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Sample records for adsorption ratio sar

  1. The effect of zeolite treatment by acids on sodium adsorption ratio of coal seam gas water.

    PubMed

    Wang, Xiaoyu; Ozdemir, Orhan; Hampton, Marc A; Nguyen, Anh V; Do, Duong D

    2012-10-15

    Many coal seam gas (CSG) waters contain a sodium ion concentration which is too high relative to calcium and magnesium ions for environment acceptance. Natural zeolites can be used as a cheap and effective method to control sodium adsorption ratio (SAR, which is a measure of the relative preponderance of sodium to calcium and magnesium) due to its high cation exchange capacity. In this study, a natural zeolite from Queensland was examined for its potential to treat CSG water to remove sodium ions to lower SAR and reduce the pH value. The results demonstrate that acid activated zeolite at 30%wt solid ratio can reduce the sodium content from 563.0 to 182.7 ppm; the pH from 8.74 to 6.95; and SAR from 70.3 to 18.5. Based on the results of the batch experiments, the sodium adsorption capacity of the acid-treated zeolite is three times greater than that of the untreated zeolite. Both the untreated and acid-treated zeolite samples were characterized using zeta potential, surface characterization, DTA/TG and particle size distribution in order to explain their adsorption behaviours.

  2. The effect of zeolite treatment by acids on sodium adsorption ratio of coal seam gas water.

    PubMed

    Wang, Xiaoyu; Ozdemir, Orhan; Hampton, Marc A; Nguyen, Anh V; Do, Duong D

    2012-10-15

    Many coal seam gas (CSG) waters contain a sodium ion concentration which is too high relative to calcium and magnesium ions for environment acceptance. Natural zeolites can be used as a cheap and effective method to control sodium adsorption ratio (SAR, which is a measure of the relative preponderance of sodium to calcium and magnesium) due to its high cation exchange capacity. In this study, a natural zeolite from Queensland was examined for its potential to treat CSG water to remove sodium ions to lower SAR and reduce the pH value. The results demonstrate that acid activated zeolite at 30%wt solid ratio can reduce the sodium content from 563.0 to 182.7 ppm; the pH from 8.74 to 6.95; and SAR from 70.3 to 18.5. Based on the results of the batch experiments, the sodium adsorption capacity of the acid-treated zeolite is three times greater than that of the untreated zeolite. Both the untreated and acid-treated zeolite samples were characterized using zeta potential, surface characterization, DTA/TG and particle size distribution in order to explain their adsorption behaviours. PMID:22841594

  3. Infiltration into cropped soils: effect of rain and sodium adsorption ratio-impacted irrigation water.

    PubMed

    Suarez, Donald L; Wood, James D; Lesch, Scott M

    2008-01-01

    The sodium adsorption ratio (SAR) and salinity criteria for water suitability for irrigation have been developed for conditions where irrigation water is the only water source. It is not clear that these criteria are applicable to environments where there is a combination of rain and irrigation during the growing season. The interaction of rainfall with irrigation water is expected to result in increased sodicity hazard because of the low electrical conductivity of rain. In this study we examined the effects of irrigation waters of SAR 2, 4, 6, 8, and 10 mmol(1/2) L(-1/2) and electrical conductivities of 1 and 2 dS m(-1) on the infiltration rate of two soils with alternating cycles of rain (simulated with a rainfall sprinkler) and irrigation water, separated by drying cycles. The infiltration rate of surface samples from two soils, Kobase silty clay (fine, smectitic, frigid, Torrertic Haplustept) and Glendive very fine sandy loam (coarse-loamy, mixed superactive, calcareous, frigid Aridic Ustifluvent) were evaluated under alfalfa (Medicago sativa) cropped conditions for over 140 d and under full canopy cover. Reductions in infiltration were observed for both soils for SAR above 2, and the reductions became more severe with increasing SAR. Saturated hydraulic conductivity measurements taken from undisturbed cores at the end of the experiment were highly variable, suggesting that in situ infiltration measurements may be preferred when evaluating SAR effects. PMID:18765763

  4. Measured and Estimated Sodium-Adsorption Ratios for Tongue River and its Tributaries, Montana and Wyoming, 2004-06

    USGS Publications Warehouse

    Cannon, M.R.; Nimick, David A.; Cleasby, Thomas E.; Kinsey, Stacy M.; Lambing, John H.

