mechanism extraction of dual-polarization SARs. A modified Cloude-Pottier decomposition is proposed to investigate the performance of the scattering mechanism extraction of dual-polarization SARs. It is theoretically demonstrated that only HH-VV SAR can discriminate the three canonical scattering mechanisms from an isotropic surface, horizontal dipole, and isotropic dihedral. Various experiments are conducted using 21 scenes from real datasets acquired by AIRSAR, Convair-580 SAR, EMISAR, E-SAR, Pi-SAR, and RADARSAT-2. Division of the dual-polarization H-α plane is experimentally obtained. The lack of cross-polarization induces the diffusion of scattering mechanisms and their overlap in the HH-VV H-α plane. However, the performance of HH-VV SAR for extracting scattering mechanisms is acceptable. Thus, HH-VV SAR is a suitable alternative to full-polarization SAR in certain cases. Meanwhile, the extraction performance of the other two dual-polarization SARs is badly degraded due to the lack of co-polarization. Therefore, HH-HV and HV-VV SARs cannot effectively extract the scattering mechanisms in the H-α plane.

  10. Integrating interferometric SAR data with levelling measurements of land subsidence using geostatistics

    NARCIS (Netherlands)

    Zhou, Y.; Stein, A.; Molenaar, M.

    2003-01-01

    Differential Synthetic Aperture Radar (SAR) interferometric (D-InSAR) data of ground surface deformation are affected by several error sources associated with image acquisitions and data processing. In this paper, we study the use of D-InSAR for quantifying land subsidence due to groundwater

  11. Detecting settlement expansion in South Africa using a hyper-temporal SAR change detection approach

    CSIR Research Space (South Africa)

    Kleynhans, W

    2015-10-01

    Full Text Available Recent times have seen a significant increase in the amount of readily available SAR data, with many current and historic SAR data holdings now adopting an open distribution policy. As more regular SAR observations are becoming available, the use...

  12. A Support Group for Home-Quarantined College Students Exposed to SARS: Learning from Practice

    Science.gov (United States)

    Pan, Peter J. D.; Chang, Shih-Hua; Yu, Yen-Yen

    2005-01-01

    This article is an initial description of a meaningful and valuable clinical experience in interacting with SARS home-quarantined college students in a support group in Taiwan. Information about SARS and home quarantine, the tasks of the Counseling Centers and group work after the SARS outbreak, the support group for home-quarantined members, the…

  13. Impact of Severe Acute Respiratory Syndrome (SARS Outbreaks on the Use of Emergency Department Medical Resources

    Directory of Open Access Journals (Sweden)

    Chien-Cheng Huang

    2005-06-01

    Conclusion: The SARS outbreak did not eliminate the need of critically ill patients for advanced medical support. However, besides an overall decrease in patient numbers, the SARS epidemic markedly altered demographic information, clinical characteristics, and the use of medical services by adult patients in the ED of a SARS-dedicated hospital.

  14. Microstrip antenna for polarimetric C-band SAR

    DEFF Research Database (Denmark)

    Granholm, Johan; Woelders, Kim; Dich, Mikael

    1994-01-01

    The paper outlines the design and the measured performance of a 224-element dual-linearly polarized microstrip array antenna with low cross-polarization. The array is currently being flown on the Danish high-resolution polarimetric C-band synthetic aperture radar (SAR)......The paper outlines the design and the measured performance of a 224-element dual-linearly polarized microstrip array antenna with low cross-polarization. The array is currently being flown on the Danish high-resolution polarimetric C-band synthetic aperture radar (SAR)...

  15. SAR image enhancement via post-correlation signal processing

    Science.gov (United States)

    Matthews, N. D.; Kaupp, V. H.; Waite, W. P.; Macdonald, H. C.

    1984-01-01

    Seventeen interpreters ranked sets of computer-generated radar imagery to assess the value of post-correlation processing on the interpretability of SAR (synthetic aperture radar) imagery. The post-correlation processing evaluated amounts to a nonlinear mapping of the signal exiting a digital correlator and allows full use of signal bandwidth for improving the spatial resolution or for noise reduction. The results indicate that it is reasonable to hypothesize an optimal SAR presentation format for specific applications even though this study was too limited to be specific.

