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Sample records for ceriodaphnia cornuta sars

  1. Culture of ceriodaphnia cornuta, using chicken manure as fertilizer: conversion of waste product into highly nutritive animal protein

    International Nuclear Information System (INIS)

    Altaf, K.; War, M.U.D.

    2010-01-01

    For finding a cheap and suitable feed for culture of Ceriodaphnia cornuta studies were carried out for 21 days using chicken manure as fertilizer whereupon C. cornuta population ranged between 50 +- 2 and 10,232 +- 202 Ind./L. (individuals/L). The culture peaked on the 17th day producing the maximum density of 10,232 +- 202 Ind./L. Thus chicken manure can be used as a fertilizer for mass culture of cladocerans, specially C. cornuta. (author)

  2. O potencial de Ceriodaphnia cornuta Sars (1885) fa rigaudi comoorganismo-teste em estudos ecotoxicológicos: uma comparação congênere

    OpenAIRE

    Marcela Martins Ribeiro

    2011-01-01

    O objetivo deste trabalho foi testar a sensibilidade em relação a duas substâncias de referência, cloreto de sódio (NaCl) e dodecil sulfato de sódio- DSS - (C12H25SO4Na) e de amostras de água do reservatório da Pampulha, à Ceriodaphnia cornuta para verificar seu potencial como organismo-teste em estudos ecotoxicológicos. Além disso, foram obtidas informações quanto à reprodução e longevidade desta espécie no contexto individual e populacional. Paralelamente foram conduzidos experimentos utili...

  3. Crescimento populacional e análise isotópica de Diaphanosoma spinolosum e Ceriodaphnia cornuta (Crustacea: Cladocera, alimentadas com diferentes frações de seston natural - doi: 10.4025/actascibiolsci.v33i1.7260 Population growth and stable isotope analyses of Diaphanosoma spinolosum and Ceriodaphnia cornuta (Crustacea: Cladocera fed with different seston size fractions - doi: 10.4025/actascibiolsci.v33i1.7260

    Directory of Open Access Journals (Sweden)

    Bruce Forsberg

    2011-02-01

    Full Text Available Para definir o efeito do seston como fonte de alimento para Ceriodaphnia cornuta e Diaphanosoma spinolosum durante a enchente no lago Catalão (Amazônia Central foram desenvolvidos experimentos “in situ”, utilizando a variação natural de δ13C e δ15N como traçadores de alimento. As duas espécies tiveram acesso a três diferentes frações de seston (D. spinolosum e C. cornuta apresentaram enriquecimento nos valores de delta;13C e δ15N, sendo maior na fração In order to define the effect of seston size fraction as a food source for Ceriodaphnia cornuta and Diaphanosoma spinolosumin, situ experiments using natural abundance of delta;13C and δ15N were carried out during the rising water period in Catalão Lake. Both species were fed with three different fractions of seston from the lake (13C and δ15N. Both species grew in all of the food fractions, with the best the performance coming in the D. spinolosum and C. cornuta showed enrichment in delta;13C and δ15N, which was highest in the < 10 µm fraction for both species. These results show that the seston size fractions tested produce different population growth rates and isotopic signatures in cladocerans.

  4. Biosynthesis of silver nanoparticles using a probiotic Bacillus licheniformis Dahb1 and their antibiofilm activity and toxicity effects in Ceriodaphnia cornuta.

    Science.gov (United States)

    Shanthi, Sathappan; Jayaseelan, Barbanas David; Velusamy, Palaniyandi; Vijayakumar, Sekar; Chih, Cheng Ta; Vaseeharan, Baskaralingam

    2016-04-01

    In the present study, we synthesized and characterized a probiotic Bacillus licheniformis cell free extract (BLCFE) coated silver nanoparticles (BLCFE-AgNPs). These BLCFE-AgNPs were characterized by UV-visible spectrophotometer, XRD, EDX, FTIR, TEM and AFM. A strong surface plasmon resonance centered at 422 nm in UV-visible spectrum indicates the formation of AgNPs. The XRD spectrum of silver nanoparticles exhibited 2θ values corresponding to the silver nanocrystal. TEM and AFM showed the AgNPs were spherical in shape within the range of 18.69-63.42 nm and the presence of silver was confirmed by EDX analysis. Light and Confocal Laser Scanning Microscope (CLSM) images showed a weak adherence and disintegrated biofilm formation of Vibrio parahaemolyticus Dav1 treated with BLCFE-AgNPs compared to control. This result suggests that BLCFE-AgNps may be used for the control of biofilm forming bacterial populations in the biomedical field. In addition, acute toxicity results concluded that BLCFE-AgNPs were less toxic to the fresh water crustacean Ceriodaphnia cornuta (50 μg/ml) when compared to AgNO3 (22 μg/ml). This study also reports a short term analysis (24 h) of uptake and depuration of BLCFE-AgNPs in C. cornuta. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Vitamin D status of wild Ricord's iguanas (Cyclura ricordii) and captive and wild rhinoceros iguanas (Cyclura cornuta cornuta) in the Dominican Republic.

    Science.gov (United States)

    Ramer, Jan C; Maria, Roberto; Reichard, Tim; Tolson, Peter J; Chen, Tai C; Holick, Michael F

    2005-06-01

    Calcidiol (25-hydroxyvitamin D) values are reported for 22 wild Ricord's iguanas (Cyclura ricordii) and seven wild rhinoceros iguanas (Cyclura cornuta cornuta). Calcitriol (1,25-hydroxyvitamin D) values are reported for 12 wild Ricord's iguanas and seven wild rhinoceros iguanas. These animals were captured as part of a larger health assessment study being conducted on Ricord's iguanas in Isla Cabritos National Park, Dominican Republic. A total of 13 captive rhinoceros iguanas held outdoors at Parque Zoológico Nacional were also sampled for comparison. Mean concentrations of 25-hydroxyvitamin D were 554 nmol/L (222 ng/ml) with a range of 250-1,118 nmol/L (100-448 ng/ml) for wild Ricord's iguanas, 332 nmol/L (133 ng/ml) with a range of 260-369 nmol/L (104-148 ng/ml) for wild rhinoceros iguanas, and 317 nmol/L (127 ng/ml) with a range of 220-519 nmol/L (88-208 ng/ml) for captive rhinoceros iguanas. On the basis of these results, serum concentrations of at least 325 nmol/L (130 ng/ml) for 25-hydroxyvitamin D should be considered normal for healthy Ricord's and rhinoceros iguanas.

  6. Tiny but complex - interactive 3D visualization of the interstitial acochlidian gastropod Pseudunela cornuta (Challis, 1970

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    Heß Martin

    2009-09-01

    Full Text Available Abstract Background Mesopsammic acochlidians are small, and organ complexity may be strongly reduced (regressive evolution by progenesis, especially in microhedylacean species. The marine interstitial hedylopsacean Pseudunela cornuta (Challis, 1970, however, was suggested as having a complex reproductive system resembling that of much larger, limnic and benthic species. The present study aims to reconstruct the detailed anatomy and true complexity of P. cornuta from serial, semithin histological sections by using modern computer-based 3D visualization with Amira software, and to explain it in an evolutionary context. Results Our results demonstrate considerable discordance with the original species description, which was based solely on paraffin sections. Here, we show that the nervous system of P. cornuta has paired rhinophoral, optic and gastro-oesophageal ganglia, three distinct ganglia on the visceral nerve cord, and a putative osphradial ganglion, while anterior accessory ganglia are absent. The presence of an anal genital cloaca is clearly rejected and the anus, nephropore and gonopore open separately to the exterior; the circulatory and excretory systems are well-differentiated, including a two-chambered heart and a complex kidney with a long, looped nephroduct; the special androdiaulic reproductive system shows two allosperm receptacles, three nidamental glands, a cavity with unknown function, as well as highly complex anterior copulatory organs with two separate glandular and impregnatory systems including a penial stylet that measures approximately a third of the whole length of the preserved specimen. Conclusion In spite of its small body size, the interstitial hermaphroditic P. cornuta shows high complexity regarding all major organ systems; the excretory system is as differentiated as in species of the sister clade, the limnic and much larger Acochlidiidae, and the reproductive system is by far the most elaborated one ever observed

  7. Ceriodaphnia and Chironomus in situ toxicity tests assessing the wastewater treatment efficacy of constructed wetlands

    International Nuclear Information System (INIS)

    Barjaktarovic, L.; Nix, P.; Gulley, J.

    1995-01-01

    In situ toxicity tests were designed for Ceriodaphnia dubia and Chironomus tentans as part of a larger study designed to assess the effectiveness of constructed wetlands for the treatment of wastewater produced by oil production at Suncor OSG. The artificial wetlands were 50m long by 3m wide, with three replicates of the control and the treatment. Each wetland had four sample sites equidistant along its length, creating a gradient of treatment from site A being the most toxic to site D being the least toxic. Each test was conducted twice during the summer of 1994. Both the Ceriodaphnia and Chironomus test cages were a flow through design to allow for maximal exposure to the water within the wetlands. Mortality and reproduction were used as endpoints for Ceriodaphnia, whereas mortality and growth were used as endpoints for the Chironomus test. Test durations were fifteen and ten days respectively. Chironomus had very high mortality along the entire wetlands whereas Ceriodaphnia survival and fecundity increased along the length of the treatment wetlands. Both organisms had low mortality and high growth/fecundity in the control wetlands

  8. Indicators of Ceriodaphnia dubia chronic toxicity test performance and sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Rosebrock, M.M.; Bedwell, N.J.; Ausley, L.W. [North Carolina Division of Environmental Management, Raleigh, NC (United States)

    1994-12-31

    The North Carolina Division of Environmental Management has begun evaluation of the sensitivity of test results used for measuring chronic whole effluent toxicity in North Carolina wastewater discharges. Approximately 67% of 565 facilities required to monitor toxicity by an NPDES permit perform a Ceriodaphnia dubia chronic, single effluent concentration (pass/fail) analysis. Data from valid Ceriodaphnia dubia chronic pass/fail tests performed by approximately 20 certified biological laboratories and submitted by North Carolina NPDES permittees were recorded beginning January 1992. Control and treatment reproduction data from over 2,500 tests submitted since 1992 were analyzed to determine the minimum significant difference (MSD) at a 99% confidence level for each test and the percent reduction from the control mean that the MSD represents (%MSD) for each certified laboratory. Initial results for the 20 laboratories indicate that the average intralaboratory percent MSD ranges 12.72% (n = 367) to 34.91% (n = 7) with an average of 23.08%. Additionally, over 3,800 tests were analyzed to determine the coefficient of variation (CV) for control reproduction for each test and the average for each certified biological laboratory. Preliminary review indicates that average interlaboratory control reproduction CV values range from 10.59% (n = 367) to 31.08% (n = 572) with a mean of 20.35%. The statistics investigated are indicators of intra/interlaboratory performance and sensitivity of Ceriodaphnia chronic toxicity analyses.

  9. Further occurrences of Dohrniphora cornuta (Bigot) (Diptera, Phoridae) in forensic cases indicate likely importance of this species in future cases.

    Science.gov (United States)

    Disney, R Henry L; Garcia-Rojo, Ana; Lindström, Anders; Manlove, John D

    2014-08-01

    Dohrniphora cornuta (Bigot), an oriental species of scuttle fly, has been transported around the world by man. We report it from forensic cases in England, Spain and Sweden. It is likely to feature in forensic cases elsewhere in the world. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  10. Reproductive success and mortality rates of Ceriodaphnia dubia maintained in water from Upper Three Runs, Pen Branch, and Fourmile Branch

    International Nuclear Information System (INIS)

    Specht, W.L.

    1994-12-01

    It is anticipated that the new SRS NPDES permit will require toxicity testing of at numerous outfalls and receiving streams, using the standard test species, Ceriodaphnia dubia. Because SRS surface waters differ markedly from the standard culture water that is used for Ceriodaphnia, studies were undertaken to determine if unimpacted SRS surface waters will support this species. Three SRS surface waters were evaluated; Upper Three Runs at Road 8-1, Pen Branch at Road B, and Fourmile Branch at Road F. Toxicity tests were performed monthly on each water source for eleven months. All three water sources exhibited varying degrees of toxicity to Ceriodaphnia, with Pen Branch being the least toxic and Fourmile Branch being the most toxic. These results indicate that if in-stream toxicity testing is required, it may not be possible to separate the naturally occurring toxic effects of the receiving water from possible toxic effects of SRS effluents

  11. The Acute Toxicity of Major Ion Salts to Ceriodaphnia dubia. III. Mathematical models for mixture toxicity

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset concerns the development of models for describing the acute toxicity of major ions to Ceriodaphnia dubia using data from single salt tests and binary...

  12. on the Population Growth of the Cladoceran Ceriodaphnia quadrangula (O. F. Muller, 1785.

    Directory of Open Access Journals (Sweden)

    Sevgi Savaş

    2015-12-01

    Full Text Available Cladoceran Ceriodaphnia quadrangula (O.F. Muller, 1785’nın populasyon artışı üzerine sıcaklık ve besin (Scenedesmus acuminatus (von Lagerheim R. H. Chodat yoğunluğunun etkisi. Bu çalışmada, Ceriodaphnia quadrangula’nın populasyon artışı üzerine sıcaklık (20, 25 ve 30 ºC ve farklı besin (Scenedesmus acuminatus yoğunluğunun (15,30,45, 60 ve75x104 h/ml etkisi incelenmiştir. Deneme 16 aydınlık:8 saat karanlık ışık uygulamasında gerçekleştirilmiştir. Deneme başında, farklı besin yoğunlukları içeren her bir tüpe 1 adet 24 saatten genç birey konulmuş, birey sayısı ve büyüme hızı 25 gün süre ile belirlenmiştir. En yüksek birey sayısı (21,433±0,750 birey/ml ve büyüme hızı (0,240±0,004 25 ºC’de 45x104 h/ml’de belirlenmiştir. Besin yoğunluğunun artması, Ceriodaphnia quadrangula’nın birey sayısı ve büyüme hızını arttırmıştır. Farklı besin yoğunluklarının birey sayısına etkisi istatistiki olarak önemli (P0,05 olduğu bulunmuştur

  13. EFFECTIVE CONCENTRATIONS OF 6 CONTAMINANTS TO LEMMA MINOR, PIMEPHALES PROMELA, DAPHNIA MAGNA, AND CERIODAPHNIA DUBIA

    Science.gov (United States)

    The research presented here resulted in EC50 and LOEC values for the contaminants copper, cadmium, diazinon, atrazine, and cyanide to the species Lemna Minor, Pimephales promelas, Daphnia magna, and Ceriodaphnia dubia. Observed values were used as benchmarks for assessing the se...

  14. Interaction of chemical cues from fish tissues and organophosphorous pesticides on Ceriodaphnia dubia survival

    International Nuclear Information System (INIS)

    Maul, Jonathan D.; Farris, Jerry L.; Lydy, Michael J.

    2006-01-01

    Cladocera are frequently used as test organisms for assessing chemical and effluent toxicity and have been shown to respond to stimuli and cues from potential predators. In this study, the interactive effects of visual and chemical cues of fish and two organophosphorous pesticides on survival of Ceriodaphnia dubia were examined. A significant chemical cue (homogenized Pimephales promelas) and malathion interaction was observed on C. dubia survival (P = 0.006). Chemical cue and 2.82 μg/L malathion resulted in a 76.0% reduction in survival compared to malathion alone (P < 0.01). Furthermore, potentiation of malathion toxicity varied based on the source of chemical cues (i.e., epithelial or whole body). It is unclear in this study whether these chemical cues elicited a predation-related stress in C. dubia. Future research should examine the mechanism of this interaction and determine what role, if any, stress responses by C. dubia might play in the interaction. - Potentiation of organophosphorous pesticide toxicity to Ceriodaphnia dubia by fathead minnow (Pimephales promelas) chemical cues was observed

  15. Ceriodaphnia dubia as a potential bio-indicator for assessing acute aluminum oxide nanoparticle toxicity in fresh water environment.

    Directory of Open Access Journals (Sweden)

    Sunandan Pakrashi

    Full Text Available Growing nanomaterials based consumer applications have raised concerns about their potential release into the aquatic ecosystems and the consequent toxicological impacts. So environmental monitoring of the nanomaterials in aqueous systems becomes imperative. The current study reveals the potential of Ceriodaphnia dubia (C. dubia as a bio-indicator for aluminum oxide nanoparticles in a fresh water aquatic ecosystem where it occupies an important ecological niche as a primary consumer. This study aims to investigate the aluminium oxide nanoparticle induced acute toxicity on Ceriodaphnia dubia in a freshwater system. The bioavailability of the aluminum oxide nanoparticles has been studied with respect to their aggregation behavior in the system and correlated with the toxicity endpoints. The oxidative stress generated by the particles contributed greatly toward their toxicity. The crucial role of leached aluminium ion mediated toxicity in the later phases (48 h and 72 h in conjunction with the effects from the nano-sized particles in the initial phases (24 h puts forth the dynamics of nanotoxicity in the test system. The internalization of nanoparticles (both gross and systemic uptake as substantiated through the transmission electron microscopy (TEM and inductively coupled plasma optical emission spectral (ICP-OES analysis was another major contributor toward acute toxicity. Concluding the present study, Ceriodaphnia dubia can be a promising candidate for bio-monitoring the aluminium oxide nanoparticles in a fresh water system.

  16. The neonicotinoid clothianidin interferes with navigation of the solitary bee Osmia cornuta in a laboratory test.

    Science.gov (United States)

    Jin, Nanxiang; Klein, Simon; Leimig, Fabian; Bischoff, Gabriela; Menzel, Randolf

    2015-09-01

    Pollinating insects provide a vital ecosystem service to crops and wild plants. Exposure to low doses of neonicotinoid insecticides has sub-lethal effects on social pollinators such as bumblebees and honeybees, disturbing their navigation and interfering with their development. Solitary Hymenoptera are also very important ecosystem service providers, but the sub-lethal effects of neonicotinoids have not yet been studied well in those animals. We analyzed the ability of walking Osmia to remember a feeding place in a small environment and found that Osmia remembers the feeding place well after 4 days of training. Uptake of field-realistic amounts of the neonicotinoid clothianidin (0.76 ng per bee) altered the animals' sensory responses to the visual environment and interfered with the retrieval of navigational memory. We conclude that the neonicotinoid clothianidin compromises visual guidance and the use of navigational memory in the solitary bee Osmia cornuta. © 2015. Published by The Company of Biologists Ltd.

  17. Longevity and reproduction of Ceriodaphnia dubia in receiving waters

    International Nuclear Information System (INIS)

    Stewart, A.J.; Konetsky, B.K.

    1998-01-01

    Seven-day tests with Ceriodaphnia dubia are commonly used to estimate toxicity of effluents or receiving waters but can sometimes yield no toxicity outcomes even if pollutants are present. The authors conducted two sets of full life-cycle tests with C. dubia to (1) determine whether tests with longer exposure periods to low concentrations of contaminants in ambient water might reveal evidence of toxicity that could not be discerned from 7-d tests and (2) determine the relative importance of water quality versus food as factors influencing C. dubia longevity and reproduction. In the first set of tests, C. dubia was reared in diluted mineral water (a negative control), water from a stream impacted by coal fly-ash, or water from a retention basin containing sediments contaminated with mercury, other metals, and polychlorinated biphenyls. The second set of tests used water from the retention basin only. Before testing, though, water in the second set of tests was either filtered or not filtered, and food was either added or not added. Ceriodaphnia dubia longevity and reproduction did not differ much among the three water types in the first set of tests, but both longevity and reproduction were strongly affected by the filtering and food-addition treatments in the second set of tests. Thus, C. dubia appeared to be relatively insensitive to general water quality factors but sensitive to food-related factors. In five of the six full life-cycle tests, lifetime reproduction by C. dubia could not be reliably predicted from reproduction data from the first 7 d of testing. The increase in predictability of lifetime reproduction of C. dubia as a function of test duration also differed among water types in the first set of tests and among treatments in the second set of tests. This, it may not be possible to reliably extrapolate the results of 7-d tests with C. dubia to longer time scales

  18. Combined DEM Extration Method from StereoSAR and InSAR

    Science.gov (United States)

    Zhao, Z.; Zhang, J. X.; Duan, M. Y.; Huang, G. M.; Yang, S. C.

    2015-06-01

    A pair of SAR images acquired from different positions can be used to generate digital elevation model (DEM). Two techniques exploiting this characteristic have been introduced: stereo SAR and interferometric SAR. They permit to recover the third dimension (topography) and, at the same time, to identify the absolute position (geolocation) of pixels included in the imaged area, thus allowing the generation of DEMs. In this paper, StereoSAR and InSAR combined adjustment model are constructed, and unify DEM extraction from InSAR and StereoSAR into the same coordinate system, and then improve three dimensional positioning accuracy of the target. We assume that there are four images 1, 2, 3 and 4. One pair of SAR images 1,2 meet the required conditions for InSAR technology, while the other pair of SAR images 3,4 can form stereo image pairs. The phase model is based on InSAR rigorous imaging geometric model. The master image 1 and the slave image 2 will be used in InSAR processing, but the slave image 2 is only used in the course of establishment, and the pixels of the slave image 2 are relevant to the corresponding pixels of the master image 1 through image coregistration coefficient, and it calculates the corresponding phase. It doesn't require the slave image in the construction of the phase model. In Range-Doppler (RD) model, the range equation and Doppler equation are a function of target geolocation, while in the phase equation, the phase is also a function of target geolocation. We exploit combined adjustment model to deviation of target geolocation, thus the problem of target solution is changed to solve three unkonwns through seven equations. The model was tested for DEM extraction under spaceborne InSAR and StereoSAR data and compared with InSAR and StereoSAR methods respectively. The results showed that the model delivered a better performance on experimental imagery and can be used for DEM extraction applications.

  19. Effect of organic media on growth and development of patiola F1 horned violet (Viola cornuta L.

    Directory of Open Access Journals (Sweden)

    Dorota Janicka

    2013-04-01

    Full Text Available The specificity of horticultural production makes it possible to use substrates based on compost from municipal and industrial waste, particularly in the cultivation of ornamental plants. Experiments were conducted in the years 2005–2007. Six horned violet cultivars (Viola cornuta  L. from Patiola F1 group and four substrates were used in them: I – sphagnum peat; II – substrate from peat and compost 1 (1:1 v/v; III – substrate from peat and compost 2 (1:1 v/v; IV – coconut fibre. Compost 1 was prepared using municipal sewage sludge (35%, potato pulp (35% and straw (30%. Compost 2 was prepared using municipal sewage sludge (35%, potato pulp (35% and sawdust (30%. Composts after 10 months of composting were used in the research. The addition of municipal sewage sludge composts did not cause observable adverse changes in plants grown. Composts made from municipal sewage sludge are rich in nutrients. Plants that are grown in substrates with the addition of composts and in a peat substrate grow and develop properly without the necessity of introducing top dressing.

  20. Effects of depleted uranium on the health and survival of Ceriodaphnia dubia and Hyalella azteca

    Science.gov (United States)

    Kuhne, W.W.; Caldwell, C.A.; Gould, W.R.; Fresquez, P.R.; Finger, S.

    2002-01-01

    Depleted uranium (DU) has been used as a substitute for the fissionable enriched uranium component of atomic weapons tested at Los Alamos National Laboratory (LANL) (Los Alamos, NM, USA) since the early 1950s, resulting in considerable concentrations of DU in the soils within the test sites. Although the movement of DU into major aquatic systems has been shown to be minimal, there are many small-order ephemeral streams and areas of standing water in canyons throughout LANL that may be affected by inputs of DU via runoff, erosion, and leaching. Ninety-six-hour acute and 7-d chronic toxicity assays were conducted to measure the toxicity of DU on survival and reproduction of Ceriodaphnia dubia. A 14-d water-only assay was conducted to measure survival and growth of Hyalella azteca. The estimated median lethal concentration (LC50) to produce 50% mortality of the test population for the 96-h Ceriodaphnia dubia assay was 10.50 mg/L. Reproductive effects occurred at a lowest-observable-effect concentration ???3.91 mg/L with a no-observable-effect concentration of 1.97 mg/L. The estimated 14-d LC50 for the Hyalella azteca assay was 1.52 mg/L No significant relationship was detected between growth and DU concentrations. Concentrations at which toxicity effects were observed in this study for both invertebrates exceeded concentrations of total uranium observed in runoff from LANL lands. Thus, it is likely that current runoff levels of uranium do not pose a threat to these types of aquatic invertebrates.

  1. Individual and binary toxicity of anatase and rutile nanoparticles towards Ceriodaphnia dubia

    International Nuclear Information System (INIS)

    Iswarya, V.; Bhuvaneshwari, M.; Chandrasekaran, N.; Mukherjee, Amitava

    2016-01-01

    Highlights: • Individual, binary toxicity of anatase and rutile NPs studied on Ceriodaphnia dubia. • Anatase and rutile phases showed differential effect upon variation in irradiation. • Mixture induced antagonistic at visible and additive effect at UV-A irradiation. • Marking-Dawson model fitted more appropriately than Abbott model. • Agglomeration played a major role in the toxicity induced by the mixture. - Abstract: Increasing usage of engineered nanoparticles, especially Titanium dioxide (TiO_2) in various commercial products has necessitated their toxicity evaluation and risk assessment, especially in the aquatic ecosystem. In the present study, a comprehensive toxicity assessment of anatase and rutile NPs (individual as well as a binary mixture) has been carried out in a freshwater matrix on Ceriodaphnia dubia under different irradiation conditions viz., visible and UV-A. Anatase and rutile NPs produced an LC_5_0 of about 37.04 and 48 mg/L, respectively, under visible irradiation. However, lesser LC_5_0 values of about 22.56 (anatase) and 23.76 (rutile) mg/L were noted under UV-A irradiation. A toxic unit (TU) approach was followed to determine the concentrations of binary mixtures of anatase and rutile. The binary mixture resulted in an antagonistic and additive effect under visible and UV-A irradiation, respectively. Among the two different modeling approaches used in the study, Marking-Dawson model was noted to be a more appropriate model than Abbott model for the toxicity evaluation of binary mixtures. The agglomeration of NPs played a significant role in the induction of antagonistic and additive effects by the mixture based on the irradiation applied. TEM and zeta potential analysis confirmed the surface interactions between anatase and rutile NPs in the mixture. Maximum uptake was noticed at 0.25 total TU of the binary mixture under visible irradiation and 1 TU of anatase NPs for UV-A irradiation. Individual NPs showed highest uptake under

  2. Individual and binary toxicity of anatase and rutile nanoparticles towards Ceriodaphnia dubia

    Energy Technology Data Exchange (ETDEWEB)

    Iswarya, V.; Bhuvaneshwari, M.; Chandrasekaran, N.; Mukherjee, Amitava, E-mail: amit.mookerjea@gmail.com

    2016-09-15

    Highlights: • Individual, binary toxicity of anatase and rutile NPs studied on Ceriodaphnia dubia. • Anatase and rutile phases showed differential effect upon variation in irradiation. • Mixture induced antagonistic at visible and additive effect at UV-A irradiation. • Marking-Dawson model fitted more appropriately than Abbott model. • Agglomeration played a major role in the toxicity induced by the mixture. - Abstract: Increasing usage of engineered nanoparticles, especially Titanium dioxide (TiO{sub 2}) in various commercial products has necessitated their toxicity evaluation and risk assessment, especially in the aquatic ecosystem. In the present study, a comprehensive toxicity assessment of anatase and rutile NPs (individual as well as a binary mixture) has been carried out in a freshwater matrix on Ceriodaphnia dubia under different irradiation conditions viz., visible and UV-A. Anatase and rutile NPs produced an LC{sub 50} of about 37.04 and 48 mg/L, respectively, under visible irradiation. However, lesser LC{sub 50} values of about 22.56 (anatase) and 23.76 (rutile) mg/L were noted under UV-A irradiation. A toxic unit (TU) approach was followed to determine the concentrations of binary mixtures of anatase and rutile. The binary mixture resulted in an antagonistic and additive effect under visible and UV-A irradiation, respectively. Among the two different modeling approaches used in the study, Marking-Dawson model was noted to be a more appropriate model than Abbott model for the toxicity evaluation of binary mixtures. The agglomeration of NPs played a significant role in the induction of antagonistic and additive effects by the mixture based on the irradiation applied. TEM and zeta potential analysis confirmed the surface interactions between anatase and rutile NPs in the mixture. Maximum uptake was noticed at 0.25 total TU of the binary mixture under visible irradiation and 1 TU of anatase NPs for UV-A irradiation. Individual NPs showed highest

  3. Composición taxonómica del zooplancton del embalse de Betania, departamento del Huila, Colombia

    Directory of Open Access Journals (Sweden)

    Yimy Herrera Martinez

    1999-01-01

    Full Text Available To determine the species composition of the zooplancton in the reservoir Betania (altitude; 560 m.a.s.l.; area: 7.4 km2; vol: 1971 x 106 m3; mean depht 28 m, at seven sites and several depths, bimonthly net samples (100 and 200 microns mesh size were taken during 1991.  Alltogether 24 species were found: Thermocyclops decipiens (Crustacea, Copepoda, Moina sp., Ceriodaphnia cornuta y Allona sp. (Crustacea, Cladocera; 19 species of rotífers, of which 7 belong to the genus Brachionus, as well as larvas of the dipter Chaoborus sp. For the first time Brachionus havanaensis, B. falcatus falcatus, b. quadridentatus, y Platyias cuadricornis  f. brevispinus  were found in Colombia.  The species composition was compared with the composition of other lakes and comparison shows that the Betania reservoir has a typical species composition for warms tropical lakes.

  4. TerraSAR-X InSAR multipass analysis on Venice, Italy)

    Science.gov (United States)

    Nitti, D. O.; Nutricato, R.; Bovenga, F.; Refice, A.; Chiaradia, M. T.; Guerriero, L.

    2009-09-01

    The TerraSAR-X (copyright) mission, launched in 2007, carries a new X-band Synthetic Aperture Radar (SAR) sensor optimally suited for SAR interferometry (InSAR), thus allowing very promising application of InSAR techniques for the risk assessment on areas with hydrogeological instability and especially for multi-temporal analysis, such as Persistent Scatterer Interferometry (PSI) techniques, originally developed at Politecnico di Milano. The SPINUA (Stable Point INterferometry over Unurbanised Areas) technique is a PSI processing methodology which has originally been developed with the aim of detection and monitoring of coherent PS targets in non or scarcely-urbanized areas. The main goal of the present work is to describe successful applications of the SPINUA PSI technique in processing X-band data. Venice has been selected as test site since it is in favorable settings for PSI investigations (urban area containing many potential coherent targets such as buildings) and in view of the availability of a long temporal series of TerraSAR-X stripmap acquisitions (27 scenes in all). The Venice Lagoon is affected by land sinking phenomena, whose origins are both natural and man-induced. The subsidence of Venice has been intensively studied for decades by determining land displacements through traditional monitoring techniques (leveling and GPS) and, recently, by processing stacks of ERS/ENVISAT SAR data. The present work is focused on an independent assessment of application of PSI techniques to TerraSAR-X stripmap data for monitoring the stability of the Venice area. Thanks to its orbital repeat cycle of only 11 days, less than a third of ERS/ENVISAT C-band missions, the maximum displacement rate that can be unambiguously detected along the Line-of-Sight (LOS) with TerraSAR-X SAR data through PSI techniques is expected to be about twice the corresponding value of ESA C-band missions, being directly proportional to the sensor wavelength and inversely proportional to the

  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 - Diagnosis

    Indian Academy of Sciences (India)

    SARS - Diagnosis. Mainly by exclusion of known causes of atypical pneumonia; * X ray Chest; * PCR on body fluids- primers defined by WHO centres available from website.-ve result does not exclude SARS. * Sequencing of amplicons; * Viral Cultures – demanding; * Antibody tests.

  7. 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

  8. Keynote presentation : SAR systems

    NARCIS (Netherlands)

    Halsema, D. van; Otten, M.P.G.; Maas, A.P.M.; Bolt, R.J.; Anitori, L.

    2011-01-01

    Synthetic Aperture Radar (SAR) systems are becoming increasingly important sensors in as well the military environment as in the civilian market. In this keynote presentation an overview will be given over more than 2 decades of SAR system∼ and SAR application development at TNO in the Netherlands.

  9. 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.

  10. The Seamless SAR Archive (SSARA) Project and Other SAR Activities at UNAVCO

    Science.gov (United States)

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

    2014-12-01

    The seamless synthetic aperture radar archive (SSARA) implements a seamless distributed access system for SAR data and derived data products (i.e. interferograms). SSARA provides a unified application programming interface (API) for SAR data search and results at the Alaska Satellite Facility 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. Interest from the international community has prompted an effort to incorporate ESA's Virtual Archive 4 Geohazard Supersites and Natural Laboratories (GSNL) collections and other archives into the federated query service. SSARA also provides Digital Elevation Model access for topographic correction via a simple web service through OpenTopography and tropospheric correction products through JPL's OSCAR service. Additionally, UNAVCO provides data storage capabilities for WInSAR PIs with approved TerraSAR-X and ALOS-2 proposals which allows easier distribution to US collaborators on associated proposals and facilitates data access through the SSARA web services. Further work is underway to incorporate federated data discovery for GSNL across SAR, GPS, and seismic datasets provided by web services from SSARA, GSAC, and COOPEUS.

  11. 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.

  12. 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). ...

  13. SAR Target Recognition via Supervised Discriminative Dictionary Learning and Sparse Representation of the SAR-HOG Feature

    Directory of Open Access Journals (Sweden)

    Shengli Song

    2016-08-01

    Full Text Available Automatic target recognition (ATR in synthetic aperture radar (SAR images plays an important role in both national defense and civil applications. Although many methods have been proposed, SAR ATR is still very challenging due to the complex application environment. Feature extraction and classification are key points in SAR ATR. In this paper, we first design a novel feature, which is a histogram of oriented gradients (HOG-like feature for SAR ATR (called SAR-HOG. Then, we propose a supervised discriminative dictionary learning (SDDL method to learn a discriminative dictionary for SAR ATR and propose a strategy to simplify the optimization problem. Finally, we propose a SAR ATR classifier based on SDDL and sparse representation (called SDDLSR, in which both the reconstruction error and the classification error are considered. Extensive experiments are performed on the MSTAR database under standard operating conditions and extended operating conditions. The experimental results show that SAR-HOG can reliably capture the structures of targets in SAR images, and SDDL can further capture subtle differences among the different classes. By virtue of the SAR-HOG feature and SDDLSR, the proposed method achieves the state-of-the-art performance on MSTAR database. Especially for the extended operating conditions (EOC scenario “Training 17 ∘ —Testing 45 ∘ ”, the proposed method improves remarkably with respect to the previous works.

  14. Simultaneous Observation Data of GB-SAR/PiSAR to Detect Flooding in an Urban Area

    Directory of Open Access Journals (Sweden)

    Manabu Watanabe

    2010-01-01

    Full Text Available We analyzed simultaneous observation data with ground-based synthetic aperture radar (GB-SAR and airborne SAR (PiSAR over a flood test site at which a simple house was constructed in a field. The PiSAR σ∘ under flood condition was 0.9 to 3.4 dB higher than that under nonflood condition. GB-SAR gives high spatial resolution as we could identify a single scattering component and a double bounce component from the house. GB-SAR showed that the σ∘ difference between the flooding and nonflooding conditions came from the double bounce scattering. We also confirm that the entropy is a sensitive parameter in the eigenvalue decomposition parameters, if the scattering process is dominated by the double bounce scattering. We conclude that σ∘ and entropy are a good parameter to be used to detect flooding, not only in agricultural and forest regions, but also in urban areas. We also conclude that GB-SAR is a powerful tool to supplement satellite and airborne observation, which has a relatively low spatial resolution.

  15. Simultaneous Observation Data of GB-SAR/PiSAR to Detect Flooding in an Urban Area

    Directory of Open Access Journals (Sweden)

    Shimada Masanobu

    2010-01-01

    Full Text Available Abstract We analyzed simultaneous observation data with ground-based synthetic aperture radar (GB-SAR and airborne SAR (PiSAR over a flood test site at which a simple house was constructed in a field. The PiSAR under flood condition was 0.9 to 3.4 dB higher than that under nonflood condition. GB-SAR gives high spatial resolution as we could identify a single scattering component and a double bounce component from the house. GB-SAR showed that the difference between the flooding and nonflooding conditions came from the double bounce scattering. We also confirm that the entropy is a sensitive parameter in the eigenvalue decomposition parameters, if the scattering process is dominated by the double bounce scattering. We conclude that and entropy are a good parameter to be used to detect flooding, not only in agricultural and forest regions, but also in urban areas. We also conclude that GB-SAR is a powerful tool to supplement satellite and airborne observation, which has a relatively low spatial resolution.

  16. 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.

  17. 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.

  18. Therapeutic effects of gold nanoparticles synthesized using Musa paradisiaca peel extract against multiple antibiotic resistant Enterococcus faecalis biofilms and human lung cancer cells (A549).

    Science.gov (United States)

    Vijayakumar, S; Vaseeharan, B; Malaikozhundan, B; Gopi, N; Ekambaram, P; Pachaiappan, R; Velusamy, P; Murugan, K; Benelli, G; Suresh Kumar, R; Suriyanarayanamoorthy, M

    2017-01-01

    Botanical-mediated synthesis of nanomaterials is currently emerging as a cheap and eco-friendly nanotechnology, since it does not involve the use of toxic chemicals. In the present study, we focused on the synthesis of gold nanoparticles using the aqueous peel extract of Musa paradisiaca (MPPE-AuNPs) following a facile and cheap fabrication process. The green synthesized MPPE-AuNPs were bio-physically characterized by UV-Vis spectroscopy, FTIR, XRD, TEM, Zeta potential analysis and EDX. MPPE-AuNPs were crystalline in nature, spherical to triangular in shape, with particle size ranging within 50 nm. The biofilm inhibition activity of MPPE-AuNPs was higher against multiple antibiotic resistant (MARS) Gram-positive Enterococcus faecalis. Light and confocal laser scanning microscopic observations evidenced that the MPPE-AuNPs effectively inhibited the biofilm of E. faecalis when tested at 100 μg mL -1 . Cytotoxicity studies demonstrated that MPPE-AuNPs were effective in inhibiting the viability of human A549 lung cancer cells at higher concentrations of 100 μg mL -1 . The morphological changes in the MPPE-AuNPs treated A549 lung cancer cells were visualized under phase-contrast microscopy. Furthermore, the ecotoxicity of MPPE-AuNPs on the freshwater micro crustacean Ceriodaphnia cornuta were evaluated. Notably, no mortality was recorded in MPPE-AuNPs treated C. cornuta at 250 μg mL -1 . This study concludes that MPPE-AuNPs are non-toxic, eco-friendly and act as a multipurpose potential biomaterial for biomedical applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. 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...

  20. 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

  1. Design and realization of an active SAR calibrator for TerraSAR-X

    Science.gov (United States)

    Dummer, Georg; Lenz, Rainer; Lutz, Benjamin; Kühl, Markus; Müller-Glaser, Klaus D.; Wiesbeck, Werner

    2005-10-01

    TerraSAR-X is a new earth observing satellite which will be launched in spring 2006. It carries a high resolution X-band SAR sensor. For high image data quality, accurate ground calibration targets are necessary. This paper describes a novel system concept for an active and highly integrated, digitally controlled SAR system calibrator. A total of 16 active transponder and receiver systems and 17 receiver only systems will be fabricated for a calibration campaign. The calibration units serve for absolute radiometric calibration of the SAR image data. Additionally, they are equipped with an extra receiver path for two dimensional satellite antenna pattern recognition. The calibrator is controlled by a dedicated digital Electronic Control Unit (ECU). The different voltages needed by the calibrator and the ECU are provided by the third main unit called Power Management Unit (PMU).

  2. 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.

  3. Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Diego O Andrey

    Full Text Available Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1, encoded by tst(H, and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1, RNAIII, rot, and the alternative stress sigma factor sigB (σB. By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression.

  4. Effects of water quality parameters on boron toxicity to Ceriodaphnia dubia.

    Science.gov (United States)

    Dethloff, Gail M; Stubblefield, William A; Schlekat, Christian E

    2009-07-01

    The potential modifying effects of certain water quality parameters (e.g., hardness, alkalinity, pH) on the acute toxicity of boron were tested using a freshwater cladoceran, Ceriodaphnia dubia. By comparison, boron acute toxicity was less affected by water quality characteristics than some metals (e.g., copper and silver). Increases in alkalinity over the range tested did not alter toxicity. Increases in water hardness appeared to have an effect with very hard waters (>500 mg/L as CaCO(3)). Decreased pH had a limited influence on boron acute toxicity in laboratory waters. Increasing chloride concentration did not provide a protective effect. Boron acute toxicity was unaffected by sodium concentrations. Median acute lethal concentrations (LC(50)) in natural water samples collected from three field sites were all greater than in reconstituted laboratory waters that matched natural waters in all respects except for dissolved organic carbon. Water effect ratios in these waters ranged from 1.4 to 1.8. In subsequent studies using a commercially available source of natural organic matter, acute toxicity decreased with increased dissolved organic carbon, suggesting, along with the natural water studies, that dissolved organic carbon should be considered further as a modifier of boron toxicity in natural waters where it exceeds 2 mg/L.

  5. Characterizing and estimating noise in InSAR and InSAR time series with MODIS

    Science.gov (United States)

    Barnhart, William D.; Lohman, Rowena B.

    2013-01-01

    InSAR time series analysis is increasingly used to image subcentimeter displacement rates of the ground surface. The precision of InSAR observations is often affected by several noise sources, including spatially correlated noise from the turbulent atmosphere. Under ideal scenarios, InSAR time series techniques can substantially mitigate these effects; however, in practice the temporal distribution of InSAR acquisitions over much of the world exhibit seasonal biases, long temporal gaps, and insufficient acquisitions to confidently obtain the precisions desired for tectonic research. Here, we introduce a technique for constraining the magnitude of errors expected from atmospheric phase delays on the ground displacement rates inferred from an InSAR time series using independent observations of precipitable water vapor from MODIS. We implement a Monte Carlo error estimation technique based on multiple (100+) MODIS-based time series that sample date ranges close to the acquisitions times of the available SAR imagery. This stochastic approach allows evaluation of the significance of signals present in the final time series product, in particular their correlation with topography and seasonality. We find that topographically correlated noise in individual interferograms is not spatially stationary, even over short-spatial scales (<10 km). Overall, MODIS-inferred displacements and velocities exhibit errors of similar magnitude to the variability within an InSAR time series. We examine the MODIS-based confidence bounds in regions with a range of inferred displacement rates, and find we are capable of resolving velocities as low as 1.5 mm/yr with uncertainties increasing to ∼6 mm/yr in regions with higher topographic relief.

  6. Assessing ScanSAR Interferometry for Deformation Studies

    Science.gov (United States)

    Buckley, S. M.; Gudipati, K.

    2007-12-01

    There is a trend in civil satellite SAR mission design to implement an imaging strategy that incorporates both stripmap mode and ScanSAR imaging. This represents a compromise between high resolution data collection and a desire for greater spatial coverage and more frequent revisit times. However, mixed mode imaging can greatly reduce the number of stripmap images available for measuring subtle ground deformation. Although ScanSAR-ScanSAR and ScanSAR-stripmap repeat-pass interferometry have been demonstrated, these approaches are infrequently used for single interferogram formation and nonexistent for InSAR time series analysis. For future mission design, e.g., a dedicated US InSAR mission, the effect of various ScanSAR system parameter choices on InSAR time series analysis also remains unexplored. Our objective is to determine the utility of ScanSAR differential interferometry. We will demonstrate the use of ScanSAR interferograms for several previous deformation studies: localized and broad-scale urban land subsidence, tunneling, volcanic surface movements and several examples associated with the seismic cycle. We also investigate the effect of various ScanSAR burst synchronization levels on our ability to detect and make quality measurements of deformation. To avoid the issues associated with Envisat ScanSAR burst alignment and to exploit a decade of InSAR measurements, we simulate ScanSAR data by bursting (throwing away range lines of) ERS-1/2 data. All the burst mode datasets are processed using a Modified SPECAN algorithm. To investigate the effects of burst misalignment, a number of cases with varying degrees of burst overlap are considered. In particular, we look at phase decorrelation as a function of percentage of burst overlap. Coherence clearly reduces as the percentage of overlap decreases and we find a useful threshold of 40-70% burst overlap depending on the study site. In order to get a more generalized understanding for different surface conditions

  7. SARS-related perceptions in Hong Kong.

    Science.gov (United States)

    Lau, Joseph T F; Yang, Xilin; Pang, Ellie; Tsui, H Y; Wong, Eric; Wing, Yun Kwok

    2005-03-01

    To understand different aspects of community responses related to severe acute respiratory syndrome (SARS), 2 population-based, random telephone surveys were conducted in June 2003 and January 2004 in Hong Kong. More than 70% of respondents would avoid visiting hospitals or mainland China to avoid contracting SARS. Most respondents believed that SARS could be transmitted through droplets, fomites, sewage, and animals. More than 90% believed that public health measures were efficacious means of prevention; 40.4% believed that SARS would resurge in Hong Kong; and approximately equals 70% would then wear masks in public places. High percentages of respondents felt helpless, horrified, and apprehensive because of SARS. Approximately 16% showed signs of posttraumatic symptoms, and approximately equals 40% perceived increased stress in family or work settings. The general public in Hong Kong has been very vigilant about SARS but needs to be more psychologically prepared to face a resurgence of the epidemic.

  8. Toxicity and genotoxicity of the quaternary ammonium compound benzalkonium chloride (BAC) using Daphnia magna and Ceriodaphnia dubia as model systems

    International Nuclear Information System (INIS)

    Lavorgna, Margherita; Russo, Chiara; D'Abrosca, Brigida; Parrella, Alfredo; Isidori, Marina

    2016-01-01

    The toxicity and genotoxicity of the cationic surfactant benzalkonium chloride (BAC) were studied using Daphnia magna and Ceriodaphnia dubia as model systems. Acute and chronic toxicity testing were performed according to the international standard guidelines and the genotoxicity was detected through the comet assay on cells from whole organisms in vivo exposed. Acute effects occurred at concentrations in the order of tens of μg/L in D. magna and hundreds of μg/L in C. dubia. Chronic effects were found at one order of magnitude less than short-term effects maintaining the same difference in sensitivity between D. magna and C. dubia. BAC induced relevant DNA damage, in both cladocerans; the lowest adverse effect levels were 0.4 and 4 ng/L for D. magna and C. dubia, respectively. As these effective concentrations are far lower than BAC occurrence in surface waters (units of μg/L) a concerning environmental risk cannot be excluded. The findings of this study showed that D. magna and C. dubia, could be used as model organisms to detect acute and chronic toxicity as well as genotoxicity at the whole organism level. - Highlights: • Benzalkonium chloride chronic effect in C. dubia was found at dozens of μg/L. • The LOAEC detected by comet assay in D. magna is in the order of hundreds of pg/L. • D. magna and C. dubia are useful model organisms to detect toxicity and genotoxicity. - Benzalkonium chloride showed chronic toxicity and genotoxicity in Daphnia magna and Ceriodaphnia dubia at concentrations of environmental concern. Daphnids are useful model organisms.

  9. SAR: Stroke Authorship Recognition

    KAUST Repository

    Shaheen, Sara; Rockwood, Alyn; Ghanem, Bernard

    2015-01-01

    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.

  10. Trophic transfer potential of aluminium oxide nanoparticles using representative primary producer (Chlorella ellipsoides) and a primary consumer (Ceriodaphnia dubia)

    International Nuclear Information System (INIS)

    Pakrashi, Sunandan; Dalai, Swayamprava; Chandrasekaran, Natarajan; Mukherjee, Amitava

    2014-01-01

    Highlights: • Trophic transfer of alumina nanoparticles using Chlorella ellipsoides and Ceriodaphnia dubia. • Subtle alterations in the feeding behaviour of the daphnids. • Disruption the energy flow through the food chain. • Transmission electron microscopy validated the disrupted feeding behaviour. - Abstract: The transfer of nanoparticles through the food chain can lead to bioaccumulation and biomagnification resulting in a long term negative impact on the ecosystem functions. The primary objective of this study was evaluation of aluminium oxide nanoparticles transfer from primary producers to primary consumers. A simple set up consisting of a primary producer (Chlorella ellipsoides) and a primary consumer (Ceriodaphnia dubia) was used. Here, C. ellipsoides were exposed to the varying concentrations of the nanoparticles ranging from 20 to 120 μg/mL (196 to 1176 μM) for 48 h and the infested algal cells were used as the feed to C. dubia. The bioaccumulation of the nanoparticles into the daphnids was noted and the biomagnification factors were computed. The exposure was noted to cause subtle alterations in the feeding behaviour of the daphnids. This might have long term consequences in the energy flow through the food chain. The reproductive behaviour of the daphnids remained unaffected upon exposure to nanoparticle infested algal feed. Distinct observations at ultra-structural scale using transmission electron microscopy provided visual evidences for the disrupted feeding behaviour upon exposure to nanoparticle treated algae. Internalization of nanoparticle like inclusion bodies in the intracellular space of algae was also detected. The findings were further substantiated by a detailed analysis of hydrodynamic stability, bioavailability and dissolution of ions from the nanoparticles over the exposure period. Altogether, the study brings out the first of its kind of observation of trophic transfer potential/behaviour of aluminium oxide nanoparticles and

  11. Trophic transfer potential of aluminium oxide nanoparticles using representative primary producer (Chlorella ellipsoides) and a primary consumer (Ceriodaphnia dubia)

    Energy Technology Data Exchange (ETDEWEB)

    Pakrashi, Sunandan; Dalai, Swayamprava; Chandrasekaran, Natarajan; Mukherjee, Amitava, E-mail: amit.mookerjea@gmail.com

    2014-07-01

    Highlights: • Trophic transfer of alumina nanoparticles using Chlorella ellipsoides and Ceriodaphnia dubia. • Subtle alterations in the feeding behaviour of the daphnids. • Disruption the energy flow through the food chain. • Transmission electron microscopy validated the disrupted feeding behaviour. - Abstract: The transfer of nanoparticles through the food chain can lead to bioaccumulation and biomagnification resulting in a long term negative impact on the ecosystem functions. The primary objective of this study was evaluation of aluminium oxide nanoparticles transfer from primary producers to primary consumers. A simple set up consisting of a primary producer (Chlorella ellipsoides) and a primary consumer (Ceriodaphnia dubia) was used. Here, C. ellipsoides were exposed to the varying concentrations of the nanoparticles ranging from 20 to 120 μg/mL (196 to 1176 μM) for 48 h and the infested algal cells were used as the feed to C. dubia. The bioaccumulation of the nanoparticles into the daphnids was noted and the biomagnification factors were computed. The exposure was noted to cause subtle alterations in the feeding behaviour of the daphnids. This might have long term consequences in the energy flow through the food chain. The reproductive behaviour of the daphnids remained unaffected upon exposure to nanoparticle infested algal feed. Distinct observations at ultra-structural scale using transmission electron microscopy provided visual evidences for the disrupted feeding behaviour upon exposure to nanoparticle treated algae. Internalization of nanoparticle like inclusion bodies in the intracellular space of algae was also detected. The findings were further substantiated by a detailed analysis of hydrodynamic stability, bioavailability and dissolution of ions from the nanoparticles over the exposure period. Altogether, the study brings out the first of its kind of observation of trophic transfer potential/behaviour of aluminium oxide nanoparticles and

  12. 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...

  13. SARS: systematic review of treatment effects.

    Directory of Open Access Journals (Sweden)

    Lauren J Stockman

    2006-09-01

    Full Text Available BACKGROUND: The SARS outbreak of 2002-2003 presented clinicians with a new, life-threatening disease for which they had no experience in treating and no research on the effectiveness of treatment options. The World Health Organization (WHO expert panel on SARS treatment requested a systematic review and comprehensive summary of treatments used for SARS-infected patients in order to guide future treatment and identify priorities for research. METHODS AND FINDINGS: In response to the WHO request we conducted a systematic review of the published literature on ribavirin, corticosteroids, lopinavir and ritonavir (LPV/r, type I interferon (IFN, intravenous immunoglobulin (IVIG, and SARS convalescent plasma from both in vitro studies and in SARS patients. We also searched for clinical trial evidence of treatment for acute respiratory distress syndrome. Sources of data were the literature databases MEDLINE, EMBASE, BIOSIS, and the Cochrane Central Register of Controlled Trials (CENTRAL up to February 2005. Data from publications were extracted and evidence within studies was classified using predefined criteria. In total, 54 SARS treatment studies, 15 in vitro studies, and three acute respiratory distress syndrome studies met our inclusion criteria. Within in vitro studies, ribavirin, lopinavir, and type I IFN showed inhibition of SARS-CoV in tissue culture. In SARS-infected patient reports on ribavirin, 26 studies were classified as inconclusive, and four showed possible harm. Seven studies of convalescent plasma or IVIG, three of IFN type I, and two of LPV/r were inconclusive. In 29 studies of steroid use, 25 were inconclusive and four were classified as causing possible harm. CONCLUSIONS: Despite an extensive literature reporting on SARS treatments, it was not possible to determine whether treatments benefited patients during the SARS outbreak. Some may have been harmful. Clinical trials should be designed to validate a standard protocol for dosage

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. SAR Image Classification Based on Its Texture Features

    Institute of Scientific and Technical Information of China (English)

    LI Pingxiang; FANG Shenghui

    2003-01-01

    SAR images not only have the characteristics of all-ay, all-eather, but also provide object information which is different from visible and infrared sensors. However, SAR images have some faults, such as more speckles and fewer bands. The authors conducted the experiments of texture statistics analysis on SAR image features in order to improve the accuracy of SAR image interpretation.It is found that the texture analysis is an effective method for improving the accuracy of the SAR image interpretation.

  4. 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).

  5. 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.

  6. 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...

  7. PHARUS : PHased ARray Universal SAR

    NARCIS (Netherlands)

    Paquay, M.H.A.; Vermeulen, B.C.B.; Koomen, P.J.; Hoogeboom, P.; Snoeij, P.; Pouwels, H.

    1996-01-01

    In the Netherlands, a polarimetric C-band aircraft SAR (Synthetic Aperture Radar) has been developed. The project is called PHARUS, an acronm for PHased ARray Universal SAR. This instrument serves remote sensing applications. The antenna system contains 48 active modules (expandable to 96). A module

  8. Spaceborne Polarimetric SAR Interferometry: Performance Analysis and Mission Concepts

    Directory of Open Access Journals (Sweden)

    Shane R. Cloude

    2005-12-01

    Full Text Available We investigate multichannel imaging radar systems employing coherent combinations of polarimetry and interferometry (Pol-InSAR. Such systems are well suited for the extraction of bio- and geophysical parameters by evaluating the combined scattering from surfaces and volumes. This combination leads to several important differences between the design of Pol-InSAR sensors and conventional single polarisation SAR interferometers. We first highlight these differences and then investigate the Pol-InSAR performance of two proposed spaceborne SAR systems (ALOS/PalSAR and TerraSAR-L operating in repeat-pass mode. For this, we introduce the novel concept of a phase tube which enables (1 a quantitative assessment of the Pol-InSAR performance, (2 a comparison between different sensor configurations, and (3 an optimization of the instrument settings for different Pol-InSAR applications. The phase tube may hence serve as an interface between system engineers and application-oriented scientists. The performance analysis reveals major limitations for even moderate levels of temporal decorrelation. Such deteriorations may be avoided in single-pass sensor configurations and we demonstrate the potential benefits from the use of future bi- and multistatic SAR interferometers.

  9. SARS-related Perceptions in Hong Kong

    OpenAIRE

    Lau, Joseph T.F.; Yang, Xilin; Pang, Ellie; Tsui, H.Y.; Wong, Eric; Wing, Yun Kwok

    2005-01-01

    To understand different aspects of community responses related to severe acute respiratory syndrome (SARS), 2 population-based, random telephone surveys were conducted in June 2003 and January 2004 in Hong Kong. More than 70% of respondents would avoid visiting hospitals or mainland China to avoid contracting SARS. Most respondents believed that SARS could be transmitted through droplets, fomites, sewage, and animals. More than 90% believed that public health measures were efficacious means o...

  10. 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......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...

  11. How infectious is SARS virus

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. How infectious is SARS virus. Influenza: 1 patient infects ten people. SARS: 1 patient infects 2-4 people. Incubation period 10 days. Are there `silent´ cases ? Is quarantine enough ? How will it behave if and when it returns ?

  12. Imaging in severe acute respiratory syndrome (SARS)

    International Nuclear Information System (INIS)

    Antonio, G.E.; Wong, K.T.; Chu, W.C.W.; Hui, D.S.C.; Cheng, F.W.T.; Yuen, E.H.Y.; Chung, S.S.C.; Fok, T.F.; Sung, J.J.Y.; Ahuja, A.T.

    2003-01-01

    Severe acute respiratory syndrome (SARS) is a highly infectious disease caused by a novel coronavirus, and has become pandemic within a short period of time. Imaging plays an important role in the diagnosis, management and follow-up of patients with SARS. The current status of imaging in SARS is presented in this review

  13. PRF Ambiguity Detrmination for Radarsat ScanSAR System

    Science.gov (United States)

    Jin, Michael Y.

    1998-01-01

    PRF ambiguity is a potential problem for a spaceborne SAR operated at high frequencies. For a strip mode SAR, there were several approaches to solve this problem. This paper, however, addresses PRF ambiguity determination algorithms suitable for a burst mode SAR system such as the Radarsat ScanSAR. The candidate algorithms include the wavelength diversity algorithm, range look cross correlation algorithm, and multi-PRF algorithm.

  14. 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

  15. Life-cycle testing of receiving waters with Ceriodaphnia dubia

    International Nuclear Information System (INIS)

    Stewart, A.J.; Beane, B.K.

    1995-01-01

    Seven-day tests with Ceriodaphnia are commonly used to estimate the toxicity of effluents or receiving waters, but may yield no toxicity outcomes even when pollutants are present (a possible type II error). The authors conducted two sets of full life-cycle tests with C. dubia to (1) see if tests with longer exposure periods revealed evidence for toxicity that might not be evident from shorter tests, and (2) determine the relative importance of water quality versus food as factors influencing C. dubia reproduction. In the first set of tests, daphnids were reared in diluted mineral water (control), water from a stream impacted by coal fly-ash, or water from a mercury-contaminated retention basin. The second set of tests used water from the retention basin only, but this water was either filtered or not filtered, and food was either added or not added. C. dubia survival and reproduction did not differ much among the three waters in the first set of tests. However, both parameters were strongly affected by the filtering and food-addition treatments in the second set of tests. Thus, C. dubia seems to be moderately insensitive to general water-quality factors, but quite sensitive to food-related parameters. Regression analysis showed that the predictability of life-time reproduction of C. dubia from 7-day test results was low in five of six cases. The increase in predictability as a function of test duration also differed among water types (first set of tests), and among treatments (second set of tests). Thus, 7-day tests with C. dubia may be used to quantify water-quality problems, but it may not be possible to reliably extrapolate the results of such tests to longer time scales

  16. Monitoring Building Deformation with InSAR: Experiments and Validation

    Science.gov (United States)

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

    2016-01-01

    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. PMID:27999403

  17. Monitoring Building Deformation with InSAR: Experiments and Validation

    Directory of Open Access Journals (Sweden)

    Kui Yang

    2016-12-01

    Full Text Available 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.