    2007-01-01

    The Tongue River drains an area of about 5,400 square miles and flows northward from its headwaters in the Bighorn National Forest of northeastern Wyoming to join the Yellowstone River at Miles City, Montana. Water from the Tongue River and its tributaries is extensively used for irrigation in both Wyoming and Montana. The Tongue River watershed contains vast coal deposits that are extracted at several surface mines. In some areas of the watershed, the coal beds also contain methane gas (coal-bed methane or natural gas), which has become the focus of intense exploration and development. Production of coal-bed methane requires the pumping of large volumes of ground water from the coal beds to reduce water pressure within the formation and release the stored gas. Water from the coal beds typically is high in sodium and low in calcium and magnesium, resulting in a high sodium-adsorption ratio (SAR). Disposal of ground water with high sodium concentrations into the Tongue River has the potential to increase salinity and SAR of water in the river, and potentially reduce the quality of water for irrigation purposes. This report documents SAR values measured in water samples collected at 12 monitoring sites in the Tongue River watershed and presents regression relations between specific conductance (SC) and SAR at each site for the years 2004-06. SAR in water samples was determined from laboratory-measured concentrations of sodium, calcium, and magnesium. The results of regression analysis indicated that SC and SAR were significantly related (p-values < 0.05) at most sites. The regression relations developed for most monitoring sites in the Tongue River watershed were used with continuous SC data to estimate daily SAR during the 2004 and 2005 irrigation seasons and to estimate 2006 provisional SAR values, which were displayed on the Web in real-time. Water samples were collected and analyzed from seven sites on the main stem of the Tongue River located at: (1) Monarch

  5. Enhancing phosphate adsorption by Mg/Al layered double hydroxide functionalized biochar with different Mg/Al ratios.

    PubMed

    Li, Ronghua; Wang, Jim J; Zhou, Baoyue; Awasthi, Mukesh Kumar; Ali, Amjad; Zhang, Zengqiang; Gaston, Lewis A; Lahori, Altaf Hussain; Mahar, Amanullah

    2016-07-15

    Mg/Al ratio plays a significant role for anion adsorption by Mg/Al-layered double hydroxides (Mg/Al-LDHs) modified biochar. In this study, Mg/Al-LDHs biochar with different Mg/Al ratios (2, 3, 4) were prepared by co-precipitation for phosphate removal from aqueous solution. Factors on phosphate adsorption including Mg/Al ratio, pH, and the presence of other inorganic anions were investigated through batch experiments. Increasing Mg/Al ratio in the Mg/Al-LDHs biochar composites generally enhanced phosphate adsorption with Langmuir adsorption maximum calculated at 81.83mg phosphorous (P) per gram of 4:1Mg/Al-LDHs biochar at pH3.0. The adsorption process was best described by the pseudo-second-order kinetic model. Solution pH had greater effects on the phosphate adsorption by Mg/Al LDHs biochar composites with lower Mg/Al ratios. The presence of other inorganic anions decreased the phosphate adsorption efficiency in the order of F(-) > SO4(2-) > NO2(-) >Cl(-). Phosphate adsorption mechanism involves ion exchange, electrostatic attraction and surface inner-sphere complex formation. Overall, Mg/Al-LDHs biochar composites offer a potential alternative of carbon-based adsorbent for phosphate removal from aqueous solution. PMID:27058131

  6. Double-sided F and Cl adsorptions on graphene at various atomic ratios: Geometric, orientation and electronic structure aspects

    NASA Astrophysics Data System (ADS)

    Widjaja, Hantarto; Jiang, Zhong-Tao; Altarawneh, Mohammednoor; Yin, Chun-Yang; Goh, Bee-Min; Mondinos, Nicholas; Amri, Amun; Dlugogorski, Bogdan Z.