  16. Software For Tie-Point Registration Of SAR Data

    Science.gov (United States)

    Rignot, Eric; Dubois, Pascale; Okonek, Sharon; Van Zyl, Jacob; Burnette, Fred; Borgeaud, Maurice

    1995-01-01

    SAR-REG software package registers synthetic-aperture-radar (SAR) image data to common reference frame based on manual tie-pointing. Image data can be in binary, integer, floating-point, or AIRSAR compressed format. For example, with map of soil characteristics, vegetation map, digital elevation map, or SPOT multispectral image, as long as user can generate binary image to be used by tie-pointing routine and data are available in one of the previously mentioned formats. Written in FORTRAN 77.

  17. MERS, SARS and other coronaviruses as causes of pneumonia.

    Science.gov (United States)

    Yin, Yudong; Wunderink, Richard G

    2018-02-01

    Human coronaviruses (HCoVs) have been considered to be relatively harmless respiratory pathogens in the past. However, after the outbreak of the severe acute respiratory syndrome (SARS) and emergence of the Middle East respiratory syndrome (MERS), HCoVs have received worldwide attention as important pathogens in respiratory tract infection. This review focuses on the epidemiology, pathogenesis and clinical characteristics among SARS-coronaviruses (CoV), MERS-CoV and other HCoV infections. © 2017 Asian Pacific Society of Respirology.

  18. Picture processing of SAR L-band imagery

    Science.gov (United States)

    Bryan, M. L.; Stromberg, W. D.; Farr, T.

    1977-01-01

    Data digitization and thresholding are applied to two scenes - sea ice and fresh-water lakes - to define the possible uses of automatic picture processing of uncalibrated SAR L-band imagery. It is shown that certain types of features, those which have constant returns which are also very high or very low in intensity can be effectively studied using simple automatic picture processing techniques applied to uncalibrated radar data. In areas which are generally inaccessible or in which monitoring of the changes of some types of earth surfaces are required, the uncalibrated SAR data can provide valuable inputs for modeling and mapping purposes.

  19. Retrieval of Aboveground Biomass Using Multi-Frequency SAR

    Science.gov (United States)

    Stelmaszczuk-Gorska, Martyna; Thiel, Christian; Schmullius, Christiane

    2016-08-01

    The objective of this study was to investigate above-ground biomass (AGB) estimation in forests by combining multi-frequency Synthetic Aperture Radar (SAR) L-band and C-band data. An area of Siberian boreal forest was selected for this study. The results demonstrated that relatively high estimation accuracy can be obtained at the spatial resolution of 0.5 ha using the L- and C-band SAR backscatter. Overall, the AGB estimation error was calculated to be approximately 24 t ha-1 using the Random Forests machine learning algorithm.

  20. TerraSAR-X Capabilities in Polar Regions

    OpenAIRE

    Floricioiu, Dana; Gottwald, Manfred; Diedrich, Erhard; Roth, Achim; Eineder, Michael

    2008-01-01

    DLR participates in a coordinated plan established by the space agencies for the optimum use of SAR acquisitions over the Artic and Antarctica for the remaining period of IPY and beyond. Due to the specific advantages of the X-band in respect to snow and ice properties and the high spatial resolution of the data, the contribution of TerraSAR-X focuses on topics like mapping of seasonal snow cover at high latitudes, ice sheet velocity, velocity fields of slow and fast moving glaciers, permafro...

  1. The Danish real-time SAR processor: first results

    DEFF Research Database (Denmark)

    Dall, Jørgen; Jørgensen, Jørn Hjelm; Netterstrøm, Anders

    1993-01-01

    A real-time processor (RTP) for the Danish airborne Synthetic Aperture Radar (SAR) has been designed and constructed at the Electromagnetics Institute. The implementation was completed in mid 1992, and since then the RTP has been operated successfully on several test and demonstration flights....... The processor is capable of focusing the entire swath of the raw SAR data into full resolution, and depending on the choice made by the on-board operator, either a high resolution one-look zoom image or a spatially multilooked overview image is displayed. After a brief design review, the paper addresses various...

  2. Quartz red TL SAR equivalent dose overestimation for Chinese loess

    DEFF Research Database (Denmark)

    Lai, Z.P.; Murray, A.S.; Bailey, R.M.

    2006-01-01

    For the red TL of quartz extracted from Chinese loess, the single-aliquot regenerative-dose (SAR) procedure overestimates the known laboratory doses in dose recovery test. The overestimation is the result of the first heating during the measurement of natural TL signal causing a sensitivity...... reduction, which is not corrected for using a SAR protocol. The SARA procedure was used to measure the sensitivity change. Using this as a correction factor is tested by comparison with the quartz optically stimulated luminiscence (OSL) equivalent dose. SARA is also employed to determine the residual level...