  18. Horizontal distribution of Cladocera in a subtropical lake marginal to a river

    Directory of Open Access Journals (Sweden)

    Rafael Campanelli Mortari

    2015-09-01

    Full Text Available Various abiotic and biotic factors may determine the spatial distribution patterns of Cladocera in a lake. The aim of this study was to examine the horizontal distribution of Cladocera in a lake connected to a river during low and high water phases and the abiotic factors that determine variation in their populations. Microcrustaceans were collected in integrated samples at 40 sites distributed on a lake. The mean abundance of Cladocera was around five times higher in the low water phase than in the high water phase. Only populations of Bosmina hagmanni Stingelin, 1904 and Bosminopsis deitersi Richard, 1895 predominated in the low water phase, while in the high water phase, B. hagmanni, Ceriodaphnia cornuta f. rigaudi (Sars, 1896 Diaphanosoma spinulosum Herbst, 1975 and Moina micrura Kurz, 1875 predominated at some sampling stations. The majority of cladoceran species showed an aggregated distribution in the low water phase, except B. longirostris and D. fluviatile and, B. longirostris, the only ones which presented a uniform distribution pattern in the high water phase. Most of the aggregates of cladoceran species predominated in both the dry and rainy periods on the east side of the lake due to intense easterly wind. Some cladoceran populations formed isolate aggregates in other parts of the lake and near the lake-river connection site. Canonical Correspondence Analysis (CCA showed that the variables phosphorus, nitrogen and suspended matter (eutrophic conditions determined distinct patterns of horizontal distribution in some cladoceran populations at some stations in the low water phase, while in others, the patterns of horizontal distribution were determined by environmental conditions as alkalinity, pH, oxygen, depth and water transparency. In the high water phase, CCA revealed that phosphorus and water transparency were positive determining factors in the distribution of some cladoceran species, while alkalinity, depth and suspended matter

  19. Molecular mechanisms of severe acute respiratory syndrome (SARS

    Directory of Open Access Journals (Sweden)

    Zabel Peter

    2005-01-01

    Full Text Available Abstract Severe acute respiratory syndrome (SARS is a new infectious disease caused by a novel coronavirus that leads to deleterious pulmonary pathological features. Due to its high morbidity and mortality and widespread occurrence, SARS has evolved as an important respiratory disease which may be encountered everywhere in the world. The virus was identified as the causative agent of SARS due to the efforts of a WHO-led laboratory network. The potential mutability of the SARS-CoV genome may lead to new SARS outbreaks and several regions of the viral genomes open reading frames have been identified which may contribute to the severe virulence of the virus. With regard to the pathogenesis of SARS, several mechanisms involving both direct effects on target cells and indirect effects via the immune system may exist. Vaccination would offer the most attractive approach to prevent new epidemics of SARS, but the development of vaccines is difficult due to missing data on the role of immune system-virus interactions and the potential mutability of the virus. Even in a situation of no new infections, SARS remains a major health hazard, as new epidemics may arise. Therefore, further experimental and clinical research is required to control the disease.

  20. 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.

  1. Dynamic changes of serum SARS-Coronavirus IgG, pulmonary function and radiography in patients recovering from SARS after hospital discharge

    Directory of Open Access Journals (Sweden)

    Chen Liangan

    2005-01-01

    Full Text Available Abstract Objective The intent of this study was to examine the recovery of individuals who had been hospitalized for severe acute respiratory syndrome (SARS in the year following their discharge from the hospital. Parameters studied included serum levels of SARS coronavirus (SARS-CoV IgG antibody, tests of lung function, and imaging data to evaluate changes in lung fibrosis. In addition, we explored the incidence of femoral head necrosis in some of the individuals recovering from SARS. Methods The subjects of this study were 383 clinically diagnosed SARS patients in Beijing, China. They were tested regularly for serum levels of SARS-CoV IgG antibody and lung function and were given chest X-rays and/or high resolution computerized tomography (HRCT examinations at the Chinese PLA General Hospital during the 12 months that followed their release from the hospital. Those individuals who were found to have lung diffusion abnormities (transfer coefficient for carbon monoxide [DLCO] Findings Of all the subjects, 81.2% (311 of 383 patients tested positive for serum SARS-CoV IgG. Of those testing positive, 27.3% (85 of 311 patients were suffering from lung diffusion abnormities (DLCO Interpretation The lack of sero-positive SARS-CoV in some individuals suggests that there may have been some misdiagnosed cases among the subjects included in this study. Of those testing positive, the serum levels of SARS-CoV IgG antibody decreased significantly during the 12 months after hospital discharge. Additionally, we found that the individuals who had lung fibrosis showed some spontaneous recovery. Finally, some of the subjects developed femoral head necrosis.

  2. Nano(Q)SAR: Challenges, pitfalls and perspectives.

    Science.gov (United States)

    Tantra, Ratna; Oksel, Ceyda; Puzyn, Tomasz; Wang, Jian; Robinson, Kenneth N; Wang, Xue Z; Ma, Cai Y; Wilkins, Terry

    2015-01-01

    Regulation for nanomaterials is urgently needed, and the drive to adopt an intelligent testing strategy is evident. Such a strategy will not only provide economic benefits but will also reduce moral and ethical concerns arising from animal testing. For regulatory purposes, such an approach is promoted by REACH, particularly the use of quantitative structure-activity relationships [(Q)SAR] as a tool for the categorisation of compounds according to their physicochemical and toxicological properties. In addition to compounds, (Q)SAR has also been applied to nanomaterials in the form of nano(Q)SAR. Although (Q)SAR in chemicals is well established, nano(Q)SAR is still in early stages of development and its successful uptake is far from reality. This article aims to identify some of the pitfalls and challenges associated with nano-(Q)SARs in relation to the categorisation of nanomaterials. Our findings show clear gaps in the research framework that must be addressed if we are to have reliable predictions from such models. Three major barriers were identified: the need to improve quality of experimental data in which the models are developed from, the need to have practical guidelines for the development of the nano(Q)SAR models and the need to standardise and harmonise activities for the purpose of regulation. Of these three, the first, i.e. the need to improve data quality requires immediate attention, as it underpins activities associated with the latter two. It should be noted that the usefulness of data in the context of nano-(Q)SAR modelling is not only about the quantity of data but also about the quality, consistency and accessibility of those data.

  3. Playback system designed for X-Band SAR

    International Nuclear Information System (INIS)

    Yuquan, Liu; Changyong, Dou

    2014-01-01

    SAR(Synthetic Aperture Radar) has extensive application because it is daylight and weather independent. In particular, X-Band SAR strip map, designed by Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, provides high ground resolution images, at the same time it has a large spatial coverage and a short acquisition time, so it is promising in multi-applications. When sudden disaster comes, the emergency situation acquires radar signal data and image as soon as possible, in order to take action to reduce loss and save lives in the first time. This paper summarizes a type of X-Band SAR playback processing system designed for disaster response and scientific needs. It describes SAR data workflow includes the payload data transmission and reception process. Playback processing system completes signal analysis on the original data, providing SAR level 0 products and quick image. Gigabit network promises radar signal transmission efficiency from recorder to calculation unit. Multi-thread parallel computing and ping pong operation can ensure computation speed. Through gigabit network, multi-thread parallel computing and ping pong operation, high speed data transmission and processing meet the SAR radar data playback real time requirement

  4. Playback system designed for X-Band SAR

    Science.gov (United States)

    Yuquan, Liu; Changyong, Dou

    2014-03-01

    SAR(Synthetic Aperture Radar) has extensive application because it is daylight and weather independent. In particular, X-Band SAR strip map, designed by Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, provides high ground resolution images, at the same time it has a large spatial coverage and a short acquisition time, so it is promising in multi-applications. When sudden disaster comes, the emergency situation acquires radar signal data and image as soon as possible, in order to take action to reduce loss and save lives in the first time. This paper summarizes a type of X-Band SAR playback processing system designed for disaster response and scientific needs. It describes SAR data workflow includes the payload data transmission and reception process. Playback processing system completes signal analysis on the original data, providing SAR level 0 products and quick image. Gigabit network promises radar signal transmission efficiency from recorder to calculation unit. Multi-thread parallel computing and ping pong operation can ensure computation speed. Through gigabit network, multi-thread parallel computing and ping pong operation, high speed data transmission and processing meet the SAR radar data playback real time requirement.

  5. Molecular Evidence for the Hybrid Origin of Ilex dabieshanensis (Aquifoliaceae.

    Directory of Open Access Journals (Sweden)

    Lin Shi

    Full Text Available Ilex, the largest genus of dioecious woody plants, is a good study system to assess the role of hybridization in speciation and evolution. Ilex dabieshanensis, a tree endemic to Dabieshan Mountains region, was initially described as a new species. Based on morphological intermediacy and sympatric distribution with its putative parental species, I. cornuta and I. latifolia, we proposed it as a natural hybrid between them. In this study, we sequenced one chloroplast intergenic spacer (trnH-psbA and two nuclear genes (gapC and nepGS in I. dabieshanensis and its putative parental species to test the hybrid origin hypothesis. Our results showed that there were one to two differentially fixed sequence differences between I. cornuta and I. latifolia at the two nuclear genes. Twelve of the 14 individuals of I. dabieshanensis exhibited additivity in chromatograms on these differentially fixed sites at both nuclear genes, and the remaining two exhibited additivity in chromatograms on the fixed site at only the nepGS gene. Except one haplotype of I. cornuta at the nepGS gene, all of the haplotypes of I. cornuta at the two nuclear genes were well separated from those of I. latifolia, and most haplotypes of I. dabieshanensis were shared with those of I. cornuta and I. latifolia. Phylogenetic analysis of these haplotypes was largely consistent with haplotype network analysis. I. cornuta and I. latifolia differed by two nucleotide substitutions in the chloroplast intergenic spacer, and 12 individuals of I. dabieshanensis had the same sequences as I. latifolia, while the remaining two were identical with I. cornuta. The molecular data provide convincing evidence for the hybrid origin of I. dabieshanensis and asymmetrical direction of hybridization. One haplotype of I. cornuta at the nepGS gene was nested with those of I. latifolia, indicating introgression to I. cornuta.

  6. 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.

    < 2m and the zero-crossing period during the satellite overpass is small (< 6s, �O�O < 60m). We therefore utilized the visit of one of the authors (Sarma) to the Southampton Oceanographic Centre, U.K., to procure two ERS-1 digital image mode SAR...-dimensional FFT as well as a computer program for downloading SAR data from CCT. Finally we owe a debt of gratitude to J C da Silva, Southampton Oceanographic Centre, U K for sharing some of his SAR data with us. References Allan T. D. (Ed) (1983...

  7. 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.

    Gaussian smoothed SAR image spectra have been evaluated from 512 x 512 pixel subscenes of image mode ERS-1 SAR scenes off Goa, Visakhapatnam, Paradeep and Portugal. The two recently acquired scenes off Portugal showed the signature of swell...

  8. Image based SAR product simulation for analysis

    Science.gov (United States)

    Domik, G.; Leberl, F.

    1987-01-01

    SAR product simulation serves to predict SAR image gray values for various flight paths. Input typically consists of a digital elevation model and backscatter curves. A new method is described of product simulation that employs also a real SAR input image for image simulation. This can be denoted as 'image-based simulation'. Different methods to perform this SAR prediction are presented and advantages and disadvantages discussed. Ascending and descending orbit images from NASA's SIR-B experiment were used for verification of the concept: input images from ascending orbits were converted into images from a descending orbit; the results are compared to the available real imagery to verify that the prediction technique produces meaningful image data.

  9. Reverse genetics of SARS-related coronavirus using vaccinia virus-based recombination.

    Directory of Open Access Journals (Sweden)

    Sjoerd H E van den Worm

    Full Text Available 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.

  10. Spaceborne Differential SAR Interferometry: Data Analysis Tools for Deformation Measurement

    Directory of Open Access Journals (Sweden)

    Michele Crosetto

    2011-02-01

    Full Text Available This paper is focused on spaceborne Differential Interferometric SAR (DInSAR for land deformation measurement and monitoring. In the last two decades several DInSAR data analysis procedures have been proposed. The objective of this paper is to describe the DInSAR data processing and analysis tools developed at the Institute of Geomatics in almost ten years of research activities. Four main DInSAR analysis procedures are described, which range from the standard DInSAR analysis based on a single interferogram to more advanced Persistent Scatterer Interferometry (PSI approaches. These different procedures guarantee a sufficient flexibility in DInSAR data processing. In order to provide a technical insight into these analysis procedures, a whole section discusses their main data processing and analysis steps, especially those needed in PSI analyses. A specific section is devoted to the core of our PSI analysis tools: the so-called 2+1D phase unwrapping procedure, which couples a 2D phase unwrapping, performed interferogram-wise, with a kind of 1D phase unwrapping along time, performed pixel-wise. In the last part of the paper, some examples of DInSAR results are discussed, which were derived by standard DInSAR or PSI analyses. Most of these results were derived from X-band SAR data coming from the TerraSAR-X and CosmoSkyMed sensors.

  11. 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.

  12. Pyrimidine and nucleoside gamma-esters of L-Glu-Sar

    DEFF Research Database (Denmark)

    Eriksson, André H; Elm, Peter L; Begtrup, Mikael

    2005-01-01

    -tetrahydrofuran-3-yl ester)-Sar (I), l-Glu(thymine-1-yl-methyl ester)-Sar (II) and l-Glu(acyclothymidine)-Sar (III) were synthesised and in vitro stability was studied in various aqueous and biological media. Affinity to and translocation via hPEPT1 was investigated in mature Caco-2 cell monolayers, grown......The aim of the present study was to improve the synthetic pathway of bioreversible dipeptide derivatives as well as evaluate the potential of using l-Glu-Sar as a pro-moiety for delivering three newly synthesised nucleoside and pyrimidine l-Glu-Sar derivatives. l-Glu(trans-2-thymine-1-yl...

  13. Use of SAR data for proliferation monitoring

    International Nuclear Information System (INIS)

    Lafitte, M.; Robin, J.P.

    2013-01-01

    Synthetic Aperture Radar (SAR) is an active and coherent system. SAR images are complex data which contain both amplitude and phase information. The analysis of single SAR data required a very good experience and a good understanding of SAR geometry regarding layover, shadowing, texture and speckle. Image analyst can depicts and describes most of the facilities related to nuclear proliferation and weapons of mass destruction (WMD). The Amplitude Change Detection (ACD) technique consists of a combination of two or three SAR amplitude data acquired with similar orbit and frequency parameters on different dates. That technique provides a very good overview of the changes and particularly regarding vehicles activity and constructions ongoing within the area of interest over the monitoring period. One of the particularities of the SAR systems is to be coherent. The phase of a single image is not exploitable. Thus when two or more SAR data have been acquired with identical orbit and frequency parameters, the phases shift are indicators of changes such as structural changes, terrain subsidence or motion. The Multi-Temporal Coherence (MTC) product merged the two type of information previously detailed: the ACD and coherence analysis. It consists of the combination of two amplitude images and the corresponding coherence computed image. The MTC image may highlights changes between two states of a target which on the ACD analysis appeared unchanged. EUSC uses the difference interferometry techniques in order to estimate volumes that have changed between two acquisition dates. The paper is followed by the slides of the presentation. (A.C.)

  14. SAR and LIDAR fusion: experiments and applications

    Science.gov (United States)

    Edwards, Matthew C.; Zaugg, Evan C.; Bradley, Joshua P.; Bowden, Ryan D.

    2013-05-01

    In recent years ARTEMIS, Inc. has developed a series of compact, versatile Synthetic Aperture Radar (SAR) systems which have been operated on a variety of small manned and unmanned aircraft. The multi-frequency-band SlimSAR has demonstrated a variety of capabilities including maritime and littoral target detection, ground moving target indication, polarimetry, interferometry, change detection, and foliage penetration. ARTEMIS also continues to build upon the radar's capabilities through fusion with other sensors, such as electro-optical and infrared camera gimbals and light detection and ranging (LIDAR) devices. In this paper we focus on experiments and applications employing SAR and LIDAR fusion. LIDAR is similar to radar in that it transmits a signal which, after being reflected or scattered by a target area, is recorded by the sensor. The differences are that a LIDAR uses a laser as a transmitter and optical sensors as a receiver, and the wavelengths used exhibit a very different scattering phenomenology than the microwaves used in radar, making SAR and LIDAR good complementary technologies. LIDAR is used in many applications including agriculture, archeology, geo-science, and surveying. Some typical data products include digital elevation maps of a target area and features and shapes extracted from the data. A set of experiments conducted to demonstrate the fusion of SAR and LIDAR data include a LIDAR DEM used in accurately processing the SAR data of a high relief area (mountainous, urban). Also, feature extraction is used in improving geolocation accuracy of the SAR and LIDAR data.

  15. 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.

  16. Polarimetric SAR interferometry-based decomposition modelling for reliable scattering retrieval

    Science.gov (United States)

    Agrawal, Neeraj; Kumar, Shashi; Tolpekin, Valentyn

    2016-05-01

    Fully Polarimetric SAR (PolSAR) data is used for scattering information retrieval from single SAR resolution cell. Single SAR resolution cell may contain contribution from more than one scattering objects. Hence, single or dual polarized data does not provide all the possible scattering information. So, to overcome this problem fully Polarimetric data is used. It was observed in previous study that fully Polarimetric data of different dates provide different scattering values for same object and coefficient of determination obtained from linear regression between volume scattering and aboveground biomass (AGB) shows different values for the SAR dataset of different dates. Scattering values are important input elements for modelling of forest aboveground biomass. In this research work an approach is proposed to get reliable scattering from interferometric pair of fully Polarimetric RADARSAT-2 data. The field survey for data collection was carried out for Barkot forest during November 10th to December 5th, 2014. Stratified random sampling was used to collect field data for circumference at breast height (CBH) and tree height measurement. Field-measured AGB was compared with the volume scattering elements obtained from decomposition modelling of individual PolSAR images and PolInSAR coherency matrix. Yamaguchi 4-component decomposition was implemented to retrieve scattering elements from SAR data. PolInSAR based decomposition was the great challenge in this work and it was implemented with certain assumptions to create Hermitian coherency matrix with co-registered polarimetric interferometric pair of SAR data. Regression analysis between field-measured AGB and volume scattering element obtained from PolInSAR data showed highest (0.589) coefficient of determination. The same regression with volume scattering elements of individual SAR images showed 0.49 and 0.50 coefficients of determination for master and slave images respectively. This study recommends use of

  17. 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.

  18. SARS – Koch´Postulates proved.

    Indian Academy of Sciences (India)

    SARS – Koch´Postulates proved. Novel coronavirus identified from fluids of patients. Virus cultured in Vero cell line. Sera of patients have antibodies to virus. Cultured virus produces disease in Macaque monkeys. -produces specific immune response; -isolated virus is SARS CoV; -pathology similar to human.

  19. 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.

  20. SAR system development for UAV multicopter platforms

    OpenAIRE

    Escartin Martínez, Antonio

    2015-01-01

    SAR system development for UAV multicopter platforms This thesis describes the optimization of a synthetic aperture radar (SAR) at X-band and its integration into an unmanned aerial vehicle (UAV) of type octocopter. For such optimization the SAR system functionality was extended from singlepol to fulpol and it has been optimized at hardware level in order to improve its quality against noise figure. After its integration into the octocopter platform, its features has been used in order to ...

  1. Novel Polarimetric SAR Interferometry Algorithms, Phase I

    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...

  2. PHARUS: A C-band Airborne SAR

    NARCIS (Netherlands)

    Hoogeboom, P.; Koomen, P.J.; Pouwels, H.; Snoeij, P.

    1990-01-01

    In The Netherlands a plan to design aircraft and build a polarimetric C-band SAR system of a novel design, called PHARUS (PHased Array Universal SAR) is carried out by three institutes. These institutes are the Physics and Electronics Laboratory TNO in The Hague (prime contractor and project

  3. Life-cycle testing of receiving waters with Ceriodaphnia dubia

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, A.J.; Konetsky, B.K.

    1996-12-31

    Seven-day tests with Ceriodaphnia dubia are commonly used to estimate toxicity of effluents or receiving waters but can sometimes yield {open_quotes}no toxicity{close_quotes} outcomes even if pollutants are present. We conducted two sets of full life-cycle tests with C. dubia to (1) see if tests with longer exposure periods would reveal evidence for toxicity that might not be evident from 7-day tests, and (2) determine the relative importance of water quality versus food as factors influencing C. dubia reproduction. In the first set of tests, C. dubia was reared in diluted mineral water (negative control), water from a stream impacted by coal fly-ash, or water from a retention basin containing sediments contaminated with mercury, other metals and polychlorinated biphenyls. The second set of tests used water from the retention basin only, but this water was either filtered or not filtered, and food was either added or not added, prior to testing. C. dubia survival and reproduction did not differ much among the three water types in the first set of tests, but these two parameters were strongly affected by the filtering and food-addition treatments in the second set of tests. Thus, C. dubia appeared to be relatively insensitive to general water-quality factors, but quite sensitive to food-related factors. Regression analyses showed that the predictability of life-time reproduction by C. dubia from the results of 7-day tests was very low (R{sup 2}< 0.35) in five of the six experiments. The increase in predictability as a function of test duration also differed among water types in the first set of tests, and among treatments in the second set of tests. Thus, 7-day tests with C. dubia may be used to quantify water-quality problems, but it may not be possible to reliably extrapolate the results of these tests to longer time scales.

  4. Accelerated Scientific InSAR Processing, Phase I

    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...

  5. Polarimetric SAR image classification based on discriminative dictionary learning model

    Science.gov (United States)

    Sang, Cheng Wei; Sun, Hong

    2018-03-01

    Polarimetric SAR (PolSAR) image classification is one of the important applications of PolSAR remote sensing. It is a difficult high-dimension nonlinear mapping problem, the sparse representations based on learning overcomplete dictionary have shown great potential to solve such problem. The overcomplete dictionary plays an important role in PolSAR image classification, however for PolSAR image complex scenes, features shared by different classes will weaken the discrimination of learned dictionary, so as to degrade classification performance. In this paper, we propose a novel overcomplete dictionary learning model to enhance the discrimination of dictionary. The learned overcomplete dictionary by the proposed model is more discriminative and very suitable for PolSAR classification.

  6. 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

  7. Forest parameter estimation using polarimetric SAR interferometry techniques at low frequencies

    International Nuclear Information System (INIS)

    Lee, Seung-Kuk

    2013-01-01

    Polarimetric Synthetic Aperture Radar Interferometry (Pol-InSAR) is an active radar remote sensing technique based on the coherent combination of both polarimetric and interferometric observables. The Pol-InSAR technique provided a step forward in quantitative forest parameter estimation. In the last decade, airborne SAR experiments evaluated the potential of Pol-InSAR techniques to estimate forest parameters (e.g., the forest height and biomass) with high accuracy over various local forest test sites. This dissertation addresses the actual status, potentials and limitations of Pol-InSAR inversion techniques for 3-D forest parameter estimations on a global scale using lower frequencies such as L- and P-band. The multi-baseline Pol-InSAR inversion technique is applied to optimize the performance with respect to the actual level of the vertical wave number and to mitigate the impact of temporal decorrelation on the Pol-InSAR forest parameter inversion. Temporal decorrelation is a critical issue for successful Pol-InSAR inversion in the case of repeat-pass Pol-InSAR data, as provided by conventional satellites or airborne SAR systems. Despite the limiting impact of temporal decorrelation in Pol-InSAR inversion, it remains a poorly understood factor in forest height inversion. Therefore, the main goal of this dissertation is to provide a quantitative estimation of the temporal decorrelation effects by using multi-baseline Pol-InSAR data. A new approach to quantify the different temporal decorrelation components is proposed and discussed. Temporal decorrelation coefficients are estimated for temporal baselines ranging from 10 minutes to 54 days and are converted to height inversion errors. In addition, the potential of Pol-InSAR forest parameter estimation techniques is addressed and projected onto future spaceborne system configurations and mission scenarios (Tandem-L and BIOMASS satellite missions at L- and P-band). The impact of the system parameters (e.g., bandwidth

  8. 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

  9. 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.

  10. Mapping mountain meadow with high resolution and polarimetric SAR data

    International Nuclear Information System (INIS)

    Tian, Bangsen; Li, Zhen; Xu, Juan; Fu, Sitao; Liu, Jiuli

    2014-01-01

    This paper presents a method to map the large grassland in the eastern margin of the Tibetan Plateau with the high resolution polarimetric SAR (PolSAR) imagery. When PolSAR imagery is used for land cover classification, the brightness of a SAR image is affected by topography due to varying projection between ground and image coordinates. The objective of this paper is twofold: (1) we first extend the theory of SAR terrain correction to the polarimetric case, to utilize the entire available polarimetric signature, where correction is performed explicitly based on a matrix format like covariance matrix. (2) Next, the orthoectified PolSAR is applied to classify mountain meadow and investigate the potential of PolSAR in mapping grassland. In this paper, the gamma naught radiometric correction estimates the local illuminated area at each grid point in the radar geometry. Then, each element of the coherency matrix is divided by the local area to produce a polarimetric product. Secondly, the impact of radiometric correction upon classification accuracy is investigated. A supervised classification is performed on the orthorectified Radarsat-2 PolSAR to map the spatial distribution of meadow and evaluate monitoring capabilities of mountain meadow

  11. 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...

  12. Bioaccumulation of Fe2O3(magnetic) nanoparticles in Ceriodaphnia dubia

    International Nuclear Information System (INIS)

    Hu Ji; Wang Demin; Wang Jiangtao; Wang Jianmin

    2012-01-01

    While nano-Fe 2 O 3 (magnetic) is generally considered non-toxic, it could serve as a carrier of other toxic chemicals such as As(V) and enhance their toxicity. The bioaccumulation of nano-Fe 2 O 3 (m) with different exposure times, NP concentrations, and pH conditions was investigated using Ceriodaphnia dubia (C. dubia) as the model organism. Under natural pH conditions, C. dubia significantly accumulated nano-Fe 2 O 3 (m) in the gut, with the maximum accumulation being achieved after 6 h of exposure. The concentration of nano-Fe 2 O 3 also impacted its accumulation, with the maximum uptake occurring at 20 mg/L or more. In addition, the highest bioaccumulation occurred in a pH range of 7–8 where the highest feeding rate was reported, confirming that the ingestion of NPs is the main route of nano-Fe 2 O 3 (m) bioaccumulation. In a clean environment without NPs, depuration of nano-Fe 2 O 3 (m) occurred, and food addition accelerated the depuration process. - Highlights: ► Nano-Fe 2 O 3 (m) enhances the toxicity of As(V). ► C. dubia significantly accumulate nano-Fe 2 O 3 (m) through ingestion. ► The bioaccumulation of nano-Fe 2 O 3 (m) is affected by time, NP concentration, and pH. ► Food addition accelerates the depuration process of accumulated nano-Fe 2 O 3 (m). - Nano-Fe 2 O 3 (m) could enhance the toxicity of As(V) due to the significant accumulation of nano-Fe 2 O 3 (m) along with sorbed As(V) by C. dubia through ingestion.

  13. 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.

  14. Improved SAR Image Coregistration Using Pixel-Offset Series

    KAUST Repository

    Wang, Teng; Jonsson, Sigurjon; Hanssen, Ramon F.

    2014-01-01

    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.

  15. URBAN MODELLING PERFORMANCE OF NEXT GENERATION SAR MISSIONS

    Directory of Open Access Journals (Sweden)

    U. G. Sefercik

    2017-09-01

    Full Text Available 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.

  16. InSAR deformation monitoring of high risk landslides

    Science.gov (United States)

    Singhroy, V.; Li, J.

    2013-05-01

    During the past year there were at least twenty five media reports of landslides and seismic activities some fatal, occurring in various areas in Canada. These high risk geohazards sites requires high resolution monitoring both spatially and temporally for mitigation purposes, since they are near populated areas and energy, transportation and communication corridors. High resolution air photos, lidar and satellite images are quite common in areas where the landslides can be fatal. Radar interferometry (InSAR) techniques using images from several radar satellites are increasingly being used in slope stability assessment. This presentation provides examples of using high-resolution (1-3m) frequent revisits InSAR techniques from RADARSAT 2 and TerraSAR X to monitor several types of high-risk landslides affecting transportation and energy corridors and populated areas. We have analyses over 200 high resolution InSAR images over a three year period on geologically different landslides. The high-resolution InSAR images are effective in characterizing differential motion within these low velocity landslides. The low velocity landslides become high risk during the active wet spring periods. The wet soils are poor coherent targets and corner reflectors provide an effective means of InSAR monitoring the slope activities.

  17. 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...

  18. hPEPT1 Affinity and Translocation of Selected Gln-Sar and Glu-Sar Dipeptide Derivatives

    DEFF Research Database (Denmark)

    Eriksson, A. H.; Elm, Peter L.; Begtrup, Mikael

    2005-01-01

    using 14C-labeled Gly-Sar. Translocation was measured as fluorescence ratios induced by the substrates using the fluorescent probe BCECF and an epifluorescence microscope setup. All compounds showed high affinity to hPEPT1, but only the amides l-Gln(N,N-dimethyl)-Sar and l-Gln(N-piperidinyl)-Sar were...... been suggested. However, these are not necessarily predictive of compounds that are actually translocated by hPEPT1. More information on affinity to and translocation via hPEPT1 of side-chain-modified dipeptides may be gained by conducting a study of selected dipeptide derivatives with variety in size...... translocated by hPEPT1. hPEPT1 is very susceptible to modifications of the N-terminal amino acid side chain of dipeptidomimetic substrates, in terms of achieving compounds with high affinity for the transporter. However, as affinity is not predictive of translocation, derivatization in this position must...

  19. Flood extent and water level estimation from SAR using data-model integration

    Science.gov (United States)

    Ajadi, O. A.; Meyer, F. J.

    2017-12-01

    Synthetic Aperture Radar (SAR) images have long been recognized as a valuable data source for flood mapping. Compared to other sources, SAR's weather and illumination independence and large area coverage at high spatial resolution supports reliable, frequent, and detailed observations of developing flood events. Accordingly, SAR has the potential to greatly aid in the near real-time monitoring of natural hazards, such as flood detection, if combined with automated image processing. This research works towards increasing the reliability and temporal sampling of SAR-derived flood hazard information by integrating information from multiple SAR sensors and SAR modalities (images and Interferometric SAR (InSAR) coherence) and by combining SAR-derived change detection information with hydrologic and hydraulic flood forecast models. First, the combination of multi-temporal SAR intensity images and coherence information for generating flood extent maps is introduced. The application of least-squares estimation integrates flood information from multiple SAR sensors, thus increasing the temporal sampling. SAR-based flood extent information will be combined with a Digital Elevation Model (DEM) to reduce false alarms and to estimate water depth and flood volume. The SAR-based flood extent map is assimilated into the Hydrologic Engineering Center River Analysis System (Hec-RAS) model to aid in hydraulic model calibration. The developed technology is improving the accuracy of flood information by exploiting information from data and models. It also provides enhanced flood information to decision-makers supporting the response to flood extent and improving emergency relief efforts.

  20. The experience of SARS-related stigma at Amoy Gardens.

    Science.gov (United States)

    Lee, Sing; Chan, Lydia Y Y; Chau, Annie M Y; Kwok, Kathleen P S; Kleinman, Arthur

    2005-11-01

    Severe Acute Respiratory Syndrome (SARS) possesses characteristics that render it particularly prone to stigmatization. SARS-related stigma, despite its salience for public health and stigma research, has had little examination. This study combines survey and case study methods to examine subjective stigma among residents of Amoy Gardens (AG), the first officially recognized site of community outbreak of SARS in Hong Kong. A total of 903 residents of AG completed a self-report questionnaire derived from two focus groups conducted toward the end of the 3-month outbreak. Case studies of two residents who lived in Block E, the heart of the SARS epidemic at AG, complement the survey data. Findings show that stigma affected most residents and took various forms of being shunned, insulted, marginalized, and rejected in the domains of work, interpersonal relationships, use of services and schooling. Stigma was also associated with psychosomatic distress. Residents' strategies for diminishing stigma varied with gender, age, education, occupation, and proximity to perceived risk factors for SARS such as residential location, previous SARS infection and the presence of ex-SARS household members. Residents attributed stigma to government mismanagement, contagiousness of the mysterious SARS virus, and alarmist media reporting. Stigma clearly decreased, but never completely disappeared, after the outbreak. The findings confirm and add to existing knowledge on the varied origins, correlates, and impacts of stigma. They also highlight the synergistic roles of inconsistent health policy responses and risk miscommunication by the media in rapidly amplifying stigma toward an unfamiliar illness. While recognizing the intrinsically stigmatizing nature of public health measures to control SARS, we recommend that a consistent inter-sectoral approach is needed to minimize stigma and to make an effective health response to future outbreaks.

  1. Estimating Elevation Angles From SAR Crosstalk

    Science.gov (United States)

    Freeman, Anthony

    1994-01-01

    Scheme for processing polarimetric synthetic-aperture-radar (SAR) image data yields estimates of elevation angles along radar beam to target resolution cells. By use of estimated elevation angles, measured distances along radar beam to targets (slant ranges), and measured altitude of aircraft carrying SAR equipment, one can estimate height of target terrain in each resolution cell. Monopulselike scheme yields low-resolution topographical data.

  2. SAR Study of Mobile Phones as a function of Antenna Q

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Svendsen, Simon; Jagielski, Ole

    2015-01-01

    density associated with high-Q antennas. The higher energy stored in the electric and magnetic near-field components can result in higher SAR. Hence, SAR study of high-Q antennas is necessary which, if not addressed, might not comply with the SAR safety guidelines. In this paper, SAR as a function...

  3. 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...

  4. High-Level Performance Modeling of SAR Systems

    Science.gov (United States)

    Chen, Curtis

    2006-01-01

    SAUSAGE (Still Another Utility for SAR Analysis that s General and Extensible) is a computer program for modeling (see figure) the performance of synthetic- aperture radar (SAR) or interferometric synthetic-aperture radar (InSAR or IFSAR) systems. The user is assumed to be familiar with the basic principles of SAR imaging and interferometry. Given design parameters (e.g., altitude, power, and bandwidth) that characterize a radar system, the software predicts various performance metrics (e.g., signal-to-noise ratio and resolution). SAUSAGE is intended to be a general software tool for quick, high-level evaluation of radar designs; it is not meant to capture all the subtleties, nuances, and particulars of specific systems. SAUSAGE was written to facilitate the exploration of engineering tradeoffs within the multidimensional space of design parameters. Typically, this space is examined through an iterative process of adjusting the values of the design parameters and examining the effects of the adjustments on the overall performance of the system at each iteration. The software is designed to be modular and extensible to enable consideration of a variety of operating modes and antenna beam patterns, including, for example, strip-map and spotlight SAR acquisitions, polarimetry, burst modes, and squinted geometries.

  5. Automatic Coregistration for Multiview SAR Images in Urban Areas

    Science.gov (United States)

    Xiang, Y.; Kang, W.; Wang, F.; You, H.

    2017-09-01

    Due to the high resolution property and the side-looking mechanism of SAR sensors, complex buildings structures make the registration of SAR images in urban areas becomes very hard. In order to solve the problem, an automatic and robust coregistration approach for multiview high resolution SAR images is proposed in the paper, which consists of three main modules. First, both the reference image and the sensed image are segmented into two parts, urban areas and nonurban areas. Urban areas caused by double or multiple scattering in a SAR image have a tendency to show higher local mean and local variance values compared with general homogeneous regions due to the complex structural information. Based on this criterion, building areas are extracted. After obtaining the target regions, L-shape structures are detected using the SAR phase congruency model and Hough transform. The double bounce scatterings formed by wall and ground are shown as strong L- or T-shapes, which are usually taken as the most reliable indicator for building detection. According to the assumption that buildings are rectangular and flat models, planimetric buildings are delineated using the L-shapes, then the reconstructed target areas are obtained. For the orignal areas and the reconstructed target areas, the SAR-SIFT matching algorithm is implemented. Finally, correct corresponding points are extracted by the fast sample consensus (FSC) and the transformation model is also derived. The experimental results on a pair of multiview TerraSAR images with 1-m resolution show that the proposed approach gives a robust and precise registration performance, compared with the orignal SAR-SIFT method.

  6. 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.

  7. Relevant Scatterers Characterization in SAR Images

    Science.gov (United States)

    Chaabouni, Houda; Datcu, Mihai

    2006-11-01

    Recognizing scenes in a single look meter resolution Synthetic Aperture Radar (SAR) images, requires the capability to identify relevant signal signatures in condition of variable image acquisition geometry, arbitrary objects poses and configurations. Among the methods to detect relevant scatterers in SAR images, we can mention the internal coherence. The SAR spectrum splitted in azimuth generates a series of images which preserve high coherence only for particular object scattering. The detection of relevant scatterers can be done by correlation study or Independent Component Analysis (ICA) methods. The present article deals with the state of the art for SAR internal correlation analysis and proposes further extensions using elements of inference based on information theory applied to complex valued signals. The set of azimuth looks images is analyzed using mutual information measures and an equivalent channel capacity is derived. The localization of the "target" requires analysis in a small image window, thus resulting in imprecise estimation of the second order statistics of the signal. For a better precision, a Hausdorff measure is introduced. The method is applied to detect and characterize relevant objects in urban areas.

  8. An analytical solution for improved HIFU SAR estimation

    International Nuclear Information System (INIS)

    Dillon, C R; Vyas, U; Christensen, D A; Roemer, R B; Payne, A

    2012-01-01

    Accurate determination of the specific absorption rates (SARs) present during high intensity focused ultrasound (HIFU) experiments and treatments provides a solid physical basis for scientific comparison of results among HIFU studies and is necessary to validate and improve SAR predictive software, which will improve patient treatment planning, control and evaluation. This study develops and tests an analytical solution that significantly improves the accuracy of SAR values obtained from HIFU temperature data. SAR estimates are obtained by fitting the analytical temperature solution for a one-dimensional radial Gaussian heating pattern to the temperature versus time data following a step in applied power and evaluating the initial slope of the analytical solution. The analytical method is evaluated in multiple parametric simulations for which it consistently (except at high perfusions) yields maximum errors of less than 10% at the center of the focal zone compared with errors up to 90% and 55% for the commonly used linear method and an exponential method, respectively. For high perfusion, an extension of the analytical method estimates SAR with less than 10% error. The analytical method is validated experimentally by showing that the temperature elevations predicted using the analytical method's SAR values determined for the entire 3D focal region agree well with the experimental temperature elevations in a HIFU-heated tissue-mimicking phantom. (paper)

  9. 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…

  10. A patient with asymptomatic severe acute respiratory syndrome (SARS) and antigenemia from the 2003-2004 community outbreak of SARS in Guangzhou, China.

    Science.gov (United States)

    Che, Xiao-yan; Di, Biao; Zhao, Guo-ping; Wang, Ya-di; Qiu, Li-wen; Hao, Wei; Wang, Ming; Qin, Peng-zhe; Liu, Yu-fei; Chan, Kwok-hong; Cheng, Vincent C C; Yuen, Kwok-yung

    2006-07-01

    An asymptomatic case of severe acute respiratory syndrome (SARS) occurred early in 2004, during a community outbreak of SARS in Guangzhou, China. This was the first time that a case of asymptomatic SARS was noted in an individual with antigenemia and seroconversion. The asymptomatic case patient and the second index case patient with SARS in the 2003-2004 outbreak both worked in the same restaurant, where they served palm civets, which were found to carry SARS-associated coronaviruses. Epidemiological information and laboratory findings suggested that the findings for the patient with asymptomatic infection, together with the findings from previously reported serological analyses of handlers of wild animals and the 4 index case patients from the 2004 community outbreak, reflected a likely intermediate phase of animal-to-human transmission of infection, rather than a case of human-to-human transmission. This intermediate phase may be a critical stage for virus evolution and disease prevention.

  11. 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.

  12. Development and validation of a chronic copper biotic ligand model for Ceriodaphnia dubia

    International Nuclear Information System (INIS)

    Schwartz, Melissa L.; Vigneault, Bernard

    2007-01-01

    A biotic ligand model (BLM) to predict chronic Cu toxicity to Ceriodaphnia dubia was developed and tested. The effect of cationic competition, pH and natural organic matter complexation of Cu was examined to develop the model. There was no effect of cationic competition using increasing Ca and Na concentrations in our exposures. However, we did see a significant regression of decreasing toxicity (measured as the IC25; concentration at which there was a 25% inhibition of reproduction) as Mg concentration increased. However, taking into account the actual variability of the IC25 and since the relative increase in IC25 due to additional Mg was small (1.5-fold) Mg competition was not included in the model. Changes in pH had a significant effect on Cu IC25, which is consistent with proton competition as often suggested for acute BLMs. Finally, natural organic matter (NOM) was added to exposures resulting in significant decreases in toxicity. Therefore, our predictive model for chronic Cu toxicity to C. dubia includes the effect of pH and NOM complexation. The model was validated with Cu IC25 data generated in six natural surface waters collected from across Canada. Using WHAM VI, we calculated Cu speciation in each natural water and using our model, we generated 'predicted' IC25 data. We successfully predicted all Cu IC25 within a factor of 3 for the six waters used for validation

  13. AUTOMATIC COREGISTRATION FOR MULTIVIEW SAR IMAGES IN URBAN AREAS

    Directory of Open Access Journals (Sweden)

    Y. Xiang

    2017-09-01

    Full Text Available Due to the high resolution property and the side-looking mechanism of SAR sensors, complex buildings structures make the registration of SAR images in urban areas becomes very hard. In order to solve the problem, an automatic and robust coregistration approach for multiview high resolution SAR images is proposed in the paper, which consists of three main modules. First, both the reference image and the sensed image are segmented into two parts, urban areas and nonurban areas. Urban areas caused by double or multiple scattering in a SAR image have a tendency to show higher local mean and local variance values compared with general homogeneous regions due to the complex structural information. Based on this criterion, building areas are extracted. After obtaining the target regions, L-shape structures are detected using the SAR phase congruency model and Hough transform. The double bounce scatterings formed by wall and ground are shown as strong L- or T-shapes, which are usually taken as the most reliable indicator for building detection. According to the assumption that buildings are rectangular and flat models, planimetric buildings are delineated using the L-shapes, then the reconstructed target areas are obtained. For the orignal areas and the reconstructed target areas, the SAR-SIFT matching algorithm is implemented. Finally, correct corresponding points are extracted by the fast sample consensus (FSC and the transformation model is also derived. The experimental results on a pair of multiview TerraSAR images with 1-m resolution show that the proposed approach gives a robust and precise registration performance, compared with the orignal SAR-SIFT method.

  14. Monitoring of Three Case Studies of Creeping Landslides in Ecuador using L-band SAR Interferometry (InSAR)

    Science.gov (United States)

    Mayorga Torres, T. M.; Mohseni Aref, M.

    2015-12-01

    Tannia Mayorga Torres1,21 Universidad Central del Ecuador. Faculty of Geology, Mining, Oil, and Environment 2 Hubert H. Humphrey Fellowship 2015-16 IntroductionLandslides lead to human and economic losses across the country, mainly in the winter season. On the other hand, satellite radar data has cost-effective benefits due to open-source software and free availability of data. With the purpose of establishing an early warning system of landslide-related surface deformation, three case studies were designed in the Coast, Sierra (Andean), and Oriente (jungle) regions. The objective of this work was to assess the capability of L-band InSAR to get phase information. For the calculation of the interferograms in Repeat Orbit Interferometry PACkage, the displacement was detected as the error and was corrected. The coherence images (Figure 1) determined that L-band is suitable for InSAR processing. Under this frame, as a first approach, the stacking DInSAR technique [1] was applied in the case studies [2]; however, due to lush vegetation and steep topography, it is necessary to apply advanced InSAR techniques [3]. The purpose of the research is to determine a pattern of data acquisition and successful results to understand the spatial and temporal ground movements associated with landslides. The further work consists of establishing landslide inventories to combine phases of SAR images to generate maps of surface deformation in Tumba-San Francisco and Guarumales to compare the results with ground-based measurements to determine the maps' accuracy. References[1] Sandwell D., Price E. (1998). Phase gradient approach to stacking interferograms. Journal of Geophysical Research, Vol. 103, N. B12, pp. 30,183-30,204. [2] Mayorga T., Platzeck G. (2014). Using DInSAR as a tool to detect unstable terrain areas in an Andes region in Ecuador. NH3.5-Blue Poster B298, Vol. 16, EGU2014-16203. Austria. [3] Wasowski J., Bovenga F. (2014). Investigating landslides and unstable slopes with

  15. Applications of SAR Interferometry in Earth and Environmental Science Research.

    Science.gov (United States)

    Zhou, Xiaobing; Chang, Ni-Bin; Li, Shusun

    2009-01-01

    This paper provides a review of the progress in regard to the InSAR remote sensing technique and its applications in earth and environmental sciences, especially in the past decade. Basic principles, factors, limits, InSAR sensors, available software packages for the generation of InSAR interferograms were summarized to support future applications. Emphasis was placed on the applications of InSAR in seismology, volcanology, land subsidence/uplift, landslide, glaciology, hydrology, and forestry sciences. It ends with a discussion of future research directions.

  16. SARS Risk Perception, Knowledge, Precautions, and Information Sources, the Netherlands

    Science.gov (United States)

    Aro, Arja R.; Oenema, Anke; de Zwart, Onno; Richardus, Jan Hendrik; Bishop, George D.

    2004-01-01

    Severe acute respiratory syndrome (SARS)–related risk perceptions, knowledge, precautionary actions, and information sources were studied in the Netherlands during the 2003 SARS outbreak. Although respondents were highly aware of the SARS outbreak, the outbreak did not result in unnecessary precautionary actions or fears. PMID:15496256

  17. 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...

  18. Bats and SARS

    Centers for Disease Control (CDC) Podcasts

    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.

  19. 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.

  20. 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.

  1. Applications of SAR Interferometry in Earth and Environmental Science Research

    Science.gov (United States)

    Zhou, Xiaobing; Chang, Ni-Bin; Li, Shusun

    2009-01-01

    This paper provides a review of the progress in regard to the InSAR remote sensing technique and its applications in earth and environmental sciences, especially in the past decade. Basic principles, factors, limits, InSAR sensors, available software packages for the generation of InSAR interferograms were summarized to support future applications. Emphasis was placed on the applications of InSAR in seismology, volcanology, land subsidence/uplift, landslide, glaciology, hydrology, and forestry sciences. It ends with a discussion of future research directions. PMID:22573992

  2. Applications of SAR Interferometry in Earth and Environmental Science Research

    Directory of Open Access Journals (Sweden)

    Xiaobing Zhou

    2009-03-01

    Full Text Available This paper provides a review of the progress in regard to the InSAR remote sensing technique and its applications in earth and environmental sciences, especially in the past decade. Basic principles, factors, limits, InSAR sensors, available software packages for the generation of InSAR interferograms were summarized to support future applications. Emphasis was placed on the applications of InSAR in seismology, volcanology, land subsidence/uplift, landslide, glaciology, hydrology, and forestry sciences. It ends with a discussion of future research directions.

  3. 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....

  4. 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.

  5. New challenges for a SAR toolbox

    International Nuclear Information System (INIS)

    Loreaux, P.; Quin, G.

    2013-01-01

    High resolution multi-frequency synthetic aperture radar (SAR) imagery, available since early 2008, brings all weather capability and day/night operability in support of safeguards verification. Today, a combined approach of high resolution optical and radar imagery in monitoring exercise would enable looking at any area of interest on daily basis. One of the challenges is the co-registration of SAR images acquired with different acquisition mode and also with different optical images. We show in this paper the on-going research work to find a general co-register method and an automatic tool to detect changes. Before having an operational co-register tool, a method to find automatically tie points between SAR images acquired with different acquisition mode and with optical images has to be developed. Concerning an automatic change detection method we can conclude that the study of the Harmonic mean, Geometric mean and Arithmetic mean, enables several applications like change detection for SAR imagery. Thus, we developed the MAGMA (Method for Arithmetic and Geometric Means Analysis) change detection method. As shown in this paper, the MAGMA method improves the Maximum Likelihood techniques like GLRT, using Information-Theory concepts to detect changes between SAR amplitude images. The major improvement consists in a lower false detection rate, especially in low amplitude areas. The second improvement consists in a better location of the changes in clearly delimited areas, which enables precise interpretations. Results presented here reveal the potential of high resolution radar imagery for a baseline description of some sites, change detection based on repeat pass imagery acquisitions and site specific constraints in coherent change detection due to cover conditions. (A.C.)

  6. Detection of macroalgae blooms by complex SAR imagery

    International Nuclear Information System (INIS)

    Shen, Hui; Perrie, William; Liu, Qingrong; He, Yijun

    2014-01-01

    Highlights: • Complex SAR imagery enables better recognition of macroalgae patches. • Combination of different information in SAR matrix forms new index factors. • Proposed index factors contribute to unsupervised recognition of macroalgae. -- Abstract: Increased frequency and enhanced damage to the marine environment and to human society caused by green macroalgae blooms demand improved high-resolution early detection methods. Conventional satellite remote sensing methods via spectra radiometers do not work in cloud-covered areas, and therefore cannot meet these demands for operational applications. We present a methodology for green macroalgae bloom detection based on RADARSAT-2 synthetic aperture radar (SAR) images. Green macroalgae patches exhibit different polarimetric characteristics compared to the open ocean surface, in both the amplitude and phase domains of SAR-measured complex radar backscatter returns. In this study, new index factors are defined which have opposite signs in green macroalgae-covered areas, compared to the open water surface. These index factors enable unsupervised detection from SAR images, providing a high-resolution new tool for detection of green macroalgae blooms, which can potentially contribute to a better understanding of the mechanisms related to outbreaks of green macroalgae blooms in coastal areas throughout the world ocean

  7. Wavelet Filter Banks for Super-Resolution SAR Imaging

    Science.gov (United States)

    Sheybani, Ehsan O.; Deshpande, Manohar; Memarsadeghi, Nargess

    2011-01-01

    This paper discusses Innovative wavelet-based filter banks designed to enhance the analysis of super resolution Synthetic Aperture Radar (SAR) images using parametric spectral methods and signal classification algorithms, SAR finds applications In many of NASA's earth science fields such as deformation, ecosystem structure, and dynamics of Ice, snow and cold land processes, and surface water and ocean topography. Traditionally, standard methods such as Fast-Fourier Transform (FFT) and Inverse Fast-Fourier Transform (IFFT) have been used to extract Images from SAR radar data, Due to non-parametric features of these methods and their resolution limitations and observation time dependence, use of spectral estimation and signal pre- and post-processing techniques based on wavelets to process SAR radar data has been proposed. Multi-resolution wavelet transforms and advanced spectral estimation techniques have proven to offer efficient solutions to this problem.

  8. The economic impact of SARS in Beijing, China.

    Science.gov (United States)

    Beutels, Philippe; Jia, Na; Zhou, Qing-Yi; Smith, Richard; Cao, Wu-Chun; de Vlas, Sake J

    2009-11-01

    To document the impact of the severe acute respiratory syndrome (SARS) outbreak in Beijing on indicators of social and economic activity. Associations between time series of daily and monthly SARS cases and deaths and volume of public train, airplane and cargo transport, tourism, household consumption patterns and gross domestic product growth in Beijing were investigated using the cross-correlation function. Significant correlation coefficients were found for all indicators except wholesale accounts and expenditures on necessities, with the most significant correlations occurring with a delay of 1 day to 1 month. Especially leisure activities, local and international transport and tourism were affected by SARS particularly in May 2003. Much of this consumption was merely postponed; but irrecoverable losses to the tourist sector alone were estimated at about US$ 1.4 bn, or 300 times the cost of treatment for SARS cases in Beijing.

  9. [Effects of large bio-manipulation fish pen on community structure of crustacean zooplankton in Meiliang Bay of Taihu Lake].

    Science.gov (United States)

    Ke, Zhi-Xin; Xie, Ping; Guo, Long-Gen; Xu, Jun; Zhou, Qiong

    2012-08-01

    In 2005, a large bio-manipulation pen with the stock of silver carp and bighead carp was built to control the cyanobacterial bloom in Meiliang Bay of Taihu Lake. This paper investigated the seasonal variation of the community structure of crustacean zooplankton and the water quality within and outside the pen. There were no significant differences in the environmental parameters and phytoplankton biomass within and outside the pen. The species composition and seasonal dynamics of crustacean zooplankton within and outside the pen were similar, but the biomass of crustacean zooplankton was greatly suppressed by silver carp and bighead carp. The total crustacean zooplankton biomass and cladocerans biomass were significantly lower in the pen (P < 0.05). In general, silver carp and bighead carp exerted more pressure on cladoceran species than on copepod species. A distinct seasonal succession of crustacean zooplankton was observed in the Bay. Many crustacean species were only dominated in given seasons. Large-sized crustacean (mainly Daphnia sp. and Cyclops vicnus) dominated in winter and spring, while small-sized species (mainly Bosmina sp., Ceriodaphnia cornuta, and Limnoithona sinensis) dominated in summer and autumn. Canonical correspondence analysis showed that water transparency, temperature, and phytoplankton biomass were the most important factors affecting the seasonal succession of the crustacean.

  10. 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

  11. 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.

  12. Prototype Theory Based Feature Representation for PolSAR Images

    OpenAIRE

    Huang Xiaojing; Yang Xiangli; Huang Pingping; Yang Wen

    2016-01-01

    This study presents a new feature representation approach for Polarimetric Synthetic Aperture Radar (PolSAR) image based on prototype theory. First, multiple prototype sets are generated using prototype theory. Then, regularized logistic regression is used to predict similarities between a test sample and each prototype set. Finally, the PolSAR image feature representation is obtained by ensemble projection. Experimental results of an unsupervised classification of PolSAR images show that our...

  13. One carbon metabolism in SAR11 pelagic marine bacteria.

    Directory of Open Access Journals (Sweden)

    Jing Sun

    Full Text Available The SAR11 Alphaproteobacteria are the most abundant heterotrophs in the oceans and are believed to play a major role in mineralizing marine dissolved organic carbon. Their genomes are among the smallest known for free-living heterotrophic cells, raising questions about how they successfully utilize complex organic matter with a limited metabolic repertoire. Here we show that conserved genes in SAR11 subgroup Ia (Candidatus Pelagibacter ubique genomes encode pathways for the oxidation of a variety of one-carbon compounds and methyl functional groups from methylated compounds. These pathways were predicted to produce energy by tetrahydrofolate (THF-mediated oxidation, but not to support the net assimilation of biomass from C1 compounds. Measurements of cellular ATP content and the oxidation of (14C-labeled compounds to (14CO(2 indicated that methanol, formaldehyde, methylamine, and methyl groups from glycine betaine (GBT, trimethylamine (TMA, trimethylamine N-oxide (TMAO, and dimethylsulfoniopropionate (DMSP were oxidized by axenic cultures of the SAR11 strain Ca. P. ubique HTCC1062. Analyses of metagenomic data showed that genes for C1 metabolism occur at a high frequency in natural SAR11 populations. In short term incubations, natural communities of Sargasso Sea microbial plankton expressed a potential for the oxidation of (14C-labeled formate, formaldehyde, methanol and TMAO that was similar to cultured SAR11 cells and, like cultured SAR11 cells, incorporated a much larger percentage of pyruvate and glucose (27-35% than of C1 compounds (2-6% into biomass. Collectively, these genomic, cellular and environmental data show a surprising capacity for demethylation and C1 oxidation in SAR11 cultures and in natural microbial communities dominated by SAR11, and support the conclusion that C1 oxidation might be a significant conduit by which dissolved organic carbon is recycled to CO(2 in the upper ocean.

  14. 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.

  15. Comparison of SAR calculation algorithms for the finite-difference time-domain method

    International Nuclear Information System (INIS)

    Laakso, Ilkka; Uusitupa, Tero; Ilvonen, Sami

    2010-01-01

    Finite-difference time-domain (FDTD) simulations of specific-absorption rate (SAR) have several uncertainty factors. For example, significantly varying SAR values may result from the use of different algorithms for determining the SAR from the FDTD electric field. The objective of this paper is to rigorously study the divergence of SAR values due to different SAR calculation algorithms and to examine if some SAR calculation algorithm should be preferred over others. For this purpose, numerical FDTD results are compared to analytical solutions in a one-dimensional layered model and a three-dimensional spherical object. Additionally, the implications of SAR calculation algorithms for dosimetry of anatomically realistic whole-body models are studied. The results show that the trapezium algorithm-based on the trapezium integration rule-is always conservative compared to the analytic solution, making it a good choice for worst-case exposure assessment. In contrast, the mid-ordinate algorithm-named after the mid-ordinate integration rule-usually underestimates the analytic SAR. The linear algorithm-which is approximately a weighted average of the two-seems to be the most accurate choice overall, typically giving the best fit with the shape of the analytic SAR distribution. For anatomically realistic models, the whole-body SAR difference between different algorithms is relatively independent of the used body model, incident direction and polarization of the plane wave. The main factors affecting the difference are cell size and frequency. The choice of the SAR calculation algorithm is an important simulation parameter in high-frequency FDTD SAR calculations, and it should be explained to allow intercomparison of the results between different studies. (note)

  16. Evidence of rock slope breathing using ground-based InSAR

    Science.gov (United States)

    Rouyet, Line; Kristensen, Lene; Derron, Marc-Henri; Michoud, Clément; Blikra, Lars Harald; Jaboyedoff, Michel; Lauknes, Tom Rune

    2017-07-01

    Ground-Based Interferometric Synthetic Aperture Radar (GB-InSAR) campaigns were performed in summer 2011 and 2012 in the Romsdalen valley (Møre & Romsdal county, western Norway) in order to assess displacements on Mannen/Børa rock slope. Located 1 km northwest, a second GB-InSAR system continuously monitors the large Mannen rockslide. The availability of two GB-InSAR positions creates a wide coverage of the rock slope, including a slight dataset overlap valuable for validation. A phenomenon of rock slope breathing is detected in a remote and hard-to-access area in mid-slope. Millimetric upward displacements are recorded in August 2011. Analysis of 2012 GB-InSAR campaign, combined with the large dataset from the continuous station, shows that the slope is affected by inflation/deflation phenomenon between 5 and 10 mm along the line-of-sight. The pattern is not homogenous in time and inversions of movement have a seasonal recurrence. These seasonal changes are confirmed by satellite InSAR observations and can possibly be caused by hydrogeological variations. In addition, combination of GB-InSAR results, in situ measurements and satellite InSAR analyses contributes to a better overview of movement distribution over the whole area.

  17. Influence of glyphosate and its formulation (Roundup[reg]) on the toxicity and bioavailability of metals to Ceriodaphnia dubia

    Energy Technology Data Exchange (ETDEWEB)

    Tsui, Martin T.K. [Department of Biology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (China); Department of Biology, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong (China); Wang Wenxiong [Department of Biology, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong (China); Chu, L.M. [Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (China)]. E-mail: leemanchu@cuhk.edu.hk

    2005-11-15

    This study examined the toxicological interaction between glyphosate (or its formulation, Roundup[reg]) and several heavy metals to a freshwater cladoceran, Ceriodaphnia dubia. We demonstrated that all binary combinations of Roundup[reg] and metals (Cd, Cu, Cr, Ni, Pb, Se and Zn) exhibited 'less than additive' mixture toxicity, with 48-h LC50 toxic unit>1. Addition of glyphosate alone could significantly reduce the acute toxicity of Ag, Cd, Cr, Cu, Ni, Pb and Zn (but not Hg and Se). The ratio between glyphosate and metal ions was important in determining the mitigation of metal toxicity by glyphosate. A bioaccumulation study showed that in the presence of glyphosate the uptake of some metals (e.g. Ag) was halted but that of others (e.g. Hg) was increased significantly. Therefore, our study strongly suggests that glyphosate and its commercial formulations can control the toxicity as well as the bioavailability of heavy metals in aquatic ecosystems where both groups of chemicals can co-occur. - Glyphosate can control the toxicity and bioavailability of many heavy metals in the aquatic environment.

  18. Influence of glyphosate and its formulation (Roundup[reg]) on the toxicity and bioavailability of metals to Ceriodaphnia dubia

    International Nuclear Information System (INIS)

    Tsui, Martin T.K.; Wang Wenxiong; Chu, L.M.

    2005-01-01

    This study examined the toxicological interaction between glyphosate (or its formulation, Roundup[reg]) and several heavy metals to a freshwater cladoceran, Ceriodaphnia dubia. We demonstrated that all binary combinations of Roundup[reg] and metals (Cd, Cu, Cr, Ni, Pb, Se and Zn) exhibited 'less than additive' mixture toxicity, with 48-h LC50 toxic unit>1. Addition of glyphosate alone could significantly reduce the acute toxicity of Ag, Cd, Cr, Cu, Ni, Pb and Zn (but not Hg and Se). The ratio between glyphosate and metal ions was important in determining the mitigation of metal toxicity by glyphosate. A bioaccumulation study showed that in the presence of glyphosate the uptake of some metals (e.g. Ag) was halted but that of others (e.g. Hg) was increased significantly. Therefore, our study strongly suggests that glyphosate and its commercial formulations can control the toxicity as well as the bioavailability of heavy metals in aquatic ecosystems where both groups of chemicals can co-occur. - Glyphosate can control the toxicity and bioavailability of many heavy metals in the aquatic environment

  19. Global Rapid Flood Mapping System with Spaceborne SAR Data

    Science.gov (United States)

    Yun, S. H.; Owen, S. E.; Hua, H.; Agram, P. S.; Fattahi, H.; Liang, C.; Manipon, G.; Fielding, E. J.; Rosen, P. A.; Webb, F.; Simons, M.