    2016-06-01

    Elemental adsorption on graphene offers an effective procedure in fine-tuning electronic and mechanical properties of graphene. The effects of dopants depend on adsorption site, the degree of coverage as well as on the configuration of the deployed supercell. In this contribution, the density functional theory (DFT) calculations were performed to investigate the electronic structures of F and Cl adsorption (double-sided, top site) on graphene in terms of adsorption orientation, atomic ratios, i.e., from C:F/Cl = 18:2 to C:F/Cl = 2:2. Despite being members of the halogens group, F- and Cl-adsorbed on graphene show contrasting trends. F is adsorbed to graphene more strongly than Cl. F favours full and 25% adsorption coverage, while Cl favours 25% coverage. Both F and Cl cases open band gap (at Fermi energy) at certain atomic concentration coverage, but none creates magnetization.

  7. Adsorption of ribose nucleotides on manganese oxides with varied mn/o ratio: implications for chemical evolution.

    PubMed

    Bhushan, Brij; Shanker, Uma; Kamaluddin

    2011-10-01

    Manganese exists in different oxidation states under different environmental conditions with respect to redox potential. Various forms of manganese oxides, namely, Manganosite (MnO), Bixbyite (Mn(2)O(3)), Hausmannite (Mn(3)O(4)) and Pyrolusite (MnO(2)) were synthesized and their possible role in chemical evolution studied. Adsorption studies of ribose nucleotides (5'-AMP, 5'-GMP, 5'-CMP and 5'-UMP) on these manganese oxides at neutral pH, revealed a higher binding affinity to manganosite (MnO) compared to the other manganese oxides. That manganese oxides having a lower Mn-O ratio show higher binding affinity for the ribonucleotides indirectly implies that such oxides may have provided a surface onto which biomonomers could have been concentrated through selective adsorption. Purine nucleotides were adsorbed to a greater extent compared to the pyrimidine nucleotides. Adsorption data followed Langmuir adsorption isotherms, and X( m ) and K( L ) values were calculated. The nature of the interaction and mechanism was elucidated by infrared spectral studies conducted on the metal-oxide and ribonucleotide-metal-oxide adducts.

  8. Adsorption of Ribose Nucleotides on Manganese Oxides with Varied Mn/O Ratio: Implications for Chemical Evolution

    NASA Astrophysics Data System (ADS)

    Bhushan, Brij; Shanker, Uma; Kamaluddin

    2011-10-01

    Manganese exists in different oxidation states under different environmental conditions with respect to redox potential. Various forms of manganese oxides, namely, Manganosite (MnO), Bixbyite (Mn2O3), Hausmannite (Mn3O4) and Pyrolusite (MnO2) were synthesized and their possible role in chemical evolution studied. Adsorption studies of ribose nucleotides (5'-AMP, 5'-GMP, 5'-CMP and 5'-UMP) on these manganese oxides at neutral pH, revealed a higher binding affinity to manganosite (MnO) compared to the other manganese oxides. That manganese oxides having a lower Mn-O ratio show higher binding affinity for the ribonucleotides indirectly implies that such oxides may have provided a surface onto which biomonomers could have been concentrated through selective adsorption. Purine nucleotides were adsorbed to a greater extent compared to the pyrimidine nucleotides. Adsorption data followed Langmuir adsorption isotherms, and X m and K L values were calculated. The nature of the interaction and mechanism was elucidated by infrared spectral studies conducted on the metal-oxide and ribonucleotide-metal-oxide adducts.