  3. Crop Classification Using Short-Revisit Multitemporal SAR Data

    DEFF Research Database (Denmark)

    Skriver, Henning; Mattia, Francesco; Satalino, Giuseppe

    2011-01-01

    time acquired by the German ESAR system during the ESA-campaign, AgriSAR 2006, has been used to assess the performance of different polarization modes for crop classification. Both C-and L-band SAR data were acquired over the Demmin agricultural test site in North Eastern Germany on a weekly basis......, and that cross-polarized backscatter produces the best results, with errors down to 3%–6% at the two frequencies. There is a trade-off between the polarimetric information and the multitemporal information, where the best overall results are obtained using the multitemporal information. If only a few...

  4. Airborne Multi-Band SAR in the Arctic

    Science.gov (United States)

    Gardner, J. M.; Brozena, J. M.; Liang, R.; Ball, D.; Holt, B.; Thomson, J.

    2016-12-01

    As one component of the Office of Naval Research supported Sea State Departmental Research Initiative during October of 2015 the Naval Research Laboratory flew an ultrawide-band, low-frequency, polarimetric SAR over the southward advancing sea ice in Beaufort Sea. The flights were coordinated with the research team aboard the R/V Sikuliaq working near and in the advancing pack ice. The majority of the SAR data were collected with the L-Band sensor (1000-1500 MHz) from an altitude of 10,000', providing a useful swath 6 km wide with 75o and 25 o angles of incidence at the inner and outer edge of the swath respectively. Some data were also collected with the P-Band SAR (215-915 MHz). The extremely large bandwidths allowed for formation of image pixels as small as 30 cm, however, we selected 60 cm pixel size to reduce image speckle. The separate polarimetric images are calibrated to one pixel to allow for calculations such as polarimetric decompositions that require the images to be well aligned. Both frequencies are useful particularly for the detection of ridges and areas of deformed ice. There are advantages and disadvantages to airborne SAR imagery compared to satellites. The chief advantages being the enormous allowable bandwidth leading to very fine range resolution, and the ability to fly arbitrary trajectories on demand. The latter permits specific areas to be imaged at a given time with a specified illumination direction. An area can even be illuminated from all directions by flying a circular trajectory around the target area. This captures ice features that are sensitive to illumination direction such as cracks, sastrugi orientation, and ridges. The disadvantages include variation of intensity across the swath with range and incidence angle. In addition to the SAR data, we collected photogrammetric imagery from a DSS-439, scanning lidar from a Riegl Q560 and surface brightness temperatures from a KT-19. However, since all of these sensors are nadir pointing

  5. Superconducting notch filter

    Energy Technology Data Exchange (ETDEWEB)

    Pang, C S; Falco, C M; Kampwirth, R T; Schuller, I K; Hudak, J J; Anastasio, T A

    1979-01-01

    Results of a preliminary investigation of a superconducting notch filter for possible application in the 2 to 30 MHz high frequency (HF) communication band are presented. The circuit was successfully implemented using planar geometry so that closed cycle refrigeration could be used to cool circuits fabricated from high T/sub c/ Nb/sub 3/Sn or Nb/sub 3/Ge thin films. In the present design, circuit Q's of about 2 x 10/sup 3/ were obtained with 50-ohm source and output impedance. (TFD)

  6. Spindoktorer et politisk filter

    OpenAIRE

    Talic, Elvedin; Bernt, Rune; Mortensen, Mass Holmegård

    2015-01-01

    Through the TV and other media, many rumors about what a spin-doctor does and the nature of his services have spread. We would like to clarify the function; role and influence the spin-doctor have on Danish politics. We will look specifically at the relationship of power between the Ministers and spin-doctors, and the spin-doctors and media, as some believe that the spin-doctor sometimes will rise to power. We will also take look at the filter function between spin-doctors and media, as it is...