    2017-12-01

    As part of the Advanced Rapid Imaging and Analysis (ARIA) project for Natural Hazards, at NASA's Jet Propulsion Laboratory and California Institute of Technology, we have developed an automated system that produces derived products for flood extent map generation using spaceborne SAR data. The system takes user's input of area of interest polygons and time window for SAR data search (pre- and post-event). Then the system automatically searches and downloads SAR data, processes them to produce coregistered SAR image pairs, and generates log amplitude ratio images from each pair. Currently the system is automated to support SAR data from the European Space Agency's Sentinel-1A/B satellites. We have used the system to produce flood extent maps from Sentinel-1 SAR data for the May 2017 Sri Lanka floods, which killed more than 200 people and displaced about 600,000 people. Our flood extent maps were delivered to the Red Cross to support response efforts. Earlier we also responded to the historic August 2016 Louisiana floods in the United States, which claimed 13 people's lives and caused over $10 billion property damage. For this event, we made synchronized observations from space, air, and ground in close collaboration with USGS and NOAA. The USGS field crews acquired ground observation data, and NOAA acquired high-resolution airborne optical imagery within the time window of +/-2 hours of the SAR data acquisition by JAXA's ALOS-2 satellite. The USGS coordinates of flood water boundaries were used to calibrate our flood extent map derived from the ALOS-2 SAR data, and the map was delivered to FEMA for estimating the number of households affected. Based on the lessons learned from this response effort, we customized the ARIA system automation for rapid flood mapping and developed a mobile friendly web app that can easily be used in the field for data collection. Rapid automatic generation of SAR-based global flood maps calibrated with independent observations from

  20. Analysis of Spatiotemporal Characteristics of Pandemic SARS Spread in Mainland China.

    Science.gov (United States)

    Cao, Chunxiang; Chen, Wei; Zheng, Sheng; Zhao, Jian; Wang, Jinfeng; Cao, Wuchun

    2016-01-01

    Severe acute respiratory syndrome (SARS) is one of the most severe emerging infectious diseases of the 21st century so far. SARS caused a pandemic that spread throughout mainland China for 7 months, infecting 5318 persons in 194 administrative regions. Using detailed mainland China epidemiological data, we study spatiotemporal aspects of this person-to-person contagious disease and simulate its spatiotemporal transmission dynamics via the Bayesian Maximum Entropy (BME) method. The BME reveals that SARS outbreaks show autocorrelation within certain spatial and temporal distances. We use BME to fit a theoretical covariance model that has a sine hole spatial component and exponential temporal component and obtain the weights of geographical and temporal autocorrelation factors. Using the covariance model, SARS dynamics were estimated and simulated under the most probable conditions. Our study suggests that SARS transmission varies in its epidemiological characteristics and SARS outbreak distributions exhibit palpable clusters on both spatial and temporal scales. In addition, the BME modelling demonstrates that SARS transmission features are affected by spatial heterogeneity, so we analyze potential causes. This may benefit epidemiological control of pandemic infectious diseases.

  1. 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

    The 5300 km2 pristine Sian Ka'an wetland in Mexico is fed entirely by groundwater from the karst aquifer of the Yucatan Peninsula. The area is undeveloped and hence difficult to access. The inflow through underground rivers and karst structures is hard to observe resulting in difficulties......-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...... maps with 24 to 48 day intervals covering the time span of October 2006 to March 2008. The dataset has a high spatial resolution of ca. 20 to 60 m. Sian Ka'an consists of a mosaic of freshwater sloughs, canals, floodplains and brackish tidally-influenced areas. Throughout most of the year, water level...

  2. Methodology of dose calculation for the SRS SAR

    International Nuclear Information System (INIS)

    Price, J.B.

    1991-07-01

    The Savannah River Site (SRS) Safety Analysis Report (SAR) covering K reactor operation assesses a spectrum of design basis accidents. The assessment includes estimation of the dose consequences from the analyzed accidents. This report discusses the methodology used to perform the dose analysis reported in the SAR and also includes the quantified doses. Doses resulting from postulated design basis reactor accidents in Chapter 15 of the SAR are discussed, as well as an accident in which three percent of the fuel melts. Doses are reported for both atmospheric and aqueous releases. The methodology used to calculate doses from these accidents as reported in the SAR is consistent with NRC guidelines and industry standards. The doses from the design basis accidents for the SRS reactors are below the limits set for commercial reactors by the NRC and also meet industry criteria. A summary of doses for various postulated accidents is provided

  3. Empirical wind retrieval model based on SAR spectrum measurements

    Science.gov (United States)

    Panfilova, Maria; Karaev, Vladimir; Balandina, Galina; Kanevsky, Mikhail; Portabella, Marcos; Stoffelen, Ad

    The present paper considers polarimetric SAR wind vector applications. Remote-sensing measurements of the near-surface wind over the ocean are of great importance for the understanding of atmosphere-ocean interaction. In recent years investigations for wind vector retrieval using Synthetic Aperture Radar (SAR) data have been performed. In contrast with scatterometers, a SAR has a finer spatial resolution that makes it a more suitable microwave instrument to explore wind conditions in the marginal ice zones, coastal regions and lakes. The wind speed retrieval procedure from scatterometer data matches the measured radar backscattering signal with the geophysical model function (GMF). The GMF determines the radar cross section dependence on the wind speed and direction with respect to the azimuthal angle of the radar beam. Scatterometers provide information on wind speed and direction simultaneously due to the fact that each wind vector cell (WVC) is observed at several azimuth angles. However, SAR is not designed to be used as a high resolution scatterometer. In this case, each WVC is observed at only one single azimuth angle. That is why for wind vector determination additional information such as wind streak orientation over the sea surface is required. It is shown that the wind vector can be obtained using polarimetric SAR without additional information. The main idea is to analyze the spectrum of a homogeneous SAR image area instead of the backscattering normalized radar cross section. Preliminary numerical simulations revealed that SAR image spectral maxima positions depend on the wind vector. Thus the following method for wind speed retrieval is proposed. In the first stage of the algorithm, the SAR spectrum maxima are determined. This procedure is carried out to estimate the wind speed and direction with ambiguities separated by 180 degrees due to the SAR spectrum symmetry. The second stage of the algorithm allows us to select the correct wind direction

  4. Demonstrator for Automatic Target Classification in SAR Imagery

    NARCIS (Netherlands)

    Wit, J.J.M. de; Broek, A.C. van den; Dekker, R.J.

    2006-01-01

    Due to the increasing use of unmanned aerial vehicles (UAV) for reconnaissance, surveillance, and target acquisition applications, the interest in synthetic aperture radar (SAR) systems is growing. In order to facilitate the processing of the enormous amount of SAR data on the ground, automatic

  5. 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.

  6. Phase correction and error estimation in InSAR time series analysis

    Science.gov (United States)

    Zhang, Y.; Fattahi, H.; Amelung, F.

    2017-12-01

    During the last decade several InSAR time series approaches have been developed in response to the non-idea acquisition strategy of SAR satellites, such as large spatial and temporal baseline with non-regular acquisitions. The small baseline tubes and regular acquisitions of new SAR satellites such as Sentinel-1 allows us to form fully connected networks of interferograms and simplifies the time series analysis into a weighted least square inversion of an over-determined system. Such robust inversion allows us to focus more on the understanding of different components in InSAR time-series and its uncertainties. We present an open-source python-based package for InSAR time series analysis, called PySAR (https://yunjunz.github.io/PySAR/), with unique functionalities for obtaining unbiased ground displacement time-series, geometrical and atmospheric correction of InSAR data and quantifying the InSAR uncertainty. Our implemented strategy contains several features including: 1) improved spatial coverage using coherence-based network of interferograms, 2) unwrapping error correction using phase closure or bridging, 3) tropospheric delay correction using weather models and empirical approaches, 4) DEM error correction, 5) optimal selection of reference date and automatic outlier detection, 6) InSAR uncertainty due to the residual tropospheric delay, decorrelation and residual DEM error, and 7) variance-covariance matrix of final products for geodetic inversion. We demonstrate the performance using SAR datasets acquired by Cosmo-Skymed and TerraSAR-X, Sentinel-1 and ALOS/ALOS-2, with application on the highly non-linear volcanic deformation in Japan and Ecuador (figure 1). Our result shows precursory deformation before the 2015 eruptions of Cotopaxi volcano, with a maximum uplift of 3.4 cm on the western flank (fig. 1b), with a standard deviation of 0.9 cm (fig. 1a), supporting the finding by Morales-Rivera et al. (2017, GRL); and a post-eruptive subsidence on the same

  7. Fast Superpixel Segmentation Algorithm for PolSAR Images

    Directory of Open Access Journals (Sweden)

    Zhang Yue

    2017-10-01

    Full Text Available As a pre-processing technique, superpixel segmentation algorithms should be of high computational efficiency, accurate boundary adherence and regular shape in homogeneous regions. A fast superpixel segmentation algorithm based on Iterative Edge Refinement (IER has shown to be applicable on optical images. However, it is difficult to obtain the ideal results when IER is applied directly to PolSAR images due to the speckle noise and small or slim regions in PolSAR images. To address these problems, in this study, the unstable pixel set is initialized as all the pixels in the PolSAR image instead of the initial grid edge pixels. In the local relabeling of the unstable pixels, the fast revised Wishart distance is utilized instead of the Euclidean distance in CIELAB color space. Then, a post-processing procedure based on dissimilarity measure is empolyed to remove isolated small superpixels as well as to retain the strong point targets. Finally, extensive experiments based on a simulated image and a real-world PolSAR image from Airborne Synthetic Aperture Radar (AirSAR are conducted, showing that the proposed algorithm, compared with three state-of-the-art methods, performs better in terms of several commonly used evaluation criteria with high computational efficiency, accurate boundary adherence, and homogeneous regularity.

  8. 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.

  9. 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...... will contain more than 600,000 discrete organic structures and new, more precise predictions for all endpoints, derived by consensus algorithms from a number of state-of-the-art individual predictions. Copyright © 2013 Published by Elsevier Ireland Ltd....

  10. First Image Products from EcoSAR - Osa Peninsula, Costa Rica

    Science.gov (United States)

    Osmanoglu, Batuhan; Lee, SeungKuk; Rincon, Rafael; Fatuyinbo, Lola; Bollian, Tobias; Ranson, Jon

    2016-01-01

    Designed especially for forest ecosystem studies, EcoSAR employs state-of-the-art digital beamforming technology to generate wide-swath, high-resolution imagery. EcoSARs dual antenna single-pass imaging capability eliminates temporal decorrelation from polarimetric and interferometric analysis, increasing the signal strength and simplifying models used to invert forest structure parameters. Antennae are physically separated by 25 meters providing single pass interferometry. In this mode the radar is most sensitive to topography. With 32 active transmit and receive channels, EcoSARs digital beamforming is an order of magnitude more versatile than the digital beamforming employed on the upcoming NISAR mission. EcoSARs long wavelength (P-band, 435 MHz, 69 cm) measurements can be used to simulate data products for ESAs future BIOMASS mission, allowing scientists to develop algorithms before the launch of the satellite. EcoSAR can also be deployed to collect much needed data where BIOMASS satellite wont be allowed to collect data (North America, Europe and Arctic), filling in the gaps to keep a watchful eye on the global carbon cycle. EcoSAR can play a vital role in monitoring, reporting and verification schemes of internationals programs such as UN-REDD (United Nations Reducing Emissions from Deforestation and Degradation) benefiting global society. EcoSAR was developed and flown with support from NASA Earth Sciences Technology Offices Instrument Incubator Program.

  11. Research on the method of extracting DEM based on GBInSAR

    Science.gov (United States)

    Yue, Jianping; Yue, Shun; Qiu, Zhiwei; Wang, Xueqin; Guo, Leping

    2016-05-01

    Precise topographical information has a very important role in geology, hydrology, natural resources survey and deformation monitoring. The extracting DEM technology based on synthetic aperture radar interferometry (InSAR) obtains the three-dimensional elevation of the target area through the phase information of the radar image data. The technology has large-scale, high-precision, all-weather features. By changing track in the location of the ground radar system up and down, it can form spatial baseline. Then we can achieve the DEM of the target area by acquiring image data from different angles. Three-dimensional laser scanning technology can quickly, efficiently and accurately obtain DEM of target area, which can verify the accuracy of DEM extracted by GBInSAR. But research on GBInSAR in extracting DEM of the target area is a little. For lack of theory and lower accuracy problems in extracting DEM based on GBInSAR now, this article conducted research and analysis on its principle deeply. The article extracted the DEM of the target area, combined with GBInSAR data. Then it compared the DEM obtained by GBInSAR with the DEM obtained by three-dimensional laser scan data and made statistical analysis and normal distribution test. The results showed the DEM obtained by GBInSAR was broadly consistent with the DEM obtained by three-dimensional laser scanning. And its accuracy is high. The difference of both DEM approximately obeys normal distribution. It indicated that extracting the DEM of target area based on GBInSAR is feasible and provided the foundation for the promotion and application of GBInSAR.

  12. The effect of severe acute respiratory syndrome (SARS) on emergency airway management.

    Science.gov (United States)

    Wong, Evelyn; Ho, Khoy Kheng

    2006-07-01

    From early March 2003 to late May 2003, severe acute respiratory syndrome (SARS) was detected in Singapore. The increase in workload and new infection control procedures were thought to affect resuscitation and airway management. Our aim was to study the effects of wearing of personal protective equipment (PPE) and powered air-purifying respirator (PAPR) and the restriction in the number of resuscitation personnel on airway management during the SARS crisis. Data was collected prospectively through an ongoing emergency airway registry. The data was divided into three periods: (1) before PPE was instituted from 1 November 2002 to 31 March 2003; (2) during SARS (when PPE use was mandatory) from 1 April to 31 July 2003; (3) post-SARs (when PPE use was non-mandatory but encouraged) from 1 August to 31 March 2004. There was no change in patient demographics during the three periods. There were significant increases in the proportion of resuscitation cases and airway interventions during the SARS period compared to the pre-SARS period. The resident medical officer intubation rate decreased from 45.1% pre-SARS to 35.2% during SARS and 17.7% post-SARS. The complication rates were 10.5%, 9.9% and 9.4% in periods 1-3, respectively. Restriction in the number of healthcare staff attending to each patient may have influenced the department's decision to allow only the most confident or experienced personnel to manage the airway. The exposure of junior medical officers in emergency airway management during SARS and the immediate post-SARS period was decreased. This trend should be monitored further and intervention may be necessary should it continue to decline.

  13. Synthetic aperture design for increased SAR image rate

    Science.gov (United States)

    Bielek, Timothy P [Albuquerque, NM; Thompson, Douglas G [Albuqerque, NM; Walker, Bruce C [Albuquerque, NM

    2009-03-03

    High resolution SAR images of a target scene at near video rates can be produced by using overlapped, but nevertheless, full-size synthetic apertures. The SAR images, which respectively correspond to the apertures, can be analyzed in sequence to permit detection of movement in the target scene.

  14. 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...

  15. SEGMENTATION OF POLARIMETRIC SAR IMAGES USIG WAVELET TRANSFORMATION AND TEXTURE FEATURES

    Directory of Open Access Journals (Sweden)

    A. Rezaeian

    2015-12-01

    Full Text Available Polarimetric Synthetic Aperture Radar (PolSAR sensors can collect useful observations from earth’s surfaces and phenomena for various remote sensing applications, such as land cover mapping, change and target detection. These data can be acquired without the limitations of weather conditions, sun illumination and dust particles. As result, SAR images, and in particular Polarimetric SAR (PolSAR are powerful tools for various environmental applications. Unlike the optical images, SAR images suffer from the unavoidable speckle, which causes the segmentation of this data difficult. In this paper, we use the wavelet transformation for segmentation of PolSAR images. Our proposed method is based on the multi-resolution analysis of texture features is based on wavelet transformation. Here, we use the information of gray level value and the information of texture. First, we produce coherency or covariance matrices and then generate span image from them. In the next step of proposed method is texture feature extraction from sub-bands is generated from discrete wavelet transform (DWT. Finally, PolSAR image are segmented using clustering methods as fuzzy c-means (FCM and k-means clustering. We have applied the proposed methodology to full polarimetric SAR images acquired by the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR L-band system, during July, in 2012 over an agricultural area in Winnipeg, Canada.

  16. Segmentation of Polarimetric SAR Images Usig Wavelet Transformation and Texture Features

    Science.gov (United States)

    Rezaeian, A.; Homayouni, S.; Safari, A.

    2015-12-01

    Polarimetric Synthetic Aperture Radar (PolSAR) sensors can collect useful observations from earth's surfaces and phenomena for various remote sensing applications, such as land cover mapping, change and target detection. These data can be acquired without the limitations of weather conditions, sun illumination and dust particles. As result, SAR images, and in particular Polarimetric SAR (PolSAR) are powerful tools for various environmental applications. Unlike the optical images, SAR images suffer from the unavoidable speckle, which causes the segmentation of this data difficult. In this paper, we use the wavelet transformation for segmentation of PolSAR images. Our proposed method is based on the multi-resolution analysis of texture features is based on wavelet transformation. Here, we use the information of gray level value and the information of texture. First, we produce coherency or covariance matrices and then generate span image from them. In the next step of proposed method is texture feature extraction from sub-bands is generated from discrete wavelet transform (DWT). Finally, PolSAR image are segmented using clustering methods as fuzzy c-means (FCM) and k-means clustering. We have applied the proposed methodology to full polarimetric SAR images acquired by the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) L-band system, during July, in 2012 over an agricultural area in Winnipeg, Canada.

  17. Excretion and detection of SARS coronavirus and its nucleic acid from digestive system

    Science.gov (United States)

    Wang, Xin-Wei; Li, Jin-Song; Guo, Ting-Kai; Zhen, Bei; Kong, Qing-Xin; Yi, Bin; Li, Zhong; Song, Nong; Jin, Min; Wu, Xiao-Ming; Xiao, Wen-Jun; Zhu, Xiu-Mei; Gu, Chang-Qing; Yin, Jing; Wei, Wei; Yao, Wei; Liu, Chao; Li, Jian-Feng; Ou, Guo-Rong; Wang, Min-Nian; Fang, Tong-Yu; Wang, Gui-Jie; Qiu, Yao-Hui; Wu, Huai-Huan; Chao, Fu-Huan; Li, Jun-Wen

    2005-01-01

    AIM: To study whether severe acute respiratory syndrome coronavirus (SARS-CoV) could be excreted from digestive system. METHODS: Cell culture and semi-nested RT-PCR were used to detect SARS-CoV and its RNA from 21 stool and urine samples, and a kind of electropositive filter media particles was used to concentrate the virus in 10 sewage samples from two hospitals receiving SARS patients in Beijing in China. RESULTS: It was demonstrated that there was no live SARS-CoV in all samples collected, but the RNA of SARS-CoV could be detected in seven stool samples from SARS patients with any one of the symptoms of fever, malaise, cough, or dyspnea, in 10 sewage samples before disinfection and 3 samples after disinfection from the two hospitals. The RNA could not be detected in urine and stool samples from patients recovered from SARS. CONCLUSION: Nucleic acid of SARS-CoV can be excreted through the stool of patients into sewage system, and the possibility of SARS-CoV transmitting through digestive system cannot be excluded. PMID:16038039

  18. PSInSAR technology and its use for monitoring of the Earth's surface deformation; Technologia PSInSAR a jej vyuzitie na monitorovanie deformacii zemskeho povrchu

    Energy Technology Data Exchange (ETDEWEB)

    Batorova, K [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Katedra inzinierskej geologie, 84215 Bratislava (Slovakia)

    2012-04-25

    Method of permanent reflex points (PSInSAR) allows to monitor the time evolution of deformations of the Earth's surface with a millimeter precision. For deformation size determination there are used the maps of movement speed or time delay of line set of data that are obtained by evaluating of SAR images. SAR files must be processed using the basic mathematical calculation presented in the work, with an emphasis on the parameters used in geology. Extensive processing of multiple SAR imagery showed that they can be used during monitoring of the field with an accurate identification of the objects on the Earth's surface, which provide a stable reflection of radar rays transmitted from the satellite. These objects are known as permanent reflection points (PS). PS can be geo-referenced, allowing accurate determination of the movement size of the Earth's surface deformation. In this paper an example of using of PSInSAR technology for monitoring of slope movements on the territory of Slovakia is presented. (authors)

  19. Analysis of Spatiotemporal Characteristics of Pandemic SARS Spread in Mainland China

    Directory of Open Access Journals (Sweden)

    Chunxiang Cao

    2016-01-01

    Full Text Available Severe acute respiratory syndrome (SARS is one of the most severe emerging infectious diseases of the 21st century so far. SARS caused a pandemic that spread throughout mainland China for 7 months, infecting 5318 persons in 194 administrative regions. Using detailed mainland China epidemiological data, we study spatiotemporal aspects of this person-to-person contagious disease and simulate its spatiotemporal transmission dynamics via the Bayesian Maximum Entropy (BME method. The BME reveals that SARS outbreaks show autocorrelation within certain spatial and temporal distances. We use BME to fit a theoretical covariance model that has a sine hole spatial component and exponential temporal component and obtain the weights of geographical and temporal autocorrelation factors. Using the covariance model, SARS dynamics were estimated and simulated under the most probable conditions. Our study suggests that SARS transmission varies in its epidemiological characteristics and SARS outbreak distributions exhibit palpable clusters on both spatial and temporal scales. In addition, the BME modelling demonstrates that SARS transmission features are affected by spatial heterogeneity, so we analyze potential causes. This may benefit epidemiological control of pandemic infectious diseases.

  20. Chinese HJ-1C SAR And Its Wind Mapping Capability

    Science.gov (United States)

    Huang, Weigen; Chen, Fengfeng; Yang, Jingsong; Fu, Bin; Chen, Peng; Zhang, Chan

    2010-04-01

    Chinese Huan Jing (HJ)-1C synthetic aperture radar (SAR) satellite has been planed to be launched in 2010. HJ-1C satellite will fly in a sun-synchronous polar orbit of 500-km altitude. SAR will be the only sensor on board the satellite. It operates in S band with VV polarization. Its image mode has the incidence angles 25°and 47°at the near and far sides of the swath respectively. There are two selectable SAR modes of operation, which are fine resolution beams and standard beams respectively. The sea surface wind mapping capability of the SAR has been examined using M4S radar imaging model developed by Romeiser. The model is based on Bragg scattering theory in a composite surface model expansion. It accounts for contributions of the full ocean wave spectrum to the radar backscatter from ocean surface. The model reproduces absolute normalized radar cross section (NRCS) values for wide ranges of wind speeds. The model results of HJ-1C SAR have been compared with the model results of Envisat ASAR. It shows that HJ-1C SAR is as good as Envisat ASAR at sea surface wind mapping.

  1. ANALYSIS OF MULTIPATH PIXELS IN SAR IMAGES

    Directory of Open Access Journals (Sweden)

    J. W. Zhao

    2016-06-01

    Full Text Available As the received radar signal is the sum of signal contributions overlaid in one single pixel regardless of the travel path, the multipath effect should be seriously tackled as the multiple bounce returns are added to direct scatter echoes which leads to ghost scatters. Most of the existing solution towards the multipath is to recover the signal propagation path. To facilitate the signal propagation simulation process, plenty of aspects such as sensor parameters, the geometry of the objects (shape, location, orientation, mutual position between adjacent buildings and the physical parameters of the surface (roughness, correlation length, permittivitywhich determine the strength of radar signal backscattered to the SAR sensor should be given in previous. However, it's not practical to obtain the highly detailed object model in unfamiliar area by field survey as it's a laborious work and time-consuming. In this paper, SAR imaging simulation based on RaySAR is conducted at first aiming at basic understanding of multipath effects and for further comparison. Besides of the pre-imaging simulation, the product of the after-imaging, which refers to radar images is also taken into consideration. Both Cosmo-SkyMed ascending and descending SAR images of Lupu Bridge in Shanghai are used for the experiment. As a result, the reflectivity map and signal distribution map of different bounce level are simulated and validated by 3D real model. The statistic indexes such as the phase stability, mean amplitude, amplitude dispersion, coherence and mean-sigma ratio in case of layover are analyzed with combination of the RaySAR output.

  2. Early appearance of SARS on chest CT scan

    International Nuclear Information System (INIS)

    Cheng Xiaoguang; Feng Suchen; Xia Guoguang; Zhao Tao; Gu Xiang; Qu Hui

    2003-01-01

    Objective: To evaluate the early appearance of SARS on chest CT scan and its role in the early diagnosis. Methods: Forty cases of SARS in keeping with the criteria of the Ministry of Health had chest CT scans within 7 days of onset of symptoms, and CR chest X-ray films were available as well. These chest X-rays and CT images were retrospectively reviewed to determine if there were any abnormalities on the images. The lesions on the chest CT images were then further analyzed in terms of the number, location, size, and density. Results: Positive abnormalities on chest CT scans were revealed in all 40 SARS cases. Positive findings on CR chest films were showed in only 25 cases, equivocal in 6, and normal in 9 cases. The main abnormalities seen on CT and X-rays were pulmonary infiltrations varied markedly in severity. 70 % cases had 1 or 2 lesions on chest CT scan, 30 % cases had 3 or more lesions. The lesions seen on chest CT scan tended to be ground-glass opacification, sometimes with consolidation which was very faint and inhomogeneous, easily missed on chest X-rays. Typically the lesions were located in the periphery of the lung, or both central and peripheral lung, but very rare in a pure central location. They were commonly in the shape of patch or ball. Conclusions: Chest CT scan is much more sensitive in detecting the lesions of the lung in SARS. The early appearance of SARS on chest CT scan is characteristic but non-specific, indicating that chest CT scan plays a very important role in the early diagnosis and differential diagnosis of SARS

  3. Influence of exposure time on the distribution of cadmium within the cladoceran Ceriodaphnia dubia

    International Nuclear Information System (INIS)

    Munger, C.; Hare, L.; Craig, A.; Charest, P.-M.

    1998-01-01

    The internal distribution of a trace metal can be useful in determining in which body organ toxic effects are most likely to occur and the animal function most likely to be affected. In addition, because a metal's distribution within an organism is likely to influence the rate and efficiency with which it is transferred to a higher trophic level, laboratory measurements of trophic transfer could be influenced by exposure duration. We compared the internal distribution of cadmium (Cd) in a cladoceran crustacean (Ceriodaphnia dubia) destined as food for a predatory insect (Chaoborus) after either a 1 day or a lifetime of exposure of prey to the trace metal. Prey were exposed to 112+109 Cd in both water (10 nM) and their food (algae), as might occur in nature. The internal distribution of 109 Cd in the cladoceran was determined by whole-animal autoradiography. Both the amount and the tissue distribution of Cd in prey were the same after the short and the long term exposures, suggesting that metal accumulation parameters measured after short-term metal exposures can be valid for this animal. Cadmium was mainly accumulated in diverticula of the anterior midgut, a region reported to be responsible for nutrient absorption. We hypothesize that Cd is accumulated in the diverticula because of their purported role as sites of calcium uptake. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  4. Slope Superficial Displacement Monitoring by Small Baseline SAR Interferometry Using Data from L-band ALOS PALSAR and X-band TerraSAR: A Case Study of Hong Kong, China

    Directory of Open Access Journals (Sweden)

    Fulong Chen

    2014-02-01

    Full Text Available Owing to the development of spaceborne synthetic aperture radar (SAR platforms, and in particular the increase in the availability of multi-source (multi-band and multi-resolution data, it is now feasible to design a surface displacement monitoring application using multi-temporal SAR interferometry (MT-InSAR. Landslides have high socio-economic impacts in many countries because of potential geo-hazards and heavy casualties. In this study, taking into account the merits of ALOS PALSAR (L-band, good coherence preservation and TerraSAR (X-band, high resolution and short revisit times data, we applied an improved small baseline InSAR (SB-InSAR with 3-D phase unwrapping approach, to monitor slope superficial displacement in Hong Kong, China, a mountainous subtropical zone city influenced by over-urbanization and heavy monsoonal rains. Results revealed that the synergistic use of PALSAR and TerraSAR data produces different outcomes in relation to data reliability and spatial-temporal resolution, and hence could be of significant value for a comprehensive understanding and monitoring of unstable slopes.

  5. Segment-based change detection for polarimetric SAR data

    DEFF Research Database (Denmark)

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

    2006-01-01

    that is needed compared to single polarisation SAR to provide reliable and robust detection of changes. Polarimetric SAR data will be available from satellites in the near future, e.g. the Japanese ALOS, the Canadian Radarsat-2 and the German TerraSAR-X. An appropriate way of representing multi-look fully...... be split into a number of smaller fields, a building may be removed from or added to some area, hedgerows may be removed/added or other type of vegetated areas may be partly removed or added. In this case, ambiguities may arise when segments have changed shape and extent from one image to another...

  6. Crop Classification Using Short-Revisit Multitemporal SAR Data

    DEFF Research Database (Denmark)

    Skriver, Henning; Mattia, Francesco; Satalino, Giuseppe

    2011-01-01

    Classification of crops and other land cover types is an important application of both optical/infrared and SAR satellite data. It is already an import application of present satellite systems, as it will be for planned missions, such as the Sentinels. An airborne SAR data set with a short revisi...

  7. Localized landslide risk assessment with multi pass L band DInSAR analysis

    Science.gov (United States)

    Yun, HyeWon; Rack Kim, Jung; Lin, Shih-Yuan; Choi, YunSoo

    2014-05-01

    In terms of data availability and error correction, landslide forecasting by Differential Interferometric SAR (DInSAR) analysis is not easy task. Especially, the landslides by the anthropogenic construction activities frequently occurred in the localized cutting side of mountainous area. In such circumstances, it is difficult to attain sufficient enough accuracy because of the external factors inducing the error component in electromagnetic wave propagation. For instance, the local climate characteristics such as orographic effect and the proximity to water source can produce the significant anomalies in the water vapor distribution and consequently result in the error components of InSAR phase angle measurements. Moreover the high altitude parts of target area cause the stratified tropospheric delay error in DInSAR measurement. The other obstacle in DInSAR observation over the potential landside site is the vegetation canopy which causes the decorrelation of InSAR phase. Thus rather than C band sensor such as ENVISAT, ERS and RADARSAT, DInSAR analysis with L band ALOS PLASAR is more recommendable. Together with the introduction of L band DInSAR analysis, the improved DInSAR technique to cope all above obstacles is necessary. Thus we employed two approaches i.e. StaMPS/MTI (Stanford Method for Persistent Scatterers/Multi-Temporal InSAR, Hopper et al., 2007) which was newly developed for extracting the reliable deformation values through time series analysis and two pass DInSAR with the error term compensation based on the external weather information in this study. Since the water vapor observation from spaceborne radiometer is not feasible by the temporal gap in this case, the quantities from weather Research Forecasting (WRF) with 1 km spatial resolution was used to address the atmospheric phase error in two pass DInSAR analysis. Also it was observed that base DEM offset with time dependent perpendicular baselines of InSAR time series produce a significant error

  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. Potential of TCPInSAR in Monitoring Linear Infrastructure with a Small Dataset of SAR Images: Application of the Donghai Bridge, China

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2018-03-01

    Full Text Available Reliably monitoring deformation associated with linear infrastructures, such as long-span bridges, is vitally important to assess their structural health. In this paper, we attempt to employ satellite interferometric synthetic aperture radar (InSAR to map the deformation of Donghai Bridge over a half of an annual cycle. The bridge, as the fourth longest cross-sea bridge in the world, located in the north of Hangzhou Bay, East China Sea where the featureless sea surface largely occupied the radar image raises challenges to accurately co-register the coherent points along the bridge. To tackle the issues due to co-registration and the limited number of synthetic aperture radar (SAR images, we adopt the termed temporarily-coherent point (TCP InSAR (TCPInSAR technique to process the radar images. TCPs that are not necessarily coherent during the whole observation period can be identified within every two SAR acquisitions during the co-registration procedure based on the statistics of azimuth and range offsets. In the process, co-registration is performed only using the offsets of these TCPs, leading to improved interferometric phases and the local Delaunay triangulation is used to construct point pairs to reduce the atmospheric artifacts along the bridge. With the TCPInSAR method the deformation rate along the bridge is estimated with no need of phase unwrapping. The achieved result reveals that the Donghai Bridge suffered a line-of-sight (LOS deformation rate up to −2.3 cm/year from January 2009 to July 2009 at the cable-stayed part, which is likely due to the thermal expansion of cables.

  10. Conducta alimentaria de Daphnia ambigua Scourfield 1947, Moina micrura Kurz 1874 y Ceriodaphnia dubia Richard 1895 (Cladocera frente a un gradiente de concentración de alimento Feeding behaviour of Daphnia ambigua Scourfield 1947, Moina micrura Kurz 1874 and Ceriodaphnia dubia Richard 1895 (Cladocera under a food concentration gradient

    Directory of Open Access Journals (Sweden)

    GINGER MARTINEZ

    2000-03-01

    Full Text Available Debido a que Cladocera es el grupo de microfiltradores más abundante del zooplancton límnico y cuyas poblaciones se encuentran usualmente limitadas por alimento, la respuesta de los individuos frente a un gradiente de concentración de recursos tendría significativas implicancias sobre los patrones poblacionales y comunitarios. Se comparó la conducta alimentaria de Moina micrura, Ceriodaphnia dubia y Daphnia ambigua (Cladocera frente a las microalgas Chlorella sp. y Oocystis sp. (Chlorophyceae mediante los siguientes parámetros: Tasa de Ingesta Máxima (Imax, Concentración Limitante Incipiente (CLI y Eficiencia de Consumo (b, los cuales fueron obtenidos a través de un modelo de respuesta funcional. Los resultados mostraron que D. ambigua presentó las mayores Imax y CLI sobre ambos recursos, sin embargo, esta especie presentó la menor b. Mientras que D. ambigua no presentó diferencias en b sobre Chlorella sp. y Oocystis sp., M. micrura presentó una mayor b sobre Chlorella sp. y C. dubia sobre Oocystis sp. Estos resultados revelan significativas diferencias interespecíficas en la respuesta alimentaria de Cladocera, grupo que presentó un complejo comportamiento frente a variaciones en la disponibilidad de recursos alimentariosBecause Cladocera is the most abundant group of filter-feeders in the freshwater zooplankton and their populations are usually found under limited resources conditions, the individual response under a resources concentration gradient has important consequences on the population and community patterns. Feeding behavior of Moina micrura, Ceriodaphnia dubia and Daphnia ambigua (Cladocera on the microalgae Chlorella sp. and Oocystis sp. (Chlorophyceae was compared by using the following parameters: Maximum Ingestion Rate (Imax, Incipient Limiting Concentration (ILC and Consumption Efficiency (b, which were obtained through a model of functional response. Results indicated that D. ambigua showed the highest Imax and

  11. 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.

  12. Performance Analysis for Airborne Interferometric SAR Affected by Flexible Baseline Oscillation

    Directory of Open Access Journals (Sweden)

    Liu Zhong-sheng

    2014-04-01

    Full Text Available The airborne interferometric SAR platform suffers from instability factors, such as air turbulence and mechanical vibrations during flight. Such factors cause the oscillation of the flexible baseline, which leads to significant degradation of the performance of the interferometric SAR system. This study is concerned with the baseline oscillation. First, the error of the slant range model under baseline oscillation conditions is formulated. Then, the SAR complex image signal and dual-channel correlation coefficient are modeled based on the first-order, second-order, and generic slant range error. Subsequently, the impact of the baseline oscillation on the imaging and interferometric performance of the SAR system is analyzed. Finally, simulations of the echo data are used to validate the theoretical analysis of the baseline oscillation in the airborne interferometric SAR.

  13. Space Radar Image of West Texas - SAR scan

    Science.gov (United States)

    1999-01-01

    This radar image of the Midland/Odessa region of West Texas, demonstrates an experimental technique, called ScanSAR, that allows scientists to rapidly image large areas of the Earth's surface. The large image covers an area 245 kilometers by 225 kilometers (152 miles by 139 miles). It was obtained by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) flying aboard the space shuttle Endeavour on October 5, 1994. The smaller inset image is a standard SIR-C image showing a portion of the same area, 100 kilometers by 57 kilometers (62 miles by 35 miles) and was taken during the first flight of SIR-C on April 14, 1994. The bright spots on the right side of the image are the cities of Odessa (left) and Midland (right), Texas. The Pecos River runs from the top center to the bottom center of the image. Along the left side of the image are, from top to bottom, parts of the Guadalupe, Davis and Santiago Mountains. North is toward the upper right. Unlike conventional radar imaging, in which a radar continuously illuminates a single ground swath as the space shuttle passes over the terrain, a Scansar radar illuminates several adjacent ground swaths almost simultaneously, by 'scanning' the radar beam across a large area in a rapid sequence. The adjacent swaths, typically about 50 km (31 miles) wide, are then merged during ground processing to produce a single large scene. Illumination for this L-band scene is from the top of the image. The beams were scanned from the top of the scene to the bottom, as the shuttle flew from left to right. This scene was acquired in about 30 seconds. A normal SIR-C image is acquired in about 13 seconds. The ScanSAR mode will likely be used on future radar sensors to construct regional and possibly global radar images and topographic maps. The ScanSAR processor is being designed for 1996 implementation at NASA's Alaska SAR Facility, located at the University of Alaska Fairbanks, and will produce digital images from the

  14. Genomic Characterization of Two Novel SAR11 Isolates From the Red Sea, Including the First Strain of the SAR11 Ib clade

    KAUST Repository

    Jimenez Infante, Francy M.

    2017-06-22

    The SAR11 clade (Pelagibacterales) is a diverse group that forms a monophyletic clade within the Alphaproteobacteria, and constitutes up to one third of all prokaryotic cells in the photic zone of most oceans. Pelagibacterales are very abundant in the warm and highly saline surface waters of the Red Sea, raising the question of adaptive traits of SAR11 populations in this water body and warmer oceans through the world. In this study, two pure cultures were successfully obtained from surface waters on the Red Sea, one isolate of subgroup Ia and one of the previously uncultured SAR11 Ib lineage. The novel genomes were very similar to each other and to genomes of isolates of SAR11 subgroup Ia (Ia pan-genome), both in terms of gene content and synteny. Among the genes that were not present in the Ia pan-genome, 108 (RS39, Ia) and 151 genes (RS40, Ib) were strain-specific. Detailed analyses showed that only 51 (RS39, Ia) and 55 (RS40, Ib) of these strain-specific genes had not reported before on genome fragments of Pelagibacterales. Further analyses revealed the potential production of phosphonates by some SAR11 members and possible adaptations for oligotrophic life, including pentose sugar utilization and adhesion to marine particulate matter.

  15. Genomic Characterization of Two Novel SAR11 Isolates From the Red Sea, Including the First Strain of the SAR11 Ib clade

    KAUST Repository

    Jimenez Infante, Francy M.; Ngugi, David; Vinu, Manikandan; Blom, Jochen; Alam, Intikhab; Bajic, Vladimir B.; Stingl, Ulrich

    2017-01-01

    The SAR11 clade (Pelagibacterales) is a diverse group that forms a monophyletic clade within the Alphaproteobacteria, and constitutes up to one third of all prokaryotic cells in the photic zone of most oceans. Pelagibacterales are very abundant in the warm and highly saline surface waters of the Red Sea, raising the question of adaptive traits of SAR11 populations in this water body and warmer oceans through the world. In this study, two pure cultures were successfully obtained from surface waters on the Red Sea, one isolate of subgroup Ia and one of the previously uncultured SAR11 Ib lineage. The novel genomes were very similar to each other and to genomes of isolates of SAR11 subgroup Ia (Ia pan-genome), both in terms of gene content and synteny. Among the genes that were not present in the Ia pan-genome, 108 (RS39, Ia) and 151 genes (RS40, Ib) were strain-specific. Detailed analyses showed that only 51 (RS39, Ia) and 55 (RS40, Ib) of these strain-specific genes had not reported before on genome fragments of Pelagibacterales. Further analyses revealed the potential production of phosphonates by some SAR11 members and possible adaptations for oligotrophic life, including pentose sugar utilization and adhesion to marine particulate matter.

  16. SAR compliance assessment of PMR 446 and FRS walkie-talkies.

    Science.gov (United States)

    Vermeeren, Günter; Joseph, Wout; Martens, Luc

    2015-10-01

    The vast amount of studies on radiofrequency dosimetry deal with exposure due to mobile devices and base station antennas for cellular communication systems. This study investigates compliance of walkie-talkies to exposure guidelines established by the International Commission on Non-Ionizing Radiation Protection and the Federal Communications Committee. The generic walkie-talkie consisted of a helical antenna and a ground plane and was derived by reverse engineering of a commercial walkie-talkie. Measured and simulated values of antenna characteristics and electromagnetic near fields of the generic walkie-talkie were within 2% and 8%, respectively. We also validated normalized electromagnetic near fields of the generic walkie-talkie against a commercial device and observed a very good agreement (deviation based on magnetic near field. Finally, we found that SAR of commercial devices is within current SAR limits for general public exposure for a worst-case duty cycle of 100%, that is, about 3 times and 6 times lower than the limit on the 1 g SAR (1.6 W/kg) and 10 g SAR (2 W/kg), respectively. But, an effective radiated power as specified by the Private Mobile Radio at 446 MHz (PMR 446) radio standard can cause localized SAR exceeding SAR limits for 1 g of tissue. © 2015 Wiley Periodicals, Inc.

  17. Estimating soil moisture using the Danish polarimetric SAR

    DEFF Research Database (Denmark)

    Jiankang, Ji; Thomsen, A.; Skriver, Henning

    1995-01-01

    The results of applying data from the Danish polarimetric SAR (EMISAR) to estimate soil moisture for bare fields are presented. Fully calibrated C-band SAR images for hh, vv and cross polarizations have been used in this study. The measured surface roughness data showed that classical roughness a...... of surface parameters with the bilinear model, the correlation coefficient between the estimated and measured soil moisture, as well as rms height, is about 0.77. To improve the result, the local incidence angles need to be taken into account......The results of applying data from the Danish polarimetric SAR (EMISAR) to estimate soil moisture for bare fields are presented. Fully calibrated C-band SAR images for hh, vv and cross polarizations have been used in this study. The measured surface roughness data showed that classical roughness...... autocorrelation functions (Gaussian and Exponential) were not able to fit natural surfaces well. A Gauss-Exp hybrid model which agreed better with the measured data has been proposed. Theoretical surface scattering models (POM, IEM), as well as an empirical model for retrieval of soil moisture and surface rms...

  18. 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....

  19. On Signal Modeling of Moon-Based Synthetic Aperture Radar (SAR Imaging of Earth

    Directory of Open Access Journals (Sweden)

    Zhen Xu

    2018-03-01

    Full Text Available The Moon-based Synthetic Aperture Radar (Moon-Based SAR, using the Moon as a platform, has a great potential to offer global-scale coverage of the earth’s surface with a high revisit cycle and is able to meet the scientific requirements for climate change study. However, operating in the lunar orbit, Moon-Based SAR imaging is confined within a complex geometry of the Moon-Based SAR, Moon, and Earth, where both rotation and revolution have effects. The extremely long exposure time of Moon-Based SAR presents a curved moving trajectory and the protracted time-delay in propagation makes the “stop-and-go” assumption no longer valid. Consequently, the conventional SAR imaging technique is no longer valid for Moon-Based SAR. This paper develops a Moon-Based SAR theory in which a signal model is derived. The Doppler parameters in the context of lunar revolution with the removal of ‘stop-and-go’ assumption are first estimated, and then characteristics of Moon-Based SAR imaging’s azimuthal resolution are analyzed. In addition, a signal model of Moon-Based SAR and its two-dimensional (2-D spectrum are further derived. Numerical simulation using point targets validates the signal model and enables Doppler parameter estimation for image focusing.

  20. SAR Ambiguity Study for the Cassini Radar

    Science.gov (United States)

    Hensley, Scott; Im, Eastwood; Johnson, William T. K.

    1993-01-01

    The Cassini Radar's synthetic aperture radar (SAR) ambiguity analysis is unique with respect to other spaceborne SAR ambiguity analyses owing to the non-orbiting spacecraft trajectory, asymmetric antenna pattern, and burst mode of data collection. By properly varying the pointing, burst mode timing, and radar parameters along the trajectory this study shows that the signal-to-ambiguity ratio of better than 15 dB can be achieved for all images obtained by the Cassini Radar.

  1. 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...

  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...

  3. The integration of Human Factors (HF) in the SAR process training course text

    International Nuclear Information System (INIS)

    Ryan, T.G.

    1995-03-01

    This text provides the technical basis for a two-day course on human factors (HF), as applied to the Safety Analysis Report (SAR) process. The overall objective of this text and course is to: provide the participant with a working knowledge of human factors-related requirements, suggestions for doing a human safety analysis applying a graded approach, and an ability to demonstrate using the results of the human safety analysis, that human factors elements as defined by DOE (human factors engineering, procedures, training, oversight, staffing, qualifications), can support wherever necessary, nuclear safety commitments in the SAR. More specifically, the objectives of the text and course are: (1) To provide the SAR preparer with general guidelines for doing HE within the context of a graded approach for the SAR; (2) To sensitize DOE facility managers and staff, safety analysts and SAR preparers, independent reviewers, and DOE reviewers and regulators, to DOE Order 5480.23 requirements for HE in the SAR; (3) To provide managers, analysts, reviewers and regulators with a working knowledge of HE concepts and techniques within the context of a graded approach for the SAR, and (4) To provide SAR managers and DOE reviewers and regulators with general guidelines for monitoring and coordinating the work of preparers of HE inputs throughout the SAR process, and for making decisions regarding the safety relevance of HE inputs to the SAR. As a ready reference for implementing the human factors requirements of DOE Order 5480.22 and DOE Standard 3009-94, this course text and accompanying two-day course are intended for all persons who are involved in the SAR

  4. The integration of Human Factors (HF) in the SAR process training course text

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, T.G.

    1995-03-01

    This text provides the technical basis for a two-day course on human factors (HF), as applied to the Safety Analysis Report (SAR) process. The overall objective of this text and course is to: provide the participant with a working knowledge of human factors-related requirements, suggestions for doing a human safety analysis applying a graded approach, and an ability to demonstrate using the results of the human safety analysis, that human factors elements as defined by DOE (human factors engineering, procedures, training, oversight, staffing, qualifications), can support wherever necessary, nuclear safety commitments in the SAR. More specifically, the objectives of the text and course are: (1) To provide the SAR preparer with general guidelines for doing HE within the context of a graded approach for the SAR; (2) To sensitize DOE facility managers and staff, safety analysts and SAR preparers, independent reviewers, and DOE reviewers and regulators, to DOE Order 5480.23 requirements for HE in the SAR; (3) To provide managers, analysts, reviewers and regulators with a working knowledge of HE concepts and techniques within the context of a graded approach for the SAR, and (4) To provide SAR managers and DOE reviewers and regulators with general guidelines for monitoring and coordinating the work of preparers of HE inputs throughout the SAR process, and for making decisions regarding the safety relevance of HE inputs to the SAR. As a ready reference for implementing the human factors requirements of DOE Order 5480.22 and DOE Standard 3009-94, this course text and accompanying two-day course are intended for all persons who are involved in the SAR.

  5. Fusion method of SAR and optical images for urban object extraction

    Science.gov (United States)

    Jia, Yonghong; Blum, Rick S.; Li, Fangfang

    2007-11-01

    A new image fusion method of SAR, Panchromatic (Pan) and multispectral (MS) data is proposed. First of all, SAR texture is extracted by ratioing the despeckled SAR image to its low pass approximation, and is used to modulate high pass details extracted from the available Pan image by means of the á trous wavelet decomposition. Then, high pass details modulated with the texture is applied to obtain the fusion product by HPFM (High pass Filter-based Modulation) fusion method. A set of image data including co-registered Landsat TM, ENVISAT SAR and SPOT Pan is used for the experiment. The results demonstrate accurate spectral preservation on vegetated regions, bare soil, and also on textured areas (buildings and road network) where SAR texture information enhances the fusion product, and the proposed approach is effective for image interpret and classification.

  6. SIMULATION OF SHIP GENERATED TURBULENT AND VORTICAL WAKE IMAGING BY SAR

    Institute of Scientific and Technical Information of China (English)

    Wang Aiming; Zhu Minhui

    2004-01-01

    Synthetic Aperture Radar (SAR) imaging of ocean surface features is studied. The simulation of the turbulent and vortical features generated by a moving ship and SAR imaging of these wakes is carried out. The turbulent wake damping the ocean surface capillary waves may be partially responsible for the suppression of surface waves near the ship track. The vortex pair generating a change in the lateral flow field behind the ship may be partially responsible for an enhancement of the waves near the edges of the smooth area. These hydrodynamic phenomena as well as the changes of radar backscatter generated by turbulence and vortex are simulated.An SAR imaging model is then used on such ocean surface features to provide SAR images.Comparison of two ships' simulated SAR images shows that the wake features are different for various ship parameters.

  7. Risk factors for chronic post-traumatic stress disorder (PTSD) in SARS survivors.

    Science.gov (United States)

    Mak, Ivan Wing Chit; Chu, Chung Ming; Pan, Pey Chyou; Yiu, Michael Gar Chung; Ho, Suzanne C; Chan, Veronica Lee

    2010-01-01

    Post-traumatic stress disorder (PTSD) is one of the most prevalent long-term psychiatric diagnoses among survivors of severe acute respiratory syndrome (SARS). The objective of this study was to identify the predictors of chronic PTSD in SARS survivors. PTSD at 30 months after the SARS outbreak was assessed by the Structured Clinical Interview for the DSM-IV. Survivors' demographic data, medical information and psychosocial variables were collected for risk factor analysis. Multivariate logistic regression analysis showed that female gender as well as the presence of chronic medical illnesses diagnosed before the onset of SARS and avascular necrosis were independent predictors of PTSD at 30 months post-SARS. Associated factors included higher-chance external locus of control, higher functional disability and higher average pain intensity. The study of PTSD at 30 months post-SARS showed that the predictive value of acute medical variables may fade out. Our findings do not support some prior hypotheses that the use of high dose corticosteroids is protective against the development of PTSD. On the contrary, the adversity both before and after the SARS outbreak may be more important in hindering recovery from PTSD. The risk factor analysis can not only improve the detection of hidden psychiatric complications but also provide insight for the possible model of care delivery for the SARS survivors. With the complex interaction of the biopsychosocial challenges of SARS, an integrated multidisciplinary clinic setting may be a superior approach in the long-term management of complicated PTSD cases. Copyright © 2010 Elsevier Inc. All rights reserved.

  8. SAR Cross-Ambiguities in SAOCOM-CS Large Baseline Bistatic Configuration

    OpenAIRE

    Bordoni, Federica; Rodriguez-Cassola, Marc; Younis, Marwan; Prats-Iraola, Pau; Lopez-Dekker, Paco; Krieger, Gerhard

    2016-01-01

    The evaluation of the ambiguous signal level, the Ambiguity-to-Signal Ratio (ASR), plays a key role in the Synthetic Aperture Radar (SAR) design and performance prediction. In conventional SAR acquisition scenarios, the computation of the ASR is based on the evaluation of the range and azimuth ambiguous contributes. Though appealing for its simplicity, this approach could be inaccurate in case of complex SAR acquisition geometries. In this paper we focus on the ASR performance of the SAOCOM-...

  9. Rice Crop Monitoring and Yield Estimation Through Cosmo Skymed and TerraSAR-X: A SAR-Based Experience in India

    OpenAIRE

    Pazhanivelan, S.; Kannan, P.; Christy Nirmala Mary, P.; Subramanian, E.; Jeyaraman, S.; Nelson, A.; Setiyono, T.; Holecz, F.; Barbieri, M.; Yadav, M.

    2015-01-01

    Rice is the most important cereal crop governing food security in Asia. Reliable and regular information on the area under rice production is the basis of policy decisions related to imports, exports and prices which directly affect food security. Recent and planned launches of SAR sensors coupled with automated processing can provide sustainable solutions to the challenges on mapping and monitoring rice systems. High resolution (3m) Synthetic Aperture Radar (SAR) imageries were used...

  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. 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.

  12. Observed and predicted reproduction of Ceriodaphnia dubia exposed to chloride, sulfate, and bicarbonate

    Science.gov (United States)

    Lasier, Peter J.; Hardin, Ian R.

    2010-01-01

    Chronic toxicities of Cl-, SO42-, and HCO3- to Ceriodaphnia dubia were evaluated in low- and moderate-hardness waters using a three-brood reproduction test method. Toxicity tests of anion mixtures were used to determine interaction effects and to produce models predicting C. dubia reproduction. Effluents diluted with low- and moderate-hardness waters were tested with animals acclimated to low- and moderate-hardness conditions to evaluate the models and to assess the effects of hardness and acclimation. Sulfate was significantly less toxic than Cl- and HCO3- in both types of water. Chloride and HCO3- toxicities were similar in low-hardness water, but HCO3- was the most toxic in moderate-hardness water. Low acute-to-chronic ratios indicate that toxicities of these anions will decrease quickly with dilution. Hardness significantly reduced Cl- and SO42- toxicity but had little effect on HCO3-. Chloride toxicity decreased with an increase in Na+ concentration, and CO3- toxicity may have been reduced by the dissolved organic carbon in effluent. Multivariate models using measured anion concentrations in effluents with low to moderate hardness levels provided fairly accurate predictions of reproduction. Determinations of toxicity for several effluents differed significantly depending on the hardness of the dilution water and the hardness of the water used to culture test animals. These results can be used to predict the contribution of elevated anion concentrations to the chronic toxicity of effluents; to identify effluents that are toxic due to contaminants other than Cl-, SO42-, and HCO3-; and to provide a basis for chemical substitutions in manufacturing processes.

  13. 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.

  14. The Generalized Gamma-DBN for High-Resolution SAR Image Classification

    Directory of Open Access Journals (Sweden)

    Zhiqiang Zhao

    2018-06-01

    Full Text Available With the increase of resolution, effective characterization of synthetic aperture radar (SAR image becomes one of the most critical problems in many earth observation applications. Inspired by deep learning and probability mixture models, a generalized Gamma deep belief network (g Γ-DBN is proposed for SAR image statistical modeling and land-cover classification in this work. Specifically, a generalized Gamma-Bernoulli restricted Boltzmann machine (gΓB-RBM is proposed to capture high-order statistical characterizes from SAR images after introducing the generalized Gamma distribution. After stacking the g Γ B-RBM and several standard binary RBMs in a hierarchical manner, a gΓ-DBN is constructed to learn high-level representation of different SAR land-covers. Finally, a discriminative neural network is constructed by adding an additional predict layer for different land-covers over the constructed deep structure. Performance of the proposed approach is evaluated via several experiments on some high-resolution SAR image patch sets and two large-scale scenes which are captured by ALOS PALSAR-2 and COSMO-SkyMed satellites respectively.

  15. a Statistical Texture Feature for Building Collapse Information Extraction of SAR Image

    Science.gov (United States)

    Li, L.; Yang, H.; Chen, Q.; Liu, X.

    2018-04-01

    Synthetic Aperture Radar (SAR) has become one of the most important ways to extract post-disaster collapsed building information, due to its extreme versatility and almost all-weather, day-and-night working capability, etc. In view of the fact that the inherent statistical distribution of speckle in SAR images is not used to extract collapsed building information, this paper proposed a novel texture feature of statistical models of SAR images to extract the collapsed buildings. In the proposed feature, the texture parameter of G0 distribution from SAR images is used to reflect the uniformity of the target to extract the collapsed building. This feature not only considers the statistical distribution of SAR images, providing more accurate description of the object texture, but also is applied to extract collapsed building information of single-, dual- or full-polarization SAR data. The RADARSAT-2 data of Yushu earthquake which acquired on April 21, 2010 is used to present and analyze the performance of the proposed method. In addition, the applicability of this feature to SAR data with different polarizations is also analysed, which provides decision support for the data selection of collapsed building information extraction.

  16. Multi-Pixel Simultaneous Classification of PolSAR Image Using Convolutional Neural Networks

    Science.gov (United States)

    Xu, Xin; Gui, Rong; Pu, Fangling

    2018-01-01

    Convolutional neural networks (CNN) have achieved great success in the optical image processing field. Because of the excellent performance of CNN, more and more methods based on CNN are applied to polarimetric synthetic aperture radar (PolSAR) image classification. Most CNN-based PolSAR image classification methods can only classify one pixel each time. Because all the pixels of a PolSAR image are classified independently, the inherent interrelation of different land covers is ignored. We use a fixed-feature-size CNN (FFS-CNN) to classify all pixels in a patch simultaneously. The proposed method has several advantages. First, FFS-CNN can classify all the pixels in a small patch simultaneously. When classifying a whole PolSAR image, it is faster than common CNNs. Second, FFS-CNN is trained to learn the interrelation of different land covers in a patch, so it can use the interrelation of land covers to improve the classification results. The experiments of FFS-CNN are evaluated on a Chinese Gaofen-3 PolSAR image and other two real PolSAR images. Experiment results show that FFS-CNN is comparable with the state-of-the-art PolSAR image classification methods. PMID:29510499

  17. 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.

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

    Science.gov (United States)

    Giovannoni, Stephen J

    2017-01-03

    SAR11 is a group of small, carbon-oxidizing bacteria that reach a global estimated population size of 2.4×10 28 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.

  19. Multi-temporal and Dual-polarization Interferometric SAR for Land Cover Type Classification

    Directory of Open Access Journals (Sweden)

    WANG Xinshuang

    2015-05-01

    Full Text Available In order to study SAR land cover classification method, this paper uses the multi-dimensional combination of temporal,polarization and InSAR data. The area covered by space borne data of ALOS PALSAR in Xunke County,Heilongjiang Province was chosen as test site. A land cover classification technique of SVM based on multi-temporal, multi-polarization and InSAR data had been proposed, using the sensitivity to land cover type of multi-temporal, multi-polarization SAR data and InSAR measurements, and combing time series characteristic of backscatter coefficient and correlation coefficient to identify ground objects. The results showed the problem of confusion between forest land and urban construction land can be nicely solved, using the correlation coefficient between HH and HV, and also combing the selected temporal, polarization and InSAR characteristics. The land cover classification result with higher accuracy is gotten using the classification algorithm proposed in this paper.

  20. New free Danish online (Q)SAR predictions database with >600,000 substances

    DEFF Research Database (Denmark)

    Wedebye, Eva Bay; Dybdahl, Marianne; Reffstrup, Trine Klein

    Since 2005 the Danish (Q)SAR Database has been freely available on the Internet. It is a tool that allows single chemical substance profiling and screenings based on predicted hazard information. The database is also included in the OECD (Q)SAR Application Toolbox which is used worldwide...... by regulators and industry. A lot of progress in (Q)SAR model development, application and documentation has been made since the publication in 2005. A new and completely rebuild online (Q)SAR predictions database was therefore published in November 2015 at http://qsar.food.dtu.dk. The number of chemicals...... in the database has been expanded from 185,000 to >600,000. As far as possible all organic single constituent substances that were pre-registered under REACH have been included in the new structure set. The new Danish (Q)SAR Database includes estimates from more than 200 (Q)SARs covering a wide range of hazardous...

  1. What is missing? An operational inundation mapping framework by SAR data

    Science.gov (United States)

    Shen, X.; Anagnostou, E. N.; Zeng, Z.; Kettner, A.; Hong, Y.

    2017-12-01

    Compared to optical sensors, synthetic aperture radar (SAR) works all-day all-weather. In addition, its spatial resolution does not decrease with the height of the platform and is thus applicable to a range of important studies. However, existing studies did not address the operational demands of real-time inundation mapping. The direct proof is that no water body product exists for any SAR-based satellites. Then what is missing between science and products? Automation and quality. What makes it so difficult to develop an operational inundation mapping technique based on SAR data? Spectrum-wise, unlike optical water indices such as MNDWI, AWEI etc., where a relative constant threshold may apply across acquisition of images, regions and sensors, the threshold to separate water from non-water pixels in each SAR images has to be individually chosen. The optimization of the threshold is the first obstacle to the automation of the SAR data algorithm. Morphologically, the quality and reliability of the results have been compromised by over-detection caused by smooth surface and shadowing area, the noise-like speckle and under-detection caused by strong-scatter disturbance. In this study, we propose a three-step framework that addresses all aforementioned issues of operational inundation mapping by SAR data. The framework consists of 1) optimization of Wishart distribution parameters of single/dual/fully-polarized SAR data, 2) morphological removal of over-detection, and 3) machine-learning based removal of under-detection. The framework utilizes not only the SAR data, but also the synergy of digital elevation model (DEM), and optical sensor-based products of fine resolution, including the water probability map, land cover classification map (optional), and river width. The framework has been validated throughout multiple areas in different parts of the world using different satellite SAR data and globally available ancillary data products. Therefore, it has the potential

  2. 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...... (WRF) model in high resolution and WRF with coupled microscale parametrization....

  3. Genomic characterization of two novel SAR11 isolates from the Red Sea, including the first strain of the SAR11 Ib clade.