  9. The Effects of Salinity and Sodium Adsorption Ratio on the Water Retention and Hydraulic Conductivity Curves of Soils From The Pampa del Tamarugal, Chile

    NASA Astrophysics Data System (ADS)

    Lagos, M. S.; Munoz, J.; Suarez, F. I.; Fierro, V.; Moreno, C.

    2015-12-01

    The Pampa del Tamarugal is located in the Atacama Desert, the most arid desert of the world. It has important reserves of groundwater, which are probably fed by infiltration coming from the Andes Mountain, with groundwater levels fluctuating between 3 and 10-70 m below the land surface. In zones where shallow groundwater exists, the capillary rise allows to have a permanently moist vadose zone, which sustain native vegetation such as the Tamarugos (Prosopis tamarugo Phil.) and Algarrobos (Prosopis alba Griseb.). The native vegetation relies on the soil moisture and on the evaporative fluxes, which are controlled by the hydrodynamic characteristics of the soils. The soils associated to the salt flats of the Pampa del Tamarugal are a mixture of sands and clays, which have high levels of sulfates, chloride, carbonates, sodium, calcium, magnesium, and potassium, with high pH and electrical conductivity, and low organic matter and cationic exchange capacity. In this research, we are interested in evaluating the impact of salinity and sodium adsorption ratio (SAR) on the hydrodynamic characteristics of the soil, i.e., water retention and hydraulic conductivity curves. Soils were collected from the Pampa del Tamarugal and brought to the laboratory for characterization. The evaporation method (HYPROP, UMS) was used to determine the water retention curve and the hydraulic conductivity curve was estimated combining the evaporation method with direct measurements using a variable head permeameter (KSAT, UMS). It was found that higher sodium concentrations increase the water retention capacity and decrease the soiĺs hydraulic conductivity. These changes occur in the moist range of the hydrodynamic characteristics. The soil's hydraulic properties have significant impact on evaporation fluxes, which is the mayor component of the water balance. Thus, it is important to quantify them and incorporate salt precipitation/dissolution effect on the hydrodynamic properties to correctly

  10. Effects of the aspect ratio on the dye adsorption of ZnO nanorods grown by using a sonochemical method for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Choi, Seok Cheol; Yun, Won Suk; Sohn, Sang Ho; Oh, Sang Jin

    2012-11-01

    Well-aligned ZnO nanorods for the photoelectrode of dye-sensitized solar cells (DSSCs) were grown via a sonochemical method, and the effects of their aspect ratios on the dye adsorption in DSSCs were studied. The control of the aspect ratio of well-aligned ZnO nanorods was performed by tuning the mole concentration of zinc acetate dehydrate in the range of 0.04-0.06M. The dye amounts adsorbed in the ZnO nanorods were estimated from the UV-Visible absorbance by using the Beer-Lambert law. The efficiency of DSSCs with ZnO nanorods was measured to investigate the effects of the aspect ratio of the ZnO nanorods on the dye adsorption properties. A change in the aspect ratio of the ZnO nanorods was founded to yield a change in their dye adsorption ability, resulting in a change in the efficiency of the DSSCs.

  11. Biodegradation and adsorption of C1- and C2-phenanthrenes and C1- and C2-dibenzothiophenes in the presence of clay minerals: effect on forensic diagnostic ratios.