  7. Advances in Collaborative Filtering

    Science.gov (United States)

    Koren, Yehuda; Bell, Robert

    The collaborative filtering (CF) approach to recommenders has recently enjoyed much interest and progress. The fact that it played a central role within the recently completed Netflix competition has contributed to its popularity. This chapter surveys the recent progress in the field. Matrix factorization techniques, which became a first choice for implementing CF, are described together with recent innovations. We also describe several extensions that bring competitive accuracy into neighborhood methods, which used to dominate the field. The chapter demonstrates how to utilize temporal models and implicit feedback to extend models accuracy. In passing, we include detailed descriptions of some the central methods developed for tackling the challenge of the Netflix Prize competition.

  8. Multilevel ensemble Kalman filtering

    KAUST Repository

    Hoel, Hakon

    2016-06-14

    This work embeds a multilevel Monte Carlo sampling strategy into the Monte Carlo step of the ensemble Kalman filter (EnKF) in the setting of finite dimensional signal evolution and noisy discrete-time observations. The signal dynamics is assumed to be governed by a stochastic differential equation (SDE), and a hierarchy of time grids is introduced for multilevel numerical integration of that SDE. The resulting multilevel EnKF is proved to asymptotically outperform EnKF in terms of computational cost versus approximation accuracy. The theoretical results are illustrated numerically.

  9. Charcoal filter testing

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, J. [Nuclear Regulatory Commission, Washington, DC (United States)

    1997-08-01

    In this very brief, informal presentation, a representative of the US Nuclear Regulatory Commission outlines some problems with charcoal filter testing procedures and actions being taken to correct the problems. Two primary concerns are addressed: (1) the process to find the test method is confusing, and (2) the requirements of the reference test procedures result in condensation on the charcoal and causes the test to fail. To address these problems, emergency technical specifications were processed for three nuclear plants. A generic or an administrative letter is proposed as a more permanent solution. 1 fig.

  10. The optimum sunglass filter?

    Science.gov (United States)

    Soederberg, Per G.; Michael, Ralph; Ayala, Marcelo; Wu, Jiangmei; Loefgren, Stefan; Merriam, John; Chen, Enping

    1999-06-01

    It is concluded that sunglasses shall block UVR and toxic blue light, allow transmittance of signal light and bring luminous intensity behind the filters to a comfortable level. It was found that some commercially available sunglasses, apart from one pair of photochromatic dark state lenses tested, block ultraviolet radiation (UVR) adequately. Further, it was found that it is possible to block the toxic blue radiation without interfering substantially on blue signal light perception. However, none of the sunglasses tested blocked the toxic blue light enough.

  11. Digital Filters for Low Frequency Equalization

    DEFF Research Database (Denmark)

    Tyril, Marni; Abildgaard, J.; Rubak, Per

    2001-01-01

    Digital filters with high resolution in the low-frequency range are studied. Specifically, for a given computational power, traditional IIR filters are compared with warped FIR filters, warped IIR filters, and modified warped FIR filters termed warped individual z FIR filters (WizFIR). The results...

  12. High flow ceramic pot filters.

    Science.gov (United States)

    van Halem, D; van der Laan, H; Soppe, A I A; Heijman, S G J

    2017-11-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6-19 L h-1), but initial LRVs for E. coli of high flow filters was slightly lower than for regular ceramic pot filters. This disadvantage was, however, only temporarily as the clogging in high flow filters had a positive effect on the LRV for E. coli (from below 1 to 2-3 after clogging). Therefore, it can be carefully concluded that regular ceramic pot filters perform better initially, but after clogging, the high flow filters have a higher flow rate as well as a higher LRV for E. coli. To improve the initial performance of new high flow filters, it is recommended to further utilize residence time of the water in the receptacle, since additional E. coli inactivation was observed during overnight storage. Although a relationship was observed between flow rate and LRV of MS2 bacteriophages, both regular and high flow filters were unable to reach over 2 LRV. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. From Microwave Filter to Digital Filter and Back Again

    DEFF Research Database (Denmark)

    Dalby, Arne Brejning

    1989-01-01

    A new very simple state variable flow graph representation for interdigital transmission line bandpass filters is presented, which has led to two important results: 1) A new type of digital filter with properties, that surpass the properties of most other (all pole) digital filtertypes. 2......) The study of the new digital filtertype has led to design formulas for interdigital transmission line filters that are very simple compared to the hitherto known formulas. The accuracy is the same or better....