    Science.gov (United States)

    Jimenez-Infante, Francy; Ngugi, David Kamanda; Vinu, Manikandan; Blom, Jochen; Alam, Intikhab; Bajic, Vladimir B; Stingl, Ulrich

    2017-07-01

    The SAR11 clade (Pelagibacterales) is a diverse group that forms a monophyletic clade within the Alphaproteobacteria, and constitutes up to one third of all prokaryotic cells in the photic zone of most oceans. Pelagibacterales are very abundant in the warm and highly saline surface waters of the Red Sea, raising the question of adaptive traits of SAR11 populations in this water body and warmer oceans through the world. In this study, two pure cultures were successfully obtained from surface waters on the Red Sea: one isolate of subgroup Ia and one of the previously uncultured SAR11 Ib lineage. The novel genomes were very similar to each other and to genomes of isolates of SAR11 subgroup Ia (Ia pan-genome), both in terms of gene content and synteny. Among the genes that were not present in the Ia pan-genome, 108 (RS39, Ia) and 151 genes (RS40, Ib) were strain specific. Detailed analyses showed that only 51 (RS39, Ia) and 55 (RS40, Ib) of these strain-specific genes had not reported before on genome fragments of Pelagibacterales. Further analyses revealed the potential production of phosphonates by some SAR11 members and possible adaptations for oligotrophic life, including pentose sugar utilization and adhesion to marine particulate matter. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. TOWARDS CHANGE DETECTION IN URBAN AREA BY SAR INTERFEROMETRY AND RADARGRAMMETRY

    Directory of Open Access Journals (Sweden)

    C. Dubois

    2013-04-01

    Full Text Available Change detection in urban area is an active topic in remote sensing. However, well-dealt subject in optical remote sensing, this research topic is still at an early stage and needs deeper investigations and improvement in what concerns SAR and InSAR remote sensing. Due to their weather and daylight-independency, SAR sensors allow an all-time observation of the earth. This is determining in cases where rapid change detection is required after a natural – or technological – disaster. Due to the high resolution that can be achieved, the new generation of space-borne radar sensors opens up new perspectives for analysing buildings in urban areas. Moreover, due to their short revisiting cycle, they give rise to monitoring and change detection applications. In this paper, we present a concept for change detection in urban area at building level, relying only on SAR- and InSAR data. In this approach, interferometric and radargrammetric SAR data are merged in order to detect changes. Here, we present the overall workflow, the test area, the required data as well as first findings on the best-suited stereo-configurations for change detection.

  5. SAR China Land Mapping Project: Development, Production and Potential Applications

    International Nuclear Information System (INIS)

    Zhang, Lu; Guo, Huadong; Liu, Guang; Fu, Wenxue; Yan, Shiyong; Song, Rui; Ji, Peng; Wang, Xinyuan

    2014-01-01

    Large-area, seamless synthetic aperture radar (SAR) mosaics can reflect overall environmental conditions and highlight general trends in observed areas from a macroscopic standpoint, and effectively support research at the global scale, which is in high demand now across scientific fields. The SAR China Land Mapping Project (SCLM), supported by the Digital Earth Science Platform Project initiated and managed by the Center for Earth Observation and Digital Earth, Chinese Academy of Sciences (CEODE), is introduced in this paper. This project produced a large-area SAR mosaic dataset and generated the first complete seamless SAR map covering the entire land area of China using EnviSat-ASAR images. The value of the mosaic map is demonstrated by some potential applications in studies of urban distribution, rivers and lakes, geologic structures, geomorphology and paleoenvironmental change

  6. Vegetation Parameter Extraction Using Dual Baseline Polarimetric SAR Interferometry Data

    Science.gov (United States)

    Zhang, H.; Wang, C.; Chen, X.; Tang, Y.

    2009-04-01

    For vegetation parameter inversion, the single baseline polarimetric SAR interferometry (POLinSAR) technique, such as the three-stage method and the ESPRIT algorithm, is limited by the observed data with the minimum ground to volume amplitude ration, which effects the estimation of the effective phase center for the vegetation canopy or the surface, and thus results in the underestimated vegetation height. In order to remove this effect of the single baseline inversion techniques in some extend, another baseline POLinSAR data is added on vegetation parameter estimation in this paper, and a dual baseline POLinSAR technique for the extraction of the vegetation parameter is investigated and improved to reduce the dynamic bias for the vegetation parameter estimation. Finally, the simulated data and real data are used to validate this dual baseline technique.

  7. Exploring cloud and big data components for SAR archiving and analysis

    Science.gov (United States)

    Baker, S.; Crosby, C. J.; Meertens, C.; Phillips, D.

    2017-12-01

    Under the Geodesy Advancing Geoscience and EarthScope (GAGE) NSF Cooperative Agreement, UNAVCO has seen the volume of the SAR Data Archive grow at a substantial rate, from 2 TB in Y1 and 5 TB in Y2 to 41 TB in Y3 primarily due to WInSAR PI proposal management of ALOS-­2/JAXA (Japan Aerospace Exploration Agency) data and to a lesser extent Supersites and other data collections. JAXA provides a fixed number of scenes per year for each PI, and some data files are 50­-60GB each, which accounts for the large volume of data. In total, over 100TB of SAR data are in the WInSAR/UNAVCO archive and a large portion of these are available unrestricted for WInSAR members. In addition to the existing data, newer data streams from the Sentinel-1 and NISAR missions will require efficient processing pipelines and easily scalable infrastructure to handle processed results. With these growing data sizes and space concerns, the SAR archive operations migrated to the Texas Advanced Computing Center (TACC) via an NSF XSEDE proposal in spring 2017. Data are stored on an HPC system while data operations are running on Jetstream virtual machines within the same datacenter. In addition to the production data operations, testing was done in early 2017 with container based InSAR processing analysis using JupyterHub and Docker images deployed on a VM cluster on Jetstream. The JupyterHub environment is well suited for short courses and other training opportunities for the community such as labs for university courses on InSAR. UNAVCO is also exploring new processing methodologies using DC/OS (the datacenter operating system) for batch and stream processing workflows and time series analysis with Big Data open source components like the Spark, Mesos, Akka, Cassandra, Kafka (SMACK) stack. The comparison of the different methodologies will provide insight into the pros and cons for each and help the SAR community with decisions about infrastructure and software requirements to meet their research

  8. Calibration of SAR probes in waveguide at 900 MHz

    International Nuclear Information System (INIS)

    Jokela, K.; Puranen, L.; Hyysalo, P.

    1998-01-01

    The radiation safety tests for hand-held mobile phones require precise calibration of the small electric field probes used for the measurement of SAR in phantoms simulating the human body. In this study a calibration based on a rectangular waveguide was developed for SAR calibrations at 900 MHz

  9. Project PHARUS: Towards a polarimetric C-band airborne SAR

    NARCIS (Netherlands)

    Hoogeboom, P.; Koomen, P.J.; Otten, M.P.G.; Pouwels, H.; Snoeij, P.

    1989-01-01

    A few years ago three institutes in the Netherlands developed a plan to design and build a polarimetric C-band aircraft SAR system of a novel design, called PHARUS (PHased Array Universal SAR), meant as a replacement for our current digital SLAR system. These institutes are the Physics and

  10. Immune responses against SARS-coronavirus nucleocapsid protein induced by DNA vaccine

    International Nuclear Information System (INIS)

    Zhao Ping; Cao Jie; Zhao Lanjuan; Qin Zhaolin; Ke Jinshan; Pan Wei; Ren Hao; Yu Jianguo; Qi Zhongtian

    2005-01-01

    The nucleocapsid (N) protein of SARS-coronavirus (SARS-CoV) is the key protein for the formation of the helical nucleocapsid during virion assembly. This protein is believed to be more conserved than other proteins of the virus, such as spike and membrane glycoprotein. In this study, the N protein of SARS-CoV was expressed in Escherichia coli DH5α and identified with pooled sera from patients in the convalescence phase of SARS. A plasmid pCI-N, encoding the full-length N gene of SARS-CoV, was constructed. Expression of the N protein was observed in COS1 cells following transfection with pCI-N. The immune responses induced by intramuscular immunization with pCI-N were evaluated in a murine model. Serum anti-N immunoglobulins and splenocytes proliferative responses against N protein were observed in immunized BALB/c mice. The major immunoglobulin G subclass recognizing N protein was immunoglobulin G2a, and stimulated splenocytes secreted high levels of gamma interferon and IL-2 in response to N protein. More importantly, the immunized mice produced strong delayed-type hypersensitivity (DTH) and CD8 + CTL responses to N protein. The study shows that N protein of SARS-CoV not only is an important B cell immunogen, but also can elicit broad-based cellular immune responses. The results indicate that the N protein may be of potential value in vaccine development for specific prophylaxis and treatment against SARS

  11. Change Detection with Polarimetric SAR Imagery for Nuclear Verification

    International Nuclear Information System (INIS)

    Canty, M.

    2015-01-01

    This paper investigates the application of multivariate statistical change detection with high-resolution polarimetric SAR imagery acquired from commercial satellite platforms for observation and verification of nuclear activities. A prototype software tool comprising a processing chain starting from single look complex (SLC) multitemporal data through to change detection maps is presented. Multivariate change detection algorithms applied to polarimetric SAR data are not common. This is because, up until recently, not many researchers or practitioners have had access to polarimetric data. However with the advent of several spaceborne polarimetric SAR instruments such as the Japanese ALOS, the Canadian Radarsat-2, the German TerraSAR-X, the Italian COSMO-SkyMed missions and the European Sentinal SAR platform, the situation has greatly improved. There is now a rich source of weather-independent satellite radar data which can be exploited for Nuclear Safeguards purposes. The method will also work for univariate data, that is, it is also applicable to scalar or single polarimetric SAR data. The change detection procedure investigated here exploits the complex Wishart distribution of dual and quad polarimetric imagery in look-averaged covariance matrix format in order to define a per-pixel change/no-change hypothesis test. It includes approximations for the probability distribution of the test statistic, and so permits quantitative significance levels to be quoted for change pixels. The method has been demonstrated previously with polarimetric images from the airborne EMISAR sensor, but is applied here for the first time to satellite platforms. In addition, an improved multivariate method is used to estimate the so-called equivalent number of looks (ENL), which is a critical parameter of the hypothesis test. (author)

  12. Different modes of TiO2 uptake by Ceriodaphnia dubia: relevance to toxicity and bioaccumulation.

    Science.gov (United States)

    Dalai, Swayamprava; Iswarya, V; Bhuvaneshwari, M; Pakrashi, Sunandan; Chandrasekaran, N; Mukherjee, Amitava

    2014-07-01

    The extensive environmental exposure of engineered metal oxide nanoparticles (NPs) may result in their bioaccumulation in aquatic organisms leading to their biotransfer in a food chain through various routes in a freshwater ecosystem. The present study focuses on the possible modes of TiO2 NP trophic transfer to Ceriodaphnia dubia, in presence and/absence of its diet, Scenedesmus obliquus (primary producer). The acute exposure studies (48h) were designed to have daphnids exposed to (i) the free NPs, (ii) both the free and the algae-borne NPs; and (iii) only the algae-borne NPs in separate tests to understand the possible routes of NP transfer. The dietary uptake of TiO2 NPs (algae-borne) was found to be the primary route for NP biotransfer with ∼70% of total NP uptake. Interestingly, in a separate study it was noticed that the NPs coated with algal exudates were easily taken up by daphnids as compared to pristine NPs of same concentrations, leading to their higher bioaccumulation. A chronic toxicity study, where daphnids were exposed to both free and algae-borne NPs for 21 days was undertaken to comprehend the TiO2 NP effect on daphnia growth and reproduction upon chronic exposure and also the bioaccumulation potential. Both acute and chronic exposure studies suggested higher bioaccumulation of TiO2 in daphnids when the particles were less toxic to the diet (algae). Copyright © 2014 Elsevier B.V. All rights reserved.

  13. From genome to antivirals: SARS as a test tube.

    Science.gov (United States)

    Kliger, Yossef; Levanon, Erez Y; Gerber, Doron

    2005-03-01

    The severe acute respiratory syndrome (SARS) epidemic brought into the spotlight the need for rapid development of effective anti-viral drugs against newly emerging viruses. Researchers have leveraged the 20-year battle against AIDS into a variety of possible treatments for SARS. Most prominently, based solely on viral genome information, silencers of viral genes, viral-enzyme blockers and viral-entry inhibitors were suggested as potential therapeutic agents for SARS. In particular, inhibitors of viral entry, comprising therapeutic peptides, were based on the recently launched anti-HIV drug enfuvirtide. This could represent one of the most direct routes from genome sequencing to the discovery of antiviral drugs.

  14. Target discrimination method for SAR images based on semisupervised co-training

    Science.gov (United States)

    Wang, Yan; Du, Lan; Dai, Hui

    2018-01-01

    Synthetic aperture radar (SAR) target discrimination is usually performed in a supervised manner. However, supervised methods for SAR target discrimination may need lots of labeled training samples, whose acquirement is costly, time consuming, and sometimes impossible. This paper proposes an SAR target discrimination method based on semisupervised co-training, which utilizes a limited number of labeled samples and an abundant number of unlabeled samples. First, Lincoln features, widely used in SAR target discrimination, are extracted from the training samples and partitioned into two sets according to their physical meanings. Second, two support vector machine classifiers are iteratively co-trained with the extracted two feature sets based on the co-training algorithm. Finally, the trained classifiers are exploited to classify the test data. The experimental results on real SAR images data not only validate the effectiveness of the proposed method compared with the traditional supervised methods, but also demonstrate the superiority of co-training over self-training, which only uses one feature set.

  15. Investigation of the Capability of Compact Polarimetric SAR Interferometry to Estimate Forest Height

    Science.gov (United States)

    Zhang, Hong; Xie, Lei; Wang, Chao; Chen, Jiehong

    2013-08-01

    The main objective of this paper is to investigate the capability of compact Polarimetric SAR Interferometry (C-PolInSAR) on forest height estimation. For this, the pseudo fully polarimetric interferomteric (F-PolInSAR) covariance matrix is firstly reconstructed, then the three- stage inversion algorithm, hybrid algorithm, Music and Capon algorithm are applied to both C-PolInSAR covariance matrix and pseudo F-PolInSAR covariance matrix. The availability of forest height estimation is demonstrated using L-band data generated by simulator PolSARProSim and X-band airborne data acquired by East China Research Institute of Electronic Engineering, China Electronics Technology Group Corporation.

  16. Information theoretic bounds for compressed sensing in SAR imaging

    International Nuclear Information System (INIS)

    Jingxiong, Zhang; Ke, Yang; Jianzhong, Guo

    2014-01-01

    Compressed sensing (CS) is a new framework for sampling and reconstructing sparse signals from measurements significantly fewer than those prescribed by Nyquist rate in the Shannon sampling theorem. This new strategy, applied in various application areas including synthetic aperture radar (SAR), relies on two principles: sparsity, which is related to the signals of interest, and incoherence, which refers to the sensing modality. An important question in CS-based SAR system design concerns sampling rate necessary and sufficient for exact or approximate recovery of sparse signals. In the literature, bounds of measurements (or sampling rate) in CS have been proposed from the perspective of information theory. However, these information-theoretic bounds need to be reviewed and, if necessary, validated for CS-based SAR imaging, as there are various assumptions made in the derivations of lower and upper bounds on sub-Nyquist sampling rates, which may not hold true in CS-based SAR imaging. In this paper, information-theoretic bounds of sampling rate will be analyzed. For this, the SAR measurement system is modeled as an information channel, with channel capacity and rate-distortion characteristics evaluated to enable the determination of sampling rates required for recovery of sparse scenes. Experiments based on simulated data will be undertaken to test the theoretic bounds against empirical results about sampling rates required to achieve certain detection error probabilities

  17. 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.

  18. Research on Strong Clutter Suppression for Gaofen-3 Dual-Channel SAR/GMTI

    Directory of Open Access Journals (Sweden)

    Mingjie Zheng

    2018-03-01

    Full Text Available In spaceborne synthetic aperture radar (SAR, moving targets are almost buried in ground clutter due to the wide clutter Doppler spectrum and the restricted pulse repetition frequency (PRF, which increases the difficulty of moving target detection. Clutter suppression is one of the key issues in the spaceborne SAR moving target indicator operation. In this paper, we describe the clutter suppression principle and analyze the influence of amplitude and phase error on clutter suppression. In the following, a novel dual-channel SAR clutter suppression algorithm is proposed, which is suitable for the Gaofen-3(GF-3 SAR sensor. The proposed algorithm consists of three technique steps, namely adaptive two-dimensional (2D channel calibration, refined amplitude error correction and refined phase error correction. After channel error is corrected by these procedures, the clutter component, especially a strong clutter component, can be well suppressed. The validity of the proposed algorithm is verified by GF-3 SAR real data which demonstrates the ground moving-target indication (GMTI capability of GF-3 SAR sensor.

  19. Advanced InSAR imaging for dune mapping

    Science.gov (United States)

    Havivi, Shiran; August, Yitzhak; Blumberg, Dan G.; Rotman, Stanley R.

    2015-04-01

    Aeolian morphologies are formed in the presence of sufficient wind energy and available particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970's, remote sensing imagery both optical and radar, are used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of Aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two images or more. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This research aims to demonstrate how interferometric decorrelation, or, coherence change detection, can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the Nitzanim coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of varying levels of stability and vegetation cover and have been monitored meteorologically, geomorphologically and

  20. Latitudinal dynamics of SAR-arcs relative to the local time

    International Nuclear Information System (INIS)

    Alekseev, V.N.; Ievenko, I.B.

    1991-01-01

    In November-December, 1988, January-April, 1989-1990, at the Maymaga station in Yakutia according to spectrophotometric data 47 events of the occurrence of red stable middle-latitudinal arcs (SAR-arcs) were recorded. On the basis of these data the latitudinal dynamics of SAR-arcs was studied depending on the local time and geomagnetic disturbance level. The uniform equatorial shift of SAR arcs in the night time is noticed, and a sharp increase of the speed of this motion can be caused by the nonstationary character of the magnetospheric activity

  1. Alaska Synthetic Aperture Radar (SAR) Facility science data processing architecture

    Science.gov (United States)

    Hilland, Jeffrey E.; Bicknell, Thomas; Miller, Carol L.

    1991-01-01

    The paper describes the architecture of the Alaska SAR Facility (ASF) at Fairbanks, being developed to generate science data products for supporting research in sea ice motion, ice classification, sea-ice-ocean interaction, glacier behavior, ocean waves, and hydrological and geological study areas. Special attention is given to the individual substructures of the ASF: the Receiving Ground Station (RGS), the SAR Processor System, and the Interactive Image Analysis System. The SAR data will be linked to the RGS by the ESA ERS-1 and ERS-2, the Japanese ERS-1, and the Canadian Radarsat.

  2. 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...

  3. LTE modem power consumption, SAR and RF signal strength emulation

    DEFF Research Database (Denmark)

    Musiige, Deogratius; Vincent, Laulagnet; Anton, François

    2012-01-01

    This paper presents a new methodology for emulating the LTE modem power consumption, emitted SAR and RF signal strength when transmitting an LTE signal. The inputs of the methodology are: modem logical/protocol commands, time advance, near-field specifier, and antenna characteristics. The power...... emulation model(s) are computed by a two layer 451 neural network based on physical power measurements. SAR is emulated by polynomial interpolation models based on FDTD simulations. The accuracies of the mathematical function approximations for the emulation models of power and SAR are 5.19% and 3...

  4. Blood donors--Serious adverse reactions (SAR) 2010-2014 EFS Châteauroux, France.

    Science.gov (United States)

    Riga, A; Sapey, T; Bacanu, M; Py, J-Y; Dehaut, F

    2015-06-01

    In 2013, the national French incidence of serious adverse reactions (SAR) was 155.7 per 100,000 donations and 82% of SAR were grade 2 (French classification of SAR related to blood donors) The purpose of our study was to describe the profile of blood donator candidate which had a SAR in our center. The study contains all the SAR superior to grade 1 occurred on the site EFS Châteauroux (site and mobile blood collection) from January 2010 to October 31, 2014. We analyzed 37 parameters from the e-fit files (e-site French blood vigilance) and In-log software. We identified 82 SAR for 72,553 blood donations (incidence: 113.02 SAR per 100,000 donations). Forty-one men and 41 women, middle age 39 years (18-66). Average height: 1.68 m (1.49-1.85); average weight: 68 kg (50-98); body mass index (kg/m(2)): 24,13(18.6-31.9). All donors were Caucasian and 30% unemployed. We found 74 vasovagal syncope (VVS), 5 hematomas, 2 arterial injuries and an adverse reaction to citrate. In 90%, the SAR was immediate and of grade 2 in 85% of cases. Thirty-seven percent of SAR were first donation in connection with whole blood in 87% of cases. Regarding the seniority of donors, the number of average donations (whole blood, plasma, platelets) was 16.5. An SAR determined the stop of blood donation in 65% of cases with nearly 80% stoppage if it was a first donation. Seventy-three percent of SAR as a VVS took place during blood collection or within 5 minutes following the end of the donation. Sixty-one percent were men. Forty-four percent of cases were a first donation and 83% occurred in mobile blood collection. Average age was 36 years. The result was a permanent stop of all type of donations in 76% of cases. Twenty-seven percent of SAR as a VVS took place beyond 5 minutes after the end of the donation. Seventy-five percent were women. Thirty percent of cases were a first donation and 95% of SAR occurred in mobile blood collection. Average age was 42 years. The result was a permanent stop of

  5. The planned Alaska SAR Facility - An overview

    Science.gov (United States)

    Carsey, Frank; Weeks, Wilford

    1987-01-01

    The Alaska SAR Facility (ASF) is described in an overview fashion. The facility consists of three major components, a Receiving Ground System, a SAR Processing System and an Analysis and Archiving System; the ASF Program also has a Science Working Team and the requisite management and operations systems. The ASF is now an approved and fully funded activity; detailed requirements and science background are presented for the facility to be implemented for data from the European ERS-1, the Japanese ERS-1 and Radarsat.

  6. 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. ...... 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)....

  7. 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...... mapping is complicated by an extreme topography leading to massive shadowing, foreshortening and layover. An artifact characterised by high cross-polarisation is observed behind many sharp mountain ridges. A multi-reflection hypothesis has been investigated without finding the ultimate proof...

  8. SAR processing in the cloud for oil detection in the Arctic

    Science.gov (United States)

    Garron, J.; Stoner, C.; Meyer, F. J.

    2016-12-01

    A new world of opportunity is being thawed from the ice of the Arctic, driven by decreased persistent Arctic sea-ice cover, increases in shipping, tourism, natural resource development. Tools that can automatically monitor key sea ice characteristics and potential oil spills are essential for safe passage in these changing waters. Synthetic aperture radar (SAR) data can be used to discriminate sea ice types and oil on the ocean surface and also for feature tracking. Additionally, SAR can image the earth through the night and most weather conditions. SAR data is volumetrically large and requires significant computing power to manipulate. Algorithms designed to identify key environmental features, like oil spills, in SAR imagery require secondary processing, and are computationally intensive, which can functionally limit their application in a real-time setting. Cloud processing is designed to manage big data and big data processing jobs by means of small cycles of off-site computations, eliminating up-front hardware costs. Pairing SAR data with cloud processing has allowed us to create and solidify a processing pipeline for SAR data products in the cloud to compare operational algorithms efficiency and effectiveness when run using an Alaska Satellite Facility (ASF) defined Amazon Machine Image (AMI). The products created from this secondary processing, were compared to determine which algorithm was most accurate in Arctic feature identification, and what operational conditions were required to produce the results on the ASF defined AMI. Results will be used to inform a series of recommendations to oil-spill response data managers and SAR users interested in expanding their analytical computing power.

  9. Automatic Detection and Positioning of Ground Control Points Using TerraSAR-X Multiaspect Acquisitions

    Science.gov (United States)

    Montazeri, Sina; Gisinger, Christoph; Eineder, Michael; Zhu, Xiao xiang

    2018-05-01

    Geodetic stereo Synthetic Aperture Radar (SAR) is capable of absolute three-dimensional localization of natural Persistent Scatterer (PS)s which allows for Ground Control Point (GCP) generation using only SAR data. The prerequisite for the method to achieve high precision results is the correct detection of common scatterers in SAR images acquired from different viewing geometries. In this contribution, we describe three strategies for automatic detection of identical targets in SAR images of urban areas taken from different orbit tracks. Moreover, a complete work-flow for automatic generation of large number of GCPs using SAR data is presented and its applicability is shown by exploiting TerraSAR-X (TS-X) high resolution spotlight images over the city of Oulu, Finland and a test site in Berlin, Germany.

  10. 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

  11. Wind class sampling of satellite SAR imagery for offshore wind resource mapping

    DEFF Research Database (Denmark)

    Badger, Merete; Badger, Jake; Nielsen, Morten

    2010-01-01

    developed for mesoscale modeling of wind resources. Its performance in connection with sampling of SAR scenes is tested against two sets of random SAR samples and meteorological observations at three sites in the North Sea during 2005–08. Predictions of the mean wind speed and the Weibull scale parameter......High-resolution wind fields retrieved from satellite synthetic aperture radar (SAR) imagery are combined for mapping of wind resources offshore where site measurements are costly and sparse. A new sampling strategy for the SAR scenes is introduced, based on a method for statistical......-dynamical downscaling of large-scale wind conditions using a set of wind classes that describe representative wind situations. One or more SAR scenes are then selected to represent each wind class and the classes are weighted according to their frequency of occurrence. The wind class methodology was originally...

  12. An Advanced Rotation Invariant Descriptor for SAR Image Registration

    Directory of Open Access Journals (Sweden)

    Yuming Xiang

    2017-07-01

    Full Text Available The Scale-Invariant Feature Transform (SIFT algorithm and its many variants have been widely used in Synthetic Aperture Radar (SAR image registration. The SIFT-like algorithms maintain rotation invariance by assigning a dominant orientation for each keypoint, while the calculation of dominant orientation is not robust due to the effect of speckle noise in SAR imagery. In this paper, we propose an advanced local descriptor for SAR image registration to achieve rotation invariance without assigning a dominant orientation. Based on the improved intensity orders, we first divide a circular neighborhood into several sub-regions. Second, rotation-invariant ratio orientation histograms of each sub-region are proposed by accumulating the ratio values of different directions in a rotation-invariant coordinate system. The proposed descriptor is composed of the concatenation of the histograms of each sub-region. In order to increase the distinctiveness of the proposed descriptor, multiple image neighborhoods are aggregated. Experimental results on several satellite SAR images have shown an improvement in the matching performance over other state-of-the-art algorithms.

  13. InSAR observations of active volcanoes in Latin America

    Science.gov (United States)

    Morales Rivera, A. M.; Chaussard, E.; Amelung, F.

    2012-12-01

    Over the last decade satellite-based interferometric synthetic aperture radar (InSAR) has developed into a well-known technique to gauge the status of active volcanoes. The InSAR technique can detect the ascent of magma to shallow levels of the volcanic plumbing system because new arriving magma pressurizes the system. This is likely associated with the inflation of the volcanic edifice and the surroundings. Although the potential of InSAR to detect magma migration is well known, the principal limitation was that only for few volcanoes frequent observations were acquired. The ALOS-1 satellite of the Japanese Aerospace Exploration Agency (JAXA) acquired a global L-band data set of 15-20 acquisitions during 2006-2011. Here we use ALOS InSAR and Small Baseline (SB) time-series methods for a ground deformation survey of Latin America with emphasis on the northern Andes. We present time-dependent ground deformation data for the volcanoes in Colombia, Ecuador and Peru and interpret the observations in terms of the dynamics of the volcanic systems.

  14. Emergency product generation for disaster management using RISAT and DMSAR quick look SAR processors

    Science.gov (United States)

    Desai, Nilesh; Sharma, Ritesh; Kumar, Saravana; Misra, Tapan; Gujraty, Virendra; Rana, SurinderSingh

    2006-12-01

    Since last few years, ISRO has embarked upon the development of two complex Synthetic Aperture Radar (SAR) missions, viz. Spaceborne Radar Imaging Satellite (RISAT) and Airborne SAR for Disaster Mangement (DMSAR), as a capacity building measure under country's Disaster Management Support (DMS) Program, for estimating the extent of damage over large areas (~75 Km) and also assess the effectiveness of the relief measures undertaken during natural disasters such as cyclones, epidemics, earthquakes, floods and landslides, forest fires, crop diseases etc. Synthetic Aperture Radar (SAR) has an unique role to play in mapping and monitoring of large areas affected by natural disasters especially floods, owing to its unique capability to see through clouds as well as all-weather imaging capability. The generation of SAR images with quick turn around time is very essential to meet the above DMS objectives. Thus the development of SAR Processors, for these two SAR systems poses considerable challenges and design efforts. Considering the growing user demand and inevitable necessity for a full-fledged high throughput processor, to process SAR data and generate image in real or near-real time, the design and development of a generic SAR Processor has been taken up and evolved, which will meet the SAR processing requirements for both Airborne and Spaceborne SAR systems. This hardware SAR processor is being built, to the extent possible, using only Commercial-Off-The-Shelf (COTS) DSP and other hardware plug-in modules on a Compact PCI (cPCI) platform. Thus, the major thrust has been on working out Multi-processor Digital Signal Processor (DSP) architecture and algorithm development and optimization rather than hardware design and fabrication. For DMSAR, this generic SAR Processor operates as a Quick Look SAR Processor (QLP) on-board the aircraft to produce real time full swath DMSAR images and as a ground based Near-Real Time high precision full swath Processor (NRTP). It will

  15. [SARS: a new emergency in the world health].

    Science.gov (United States)

    Calza, Leonardo; Manfredi, Roberto; Verucchi, Gabriella; Chiodo, Francesco

    2003-01-01

    The Severe Acute Respiratory Syndrome (SARS) is a new life-threatening respiratory disease which has its origins in Guangdong province, China, where the earliest known cases were identified in November 2002. Since then, probable cases of SARS have been reported in 30 countries and the current cumulative number of cases is 8,240 with 745 deaths and a global fatality rate of 9%. The most frequently involved areas include China, Hong Kong, Singapore, Canada, Vietnam and Philippines. Most cases of SARS to date have occurred in young adults and this disease appears to spread most commonly by close person-to-person contact, involving exposure to infectious droplets and body fluids. This transmission pattern generally involves household members, health care workers and international travellers, while a large and sudden cluster of almost simultaneous cases in an housing estate of Hong Kong has raised the possibility of transmission from an environmental source. The most common presenting symptoms are fever, malaise, non-productive cough and dyspnea, associated with pulmonary interstitial infiltrates on chest radiography. A novel coronavirus is associated with this outbreak, and the laboratory evidences indicate that this virus has an etiologic role in SARS, but the role of other concurrent viral agents (such as metapneumovirus) identified in these patients requires further investigation.

  16. Detection of moving humans in UHF wideband SAR

    Science.gov (United States)

    Sjögren, Thomas K.; Ulander, Lars M. H.; Frölind, Per-Olov; Gustavsson, Anders; Stenström, Gunnar; Jonsson, Tommy

    2014-06-01

    In this paper, experimental results for UHF wideband SAR imaging of humans on an open field and inside a forest is presented. The results show ability to detect the humans and suggest possible ways to improve the results. In the experiment, single channel wideband SAR mode of the UHF UWB system LORA developed by Swedish Defence Research Agency (FOI). The wideband SAR mode used in the experiment was from 220 to 450 MHz, thus with a fractional bandwidth of 0.68. Three humans walking and one stationary were available in the scene with one of the walking humans in the forest. The signature of the human in the forest appeared on the field, due to azimuth shift from the positive range speed component. One human on the field and the one in the forest had approximately the same speed and walking direction. The signatures in the SAR image were compared as a function of integration time based on focusing using the average relative speed of these given by GPS logs. A signal processing gain was obtained for the human in forest until approximately 15 s and 35 s for the human on the field. This difference is likely explained by uneven terrain and trees in the way, causing a non-straight walking path.

  17. Risk factors for SARS transmission from patients requiring intubation: a multicentre investigation in Toronto, Canada.

    Directory of Open Access Journals (Sweden)

    Janet Raboud

    Full Text Available BACKGROUND: In the 2003 Toronto SARS outbreak, SARS-CoV was transmitted in hospitals despite adherence to infection control procedures. Considerable controversy resulted regarding which procedures and behaviours were associated with the greatest risk of SARS-CoV transmission. METHODS: A retrospective cohort study was conducted to identify risk factors for transmission of SARS-CoV during intubation from laboratory confirmed SARS patients to HCWs involved in their care. All SARS patients requiring intubation during the Toronto outbreak were identified. All HCWs who provided care to intubated SARS patients during treatment or transportation and who entered a patient room or had direct patient contact from 24 hours before to 4 hours after intubation were eligible for this study. Data was collected on patients by chart review and on HCWs by interviewer-administered questionnaire. Generalized estimating equation (GEE logistic regression models and classification and regression trees (CART were used to identify risk factors for SARS transmission. RESULTS: 45 laboratory-confirmed intubated SARS patients were identified. Of the 697 HCWs involved in their care, 624 (90% participated in the study. SARS-CoV was transmitted to 26 HCWs from 7 patients; 21 HCWs were infected by 3 patients. In multivariate GEE logistic regression models, presence in the room during fiberoptic intubation (OR = 2.79, p = .004 or ECG (OR = 3.52, p = .002, unprotected eye contact with secretions (OR = 7.34, p = .001, patient APACHE II score > or = 20 (OR = 17.05, p = .009 and patient Pa0(2/Fi0(2 ratio < or = 59 (OR = 8.65, p = .001 were associated with increased risk of transmission of SARS-CoV. In CART analyses, the four covariates which explained the greatest amount of variation in SARS-CoV transmission were covariates representing individual patients. CONCLUSION: Close contact with the airway of severely ill patients and failure of infection control practices to prevent exposure

  18. Study on Zero-Doppler Centroid Control for GEO SAR Ground Observation

    Directory of Open Access Journals (Sweden)

    Yicheng Jiang

    2014-01-01

    Full Text Available In geosynchronous Earth orbit SAR (GEO SAR, Doppler centroid compensation is a key step for imaging process, which could be performed by the attitude steering of a satellite platform. However, this zero-Doppler centroid control method does not work well when the look angle of radar is out of an expected range. This paper primarily analyzes the Doppler properties of GEO SAR in the Earth rectangular coordinate. Then, according to the actual conditions of the GEO SAR ground observation, the effective range is presented by the minimum and maximum possible look angles which are directly related to the orbital parameters. Based on the vector analysis, a new approach for zero-Doppler centroid control in GEO SAR, performing the attitude steering by a combination of pitch and roll rotation, is put forward. This approach, considering the Earth’s rotation and elliptical orbit effects, can accurately reduce the residual Doppler centroid. All the simulation results verify the correctness of the range of look angle and the proposed steering method.

  19. 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.

  20. A MATCHING METHOD TO REDUCE THE INFLUENCE OF SAR GEOMETRIC DEFORMATION

    Directory of Open Access Journals (Sweden)

    C. Gao

    2018-04-01

    Full Text Available There are large geometrical deformations in SAR image, including foreshortening, layover, shade,which leads to SAR Image matching with low accuracy. Especially in complex terrain area, the control points are difficult to obtain, and the matching is difficult to achieve. Considering the impact of geometric distortions in SAR image pairs, a matching algorithm with a combination of speeded up robust features (SURF and summed of normalize cross correlation (SNCC was proposed, which can avoid the influence of SAR geometric deformation. Firstly, SURF algorithm was utilized to predict the search area. Then the matching point pairs was selected based on summed of normalized cross correlation. Finally, false match points were eliminated by the bidirectional consistency. SURF algorithm can control the range of matching points, and the matching points extracted from the deformation area are eliminated, and the matching points with stable and even distribution are obtained. The experimental results demonstrated that the proposed algorithm had high precision, and can effectively avoid the effect of geometric distortion on SAR image matching. Meet accuracy requirements of the block adjustment with sparse control points.

  1. Ionospheric errors compensation for ground deformation estimation with new generation SAR

    Science.gov (United States)

    Gomba, Giorgio; De Zan, Francesco; Rodriguez Gonzalez, Fernando

    2017-04-01

    Synthetic aperture radar (SAR) and interferometric SAR (InSAR) measurements are disturbed by the propagation velocity changes of microwaves that are caused by the high density of free electrons in the ionosphere. Most affected are low-frequency (L- or P-band) radars, as the recently launched ALOS-2 and the future Tandem-L and NISAR, although higher frequency (C- or X-band) systems, as the recently launched Sentinel-1, are not immune. Since the ionosphere is an obstacle to increasing the precision of new generation SAR systems needed to remotely measure the Earth's dynamic processes as for example ground deformation, it is necessary to estimate and compensate ionospheric propagation delays in SAR signals. In this work we discuss about the influence of the ionosphere on interferograms and the possible correction methods with relative accuracies. Consequently, the effect of ionospheric induced errors on ground deformation measurements prior and after ionosphere compensation will be analyzed. Examples will be presented of corrupted measurements of earthquakes and fault motion along with the corrected results using different methods.

  2. Estimating snow water equivalent (SWE) using interferometric synthetic aperture radar (InSAR)

    Science.gov (United States)

    Deeb, Elias J.

    Since the early 1990s, radar interferometry and interferometric synthetic aperture radar (InSAR) have been used extensively to measure changes in the Earth's surface. Previous research has presented theory for estimating snow properties, including potential for snow water equivalent (SWE) retrieval, using InSAR. The motivation behind using remote sensing to estimate SWE is to provide a more complete, continuous set of "observations" to assist in water management operations, climate change studies, and flood hazard forecasting. The research presented here primarily investigates the feasibility of using the InSAR technique at two different wavelengths (C-Band and L-Band) for SWE retrieval of dry snow within the Kuparuk watershed, North Slope, Alaska. Estimating snow distribution around meteorological towers on the coastal plain using a three-day repeat orbit of C-Band InSAR data was successful (Chapter 2). A longer wavelength L-band SAR is evaluated for SWE retrievals (Chapter 3) showing the ability to resolve larger snow accumulation events over a longer period of time. Comparisons of InSAR estimates and late spring manual sampling of SWE show a R2 = 0.61 when a coherence threshold is used to eliminate noisy SAR data. Qualitative comparisons with a high resolution digital elevation model (DEM) highlight areas of scour on windward slopes and areas of deposition on leeward slopes. When compared to a mid-winter transect of manually sampled snow depths, the InSAR SWE estimates yield a RMSE of 2.21cm when a bulk snow density is used and corrections for bracketing the satellite acquisition timing is performed. In an effort to validate the interaction of radar waves with a snowpack, the importance of the "dry snow" assumption for the estimation of SWE using InSAR is tested with an experiment in Little Cottonwood Canyon, Alta, Utah (Chapter 5). Snow wetness is shown to have a significant effect on the velocity of propagation within the snowpack. Despite the radar

  3. 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...

  4. Underwater Topography Detection in Coastal Areas Using Fully Polarimetric SAR Data

    Directory of Open Access Journals (Sweden)

    Xiaolin Bian

    2017-06-01

    Full Text Available Fully polarimetric synthetic aperture radar (SAR can provide detailed information on scattering mechanisms that could enable the target or structure to be identified. This paper presents a method to detect underwater topography in coastal areas using high resolution fully polarimetric SAR data, while less prior information is required. The method is based on the shoaling and refraction of long surface gravity waves as they propagate shoreward. First, the surface scattering component is obtained by polarization decomposition. Then, wave fields are retrieved from the two-dimensional (2D spectra by the Fast Fourier Transformation (FFT. Finally, shallow water depths are estimated from the dispersion relation. Applicability and effectiveness of the proposed methodology are tested by using C-band fine quad-polarization mode RADARSAT-2 SAR data over the near-shore area of the Hainan province, China. By comparing with the values from an official electronic navigational chart (ENC, the estimated water depths are in good agreement with them. The average relative error of the detected results from the scattering mechanisms based method and single polarization SAR data are 9.73% and 11.53% respectively. The validation results indicate that the scattering mechanisms based methodology is more effective than only using the single polarization SAR data for underwater topography detection, and will inspire further research on underwater topography detection with fully polarimetric SAR data.

  5. Stochastic modeling for time series InSAR: with emphasis on atmospheric effects

    Science.gov (United States)

    Cao, Yunmeng; Li, Zhiwei; Wei, Jianchao; Hu, Jun; Duan, Meng; Feng, Guangcai

    2018-02-01

    Despite the many applications of time series interferometric synthetic aperture radar (TS-InSAR) techniques in geophysical problems, error analysis and assessment have been largely overlooked. Tropospheric propagation error is still the dominant error source of InSAR observations. However, the spatiotemporal variation of atmospheric effects is seldom considered in the present standard TS-InSAR techniques, such as persistent scatterer interferometry and small baseline subset interferometry. The failure to consider the stochastic properties of atmospheric effects not only affects the accuracy of the estimators, but also makes it difficult to assess the uncertainty of the final geophysical results. To address this issue, this paper proposes a network-based variance-covariance estimation method to model the spatiotemporal variation of tropospheric signals, and to estimate the temporal variance-covariance matrix of TS-InSAR observations. The constructed stochastic model is then incorporated into the TS-InSAR estimators both for parameters (e.g., deformation velocity, topography residual) estimation and uncertainty assessment. It is an incremental and positive improvement to the traditional weighted least squares methods to solve the multitemporal InSAR time series. The performance of the proposed method is validated by using both simulated and real datasets.

  6. ALGORITHM OF SAR SATELLITE ATTITUDE MEASUREMENT USING GPS AIDED BY KINEMATIC VECTOR

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, in order to improve the accuracy of the Synthetic Aperture Radar (SAR)satellite attitude using Global Positioning System (GPS) wide-band carrier phase, the SAR satellite attitude kinematic vector and Kalman filter are introduced. Introducing the state variable function of GPS attitude determination algorithm in SAR satellite by means of kinematic vector and describing the observation function by the GPS wide-band carrier phase, the paper uses the Kalman filter algorithm to obtian the attitude variables of SAR satellite. Compared the simulation results of Kalman filter algorithm with the least square algorithm and explicit solution, it is indicated that the Kalman filter algorithm is the best.

  7. Measurement of Subsidence in the Yangbajain Geothermal Fields from TerraSAR-X

    Science.gov (United States)

    Li, Yongsheng; Zhang, Jingfa; Li, Zhenhong

    2016-08-01

    Yangbajain contains the largest geothermal energy power station in China. Geothermal explorations in Yangbajain first started in 1976, and two plants were subsequently built in 1981 and 1986. A large amount of geothermal fluids have been extracted since then, leading to considerable surface subsidence around the geothermal fields. In this paper, InSAR time series analysis is applied to map the subsidence of the Yangbajain geothermal fields during the period from December 2011 to November 2012 using 16 senses of TerraSAR-X stripmap SAR images. Due to its high resolution and short repeat cycle, TerraSAR-X provides detailed surface deformation information at the Yangbajain geothermal fields.

  8. SAR image dataset of military ground targets with multiple poses for ATR

    Science.gov (United States)

    Belloni, Carole; Balleri, Alessio; Aouf, Nabil; Merlet, Thomas; Le Caillec, Jean-Marc

    2017-10-01

    Automatic Target Recognition (ATR) is the task of automatically detecting and classifying targets. Recognition using Synthetic Aperture Radar (SAR) images is interesting because SAR images can be acquired at night and under any weather conditions, whereas optical sensors operating in the visible band do not have this capability. Existing SAR ATR algorithms have mostly been evaluated using the MSTAR dataset.1 The problem with the MSTAR is that some of the proposed ATR methods have shown good classification performance even when targets were hidden,2 suggesting the presence of a bias in the dataset. Evaluations of SAR ATR techniques are currently challenging due to the lack of publicly available data in the SAR domain. In this paper, we present a high resolution SAR dataset consisting of images of a set of ground military target models taken at various aspect angles, The dataset can be used for a fair evaluation and comparison of SAR ATR algorithms. We applied the Inverse Synthetic Aperture Radar (ISAR) technique to echoes from targets rotating on a turntable and illuminated with a stepped frequency waveform. The targets in the database consist of four variants of two 1.7m-long models of T-64 and T-72 tanks. The gun, the turret position and the depression angle are varied to form 26 different sequences of images. The emitted signal spanned the frequency range from 13 GHz to 18 GHz to achieve a bandwidth of 5 GHz sampled with 4001 frequency points. The resolution obtained with respect to the size of the model targets is comparable to typical values obtained using SAR airborne systems. Single polarized images (Horizontal-Horizontal) are generated using the backprojection algorithm.3 A total of 1480 images are produced using a 20° integration angle. The images in the dataset are organized in a suggested training and testing set to facilitate a standard evaluation of SAR ATR algorithms.

  9. Utility of Characterizing and Monitoring Suspected Underground Nuclear Sites with VideoSAR

    Science.gov (United States)

    Dauphin, S. M.; Yocky, D. A.; Riley, R.; Calloway, T. M.; Wahl, D. E.

    2016-12-01

    Sandia National Laboratories proposed using airborne synthetic aperture RADAR (SAR) collected in VideoSAR mode to characterize the Underground Nuclear Explosion Signature Experiment (UNESE) test bed site at the Nevada National Security Site (NNSS). The SNL SAR collected airborne, Ku-band (16.8 GHz center frequency), 0.2032 meter ground resolution over NNSS in August 2014 and X-band (9.6 GHz), 0.1016 meter ground resolution fully-polarimetric SAR in April 2015. This paper reports the findings of processing and exploiting VideoSAR for creating digital elevation maps, detecting cultural artifacts and exploiting full-circle polarimetric signatures. VideoSAR collects a continuous circle of phase history data, therefore, imagery can be formed over the 360-degrees of the site. Since the Ku-band VideoSAR had two antennas suitable for interferometric digital elevation mapping (DEM), DEMs could be generated over numerous aspect angles, filling in holes created by targets with height by imaging from all sides. Also, since the X-band VideoSAR was fully-polarimetric, scattering signatures could be gleaned from all angles also. Both of these collections can be used to find man-made objects and changes in elevation that might indicate testing activities. VideoSAR provides a unique, coherent measure of ground objects allowing one to create accurate DEMS, locate man-made objects, and identify scattering signatures via polarimetric exploitation. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. The authors would like to thank the National Nuclear Security Administration, Defense Nuclear Nonproliferation Research and Development, for sponsoring this work. We would also like to thank the Underground Nuclear Explosion Signatures Experiment team, a multi

  10. SAR Data Fusion Imaging Method Oriented to Target Feature Extraction

    Directory of Open Access Journals (Sweden)

    Yang Wei

    2015-02-01

    Full Text Available To deal with the difficulty for target outlines extracting precisely due to neglect of target scattering characteristic variation during the processing of high-resolution space-borne SAR data, a novel fusion imaging method is proposed oriented to target feature extraction. Firstly, several important aspects that affect target feature extraction and SAR image quality are analyzed, including curved orbit, stop-and-go approximation, atmospheric delay, and high-order residual phase error. Furthermore, the corresponding compensation methods are addressed as well. Based on the analysis, the mathematical model of SAR echo combined with target space-time spectrum is established for explaining the space-time-frequency change rule of target scattering characteristic. Moreover, a fusion imaging strategy and method under high-resolution and ultra-large observation angle range conditions are put forward to improve SAR quality by fusion processing in range-doppler and image domain. Finally, simulations based on typical military targets are used to verify the effectiveness of the fusion imaging method.

  11. Feature extraction for SAR target recognition based on supervised manifold learning

    International Nuclear Information System (INIS)

    Du, C; Zhou, S; Sun, J; Zhao, J

    2014-01-01

    On the basis of manifold learning theory, a new feature extraction method for Synthetic aperture radar (SAR) target recognition is proposed. First, the proposed algorithm estimates the within-class and between-class local neighbourhood surrounding each SAR sample. After computing the local tangent space for each neighbourhood, the proposed algorithm seeks for the optimal projecting matrix by preserving the local within-class property and simultaneously maximizing the local between-class separability. The use of uncorrelated constraint can also enhance the discriminating power of the optimal projecting matrix. Finally, the nearest neighbour classifier is applied to recognize SAR targets in the projected feature subspace. Experimental results on MSTAR datasets demonstrate that the proposed method can provide a higher recognition rate than traditional feature extraction algorithms in SAR target recognition

  12. Staphylococcus aureus sarA regulates inflammation and colonization during central nervous system biofilm formation.

    Directory of Open Access Journals (Sweden)

    Jessica N Snowden

    Full Text Available Infection is a frequent and serious complication following the treatment of hydrocephalus with CSF shunts, with limited therapeutic options because of biofilm formation along the catheter surface. Here we evaluated the possibility that the sarA regulatory locus engenders S. aureus more resistant to immune recognition in the central nervous system (CNS based on its reported ability to regulate biofilm formation. We utilized our established model of CNS catheter-associated infection, similar to CSF shunt infections seen in humans, to compare the kinetics of bacterial titers, cytokine production and inflammatory cell influx elicited by wild type S. aureus versus an isogenic sarA mutant. The sarA mutant was more rapidly cleared from infected catheters compared to its isogenic wild type strain. Consistent with this finding, several pro-inflammatory cytokines and chemokines, including IL-17, CXCL1, and IL-1β were significantly increased in the brain following infection with the sarA mutant versus wild type S. aureus, in agreement with the fact that the sarA mutant displayed impaired biofilm growth and favored a planktonic state. Neutrophil influx into the infected hemisphere was also increased in the animals infected with the sarA mutant compared to wild type bacteria. These changes were not attributable to extracellular protease activity, which is increased in the context of SarA mutation, since similar responses were observed between sarA and a sarA/protease mutant. Overall, these results demonstrate that sarA plays an important role in attenuating the inflammatory response during staphylococcal biofilm infection in the CNS via a mechanism that remains to be determined.

  13. Polarimetric SAR interferometry applied to land ice: modeling

    DEFF Research Database (Denmark)

    Dall, Jørgen; Papathanassiou, Konstantinos; Skriver, Henning

    2004-01-01

    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...... 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...

  14. Acute and chronic toxicity of uranium compounds to Ceriodaphnia-Daphnia dubia

    International Nuclear Information System (INIS)

    Pickett, J.B.; Specht, W.L.; Keyes, J.L.

    1993-01-01

    A study to determine the acute and chronic toxicity of uranyl nitrate, hydrogen uranyl phosphate, and uranium dioxide to the organism Ceriodaphnia dubia was conducted. The toxicity tests were conducted by two independent environmental consulting laboratories. Part of the emphasis for this determination was based on concerns expressed by SCDHEC, which was concerned that a safety factor of 100 must be applied to the previous 1986 acute toxicity result of 0.22 mg/L for Daphnia pulex, This would have resulted in the LETF release limits being based on an instream concentration of 0.0022 mg/L uranium. The NPDES Permit renewal application to SCDHEC utilized the results of this study and recommended that the LETF release limit for uranium be based an instream concentration of 0.004 mg/L uranium. This is based on the fact that the uranium releases from the M-Area LETF will be in the hydrogen uranyl phosphate form, or a uranyl phosphate complex at the pH (6--10) of the Liquid Effluent Treatment Facility effluent stream, and at the pH of the receiving stream (5.5 to 7.0). Based on the chronic toxicity of hydrogen uranyl phosphate, a lower uranium concentration limit for the Liquid Effluent Treatment Facility outfall vs. the existing NPDES permit was recommended: The current NPDES permit ''Guideline'' for uranium at outfall M-004 is 0.500 mg/L average and 1.0 mg/L maximum, at a design flowrate of 60 gpm. It was recommended that the uranium concentration at the M-004 outfall be reduced to 0.28 mg/L average, and 0.56 mg/L, maximum, and to reduce the design flowrate to 30 gpm. The 0.28 mg/L concentration will provide an instream concentration of 0.004 mg/L uranium. The 0.28 mg/L concentration at M-004 is based on the combined flows from A-014, A-015, and A-011 outfalls (since 1985) of 1840 gpm (2.65 MGD) and was the flow rate which was utilized in the 1988 NPDES permit renewal application

  15. Application of SAR interferometry to low-rate crustal deformation fields

    Science.gov (United States)

    Vincent, Paul

    Differential SAR interferometry is applied to the study of low-rate interseismic crustal deformation fields along three regions of the San Adreas fault system: Salton Sea (southernmost region), Pinto Mountain fault (south-central region), and San Francisco Bay (northern region). New techniques are developed to analyze and model these low-rate deformation fields including constrained horizontal-vertical component deconvolution, deformation phase pattern analysis and strain field evolution modeling. Several new active faults were discovered as well as unmeasured activity on existing faults in the process of this SAR interferometry study. The feasibility and limitations of InSAR as a tool to study low-rate deformation fields is also addressed.

  16. Yeast based small molecule screen for inhibitors of SARS-CoV.

    Directory of Open Access Journals (Sweden)

    Matthew Frieman

    Full Text Available Severe acute respiratory coronavirus (SARS-CoV emerged in 2002, resulting in roughly 8000 cases worldwide and 10% mortality. The animal reservoirs for SARS-CoV precursors still exist and the likelihood of future outbreaks in the human population is high. The SARS-CoV papain-like protease (PLP is an attractive target for pharmaceutical development because it is essential for virus replication and is conserved among human coronaviruses. A yeast-based assay was established for PLP activity that relies on the ability of PLP to induce a pronounced slow-growth phenotype when expressed in S. cerevisiae. Induction of the slow-growth phenotype was shown to take place over a 60-hour time course, providing the basis for conducting a screen for small molecules that restore growth by inhibiting the function of PLP. Five chemical suppressors of the slow-growth phenotype were identified from the 2000 member NIH Diversity Set library. One of these, NSC158362, potently inhibited SARS-CoV replication in cell culture without toxic effects on cells, and it specifically inhibited SARS-CoV replication but not influenza virus replication. The effect of NSC158362 on PLP protease, deubiquitinase and anti-interferon activities was investigated but the compound did not alter these activities. Another suppressor, NSC158011, demonstrated the ability to inhibit PLP protease activity in a cell-based assay. The identification of these inhibitors demonstrated a strong functional connection between the PLP-based yeast assay, the inhibitory compounds, and SARS-CoV biology. Furthermore the data with NSC158362 suggest a novel mechanism for inhibition of SARS-CoV replication that may involve an unknown activity of PLP, or alternatively a direct effect on a cellular target that modifies or bypasses PLP function in yeast and mammalian cells.

  17. Multiple Input - Multiple Output (MIMO) SAR

    Data.gov (United States)

    National Aeronautics and Space Administration — This effort will research and implement advanced Multiple-Input Multiple-Output (MIMO) Synthetic Aperture Radar (SAR) techniques which have the potential to improve...

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

    Directory of Open Access Journals (Sweden)

    Fábio Guimarães Gonçalves

    2007-06-01

    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 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.

  19. 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.

  20. SAR image classification based on CNN in real and simulation datasets

    Science.gov (United States)

    Peng, Lijiang; Liu, Ming; Liu, Xiaohua; Dong, Liquan; Hui, Mei; Zhao, Yuejin

    2018-04-01

    Convolution neural network (CNN) has made great success in image classification tasks. Even in the field of synthetic aperture radar automatic target recognition (SAR-ATR), state-of-art results has been obtained by learning deep representation of features on the MSTAR benchmark. However, the raw data of MSTAR have shortcomings in training a SAR-ATR model because of high similarity in background among the SAR images of each kind. This indicates that the CNN would learn the hierarchies of features of backgrounds as well as the targets. To validate the influence of the background, some other SAR images datasets have been made which contains the simulation SAR images of 10 manufactured targets such as tank and fighter aircraft, and the backgrounds of simulation SAR images are sampled from the whole original MSTAR data. The simulation datasets contain the dataset that the backgrounds of each kind images correspond to the one kind of backgrounds of MSTAR targets or clutters and the dataset that each image shares the random background of whole MSTAR targets or clutters. In addition, mixed datasets of MSTAR and simulation datasets had been made to use in the experiments. The CNN architecture proposed in this paper are trained on all datasets mentioned above. The experimental results shows that the architecture can get high performances on all datasets even the backgrounds of the images are miscellaneous, which indicates the architecture can learn a good representation of the targets even though the drastic changes on background.

  1. Air pollution and case fatality of SARS in the People's Republic of China: an ecologic study

    Directory of Open Access Journals (Sweden)

    Yu Shun-Zhang

    2003-11-01

    Full Text Available Abstract Background Severe acute respiratory syndrome (SARS has claimed 349 lives with 5,327 probable cases reported in mainland China since November 2002. SARS case fatality has varied across geographical areas, which might be partially explained by air pollution level. Methods Publicly accessible data on SARS morbidity and mortality were utilized in the data analysis. Air pollution was evaluated by air pollution index (API derived from the concentrations of particulate matter, sulfur dioxide, nitrogen dioxide, carbon monoxide and ground-level ozone. Ecologic analysis was conducted to explore the association and correlation between air pollution and SARS case fatality via model fitting. Partially ecologic studies were performed to assess the effects of long-term and short-term exposures on the risk of dying from SARS. Results Ecologic analysis conducted among 5 regions with 100 or more SARS cases showed that case fatality rate increased with the increment of API (case fatality = - 0.063 + 0.001 * API. Partially ecologic study based on short-term exposure demonstrated that SARS patients from regions with moderate APIs had an 84% increased risk of dying from SARS compared to those from regions with low APIs (RR = 1.84, 95% CI: 1.41–2.40. Similarly, SARS patients from regions with high APIs were twice as likely to die from SARS compared to those from regions with low APIs. (RR = 2.18, 95% CI: 1.31–3.65. Partially ecologic analysis based on long-term exposure to ambient air pollution showed the similar association. Conclusion Our studies demonstrated a positive association between air pollution and SARS case fatality in Chinese population by utilizing publicly accessible data on SARS statistics and air pollution indices. Although ecologic fallacy and uncontrolled confounding effect might have biased the results, the possibility of a detrimental effect of air pollution on the prognosis of SARS patients deserves further investigation.

  2. Beyond PSInSAR: the SQUEESAR Approach

    Science.gov (United States)

    Ferretti, A.; Novali, F.; Fumagalli, A.; Prati, C.; Rocca, F.; Rucci, A.

    2009-12-01

    After a decade since the first results on ERS data, Permanent Scatterer (PS) InSAR has become an operational technology for detecting and monitoring slow surface deformation phenomena such as subsidence and uplift, landslides, seismic fault creeping, volcanic inflation, etc. Processing procedures have been continuously updated, but the core of the algorithm has not been changed significantly. As well known, in PSInSAR, the main target is the identification of individual pixels that exhibit a “PS behavior”, i.e. they are only slightly affected by both temporal and geometrical decorrelation. Typically, these scatterers correspond to man-made objects, but PS have been identified also in non-urban areas, where exposed rocks or outcrops can indeed create good radar benchmarks and enable high-quality displacement measurements. Contrary to interferogram stacking techniques, PS analyses are carried out on a pixel-by-pixel basis, with no filtering of the interferograms, in order to preserve phase values from possible incoherent clutter surrounding good radar targets. In fact, any filtering process implies a spatial smoothing of the data that could compromise - rather than improve - phase coherence, at least for isolated PS. Although the PS approach usually allows one to retrieve high quality deformation measurements on a sparse grid of good radar targets, in some datasets it is quite evident how the number of pixels where some information can be extracted could be significantly increased by relaxing the hypothesis on target coherence and searching for pixels where the coherence level is high enough at least in some interferograms of the data-stack, not necessarily all. The idea of computing a “coherence matrix” for each pixel of the area of interest have been already proposed in previous papers, together with a statistical estimation of some physical parameters of interest (e.g. the average displacement rate) based on the covariance matrix. In past publications

  3. Comparisons of Circular Transmit and Linear Receive Compact Polarimetric SAR Features for Oil Slicks Discrimination

    Directory of Open Access Journals (Sweden)

    Yu Li

    2015-01-01

    Full Text Available Compact polarimetric (CP synthetic aperture radar (SAR has proven its potential in distinguishing oil slicks and look-alikes. Polarimetric information can be retrieved directly from scattering vector or from reconstructed pseudo-Quad-Pol covariance matrix of CP SAR data. In this paper, we analysed features from Circular Transmit and Linear Receive (CTLR CP SAR data that are derived by taking both of these two methods. K-means clustering followed by accuracy assessment was also implemented for performance evaluation. Through experiments that were conducted based on L-band UAVSAR fully polarimetric data, it was found that optimum extraction methods varied for different features. The histogram analysis and segmentation results also demonstrated the comparable performance of CP SAR features in distinguishing different damping properties within oil slicks. This study proposed a framework of statistically analyzing polarimetric SAR (Pol-SAR features and provided guidelines for determining optimum feature extraction methods from CP SAR data and for marine oil-spills detection and classification.