  14. Feature-based fusion of TomoSAR point clouds from multi-view TerraSAR-X data stacks

    OpenAIRE

    Wang, Yuanyuan; Zhu, Xiao Xiang

    2013-01-01

    This article presents a technique of fusing point clouds from multiple view angles generated using synthetic aperture radar (SAR) tomography. Using TerraSAR-X high resolution spotlight data stacks, one such point has a population of about 2×107 points, with a density of around 10^6 points / km2. Such large point population leads to a high computational cost while doing the fusion in 3D space. Therefore, we introduce a feature-based unsupervised technique for point clouds fusion by detectin...

  15. DSP Control of Line Hybrid Active Filter

    DEFF Research Database (Denmark)

    Dan, Stan George; Benjamin, Doniga Daniel; Magureanu, R.

    2005-01-01

    Active Power Filters have been intensively explored in the past decade. Hybrid active filters inherit the efficiency of passive filters and the improved performance of active filters, and thus constitute a viable improved approach for harmonic compensation. In this paper a parallel hybrid filter ...... active filter. Simulation and experimental results obtained in laboratory confirmed the validity and effectiveness of the control.......Active Power Filters have been intensively explored in the past decade. Hybrid active filters inherit the efficiency of passive filters and the improved performance of active filters, and thus constitute a viable improved approach for harmonic compensation. In this paper a parallel hybrid filter...... is studied for current harmonic compensation. The hybrid filter is formed by a single tuned Le filter and a small-rated power active filter, which are directly connected in series without any matching transformer. Thus the required rating of the active filter is much smaller than a conventional standalone...

  16. Coupling GB-SAR and visual photography for 3D modelling of an Alpine glacier surface kinematics

    Science.gov (United States)

    Dematteis, Niccolò; Luzi, Guido; Giordan, Daniele; Zucca, Francesco; Allasia, Paolo

    2017-04-01

    We present the 3-dimensional modelling of a glacier kinematics, obtained by coupling the results of two monitoring campaigns, simultaneously collecting data from two different and independent remote sensing devices, focused on the surface deformation of the Planpincieux glacier, on the Italian side of the Mont Blanc massif. The analysed period lasted 25 days and occurred in correspondence of the beginning of the Alpine cold season. The unstable weather conditions, affecting both the monitored surfaces and the signal propagation, demanded an accurate understanding of the atmospheric effect and the development of a specific correction procedure for radar data. The considered devices are a low-cost optical photography station (OPS) and a ground-based synthetic aperture radar (GB-SAR). The OPS is placed frontally to the glacier surface and measures the daily motion components orthogonal to the line of sight (LOS). The processing is performed through spatial cross-correlation between consecutive images, acquired at the same hours to limit shadow effects. The images are orthorectified on a 1 m-resolution digital surface model (DSM) of the glacier and a pixel-to-metric conversion is performed. The GB-SAR acquires data every 16 minutes. The GB-SAR location is decided aiming at maximising the parallel condition to the LOS and the estimated direction of the main flow. The main processing steps include i) a coherence-driven pixel-selection criterion to identify glacier areas, ii) 2D unwrapping algorithm, iii) atmosphere phase screen (APS) filtering with a newly 2D polynomial model, function of the elevation. The radar maps are also georeferenced on the DSM. Finally, from the 3 different components of the glacier surface motion it is possible to reconstruct the actual deformation vector. The results are mapped on the DSM. The proposed method allows to determine the evolution of the 3-dimensional kinematics of the observed surface; it can be applied in general to the

  17. Filter and Filter Bank Design for Image Texture Recognition

    Energy Technology Data Exchange (ETDEWEB)

    Randen, Trygve

    1997-12-31

    The relevance of this thesis to energy and environment lies in its application to remote sensing such as for instance sea floor mapping and seismic pattern recognition. The focus is on the design of two-dimensional filters for feature extraction, segmentation, and classification of digital images with textural content. The features are extracted by filtering with a linear filter and estimating the local energy in the filter response. The thesis gives a review covering broadly most previous approaches to texture feature extraction and continues with proposals of some new techniques. 143 refs., 59 figs., 7 tabs.