  4. Analysis of the Effect of Radio Frequency Interference on Repeat Track Airborne InSAR System

    Directory of Open Access Journals (Sweden)

    Ding Bin

    2012-03-01

    Full Text Available The SAR system operating at low frequency is susceptible to Radio Frequency Interference (RFI from television station, radio station, and some other civil electronic facilities. The presence of RFI degrades the SAR image quality, and obscures the targets in the scene. Furthermore, RFI can cause interferometric phase error in repeat track InSAR system. In order to analyze the effect of RFI on interferometric phase of InSAR, real measured RFI signal are added on cone simulated SAR echoes. The imaging and interferometric processing results of both the RFI-contaminated and raw data are given. The effect of real measured RFI signal on repeat track InSAR system is analyzed. Finally, the imaging and interferometric processing results of both with and without RFI suppressed of the P band airborne repeat track InSAR real data are presented, which demonstrates the efficiency of the RFI suppression method in terms of decreasing the interferometric phase errors caused by RFI.

  5. 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.

  6. Monitoring of Land-Surface Deformation in the Karamay Oilfield, Xinjiang, China, Using SAR Interferometry

    Directory of Open Access Journals (Sweden)

    Yusupujiang Aimaiti

    2017-07-01

    Full Text Available Synthetic Aperture Radar (SAR interferometry is a technique that provides high-resolution measurements of the ground displacement associated with various geophysical processes. To investigate the land-surface deformation in Karamay, a typical oil-producing city in the Xinjiang Uyghur Autonomous Region, China, Advanced Land Observing Satellite (ALOS Phased Array L-band Synthetic Aperture Radar (PALSAR data were acquired for the period from 2007 to 2009, and a two-pass differential SAR interferometry (D-InSAR process was applied. The experimental results showed that two sites in the north-eastern part of the city exhibit a clear indication of land deformation. For a further evaluation of the D-InSAR result, the Persistent Scatterer (PS and Small Baseline Subset (SBAS-InSAR techniques were applied for 21 time series Environmental Satellite (ENVISAT C-band Advanced Synthetic Aperture Radar (ASAR data from 2003 to 2010. The comparison between the D-InSAR and SBAS-InSAR measurements had better agreement than that from the PS-InSAR measurement. The maximum deformation rate attributed to subsurface water injection for the period from 2003 to 2010 was up to approximately 33 mm/year in the line of sight (LOS direction. The interferometric phase change from November 2007 to June 2010 showed a clear deformation pattern, and the rebound center has been expanding in scale and increasing in quantity.

  7. Azimuth Ambiguities Removal in Littoral Zones Based on Multi-Temporal SAR Images

    Directory of Open Access Journals (Sweden)

    Xiangguang Leng

    2017-08-01

    Full Text Available Synthetic aperture radar (SAR is one of the most important techniques for ocean monitoring. Azimuth ambiguities are a real problem in SAR images today, which can cause performance degradation in SAR ocean applications. In particular, littoral zones can be strongly affected by land-based sources, whereas they are usually regions of interest (ROI. Given the presence of complexity and diversity in littoral zones, azimuth ambiguities removal is a tough problem. As SAR sensors can have a repeat cycle, multi-temporal SAR images provide new insight into this problem. A method for azimuth ambiguities removal in littoral zones based on multi-temporal SAR images is proposed in this paper. The proposed processing chain includes co-registration, local correlation, binarization, masking, and restoration steps. It is designed to remove azimuth ambiguities caused by fixed land-based sources. The idea underlying the proposed method is that sea surface is dynamic, whereas azimuth ambiguities caused by land-based sources are constant. Thus, the temporal consistence of azimuth ambiguities is higher than sea clutter. It opens up the possibilities to use multi-temporal SAR data to remove azimuth ambiguities. The design of the method and the experimental procedure are based on images from the Sentinel data hub of Europe Space Agency (ESA. Both Interferometric Wide Swath (IW and Stripmap (SM mode images are taken into account to validate the proposed method. This paper also presents two RGB composition methods for better azimuth ambiguities visualization. Experimental results show that the proposed method can remove azimuth ambiguities in littoral zones effectively.

  8. Mechanisms of SAR Imaging of Shallow Water Topography of the Subei Bank

    Directory of Open Access Journals (Sweden)

    Shuangshang Zhang

    2017-11-01

    Full Text Available In this study, the C-band radar backscatter features of the shallow water topography of Subei Bank in the Southern Yellow Sea are statistically investigated using 25 ENVISAT (Environmental Satellite ASAR (advanced synthetic aperture radar and ERS-2 (European Remote-Sensing Satellite-2 SAR images acquired between 2006 and 2010. Different bathymetric features are found on SAR imagery under different sea states. Under low to moderate wind speeds (3.1~6.3 m/s, the wide bright patterns with an average width of 6 km are shown and correspond to sea surface imprints of tidal channels formed by two adjacent sand ridges, while the sand ridges appear as narrower (only 1 km wide, fingerlike, quasi-linear features on SAR imagery in high winds (5.4~13.9 m/s. Two possible SAR imaging mechanisms of coastal bathymetry are proposed in the case where the flow is parallel to the major axes of tidal channels or sand ridges. When the surface Ekman current is opposite to the mean tidal flow, two vortexes will converge at the central line of the tidal channel in the upper layer and form a convergent zone over the sea surface. Thus, the tidal channels are shown as wide and bright stripes on SAR imagery. For the SAR imaging of sand ridges, all the SAR images were acquired at low tidal levels. In this case, the ocean surface waves are possibly broken up under strong winds when propagating from deep water to the shallower water, which leads to an increase of surface roughness over the sand ridges.

  9. Object Georeferencing in UAV-Based SAR Terrain Images

    Directory of Open Access Journals (Sweden)

    Łabowski Michał

    2016-12-01

    Full Text Available Synthetic aperture radars (SAR allow to obtain high resolution terrain images comparable with the resolution of optical methods. Radar imaging is independent on the weather conditions and the daylight. The process of analysis of the SAR images consists primarily of identifying of interesting objects. The ability to determine their geographical coordinates can increase usability of the solution from a user point of view. The paper presents a georeferencing method of the radar terrain images. The presented images were obtained from the SAR system installed on board an Unmanned Aerial Vehicle (UAV. The system was developed within a project under acronym WATSAR realized by the Military University of Technology and WB Electronics S.A. The source of the navigation data was an INS/GNSS system integrated by the Kalman filter with a feed-backward correction loop. The paper presents the terrain images obtained during flight tests and results of selected objects georeferencing with an assessment of the accuracy of the method.

  10. MM wave SAR sensor design: Concept for an airborne low level reconnaissance system

    Science.gov (United States)

    Boesswetter, C.

    1986-07-01

    The basic system design considerations for a high resolution SAR system operating at 35 GHz or 94 GHz are given. First it is shown that only the focussed SAR concept in the side looking configuration matches the requirements and constraints. After definition of illumination geometry and airborne modes the fundamental SAR parameters in range and azimuth direction are derived. A review of the performance parameters of some critical mm wave components (coherent pulsed transmitters, front ends, antennas) establish the basis for further analysis. The power and contrast budget in the processed SAR image shows the feasibility of a 35/94 GHz SAR sensor design. The discussion of the resulting system parameters points out that this unusual system design implies both benefits and new risk areas. One of the benefits besides the compactness of sensor hardware turns out to be the short synthetic aperture length simplifying the design of the digital SAR processor, preferably operating in real time. A possible architecture based on current state-of-the-art correlator hardware is shown. One of the potential risk areas in achieving high resolution SAR imagery in the mm wave frequency band is motion compensation. However, it is shown that the short range and short synthetic aperture lengths ease the problem so that correction of motion induced phase errors and thus focussed synthetic aperture processing should be possible.

  11. Multi-Frequency Polarimetric SAR Classification Based on Riemannian Manifold and Simultaneous Sparse Representation

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2015-07-01

    Full Text Available Normally, polarimetric SAR classification is a high-dimensional nonlinear mapping problem. In the realm of pattern recognition, sparse representation is a very efficacious and powerful approach. As classical descriptors of polarimetric SAR, covariance and coherency matrices are Hermitian semidefinite and form a Riemannian manifold. Conventional Euclidean metrics are not suitable for a Riemannian manifold, and hence, normal sparse representation classification cannot be applied to polarimetric SAR directly. This paper proposes a new land cover classification approach for polarimetric SAR. There are two principal novelties in this paper. First, a Stein kernel on a Riemannian manifold instead of Euclidean metrics, combined with sparse representation, is employed for polarimetric SAR land cover classification. This approach is named Stein-sparse representation-based classification (SRC. Second, using simultaneous sparse representation and reasonable assumptions of the correlation of representation among different frequency bands, Stein-SRC is generalized to simultaneous Stein-SRC for multi-frequency polarimetric SAR classification. These classifiers are assessed using polarimetric SAR images from the Airborne Synthetic Aperture Radar (AIRSAR sensor of the Jet Propulsion Laboratory (JPL and the Electromagnetics Institute Synthetic Aperture Radar (EMISAR sensor of the Technical University of Denmark (DTU. Experiments on single-band and multi-band data both show that these approaches acquire more accurate classification results in comparison to many conventional and advanced classifiers.

  12. 3D Tomographic SAR Imaging in Densely Vegetated Mountainous Rural Areas in China and Sweden

    Science.gov (United States)

    Feng, L.; Muller, J. P., , Prof

    2017-12-01

    3D SAR Tomography (TomoSAR) and 4D SAR Differential Tomography (Diff-TomoSAR) exploit multi-baseline SAR data stacks to create an important new innovation of SAR Interferometry, to unscramble complex scenes with multiple scatterers mapped into the same SAR cell. In addition to this 3-D shape reconstruction and deformation solution in complex urban/infrastructure areas, and recent cryospheric ice investigations, emerging tomographic remote sensing applications include forest applications, e.g. tree height and biomass estimation, sub-canopy topographic mapping, and even search, rescue and surveillance. However, these scenes are characterized by temporal decorrelation of scatterers, orbital, tropospheric and ionospheric phase distortion and an open issue regarding possible height blurring and accuracy losses for TomoSAR applications particularly in densely vegetated mountainous rural areas. Thus, it is important to develop solutions for temporal decorrelation, orbital, tropospheric and ionospheric phase distortion.We report here on 3D imaging (especially in vertical layers) over densely vegetated mountainous rural areas using 3-D SAR imaging (SAR tomography) derived from data stacks of X-band COSMO-SkyMed Spotlight and L band ALOS-1 PALSAR data stacks over Dujiangyan Dam, Sichuan, China and L and P band airborne SAR data (BioSAR 2008 - ESA) in the Krycklan river catchment, Northern Sweden. The new TanDEM-X 12m DEM is used to assist co - registration of all the data stacks over China first. Then, atmospheric correction is being assessed using weather model data such as ERA-I, MERRA, MERRA-2, WRF; linear phase-topography correction and MODIS spectrometer correction will be compared and ionospheric correction methods are discussed to remove tropospheric and ionospheric delay. Then the new TomoSAR method with the TanDEM-X 12m DEM is described to obtain the number of scatterers inside each pixel, the scattering amplitude and phase of each scatterer and finally extract

  13. Urban Monitoring Based on SENTINEL-1 Data Using Permanent Scatterer Interferometry and SAR Tomography

    Science.gov (United States)

    Crosetto, M.; Budillon, A.; Johnsy, A.; Schirinzi, G.; Devanthéry, N.; Monserrat, O.; Cuevas-González, M.

    2018-04-01

    A lot of research and development has been devoted to the exploitation of satellite SAR images for deformation measurement and monitoring purposes since Differential Interferometric Synthetic Apertura Radar (InSAR) was first described in 1989. In this work, we consider two main classes of advanced DInSAR techniques: Persistent Scatterer Interferometry and Tomographic SAR. Both techniques make use of multiple SAR images acquired over the same site and advanced procedures to separate the deformation component from the other phase components, such as the residual topographic component, the atmospheric component, the thermal expansion component and the phase noise. TomoSAR offers the advantage of detecting either single scatterers presenting stable proprieties over time (Persistent Scatterers) and multiple scatterers interfering within the same range-azimuth resolution cell, a significant improvement for urban areas monitoring. This paper addresses a preliminary inter-comparison of the results of both techniques, for a test site located in the metropolitan area of Barcelona (Spain), where interferometric Sentinel-1 data were analysed.

  14. The Singaporean response to the SARS outbreak: knowledge sufficiency versus public trust.

    Science.gov (United States)

    Deurenberg-Yap, M; Foo, L L; Low, Y Y; Chan, S P; Vijaya, K; Lee, M

    2005-12-01

    During the outbreak of severe acute respiratory syndrome (SARS) in Singapore from 1 March to 11 May 2003, various national prevention and control measures were undertaken to control and eliminate the transmission of the infection. During the initial period of the epidemic, public communication was effected through press releases and media coverage of the epidemic. About a month into the epidemic, a public education campaign was mounted to educate Singaporeans on SARS and adoption of appropriate behaviours to prevent the spread of the disease. A survey was conducted in late April 2003 to assess Singaporeans' knowledge about SARS and infection control measures, and their concerns and anxiety in relation to the outbreak. The survey also sought to assess their confidence in the ability of various institutions to deal with SARS and their opinion on the seemingly tough measures enforced. The study involved 853 adults selected from a telephone-sampling frame. Stratified sampling was used to ensure adequate representation from major ethnic groups and age groups. The study showed that the overall knowledge about SARS and control measures undertaken was low (mean per cent score of 24.5 +/- 8.9%). While 82% of respondents expressed confidence in measures undertaken by Tan Tock Seng Hospital (the hospital designated to manage SARS), only 36% had confidence in nursing homes. However, >80% of the public agreed that the preventive and control measures instituted were appropriate. Despite the low knowledge score, the overall mean satisfaction score of the government's response to SARS was 4.47 (out of possible highest score of 5.00), with >93% of adult Singaporeans indicating that they were satisfied or very satisfied with the government's response to SARS. Generally, Singaporeans had a high level of public trust (satisfaction with government, confidence in institutions, deeming government measures appropriate), scoring 11.4 out of possible maximum of 14. The disparity between low

  15. SAR image formation with azimuth interpolation after azimuth transform

    Science.gov (United States)

    Doerry,; Armin W. , Martin; Grant D. , Holzrichter; Michael, W [Albuquerque, NM

    2008-07-08

    Two-dimensional SAR data can be processed into a rectangular grid format by subjecting the SAR data to a Fourier transform operation, and thereafter to a corresponding interpolation operation. Because the interpolation operation follows the Fourier transform operation, the interpolation operation can be simplified, and the effect of interpolation errors can be diminished. This provides for the possibility of both reducing the re-grid processing time, and improving the image quality.

  16. Literature-Related Discovery: Potential Treatments and Preventives for SARS

    Science.gov (United States)

    2010-01-01

    We recently demonstrated that kefir modulates the immune response in mice, increasing the number of IgA+ cells in the intestinal and bronchial...retrieval and analysis of the core SARS literature and literatures related directly to the core SARS literature (e.g., immune system component literatures...According to recent reviews of the pandemic, none of the drugs worked. Those who recovered did so by natural means; their immune systems were

  17. Restoration of polarimetric SAR images using simulated annealing

    DEFF Research Database (Denmark)

    Schou, Jesper; Skriver, Henning

    2001-01-01

    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......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...

  18. Detection of sinkhole precursors through SAR interferometry: radar and geological considerations

    CSIR Research Space (South Africa)

    Theron, Andre

    2017-06-01

    Full Text Available TerraSAR-X were acquired over a full year. DInSAR results revealed the presence of three previously unknown deformation features, one of which could be confirmed by subsequent field investigations. Furthermore, a water supply pipeline ruptured six months...

  19. Methods of evaluating the effects of coding on SAR data

    Science.gov (United States)

    Dutkiewicz, Melanie; Cumming, Ian

    1993-01-01

    It is recognized that mean square error (MSE) is not a sufficient criterion for determining the acceptability of an image reconstructed from data that has been compressed and decompressed using an encoding algorithm. In the case of Synthetic Aperture Radar (SAR) data, it is also deemed to be insufficient to display the reconstructed image (and perhaps error image) alongside the original and make a (subjective) judgment as to the quality of the reconstructed data. In this paper we suggest a number of additional evaluation criteria which we feel should be included as evaluation metrics in SAR data encoding experiments. These criteria have been specifically chosen to provide a means of ensuring that the important information in the SAR data is preserved. The paper also presents the results of an investigation into the effects of coding on SAR data fidelity when the coding is applied in (1) the signal data domain, and (2) the image domain. An analysis of the results highlights the shortcomings of the MSE criterion, and shows which of the suggested additional criterion have been found to be most important.

  20. 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.

  1. The InSAR Scientific Computing Environment (ISCE): A Python Framework for Earth Science

    Science.gov (United States)

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

    2015-12-01

    The InSAR Scientific Computing Environment (ISCE, funded by NASA ESTO) provides a modern computing framework for geodetic image processing of InSAR data from a diverse array of radar satellites and aircraft. ISCE is both a modular, flexible, and extensible framework for building software components and applications as well as a toolbox of applications for processing raw or focused InSAR and Polarimetric InSAR data. The ISCE framework contains object-oriented Python components layered to construct Python InSAR components that manage legacy Fortran/C InSAR programs. Components are independently configurable in a layered manner to provide maximum control. Polymorphism is used to define a workflow in terms of abstract facilities for each processing step that are realized by specific components at run-time. This enables a single workflow to work on either raw or focused data from all sensors. ISCE can serve as the core of a production center to process Level-0 radar data to Level-3 products, but is amenable to interactive processing approaches that allow scientists to experiment with data to explore new ways of doing science with InSAR data. The NASA-ISRO SAR (NISAR) Mission will deliver data of unprecedented quantity and quality, making possible global-scale studies in climate research, natural hazards, and Earth's ecosystems. 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 new data. NISAR will be but one mission in a constellation of radar satellites in the future delivering such data. ISCE currently supports all publicly available strip map mode space-borne SAR data since ERS and is expected to include support for upcoming missions. ISCE has been incorporated into two prototype cloud-based systems that have demonstrated its elasticity in addressing larger data processing problems in a "production" context and its ability to be

  2. SU-F-I-27: Measurement of SAR and Temperature Elevation During MRI Scans

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Y [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2016-06-15

    Purpose: The poor reliability and repeatability of the manufacturer-reported SAR values on clinical MRI systems have been acknowledged. The purpose of this study is to not only measure SAR values, but also RF-induced temperature elevation at 1.5 and 3T MRI systems. Methods: SAR measurement experiment was performed at 1.5 and 3T. Three MRI RF sequences (T1w TSE, T1w inversion recovery, and T2w TSE) with imaging parameters were selected. A hydroxyl-ethylcelluose (HEC) gelled saline phantom mimicking human body tissue was made. Human torso phantom were constructed, based on Korean adult standard anthropometric reference data (Fig.1). FDTD method was utilized to calculate the SAR distribution using Sim4Life software. Based on the results of the simulation, 4 electrical field (E-field) sensors were located inside the phantom. 55 Fiber Bragg Grating (FBG) temperature sensors (27 sensors in upper and lower cover lids, and one sensor located in the center as a reference) were located inside the phantom to measure temperature change during MRI scan (Fig.2). Results: Simulation shows that SAR value is 0.4 W/kg in the periphery and 0.001 W/kg in the center (Fig.2). One 1.5T and one of two 3T MRI systems represent that the measured SAR values were lower than MRI scanner-reported SAR values. However, the other 3T MRI scanner shows that the averaged SAR values measured by probe 2, 3, and 4 are 6.83, 7.59, and 6.01 W/kg, compared to MRI scanner-reported whole body SAR value (<1.5 W/kg) for T2w TSE (Table 1). The temperature elevation measured by FBG sensors is 5.2°C in the lateral shoulder, 5.1°C in the underarm, 4.7°C in the anterior axilla, 4.8°C in the posterior axilla, and 4.8°C in the lateral waist for T2w TSE (Fig.3). Conclusion: It is essential to assess the safety of MRI system for patient by measuring accurate SAR deposited in the body during clinical MRI.

  3. High Resolution SAR Imaging Employing Geometric Features for Extracting Seismic Damage of Buildings

    Science.gov (United States)

    Cui, L. P.; Wang, X. P.; Dou, A. X.; Ding, X.

    2018-04-01

    Synthetic Aperture Radar (SAR) image is relatively easy to acquire but difficult for interpretation. This paper probes how to identify seismic damage of building using geometric features of SAR. The SAR imaging geometric features of buildings, such as the high intensity layover, bright line induced by double bounce backscattering and dark shadow is analysed, and show obvious differences texture features of homogeneity, similarity and entropy in combinatorial imaging geometric regions between the un-collapsed and collapsed buildings in airborne SAR images acquired in Yushu city damaged by 2010 Ms7.1 Yushu, Qinghai, China earthquake, which implicates a potential capability to discriminate collapsed and un-collapsed buildings from SAR image. Study also shows that the proportion of highlight (layover & bright line) area (HA) is related to the seismic damage degree, thus a SAR image damage index (SARDI), which related to the ratio of HA to the building occupation are of building in a street block (SA), is proposed. While HA is identified through feature extraction with high-pass and low-pass filtering of SAR image in frequency domain. A partial region with 58 natural street blocks in the Yushu City are selected as study area. Then according to the above method, HA is extracted, SARDI is then calculated and further classified into 3 classes. The results show effective through validation check with seismic damage classes interpreted artificially from post-earthquake airborne high resolution optical image, which shows total classification accuracy 89.3 %, Kappa coefficient 0.79 and identical to the practical seismic damage distribution. The results are also compared and discussed with the building damage identified from SAR image available by other authors.

  4. Feature-Based Nonlocal Polarimetric SAR Filtering

    Directory of Open Access Journals (Sweden)

    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.

  5. Rapid Flood Map Generation from Spaceborne SAR Observations

    Science.gov (United States)

    Yun, S. H.; Liang, C.; Manipon, G.; Jung, J.; Gurrola, E. M.; Owen, S. E.; Hua, H.; Agram, P. S.; Webb, F.; Sacco, G. F.; Rosen, P. A.; Simons, M.

    2016-12-01

    The Advanced Rapid Imaging and Analysis (ARIA) team has responded to the January 2016 US Midwest Floods along the Mississippi River. Daily teleconferences with FEMA, NOAA, NGA, and USGS, provided information on precipitation and flood crest migration, based on which we coordinated with the Japanese Aerospace Exploration Agency (JAXA) through NASA headquarters for JAXA's ALOS-2 timely tasking over two paths. We produced flood extent maps using ALOS-2 SM3 mode Level 1.5 data that were provided through the International Charter and stored at the US Geological Survey's Hazards Data Distribution System (HDDS) archive. On January 6, the first four frames (70 km x 240 km) were acquired, which included the City of Memphis. We registered post-event SAR images to pre-event images, applied radiometric calibration, took a logarithm of the ratio of the two images. Two thresholds were applied to represent flooded areas that became open water (colored in blue) and flooded areas with tall vegetation (colored in red). The second path was acquired on January 11 further down along the Mississippi River. Seven frames (70 km x 420 km) were acquired and flood maps were created in the similar fashion. The maps were delivered to the FEMA as well as posted on ARIA's public website. The FEMA stated that SAR provides inspection priority for optical imagery and ground response. The ALOS-2 data and the products have been a very important source of information during this response as the flood crest has moved down stream. The SAR data continue to be an important resource during times when optical observations are often not useful. In close collaboration with FEMA and USGS, we also work on other flood events including June 2016 China Floods using European Space Agency's (ESA's) Sentienl-1 data, to produce flood extent maps and identify algorithmic needs and ARIA system's requirements to automate and rapidly produce and deliver flood maps for future events. With the addition of Sentinel-1B

  6. Structural Modeling and Analysis on Dynamic Characteristics of Antenna Pedestal in Airborne SAR

    Directory of Open Access Journals (Sweden)

    He Li-ping

    2012-06-01

    Full Text Available Finite element modeling and structural dynamic characteristics of antenna pedestal in airborne SAR were studied in this paper. The Finite element model of antenna pedestal in airborne SAR was set up on the basis of structural dynamic theory, then, the key technologies of dynamic simulation were pointed out, and the modal analysis and transient analysis were carried out. Simulation results show that the dynamic characteristics of antenna pedestal in airborne SAR can meet the requirements of servo bandwidth and structural strength. The fast finite element modeling and simulation method proposed in this paper are of great significance to the weight reducing design of antenna pedestal in airborne SAR.

  7. Urban Aerodynamic Roughness Length Mapping Using Multitemporal SAR Data

    Directory of Open Access Journals (Sweden)

    Fengli Zhang

    2017-01-01

    Full Text Available Aerodynamic roughness is very important to urban meteorological and climate studies. Radar remote sensing is considered to be an effective means for aerodynamic roughness retrieval because radar backscattering is sensitive to the surface roughness and geometric structure of a given target. In this paper, a methodology for aerodynamic roughness length estimation using SAR data in urban areas is introduced. The scale and orientation characteristics of backscattering of various targets in urban areas were firstly extracted and analyzed, which showed great potential of SAR data for urban roughness elements characterization. Then the ground truth aerodynamic roughness was calculated from wind gradient data acquired by the meteorological tower using fitting and iterative method. And then the optimal dimension of the upwind sector for the aerodynamic roughness calculation was determined through a correlation analysis between backscattering extracted from SAR data at various upwind sector areas and the aerodynamic roughness calculated from the meteorological tower data. Finally a quantitative relationship was set up to retrieve the aerodynamic roughness length from SAR data. Experiments based on ALOS PALSAR and COSMO-SkyMed data from 2006 to 2011 prove that the proposed methodology can provide accurate roughness length estimations for the spatial and temporal analysis of urban surface.

  8. Classification of sea-ice types in SAR imagery

    International Nuclear Information System (INIS)

    Baraldi, A.; Parmiggiani, F.

    2001-01-01

    It is presented a supervised three-stage classification (labeling) scheme applied to SAR images of polar regions for detecting different sea-ice types. The three-stage labeling procedure consists of: 1) a speckle noise filtering stage, based on a sequence of contour detection, segmentation and filtering steps, which removes SAR speckle noise (and texture information as well) without losing spatial details; 2) a second stage providing Bayesian, maximum-α-posteriori, hierarchical (coarse-to-fine), adaptive (data-driven) and contextual labeling of piecewise constant intensity images featuring little useful texture information; and 3) an output stage providing a many-to-one relationship between second stage output categories (types or clusters) and desired output classes. Modules 1) and 2), which demonstrated their validity in several applications in the existing literature, are briefly recalled in the current paper. The proposed labeling scheme features some interesting functional properties when applied to sea-ice SAR images: it is easy to use, i.e., it requires minor user interaction, is robust to changes in input conditions and performs better than a non-contextual (per-pixel) classifier. Application results are presented and discussed for a pair of SAR images extracted, respectively, from an ERS-1 scene acquired on November 1992 over the Bellingshausen Sea (Antarctica) and from an ERS-2 scene of the East Greenland Sea acquired on March 1997 when a field experiment by the research vessel Jan Ma yen was conducted in the same area

  9. 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.

  10. How change of public transportation usage reveals fear of the SARS virus in a city.

    Science.gov (United States)

    Wang, Kuo-Ying

    2014-01-01

    The outbreaks of the severe acute respiratory syndrome (SARS) epidemic in 2003 resulted in unprecedented impacts on people's daily life. One of the most significant impacts to people is the fear of contacting the SARS virus while engaging daily routine activity. Here we use data from daily underground ridership in Taipei City and daily reported new SARS cases in Taiwan to model the dynamics of the public fear of the SARS virus during the wax and wane of the SARS period. We found that for each reported new SARS case there is an immediate loss of about 1200 underground ridership (the fresh fear). These daily loss rates dissipate to the following days with an e-folding time of about 28 days, reflecting the public perception on the risk of contacting SARS virus when traveling with the underground system (the residual fear). About 50% of daily ridership was lost during the peak of the 2003 SARS period, compared with the loss of 80% daily ridership during the closure of the underground system after Typhoon Nari, the loss of 50-70% ridership due to the closure of the governmental offices and schools during typhoon periods, and the loss of 60% daily ridership during Chinese New Year holidays.

  11. How change of public transportation usage reveals fear of the SARS virus in a city.

    Directory of Open Access Journals (Sweden)

    Kuo-Ying Wang

    Full Text Available The outbreaks of the severe acute respiratory syndrome (SARS epidemic in 2003 resulted in unprecedented impacts on people's daily life. One of the most significant impacts to people is the fear of contacting the SARS virus while engaging daily routine activity. Here we use data from daily underground ridership in Taipei City and daily reported new SARS cases in Taiwan to model the dynamics of the public fear of the SARS virus during the wax and wane of the SARS period. We found that for each reported new SARS case there is an immediate loss of about 1200 underground ridership (the fresh fear. These daily loss rates dissipate to the following days with an e-folding time of about 28 days, reflecting the public perception on the risk of contacting SARS virus when traveling with the underground system (the residual fear. About 50% of daily ridership was lost during the peak of the 2003 SARS period, compared with the loss of 80% daily ridership during the closure of the underground system after Typhoon Nari, the loss of 50-70% ridership due to the closure of the governmental offices and schools during typhoon periods, and the loss of 60% daily ridership during Chinese New Year holidays.

  12. 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.

  13. Perceived Threat, Risk Perception, and Efficacy Beliefs Related to SARS and Other (Emerging) Infectious Diseases

    DEFF Research Database (Denmark)

    de Zwart, Onno; Veldhuijzen, Irene; Elam, Gillian

    2009-01-01

    PURPOSE: To study the levels of perceived threat, perceived severity, perceived vulnerability, response efficacy, and self-efficacy for severe acute respiratory syndrome (SARS) and eight other diseases in five European and three Asian countries. METHOD: A computer-assisted phone survey was conduc......PURPOSE: To study the levels of perceived threat, perceived severity, perceived vulnerability, response efficacy, and self-efficacy for severe acute respiratory syndrome (SARS) and eight other diseases in five European and three Asian countries. METHOD: A computer-assisted phone survey...... was conducted among 3,436 respondents. The questionnaire focused on perceived threat, vulnerability, severity, response efficacy, and self-efficacy related to SARS and eight other diseases. RESULTS: Perceived threat of SARS in case of an outbreak in the country was higher than that of other diseases. Perceived...... vulnerability of SARS was at an intermediate level and perceived severity was high compared to other diseases. Perceived threat for SARS varied between countries in Europe and Asia with a higher perceived severity of SARS in Europe and a higher perceived vulnerability in Asia. Response efficacy and self...

  14. 7 T body MRI: B1 shimming with simultaneous SAR reduction

    International Nuclear Information System (INIS)

    Bergen, Bob van den; Berg, Cornelis A T van den; Bartels, Lambertus W; Lagendijk, Jan J W

    2007-01-01

    The high frequency of the radiofrequency (RF) fields used in high field magnetic resonance imaging (MRI) results in electromagnetic field variations that can cause local regions to have a large specific absorption rate (SAR) and/or a low excitation. In this study, we evaluated the use of a B 1 shimming technique which can simultaneously improve the B + 1 homogeneity and reduce the SAR for whole body imaging at 7 T. Optimizations for four individual anatomies showed a reduction up to 74% of the peak SAR values with respect to a quadrature excitation and a simultaneous improvement of the B + 1 homogeneity varying between 39 and 75% for different optimization parameters. The average SAR was reduced with approximately 50% for all optimizations. The optimized phase and amplitude settings from an elliptical phantom model were applied to four realistic human anatomy models to evaluate whether a generic application without prior knowledge of the detailed human anatomy is possible. This resulted in an average improvement of the B + 1 homogeneity of 37% and an average reduction of the maximum and average SAR of 50 and 55%, respectively. It can be concluded that this generic method can be used as a simple method to improve the prospects of 7 T body imaging

  15. Improvement of the Accuracy of InSAR Image Co-Registration Based On Tie Points – A Review

    Directory of Open Access Journals (Sweden)

    Xiaoli Ding

    2009-02-01

    Full Text Available Interferometric Synthetic Aperture Radar (InSAR is a new measurement technology, making use of the phase information contained in the Synthetic Aperture Radar (SAR images. InSAR has been recognized as a potential tool for the generation of digital elevation models (DEMs and the measurement of ground surface deformations. However, many critical factors affect the quality of InSAR data and limit its applications. One of the factors is InSAR data processing, which consists of image co-registration, interferogram generation, phase unwrapping and geocoding. The co-registration of InSAR images is the first step and dramatically influences the accuracy of InSAR products. In this paper, the principle and processing procedures of InSAR techniques are reviewed. One of important factors, tie points, to be considered in the improvement of the accuracy of InSAR image co-registration are emphatically reviewed, such as interval of tie points, extraction of feature points, window size for tie point matching and the measurement for the quality of an interferogram.

  16. SAR Imagery Simulation of Ship Based on Electromagnetic Calculations and Sea Clutter Modelling for Classification Applications

    International Nuclear Information System (INIS)

    Ji, K F; Zhao, Z; Xing, X W; Zou, H X; Zhou, S L

    2014-01-01

    Ship detection and classification with space-borne SAR has many potential applications within the maritime surveillance, fishery activity management, monitoring ship traffic, and military security. While ship detection techniques with SAR imagery are well established, ship classification is still an open issue. One of the main reasons may be ascribed to the difficulties on acquiring the required quantities of real data of vessels under different observation and environmental conditions with precise ground truth. Therefore, simulation of SAR images with high scenario flexibility and reasonable computation costs is compulsory for ship classification algorithms development. However, the simulation of SAR imagery of ship over sea surface is challenging. Though great efforts have been devoted to tackle this difficult problem, it is far from being conquered. This paper proposes a novel scheme for SAR imagery simulation of ship over sea surface. The simulation is implemented based on high frequency electromagnetic calculations methods of PO, MEC, PTD and GO. SAR imagery of sea clutter is modelled by the representative K-distribution clutter model. Then, the simulated SAR imagery of ship can be produced by inserting the simulated SAR imagery chips of ship into the SAR imagery of sea clutter. The proposed scheme has been validated with canonical and complex ship targets over a typical sea scene

  17. Crisis prevention and management during SARS outbreak, Singapore.

    Science.gov (United States)

    Quah, Stella R; Hin-Peng, Lee

    2004-02-01

    We discuss crisis prevention and management during the first 3 months of the severe acute respiratory syndrome (SARS) outbreak in Singapore. Four public health issues were considered: prevention measures, self-health evaluation, SARS knowledge, and appraisal of crisis management. We conducted telephone interviews with a representative sample of 1,201 adults, > or = 21 years of age. We found that sex, age, and attitude (anxiety and perception of open communication with authorities) were associated with practicing preventive measures. Analysis of Singapore's outbreak improves our understanding of the social dimensions of infectious disease outbreaks.

  18. Delta-proteobacterial SAR324 group in hydrothermal plumes on the South Mid-Atlantic Ridge

    KAUST Repository

    Cao, Huiluo

    2016-03-08

    In the dark ocean, the SAR324 group of Delta-proteobacteria has been associated with a chemolithotrophic lifestyle. However, their electron transport chain for energy generation and information system has not yet been well characterized. In the present study, four SAR324 draft genomes were extracted from metagenomes sampled from hydrothermal plumes in the South Mid-Atlantic Ridge. We describe novel electron transport chain components in the SAR324 group, particularly the alternative complex III, which is involved in energy generation. Moreover, we propose that the C-type cytochrome, for example the C553, may play a novel role in electron transfer, adding to our knowledge regarding the energy generation process in the SAR324 cluster. The central carbon metabolism in the described SAR324 genomes exhibits several new features other than methanotrophy e.g. aromatic compound degradation. This suggests that methane oxidation may not be the main central carbon metabolism component in SAR324 cluster bacteria. The reductive acetyl-CoA pathway may potentially be essential in carbon fixation due to the absence of components from the Calvin-Benson cycle. Our study provides insight into the role of recombination events in shaping the genome of the SAR324 group based on a larger number of repeat regions observed, which has been overlooked thus far.

  19. Operational SAR-based sea ice drift monitoring over the Baltic Sea

    Directory of Open Access Journals (Sweden)

    J. Karvonen

    2012-07-01

    Full Text Available An algorithm for computing ice drift from pairs of synthetic aperture radar (SAR images covering a common area has been developed at FMI. The algorithm has been developed based on the C-band SAR data over the Baltic Sea. It is based on phase correlation in two scales (coarse and fine with some additional constraints. The algorithm has been running operationally in the Baltic Sea from the beginning of 2011, using Radarsat-1 ScanSAR wide mode and Envisat ASAR wide swath mode data. The resulting ice drift fields are publicly available as part of the MyOcean EC project. The SAR-based ice drift vectors have been compared to the drift vectors from drifter buoys in the Baltic Sea during the first operational season, and also these validation results are shown in this paper. Also some navigationally useful sea ice quantities, which can be derived from ice drift vector fields, are presented.

  20. Integrated Data Processing Methodology for Airborne Repeat-pass Differential SAR Interferometry

    Science.gov (United States)

    Dou, C.; Guo, H.; Han, C.; Yue, X.; Zhao, Y.

    2014-11-01

    Short temporal baseline and multiple ground deformation information can be derived from the airborne differential synthetic aperture radar Interforemetry (D-InSAR). However, affected by the turbulence of the air, the aircraft would deviate from the designed flight path with high frequent vibrations and changes both in the flight trajectory and attitude. Restricted by the accuracy of the position and orientation system (POS), these high frequent deviations can not be accurately reported, which would pose great challenges in motion compensation and interferometric process. Thus, these challenges constrain its wider applications. The objective of this paper is to investigate the accurate estimation and compensation of the residual motion errors in the airborne SAR imagery and time-varying baseline errors between the diffirent data acquirations, furthermore, to explore the integration data processing theory for the airborne D-InSAR system, and thus help to accomplish the correct derivation of the ground deformation by using the airborne D-InSAR measurements.

  1. Analysis on Vertical Scattering Signatures in Forestry with PolInSAR

    Science.gov (United States)

    Guo, Shenglong; Li, Yang; Zhang, Jingjing; Hong, Wen

    2014-11-01

    We apply accurate topographic phase to the Freeman-Durden decomposition for polarimetric SAR interferometry (PolInSAR) data. The cross correlation matrix obtained from PolInSAR observations can be decomposed into three scattering mechanisms matrices accounting for the odd-bounce, double-bounce and volume scattering. We estimate the phase based on the Random volume over Ground (RVoG) model, and as the initial input parameter of the numerical method which is used to solve the parameters of decomposition. In addition, the modified volume scattering model introduced by Y. Yamaguchi is applied to the PolInSAR target decomposition in forest areas rather than the pure random volume scattering as proposed by Freeman-Durden to make best fit to the actual measured data. This method can accurately retrieve the magnitude associated with each mechanism and their vertical location along the vertical dimension. We test the algorithms with L- and P- band simulated data.

  2. Mars Mission Concepts: SAR and Solar Electric Propulsion

    Science.gov (United States)

    Elsperman, M.; Klaus, K.; Smith, D. B.; Clifford, S. M.; Lawrence, S. J.

    2012-12-01

    Introduction: The time has come to leverage technology advances (including advances in autonomous operation and propulsion technology) to reduce the cost and increase the flight rate of planetary missions, while actively developing a scientific and engineering workforce to achieve national space objectives. Mission Science at Mars: A SAR imaging radar offers an ability to conduct high resolution investigations of the shallow (Models uniquely useful for exploration planning and science purposes. Since the SAR and the notional high-resolution stereo imaging system would be huge data volume producers - to maximize the science return we are currently considering the usage of laser communications systems; this notional spacecraft represents one pathway to evaluate the utility of laser communications in planetary exploration while providing useful science return.. Mission Concept: Using a common space craft for multiple missions reduces costs. Solar electric propulsion (SEP) provides the flexibility required for multiple mission objectives. SEP provides the greatest payload advantage albeit at the sacrifice of mission time. Our concept involves using a SEP enabled space craft (Boeing 702SP) with a highly capable SAR imager that also conducts autonomous rendezvous and docking experiments accomplished from Mars orbit. Our concept of operations is to launch on May 5, 2018 using a launch vehicle with 2000kg launch capacity with a C3 of 7.4. After reaching Mars it takes 145 days to spiral down to a 250 km orbit above the surface of Mars when Mars SAR operations begin. Summary/Conclusions: A robust and compelling Mars mission can be designed to meet the 2018 Mars launch window opportunity. Using advanced in-space power and propulsion technologies like High Power Solar Electric Propulsion provides enormous mission flexibility to execute the baseline science mission and conduct necessary Mars Sample Return Technology Demonstrations in Mars orbit on the same mission. An

  3. SARS Patients and Their Close Contacts

    Science.gov (United States)

    ... Outreach Workers VIII. Infection Control for Laboratory and Pathology Procedures IX. Occupational Health Issues Appendix I1 Appendix ... SARS was recognized as a global threat in March 2003, after first appearing in Southern China in ...

  4. p53 down-regulates SARS coronavirus replication and is targeted by the SARS-unique domain and PLpro via E3 ubiquitin ligase RCHY1

    Science.gov (United States)

    Ma-Lauer, Yue; Carbajo-Lozoya, Javier; Müller, Marcel A.; Deng, Wen; Lei, Jian; Meyer, Benjamin; Kusov, Yuri; von Brunn, Brigitte; Bairad, Dev Raj; Hünten, Sabine; Drosten, Christian; Hermeking, Heiko; Leonhardt, Heinrich; Mann, Matthias; Hilgenfeld, Rolf; von Brunn, Albrecht

    2016-01-01

    Highly pathogenic severe acute respiratory syndrome coronavirus (SARS-CoV) has developed strategies to inhibit host immune recognition. We identify cellular E3 ubiquitin ligase ring-finger and CHY zinc-finger domain-containing 1 (RCHY1) as an interacting partner of the viral SARS-unique domain (SUD) and papain-like protease (PLpro), and, as a consequence, the involvement of cellular p53 as antagonist of coronaviral replication. Residues 95–144 of RCHY1 and 389–652 of SUD (SUD-NM) subdomains are crucial for interaction. Association with SUD increases the stability of RCHY1 and augments RCHY1-mediated ubiquitination as well as degradation of p53. The calcium/calmodulin-dependent protein kinase II delta (CAMK2D), which normally influences RCHY1 stability by phosphorylation, also binds to SUD. In vivo phosphorylation shows that SUD does not regulate phosphorylation of RCHY1 via CAMK2D. Similarly to SUD, the PLpros from SARS-CoV, MERS-CoV, and HCoV-NL63 physically interact with and stabilize RCHY1, and thus trigger degradation of endogenous p53. The SARS-CoV papain-like protease is encoded next to SUD within nonstructural protein 3. A SUD–PLpro fusion interacts with RCHY1 more intensively and causes stronger p53 degradation than SARS-CoV PLpro alone. We show that p53 inhibits replication of infectious SARS-CoV as well as of replicons and human coronavirus NL63. Hence, human coronaviruses antagonize the viral inhibitor p53 via stabilizing RCHY1 and promoting RCHY1-mediated p53 degradation. SUD functions as an enhancer to strengthen interaction between RCHY1 and nonstructural protein 3, leading to a further increase in in p53 degradation. The significance of these findings is that down-regulation of p53 as a major player in antiviral innate immunity provides a long-sought explanation for delayed activities of respective genes. PMID:27519799

  5. Ionospheric effects on DInSAR measurements of interseismic deformation in China

    Science.gov (United States)

    Gong, W.; Shan, X.; Song, X.; Liao, H.; Meyer, F. J.

    2017-12-01

    Interseismic deformation signals are small ground displacement that is critical to monitor the strain accumulates of major faults to foresee the potential seismic hazard. Accurate measurements of surface deformation could help recognize and interpret even subtle displacement and to give a better understanding of active fault behavior. However, the value and applicability of InSAR for inter-seismic monitoring problems is limited by the influence of temporal decorrelation and electromagnetic path delay variations (atmospheric disturbance), both reducing the sensitivity and accuracy of the technique. Ionospheric signal, a major part of atmospheric disturbance in InSAR, is related to the density of free electrons along the ray path, thus, that is dependent on the SAR signal frequency. Ionosphere induced phase distortions can lead to azimuth/range defocusing, geometry distortions and interferometric phase distortions. Some ionosphere phenomenon have been reported more severe at equatorial region and polar zones, e.g., ionosphere irregularity, while for middle latitude regions like West China it has not been thoroughly analyzed. Thus, this study is focus on the evaluation of ionosphere impacts in middle latitude zone, and its impacts in monitoring interseismic deformation in West China. The outcome would be useful to provide an empiric prior error condition of ionosphere disturbance, which can further benefit InSAR result interpretation and geophysical inversion, as well as the SAR data arrangement in future operational-(cloud) InSAR processing system. The study focus on two parts: 1. We will analyze the temporal-spatial variation of ionosphere and its magnitude at middle latitude zone, and investigate its impacts to current satellite SAR (C-band (Sentinel-1) and L-band (ALOS2) dataset) in earthquake-related deformation studies, especially inter-seismic study. 2. Ionosphere phase patterns at mid latitudes is typically small and the structure is compatibly smooth. This

  6. Population-based Post-crisis Psychological Distress: An Example From the SARS Outbreak in Taiwan

    Science.gov (United States)

    Peng, Eugene Yu-Chang; Lee, Ming-Been; Tsai, Shang-Ta; Yang, Chih-Chien; Morisky, Donald Edward; Tsai, Liang-Ting; Weng, Ya-Ling; Lyu, Shu-Yu

    2011-01-01

    Background/Purpose As a result of the severe acute respiratory syndrome (SARS) pandemic, the World Health Organization placed Taiwan on the travel alert list from May 21 to July 5, 2003. The aim of this study was to explore the post-crisis psychological distress among residents in Taiwan after the SARS epidemic. Methods The target population consisted of a nationwide representative sample of residents aged ≥ 18 years. Data were collected using computer assisted telephone interview systems by stratified random sampling according to geographic area. The survey (n = 1278) was conducted in November 2003, about 4 months after resolution of the SARS crisis in Taiwan. The maximum deviation of sampling error at the 95% confidence level was ± 2.74%. Psychological distress was measured by a question related to subject’s changes in perception of life, plus the five-item Brief Symptom Rating Scale. Multivariate logistic regression was used to examine the correlation of psychological distress. Results About 9.2% of the participants reported that their perceptions of life became more pessimistic following the SARS crisis. The prevalence of psychiatric morbidity was 11.7%. Major predictors of higher levels of pessimism after the SARS epidemic included demographic factors, perception of SARS and pre-paredness, knowing people or having personal experiences of SARS-related discrimination, and individual worries and psychiatric morbidity. The correlates of symptomatic cases, as indicated by the five-item Brief Symptom Rating Scale, included age ≥ 50 years, senior high school graduate, and worries about recurrence of SARS. Conclusion Psychological distress was significantly correlated with demographic factors and perception regarding the SARS epidemic. It is suggested that marketing of mental health education should be segmented according to age and education level, which should enhance crisis communication for newly emerging infectious diseases among community populations

  7. Geodetic integration of Sentinel-1A IW data using PSInSAR in Hungary

    Science.gov (United States)

    Farkas, Péter; Hevér, Renáta; Grenerczy, Gyula

    2015-04-01

    ESA's latest Synthetic Aperture Radar (SAR) mission Sentinel-1 is a huge step forward in SAR interferometry. With its default acquisition mode called the Interferometric Wide Swath Mode (IW) areas through all scales can be mapped with an excellent return time of 12 days (while only the Sentinel-1A is in orbit). Its operational data policy is also a novelty, it allows scientific users free and unlimited access to data. It implements a new type of ScanSAR mode called Terrain Observation with Progressive Scan (TOPS) SAR. It has the same resolution as ScanSAR but with better signal-to-noise ratio distribution. The bigger coverage is achieved by rotation of the antenna in the azimuth direction, therefore it requires very precise co-registration because even errors under a pixel accuracy can introduce azimuth phase variations caused by differences in Doppler-centroids. In our work we will summarize the benefits and the drawbacks of the IW mode. We would like to implement the processing chain of GAMMA Remote Sensing of such data for mapping surface motion with special attention to the co-registration step. Not only traditional InSAR but the advanced method of Persistent Scatterer InSAR (PSInSAR) will be performed and presented as well. PS coverage, along with coherence, is expected to be good due to the small perpendicular and temporal baselines. We would also like to integrate these measurements into national geodetic networks using common reference points. We have installed trihedral corner reflectors at some selected sites to aid precise collocation. Thus, we aim to demonstrate that Sentinel-1 can be effectively used for surface movement detection and monitoring and it can also provide valuable information for the improvement of our networks.

  8. Robust adaptive multichannel SAR processing based on covariance matrix reconstruction

    Science.gov (United States)

    Tan, Zhen-ya; He, Feng

    2018-04-01

    With the combination of digital beamforming (DBF) processing, multichannel synthetic aperture radar(SAR) systems in azimuth promise well in high-resolution and wide-swath imaging, whereas conventional processing methods don't take the nonuniformity of scattering coefficient into consideration. This paper brings up a robust adaptive Multichannel SAR processing method which utilizes the Capon spatial spectrum estimator to obtain the spatial spectrum distribution over all ambiguous directions first, and then the interference-plus-noise covariance Matrix is reconstructed based on definition to acquire the Multichannel SAR processing filter. The performance of processing under nonuniform scattering coefficient is promoted by this novel method and it is robust again array errors. The experiments with real measured data demonstrate the effectiveness and robustness of the proposed method.

  9. Understanding the Future Market for NovaSAR-S Flood Mapping Products Using Data Mining and Simulation

    Science.gov (United States)

    Lavender, Samantha; Haria, Kajal; Cooksley, Geraint; Farman, Alex; Beaton, Thomas

    2016-08-01

    The aim was to understand a future market for NovaSAR-S, with a particular focus on flood mapping, through developing a simple Synthetic Aperture Radar (SAR) simulator that can be used in advance of NovaSAR-S data becoming available.The return signal was determined from a combination of a terrain or elevation model, Envisat S-Band Radar Altimeter (RA)-2, Landsat and CORINE land cover information; allowing for a simulation of a SAR image that's influenced by both the geometry and surface type. The test sites correspond to data from the 2014 AirSAR campaign, and validation is performed by using AirSAR together with Envisat Advanced (ASAR) and Advanced Land Observing Satellite "Daichi" (ALOS) Phased Array type L-Band Synthetic Aperture Radar (PALSAR) data.It's envisaged that the resulting simulated data, and the simulator, will not only aid early understanding of NovaSAR-S, but will also aid the development of flood mapping applications.

  10. Detectability Analysis of Road Vehicles in Radarsat-2 Fully Polarimetric SAR Images for Traffic Monitoring

    Directory of Open Access Journals (Sweden)

    Bo Zhang

    2017-02-01

    Full Text Available By acquiring information over a wide area regardless of weather conditions and solar illumination, space-borne Synthetic Aperture Radar (SAR has the potential to be a promising application for traffic monitoring. However, the backscatter character of a vehicle in a SAR image is unstable and varies with image parameters, such as aspect and incidence angle. To investigate vehicle detectability in SAR images for traffic monitoring applications, images of four common types of vehicles in China were acquired using the fully polarimetric (FP SAR of Radarsat-2 in our experiments. Methods for measuring a vehicle’s aspect angle and backscatter intensity are introduced. The experimental FP SAR images are used to analyze the detectability, which is affected by factors such as vehicle size, vehicle shape, and aspect angle. Moreover, a new metric to improve vehicle detectability in FP SAR images is proposed and compared with the well-known intensity metric. The experimental results show that shape is a crucial factor in affecting the backscatter intensity of vehicles, which also oscillates with varying aspect angle. If the size of a vehicle is smaller than the SAR image resolution, using the intensity metric would result in low detectability. However, it could be improved in an FP SAR image by using the proposed metric. Compared with the intensity metric, the overall detectability is improved from 72% to 90% in our experiments. Therefore, this study indicates that FP SAR images have the ability to detect stationary vehicles on the road and are meaningful for traffic monitoring.

  11. The Establishment of the SAR images database System Based on Oracle and ArcSDE

    International Nuclear Information System (INIS)

    Zhou, Jijin; Li, Zhen; Chen, Quan; Tian, Bangsen

    2014-01-01

    Synthetic aperture radar is a kind of microwave imaging system, and has the advantages of multi-band, multi-polarization and multi-angle. At present, there is no SAR images database system based on typical features. For solving problems in interpretation and identification, a new SAR images database system of the typical features is urgent in the current development need. In this article, a SAR images database system based on Oracle and ArcSDE was constructed. The main works involving are as follows: (1) SAR image data was calibrated and corrected geometrically and geometrically. Besides, the fully polarimetric image was processed as the coherency matrix[T] to preserve the polarimetric information. (2) After analyzing multiple space borne SAR images, the metadata table was defined as: IMAGEID; Name of features; Latitude and Longitude; Sensor name; Range and Azimuth resolution etc. (3) Through the comparison between GeoRaster and ArcSDE, result showed ArcSDE is a more appropriate technology to store images in a central database. The System stores and manages multisource SAR image data well, reflects scattering, geometry, polarization, band and angle characteristics, and combines with analysis of the managed objects and service objects of the database as well as focuses on constructing SAR image system in the aspects of data browse and data retrieval. According the analysis of characteristics of SAR images such as scattering, polarization, incident angle and wave band information, different weights can be given to these characteristics. Then an interpreted tool is formed to provide an efficient platform for interpretation

  12. Atmospheric Phase Delay in Sentinel SAR Interferometry

    Science.gov (United States)

    Krishnakumar, V.; Monserrat, O.; Crosetto, M.; Crippa, B.

    2018-04-01

    The repeat-pass Synthetic Aperture Radio Detection and Ranging (RADAR) Interferometry (InSAR) has been a widely used geodetic technique for observing the Earth's surface, especially for mapping the Earth's topography and deformations. However, InSAR measurements are prone to atmospheric errors. RADAR waves traverse the Earth's atmosphere twice and experience a delay due to atmospheric refraction. The two major layers of the atmosphere (troposphere and ionosphere) are mainly responsible for this delay in the propagating RADAR wave. Previous studies have shown that water vapour and clouds present in the troposphere and the Total Electron Content (TEC) of the ionosphere are responsible for the additional path delay in the RADAR wave. The tropospheric refractivity is mainly dependent on pressure, temperature and partial pressure of water vapour. The tropospheric refractivity leads to an increase in the observed range. These induced propagation delays affect the quality of phase measurement and introduce errors in the topography and deformation fields. The effect of this delay was studied on a differential interferogram (DInSAR). To calculate the amount of tropospheric delay occurred, the meteorological data collected from the Spanish Agencia Estatal de Meteorología (AEMET) and MODIS were used. The interferograms generated from Sentinel-1 carrying C-band Synthetic Aperture RADAR Single Look Complex (SLC) images acquired on the study area are used. The study area consists of different types of scatterers exhibiting different coherence. The existing Saastamoinen model was used to perform a quantitative evaluation of the phase changes caused by pressure, temperature and humidity of the troposphere during the study. Unless the phase values due to atmospheric disturbances are not corrected, it is difficult to obtain accurate measurements. Thus, the atmospheric error correction is essential for all practical applications of DInSAR to avoid inaccurate height and deformation

  13. ATMOSPHERIC PHASE DELAY IN SENTINEL SAR INTERFEROMETRY

    Directory of Open Access Journals (Sweden)

    V. Krishnakumar

    2018-04-01

    Full Text Available The repeat-pass Synthetic Aperture Radio Detection and Ranging (RADAR Interferometry (InSAR has been a widely used geodetic technique for observing the Earth’s surface, especially for mapping the Earth’s topography and deformations. However, InSAR measurements are prone to atmospheric errors. RADAR waves traverse the Earth’s atmosphere twice and experience a delay due to atmospheric refraction. The two major layers of the atmosphere (troposphere and ionosphere are mainly responsible for this delay in the propagating RADAR wave. Previous studies have shown that water vapour and clouds present in the troposphere and the Total Electron Content (TEC of the ionosphere are responsible for the additional path delay in the RADAR wave. The tropospheric refractivity is mainly dependent on pressure, temperature and partial pressure of water vapour. The tropospheric refractivity leads to an increase in the observed range. These induced propagation delays affect the quality of phase measurement and introduce errors in the topography and deformation fields. The effect of this delay was studied on a differential interferogram (DInSAR. To calculate the amount of tropospheric delay occurred, the meteorological data collected from the Spanish Agencia Estatal de Meteorología (AEMET and MODIS were used. The interferograms generated from Sentinel-1 carrying C-band Synthetic Aperture RADAR Single Look Complex (SLC images acquired on the study area are used. The study area consists of different types of scatterers exhibiting different coherence. The existing Saastamoinen model was used to perform a quantitative evaluation of the phase changes caused by pressure, temperature and humidity of the troposphere during the study. Unless the phase values due to atmospheric disturbances are not corrected, it is difficult to obtain accurate measurements. Thus, the atmospheric error correction is essential for all practical applications of DInSAR to avoid inaccurate

  14. Basic to Advanced InSAR Processing: GMTSAR

    Science.gov (United States)

    Sandwell, D. T.; Xu, X.; Baker, S.; Hogrelius, A.; Mellors, R. J.; Tong, X.; Wei, M.; Wessel, P.

    2017-12-01

    Monitoring crustal deformation using InSAR is becoming a standard technique for the science and application communities. Optimal use of the new data streams from Sentinel-1 and NISAR will require open software tools as well as education on the strengths and limitations of the InSAR methods. Over the past decade we have developed freely available, open-source software for processing InSAR data. The software relies on the Generic Mapping Tools (GMT) for the back-end data analysis and display and is thus called GMTSAR. With startup funding from NSF, we accelerated the development of GMTSAR to include more satellite data sources and provide better integration and distribution with GMT. In addition, with support from UNAVCO we have offered 6 GMTSAR short courses to educate mostly novice InSAR users. Currently, the software is used by hundreds of scientists and engineers around the world to study deformation at more than 4300 different sites. The most challenging aspect of the recent software development was the transition from image alignment using the cross-correlation method to a completely new alignment algorithm that uses only the precise orbital information to geometrically align images to an accuracy of better than 7 cm. This development was needed to process a new data type that is being acquired by the Sentinel-1A/B satellites. This combination of software and open data is transforming radar interferometry from a research tool into a fully operational time series analysis tool. Over the next 5 years we are planning to continue to broaden the user base through: improved software delivery methods; code hardening; better integration with data archives; support for high level products being developed for NISAR; and continued education and outreach.

  15. Effect of Antenna Pointing Errors on SAR Imaging Considering the Change of the Point Target Location

    Science.gov (United States)

    Zhang, Xin; Liu, Shijie; Yu, Haifeng; Tong, Xiaohua; Huang, Guoman

    2018-04-01

    Towards spaceborne spotlight SAR, the antenna is regulated by the SAR system with specific regularity, so the shaking of the internal mechanism is inevitable. Moreover, external environment also has an effect on the stability of SAR platform. Both of them will cause the jitter of the SAR platform attitude. The platform attitude instability will introduce antenna pointing error on both the azimuth and range directions, and influence the acquisition of SAR original data and ultimate imaging quality. In this paper, the relations between the antenna pointing errors and the three-axis attitude errors are deduced, then the relations between spaceborne spotlight SAR imaging of the point target and antenna pointing errors are analysed based on the paired echo theory, meanwhile, the change of the azimuth antenna gain is considered as the spotlight SAR platform moves ahead. The simulation experiments manifest the effects on spotlight SAR imaging caused by antenna pointing errors are related to the target location, that is, the pointing errors of the antenna beam will severely influence the area far away from the scene centre of azimuth direction in the illuminated scene.

  16. Low cost realization of space-borne synthectic aperture radar - MicroSAR

    Science.gov (United States)

    Carter, D.; Hall, C.

    Spaceborne Earth Observation data has been used for decades in the areas of meteorology and optical imaging. The systems and satellites have, in the main, been owned and operated by a few government institutions and agencies. More recently industrial organizations in North America have joined the list. Few of these, however, include Synthetic Aperture Radar (SAR)., although the additional utility in terms of all weather, 24 hour measurement capability over the Earth's surface is well recognized. Three major factors explain this:1) Relationships between the SAR measurements of radar backscatter and images to the specific information needs have not been seen as sufficiently well understood or robust2) Availability of suitable sources, at the relevant performance and data quality have been inadequate to provide service assurance that is necessary to sustain commercial businesses3) Costs associated with building, launching and operating spaceborne SAR have not been low enough as to achieve an acceptable return of investment. A significant amount of research and development has been undertaken throughout the World to establish reliable and robust algorithms for information extraction from SAR data. Much of this work has been carried out utilizing airborne systems over localized and carefully controlled regions. In addition, an increasing number of pilot services have been offered by geo-information providers. This has allowed customer confidence to grow. With the status of spaceborne SAR being effectively in the development phase, commercial funding has been scarce, and there has been need to rely on government and institutional budgets. Today the increasing maturity of the technology of SAR and its applications is beginning to attract the commercial sector. This is the funding necessary to realize sufficient assets to be able to provide a robust supply of SAR data to the geo-information providers and subsequently a reliable service to customers. Reducing the costs

  17. Optimizing deep hyperthermia treatments: are locations of patient pain complaints correlated with modelled SAR peak locations?

    Energy Technology Data Exchange (ETDEWEB)

    Canters, R A M; Franckena, M; Van der Zee, J; Van Rhoon, G C, E-mail: r.canters@erasmusmc.nl [Department of Radiation Oncology, Erasmus MC Daniel den Hoed Cancer Centre, Rotterdam, PO Box 5201, 3008 AE Rotterdam (Netherlands)

    2011-01-21

    During deep hyperthermia treatment, patient pain complaints due to heating are common when maximizing power. Hence, there exists a good rationale to investigate whether the locations of predicted SAR peaks by hyperthermia treatment planning (HTP) are correlated with the locations of patient pain during treatment. A retrospective analysis was performed, using the treatment reports of 35 patients treated with deep hyperthermia controlled by extensive treatment planning. For various SAR indicators, the average distance from a SAR peak to a patient discomfort location was calculated, for each complaint. The investigated V{sub 0.1closest} (i.e. the part of the 0.1th SAR percentile closest to the patient complaint) performed the best, and leads to an average distance between the SAR peak and the complaint location of 3.9 cm. Other SAR indicators produced average distances that were all above 10 cm. Further, the predicted SAR peak location with V{sub 0.1} provides a 77% match with the region of complaint. The current study demonstrates that HTP is able to provide a global indication of the regions where hotspots during treatment will most likely occur. Further development of this technology is necessary in order to use HTP as a valuable toll for objective and advanced SAR steering. The latter is especially valid for applications that enable 3D SAR steering.

  18. Optimizing deep hyperthermia treatments: are locations of patient pain complaints correlated with modelled SAR peak locations?

    International Nuclear Information System (INIS)

    Canters, R A M; Franckena, M; Van der Zee, J; Van Rhoon, G C

    2011-01-01

    During deep hyperthermia treatment, patient pain complaints due to heating are common when maximizing power. Hence, there exists a good rationale to investigate whether the locations of predicted SAR peaks by hyperthermia treatment planning (HTP) are correlated with the locations of patient pain during treatment. A retrospective analysis was performed, using the treatment reports of 35 patients treated with deep hyperthermia controlled by extensive treatment planning. For various SAR indicators, the average distance from a SAR peak to a patient discomfort location was calculated, for each complaint. The investigated V 0.1closest (i.e. the part of the 0.1th SAR percentile closest to the patient complaint) performed the best, and leads to an average distance between the SAR peak and the complaint location of 3.9 cm. Other SAR indicators produced average distances that were all above 10 cm. Further, the predicted SAR peak location with V 0.1 provides a 77% match with the region of complaint. The current study demonstrates that HTP is able to provide a global indication of the regions where hotspots during treatment will most likely occur. Further development of this technology is necessary in order to use HTP as a valuable toll for objective and advanced SAR steering. The latter is especially valid for applications that enable 3D SAR steering.

  19. Monitoring informal settlements using SAR polarimetry

    CSIR Research Space (South Africa)

    Kleynhans, W

    2012-10-01

    Full Text Available for settlement mapping and detection has remained largely unexplored in Southern Africa. The objective of this study is to investigate the possible role that SAR polarimetry could play in the monitoring of informal settlements....

  20. Mobile phone types and SAR characteristics of the human brain

    Science.gov (United States)

    Lee, Ae-Kyoung; Hong, Seon-Eui; Kwon, Jong-Hwa; Choi, Hyung-Do; Cardis, Elisabeth

    2017-04-01

    Mobile phones differ in terms of their operating frequency, outer shape, and form and location of the antennae, all of which affect the spatial distributions of their electromagnetic field and the level of electromagnetic absorption in the human head or brain. For this paper, the specific absorption rate (SAR) was calculated for four anatomical head models at different ages using 11 numerical phone models of different shapes and antenna configurations. The 11 models represent phone types accounting for around 86% of the approximately 1400 commercial phone models released into the Korean market since 2002. Seven of the phone models selected have an internal dual-band antenna, and the remaining four possess an external antenna. Each model was intended to generate an average absorption level equivalent to that of the same type of commercial phone model operating at the maximum available output power. The 1 g peak spatial SAR and ipsilateral and contralateral brain-averaged SARs were reported for all 11 phone models. The effects of the phone type, phone position, operating frequency, and age of head models on the brain SAR were comprehensively determined.

  1. ARBRES: Light-Weight CW/FM SAR Sensors for Small UAVs

    Directory of Open Access Journals (Sweden)

    Xavier Fabregas

    2013-03-01

    Full Text Available This paper describes a pair of compact CW/FM airborne SAR systems for small UAV-based operation (wingspan of 3.5 m for low-cost testing of innovative SAR concepts. Two different SAR instruments, using the C and X bands, have been developed in the context of the ARBRES project, each of them achieving a payload weight below 5 Kg and a volume of 13.5 dm3 (sensor and controller. Every system has a dual receiving channel which allows operation in interferometric or polarimetric modes. Planar printed array antennas are used in both sensors for easy system integration and better isolation between transmitter and receiver subsystems. First experimental tests on board a 3.2 m wingspan commercial radio-controlled aircraft are presented. The SAR images of a field close to an urban area have been focused using a back-projection algorithm. Using the dual channel capability, a single pass interferogram and Digital Elevation Model (DEM has been obtained which agrees with the scene topography. A simple Motion Compensation (MoCo module, based on the information from an Inertial+GPS unit, has been included to compensate platform motion errors with respect to the nominal straight trajectory.

  2. Features of clinical and radiographic appearances of SARS in children

    International Nuclear Information System (INIS)

    Zeng Jinjin; Sun Guoqiang; Shen Kunling; Yang Yonghong; Wei Xinmiao; Lei Gang

    2003-01-01

    Objective: To evaluate the features of clinical and radiographic appearances of SARS in children. Methods: The chest films obtained at clinical presentation and during treatment in 18 children with confirmed SARS were retrospectively evaluated. Results: The main X-ray manifestations included: (1) air-space opacity in 13/18; (2) round lesion with clear margin in 3/18; (3) ground-glass lesions in 2/18; (4) unilateral and single focal involvement was more common in children than in adults (5) no reticular shadow, lymphanopathy or pleural effusion was demonstrated; (6) radiographic changes of foci was not as rapid in children as in adults. The lesions migrated in 1 case. The average absorption time of the lesions was 19 days, and most of them had no remnant. Conclusion: Compare with that in adults , the clinical manifestation was not so severe in children with SARS, and most of the infected children had clear contact history. Chest X-ray appearance in affected children mainly showed unilateral involvement of the lungs with chiefly air-space infiltrates. Remnant lesion of lung is rare in children. Differential diagnosis of SARS in children includes mycoplasma pneumonia or adenovirus pneumonia

  3. Helmand river hydrologic studies using ALOS PALSAR InSAR and ENVISAT altimetry

    Science.gov (United States)

    Lu, Zhong; Kim, J.-W.; Lee, H.; Shum, C.K.; Duan, J.; Ibaraki, M.; Akyilmaz, O.; Read, C.-H.

    2009-01-01

    The Helmand River wetland represents the only fresh-water resource in southern Afghanistan and one of the least mapped water basins in the world. The relatively narrow wetland consists of mostly marshes surrounded by dry lands. In this study, we demonstrate the use of the Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) Interferometric SAR (InSAR) to detect the changes of the Helmand River wetland water level. InSAR images are combined with the geocentric water level measurements from the retracked high-rate (18-Hz) Environmental Satellite (Envisat) radar altimetry to construct absolute water level changes over the marshes. It is demonstrated that the integration of the altimeter and InSAR can provide spatio-temporal measurements of water level variation over the Helmand River marshes where in situ measurements are absent. ?? Taylor & Francis Group, LLC.

  4. Fractionation of fulvic acid by iron and aluminum oxides: influence on copper toxicity to Ceriodaphnia dubia

    Science.gov (United States)

    Smith, Kathleen S.; Ranville, James F.; Lesher, Emily K.; Diedrich, Daniel J.; McKnight, Diane M.; Sofield, Ruth M.

    2014-01-01

    This study examines the effect on aquatic copper toxicity of the chemical fractionation of fulvic acid (FA) that results from its association with iron and aluminum oxyhydroxide precipitates. Fractionated and unfractionated FAs obtained from streamwater and suspended sediment were utilized in acute Cu toxicity tests on ,i>Ceriodaphnia dubia. Toxicity test results with equal FA concentrations (6 mg FA/L) show that the fractionated dissolved FA was 3 times less effective at reducing Cu toxicity (EC50 13 ± 0.6 μg Cu/L) than were the unfractionated dissolved FAs (EC50 39 ± 0.4 and 41 ± 1.2 μg Cu/L). The fractionation is a consequence of preferential sorption of molecules having strong metal-binding (more aromatic) moieties to precipitating Fe- and Al-rich oxyhydroxides, causing the remaining dissolved FA to be depleted in these functional groups. As a result, there is more bioavailable dissolved Cu in the water and hence greater potential for Cu toxicity to aquatic organisms. In predicting Cu toxicity, biotic ligand models (BLMs) take into account dissolved organic carbon (DOC) concentration; however, unless DOC characteristics are accounted for, model predictions can underestimate acute Cu toxicity for water containing fractionated dissolved FA. This may have implications for water-quality criteria in systems containing Fe- and Al-rich sediment, and in mined and mineralized areas in particular. Optical measurements, such as specific ultraviolet absorbance at 254 nm (SUVA254), show promise for use as spectral indicators of DOC chemical fractionation and inferred increased Cu toxicity.

  5. Semi-physical Simulation of the Airborne InSAR based on Rigorous Geometric Model and Real Navigation Data

    Science.gov (United States)

    Changyong, Dou; Huadong, Guo; Chunming, Han; yuquan, Liu; Xijuan, Yue; Yinghui, Zhao

    2014-03-01

    Raw signal simulation is a useful tool for the system design, mission planning, processing algorithm testing, and inversion algorithm design of Synthetic Aperture Radar (SAR). Due to the wide and high frequent variation of aircraft's trajectory and attitude, and the low accuracy of the Position and Orientation System (POS)'s recording data, it's difficult to quantitatively study the sensitivity of the key parameters, i.e., the baseline length and inclination, absolute phase and the orientation of the antennas etc., of the airborne Interferometric SAR (InSAR) system, resulting in challenges for its applications. Furthermore, the imprecise estimation of the installation offset between the Global Positioning System (GPS), Inertial Measurement Unit (IMU) and the InSAR antennas compounds the issue. An airborne interferometric SAR (InSAR) simulation based on the rigorous geometric model and real navigation data is proposed in this paper, providing a way for quantitatively studying the key parameters and for evaluating the effect from the parameters on the applications of airborne InSAR, as photogrammetric mapping, high-resolution Digital Elevation Model (DEM) generation, and surface deformation by Differential InSAR technology, etc. The simulation can also provide reference for the optimal design of the InSAR system and the improvement of InSAR data processing technologies such as motion compensation, imaging, image co-registration, and application parameter retrieval, etc.

  6. Semi-physical Simulation of the Airborne InSAR based on Rigorous Geometric Model and Real Navigation Data

    International Nuclear Information System (INIS)

    Changyong, Dou; Huadong, Guo; Chunming, Han; Yuquan, Liu; Xijuan, Yue; Yinghui, Zhao

    2014-01-01

    Raw signal simulation is a useful tool for the system design, mission planning, processing algorithm testing, and inversion algorithm design of Synthetic Aperture Radar (SAR). Due to the wide and high frequent variation of aircraft's trajectory and attitude, and the low accuracy of the Position and Orientation System (POS)'s recording data, it's difficult to quantitatively study the sensitivity of the key parameters, i.e., the baseline length and inclination, absolute phase and the orientation of the antennas etc., of the airborne Interferometric SAR (InSAR) system, resulting in challenges for its applications. Furthermore, the imprecise estimation of the installation offset between the Global Positioning System (GPS), Inertial Measurement Unit (IMU) and the InSAR antennas compounds the issue. An airborne interferometric SAR (InSAR) simulation based on the rigorous geometric model and real navigation data is proposed in this paper, providing a way for quantitatively studying the key parameters and for evaluating the effect from the parameters on the applications of airborne InSAR, as photogrammetric mapping, high-resolution Digital Elevation Model (DEM) generation, and surface deformation by Differential InSAR technology, etc. The simulation can also provide reference for the optimal design of the InSAR system and the improvement of InSAR data processing technologies such as motion compensation, imaging, image co-registration, and application parameter retrieval, etc

  7. Severe acute respiratory syndrome (SARS): chest radiographic features in children

    Energy Technology Data Exchange (ETDEWEB)

    Babyn, Paul S.; Gahunia, Harpal K.; Manson, David [Department of Diagnostic Imaging, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario (Canada); Chu, Winnie C.W.; Metreweli, Constantine [Prince of Wales Hospital, Shatin (China); Department of Diagnostic Radiology and Organ Imaging, Chinese University of Hong Kong (China); Tsou, Ian Y.Y.; Wansaicheong, Gervais K.L.; Chee, Thomas S.G.; Kaw, Gregory J.L. [Department of Diagnostic Radiology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng (Singapore); Allen, Upton; Bitnun, Ari; Read, Stanley [Division of Infectious Diseases, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario (Canada); Cheng, Frankie W.T.; Fok, Tai-Fai; Hon, Ellis K.L.; Li, Albert M.; Ng, Pak-Cheung [Department of Paediatrics, Chinese University of Hong Kong, Prince of Wales Hospital, 30-32 Ngan Shing Street, Shatin, Hong Kong, SAR (China); Chiu, Man-Chun; Leung, Chi-Wai [Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Lai King Hill Road, Lai Chi Kok, Hong Kong, SAR (China); Khong, Pek L. [Department of Diagnostic Radiology, The University of Hong Kong, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong, SAR (China); Stringer, David A.

    2004-01-01

    We abstracted data (n=62) on the radiologic appearance and course of SARS in pediatric patients with suspect (n=25) or probable (n=37) SARS, diagnosed in five hospital sites located in three cities: Toronto, Singapore, and Hong Kong. Available chest radiographs and thoracic CTs were reviewed for the presence of the following radiographic findings: airspace disease, air bronchograms, airways inflammation and peribronchial thickening, interstitial disease, pleural effusion, and hilar adenopathy. A total of 62 patients (suspect=25, probable=37) were evaluated for SARS. Patient ages ranged from 5.5 months to 17 years and 11.5 months (average, 6 years and 10 months) with a female-to-male ratio of 32:30. Forty-one patients (66.1%) were in close contact with other probable, suspect, or quarantined cases; 10 patients (16.1%) had recently traveled to WHO-designated affected areas within 10 days; and 7 patients (11.2%) were transferred from other hospitals that had SARS patients. Three patients, who did not have close/hospital contact or travel history to affected areas, were classified as SARS cases based on their clinical signs and symptoms and on the fact that they were living in an endemic area. The most prominent clinical presentations were fever, with a temperature over 38 C (100%), cough (62.9%), rhinorrhea (22.6%), myalgia (17.7%), chills (14.5%), and headache (11.3%). Other findings included sore throat (9.7%), gastrointestinal symptoms (9.7%), rigor (8.1%), and lethargy (6.5%). In general, fever and cough were the most common clinical presentations amongst younger pediatric SARS cases (age<10 years), whereas, in addition to these symptoms, headache, myalgia, sore throat, chills, and/or rigor were common in older patients (age{>=}10 years). The chest radiographs of 35.5% of patients were normal. The most prominent radiological findings that were observed in the remaining patients were areas of consolidation (45.2%), often peripheral with multifocal lesions in 22

  8. Severe acute respiratory syndrome (SARS): chest radiographic features in children

    International Nuclear Information System (INIS)

    Babyn, Paul S.; Gahunia, Harpal K.; Manson, David; Chu, Winnie C.W.; Metreweli, Constantine; Tsou, Ian Y.Y.; Wansaicheong, Gervais K.L.; Chee, Thomas S.G.; Kaw, Gregory J.L.; Allen, Upton; Bitnun, Ari; Read, Stanley; Cheng, Frankie W.T.; Fok, Tai-Fai; Hon, Ellis K.L.; Li, Albert M.; Ng, Pak-Cheung; Chiu, Man-Chun; Leung, Chi-Wai; Khong, Pek L.; Stringer, David A.

    2004-01-01

    We abstracted data (n=62) on the radiologic appearance and course of SARS in pediatric patients with suspect (n=25) or probable (n=37) SARS, diagnosed in five hospital sites located in three cities: Toronto, Singapore, and Hong Kong. Available chest radiographs and thoracic CTs were reviewed for the presence of the following radiographic findings: airspace disease, air bronchograms, airways inflammation and peribronchial thickening, interstitial disease, pleural effusion, and hilar adenopathy. A total of 62 patients (suspect=25, probable=37) were evaluated for SARS. Patient ages ranged from 5.5 months to 17 years and 11.5 months (average, 6 years and 10 months) with a female-to-male ratio of 32:30. Forty-one patients (66.1%) were in close contact with other probable, suspect, or quarantined cases; 10 patients (16.1%) had recently traveled to WHO-designated affected areas within 10 days; and 7 patients (11.2%) were transferred from other hospitals that had SARS patients. Three patients, who did not have close/hospital contact or travel history to affected areas, were classified as SARS cases based on their clinical signs and symptoms and on the fact that they were living in an endemic area. The most prominent clinical presentations were fever, with a temperature over 38 C (100%), cough (62.9%), rhinorrhea (22.6%), myalgia (17.7%), chills (14.5%), and headache (11.3%). Other findings included sore throat (9.7%), gastrointestinal symptoms (9.7%), rigor (8.1%), and lethargy (6.5%). In general, fever and cough were the most common clinical presentations amongst younger pediatric SARS cases (age<10 years), whereas, in addition to these symptoms, headache, myalgia, sore throat, chills, and/or rigor were common in older patients (age≥10 years). The chest radiographs of 35.5% of patients were normal. The most prominent radiological findings that were observed in the remaining patients were areas of consolidation (45.2%), often peripheral with multifocal lesions in 22

  9. Tomographic SAR analysis of subsurface ice structure in Greenland: first results

    DEFF Research Database (Denmark)

    Banda, Francesco; Dall, Jørgen; Tebaldini, Stefano

    2013-01-01

    structure with P-band SAR tomography. First results from ESA IceSAR 2012 campaign carried out in south-west Greenland are presented. It is found that significant penetration in the upper layers of glacial subsurface can be achieved up to an extent of about 20–60 m, conditional on the different type...

  10. 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...

  11. Forest Structure Characterization Using Jpl's UAVSAR Multi-Baseline Polarimetric SAR Interferometry and Tomography

    Science.gov (United States)

    Neumann, Maxim; Hensley, Scott; Lavalle, Marco; Ahmed, Razi

    2013-01-01

    This paper concerns forest remote sensing using JPL's multi-baseline polarimetric interferometric UAVSAR data. It presents exemplary results and analyzes the possibilities and limitations of using SAR Tomography and Polarimetric SAR Interferometry (PolInSAR) techniques for the estimation of forest structure. Performance and error indicators for the applicability and reliability of the used multi-baseline (MB) multi-temporal (MT) PolInSAR random volume over ground (RVoG) model are discussed. Experimental results are presented based on JPL's L-band repeat-pass polarimetric interferometric UAVSAR data over temperate and tropical forest biomes in the Harvard Forest, Massachusetts, and in the La Amistad Park, Panama and Costa Rica. The results are partially compared with ground field measurements and with air-borne LVIS lidar data.

  12. Mapping ground surface deformation using temporarily coherent point SAR interferometry: Application to Los Angeles Basin

    Science.gov (United States)

    Zhang, L.; Lu, Zhong; Ding, X.; Jung, H.-S.; Feng, G.; Lee, C.-W.

    2012-01-01

    Multi-temporal interferometric synthetic aperture radar (InSAR) is an effective tool to detect long-term seismotectonic motions by reducing the atmospheric artifacts, thereby providing more precise deformation signal. The commonly used approaches such as persistent scatterer InSAR (PSInSAR) and small baseline subset (SBAS) algorithms need to resolve the phase ambiguities in interferogram stacks either by searching a predefined solution space or by sparse phase unwrapping methods; however the efficiency and the success of phase unwrapping cannot be guaranteed. We present here an alternative approach – temporarily coherent point (TCP) InSAR (TCPInSAR) – to estimate the long term deformation rate without the need of phase unwrapping. The proposed approach has a series of innovations including TCP identification, TCP network and TCP least squares estimator. We apply the proposed method to the Los Angeles Basin in southern California where structurally active faults are believed capable of generating damaging earthquakes. The analysis is based on 55 interferograms from 32 ERS-1/2 images acquired during Oct. 1995 and Dec. 2000. To evaluate the performance of TCPInSAR on a small set of observations, a test with half of interferometric pairs is also performed. The retrieved TCPInSAR measurements have been validated by a comparison with GPS observations from Southern California Integrated GPS Network. Our result presents a similar deformation pattern as shown in past InSAR studies but with a smaller average standard deviation (4.6 mm) compared with GPS observations, indicating that TCPInSAR is a promising alternative for efficiently mapping ground deformation even from a relatively smaller set of interferograms.

  13. 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.

  14. Unsupervised DInSAR processing chain for multi-scale displacement analysis

    Science.gov (United States)

    Casu, Francesco; Manunta, Michele

    2016-04-01

    Earth Observation techniques can be very helpful for the estimation of several sources of ground deformation due to their characteristics of large spatial coverage, high resolution and cost effectiveness. In this scenario, Differential Synthetic Aperture Radar Interferometry (DInSAR) is one of the most effective methodologies for its capability to generate spatially dense deformation maps at both global and local spatial scale, with centimeter to millimeter accuracy. DInSAR exploits the phase difference (interferogram) between SAR image pairs relevant to acquisitions gathered at different times, but with the same illumination geometry and from sufficiently close flight tracks, whose separation is typically referred to as baseline. Among several, the SBAS algorithm is one of the most used DInSAR approaches and it is aimed at generating displacement time series at a multi-scale level by exploiting a set of small baseline interferograms. SBAS, and generally DInSAR, has taken benefit from the large availability of spaceborne SAR data collected along years by several satellite systems, with particular regard to the European ERS and ENVISAT sensors, which have acquired SAR images worldwide during approximately 20 years. Moreover, since 2014 the new generation of Copernicus Sentinel satellites has started to acquire data with a short revisit time (12 days) and a global coverage policy, thus flooding the scientific EO community with an unprecedent amount of data. To efficiently manage such amount of data, proper processing facilities (as those coming from the emerging Cloud Computing technologies) have to be used, as well as novel algorithms aimed at their efficient exploitation have to be developed. In this work we present a set of results achieved by exploiting a recently proposed implementation of the SBAS algorithm, namely Parallel-SBAS (P-SBAS), which allows us to effectively process, in an unsupervised way and in a limited time frame, a huge number of SAR images

  15. A Constellation of CubeSat InSAR Sensors for Rapid-Revisit Surface Deformation Studies

    Science.gov (United States)

    Wye, L.; Lee, S.; Yun, S. H.; Zebker, H. A.; Stock, J. D.; Wicks, C. W., Jr.; Doe, R.

    2016-12-01

    The 2007 NRC Decadal Survey for Earth Sciences highlights three major Earth surface deformation themes: 1) solid-earth hazards and dynamics; 2) human health and security; and 3) land-use change, ecosystem dynamics and biodiversity. Space-based interferometric synthetic aperture radar (InSAR) is a key change detection tool for addressing these themes. Here, we describe the mission and radar payload design for a constellation of S-band InSAR sensors specifically designed to provide the global, high temporal resolution, sub-cm level deformation accuracy needed to address some of the major Earth system goals. InSAR observations with high temporal resolution are needed to properly monitor certain nonlinearly time-varying features (e.g., unstable volcanoes, active fault lines, and heavily-used groundwater or hydrocarbon reservoirs). Good temporal coverage is also needed to reduce atmospheric artifacts by allowing multiple acquisitions to be averaged together, since each individual SAR measurement is corrupted by up to several cm of atmospheric noise. A single InSAR platform is limited in how often it can observe a given scene without sacrificing global spatial coverage. Multiple InSAR platforms provide the spatial-temporal flexibility required to maximize the science return. However, building and launching multiple InSAR platforms is cost-prohibitive for traditional satellites. SRI International (SRI) and our collaborators are working to exploit developments in nanosatellite technology, in particular the emergence of the CubeSat standard, to provide high-cadence InSAR capabilities in an affordable package. The CubeSat Imaging Radar for Earth Science (CIRES) subsystem, a prototype SAR elec­tronics package developed by SRI with support from a 2014 NASA ESTO ACT award, is specifically scaled to be a drop-in radar solution for resource-limited delivery systems like CubeSats and small airborne vehicles. Here, we present our mission concept and flow-down requirements for a

  16. Comparison of four moderate-size earthquakes in southern California using seismology and InSAR

    Science.gov (United States)

    Mellors, R.J.; Magistrale, H.; Earle, P.; Cogbill, A.H.

    2004-01-01

    Source parameters determined from interferometric synthetic aperture radar (InSAR) measurements and from seismic data are compared from four moderate-size (less than M 6) earthquakes in southern California. The goal is to verify approximate detection capabilities of InSAR, assess differences in the results, and test how the two results can be reconciled. First, we calculated the expected surface deformation from all earthquakes greater than magnitude 4 in areas with available InSAR data (347 events). A search for deformation from the events in the interferograms yielded four possible events with magnitudes less than 6. The search for deformation was based on a visual inspection as well as cross-correlation in two dimensions between the measured signal and the expected signal. A grid-search algorithm was then used to estimate focal mechanism and depth from the InSAR data. The results were compared with locations and focal mechanisms from published catalogs. An independent relocation using seismic data was also performed. The seismic locations fell within the area of the expected rupture zone for the three events that show clear surface deformation. Therefore, the technique shows the capability to resolve locations with high accuracy and is applicable worldwide. The depths determined by InSAR agree with well-constrained seismic locations determined in a 3D velocity model. Depth control for well-imaged shallow events using InSAR data is good, and better than the seismic constraints in some cases. A major difficulty for InSAR analysis is the poor temporal coverage of InSAR data, which may make it impossible to distinguish deformation due to different earthquakes at the same location.

  17. SAR-EDU - An education initiative for applied Synthetic Aperture Radar remote sensing

    Science.gov (United States)

    Eckardt, Robert; Richter, Nicole; Auer, Stefan; Eineder, Michael; Roth, Achim; Hajnsek, Irena; Walter, Diana; Braun, Matthias; Motagh, Mahdi; Pathe, Carsten; Pleskachevsky, Andrey; Thiel, Christian; Schmullius, Christiane

    2013-04-01

    Since the 1970s, radar remote sensing techniques have evolved rapidly and are increasingly employed in all fields of earth sciences. Applications are manifold and still expanding due to the continuous development of new instruments and missions as well as the availability of very high-quality data. The trend worldwide is towards operational employment of the various algorithms and methods that have been developed. However, the utilization of operational services does not keep up yet with the rate of technical developments and the improvements in sensor technology. With the enhancing availability and variety of space borne Synthetic Aperture Radar (SAR) data and a growing number of analysis algorithms the need for a vital user community is increasing. Therefore the German Aerospace Center (DLR) together with the Friedrich-Schiller-University Jena (FSU) and the Technical University Munich (TUM) launched the education initiative SAR-EDU. The aim of the project is to facilitate access to expert knowledge in the scientific field of radar remote sensing. Within this effort a web portal will be created to provide seminar material on SAR basics, methods and applications to support both, lecturers and students. The overall intension of the project SAR-EDU is to provide seminar material for higher education in radar remote sensing covering the topic holistically from the very basics to the most advanced methods and applications that are available. The principles of processing and interpreting SAR data are going to be taught using test data sets and open-source as well as commercial software packages. The material that is provided by SAR-EDU will be accessible at no charge from a DLR web portal. The educational tool will have a modular structure, consisting of separate modules that broach the issue of a particular topic. The aim of the implementation of SAR-EDU as application-oriented radar remote sensing educational tool is to advocate the development and wider use of

  18. Leachate From Expanded Polystyrene Cups Is Toxic to Aquatic Invertebrates (Ceriodaphnia dubia

    Directory of Open Access Journals (Sweden)

    Clara Thaysen

    2018-02-01

    Full Text Available Expanded polystyrene (EPS products and their associated chemicals (e.g., styrenes are widespread in the marine environment. As a consequence, bans on their use for single-use packaging materials are being proposed in several municipalities. To better understand how science can inform decision-making, we looked at the available scientific literature about contamination and effects and conducted experiments to measure chemical leachate from polystyrene products and toxicity from the leachate. We conducted leaching experiments with common food matrices (water, soup broth, gravy, black coffee and coffee with cream and sugar at relevant temperatures (70 and 95°C that are consumed in or with several polystyrene products (coffee cup lids, polystyrene stir sticks, polystyrene spoons, EPS cups, EPS bowls, and EPS takeout containers. We analyzed each sample for styrene, ethylbenzene, toluene, benzene, meta- and para- xylene, isopropylbenzene, and isopropyltoluene—chemicals associated with polystyrene products. To determine whether the leachates are toxic, we conducted chronic toxicity tests, measuring survival and reproductive output in Ceriodaphnia dubia. Toxicity tests included nine treatments: seven concentrations of ethylbenzene, EPS cup leachate and a negative control. Overall, we found that temperature has a significant effect on leaching. We only detected leachates in trials conducted at higher temperature −95°C. Ethylbenzene was the only target analyte with final concentrations above the method limit of detection, and was present in the greatest concentrations in EPS and with soup broth. Measurable concentrations of ethylbenzene in the leachate ranged from 1.3 to 3.4 μg/L. In toxicity tests, the calculated LC50 for ethylbenzene was 14 mg/L and the calculated LC20 was 210 μg/L. For the treatment exposed to the EPS cup leachate, mortality was 40%—four times greater than the negative control. Finally, there was no significant difference (p

  19. Correcting Spatial Variance of RCM for GEO SAR Imaging Based on Time-Frequency Scaling

    Science.gov (United States)

    Yu, Ze; Lin, Peng; Xiao, Peng; Kang, Lihong; Li, Chunsheng

    2016-01-01

    Compared with low-Earth orbit synthetic aperture radar (SAR), a geosynchronous (GEO) SAR can have a shorter revisit period and vaster coverage. However, relative motion between this SAR and targets is more complicated, which makes range cell migration (RCM) spatially variant along both range and azimuth. As a result, efficient and precise imaging becomes difficult. This paper analyzes and models spatial variance for GEO SAR in the time and frequency domains. A novel algorithm for GEO SAR imaging with a resolution of 2 m in both the ground cross-range and range directions is proposed, which is composed of five steps. The first is to eliminate linear azimuth variance through the first azimuth time scaling. The second is to achieve RCM correction and range compression. The third is to correct residual azimuth variance by the second azimuth time-frequency scaling. The fourth and final steps are to accomplish azimuth focusing and correct geometric distortion. The most important innovation of this algorithm is implementation of the time-frequency scaling to correct high-order azimuth variance. As demonstrated by simulation results, this algorithm can accomplish GEO SAR imaging with good and uniform imaging quality over the entire swath. PMID:27428974

  20. Rapid Mapping Of Floods Using SAR Data: Opportunities And Critical Aspects

    Science.gov (United States)

    Pulvirenti, Luca; Pierdicca, Nazzareno; Chini, Marco

    2013-04-01

    The potentiality of spaceborne Synthetic Aperture Radar (SAR) for flood mapping was demonstrated by several past investigations. The synoptic view, the capability to operate in almost all-weather conditions and during both day time and night time and the sensitivity of the microwave band to water are the key features that make SAR data useful for monitoring inundation events. In addition, their high spatial resolution, which can reach 1m with the new generation of X-band instruments such as TerraSAR-X and COSMO-SkyMed (CSK), allows emergency managers to use flood maps at very high spatial resolution. CSK gives also the possibility of performing frequent observations of regions hit by floods, thanks to the four-satellite constellation. Current research on flood mapping using SAR is focused on the development of automatic algorithms to be used in near real time applications. The approaches are generally based on the low radar return from smooth open water bodies that behave as specular reflectors and appear dark in SAR images. The major advantage of automatic algorithms is the computational efficiency that makes them suitable for rapid mapping purposes. The choice of the threshold value that, in this kind of algorithms, separates flooded from non-flooded areas is a critical aspect because it depends on the characteristics of the observed scenario and on system parameters. To deal with this aspect an algorithm for automatic detection of the regions of low backscatter has been developed. It basically accomplishes three steps: 1) division of the SAR image in a set of non-overlapping sub-images or splits; 2) selection of inhomogeneous sub-images that contain (at least) two populations of pixels, one of which is formed by dark pixels; 3) the application in sequence of an automatic thresholding algorithm and a region growing algorithm in order to produce a homogeneous map of flooded areas. Besides the aforementioned choice of the threshold, rapid mapping of floods may

  1. 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

  2. The Total Electron Content From InSAR and GNSS: A Midlatitude Study

    DEFF Research Database (Denmark)

    Musico, Elvira; Cesaroni, Claudio; Spogli, Luca

    2018-01-01

    The total electron content (TEC) measured from the interferometric synthetic aperture radar (InSAR) and froma dense network of global navigation satellite system (GNSS) receivers are used to assess the capability of InSAR to retrieve ionospheric information, when the tropospheric contribution...

  3. Ka-Band Digital Beamforming and SweepSAR Demonstration for Ice and Solid Earth Topography

    Science.gov (United States)

    Sadowy, Gregory; Ghaemi, Hirad; Heavy, Brandon; Perkovic, Dragana; Quddus, Momin; Zawadzki, Mark; Moller, Delwyn

    2010-01-01

    GLISTIN is an instrument concept for a single-pass interferometric SAR operating at 35.6 GHz. To achieve large swath widths using practical levels of transmitter power, a digitally-beamformed planar waveguide array is used. This paper describes results from a ground-based demonstration of a 16-receiver prototype. Furthermore, SweepSAR is emerging as promising technique for achieving very wide swaths for surface change detection. NASA and DLR are studying this approach for the DESDynI and Tandem-L missions. SweepSAR employs a reflector with a digitally-beamformed array feed. We will describe development of an airborne demonstration of SweepSAR using the GLISTIN receiver array and a reflector.

  4. 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.

  5. Multi-image Matching of Airborne SAR Imagery by SANCC

    Directory of Open Access Journals (Sweden)

    DING Hao

    2015-03-01

    Full Text Available In order to improve accuracy of SAR matching, a multi-image matching method based on sum of adaptive normalized cross-correlation (SANCC is proposed. It utilizes geometrical and radiometric information of multi-baselinesynthetic aperture radar (SARimages effectively. Firstly, imaging parameters, platform parameters and approximate digital surface model (DSM are used to predict matching line. Secondly, similarity and proximity in Gestalt theory are introduced to SANCC, and SANCC measures of potential matching points along the matching line are calculated. Thirdly, multi-image matching results and object coordinates of matching points are obtained by winner-take-all (WTA optimization strategy. The approach has been demonstrated with airborne SAR images acquired by a Chinese airborne SAR system (CASMSAR system. The experimental results indicate that the proposed algorithm is effective for providing dense and accuracy matching points, reducing the number of mismatches caused by repeated textures, and offering a better solution to match in poor textured areas.

  6. Clinical and epidemiological predictors of transmission in Severe Acute Respiratory Syndrome (SARS

    Directory of Open Access Journals (Sweden)

    Leong Hoe

    2006-10-01

    Full Text Available Abstract Background Only a minority of probable SARS cases caused transmission. We assess if any epidemiological or clinical factors in SARS index patients were associated with increased probability of transmission. Methods We used epidemiological and clinical data on probable SARS patients admitted to Tan Tock Seng Hospital. Using a case-control approach, index patients who had probable SARS who subsequently transmitted the disease to at least one other patient were analysed as "cases" against patients with no transmission as "controls", using multivariate logistic regression analysis. Results 98 index patients were available for analysis (22 with transmission, 76 with no transmission. Covariates positively associated with transmission in univariate analysis at p 650 IU/L (OR 6.4, 23.8 and 4.7 respectively. Conclusion Clinical and epidemiological factors can help us to explain why transmission was observed in some instances but not in others.

  7. Severe acute respiratory syndrome (SARS) in a paediatric cluster in Singapore

    Energy Technology Data Exchange (ETDEWEB)

    Tsou, Ian Y.; Kaw, Gregory J.; Chee, Thomas S. [Department of Diagnostic Radiology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, 308433, Singapore (Singapore); Loh, Lik Eng; Chan, Irene [Department of Paediatric Medicine, KK Women' s and Children' s Hospital, 100 Bukit Timah Road, 229899, Singapore (Singapore)

    2004-01-01

    Severe acute respiratory syndrome (SARS) is a major infectious disease pandemic that occurred in early 2003, and one of the diagnostic criteria is the presence of chest radiographic findings. To describe the radiographic features of SARS in a cluster of affected children. The chest radiographs of four related children ranging in age from 18 months to 9 years diagnosed as having SARS were reviewed for the presence of air-space shadowing, air bronchograms, peribronchial thickening, interstitial disease, pleural effusion, pneumothorax, hilar lymphadenopathy and mediastinal widening. Ill-defined air-space shadowing was the common finding in all the children. The distribution was unifocal or multifocal. No other findings were seen on the radiographs. None of the children developed radiographic findings consistent with acute respiratory distress syndrome. All four children showed significant resolution of the radiographic findings 4-6 days after the initial radiograph. Early recognition of these features is important in implementing isolation and containment measures to prevent the spread of infection. SARS in children appears to manifest as a milder form of the disease as compared to adults. (orig.)

  8. Complex surface deformation of Akutan volcano, Alaska revealed from InSAR time series

    Science.gov (United States)

    Wang, Teng; DeGrandpre, Kimberly; Lu, Zhong; Freymueller, Jeffrey T.

    2018-02-01

    Akutan volcano is one of the most active volcanoes in the Aleutian arc. An intense swarm of volcano-tectonic earthquakes occurred across the island in 1996. Surface deformation after the 1996 earthquake sequence has been studied using Interferometric Synthetic Aperture Radar (InSAR), yet it is hard to determine the detailed temporal behavior and spatial extent of the deformation due to decorrelation and the sparse temporal sampling of SAR data. Atmospheric delay anomalies over Akutan volcano are also strong, bringing additional technical challenges. Here we present a time series InSAR analysis from 2003 to 2016 to reveal the surface deformation in more detail. Four tracks of Envisat data acquired from 2003 to 2010 and one track of TerraSAR-X data acquired from 2010 to 2016 are processed to produce high-resolution surface deformation, with a focus on studying two transient episodes of inflation in 2008 and 2014. For the TerraSAR-X data, the atmospheric delay is estimated and removed using the common-master stacking method. These derived deformation maps show a consistently uplifting area on the northeastern flank of the volcano. From the TerraSAR-X data, we quantify the velocity of the subsidence inside the caldera to be as high as 10 mm/year, and identify another subsidence area near the ground cracks created during the 1996 swarm.

  9. C/X-band SAR interferometry applied to ground monitoring: examples and new potential

    Science.gov (United States)

    Nutricato, Raffaele; Nitti, Davide O.; Bovenga, Fabio; Refice, Alberto; Wasowski, Janusz; Chiaradia, Maria T.

    2013-10-01

    Classical applications of the MTInSAR techniques have been carried out in the past on medium resolution data acquired by the ERS, Envisat (ENV) and Radarsat sensors. The new generation of high-resolution X-Band SAR sensors, such as TerraSAR-X (TSX) and the COSMO-SkyMed (CSK) constellation allows acquiring data with spatial resolution reaching metric/submetric values. Thanks to the finer spatial resolution with respect to C-band data, X-band InSAR applications result very promising for monitoring single man-made structures (buildings, bridges, railways and highways), as well as landslides. This is particularly relevant where C-band data show low density of coherent scatterers. Moreover, thanks again to the higher resolution, it is possible to infer reliable estimates of the displacement rates with a number of SAR scenes significantly lower than in C-band within the same time span or by using more images acquired in a narrower time span. We present examples of the application of a Persistent Scatterers Interferometry technique, namely the SPINUA algorithm, to data acquired by ENV, TSX and CSK on selected number of sites. Different cases are considered concerning monitoring of both instable slopes and infrastructure. Results are compared and commented with particular attention paid to the advantages provided by the new generation of X-band high resolution space-borne SAR sensors.

  10. Monitoring Line-Infrastructure With Multisensor SAR Interferometry : Products and Performance Assessment Metrics

    NARCIS (Netherlands)

    Chang, L.; Dollevoet, R.P.B.J.; Hanssen, R.F.

    2018-01-01

    Satellite radar interferometry (InSAR) is an emerging technique to monitor the stability and health of line-infrastructure assets, such as railways, dams, and pipelines. However, InSAR is an opportunistic approach as the location and occurrence of its measurements (coherent scatterers) cannot be

  11. A SAR Observation and Numerical Study on Ocean Surface Imprints of Atmospheric Vortex Streets

    Directory of Open Access Journals (Sweden)

    William G. Pichel

    2008-05-01

    Full Text Available The sea surface imprints of Atmospheric Vortex Street (AVS off Aleutian Volcanic Islands, Alaska were observed in two RADARSAT-1 Synthetic Aperture Radar (SAR images separated by about 11 hours. In both images, three pairs of distinctive vortices shedding in the lee side of two volcanic mountains can be clearly seen. The length and width of the vortex street are about 60-70 km and 20 km, respectively. Although the AVS’s in the two SAR images have similar shapes, the structure of vortices within the AVS is highly asymmetrical. The sea surface wind speed is estimated from the SAR images with wind direction input from Navy NOGAPS model. In this paper we present a complete MM5 model simulation of the observed AVS. The surface wind simulated from the MM5 model is in good agreement with SAR-derived wind. The vortex shedding rate calculated from the model run is about 1 hour and 50 minutes. Other basic characteristics of the AVS including propagation speed of the vortex, Strouhal and Reynolds numbers favorable for AVS generation are also derived. The wind associated with AVS modifies the cloud structure in the marine atmospheric boundary layer. The AVS cloud pattern is also observed on a MODIS visible band image taken between the two RADARSAT SAR images. An ENVISAT advance SAR image taken 4 hours after the second RADARSAT SAR image shows that the AVS has almost vanished.

  12. A mouse-adapted SARS-coronavirus causes disease and mortality in BALB/c mice.

    Directory of Open Access Journals (Sweden)

    Anjeanette Roberts

    2007-01-01

    Full Text Available No single animal model for severe acute respiratory syndrome (SARS reproduces all aspects of the human disease. Young inbred mice support SARS-coronavirus (SARS-CoV replication in the respiratory tract and are available in sufficient numbers for statistical evaluation. They are relatively inexpensive and easily accessible, but their use in SARS research is limited because they do not develop illness following infection. Older (12- to 14-mo-old BALB/c mice develop clinical illness and pneumonitis, but they can be hard to procure, and immune senescence complicates pathogenesis studies. We adapted the SARS-CoV (Urbani strain by serial passage in the respiratory tract of young BALB/c mice. Fifteen passages resulted in a virus (MA15 that is lethal for mice following intranasal inoculation. Lethality is preceded by rapid and high titer viral replication in lungs, viremia, and dissemination of virus to extrapulmonary sites accompanied by lymphopenia, neutrophilia, and pathological changes in the lungs. Abundant viral antigen is extensively distributed in bronchial epithelial cells and alveolar pneumocytes, and necrotic cellular debris is present in airways and alveoli, with only mild and focal pneumonitis. These observations suggest that mice infected with MA15 die from an overwhelming viral infection with extensive, virally mediated destruction of pneumocytes and ciliated epithelial cells. The MA15 virus has six coding mutations associated with adaptation and increased virulence; when introduced into a recombinant SARS-CoV, these mutations result in a highly virulent and lethal virus (rMA15, duplicating the phenotype of the biologically derived MA15 virus. Intranasal inoculation with MA15 reproduces many aspects of disease seen in severe human cases of SARS. The availability of the MA15 virus will enhance the use of the mouse model for SARS because infection with MA15 causes morbidity, mortality, and pulmonary pathology. This virus will be of value as

  13. Advanced Corrections for InSAR Using GPS and Numerical Weather Models

    Science.gov (United States)

    Cossu, F.; Foster, J. H.; Amelung, F.; Varugu, B. K.; Businger, S.; Cherubini, T.

    2017-12-01

    We present results from an investigation into the application of numerical weather models for generating tropospheric correction fields for Interferometric Synthetic Aperture Radar (InSAR). We apply the technique to data acquired from a UAVSAR campaign as well as from the CosmoSkyMed satellites. The complex spatial and temporal changes in the atmospheric propagation delay of the radar signal remain the single biggest factor limiting InSAR's potential for hazard monitoring and mitigation. A new generation of InSAR systems is being built and launched, and optimizing the science and hazard applications of these systems requires advanced methodologies to mitigate tropospheric noise. We use the Weather Research and Forecasting (WRF) model to generate a 900 m spatial resolution atmospheric models covering the Big Island of Hawaii and an even higher, 300 m resolution grid over the Mauna Loa and Kilauea volcanoes. By comparing a range of approaches, from the simplest, using reanalyses based on typically available meteorological observations, through to the "kitchen-sink" approach of assimilating all relevant data sets into our custom analyses, we examine the impact of the additional data sets on the atmospheric models and their effectiveness in correcting InSAR data. We focus particularly on the assimilation of information from the more than 60 GPS sites in the island. We ingest zenith tropospheric delay estimates from these sites directly into the WRF analyses, and also perform double-difference tomography using the phase residuals from the GPS processing to robustly incorporate heterogeneous information from the GPS data into the atmospheric models. We assess our performance through comparisons of our atmospheric models with external observations not ingested into the model, and through the effectiveness of the derived phase screens in reducing InSAR variance. Comparison of the InSAR data, our atmospheric analyses, and assessments of the active local and mesoscale

  14. Mechanisms of the electron density depletion in the SAR arc region

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    1996-02-01

    Full Text Available This study compares the measurements of electron density and temperature and the integral airglow intensity at 630 nm in the SAR arc region and slightly south of this (obtained by the Isis 2 spacecraft during the 18 December 1971 magnetic storm, with the model results obtained using the time dependent one-dimensional mathematical model of the Earth\\'s ionosphere and plasmasphere. The explicit expression in the third Enskog approximation for the electron thermal conductivity coefficient in the multicomponent mixture of ionized gases and a simplified calculation method for this coefficient presents an opportunity to calculate more exactly the electron temperature and density and 630 nm emission within SAR arc region are used in the model. Collisions between N2 and hot thermal electrons in the SAR arc region produce vibrationally excited nitrogen molecules. It appears that the loss rate of O+(4S due to reactions with the vibrationally excited nitrogen is enough to explain electron density depression by a factor of two at F-region heights and the topside ionosphere density variations within the SAR arc if the erosion of plasma within geomagnetic field tubes, during the main phase of the geomagnetic storm and subsequent filling of geomagnetic tubes during the recovery phase, are considered. To explain the disagreement by a factor 1.5 between the observed and modeled SAR arc electron densities an additional plasma drift velocity ~–30 m s–1 in the ion continuity equations is needed during the recovery phase. This additional plasma drift velocity is likely caused by the transition from convecting to corotating flux tubes on the equatorward wall of the trough. The electron densities and temperatures and 630 nm integral intensity at the SAR arc and slightly south of this region as measured for the 18 December 1971 magnetic storm were correctly described by the model without perpendicular electric fields. Within this model framework the effect of the

  15. SARS and population health technology.

    Science.gov (United States)

    Eysenbach, Gunther

    2003-01-01

    The recent global outbreak of SARS (severe acute respiratory syndrome) provides an opportunity to study the use and impact of public health informatics and population health technology to detect and fight a global epidemic. Population health technology is the umbrella term for technology applications that have a population focus and the potential to improve public health. This includes the Internet, but also other technologies such as wireless devices, mobile phones, smart appliances, or smart homes. In the context of an outbreak or bioterrorism attack, such technologies may help to gather intelligence and detect diseases early, and communicate and exchange information electronically worldwide. Some of the technologies brought forward during the SARS epidemic may have been primarily motivated by marketing efforts, or were more directed towards reassuring people that "something is being done," ie, fighting an "epidemic of fear." To understand "fear epidemiology" is important because early warning systems monitoring data from a large number of people may not be able to discriminate between a biological epidemic and an epidemic of fear. The need for critical evaluation of all of these technologies is stressed.

  16. Using Satellite SAR to Characterize the Wind Flow around Offshore Wind Farms

    Directory of Open Access Journals (Sweden)

    Charlotte Bay Hasager

    2015-06-01

    Full Text Available Offshore wind farm cluster effects between neighboring wind farms increase rapidly with the large-scale deployment of offshore wind turbines. The wind farm wakes observed from Synthetic Aperture Radar (SAR are sometimes visible and atmospheric and wake models are here shown to convincingly reproduce the observed very long wind farm wakes. The present study mainly focuses on wind farm wake climatology based on Envisat ASAR. The available SAR data archive covering the large offshore wind farms at Horns Rev has been used for geo-located wind farm wake studies. However, the results are difficult to interpret due to mainly three issues: the limited number of samples per wind directional sector, the coastal wind speed gradient, and oceanic bathymetry effects in the SAR retrievals. A new methodology is developed and presented. This method overcomes effectively the first issue and in most cases, but not always, the second. In the new method all wind field maps are rotated such that the wind is always coming from the same relative direction. By applying the new method to the SAR wind maps, mesoscale and microscale model wake aggregated wind-fields results are compared. The SAR-based findings strongly support the model results at Horns Rev 1.

  17. Impact of Microplastic Beads and Fibers on Waterflea (Ceriodaphnia dubia) Survival, Growth, and Reproduction: Implications of Single and Mixture Exposures.

    Science.gov (United States)

    Ziajahromi, Shima; Kumar, Anupama; Neale, Peta A; Leusch, Frederic D L

    2017-11-21

    There is limited knowledge regarding the adverse effects of wastewater-derived microplastics, particularly fibers, on aquatic biota. In this study, we examined the acute (48 h) and chronic (8 d) effects of microplastic polyester fibers and polyethylene (PE) beads on freshwater zooplankton Ceriodaphnia dubia. We also assessed the acute response of C. dubia to a binary mixture of microplastic beads and fibers for the first time. Acute exposure to fibers and PE beads both showed a dose-dependent effect on survival. An equitoxic binary mixture of beads and fibers resulted in a toxic unit of 1.85 indicating less than additive effects. Chronic exposure to lower concentrations did not significantly affect survival of C. dubia, but a dose-dependent effect on growth and reproduction was observed. Fibers showed greater adverse effects than PE beads. While ingestion of fibers was not observed, scanning electron microscopy showed carapace and antenna deformities after exposure to fibers, with no deformities observed after exposure to PE beads. While much of the current research has focused on microplastic beads, our study shows that microplastic fibers pose a greater risk to C. dubia, with reduced reproductive output observed at concentrations within an order of magnitude of reported environmental levels.

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

    Science.gov (United States)

    Kim, Sungho; Song, Woo-Jin; Kim, So-Hyun

    2016-01-01

    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 database generated

  19. 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

  20. SAR target recognition using behaviour library of different shapes in different incidence angles and polarisations

    Science.gov (United States)

    Fallahpour, Mojtaba Behzad; Dehghani, Hamid; Jabbar Rashidi, Ali; Sheikhi, Abbas

    2018-05-01

    Target recognition is one of the most important issues in the interpretation of the synthetic aperture radar (SAR) images. Modelling, analysis, and recognition of the effects of influential parameters in the SAR can provide a better understanding of the SAR imaging systems, and therefore facilitates the interpretation of the produced images. Influential parameters in SAR images can be divided into five general categories of radar, radar platform, channel, imaging region, and processing section, each of which has different physical, structural, hardware, and software sub-parameters with clear roles in the finally formed images. In this paper, for the first time, a behaviour library that includes the effects of polarisation, incidence angle, and shape of targets, as radar and imaging region sub-parameters, in the SAR images are extracted. This library shows that the created pattern for each of cylindrical, conical, and cubic shapes is unique, and due to their unique properties these types of shapes can be recognised in the SAR images. This capability is applied to data acquired with the Canadian RADARSAT1 satellite.

  1. Accelerating Spaceborne SAR Imaging Using Multiple CPU/GPU Deep Collaborative Computing

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    2016-04-01

    Full Text Available With the development of synthetic aperture radar (SAR technologies in recent years, the huge amount of remote sensing data brings challenges for real-time imaging processing. Therefore, high performance computing (HPC methods have been presented to accelerate SAR imaging, especially the GPU based methods. In the classical GPU based imaging algorithm, GPU is employed to accelerate image processing by massive parallel computing, and CPU is only used to perform the auxiliary work such as data input/output (IO. 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. Through the proposed tasks partitioning and scheduling strategy, the whole image can be generated with deep collaborative multiple CPU/GPU computing. In the part of CPU parallel imaging, the advanced vector extension (AVX method is firstly introduced into the multi-core CPU parallel method for higher efficiency. As for the GPU parallel imaging, not only the bottlenecks of memory limitation and frequent data transferring are broken, but also kinds of optimized strategies are applied, such as streaming, parallel pipeline and so on. Experimental results demonstrate that the deep CPU/GPU collaborative imaging method enhances the efficiency of SAR imaging on single-core CPU by 270 times and realizes the real-time imaging in that the imaging rate outperforms the raw data generation rate.

  2. Accelerating Spaceborne SAR Imaging Using Multiple CPU/GPU Deep Collaborative Computing.

    Science.gov (United States)

    Zhang, Fan; Li, Guojun; Li, Wei; Hu, Wei; Hu, Yuxin

    2016-04-07

    With the development of synthetic aperture radar (SAR) technologies in recent years, the huge amount of remote sensing data brings challenges for real-time imaging processing. Therefore, high performance computing (HPC) methods have been presented to accelerate SAR imaging, especially the GPU based methods. In the classical GPU based imaging algorithm, GPU is employed to accelerate image processing by massive parallel computing, and CPU is only used to perform the auxiliary work such as data input/output (IO). 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. Through the proposed tasks partitioning and scheduling strategy, the whole image can be generated with deep collaborative multiple CPU/GPU computing. In the part of CPU parallel imaging, the advanced vector extension (AVX) method is firstly introduced into the multi-core CPU parallel method for higher efficiency. As for the GPU parallel imaging, not only the bottlenecks of memory limitation and frequent data transferring are broken, but also kinds of optimized strategies are applied, such as streaming, parallel pipeline and so on. Experimental results demonstrate that the deep CPU/GPU collaborative imaging method enhances the efficiency of SAR imaging on single-core CPU by 270 times and realizes the real-time imaging in that the imaging rate outperforms the raw data generation rate.

  3. Multi-temporal InSAR Datastacks for Surface Deformation Monitoring: a Review

    Science.gov (United States)

    Ferretti, A.; Novali, F.; Prati, C.; Rocca, F.

    2009-04-01

    In the last decade extensive processing of thousands of satellite radar scenes acquired by different sensors (e.g. ERS-1/2, ENVISAT and RADARSAT) has demonstrated how multi-temporal data-sets can be successfully exploited for surface deformation monitoring, by identifying objects on the terrain that have a stable, point-like behaviour. These objects, referred to as Permanent or Persistent Scatterers (PS), can be geo-coded and monitored for movement very accurately, acting as a "natural" geodetic network, integrating successfully continuous GPS data. After a brief analysis of both advantages and drawbacks of InSAR datastacks, the paper presents examples of applications of PS measurements for detecting and monitoring active faults, aquifers and oil/gas reservoirs, using experience in Europe, North America and Japan, and concludes with a discussion on future directions for PSInSAR analysis. Special attention is paid to the possibility of creating deformation maps over wide areas using historical archives of data already available. This second part of the paper will briefly discuss the technical features of the new radar sensors recently launched (namely: TerraSAR-X, RADARSAT-2, and CosmoSkyMed) and their impact on space geodesy, highlighting the importance of data continuity and standardized acquisition policies for almost all InSAR and PSInSAR applications. Finally, recent advances in the algorithms applied in PS analysis, such as detection of "temporary PS", PS characterization and exploitation of distributed scatterers, will be briefly discussed based on the processing of real data.

  4. A Novel Sidelobe Reduction Algorithm Based on Two-Dimensional Sidelobe Correction Using D-SVA for Squint SAR Images

    Directory of Open Access Journals (Sweden)

    Min Liu

    2018-03-01

    Full Text Available Sidelobe reduction is a very primary task for synthetic aperture radar (SAR images. Various methods have been proposed for broadside SAR, which can suppress the sidelobes effectively while maintaining high image resolution at the same time. Alternatively, squint SAR, especially highly squint SAR, has emerged as an important tool that provides more mobility and flexibility and has become a focus of recent research studies. One of the research challenges for squint SAR is how to resolve the severe range-azimuth coupling of echo signals. Unlike broadside SAR images, the range and azimuth sidelobes of the squint SAR images no longer locate on the principal axes with high probability. Thus the spatially variant apodization (SVA filters could hardly get all the sidelobe information, and hence the sidelobe reduction process is not optimal. In this paper, we present an improved algorithm called double spatially variant apodization (D-SVA for better sidelobe suppression. Satisfactory sidelobe reduction results are achieved with the proposed algorithm by comparing the squint SAR images to the broadside SAR images. Simulation results also demonstrate the reliability and efficiency of the proposed method.

  5. Assessment of induced SAR in children exposed to electromagnetic plane waves between 10 MHz and 5.6 GHz

    International Nuclear Information System (INIS)

    Bakker, J F; Paulides, M M; Van Rhoon, G C; Christ, A; Kuster, N

    2010-01-01

    To avoid potentially adverse health effects of electromagnetic fields (EMF), the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has defined EMF reference levels from the basic restrictions on the induced whole-body-averaged specific absorption rate (SAR wb ) and the peak 10 g spatial-averaged SAR (SAR 10g ). The objective of this study is to assess if the SAR in children remains below the basic restrictions upon exposure at the reference levels. Finite difference time domain (FDTD) modeling was used to calculate the SAR in six children and two adults when exposed to all 12 orthogonal plane wave configurations. A sensitivity study showed an expanded uncertainty of 53% (SAR wb ) and 58% (SAR 10g ) due to variations in simulation settings and tissue properties. In this study, we found that the basic restriction on the SAR wb is occasionally exceeded for children, up to a maximum of 45% in small children. The maximum SAR 10g values, usually found at body protrusions, remain under the limit for all scenarios studied. Our results are in good agreement with the literature, suggesting that the recommended ICNIRP reference levels may need fine tuning.

  6. Assessment of induced SAR in children exposed to electromagnetic plane waves between 10 MHz and 5.6 GHz

    Energy Technology Data Exchange (ETDEWEB)

    Bakker, J F; Paulides, M M; Van Rhoon, G C [Erasmus MC-Daniel den Hoed Cancer Center, Department of Radiation Oncology, Section Hyperthermia, PO box 5201, NL-3008 AE, Rotterdam (Netherlands); Christ, A; Kuster, N, E-mail: j.bakker@erasmusmc.n [Foundation for Research on Information Technologies in Society (IT' IS) (Switzerland)

    2010-06-07

    To avoid potentially adverse health effects of electromagnetic fields (EMF), the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has defined EMF reference levels from the basic restrictions on the induced whole-body-averaged specific absorption rate (SAR{sub wb}) and the peak 10 g spatial-averaged SAR (SAR{sub 10g}). The objective of this study is to assess if the SAR in children remains below the basic restrictions upon exposure at the reference levels. Finite difference time domain (FDTD) modeling was used to calculate the SAR in six children and two adults when exposed to all 12 orthogonal plane wave configurations. A sensitivity study showed an expanded uncertainty of 53% (SAR{sub wb}) and 58% (SAR{sub 10g}) due to variations in simulation settings and tissue properties. In this study, we found that the basic restriction on the SAR{sub wb} is occasionally exceeded for children, up to a maximum of 45% in small children. The maximum SAR{sub 10g} values, usually found at body protrusions, remain under the limit for all scenarios studied. Our results are in good agreement with the literature, suggesting that the recommended ICNIRP reference levels may need fine tuning.