  18. Leukodepletion blood filters: filter design and mechanisms of leukocyte removal.

    Science.gov (United States)

    Dzik, S

    1993-04-01

    Modern leukocyte removal filters have been developed after years of refinement in design. Current filters are composite filters in which synthetic microfiber material is prepared as a nonwoven web. The filter material may be surface modified to alter surface tension or charge to improve performance. The housing design promotes effective contact of blood with the filter material and decreases shear forces. The exact mechanisms by which these filters remove leukocytes from blood components are uncertain, but likely represent a combination of both physical and biological processes whose contributions to leukocyte removal are interdependent. Small-pore microfiber webs result in barrier phenomena that permit retention of individual cells and increase the total adsorptive area of the filter. Modifications in surface charge can increase or decrease cell attraction to the fibers. Optimum interfacial surface tensions between blood cells, plasma, and filter fibers not only permit effective blood flow through small fiber pores, but also facilitate cell contact with the material. Barrier retention is a common mechanism for all modern leukocyte-removal filters and applies to all leukocyte subtypes. Because barrier retention does not depend on cell viability, it is operative for cells of any age and will retain any nondeformable cell, including whole nuclei from lymphocytes or monocytes. Barrier retention is supplemented by retention by adhesion. RBCs, lymphocytes, monocytes, granulocytes, and platelets differ in their relative adhesiveness to filter fibers. Different adhesive mechanisms are used in filters designed for RBCs compared with filters designed for platelets. Although lymphocytes, monocytes, and granulocytes can adhere directly to filter fibers, the biological mechanisms underlying cell adhesion may differ for these cell types. These differences may depend on expression of cell adhesion molecules. In the case of filtration of fresh RBCs, platelet-leukocyte interaction

  19. Tandem HEPA filter tests.

    Science.gov (United States)

    Schuster, B G; Osetek, D J

    1978-02-01

    Current methods for evaluating the performance and reliability of high-efficiency air cleaning systems use forward light-scattering photometers and DOP aerosol. This method is limited to measuring protection factors of 10(4) or 10(5) and has poor sensitivity to particles less than .3 micron. More accurate determination of system performance could be made by measuring two filter stages with a single test. Because of the large protection factors of a two-stage system, it is necessary to use high challenge aerosol concentrations and long downstream sampling times. Concentrations were measured using an intra-cavity laser light-scattering aerosol spectrometer which is capable of detection of single particles ranging in size from 0.07 to 3.00 micron diameter. The results of several tests with challenge aerosols of both NaCl and DOP yielded protection factors ranging from 1.4 x 10(7) to 3.0 x 10(9) for two HEPA filters in series.

  20. Reverse Genetics of SARS-Related Coronavirus Using Vaccinia Virus-Based Recombination

    Science.gov (United States)

    Zevenhoven, Jessika C.; Weber, Friedemann; Züst, Roland; Kuri, Thomas; Dijkman, Ronald; Chang, Guohui; Siddell, Stuart G.; Snijder, Eric J.; Thiel, Volker; Davidson, Andrew D.

    2012-01-01

    Severe acute respiratory syndrome (SARS) is a zoonotic disease caused by SARS-related coronavirus (SARS-CoV) that emerged in 2002 to become a global health concern. Although the original outbreak was controlled by classical public health measures, there is a real risk that another SARS-CoV could re-emerge from its natural reservoir, either in its original form or as a more virulent or pathogenic strain; in which case, the virus would be difficult to control in the absence of any effective antiviral drugs or vaccines. Using the well-studied SARS-CoV isolate HKU-39849, we developed a vaccinia virus-based SARS-CoV reverse genetic system that is both robust and biosafe. The SARS-CoV genome was cloned in separate vaccinia virus vectors, (vSARS-CoV-5prime and vSARS-CoV-3prime) as two cDNAs that were subsequently ligated to create a genome-length SARS-CoV cDNA template for in vitro transcription of SARS-CoV infectious RNA transcripts. Transfection of the RNA transcripts into permissive cells led to the recovery of infectious virus (recSARS-CoV). Characterization of the plaques produced by recSARS-CoV showed that they were similar in size to the parental SARS-CoV isolate HKU-39849 but smaller than the SARS-CoV isolate Frankfurt-1. Comparative analysis of replication kinetics showed that the kinetics of recSARS-CoV replication are similar to those of SARS-CoV Frankfurt-1, although the titers of virus released into the culture supernatant are approximately 10-fold less. The reverse genetic system was finally used to generate a recSARS-CoV reporter virus expressing Renilla luciferase in order to facilitate the analysis of SARS-CoV gene expression in human dendritic cells (hDCs). In parallel, a Renilla luciferase gene was also inserted into the genome of human coronavirus 229E (HCoV-229E). Using this approach, we demonstrate that, in contrast to HCoV-229E, SARS-CoV is not able to mediate efficient heterologous gene expression in hDCs. PMID:22412934