  7. Silencing of SARS-CoV spike gene by small interfering RNA in HEK 293T cells

    International Nuclear Information System (INIS)

    Qin Zhaoling; Zhao Ping; Zhang Xiaolian; Yu Jianguo; Cao Mingmei; Zhao Lanjuan; Luan Jie; Qi Zhongtian

    2004-01-01

    Two candidate small interfering RNAs (siRNAs) corresponding to severe acute respiratory syndrome-associated coronavirus (SARS-CoV) spike gene were designed and in vitro transcribed to explore the possibility of silencing SARS-CoV S gene. The plasmid pEGFP-optS, which contains the codon-optimized SARS-CoV S gene and expresses spike-EGFP fusion protein (S-EGFP) as silencing target and expressing reporter, was transfected with siRNAs into HEK 293T cells. At various time points of posttransfection, the levels of S-EGFP expression and amounts of spike mRNA transcript were detected by fluorescence microscopy, flow cytometry, Western blot, and real-time quantitative PCR, respectively. The results showed that the cells transfected with pEGFP-optS expressed S-EGFP fusion protein at a higher level compared with those transfected with pEGFP-S, which contains wildtype SARS-CoV spike gene sequence. The green fluorescence, mean fluorescence intensity, and SARS-CoV S RNA transcripts were found significantly reduced, and the expression of SARS-CoV S glycoprotein was strongly inhibited in those cells co-transfected with either EGFP- or S-specific siRNAs. Our findings demonstrated that the S-specific siRNAs used in this study were able to specifically and effectively inhibit SARS-CoV S glycoprotein expression in cultured cells through blocking the accumulation of S mRNA, which may provide an approach for studies on the functions of SARS-CoV S gene and development of novel prophylactic or therapeutic agents for SARS-CoV

  8. Non-Cooperative Bistatic SAR Clock Drift Compensation for Tomographic Acquisitions

    Directory of Open Access Journals (Sweden)

    Mario Azcueta

    2017-10-01

    Full Text Available In the last years, an important amount of research has been headed towards the measurement of above-ground forest biomass with polarimetric Synthetic Aperture Radar (SAR tomography techniques. This has motivated the proposal of future bistatic SAR missions, like the recent non-cooperative SAOCOM-CS and PARSIFAL from CONAE and ESA. It is well known that the quality of SAR tomography is directly related to the phase accuracy of the interferometer that, in the case of non-cooperative systems, can be particularly affected by the relative drift between onboard clocks. In this letter, we provide insight on the impact of the clock drift error on bistatic interferometry, as well as propose a correction algorithm to compensate its effect. The accuracy of the compensation is tested on simulated acquisitions over volumetric targets, estimating the final impact on tomographic profiles.

  9. Monitoring the Sumatra volcanic arc with InSAR

    Science.gov (United States)

    Chaussard, E.; Hong, S.; Amelung, F.

    2009-12-01

    The Sumatra volcanic arc is the result of the subduction of the Indo-Australian plate under the Sunda plate. The arc consists of 35 known volcanic centers, subaerials on the west coast of the Sumatra and Andaman Islands and submarines between these islands. Six active centers are known in the Sumatra volcanic arc. Surface deformation in volcanic areas usually indicates movement of magma or hydrothermal fluids at depth. Here we present a satellite-based Interferometric synthetic aperture radar (InSAR) survey of the Sumatra volcanic arc using ALOS data. Spanning the years 2007 to beginning of 2009, our survey reveals the background level of activity of the 35 volcanoes. We processed data from 40 tracks (24 in descending orbit and 16 in ascending orbit) to cover the whole Sumatra arc. In the first results five of these six known active centers show no sign of activity: Dempo, Kaba, Marapi, Talang and Peuet. The remaining active volcano, Mount Kerinci, has an ambiguous signal. We used pair-wise logic and InSAR time series of the available ALOS data to determine if the observed InSAR signal is caused by ground deformation or by atmospheric delays.

  10. Multifrequency OFDM SAR in Presence of Deception Jamming

    Directory of Open Access Journals (Sweden)

    Schuerger Jonathan

    2010-01-01

    Full Text Available Orthogonal frequency division multiplexing (OFDM is considered in this paper from the perspective of usage in imaging radar scenarios with deception jamming. OFDM radar signals are inherently multifrequency waveforms, composed of a number of subbands which are orthogonal to each other. While being employed extensively in communications, OFDM has not found comparatively wide use in radar, and, particularly, in synthetic aperture radar (SAR applications. In this paper, we aim to show the advantages of OFDM-coded radar signals with random subband composition when used in deception jamming scenarios. Two approaches to create a radar signal by the jammer are considered: instantaneous frequency (IF estimator and digital-RF-memory- (DRFM- based reproducer. In both cases, the jammer aims to create a copy of a valid target image via resending the radar signal at prescribed time intervals. Jammer signals are derived and used in SAR simulations with three types of signal models: OFDM, linear frequency modulated (LFM, and frequency-hopped (FH. Presented results include simulated peak side lobe (PSL and peak cross-correlation values for random OFDM signals, as well as simulated SAR imagery with IF and DRFM jammers'-induced false targets.

  11. There is no one-size-fits-all product for InSAR; on the inclusion of contextual information for geodetically-proof InSAR data products

    Science.gov (United States)

    Hanssen, R. F.

    2017-12-01

    In traditional geodesy, one is interested in determining the coordinates, or the change in coordinates, of predefined benchmarks. These benchmarks are clearly identifiable and are especially established to be representative of the signal of interest. This holds, e.g., for leveling benchmarks, for triangulation/trilateration benchmarks, and for GNSS benchmarks. The desired coordinates are not identical to the basic measurements, and need to be estimated using robust estimation procedures, where the stochastic nature of the measurements is taken into account. For InSAR, however, the `benchmarks' are not predefined. In fact, usually we do not know where an effective benchmark is located, even though we can determine its dynamic behavior pretty well. This poses several significant problems. First, we cannot describe the quality of the measurements, unless we already know the dynamic behavior of the benchmark. Second, if we don't know the quality of the measurements, we cannot compute the quality of the estimated parameters. Third, rather harsh assumptions need to be made to produce a result. These (usually implicit) assumptions differ between processing operators and the used software, and are severely affected by the amount of available data. Fourth, the `relative' nature of the final estimates is usually not explicitly stated, which is particularly problematic for non-expert users. Finally, whereas conventional geodesy applies rigorous testing to check for measurement or model errors, this is hardly ever done in InSAR-geodesy. These problems make it rather impossible to provide a precise, reliable, repeatable, and `universal' InSAR product or service. Here we evaluate the requirements and challenges to move towards InSAR as a geodetically-proof product. In particular this involves the explicit inclusion of contextual information, as well as InSAR procedures, standards and a technical protocol, supported by the International Association of Geodesy and the

  12. Effects of Target Positioning Error on Motion Compensation for Airborne Interferometric SAR

    Directory of Open Access Journals (Sweden)

    Li Yin-wei

    2013-12-01

    Full Text Available The measurement inaccuracies of Inertial Measurement Unit/Global Positioning System (IMU/GPS as well as the positioning error of the target may contribute to the residual uncompensated motion errors in the MOtion COmpensation (MOCO approach based on the measurement of IMU/GPS. Aiming at the effects of target positioning error on MOCO for airborne interferometric SAR, the paper firstly deduces a mathematical model of residual motion error bring out by target positioning error under the condition of squint. And the paper analyzes the effects on the residual motion error caused by system sampling delay error, the Doppler center frequency error and reference DEM error which result in target positioning error based on the model. Then, the paper discusses the effects of the reference DEM error on the interferometric SAR image quality, the interferometric phase and the coherent coefficient. The research provides theoretical bases for the MOCO precision in signal processing of airborne high precision SAR and airborne repeat-pass interferometric SAR.

  13. The Performance Analysis Based on SAR Sample Covariance Matrix

    Directory of Open Access Journals (Sweden)

    Esra Erten

    2012-03-01

    Full Text Available Multi-channel systems appear in several fields of application in science. In the Synthetic Aperture Radar (SAR context, multi-channel systems may refer to different domains, as multi-polarization, multi-interferometric or multi-temporal data, or even a combination of them. Due to the inherent speckle phenomenon present in SAR images, the statistical description of the data is almost mandatory for its utilization. The complex images acquired over natural media present in general zero-mean circular Gaussian characteristics. In this case, second order statistics as the multi-channel covariance matrix fully describe the data. For practical situations however, the covariance matrix has to be estimated using a limited number of samples, and this sample covariance matrix follow the complex Wishart distribution. In this context, the eigendecomposition of the multi-channel covariance matrix has been shown in different areas of high relevance regarding the physical properties of the imaged scene. Specifically, the maximum eigenvalue of the covariance matrix has been frequently used in different applications as target or change detection, estimation of the dominant scattering mechanism in polarimetric data, moving target indication, etc. In this paper, the statistical behavior of the maximum eigenvalue derived from the eigendecomposition of the sample multi-channel covariance matrix in terms of multi-channel SAR images is simplified for SAR community. Validation is performed against simulated data and examples of estimation and detection problems using the analytical expressions are as well given.

  14. Investigation of Slow-Moving Landslides from ALOS/PALSAR Images with TCPInSAR: A Case Study of Oso, USA

    Directory of Open Access Journals (Sweden)

    Qian Sun

    2014-12-01

    Full Text Available Monitoring slope instability is of great significance for understanding landslide kinematics and, therefore, reducing the related geological hazards. In recent years, interferometric synthetic aperture radar (InSAR has been widely applied to this end, especially thanks to the prompt evolution of multi-temporal InSAR (MTInSAR algorithms. In this paper, temporarily-coherent point InSAR (TCPInSAR, a recently-developed MTInSAR technique, is employed to investigate the slow-moving landslides in Oso, U.S., with 13 ALOS/PALSAR images. Compared to other MTInSAR techniques, TCPInSAR can work well with a small amount of data and is immune to unwrapping errors. Furthermore, the severe orbital ramps emanated from the inaccurate determination of the ALOS satellite’s state vector can be jointly estimated by TCPInSAR, resulting in an exhaustive separation between the orbital errors and displacement signals. The TCPInSAR-derived deformation map indicates that the riverside slopes adjacent to the North Fork of the Stillaguamish River, where the 2014 mudslide occurred, were active during 2007 and 2011. Besides, Coal Mountain has been found to be experiencing slow-moving landslides with clear boundaries and considerable magnitudes. The Deer Creek River is also threatened by a potential landslide dam due to the creeps detected in a nearby slope. The slope instability information revealed in this study is helpful to deal with the landslide hazards in Oso.

  15. Chandrayaan-2 dual-frequency SAR: Further investigation into lunar water and regolith

    Science.gov (United States)

    Putrevu, Deepak; Das, Anup; Vachhani, J. G.; Trivedi, Sanjay; Misra, Tapan

    2016-01-01

    The Space Applications Centre (SAC), one of the major centers of the Indian Space Research Organization (ISRO), is developing a high resolution, dual-frequency Synthetic Aperture Radar as a science payload on Chandrayaan-2, ISRO's second moon mission. With this instrument, ISRO aims to further the ongoing studies of the data from S-band MiniSAR onboard Chandrayaan-1 (India) and the MiniRF of Lunar Reconnaissance Orbiter (USA). The SAR instrument has been configured to operate with both L- and S-bands, sharing a common antenna. The S-band SAR will provide continuity to the MiniSAR data, whereas L-band is expected to provide deeper penetration of the lunar regolith. The system will have a selectable slant-range resolution from 2 m to 75 m, along with standalone (L or S) and simultaneous (L and S) modes of imaging. Various features of the instrument like hybrid and full-polarimetry, a wide range of imaging incidence angles (∼10° to ∼35°) and the high spatial resolution will greatly enhance our understanding of surface properties especially in the polar regions of the Moon. The system will also help in resolving some of the ambiguities in interpreting high values of Circular Polarization Ratio (CPR) observed in MiniSAR data. The added information from full-polarimetric data will allow greater confidence in the results derived particularly in detecting the presence (and estimating the quantity) of water-ice in the polar craters. Being a planetary mission, the L&S-band SAR for Chandrayaan-2 faced stringent limits on mass, power and data rate (15 kg, 100 W and 160 Mbps respectively), irrespective of any of the planned modes of operation. This necessitated large-scale miniaturization, extensive use of on-board processing, and devices and techniques to conserve power. This paper discusses the scientific objectives which drive the requirement of a lunar SAR mission and presents the configuration of the instrument, along with a description of a number of features of the

  16. Eutelsat 2: SAR-10009 nickel-hydrogen battery

    Science.gov (United States)

    Miller, Lee

    1991-01-01

    The topics are presented in viewgraph form and include SAR-10009 design features, specific energy, analyses and testing, redundant structural insulation, electronics, corrosion protection, battery cell life cycle tests, and spacecraft launches.

  17. Confirmation of quasi-static approximation in SAR evaluation for a wireless power transfer system.

    Science.gov (United States)

    Hirata, Akimasa; Ito, Fumihiro; Laakso, Ilkka

    2013-09-07

    The present study discusses the applicability of the magneto-quasi-static approximation to the calculation of the specific absorption rate (SAR) in a cylindrical model for a wireless power transfer system. Resonant coils with different parameters were considered in the 10 MHz band. A two-step quasi-static method that is comprised of the method of moments and the scalar-potential finite-difference methods is applied, which can consider the effects of electric and magnetic fields on the induced SAR separately. From our computational results, the SARs obtained from our quasi-static method are found to be in good agreement with full-wave analysis for different positions of the cylindrical model relative to the wireless power transfer system, confirming the applicability of the quasi-static approximation in the 10 MHz band. The SAR induced by the external electric field is found to be marginal as compared to that induced by the magnetic field. Thus, the dosimetry for the external magnetic field, which may be marginally perturbed by the presence of biological tissue, is confirmed to be essential for SAR compliance in the 10 MHz band or lower. This confirmation also suggests that the current in the coil rather than the transferred power is essential for SAR compliance.

  18. Confirmation of quasi-static approximation in SAR evaluation for a wireless power transfer system

    International Nuclear Information System (INIS)

    Hirata, Akimasa; Ito, Fumihiro; Laakso, Ilkka

    2013-01-01

    The present study discusses the applicability of the magneto-quasi-static approximation to the calculation of the specific absorption rate (SAR) in a cylindrical model for a wireless power transfer system. Resonant coils with different parameters were considered in the 10 MHz band. A two-step quasi-static method that is comprised of the method of moments and the scalar-potential finite-difference methods is applied, which can consider the effects of electric and magnetic fields on the induced SAR separately. From our computational results, the SARs obtained from our quasi-static method are found to be in good agreement with full-wave analysis for different positions of the cylindrical model relative to the wireless power transfer system, confirming the applicability of the quasi-static approximation in the 10 MHz band. The SAR induced by the external electric field is found to be marginal as compared to that induced by the magnetic field. Thus, the dosimetry for the external magnetic field, which may be marginally perturbed by the presence of biological tissue, is confirmed to be essential for SAR compliance in the 10 MHz band or lower. This confirmation also suggests that the current in the coil rather than the transferred power is essential for SAR compliance. (note)

  19. 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...

  20. Tracking morphological changes and slope instability using spaceborne and ground-based SAR data

    Science.gov (United States)

    Di Traglia, Federico; Nolesini, Teresa; Ciampalini, Andrea; Solari, Lorenzo; Frodella, William; Bellotti, Fernando; Fumagalli, Alfio; De Rosa, Giuseppe; Casagli, Nicola

    2018-01-01

    Stromboli (Aeolian Archipelago, Italy) is an active volcano that is frequently affected by moderate to large mass wasting, which has occasionally triggered tsunamis. With the aim of understanding the relationship between the geomorphologic evolution and slope instability of Stromboli, remote sensing information from space-born Synthetic Aperture Radar (SAR) change detection and interferometry (InSAR) () and Ground Based InSAR (GBInSAR) was compared with field observations and morphological analyses. Ground reflectivity and SqueeSAR™ (an InSAR algorithm for surface deformation monitoring) displacement measurements from X-band COSMO-SkyMed satellites (CSK) were analysed together with displacement measurements from a permanent-sited, Ku-band GBInSAR system. Remote sensing results were compared with a preliminary morphological analysis of the Sciara del Fuoco (SdF) steep volcanic flank, which was carried out using a high-resolution Digital Elevation Model (DEM). Finally, field observations, supported by infrared thermographic surveys (IRT), allowed the interpretation and validation of remote sensing data. The analysis of the entire dataset (collected between January 2010 and December 2014) covers a period characterized by a low intensity of Strombolian activity. This period was punctuated by the occurrence of lava overflows, occurring from the crater terrace evolving downslope toward SdF, and flank eruptions, such as the 2014 event. The amplitude of the CSK images collected between February 22nd, 2010, and December 18th, 2014, highlights that during periods characterized by low-intensity Strombolian activity, the production of materials ejected from the crater terrace towards the SdF is generally low, and erosion is the prevailing process mainly affecting the central sector of the SdF. CSK-SqueeSAR™ and GBInSAR data allowed the identification of low displacements in the SdF, except for high displacement rates (up to 1.5 mm/h) that were measured following both lava

  1. Doppler Centroid Estimation for Airborne SAR Supported by POS and DEM

    Directory of Open Access Journals (Sweden)

    CHENG Chunquan

    2015-05-01

    Full Text Available It is difficult to estimate the Doppler frequency and modulating rate for airborne SAR by using traditional vector method due to instable flight and complex terrain. In this paper, it is qualitatively analyzed that the impacts of POS, DEM and their errors on airborne SAR Doppler parameters. Then an innovative vector method is presented based on the range-coplanarity equation to estimate the Doppler centroid taking the POS and DEM as auxiliary data. The effectiveness of the proposed method is validated and analyzed via the simulation experiments. The theoretical analysis and experimental results show that the method can be used to estimate the Doppler centroid with high accuracy even in the cases of high relief, instable flight, and large squint SAR.

  2. Work session on the SAR. Pt. 2

    International Nuclear Information System (INIS)

    Burkart, K.

    1980-01-01

    The present paper contains the tables of the contribution of K. Burkart 'Work Session on the SAR' to the IAEA Interregional Training Course held in Sept/Oct. 1980 at the Kernforschungszentrum Karlsruhe. (RW)

  3. Cleavage of spike protein of SARS coronavirus by protease factor Xa is associated with viral infectivity

    International Nuclear Information System (INIS)

    Du, Lanying; Kao, Richard Y.; Zhou, Yusen; He, Yuxian; Zhao, Guangyu; Wong, Charlotte; Jiang, Shibo; Yuen, Kwok-Yung; Jin, Dong-Yan; Zheng, Bo-Jian

    2007-01-01

    The spike (S) protein of SARS coronavirus (SARS-CoV) has been known to recognize and bind to host receptors, whose conformational changes then facilitate fusion between the viral envelope and host cell membrane, leading to viral entry into target cells. However, other functions of SARS-CoV S protein such as proteolytic cleavage and its implications to viral infection are incompletely understood. In this study, we demonstrated that the infection of SARS-CoV and a pseudovirus bearing the S protein of SARS-CoV was inhibited by a protease inhibitor Ben-HCl. Also, the protease Factor Xa, a target of Ben-HCl abundantly expressed in infected cells, was able to cleave the recombinant and pseudoviral S protein into S1 and S2 subunits, and the cleavage was inhibited by Ben-HCl. Furthermore, this cleavage correlated with the infectivity of the pseudovirus. Taken together, our study suggests a plausible mechanism by which SARS-CoV cleaves its S protein to facilitate viral infection

  4. Individual- and population-level toxicity of the insecticide, spirotetramat and the agricultural adjuvant, Destiny to the Cladoceran, Ceriodaphnia dubia.

    Science.gov (United States)

    Chen, Xue Dong; Stark, John D

    2010-08-01

    The effects of the tetramic acid insecticide, spirotetramat and the agricultural adjuvant, Destiny, were evaluated on the Cladoceran, Ceriodaphnia dubia. These compounds were evaluated separately and as a mixture because they can be applied together for control of certain crop pests and therefore have the potential to enter surface water as a binary mixture. Acute mortality estimates (48 h) were developed followed by chronic exposure (8 days) studies where several population parameters were recorded. Acute LC50 and 95% CL for spirotetramat and Destiny were estimated to be 23.8 (14.5-35.4) and 26.71 (20.8-34.0) mg/l, respectively. Thus, spirotetramat and Destiny were equitoxic to C. dubia at LC50. For the chronic population study, C. dubia populations were exposed to a range of concentrations for spirotetramat and Destiny singly and as a mixture. Each chemical alone reduced the number of founding individuals, offspring/female, final population size, and population growth rate in a concentration-dependent manner. However, exposure to the mixture caused significantly greater reductions in these parameters than either compound alone. These results indicate that agricultural adjuvants and pesticides may cause more damage to aquatic organisms as a mixture than either product alone. Therefore, future evaluations of pesticide effects should consider the effects of adjuvants as a mixture with pesticides when these products are recommended to be applied together for pest control.

  5. The behavioral impacts of SARS and its implication for societal preparedness for other emerging infections

    Directory of Open Access Journals (Sweden)

    Kathleen Pik-san Kwok

    2008-07-01

    Full Text Available Introduction: This study examined public attitudes toward Severe Acute Respiratory Syndrome (SARS in Hong Kong three months after the peak of the 2003 outbreak in order to shed light on SARS-related complaints received by the Equal Opportunities Commission of Hong Kong. Methods: A cross-sectional telephone survey was conducted three months after the SARS outbreak of 1,023 randomly selected Chinese-speaking residents in Hong Kong. Results: Most of the respondents (72.2% reported worry about contracting SARS. They attributed their anxiety to the perceived danger of the disease, the government’s unsatisfactory style of crisis management, and inconsistent health information dissemination. The majority of respondents endorsed up to 3 avoidant (67.8% and 3 imposing (72.7% attitudes toward individuals and/or situations considered to be at risk of spreading SARS. Logistic Regression analyses indicated that the odds for avoidant and imposing attitudes increased significantly for those who were middle aged (35-54, employed full-time or part-time, and worried over contracting SARS. Conclusions: Public attitudes that endorsed avoidant and imposing behaviors were common during the outbreak of SARS. While essential for preventive health practices, they might bring about workplace conflicts, stigma, and other negative interpersonal experiences. These problems may complicate public health efforts to control the epidemic. They may also suggest ways in which societal preparedness for future emerging infections can be improved.

  6. Multi-dimensional SAR tomography for monitoring the deformation of newly built concrete buildings

    Science.gov (United States)

    Ma, Peifeng; Lin, Hui; Lan, Hengxing; Chen, Fulong

    2015-08-01

    Deformation often occurs in buildings at early ages, and the constant inspection of deformation is of significant importance to discover possible cracking and avoid wall failure. This paper exploits the multi-dimensional SAR tomography technique to monitor the deformation performances of two newly built buildings (B1 and B2) with a special focus on the effects of concrete creep and shrinkage. To separate the nonlinear thermal expansion from total deformations, the extended 4-D SAR technique is exploited. The thermal map estimated from 44 TerraSAR-X images demonstrates that the derived thermal amplitude is highly related to the building height due to the upward accumulative effect of thermal expansion. The linear deformation velocity map reveals that B1 is subject to settlement during the construction period, in addition, the creep and shrinkage of B1 lead to wall shortening that is a height-dependent movement in the downward direction, and the asymmetrical creep of B2 triggers wall deflection that is a height-dependent movement in the deflection direction. It is also validated that the extended 4-D SAR can rectify the bias of estimated wall shortening and wall deflection by 4-D SAR.

  7. UTILIZING SAR AND MULTISPECTRAL INTEGRATED DATA FOR EMERGENCY RESPONSE

    Directory of Open Access Journals (Sweden)

    S. Havivi

    2016-06-01

    Full Text Available Satellite images are used widely in the risk cycle to understand the exposure, refine hazard maps and quickly provide an assessment after a natural or man-made disaster. Though there are different types of satellite images (e.g. optical, radar these have not been combined for risk assessments. The characteristics of different remote sensing data type may be extremely valuable for monitoring and evaluating the impacts of disaster events, to extract additional information thus making it available for emergency situations. To base this approach, two different change detection methods, for two different sensor's data were used: Coherence Change Detection (CCD for SAR data and Covariance Equalization (CE for multispectral imagery. The CCD provides an identification of the stability of an area, and shows where changes have occurred. CCD shows subtle changes with an accuracy of several millimetres to centimetres. The CE method overcomes the atmospheric effects differences between two multispectral images, taken at different times. Therefore, areas that had undergone a major change can be detected. To achieve our goals, we focused on the urban areas affected by the tsunami event in Sendai, Japan that occurred on March 11, 2011 which affected the surrounding area, coastline and inland. High resolution TerraSAR-X (TSX and Landsat 7 images, covering the research area, were acquired for the period before and after the event. All pre-processed and processed according to each sensor. Both results, of the optical and SAR algorithms, were combined by resampling the spatial resolution of the Multispectral data to the SAR resolution. This was applied by spatial linear interpolation. A score representing the damage level in both products was assigned. The results of both algorithms, high level of damage is shown in the areas closer to the sea and shoreline. Our approach, combining SAR and multispectral images, leads to more reliable information and provides a

  8. 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

  9. Bioinformatics analysis of SARS coronavirus genome polymorphism

    Directory of Open Access Journals (Sweden)

    Pavlović-Lažetić Gordana M

    2004-05-01

    Full Text Available Abstract Background We have compared 38 isolates of the SARS-CoV complete genome. The main goal was twofold: first, to analyze and compare nucleotide sequences and to identify positions of single nucleotide polymorphism (SNP, insertions and deletions, and second, to group them according to sequence similarity, eventually pointing to phylogeny of SARS-CoV isolates. The comparison is based on genome polymorphism such as insertions or deletions and the number and positions of SNPs. Results The nucleotide structure of all 38 isolates is presented. Based on insertions and deletions and dissimilarity due to SNPs, the dataset of all the isolates has been qualitatively classified into three groups each having their own subgroups. These are the A-group with "regular" isolates (no insertions / deletions except for 5' and 3' ends, the B-group of isolates with "long insertions", and the C-group of isolates with "many individual" insertions and deletions. The isolate with the smallest average number of SNPs, compared to other isolates, has been identified (TWH. The density distribution of SNPs, insertions and deletions for each group or subgroup, as well as cumulatively for all the isolates is also presented, along with the gene map for TWH. Since individual SNPs may have occurred at random, positions corresponding to multiple SNPs (occurring in two or more isolates are identified and presented. This result revises some previous results of a similar type. Amino acid changes caused by multiple SNPs are also identified (for the annotated sequences, as well as presupposed amino acid changes for non-annotated ones. Exact SNP positions for the isolates in each group or subgroup are presented. Finally, a phylogenetic tree for the SARS-CoV isolates has been produced using the CLUSTALW program, showing high compatibility with former qualitative classification. Conclusions The comparative study of SARS-CoV isolates provides essential information for genome

  10. 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

  11. Confined aquifer head measurements and storage properties in the San Luis Valley, Colorado, from spaceborne InSAR observations

    Science.gov (United States)

    Chen, Jingyi; Knight, Rosemary; Zebker, Howard A.; Schreüder, Willem A.

    2016-05-01

    Interferometric Synthetic Aperture Radar (InSAR), a remote sensing technique for measuring centimeter-level surface deformation, is used to estimate hydraulic head in the confined aquifer of the San Luis Valley (SLV), Colorado. Reconstructing head measurements from InSAR in agricultural regions can be difficult, as InSAR phase data are often decorrelated due to vegetation growth. Analysis of 17 L-band ALOS PALSAR scenes, acquired between January 2007 and March 2011, demonstrates that comprehensive InSAR deformation measurements can be recovered over the vegetated groundwater basin with an improved processing strategy. Local skeletal storage coefficients and time delays between the head change and deformation are estimated through a joint InSAR-well data analysis. InSAR subsidence estimates are transformed to head changes with finer temporal and spatial resolution than is possible using existing well records alone. Both InSAR and well data suggest that little long-term water-storage loss occurred in the SLV over the study period and that inelastic compaction was negligible. The seasonal head variations derived from InSAR are consistent with the existing well data at most locations where confined aquifer pumping activity dominates. Our results demonstrate the advantages of InSAR measurements for basin-wide characterization of aquifer storage properties and groundwater levels over agricultural regions.

  12. Monitoring of surface deformation in open pit mine using DInSAR time-series: a case study in the N5W iron mine (Carajás, Brazil) using TerraSAR-X data

    Science.gov (United States)

    Mura, José C.; Paradella, Waldir R.; Gama, Fabio F.; Santos, Athos R.; Galo, Mauricio; Camargo, Paulo O.; Silva, Arnaldo Q.; Silva, Guilherme G.

    2014-10-01

    We present an investigation of surface deformation using Differential SAR Interferometry (DInSAR) time-series carried out in an active open pit iron mine, the N5W, located in the Carajás Mineral Province (Brazilian Amazon region), using 33 TerraSAR-X (TSX-1) scenes. This mine has presented a historical of instability and surface monitoring measurements over sectors of the mine (pit walls) have been done based on ground based radar. Two complementary approaches were used: the standard DInSAR configuration, as an early warning of the slope instability conditions, and the DInSAR timeseries analysis. In order to decrease the topographic phase error a high resolution DEM was generated based on a stereo GeoEye-1 pair. Despite the fact that a DinSAR contains atmospheric and topographic phase artifacts and noise, it was possible to detect deformation in some interferometric pairs, covering pit benches, road ramps and waste piles. The timeseries analysis was performed using the 31 interferometric pairs, which were selected based on the highest mean coherence of a stack of 107 interferograms, presenting less phase unwrapping errors. The time-series deformation was retrieved by the Least-Squares (LS) solution using an extension of the Singular Value Decomposition (SVD), with a set of additional weighted constrain on the acceleration deformation. The atmospheric phase artifacts were filtered in the space-time domain and the DEM height errors were estimated based on the normal baseline diversity. The DInSAR time-series investigation showed good results for monitoring surface displacement in the N5W mine located in a tropical rainforest environment, providing very useful information about the ground movement for alarm, planning and risk assessment.

  13. 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.......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....

  14. The SARVIEWS Project: Automated SAR Processing in Support of Operational Near Real-time Volcano Monitoring

    Science.gov (United States)

    Meyer, F. J.; Webley, P. W.; Dehn, J.; Arko, S. A.; McAlpin, D. B.; Gong, W.

    2016-12-01

    Volcanic eruptions are among the most significant hazards to human society, capable of triggering natural disasters on regional to global scales. In the last decade, remote sensing has become established in operational volcano monitoring. Centers like the Alaska Volcano Observatory rely heavily on remote sensing data from optical and thermal sensors to provide time-critical hazard information. Despite this high use of remote sensing data, the presence of clouds and a dependence on solar illumination often limit their impact on decision making. Synthetic Aperture Radar (SAR) systems are widely considered superior to optical sensors in operational monitoring situations, due to their weather and illumination independence. Still, the contribution of SAR to operational volcano monitoring has been limited in the past due to high data costs, long processing times, and low temporal sampling rates of most SAR systems. In this study, we introduce the automatic SAR processing system SARVIEWS, whose advanced data analysis and data integration techniques allow, for the first time, a meaningful integration of SAR into operational monitoring systems. We will introduce the SARVIEWS database interface that allows for automatic, rapid, and seamless access to the data holdings of the Alaska Satellite Facility. We will also present a set of processing techniques designed to automatically generate a set of SAR-based hazard products (e.g. change detection maps, interferograms, geocoded images). The techniques take advantage of modern signal processing and radiometric normalization schemes, enabling the combination of data from different geometries. Finally, we will show how SAR-based hazard information is integrated in existing multi-sensor decision support tools to enable joint hazard analysis with data from optical and thermal sensors. We will showcase the SAR processing system using a set of recent natural disasters (both earthquakes and volcanic eruptions) to demonstrate its

  15. Remote Monitoring of Groundwater Overdraft Using GRACE and InSAR

    Science.gov (United States)

    Scher, C.; Saah, D.

    2017-12-01

    Gravity Recovery and Climate Experiment (GRACE) data paired with radar-derived analyses of volumetric changes in aquifer storage capacity present a viable technique for remote monitoring of aquifer depletion. Interferometric Synthetic Aperture Radar (InSAR) analyses of ground level subsidence can account for a significant portion of mass loss observed in GRACE data and provide information on point-sources of overdraft. This study summed one water-year of GRACE monthly mass change grids and delineated regions with negative water storage anomalies for further InSAR analyses. Magnitude of water-storage anomalies observed by GRACE were compared to InSAR-derived minimum volumetric changes in aquifer storage capacity as a result of measurable compaction at the surface. Four major aquifers were selected within regions where GRACE observed a net decrease in water storage (Central Valley, California; Mekong Delta, Vietnam; West Bank, occupied Palestinian Territory; and the Indus Basin, South Asia). Interferogram imagery of the extent and magnitude of subsidence within study regions provided estimates for net minimum volume of groundwater extracted between image acquisitions. These volumetric estimates were compared to GRACE mass change grids to resolve a percent contribution of mass change observed by GRACE likely due to groundwater overdraft. Interferograms revealed characteristic cones of depression within regions of net mass loss observed by GRACE, suggesting point-source locations of groundwater overdraft and demonstrating forensic potential for the use of InSAR and GRACE data in remote monitoring of aquifer depletion. Paired GRACE and InSAR analyses offer a technique to increase the spatial and temporal resolution of remote applications for monitoring groundwater overdraft in addition to providing a novel parameter - measurable vertical deformation at the surface - to global groundwater models.

  16. 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.

  17. Ocean Wave Parameters Retrieval from Sentinel-1 SAR Imagery

    Directory of Open Access Journals (Sweden)

    Weizeng Shao

    2016-08-01

    Full Text Available In this paper, a semi-empirical algorithm for significant wave height (Hs and mean wave period (Tmw retrieval from C-band VV-polarization Sentinel-1 synthetic aperture radar (SAR imagery is presented. We develop a semi-empirical function for Hs retrieval, which describes the relation between Hs and cutoff wavelength, radar incidence angle, and wave propagation direction relative to radar look direction. Additionally, Tmw can be also calculated through Hs and cutoff wavelength by using another empirical function. We collected 106 C-band stripmap mode Sentinel-1 SAR images in VV-polarization and wave measurements from in situ buoys. There are a total of 150 matchup points. We used 93 matchups to tune the coefficients of the semi-empirical algorithm and the rest 57 matchups for validation. The comparison shows a 0.69 m root mean square error (RMSE of Hs with a 18.6% of scatter index (SI and 1.98 s RMSE of Tmw with a 24.8% of SI. Results indicate that the algorithm is suitable for wave parameters retrieval from Sentinel-1 SAR data.

  18. Estimation of Boreal Forest Biomass Using Spaceborne SAR Systems

    Science.gov (United States)

    Saatchi, Sassan; Moghaddam, Mahta

    1995-01-01

    In this paper, we report on the use of a semiempirical algorithm derived from a two layer radar backscatter model for forest canopies. The model stratifies the forest canopy into crown and stem layers, separates the structural and biometric attributes of the canopy. The structural parameters are estimated by training the model with polarimetric SAR (synthetic aperture radar) data acquired over homogeneous stands with known above ground biomass. Given the structural parameters, the semi-empirical algorithm has four remaining parameters, crown biomass, stem biomass, surface soil moisture, and surface rms height that can be estimated by at least four independent SAR measurements. The algorithm has been used to generate biomass maps over the entire images acquired by JPL AIRSAR and SIR-C SAR systems. The semi-empirical algorithms are then modified to be used by single frequency radar systems such as ERS-1, JERS-1, and Radarsat. The accuracy. of biomass estimation from single channel radars is compared with the case when the channels are used together in synergism or in a polarimetric system.

  19. Mapping boreal forest biomass with imagery from polarimetric and semi-polarimetric SAR sensors / Mapeamento da biomassa fl orestal boreal com imagens dos sensores SAR polarimétricos e semi-polarimétricos

    Directory of Open Access Journals (Sweden)

    Yrjo Rauste

    2008-09-01

    Full Text Available Data from ALOS/Palsar and TerraSAR-X were used to estimate forest biomass in Boreal forest zone in Finland. In the study site in Heinavesi (forest biomass between 0 and 255 tons/ha, the HH-polarised componentof dual-polarised ALOS/Palsar produced biomass estimation accuracies (RMSE between 35 and 42 tons/ha. In the Kuortane site (biomass0…188 tons/ha the RMSE varied between 25 and 28 tons/ha. Since onlytwo winter-time scenes from TerraSAR-X were available, TerraSAR-X results were very preliminary. The phase of the HH-VV cross-coherenceproduced the highest biomass-correlations among the TerraSAR-X derived features. This produced a biomass estimation accuracy (RMSE of 49 tons/ha in the Heinavesi study site.

  20. Application of postured human model for SAR measurements

    Science.gov (United States)

    Vuchkovikj, M.; Munteanu, I.; Weiland, T.

    2013-07-01

    In the last two decades, the increasing number of electronic devices used in day-to-day life led to a growing interest in the study of the electromagnetic field interaction with biological tissues. The design of medical devices and wireless communication devices such as mobile phones benefits a lot from the bio-electromagnetic simulations in which digital human models are used. The digital human models currently available have an upright position which limits the research activities in realistic scenarios, where postured human bodies must be considered. For this reason, a software application called "BodyFlex for CST STUDIO SUITE" was developed. In its current version, this application can deform the voxel-based human model named HUGO (Dipp GmbH, 2010) to allow the generation of common postures that people use in normal life, ensuring the continuity of tissues and conserving the mass to an acceptable level. This paper describes the enhancement of the "BodyFlex" application, which is related to the movements of the forearm and the wrist of a digital human model. One of the electromagnetic applications in which the forearm and the wrist movement of a voxel based human model has a significant meaning is the measurement of the specific absorption rate (SAR) when a model is exposed to a radio frequency electromagnetic field produced by a mobile phone. Current SAR measurements of the exposure from mobile phones are performed with the SAM (Specific Anthropomorphic Mannequin) phantom which is filled with a dispersive but homogeneous material. We are interested what happens with the SAR values if a realistic inhomogeneous human model is used. To this aim, two human models, a homogeneous and an inhomogeneous one, in two simulation scenarios are used, in order to examine and observe the differences in the results for the SAR values.

  1. Dynamic observation on changes of serum cytokines levels during convalescence in patients with SARS

    International Nuclear Information System (INIS)

    Zhang Jinshan; Chen Anwei; Li Min; Deng Yongmei; Du Ximing; Huang Guimin

    2004-01-01

    Objective: To explore the Th1/Th2 immuno-response advantage and dynamic changes of the corresponding serum cytokines levels during convalescence in patients with SARS. Methods: Serum cytokines (TNF, IL-1β, IL-2, IL-4, IL-6 , IL-8 and IL-10) levels were determined with RIA in 1) Group A, SARS patients in early recovery phase, n=23 2) Group B, subjects with history of close contact with SARS patients--possibly latently infected, n=37 3) Group C, SARS patients in late-recovery phase, n=21) and 4) Group D, controls, n=26). Results: 1) In Group A, the serum IL-1β levels were significantly lower than those in controls (P 0.05). 2) In Group B subjects, serum TNF, IL-6, IL-10 levels significantly higher (P 0.05). 4)Cytokines levels in Group C subjects differed little from those in controls (P>0.05). Conclusion: The Th1/Th2 corresponding serum cytokines levels approached normal in SARS patients by the late recovery phase, changes during the whole course of disease require further study. (authors)

  2. InSAR Deformation Time Series Processed On-Demand in the Cloud

    Science.gov (United States)

    Horn, W. B.; Weeden, R.; Dimarchi, H.; Arko, S. A.; Hogenson, K.

    2017-12-01

    During this past year, ASF has developed a cloud-based on-demand processing system known as HyP3 (http://hyp3.asf.alaska.edu/), the Hybrid Pluggable Processing Pipeline, for Synthetic Aperture Radar (SAR) data. The system makes it easy for a user who doesn't have the time or inclination to install and use complex SAR processing software to leverage SAR data in their research or operations. One such processing algorithm is generation of a deformation time series product, which is a series of images representing ground displacements over time, which can be computed using a time series of interferometric SAR (InSAR) products. The set of software tools necessary to generate this useful product are difficult to install, configure, and use. Moreover, for a long time series with many images, the processing of just the interferograms can take days. Principally built by three undergraduate students at the ASF DAAC, the deformation time series processing relies the new Amazon Batch service, which enables processing of jobs with complex interconnected dependencies in a straightforward and efficient manner. In the case of generating a deformation time series product from a stack of single-look complex SAR images, the system uses Batch to serialize the up-front processing, interferogram generation, optional tropospheric correction, and deformation time series generation. The most time consuming portion is the interferogram generation, because even for a fairly small stack of images many interferograms need to be processed. By using AWS Batch, the interferograms are all generated in parallel; the entire process completes in hours rather than days. Additionally, the individual interferograms are saved in Amazon's cloud storage, so that when new data is acquired in the stack, an updated time series product can be generated with minimal addiitonal processing. This presentation will focus on the development techniques and enabling technologies that were used in developing the time

  3. Seasonal and multi-year surface displacements measured by DInSAR in a High Arctic permafrost environment

    Science.gov (United States)

    Rudy, Ashley C. A.; Lamoureux, Scott F.; Treitz, Paul; Short, Naomi; Brisco, Brian

    2018-02-01

    Arctic landscapes undergo seasonal and long-term changes as the active layer thaws and freezes, which can result in localized or irregular subsidence leading to the formation of thermokarst terrain. Differential Interferometric Synthetic Aperture Radar (DInSAR) is a technique capable of measuring ground surface displacements resulting from thawing permafrost at centimetre precision and is quickly gaining acceptance as a means of measuring ground displacement in permafrost regions. Using RADARSAT-2 stacked DInSAR data from 2013 and 2015 we determined the magnitude and patterns of land surface change in a continuous permafrost environment. At our study site situated in the Canadian High Arctic, DInSAR seasonal ground displacement patterns were consistent with field observations of permafrost degradation. As expected, many DInSAR values are close to the detection threshold (i.e., 1 cm) and therefore do not indicate significant change; however, DInSAR seasonal ground displacement patterns aligned well with climatological and soil conditions and offer geomorphological insight into subsurface processes in permafrost environments. While our dataset is limited to two years of data representing a three-year time period, the displacements derived from DInSAR provide insight into permafrost change in a High Arctic environment and demonstrate that DInSAR is an applicable tool for understanding environmental change in remote permafrost regions.

  4. Semi-empirical modelling for forest above ground biomass estimation using hybrid and fully PolSAR data

    Science.gov (United States)

    Tomar, Kiledar S.; Kumar, Shashi; Tolpekin, Valentyn A.; Joshi, Sushil K.

    2016-05-01

    Forests act as sink of carbon and as a result maintains carbon cycle in atmosphere. Deforestation leads to imbalance in global carbon cycle and changes in climate. Hence estimation of forest biophysical parameter like biomass becomes a necessity. PolSAR has the ability to discriminate the share of scattering element like surface, double bounce and volume scattering in a single SAR resolution cell. Studies have shown that volume scattering is a significant parameter for forest biophysical characterization which mainly occurred from vegetation due to randomly oriented structures. This random orientation of forest structure causes shift in orientation angle of polarization ellipse which ultimately disturbs the radar signature and shows overestimation of volume scattering and underestimation of double bounce scattering after decomposition of fully PolSAR data. Hybrid polarimetry has the advantage of zero POA shift due to rotational symmetry followed by the circular transmission of electromagnetic waves. The prime objective of this study was to extract the potential of Hybrid PolSAR and fully PolSAR data for AGB estimation using Extended Water Cloud model. Validation was performed using field biomass. The study site chosen was Barkot Forest, Uttarakhand, India. To obtain the decomposition components, m-alpha and Yamaguchi decomposition modelling for Hybrid and fully PolSAR data were implied respectively. The RGB composite image for both the decomposition techniques has generated. The contribution of all scattering from each plot for m-alpha and Yamaguchi decomposition modelling were extracted. The R2 value for modelled AGB and field biomass from Hybrid PolSAR and fully PolSAR data were found 0.5127 and 0.4625 respectively. The RMSE for Hybrid and fully PolSAR between modelled AGB and field biomass were 63.156 (t ha-1) and 73.424 (t ha-1) respectively. On the basis of RMSE and R2 value, this study suggests Hybrid PolSAR decomposition modelling to retrieve scattering

  5. Mechanisms of the electron density depletion in the SAR arc region

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    Full Text Available This study compares the measurements of electron density and temperature and the integral airglow intensity at 630 nm in the SAR arc region and slightly south of this (obtained by the Isis 2 spacecraft during the 18 December 1971 magnetic storm, with the model results obtained using the time dependent one-dimensional mathematical model of the Earth's ionosphere and plasmasphere. The explicit expression in the third Enskog approximation for the electron thermal conductivity coefficient in the multicomponent mixture of ionized gases and a simplified calculation method for this coefficient presents an opportunity to calculate more exactly the electron temperature and density and 630 nm emission within SAR arc region are used in the model. Collisions between N2 and hot thermal electrons in the SAR arc region produce vibrationally excited nitrogen molecules. It appears that the loss rate of O+(4S due to reactions with the vibrationally excited nitrogen is enough to explain electron density depression by a factor of two at F-region heights and the topside ionosphere density variations within the SAR arc if the erosion of plasma within geomagnetic field tubes, during the main phase of the geomagnetic storm and subsequent filling of geomagnetic tubes during the recovery phase, are considered. To explain the disagreement by a factor 1.5 between the observed and modeled SAR arc electron densities an additional plasma drift velocity ~–30 m s–1 in the ion continuity equations is needed during the recovery phase. This additional plasma drift velocity is likely caused by the transition from convecting to corotating flux tubes on the equatorward wall of the trough. The electron densities and temperatures and 630 nm integral intensity at the SAR arc and slightly south of this region as measured for the 18 December 1971 magnetic storm were correctly described by the model without perpendicular electric fields

  6. Toward regional corrections of long period CMT inversions using InSAR

    Science.gov (United States)

    Shakibay Senobari, N.; Funning, G.; Ferreira, A. M.

    2017-12-01

    One of InSAR's main strengths, with respect to other methods of studying earthquakes, is finding the accurate location of the best point source (or `centroid') for an earthquake. While InSAR data have great advantages for study of shallow earthquakes, the number of earthquakes for which we have InSAR data is low, compared with the number of earthquakes recorded seismically. And though improvements to SAR satellite constellations have enhanced the use of InSAR data during earthquake response, post-event data still have a latency on the order of days. On the other hand, earthquake centroid inversion methods using long period seismic data (e.g. the Global CMT method) are fast but include errors caused by inaccuracies in both the Earth velocity model and in wave propagation assumptions (e.g. Hjörleifsdóttir and Ekström, 2010; Ferreira and Woodhouse, 2006). Here we demonstrate a method that combines the strengths of both methods, calculating regional travel-time corrections for long-period waveforms using accurate centroid locations from InSAR, then applying these to other events that occur in the same region. Our method is based on the observation that synthetic seismograms produced from InSAR source models and locations match the data very well except for some phase shifts (travel time biases) between the two waveforms, likely corresponding to inaccuracies in Earth velocity models (Weston et al., 2014). Our previous work shows that adding such phase shifts to the Green's functions can improve the accuracy of long period seismic CMT inversions by reducing tradeoffs between the moment tensor components and centroid location (e.g. Shakibay Senobari et al., AGU Fall Meeting 2015). Preliminary work on several pairs of neighboring events (e.g. Landers-Hector Mine, the 2000 South Iceland earthquake sequences) shows consistent azimuthal patterns of these phase shifts for nearby events at common stations. These phase shift patterns strongly suggest that it is possible to

  7. A study on SARS awareness and health-seeking behaviour - findings from a sampled population attending National Healthcare Group Polyclinics.

    Science.gov (United States)

    Seng, S L; Lim, P S; Ng, M Y; Wong, H B; Emmanuel, S C

    2004-09-01

    The study aimed to assess the effectiveness of massive SARS public education effort on SARS awareness and the conduct of those suspected of having SARS. Five hundred and ninety-three respondents attending the National Healthcare Group Polyclinics (NHGP) participated in the survey from 9 to 13 June 2003. Associations between awareness of SARS symptoms and (i) first action to be taken and (ii) mode of transportation used, if the respondent was suspected of having SARS, were analysed using Chi-square or Fisher's exact tests. Logistic regression was performed to adjust for relevant covariates. The majority (92.7%) of the respondents were aware of SARS symptoms. Television (91.6%), newspaper (65.2%) and radio (30.4%) formed the top 3 sources of information on SARS. Slightly more than half (51.6%) of those who suspect themselves of having SARS would choose to visit their primary health care doctors, while 22.7% of the respondents would go to Tan Tock Seng Hospital (TTSH). If they suspected themselves to have SARS, most (84.9%) of the 578 respondents would react appropriately by taking the SARS ambulance or driving themselves to TTSH. However, 60 respondents would nonetheless take public transport to TTSH [by taxi 8.5%, mass rapid transit (MRT) or bus 1.9%]. In particular, the retired with lower educational levels were likely to be oblivious both to the symptoms of SARS and the possible consequences of travelling by inappropriate transport. Despite more than 2 months of intensive SARS public education in Singapore, there remain important gaps in knowledge and appropriate behaviour that have to be bridged.

  8. SAR-Based Wind Resource Statistics in the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Alfredo Peña

    2011-01-01

    Full Text Available Ocean winds in the Baltic Sea are expected to power many wind farms in the coming years. This study examines satellite Synthetic Aperture Radar (SAR images from Envisat ASAR for mapping wind resources with high spatial resolution. Around 900 collocated pairs of wind speed from SAR wind maps and from 10 meteorological masts, established specifically for wind energy in the study area, are compared. The statistical results comparing in situ wind speed and SAR-based wind speed show a root mean square error of 1.17 m s−1, bias of −0.25 m s−1, standard deviation of 1.88 m s−1 and correlation coefficient of R2 0.783. Wind directions from a global atmospheric model, interpolated in time and space, are used as input to the geophysical model function CMOD-5 for SAR wind retrieval. Wind directions compared to mast observations show a root mean square error of 6.29° with a bias of 7.75°, standard deviation of 20.11° and R2 of 0.950. The scale and shape parameters, A and k, respectively, from the Weibull probability density function are compared at only one available mast and the results deviate ~2% for A but ~16% for k. Maps of A and k, and wind power density based on more than 1000 satellite images show wind power density values to range from 300 to 800 W m−2 for the 14 existing and 42 planned wind farms.

  9. SarA is a negative regulator of Staphylococcus epidermidis biofilm formation

    DEFF Research Database (Denmark)

    Martin, Christer; Heinze, C.; Busch, M.

    2012-01-01

    Biofilm formation is essential for Staphylococcus epidermidis pathogenicity in implant-associated infections. Nonetheless, large proportions of invasive S. epidermidis isolates fail to show accumulative biofilm growth in vitro. We here tested the hypothesis that this apparent paradox is related...... virulence. Genetic analysis revealed that inactivation of sarA induced biofilm formation via over-expression of the giant 1 MDa extracellular matrix binding protein (Embp), serving as an intercellular adhesin. In addition to Embp, increased extracellular DNA (eDNA) release significantly contributed...... to biofilm formation in mutant 1585ΔsarA. Increased eDNA amounts indirectly resulted from up-regulation of metalloprotease SepA, leading to boosted processing of major autolysin AtlE, in turn inducing augmented autolysis and release of chromosomal DNA. Hence, this study identifies sarA as a negative...

  10. SAR in the mother and foetus for RF plane wave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Dimbylow, Peter [Health Protection Agency, Radiation Protection Division, Chilton, Didcot, Oxon OX11 0RQ (United Kingdom)

    2007-07-07

    This paper describes the finite-difference time-domain calculation of SAR from 20 MHz to 3 GHz in hybrid voxel-mathematical models of the pregnant female. Mathematical models of the developing foetus at 8-, 13-, 26- and 38-week gestation were converted into voxels and combined with the reference adult female model, NAOMI at a resolution of 2 mm. Whole-body averaged SAR in the mother is presented as well as the average over the foetus, over the foetal brain and in 10 g of the foetus. The electric field values required to produce the ICNIRP public exposure restriction of 2 W kg{sup -1} when averaged over 10 g of the foetus were calculated. Comparison suggests that the ICNIRP public reference level is a conservative predictor of local SAR in the foetus.

  11. SAR in the mother and foetus for RF plane wave irradiation

    International Nuclear Information System (INIS)

    Dimbylow, Peter

    2007-01-01

    This paper describes the finite-difference time-domain calculation of SAR from 20 MHz to 3 GHz in hybrid voxel-mathematical models of the pregnant female. Mathematical models of the developing foetus at 8-, 13-, 26- and 38-week gestation were converted into voxels and combined with the reference adult female model, NAOMI at a resolution of 2 mm. Whole-body averaged SAR in the mother is presented as well as the average over the foetus, over the foetal brain and in 10 g of the foetus. The electric field values required to produce the ICNIRP public exposure restriction of 2 W kg -1 when averaged over 10 g of the foetus were calculated. Comparison suggests that the ICNIRP public reference level is a conservative predictor of local SAR in the foetus

  12. Accuracy of clinical diagnosis versus the World Health Organization case definition in the Amoy Garden SARS cohort.

    Science.gov (United States)

    Wong, W N; Sek, Antonio C H; Lau, Rick F L; Li, K M; Leung, Joe K S; Tse, M L; Ng, Andy H W; Stenstrom, Robert

    2003-11-01

    To compare the diagnostic accuracy of emergency department (ED) physicians with the World Health Organization (WHO) case definition in a large community-based SARS (severe acute respiratory syndrome) cohort. This was a cohort study of all patients from Hong Kong's Amoy Garden complex who presented to an ED SARS screening clinic during a 2-month outbreak. Clinical findings and WHO case definition criteria were recorded, along with ED diagnoses. Final diagnoses were established independently based on relevant diagnostic tests performed after the ED visit. Emergency physician diagnostic accuracy was compared with that of the WHO SARS case definition. Sensitivity, specificity, predictive values and likelihood ratios were calculated using standard formulae. During the study period, 818 patients presented with SARS-like symptoms, including 205 confirmed SARS, 35 undetermined SARS and 578 non-SARS. Sensitivity, specificity and accuracy were 91%, 96% and 94% for ED clinical diagnosis, versus 42%, 86% and 75% for the WHO case definition. Positive likelihood ratios (LR+) were 21.1 for physician judgement and 3.1 for the WHO criteria. Negative likelihood ratios (LR-) were 0.10 for physician judgement and 0.67 for the WHO criteria, indicating that clinician judgement was a much more powerful predictor than the WHO criteria. Physician clinical judgement was more accurate than the WHO case definition. Reliance on the WHO case definition as a SARS screening tool may lead to an unacceptable rate of misdiagnosis. The SARS case definition must be revised if it is to be used as a screening tool in emergency departments and primary care settings.

  13. Inhibition of cytokine gene expression and induction of chemokine genes in non-lymphatic cells infected with SARS coronavirus

    Directory of Open Access Journals (Sweden)

    Weber Friedemann

    2006-03-01

    Full Text Available Abstract Background SARS coronavirus (SARS-CoV is the etiologic agent of the severe acute respiratory syndrome. SARS-CoV mainly infects tissues of non-lymphatic origin, and the cytokine profile of those cells can determine the course of disease. Here, we investigated the cytokine response of two human non-lymphatic cell lines, Caco-2 and HEK 293, which are fully permissive for SARS-CoV. Results A comparison with established cytokine-inducing viruses revealed that SARS-CoV only weakly triggered a cytokine response. In particular, SARS-CoV did not activate significant transcription of the interferons IFN-α, IFN-β, IFN-λ1, IFN-λ2/3, as well as of the interferon-induced antiviral genes ISG56 and MxA, the chemokine RANTES and the interleukine IL-6. Interestingly, however, SARS-CoV strongly induced the chemokines IP-10 and IL-8 in the colon carcinoma cell line Caco-2, but not in the embryonic kidney cell line 293. Conclusion Our data indicate that SARS-CoV suppresses the antiviral cytokine system of non-immune cells to a large extent, thus buying time for dissemination in the host. However, synthesis of IP-10 and IL-8, which are established markers for acute-stage SARS, escapes the virus-induced silencing at least in some cell types. Therefore, the progressive infiltration of immune cells into the infected lungs observed in SARS patients could be due to the production of these chemokines by the infected tissue cells.

  14. C-band solid state dual polarization T/R modules for airborne SAR systems

    NARCIS (Netherlands)

    Vermeulen, B.C.B.; Koomen, P.J.; Hoogeboom, P.; Snoeij, P.; Pouwels, H.

    1996-01-01

    The use of distributed power in a, on a phased array antenna based, SAR system offers new possibilities for the system operation. As a preparation for future spaceborne SAR systems using solid state transmitters with electronically steerable phased array antenna, the PHARUS system has been

  15. Combining TerraSAR-X and Landsat Images for Emergency Response in Urban Environments

    Directory of Open Access Journals (Sweden)

    Shiran Havivi

    2018-05-01

    Full Text Available Rapid damage mapping following a disaster event, especially in an urban environment, is critical to ensure that the emergency response in the affected area is rapid and efficient. This work presents a new method for mapping damage assessment in urban environments. Based on combining SAR and optical data, the method is applicable as support during initial emergency planning and rescue operations. The study focuses on the urban areas affected by the Tohoku earthquake and subsequent tsunami event in Japan that occurred on 11 March 2011. High-resolution TerraSAR-X (TSX images of before and after the event, and a Landsat 5 image before the event were acquired. The affected areas were analyzed with the SAR data using only one interferometric SAR (InSAR coherence map. To increase the damage mapping accuracy, the normalized difference vegetation index (NDVI was applied. The generated map, with a grid size of 50 m, provides a quantitative assessment of the nature and distribution of the damage. The damage mapping shows detailed information about the affected area, with high overall accuracy (89%, and high Kappa coefficient (82% and, as expected, it shows total destruction along the coastline compared to the inland region.

  16. Assessment of Polarimetric SAR Interferometry for Improving Ship Classification based on Simulated Data

    Directory of Open Access Journals (Sweden)

    Jordi J. Mallorqui

    2008-12-01

    Full Text Available This paper uses a complete and realistic SAR simulation processing chain, GRECOSAR, to study the potentialities of Polarimetric SAR Interferometry (POLInSAR in the development of new classification methods for ships. Its high processing efficiency and scenario flexibility have allowed to develop exhaustive scattering studies. The results have revealed, first, vessels’ geometries can be described by specific combinations of Permanent Polarimetric Scatterers (PePS and, second, each type of vessel could be characterized by a particular spatial and polarimetric distribution of PePS. Such properties have been recently exploited to propose a new Vessel Classification Algorithm (VCA working with POLInSAR data, which, according to several simulation tests, may provide promising performance in real scenarios. Along the paper, explanation of the main steps summarizing the whole research activity carried out with ships and GRECOSAR are provided as well as examples of the main results and VCA validation tests. Special attention will be devoted to the new improvements achieved, which are related to simulations processing a new and highly realistic sea surface model. The paper will show that, for POLInSAR data with fine resolution, VCA can help to classify ships with notable robustness under diverse and adverse observation conditions.

  17. Implementation of integrated circuit and design of SAR ADC for fully implantable hearing aids.

    Science.gov (United States)

    Kim, Jong Hoon; Lee, Jyung Hyun; Cho, Jin-Ho

    2017-07-20

    The hearing impaired population has been increasing; many people suffer from hearing problems. To deal with this difficulty, various types of hearing aids are being rapidly developed. In particular, fully implantable hearing aids are being actively studied to improve the performance of existing hearing aids and to reduce the stigma of hearing loss patients. It has to be of small size and low-power consumption for easy implantation and long-term use. The objective of the study was to implement a small size and low-power consumption successive approximation register analog-to-digital converter (SAR ADC) for fully implantable hearing aids. The ADC was selected as the SAR ADC because its analog circuit components are less required by the feedback circuit of the SAR ADC than the sigma-delta ADC which is conventionally used in hearing aids, and it has advantages in the area and power consumption. So, the circuit of SAR ADC is designed considering the speech region of humans because the objective is to deliver the speech signals of humans to hearing loss patients. If the switch of sample and hold works in the on/off positions, the charge injection and clock feedthrough are produced by a parasitic capacitor. These problems affect the linearity of the hold voltage, and as a result, an error of the bit conversion is generated. In order to solve the problem, a CMOS switch that consists of NMOS and PMOS was used, and it reduces the charge injection because the charge carriers in the NMOS and PMOS have inversed polarity. So, 16 bit conversion is performed before the occurrence of the Least Significant Bit (LSB) error. In order to minimize the offset voltage and power consumption of the designed comparator, we designed a preamplifier with current mirror. Therefore, the power consumption was reduced by the power control switch used in the comparator. The layout of the designed SAR ADC was performed by Virtuoso Layout Editor (Cadence, USA). In the layout result, the size of the

  18. 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...

  19. 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...

  20. Estimating the Doppler centroid of SAR data

    DEFF Research Database (Denmark)

    Madsen, Søren Nørvang

    1989-01-01

    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......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...... 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...

  1. Validation of satellite SAR offshore wind speed maps to in-situ data, microscale and mesoscale model results

    DEFF Research Database (Denmark)

    Hasager, C.B.; Astrup, Poul; Barthelmie, R.J.

    2002-01-01

    the assumption of no error in the SAR wind speed maps and for an uncertainty of ± 10% at a confidence level of 90%. Around 100 satellite SAR scenes may be available for some sites on Earth but far few at other sites. Currently the numberof available satellite SAR scenes is increasing rapidly with ERS-2, RADARSAT......A validation study has been performed in order to investigate the precision and accuracy of the satellite-derived ERS-2 SAR wind products in offshore regions. The overall project goal is to develop a method for utilizing the satellite wind speed maps foroffshore wind resources, e.g. in future...... band in which the SAR wind speed observations have a strong negative bias. The bathymetry of Horns Rev combined with tidal currents give rise to bias in the SAR wind speed maps near areas of shallow, complex bottom topography in some cases. Atotal of 16 cases were analyzed for Horns Rev. For Maddalena...

  2. Development and Evaluation of Science and Technology Education Program Using Interferometric SAR

    Science.gov (United States)

    Ito, Y.; Ikemitsu, H.; Nango, K.

    2016-06-01

    This paper proposes a science and technology education program to teach junior high school students to measure terrain changes by using interferometric synthetic aperture radar (SAR). The objectives of the proposed program are to evaluate and use information technology by performing SAR data processing in order to measure ground deformation, and to incorporate an understanding of Earth sciences by analyzing interferometric SAR processing results. To draft the teaching guidance plan for the developed education program, this study considers both science and technology education. The education program was used in a Japanese junior high school. An educational SAR processor developed by the authors and the customized Delft object-oriented radar interferometric software package were employed. Earthquakes as diastrophism events were chosen as practical teaching materials. The selected events indicate clear ground deformation in differential interferograms with high coherence levels. The learners were able to investigate the ground deformations and disasters caused by the events. They interactively used computers and became skilled at recognizing the knowledge and techniques of information technology, and then they evaluated the technology. Based on the results of pre- and post-questionnaire surveys and self-evaluation by the learners, it was clarified that the proposed program was applicable for junior high school education, and the learners recognized the usefulness of Earth observation technology by using interferometric SAR. The usefulness of the teaching materials in the learning activities was also shown through the practical teaching experience.

  3. A very bright SAR arc: implications for extreme magnetosphere-ionosphere coupling

    Directory of Open Access Journals (Sweden)

    J. Baumgardner

    2007-01-01

    Full Text Available In contrast to the polar aurora visible during geomagnetic storms, stable auroral red (SAR arcs offer a sub-visual manifestation of direct magnetosphere-ionosphere (M-I coupling at midlatitudes. The SAR arc emission at 6300 Å is driven by field-aligned magnetospheric energy transport from ring current/plasmapause locations into the ionosphere-thermosphere system. The first SAR arc was observed at the dawn of the space age (1956, and the typical brightness levels and occurrence patterns obtained from subsequent decades of observations appear to be consistent with the downward heat conduction theory, i.e., heated ambient F-layer electrons excite oxygen atoms to produce a spectrally pure emission. On very rare occasions, a SAR arc has been reported to be at brightness levels visible to the naked eye. Here we report on the first case of a very bright SAR arc (~13 kilo-Rayleighs observed by four diagnostic systems that sampled various aspects of the sub-auroral domain near Millstone Hill, MA, on the night of 29 October 1991: an imaging spectrograph, an all-sky camera, an incoherent scatter radar (ISR, and a DMSP satellite. Simulations of emission using the ISR and DMSP data with the MSIS neutral atmosphere succeed in reproducing the brightness levels observed. This provides a robust confirmation of M-I coupling theory in its most extreme aeronomic form within the innermost magnetosphere (L~2 during a rare superstorm event. The unusually high brightness value appears to be due to the rare occurrence of the heating of dense ionospheric plasma just equatorward of the trough/plasmapause location, in contrast to the more typical heating of the less dense F-layer within the trough.

  4. Residents Look Forward to New Lease on Life Post SARS

    Institute of Scientific and Technical Information of China (English)

    JessyZhang

    2003-01-01

    A new craze has taken over Beijing: people of all ages can be found playing badminton on the sidewalks, in parks and virtually any open space theycan find. Thanks to SARS, taking up outdoor sports seems to be a hobby that is high on everyone's agenda. This is of course, just one small positive impact of SARS. After weathering the disaster, a few silver linings are emerging in the country's social life, economy and even administrative governance as the Eastern giant struggles to get on its feet.

  5. Dynamic Deformation of ETNA Volcano Observed by GPS and SAR Interferometry

    Science.gov (United States)

    Lundgren, P.; Rosen, P.; Webb, F.; Tesauro, M.; Lanari, R.; Sansosi, E.; Puglisi, G.; Bonforte, A.; Coltelli, M.

    1999-01-01

    Synthetic aperture radar (SAR) interferometry and GPS have shown that during the quiescent period from 1993-1995 Mt. Etna volcano, Italy, inflated. Since the initiation of eruptive activity since late 1995 the deformation has been more contentious. We will explore the detailed deformation during the period from 1995-1996 spanning the late stages of inflation and the beginning of eruptive activity. We use SAR interferometry and GPS data to measure the volcano deformation. We invert the observed deformation for both simple point source. le crack elastic sources or if warranted for a spheroidal pressure So In particular, we will examine the evolution of the inflation and the transition to a lesser deflation observed at the end of 1995. We use ERS-1/2 SAR data from both ascending and descending passes to allow for dense temporal 'sampling of the deformation and to allow us to critically assess atmospheric noise. Preliminary results from interferometry suggest that the inflation rate accelerated prior to resumption of activity in 1995, while GPS data suggest a more steady inflation with some fluctuation following the start of activity. This study will compare and contrast the interferometric SAR and GPS results and will address the strengths and weaknesses of each technique towards volcano deformation studies.

  6. OPERATIONAL SAR DATA PROCESSING IN GIS ENVIRONMENTS FOR RAPID DISASTER MAPPING

    Directory of Open Access Journals (Sweden)

    A. Meroni

    2013-05-01

    Full Text Available Having access to SAR data can be highly important and critical especially for disaster mapping. 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. Therefore, we present in this paper the operational processing of SAR data within a GIS environment for rapid disaster mapping. This is exemplified by the November 2010 flash flood in the Veneto region, Italy. A series of COSMO-SkyMed acquisitions was processed in ArcGIS® using a single-sensor, multi-mode, multi-temporal approach. The relevant processing steps were combined using the ArcGIS ModelBuilder to create a new model for rapid disaster mapping in ArcGIS, which can be accessed both via a desktop and a server environment.

  7. Natural phenomena risk analysis - an approach for the tritium facilities 5480.23 SAR natural phenomena hazards accident analysis

    International Nuclear Information System (INIS)

    Cappucci, A.J. Jr.; Joshi, J.R.; Long, T.A.; Taylor, R.P.

    1997-01-01

    A Tritium Facilities (TF) Safety Analysis Report (SAR) has been developed which is compliant with DOE Order 5480.23. The 5480.23 SAR upgrades and integrates the safety documentation for the TF into a single SAR for all of the tritium processing buildings. As part of the TF SAR effort, natural phenomena hazards (NPH) were analyzed. A cost effective strategy was developed using a team approach to take advantage of limited resources and budgets. During development of the Hazard and Accident Analysis for the 5480.23 SAR, a strategy was required to allow maximum use of existing analysis and to develop a cost effective graded approach for any new analysis in identifying and analyzing the bounding accidents for the TF. This approach was used to effectively identify and analyze NPH for the TF. The first part of the strategy consisted of evaluating the current SAR for the RTF to determine what NPH analysis could be used in the new combined 5480.23 SAR. The second part was to develop a method for identifying and analyzing NPH events for the older facilities which took advantage of engineering judgment, was cost effective, and followed a graded approach. The second part was especially challenging because of the lack of documented existing analysis considered adequate for the 5480.23 SAR and a limited budget for SAR development and preparation. This paper addresses the strategy for the older facilities

  8. Resilience of SAR11 bacteria to rapid acidification in the high-latitude open ocean.

    Science.gov (United States)

    Hartmann, Manuela; Hill, Polly G; Tynan, Eithne; Achterberg, Eric P; Leakey, Raymond J G; Zubkov, Mikhail V

    2016-02-01

    Ubiquitous SAR11 Alphaproteobacteria numerically dominate marine planktonic communities. Because they are excruciatingly difficult to cultivate, there is comparatively little known about their physiology and metabolic responses to long- and short-term environmental changes. As surface oceans take up anthropogenic, atmospheric CO2, the consequential process of ocean acidification could affect the global biogeochemical significance of SAR11. Shipping accidents or inadvertent release of chemicals from industrial plants can have strong short-term local effects on oceanic SAR11. This study investigated the effect of 2.5-fold acidification of seawater on the metabolism of SAR11 and other heterotrophic bacterioplankton along a natural temperature gradient crossing the North Atlantic Ocean, Norwegian and Greenland Seas. Uptake rates of the amino acid leucine by SAR11 cells as well as other bacterioplankton remained similar to controls despite an instant ∼50% increase in leucine bioavailability upon acidification. This high physiological resilience to acidification even without acclimation, suggests that open ocean dominant bacterioplankton are able to cope even with sudden and therefore more likely with long-term acidification effects. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. InSAR atmospheric correction using Himawari-8 Geostationary Meteorological Satellite

    Science.gov (United States)

    Kinoshita, Y.; Nimura, T.; Furuta, R.

    2017-12-01

    The atmospheric delay effect is one of the limitations for the accurate surface displacement detection by Synthetic Aperture Radar Interferometry (InSAR). Many previous studies have attempted to mitigate the neutral atmospheric delay in InSAR (e.g. Jolivet et al. 2014; Foster et al. 2006; Kinoshita et al. 2013). Hanssen et al. (2001) investigated the relationship between the 27 hourly observations of GNSS precipitable water vapor (PWV) and the infrared brightness temperature derived from visible satellite imagery, and showed a good correlation. Here we showed a preliminary result of the newly developed method for the neutral atmospheric delay correction using the Himawari-8 Japanese geostationary meteorological satellite data. The Himawari-8 satellite is the Japanese state-of-the-art geostationary meteorological satellite that has 16 observation channels and has spatial resolutions of 0.5 km (visible) and 2.0 km (near-infrared and infrared) with an time interval of 2.5 minutes around Japan. To estimate the relationship between the satellite brightness temperature and the atmospheric delay amount. Since the InSAR atmospheric delay is principally the same as that in GNSS, we at first compared the Himawari-8 data with the GNSS zenith tropospheric delay data derived from the Japanese dense GNSS network. The comparison of them showed that the band with the wavelength of 6.9 μm had the highest correlation to the GNSS observation. Based on this result, we developed an InSAR atmospheric delay model that uses the Himawari-8 6.9 μm band data. For the model validation, we generated InSAR images from the ESA's C-band Sentinel-1 SLC data with the GAMMA SAR software. We selected two regions around Tokyo and Sapporo (both in Japan) as the test sites because of the less temporal decorrelation. The validation result showed that the delay model reasonably estimate large scale phase variation whose spatial scale was on the order of over 20 km. On the other hand, phase variations of

  10. Sea ice classification using dual polarization SAR data

    International Nuclear Information System (INIS)

    Huiying, Liu; Huadong, Guo; Lu, Zhang

    2014-01-01

    Sea ice is an indicator of climate change and also a threat to the navigation security of ships. Polarimetric SAR images are useful in the sea ice detection and classification. In this paper, backscattering coefficients and texture features derived from dual polarization SAR images are used for sea ice classification. Firstly, the HH image is recalculated based on the angular dependences of sea ice types. Then the effective gray level co-occurrence matrix (GLCM) texture features are selected for the support vector machine (SVM) classification. In the end, because sea ice concentration can provide a better separation of pancake ice from old ice, it is used to improve the SVM result. This method provides a good classification result, compared with the sea ice chart from CIS

  11. Performance Analysis of Satellite Missions for Multi-Temporal SAR Interferometry.

    Science.gov (United States)

    Bovenga, Fabio; Belmonte, Antonella; Refice, Alberto; Pasquariello, Guido; Nutricato, Raffaele; Nitti, Davide O; Chiaradia, Maria T

    2018-04-27

    Multi-temporal InSAR (MTI) applications pose challenges related to the availability of coherent scattering from the ground surface, the complexity of the ground deformations, atmospheric artifacts, and visibility problems related to ground elevation. Nowadays, several satellite missions are available providing interferometric SAR data at different wavelengths, spatial resolutions, and revisit time. A new and interesting opportunity is provided by Sentinel-1, which has a spatial resolution comparable to that of previous ESA C-band sensors, and revisit times improved by up to 6 days. According to these different SAR space-borne missions, the present work discusses current and future opportunities of MTI applications in terms of ground instability monitoring. Issues related to coherent target detection, mean velocity precision, and product geo-location are addressed through a simple theoretical model assuming backscattering mechanisms related to point scatterers. The paper also presents an example of a multi-sensor ground instability investigation over Lesina Marina, a village in Southern Italy lying over a gypsum diapir, where a hydration process, involving the underlying anhydride, causes a smooth uplift and the formation of scattered sinkholes. More than 20 years of MTI SAR data have been processed, coming from both legacy ERS and ENVISAT missions, and latest-generation RADARSAT-2, COSMO-SkyMed, and Sentinel-1A sensors. Results confirm the presence of a rather steady uplift process, with limited to null variations throughout the whole monitored time-period.

  12. Performance Analysis of Satellite Missions for Multi-Temporal SAR Interferometry

    Directory of Open Access Journals (Sweden)

    Fabio Bovenga

    2018-04-01

    Full Text Available Multi-temporal InSAR (MTI applications pose challenges related to the availability of coherent scattering from the ground surface, the complexity of the ground deformations, atmospheric artifacts, and visibility problems related to ground elevation. Nowadays, several satellite missions are available providing interferometric SAR data at different wavelengths, spatial resolutions, and revisit time. A new and interesting opportunity is provided by Sentinel-1, which has a spatial resolution comparable to that of previous ESA C-band sensors, and revisit times improved by up to 6 days. According to these different SAR space-borne missions, the present work discusses current and future opportunities of MTI applications in terms of ground instability monitoring. Issues related to coherent target detection, mean velocity precision, and product geo-location are addressed through a simple theoretical model assuming backscattering mechanisms related to point scatterers. The paper also presents an example of a multi-sensor ground instability investigation over Lesina Marina, a village in Southern Italy lying over a gypsum diapir, where a hydration process, involving the underlying anhydride, causes a smooth uplift and the formation of scattered sinkholes. More than 20 years of MTI SAR data have been processed, coming from both legacy ERS and ENVISAT missions, and latest-generation RADARSAT-2, COSMO-SkyMed, and Sentinel-1A sensors. Results confirm the presence of a rather steady uplift process, with limited to null variations throughout the whole monitored time-period.

  13. 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...

  14. Joint use of multi-orbit high-resolution SAR interferometry for DEM generation in mountainous area

    KAUST Repository

    Zhang, Lu; Jiang, Houjun; Liao, Mingsheng; Balz, Timo; Wang, Teng

    2014-01-01

    SAR interferometry has long been regarded as an effective tool for wide-area topographic mapping in hilly and mountainous areas. However, quality of InSAR DEM product is usually affected by atmospheric disturbances and decorrelation-induced voids, especially for data acquired in repeat-pass mode. In this paper, we proposed an approach for improved topographic mapping by optimal fusion of multi-orbit InSAR DEMs with correction of atmospheric phase screen (APS). An experimental study with highresolution TerraSAR-X and COSMO-SkyMed datasets covering a mountainous area was carried out to demonstrate the effectiveness of the proposed approach. Validation with a reference DEM of scale 1:50,000 indicated that vertical accuracy of the fused DEM can be better than 5 m.

  15. Joint use of multi-orbit high-resolution SAR interferometry for DEM generation in mountainous area

    KAUST Repository

    Zhang, Lu

    2014-07-01

    SAR interferometry has long been regarded as an effective tool for wide-area topographic mapping in hilly and mountainous areas. However, quality of InSAR DEM product is usually affected by atmospheric disturbances and decorrelation-induced voids, especially for data acquired in repeat-pass mode. In this paper, we proposed an approach for improved topographic mapping by optimal fusion of multi-orbit InSAR DEMs with correction of atmospheric phase screen (APS). An experimental study with highresolution TerraSAR-X and COSMO-SkyMed datasets covering a mountainous area was carried out to demonstrate the effectiveness of the proposed approach. Validation with a reference DEM of scale 1:50,000 indicated that vertical accuracy of the fused DEM can be better than 5 m.

  16. Monitoring the ongoing deformation and seasonal behaviour affecting Mosul Dam through space-borne SAR data

    Science.gov (United States)

    Tessari, G.; Riccardi, P.; Pasquali, P.

    2017-12-01

    Monitoring of dam structural health is an important practice to control the structure itself and the water reservoir, to guarantee efficient operation and safety of surrounding areas. Ensuring the longevity of the structure requires the timely detection of any behaviour that could deteriorate the dam and potentially result in its shutdown or failure.The detection and monitoring of surface displacements is increasingly performed through the analysis of satellite Synthetic Aperture Radar (SAR) data, thanks to the non-invasiveness of their acquisition, the possibility to cover large areas in a short time and the new space missions equipped with high spatial resolution sensors. The availability of SAR satellite acquisitions from the early 1990s enables to reconstruct the historical evolution of dam behaviour, defining its key parameters, possibly from its construction to the present. Furthermore, the progress on SAR Interferometry (InSAR) techniques through the development of Differential InSAR (DInSAR) and Advanced stacking techniques (A-DInSAR) allows to obtain accurate velocity maps and displacement time-series.The importance of these techniques emerges when environmental or logistic conditions do not allow to monitor dams applying the traditional geodetic techniques. In such cases, A-DInSAR constitutes a reliable diagnostic tool of dam structural health to avoid any extraordinary failure that may lead to loss of lives.In this contest, an emblematic case will be analysed as test case: the Mosul Dam, the largest Iraqi dam, where monitoring and maintaining are impeded for political controversy, causing possible risks for the population security. In fact, it is considered one of the most dangerous dams in the world because of the erosion of the gypsum rock at the basement and the difficult interventions due to security problems. The dam consists of 113 m tall and 3.4 km long earth-fill embankment-type, with a clay core, and it was completed in 1984.The deformation

  17. On the Design of Radar Corner Reflectors for Deformation Monitoring in Multi-Frequency InSAR

    Directory of Open Access Journals (Sweden)

    Matthew C. Garthwaite

    2017-06-01

    Full Text Available Trihedral corner reflectors are being increasingly used as point targets in deformation monitoring studies using interferometric synthetic aperture radar (InSAR techniques. The frequency and size dependence of the corner reflector Radar Cross Section (RCS means that no single design can perform equally in all the possible imaging modes and radar frequencies available on the currently orbiting Synthetic Aperture Radar (SAR satellites. Therefore, either a corner reflector design tailored to a specific data type or a compromise design for multiple data types is required. In this paper, I outline the practical and theoretical considerations that need to be made when designing appropriate radar targets, with a focus on supporting multi-frequency SAR data. These considerations are tested by performing field experiments on targets of different size using SAR images from TerraSAR-X, COSMO-SkyMed and RADARSAT-2. Phase noise behaviour in SAR images can be estimated by measuring the Signal-to-Clutter ratio (SCR in individual SAR images. The measured SCR of a point target is dependent on its RCS performance and the influence of clutter near to the deployed target. The SCR is used as a metric to estimate the expected InSAR displacement error incurred by the design of each target and to validate these observations against theoretical expectations. I find that triangular trihedral corner reflectors as small as 1 m in dimension can achieve a displacement error magnitude of a tenth of a millimetre or less in medium-resolution X-band data. Much larger corner reflectors (2.5 m or greater are required to achieve the same displacement error magnitude in medium-resolution C-band data. Compromise designs should aim to satisfy the requirements of the lowest SAR frequency to be used, providing that these targets will not saturate the sensor of the highest frequency to be used. Finally, accurate boresight alignment of the corner reflector can be critical to the overall

  18. Ocean Surface Wind Speed of Hurricane Helene Observed by SAR

    DEFF Research Database (Denmark)

    Xu, Qing; Cheng, Yongcun; Li, Xiaofeng

    2011-01-01

    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......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...

  19. Spatiotemporal Characterization of Land Subsidence and Uplift (2009–2010 over Wuhan in Central China Revealed by TerraSAR-X InSAR Analysis

    Directory of Open Access Journals (Sweden)

    Lin Bai

    2016-04-01

    Full Text Available The effects of ground deformation pose a significant geo-hazard to the environment and infrastructure in Wuhan, the most populous city in Central China, in the eastern Jianghan Plain at the intersection of the Yangtze and Han rivers. Prior to this study, however, rates and patterns of region-wide ground deformation in Wuhan were little known. Here we employ multi-temporal SAR interferometry to detect and characterize spatiotemporal variations of ground deformation in major metropolitan areas in Wuhan. A total of twelve TerraSAR-X images acquired during 2009–2010 are used in the InSAR time series analysis. InSAR-derived results are validated by levelling survey measurements and reveal a distinct subsidence pattern within six zones in major commercial and industrial areas, with a maximum subsidence rate up to −67.3 mm/year. A comparison analysis between subsiding patterns and urban developments as well as geological conditions suggests that land subsidence in Wuhan is mainly attributed to anthropogenic activities, natural compaction of soft soil, and karst dissolution of subsurface carbonate rocks. However, anthropogenic activities related to intensive municipal construction and industrial production have more significant impacts on the measured subsidence than natural factors. Moreover, remarkable signals of secular land uplift are found along both banks of the Yangtze River, especially along the southern bank, with deformation rates ranging mostly from +5 mm/year to +17.5 mm/year. A strong temporal correlation is highlighted between the detected displacement evolutions and the water level records of the Yangtze River, inferring that this previously unknown deformation phenomenon is likely related to seasonal fluctuations in water levels of the Yangtze River.

  20. Sensor-Oriented Path Planning for Multiregion Surveillance with a Single Lightweight UAV SAR

    Science.gov (United States)

    Li, Jincheng; Chen, Jie; Wang, Pengbo; Li, Chunsheng

    2018-01-01

    In the surveillance of interested regions by unmanned aerial vehicle (UAV), system performance relies greatly on the motion control strategy of the UAV and the operation characteristics of the onboard sensors. This paper investigates the 2D path planning problem for the lightweight UAV synthetic aperture radar (SAR) system in an environment of multiple regions of interest (ROIs), the sizes of which are comparable to the radar swath width. Taking into account the special requirements of the SAR system on the motion of the platform, we model path planning for UAV SAR as a constrained multiobjective optimization problem (MOP). Based on the fact that the UAV route can be designed in the map image, an image-based path planner is proposed in this paper. First, the neighboring ROIs are merged by the morphological operation. Then, the parts of routes for data collection of the ROIs can be located according to the geometric features of the ROIs and the observation geometry of UAV SAR. Lastly, the route segments for ROIs surveillance are connected by a path planning algorithm named the sampling-based sparse A* search (SSAS) algorithm. Simulation experiments in real scenarios demonstrate that the proposed sensor-oriented path planner can improve the reconnaissance performance of lightweight UAV SAR greatly compared with the conventional zigzag path planner. PMID:29439447

  1. Sensor-Oriented Path Planning for Multiregion Surveillance with a Single Lightweight UAV SAR.

    Science.gov (United States)

    Li, Jincheng; Chen, Jie; Wang, Pengbo; Li, Chunsheng

    2018-02-11

    In the surveillance of interested regions by unmanned aerial vehicle (UAV), system performance relies greatly on the motion control strategy of the UAV and the operation characteristics of the onboard sensors. This paper investigates the 2D path planning problem for the lightweight UAV synthetic aperture radar (SAR) system in an environment of multiple regions of interest (ROIs), the sizes of which are comparable to the radar swath width. Taking into account the special requirements of the SAR system on the motion of the platform, we model path planning for UAV SAR as a constrained multiobjective optimization problem (MOP). Based on the fact that the UAV route can be designed in the map image, an image-based path planner is proposed in this paper. First, the neighboring ROIs are merged by the morphological operation. Then, the parts of routes for data collection of the ROIs can be located according to the geometric features of the ROIs and the observation geometry of UAV SAR. Lastly, the route segments for ROIs surveillance are connected by a path planning algorithm named the sampling-based sparse A* search (SSAS) algorithm. Simulation experiments in real scenarios demonstrate that the proposed sensor-oriented path planner can improve the reconnaissance performance of lightweight UAV SAR greatly compared with the conventional zigzag path planner.

  2. Environmental/Noise Effects on VHF/UHF UWB SAR

    National Research Council Canada - National Science Library

    Ralston, James

    1998-01-01

    This paper presents a straightforward approach to estimating the impact of natural environmental noise on an overall system noise temperature for very high frequency/ultrahigh frequency synthetic aperture radar (VHF/UHF SAR...

  3. Building Damage Estimation by Integration of Seismic Intensity Information and Satellite L-band SAR Imagery

    Directory of Open Access Journals (Sweden)

    Nobuoto Nojima

    2010-09-01

    Full Text Available For a quick and stable estimation of earthquake damaged buildings worldwide, using Phased Array type L-band Synthetic Aperture Radar (PALSAR loaded on the Advanced Land Observing Satellite (ALOS satellite, a model combining the usage of satellite synthetic aperture radar (SAR imagery and Japan Meteorological Agency (JMA-scale seismic intensity is proposed. In order to expand the existing C-band SAR based damage estimation model into L-band SAR, this paper rebuilds a likelihood function for severe damage ratio, on the basis of dataset from Japanese Earth Resource Satellite-1 (JERS-1/SAR (L-band SAR images observed during the 1995 Kobe earthquake and its detailed ground truth data. The model which integrates the fragility functions of building damage in terms of seismic intensity and the proposed likelihood function is then applied to PALSAR images taken over the areas affected by the 2007 earthquake in Pisco, Peru. The accuracy of the proposed damage estimation model is examined by comparing the results of the analyses with field investigations and/or interpretation of high-resolution satellite images.

  4. A strategy for Local Surface Stability Monitoring Using SAR Imagery

    Science.gov (United States)

    Kim, J.; Lan, C. W.; Lin, S. Y.; vanGasselt, S.; Yun, H.

    2017-12-01

    In order to provide sufficient facilities to satisfy a growing number of residents, nowadays there are many constructions and maintenance of infrastructures or buildings undergoing above and below the surface of urban area. In some cases we have learned that disasters might happen if the developments were conducted on unknown or geologically unstable ground or in over-developed areas. To avoid damages caused by such settings, it is essential to perform a regular monitoring scheme to understand the ground stability over the whole urban area. Through long-term monitoring, we firstly aim to observe surface stability over the construction sites. Secondly, we propose to implement an automatic extraction and tracking of suspicious unstable area. To achieve this, we used 12-days-interval C-band Sentinel-1A Synthetic Aperture Radar (SAR) images as the main source to perform regular monitoring. Differential Interferometric SAR (D-InSAR) technique was applied to generate interferograms. Together with the accumulation of updated Sentinel-1A SAR images, time series interferograms were formed accordingly. For the purpose of observing surface stability over known construction sites, the interferograms and the unwrapped products could be used to identify the surface displacement occurring before and after specific events. In addition, Small Baseline Subset (SBAS) and Permanent Scatterers (PS) approaches combining a set of unwrapped D-InSAR interferograms were also applied to derive displacement velocities over long-term periods. For some cases, we conducted the ascending and descending mode time series analysis to decompose three surface migration vectors and to precisely identify the risk pattern. Regarding the extraction of suspicious unstable areas, we propose to develop an automatic pattern recognition algorithm for the identification of specific fringe patterns involving various potential risks. The detected fringes were tracked in the time series interferograms and

  5. Towards assimilation of InSAR data in operational weather models

    Science.gov (United States)

    Mulder, Gert; van Leijen, Freek; Barkmeijer, Jan; de Haan, Siebren; Hanssen, Ramon

    2017-04-01

    InSAR signal delays due to the varying atmospheric refractivity are a potential data source to improve weather models [1]. Especially with the launch of the new Sentinel-1 satellites, which increases data coverage, latency and accessibility, it may become possible to operationalize the assimilation of differential integrated refractivity (DIR) values in numerical weather models. Although studies exist on comparison between InSAR data and weather models [2], the impact of assimilation of DIR values in an operational weather model has never been assessed. In this study we present different ways to assimilate DIR values in an operational weather model and show the first forecast results. There are different possibilities to assimilate InSAR-data in a weather model. For example, (i) absolute DIR values can be derived using additional GNSS zenith or slant delay values, (ii) DIR values can be converted to water vapor pressures, or (iii) water vapor pressures can be derived for different heights by combining GNSS and InSAR data. However, an increasing number of assumptions in these processing steps will increase the uncertainty in the final results. Therefore, we chose to insert the InSAR derived DIR values after minimal additional processing. In this study we use the HARMONIE model [3], which is a spectral, non-hydrostatic model with a resolution of about 2.5 km. Currently, this is the operational model in 11 European countries and based on the AROME model [4]. To assimilate the DIR values in the weather model we use a simple adjustment of the weather parameters over the full slant column to match the DIR values. This is a first step towards a more sophisticated approach based on the 3D-VAR or 4D-VAR schemes [5]. Where both assimilation schemes can correct for different weather parameters simultaneously, and 4D-VAR allow us to assimilate DIR values at the exact moment of satellite overpass instead of the start of the forecast window. The approach will be demonstrated

  6. Episodic inflation of Akutan volcano, Alaska revealed from GPS and InSAR time series

    Science.gov (United States)

    DeGrandpre, K.; Lu, Z.; Wang, T.

    2016-12-01

    Akutan volcano is one of the most active volcanoes located long the Aleutian arc. At least 27 eruptions have been noted since 1790 and an intense swarm of volcano-tectonic earthquakes occurred in 1996. Surface deformation after the 1996 earthquake sequence has been studied using GPS and Interferometric Synthetic Aperture Radar (InSAR) separately, yet models created from these datasets require different mechanisms to produce the observed surface deformation: an inflating Mogi source results in the best approximation of displacement observed from GPS data, whereas an opening dyke is the best fit to deformation measured from InSAR. A recent study using seismic data revealed complex magmatic structures beneath the caldera, suggesting that the surface deformation may reflect more complicated mechanisms that cannot be estimated using one type of data alone. Here we integrate the surface deformation measured from GPS and InSAR to better understand the magma plumbing system beneath Akutan volcano. GPS time-series at 12 stations from 2006 to 2016 were analyzed, and two transient episodes of inflation in 2008 and 2014 were detected. These GPS stations are, however, too sparse to reveal the spatial distribution of the surface deformation. In order to better define the spatial extent of this inflation four tracks of Envisat data acquired during 2003-2010 and one track of TerraSAR-X data acquired from 2010 to 2016 were processed to produce high-resolution maps of surface deformation. These deformation maps show a consistently uplifting area on the northwestern flank of the volcano. We inverted for the source parameters required to produce the inflation using GPS, InSAR, and a dataset of GPS and InSAR measurements combined, to find that a deep Mogi source below a shallow dyke fit these datasets best. From the TerraSAR-X data, we were also able to measure the subsidence inside the summit caldera due to fumarole activity to be as high as 10 mm/yr. The complex spatial and temporal

  7. Ka-band InSAR Imaging and Analysis Based on IMU Data

    Directory of Open Access Journals (Sweden)

    Shi Jun

    2014-02-01

    Full Text Available Compared with other bands, the millimeter wave Interferometric Synthetic Aperture Radar (InSAR has high accuracy and small size, which is a hot topic in InSAR research. On the other hand, shorter wavelength causes difficulties in 2D imaging and interferometric phase extraction. In this study, the imaging and phase performance of the streaming Back Projection (BP method combined with IMU data are analyzed and discussed on the basis of actual Ka-band InSAR data. It is found that because the wavelength of the Ka-band is short, it is more sensitive to the antenna phase-center history. To ensure the phase-preserving capacity, the IMU data must be used with accurate motion error compensation. Furthermore, during data processing, we verify the flat-earth-removing capacity of the BP algorithm that calculates and compensates the master and slave antenna phase centers individually.

  8. Different scale land subsidence and ground fissure monitoring with multiple InSAR techniques over Fenwei basin, China

    Directory of Open Access Journals (Sweden)

    C. Zhao

    2015-11-01

    Full Text Available Fenwei basin, China, composed by several sub-basins, has been suffering severe geo-hazards in last 60 years, including large scale land subsidence and small scale ground fissure, which caused serious infrastructure damages and property losses. In this paper, we apply different InSAR techniques with different SAR data to monitor these hazards. Firstly, combined small baseline subset (SBAS InSAR method and persistent scatterers (PS InSAR method is used to multi-track Envisat ASAR data to retrieve the large scale land subsidence covering entire Fenwei basin, from which different land subsidence magnitudes are analyzed of different sub-basins. Secondly, PS-InSAR method is used to monitor the small scale ground fissure deformation in Yuncheng basin, where different spatial deformation gradient can be clearly discovered. Lastly, different track SAR data are contributed to retrieve two-dimensional deformation in both land subsidence and ground fissure region, Xi'an, China, which can be benefitial to explain the occurrence of ground fissure and the correlation between land subsidence and ground fissure.

  9. Answering the right question - integration of InSAR with other datasets

    Science.gov (United States)

    Holley, Rachel; McCormack, Harry; Burren, Richard

    2014-05-01

    The capabilities of satellite Interferometric Synthetic Aperture Radar (InSAR) are well known, and utilized across a wide range of academic and commercial applications. However there is a tendency, particularly in commercial applications, for users to ask 'What can we study with InSAR?'. When establishing a new technique this approach is important, but InSAR has been possible for 20 years now and, even accounting for new and innovative algorithms, this ground has been thoroughly explored. Too many studies conclude 'We show the ground is moving here, by this much', and mention the wider context as an afterthought. The focus needs to shift towards first asking the right questions - in fields as diverse as hazard awareness, resource optimization, financial considerations and pure scientific enquiry - and then working out how to achieve the best possible answers. Depending on the question, InSAR (and ground deformation more generally) may provide a large or small contribution to the overall solution, and there are usually benefits to integrating a number of techniques to capitalize on the complementary capabilities and provide the most useful measurements. However, there is still a gap between measurements and answers, and unlocking the value of the data relies heavily on appropriate visualization, integrated analysis, communication between technique and application experts, and appropriate use of modelling. We present a number of application examples, and demonstrate how their usefulness can be transformed by moving from a focus on data to answers - integrating complementary geodetic, geophysical and geological datasets and geophysical modeling with appropriate visualization, to enable comprehensive solution-focused interpretation. It will also discuss how forthcoming developments are likely to further advance realisation of the full potential satellite InSAR holds.

  10. A very bright SAR arc: implications for extreme magnetosphere-ionosphere coupling

    Directory of Open Access Journals (Sweden)

    J. Baumgardner

    2008-01-01

    Full Text Available In contrast to the polar aurora visible during geomagnetic storms, stable auroral red (SAR arcs offer a sub-visual manifestation of direct magnetosphere-ionosphere (M-I coupling at midlatitudes. The SAR arc emission at 6300 Å is driven by field-aligned magnetospheric energy transport from ring current/plasmapause locations into the ionosphere-thermosphere system. The first SAR arc was observed at the dawn of the space age (1956, and the typical brightness levels and occurrence patterns obtained from subsequent decades of observations appear to be consistent with the downward heat conduction theory, i.e., heated ambient F-layer electrons excite oxygen atoms to produce a spectrally pure emission. On very rare occasions, a SAR arc has been reported to be at brightness levels visible to the naked eye. Here we report on the first case of a very bright SAR arc (~13 kilo-Rayleighs observed by four diagnostic systems that sampled various aspects of the sub-auroral domain near Millstone Hill, MA, on the night of 29 October 1991: an imaging spectrograph, an all-sky camera, an incoherent scatter radar (ISR, and a DMSP satellite. Simulations of emission using the ISR and DMSP data with the MSIS neutral atmosphere succeed in reproducing the brightness levels observed. This provides a robust confirmation of M-I coupling theory in its most extreme aeronomic form within the innermost magnetosphere (L~2 during a rare superstorm event. The unusually high brightness value appears to be due to the rare occurrence of the heating of dense ionospheric plasma just equatorward of the trough/plasmapause location, in contrast to the more typical heating of the less dense F-layer within the trough.

  11. The Effects of Elevated Specific Conductivity on the Chronic Toxicity of Mining Influenced Streams Using Ceriodaphnia dubia.

    Science.gov (United States)

    Armstead, Mindy Yeager; Bitzer-Creathers, Leah; Wilson, Mandee

    2016-01-01

    Salinization of freshwater ecosystems as a result of human activities has markedly increased in recent years. Much attention is currently directed at evaluating the effects of increased salinity on freshwater biota. In the Central Appalachian region of the eastern United States, specific conductance from alkaline discharges associated with mountain top mining practices has been implicated in macroinvertebrate community declines in streams receiving coal mining discharges. Whole effluent toxicity testing of receiving stream water was used to test the hypothesis that mine discharges are toxic to laboratory test organisms and further, that toxicity is related to ionic concentrations as indicated by conductivity. Chronic toxicity testing using Ceriodaphnia dubia was conducted by contract laboratories at 72 sites with a total of 129 tests over a 3.5 year period. The database was evaluated to determine the ionic composition of mine effluent dominated streams and whether discharge constituents were related to toxicity in C. dubia. As expected, sulfate was found to be the dominant anion in streams receiving mining discharges with bicarbonate variable and sometimes a substantial component of the dissolved solids. Overall, the temporal variability in conductance was low at each site which would indicate fairly stable water quality conditions. Results of the toxicity tests show no relationship between conductance and survival of C. dubia in the mining influenced streams with the traditional toxicity test endpoints. However, consideration of the entire dataset revealed a significant inverse relationship between conductivity and neonate production. While conductivity explained very little of the high variability in the offspring production (r2 = 0.1304), the average numbers of offspring were consistently less than 20 neonates at the highest conductivities.

  12. The Effects of Elevated Specific Conductivity on the Chronic Toxicity of Mining Influenced Streams Using Ceriodaphnia dubia.

    Directory of Open Access Journals (Sweden)

    Mindy Yeager Armstead

    Full Text Available Salinization of freshwater ecosystems as a result of human activities has markedly increased in recent years. Much attention is currently directed at evaluating the effects of increased salinity on freshwater biota. In the Central Appalachian region of the eastern United States, specific conductance from alkaline discharges associated with mountain top mining practices has been implicated in macroinvertebrate community declines in streams receiving coal mining discharges. Whole effluent toxicity testing of receiving stream water was used to test the hypothesis that mine discharges are toxic to laboratory test organisms and further, that toxicity is related to ionic concentrations as indicated by conductivity. Chronic toxicity testing using Ceriodaphnia dubia was conducted by contract laboratories at 72 sites with a total of 129 tests over a 3.5 year period. The database was evaluated to determine the ionic composition of mine effluent dominated streams and whether discharge constituents were related to toxicity in C. dubia. As expected, sulfate was found to be the dominant anion in streams receiving mining discharges with bicarbonate variable and sometimes a substantial component of the dissolved solids. Overall, the temporal variability in conductance was low at each site which would indicate fairly stable water quality conditions. Results of the toxicity tests show no relationship between conductance and survival of C. dubia in the mining influenced streams with the traditional toxicity test endpoints. However, consideration of the entire dataset revealed a significant inverse relationship between conductivity and neonate production. While conductivity explained very little of the high variability in the offspring production (r2 = 0.1304, the average numbers of offspring were consistently less than 20 neonates at the highest conductivities.

  13. IMAGE ENHANCEMENT AND SPECKLE REDUCTION OF FULL POLARIMETRIC SAR DATA BY GAUSSIAN MARKOV RANDOM FIELD

    Directory of Open Access Journals (Sweden)

    M. Mahdian

    2013-09-01

    Full Text Available 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.

  14. Determining the influence of Korean population variation on whole-body average SAR.

    Science.gov (United States)

    Lee, Ae-Kyoung; Choi, Hyung-Do

    2012-05-07

    Compliance of the ICNIRP reference and IEEE action levels with the basic restrictions on whole-body average (WBA) SAR was investigated based on age, physique, and posture under isolated and grounded conditions. First, Korean male models 1, 3, 5, 7, and 20 years of age with body sizes in the 50th percentile were developed and used as the test subjects: 1y(50th), 3y(50th), 5y(50th), 7y(50th), and 20y(50th). The effects of age-dependent dielectric properties due to the water content of the tissue on WBA SAR were analysed, and showed that the changes in WBA SAR are marginal. At the ages of 1, 5, and 20, thin models 1y(10th), 5y(10th), and 20y(10th) with body sizes in the 10th percentile for the horizontal plane were added in order to determine the influence of physical variations of the population. We considered standing postures with arms up and arms down. The WBA SAR for each human model was calculated when exposed to a vertically polarized plane wave in the frequency range of 10 MHz-3 GHz using the finite-difference time-domain method. The evaluated WBA SAR-based safety factor of each model is discussed for exposure to the ICNIRP reference and IEEE action levels. Finally, the lowest external electric field strength required to produce the basic restrictions on the WBA SAR, 0.08 W kg(-1), was obtained. The results showed that the ICNIRP public reference level is not conservative in the frequency range of 20-200 MHz for an arms-up posture, in the range of 40-200 MHz for an arms-down posture, and above 1 GHz for both postures. The IEEE action level is different from the ICNIRP reference level below 30 MHz, where most cases showed a safety factor of less than 50, which is the minimum value compliant with the basic restrictions for exposure to the general public.

  15. OIL SPILL DETECTION AND MONITORING OF ABU DHABI COASTAL ZONE USING KOMPSAT-5 SAR IMAGERY

    OpenAIRE

    H. A. Harahsheh

    2016-01-01

    Abu Dhabi Government endorsed vision for its Maritime Strategy ‘A safe, secure and sustainable maritime domain for Abu Dhabi'. This research study share this vision using the concept of monitoring as tool for marine protection against any possible oil pollution. The best technology to detect and monitor oil pollution and in particularly oil spill is SAR imagery In this case study we chose KOMPSAT-5 SAR. KOMPSAT-5 carries X-band SAR for earth observation, and is capable of day-...

  16. 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...

  17. Stormwater runoff plumes in the Southern California Bight: A comparison study with SAR and MODIS imagery.

    Science.gov (United States)

    Holt, Benjamin; Trinh, Rebecca; Gierach, Michelle M

    2017-05-15

    Stormwater runoff is the largest source of pollution in the Southern California Bight (SCB), resulting from untreated runoff and pollutants from urban watersheds entering the coastal waters after rainstorms. We make use of both satellite SAR and MODIS-Aqua ocean color imagery to examine two different components of runoff plumes, the surface slick and the sediment discharge. We expand on earlier satellite SAR studies by examining an extensive collection of multi-platform SAR imagery, spanning from 1992 to 2014, that provides a more comprehensive view of the plume surface slick characteristics, illustrated with distribution maps of the extent and flow direction of the plumes. The SAR-detected surface plumes are compared with coincident rain and runoff measurements, and with available measured shoreline fecal bacteria loads. We illustrate differences in the detection of SAR surface plumes with the sediment-related discharge plumes derived from MODIS imagery. A conceptual satellite stormwater runoff monitoring approach is presented. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Tie Points Extraction for SAR Images Based on Differential Constraints

    Science.gov (United States)

    Xiong, X.; Jin, G.; Xu, Q.; Zhang, H.

    2018-04-01

    Automatically extracting tie points (TPs) on large-size synthetic aperture radar (SAR) images is still challenging because the efficiency and correct ratio of the image matching need to be improved. This paper proposes an automatic TPs extraction method based on differential constraints for large-size SAR images obtained from approximately parallel tracks, between which the relative geometric distortions are small in azimuth direction and large in range direction. Image pyramids are built firstly, and then corresponding layers of pyramids are matched from the top to the bottom. In the process, the similarity is measured by the normalized cross correlation (NCC) algorithm, which is calculated from a rectangular window with the long side parallel to the azimuth direction. False matches are removed by the differential constrained random sample consensus (DC-RANSAC) algorithm, which appends strong constraints in azimuth direction and weak constraints in range direction. Matching points in the lower pyramid images are predicted with the local bilinear transformation model in range direction. Experiments performed on ENVISAT ASAR and Chinese airborne SAR images validated the efficiency, correct ratio and accuracy of the proposed method.

  19. Integrating SAR with Optical and Thermal Remote Sensing for Operational Near Real-Time Volcano Monitoring

    Science.gov (United States)

    Meyer, F. J.; Webley, P.; Dehn, J.; Arko, S. A.; McAlpin, D. B.

    2013-12-01

    Volcanic eruptions are among the most significant hazards to human society, capable of triggering natural disasters on regional to global scales. In the last decade, remote sensing techniques have become established in operational forecasting, monitoring, and managing of volcanic hazards. Monitoring organizations, like the Alaska Volcano Observatory (AVO), are nowadays heavily relying on remote sensing data from a variety of optical and thermal sensors to provide time-critical hazard information. Despite the high utilization of these remote sensing data to detect and monitor volcanic eruptions, the presence of clouds and a dependence on solar illumination often limit their impact on decision making processes. Synthetic Aperture Radar (SAR) systems are widely believed to be superior to optical sensors in operational monitoring situations, due to the weather and illumination independence of their observations and the sensitivity of SAR to surface changes and deformation. Despite these benefits, the contributions of SAR to operational volcano monitoring have been limited in the past due to (1) high SAR data costs, (2) traditionally long data processing times, and (3) the low temporal sampling frequencies inherent to most SAR systems. In this study, we present improved data access, data processing, and data integration techniques that mitigate some of the above mentioned limitations and allow, for the first time, a meaningful integration of SAR into operational volcano monitoring systems. We will introduce a new database interface that was developed in cooperation with the Alaska Satellite Facility (ASF) and allows for rapid and seamless data access to all of ASF's SAR data holdings. We will also present processing techniques that improve the temporal frequency with which hazard-related products can be produced. These techniques take advantage of modern signal processing technology as well as new radiometric normalization schemes, both enabling the combination of

  20. Detection of oil spills near offshore installations using synthetic aperture radar (SAR)

    International Nuclear Information System (INIS)

    Espedal, H.A.; Johannessen, O.M.

    2000-01-01

    Remote sensing using synthetic aperture radar (SAR) is attracting increasing interest for the detection of oil spills from offshore oil installations. Three systems are already operating and three more are planned. SAR can provide high spatial resolution and is not affected by the time of day or cloud conditions. Examples of images obtained from UK and Norwegian offshore installations are shown and their interpretation are explained. SAR image analysis is used by a satellite-based oil spill monitoring service covering the Norwegian sector of the North Sea and part of the North Sea, the Norwegian Sea and the Baltic Sea. An algorithm has been developed at the Nansen Environmental and Remote Sensing Centre (NERSC) in Norway to help distinguish between oil spills, natural films, current shear zones and rain cells

  1. High-speed railway bridge dynamic measurement based on GB-InSAR technology

    Science.gov (United States)

    Liu, Miao; Ding, Ke-liang; Liu, Xianglei; Song, Zichao

    2015-12-01

    It is an important task to evaluate the safety during the life of bridges using the corresponding vibration parameters. With the advantages of non-contact and high accuracy, the new remote measurement technology of GB-InSAR is suitable to make dynamic measurement for bridges to acquire the vibration parameters. Three key technologies, including stepped frequency-continuous wave technique, synthetic aperture radar and interferometric measurement technique, are introduced in this paper. The GB-InSAR is applied for a high-speed railway bridge to measure of dynamic characteristics with the train passing which can be used to analyze the safety of the monitored bridge. The test results shown that it is an reliable non-contact technique for GB-InSAR to acquire the dynamic vibration parameter for the high-speed railway bridges.

  2. Convolutional neural network using generated data for SAR ATR with limited samples

    Science.gov (United States)

    Cong, Longjian; Gao, Lei; Zhang, Hui; Sun, Peng

    2018-03-01

    Being able to adapt all weather at all times, it has been a hot research topic that using Synthetic Aperture Radar(SAR) for remote sensing. Despite all the well-known advantages of SAR, it is hard to extract features because of its unique imaging methodology, and this challenge attracts the research interest of traditional Automatic Target Recognition(ATR) methods. With the development of deep learning technologies, convolutional neural networks(CNNs) give us another way out to detect and recognize targets, when a huge number of samples are available, but this premise is often not hold, when it comes to monitoring a specific type of ships. In this paper, we propose a method to enhance the performance of Faster R-CNN with limited samples to detect and recognize ships in SAR images.

  3. Applicability of interferometric SAR technology to ground movement and pipeline monitoring

    Science.gov (United States)

    Grivas, Dimitri A.; Bhagvati, Chakravarthy; Schultz, B. C.; Trigg, Alan; Rizkalla, Moness

    1998-03-01

    This paper summarizes the findings of a cooperative effort between NOVA Gas Transmission Ltd. (NGTL), the Italian Natural Gas Transmission Company (SNAM), and Arista International, Inc., to determine whether current remote sensing technologies can be utilized to monitor small-scale ground movements over vast geographical areas. This topic is of interest due to the potential for small ground movements to cause strain accumulation in buried pipeline facilities. Ground movements are difficult to monitor continuously, but their cumulative effect over time can have a significant impact on the safety of buried pipelines. Interferometric synthetic aperture radar (InSAR or SARI) is identified as the most promising technique of those considered. InSAR analysis involves combining multiple images from consecutive passes of a radar imaging platform. The resulting composite image can detect changes as small as 2.5 to 5.0 centimeters (based on current analysis methods and radar satellite data of 5 centimeter wavelength). Research currently in progress shows potential for measuring ground movements as small as a few millimeters. Data needed for InSAR analysis is currently commercially available from four satellites, and additional satellites are planned for launch in the near future. A major conclusion of the present study is that InSAR technology is potentially useful for pipeline integrity monitoring. A pilot project is planned to test operational issues.

  4. B1-based SAR reconstruction using contrast source inversion-electric properties tomography (CSI-EPT)

    NARCIS (Netherlands)

    Balidemaj, Edmond; van den Berg, Cornelis A T; van Lier, A.L.H.M.W.; Nederveen, Aart J; Stalpers, Lukas J A; Crezee, Hans; Remis, Rob F

    Specific absorption rate (SAR) assessment is essential for safety purposes during MR acquisition. Online SAR assessment is not trivial and requires, in addition, knowledge of the electric tissue properties and the electric fields in the human anatomy. In this study, the potential of the recently

  5. B1-based SAR reconstruction using contrast source inversion–electric properties tomography (CSI-EPT)

    NARCIS (Netherlands)

    Balidemaj, E.; van den Berg, CAT; van Lier, ALHMW; Nederveen, AJ; Stalpers, LJA; Crezee, H; Remis, R.F.

    2016-01-01

    Specific absorption rate (SAR) assessment is essential for safety purposes during MR acquisition. Online SAR assessment is not trivial and requires, in addition, knowledge of the electric tissue properties and the electric fields in the human anatomy. In this study, the potential of the recently

  6. Potential of X-Band TerraSAR-X and COSMO-SkyMed SAR Data for the Assessment of Physical Soil Parameters

    Directory of Open Access Journals (Sweden)

    Azza Gorrab

    2015-01-01

    Full Text Available The aim of this paper is to analyze the potential of X-band SAR measurements (COSMO-SkyMed and TerraSAR-X made over bare soils for the estimation of soil moisture and surface geometry parameters at a semi-arid site in Tunisia (North Africa. Radar signals acquired with different configurations (HH and VV polarizations, incidence angles of 26° and 36° are statistically compared with ground measurements (soil moisture and roughness parameters. The radar measurements are found to be highly sensitive to the various soil parameters of interest. A linear relationship is determined for the radar signals as a function of volumetric soil moisture, and a logarithmic correlation is observed between the radar signals and three surface roughness parameters: the root mean square height (Hrms, the parameter Zs = Hrms2/l (where l is the correlation length and the parameter Zg = Hrms × (Hrms/lα (where α is the power of the surface height correlation function. The highest dynamic sensitivity is observed for Zg at high incidence angles. Finally, the performance of different physical and semi-empirical backscattering models (IEM, Baghdadi-calibrated IEM and Dubois models is compared with SAR measurements. The results provide an indication of the limits of validity of the IEM and Dubois models, for various radar configurations and roughness conditions. Considerable improvements in the IEM model performance are observed using the Baghdadi-calibrated version of this model.

  7. Space-borne polarimetric SAR sensors or the golden age of radar polarimetry

    Directory of Open Access Journals (Sweden)

    Pottier E.

    2010-06-01

    Full Text Available SAR Polarimetry represents an active area of research in Active Earth Remote Sensing. This interest is clearly supported by the fact that nowadays there exists, or there will exist in a very next future, a non negligible quantity of launched Polarimetric SAR Spaceborne sensors. The ENVISAT satellite, developed by ESA, was launched on March 2002, and was the first Spaceborne sensor offering an innovative dualpolarization Advanced Synthetic Aperture Radar (ASAR system operating at C-band. The second Polarimetric Spaceborne sensor is ALOS, a Japanese Earth-Observation satellite, developed by JAXA and was launched in January 2006. This mission includes an active L-band polarimetric radar sensor (PALSAR whose highresolution data may be used for environmental and hazard monitoring. The third Polarimetric Spaceborne sensor is TerraSAR-X, a new German radar satellite, developed by DLR, EADS-Astrium and Infoterra GmbH, was launched on June 2007. This sensor carries a dual-polarimetric and high frequency X-Band SAR sensor that can be operated in different modes and offers features that were not available from space before. At least, the Polarimetric Spaceborne sensor, developed by CSA and MDA, and named RADARSAT-2 was launched in December 2007 The Radarsat program was born out the need for effective monitoring of Canada’s icy waters, and some Radarsat-2 capabilities that benefit sea- and river ice applications are the multi-polarization options that will improve ice-edge detection, ice-type discrimination and structure information. The many advances in these different Polarimetric Spaceborne platforms were developed to respond to specific needs for radar data in environmental monitoring applications around the world, like : sea- and river-ice monitoring, marine surveillance, disaster management, oil spill detection, snow monitoring, hydrology, mapping, geology, agriculture, soil characterisation, forestry applications (biomass, allometry, height

  8. Wind Speed Retrieval by Means of X-Band Cosmo-Skymed SAR Data with Application to Coastel Circulation Modeling

    Science.gov (United States)

    Montuori, Antonio; de Ruggiero, Paola; Migliaccio, Maurizio; Pierini, Stefano

    2012-03-01

    In this paper, the capabilities of X-band COSMOSkyMed SAR data are investigated for both wind speed estimation purposes and for the improvement of coastal circulation modeling. The data set consists of 60 X-band Level 1B Multi-Look Ground Detected ScanSAR HugeRegion COSMO-SkyMed SAR data, gathered in the Southern Tyrrhenian Sea during the summer and winter seasons of 2010. Wind speed is estimated by means of a SAR wind speed retrieval based on the azimuth cut-off procedure. Wind direction is provided by means of a SAR retrieval approach based on Discrete Wavelet Transform. After comparison with the provided ground truth data, SAR-derived wind fields and ECMWF data are used to construct a blended wind product regularly sampled in both space and time. The resulting wind field will be used to force the Princeton Ocean Model, which has been implemented in a Southern Tyrrhenian Sea coastal area to simulate wind-driven costal circulation processes.

  9. METH-33 - Performance assessment for the high resolution and wide swath (HRWS) post-Sentinel-1 SAR system

    DEFF Research Database (Denmark)

    Zonno, Mariantonietta; Maria J., Sanjuan-Ferrer,; Lopez-Dekker, Paco

    The next generation, post-Sentinel-1, ESA’s C-band synthetic aperture radar (SAR) system is conceived to provide simultaneously high azimuth resolution and wide swath width (HRWS).There are different ways in which the imaging capabilities of the HRWS SAR system can be exploited, which translate...... or numerical models and, if these are not available, real SAR images as well as numerical algorithms and some explicit simulations of the data and of the inversion process are employed. The tool uses as input the HRWS SAR instrument performance for the different applicable modes and produces as output results...

  10. 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

  11. Integrated Time and Phase Synchronization Strategy for a Multichannel Spaceborne-Stationary Bistatic SAR System

    Directory of Open Access Journals (Sweden)

    Feng Hong

    2016-07-01

    Full Text Available The spatial separation of the transmitter and receiver in Bistatic Synthetic Aperture Radar (BiSAR makes it a promising and useful supplement to a classical Monostatic SAR system (MonoSAR. This paper proposes a novel integrated time and phase synchronization strategy for a multichannel spaceborne-stationary BiSAR system. Firstly, the time synchronization strategy is proposed, which includes Pulse Repetition Frequency (PRF generation under noisy conditions, multichannel calibration and the alignment of the recorded data with the orbital data. Furthermore, the phase synchronization strategy, which fully considers the deteriorative factors in the BiSAR configuration, is well studied. The contribution of the phase synchronization strategy includes two aspects: it not only compensates the phase error, but also improves the Signal to Noise Ratio (SNR of the obtained signals. Specifically, all direct signals on different PRF time can be reconstructed with the shift and phase compensation operation using a reference signal. Besides, since the parameters of the reference signal can be estimated only once using the selected practical direct signal and a priori information, the processing complexity is well reduced. Final imaging results with and without compensation for real data are presented to validate the proposed synchronization strategy.

  12. Quantifying sub-pixel urban impervious surface through fusion of optical and inSAR imagery

    Science.gov (United States)

    Yang, L.; Jiang, L.; Lin, H.; Liao, M.

    2009-01-01

    In this study, we explored the potential to improve urban impervious surface modeling and mapping with the synergistic use of optical and Interferometric Synthetic Aperture Radar (InSAR) imagery. We used a Classification and Regression Tree (CART)-based approach to test the feasibility and accuracy of quantifying Impervious Surface Percentage (ISP) using four spectral bands of SPOT 5 high-resolution geometric (HRG) imagery and three parameters derived from the European Remote Sensing (ERS)-2 Single Look Complex (SLC) SAR image pair. Validated by an independent ISP reference dataset derived from the 33 cm-resolution digital aerial photographs, results show that the addition of InSAR data reduced the ISP modeling error rate from 15.5% to 12.9% and increased the correlation coefficient from 0.71 to 0.77. Spatially, the improvement is especially noted in areas of vacant land and bare ground, which were incorrectly mapped as urban impervious surfaces when using the optical remote sensing data. In addition, the accuracy of ISP prediction using InSAR images alone is only marginally less than that obtained by using SPOT imagery. The finding indicates the potential of using InSAR data for frequent monitoring of urban settings located in cloud-prone areas.

  13. A time series deformation estimation in the NW Himalayas using SBAS InSAR technique

    Science.gov (United States)

    Kumar, V.; Venkataraman, G.

    2012-12-01

    A time series land deformation studies in north western Himalayan region has been presented in this study. Synthetic aperture radar (SAR) interferometry (InSAR) is an important tool for measuring the land displacement caused by different geological processes [1]. Frequent spatial and temporal decorrelation in the Himalayan region is a strong impediment in precise deformation estimation using conventional interferometric SAR approach. In such cases, advanced DInSAR approaches PSInSAR as well as Small base line subset (SBAS) can be used to estimate earth surface deformation. The SBAS technique [2] is a DInSAR approach which uses a twelve or more number of repeat SAR acquisitions in different combinations of a properly chosen data (subsets) for generation of DInSAR interferograms using two pass interferometric approach. Finally it leads to the generation of mean deformation velocity maps and displacement time series. Herein, SBAS algorithm has been used for time series deformation estimation in the NW Himalayan region. ENVISAT ASAR IS2 swath data from 2003 to 2008 have been used for quantifying slow deformation. Himalayan region is a very active tectonic belt and active orogeny play a significant role in land deformation process [3]. Geomorphology in the region is unique and reacts to the climate change adversely bringing with land slides and subsidence. Settlements on the hill slopes are prone to land slides, landslips, rockslides and soil creep. These hazardous features have hampered the over all progress of the region as they obstruct the roads and flow of traffic, break communication, block flowing water in stream and create temporary reservoirs and als