    PubMed

    Ugochukwu, Uzochukwu C; Head, Ian M; Manning, David A C

    2014-07-01

    The impact of modified montmorillonites on adsorption and biodegradation of crude oil C1-phenanthrenes, C1-dibenzothiophenes, C2-phenanthrenes and C2-dibenzothiophenes was investigated in aqueous clay/oil microcosm experiments with a hydrocarbon degrading microorganism community. Consequently, the effect on C1-dibenzothiophenes/C1-phenanthrenes, C2-dibenzothiophenes/C2-phenanthrenes, 2+3-methyldibenzothiophene/4-methyldibenzothiophene and 1-methyldibenzothiophene/4-methyldibenzothiophene ratios commonly used as diagnostic ratios for oil forensic studies was evaluated. The clay mineral samples were treated to produce acid activated montmorillonite, organomontmorillonite and homoionic montmorillonite which were used in this study. The different clay minerals (modified and unmodified) showed varied degrees of biodegradation and adsorption of the C1-phenanthrenes, C1-dibenzothiophenes, C2-phenanthrenes and C2-dibenzothiophenes. The study indicated that as opposed to biodegradation, adsorption has no effect on the diagnostic ratios. Among the diagnostic ratios reviewed, only C2-dibenzothiophenes/C2-phenanthrenes ratio was neither affected by adsorption nor biodegradation making this ratio very useful in forensic studies of oil spills and oil-oil correlation.

  12. SAR peculiarities, ambiguities and constraints

    NASA Astrophysics Data System (ADS)

    Keydel, Wolfgang

    1992-08-01

    A synthetic aperture radar (SAR) is basically a coherent scatterometer that employs a coherent real aperture radar with highly sophisticated data evaluation and image processing capabilities. Therefore, the coherence of the system is very important; furthermore, the keypoints for SAR are data storage, evaluation, and processing. These facts entail peculiarities of SAR and special ambiguities which are different from those arising with real aperture radar (RAR). The objective of this paper is to point out the special peculiarities and ambiguities of SAR in comparison to the corresponding properties of RAR. Main topics in this connection are as follows: basic peculiarities like range dependency of signal to noise ratio; azimuth resolution; influence of platform velocity; range and azimuth ambiguities; pulse repetition frequency limitations; velocity effects; and phase error influence, on SAR-image, that can cause motion compensation problems. All these effects will be explained together with different contrast-equations between the target and clutter signals of SAR and RAR.

  13. Hybrid polarity SAR architecture

    NASA Astrophysics Data System (ADS)

    Raney, R. Keith

    2009-05-01

    A space-based synthetic aperture radar (SAR) designed to provide quantitative information on a global scale implies severe requirements to maximize coverage and to sustain reliable operational calibration. These requirements are best served by the hybrid-polarity architecture, in which the radar transmits in circular polarization, and receives on two orthogonal linear polarizations, coherently, retaining their relative phase. This paper summarizes key attributes of hybrid-polarity dual- and quadrature-polarized SARs, reviews the associated advantages, formalizes conditions under which the signal-to-noise ratio is conserved, and describes the evolution of this architecture from first principles.

  14. The ratio of clay content to total organic carbon content is a useful parameter to predict adsorption of the herbicide butachlor in soils.

    PubMed

    Liu, Zhongzhen; He, Yan; Xu, Jianming; Huang, Panming; Jilani, Ghulam

    2008-03-01

    Thirteen soils collected from 11 provinces in eastern China were used to investigate the butachlor adsorption. The results indicated that the total organic carbon (TOC) content, clay content, amorphous Fe2O3 content, silt content, CEC, and pH had a combined effect on the butachlor sorption on soil. Combination of the data obtained from the 13 soils in the present study with other 23 soil samples reported by other researchers in the literature showed that Koc would be a poor predictive parameter for butachlor adsorption on soils with TOC content higher than 4.0% and lower than 0.2%. The soils with the ratio of clay content to TOC content (RCO) values less than 60 adsorbed butachlor mainly by the partition into soil organic matter matrix. The soils with RCO values higher than 60 apparently adsorbed butachlor by the combination of the partition into soil organic matter matrix and adsorption on clay surface.

  15. SARS Basics

    MedlinePlus

    ... waiting room or office. Top of Page CDC’s response to SARS during the 2003 outbreak CDC worked ... Center to provide round-the-clock coordination and response. Committed more than 800 medical experts and support ...

  16. Ratio

    NASA Astrophysics Data System (ADS)

    Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Studer, Andrew J.; Manuel, James R.; Kimpton, Justin A.

    2014-12-01

    Effects of basicity, B (CaO:SiO2 ratio) on the thermal range, concentration, and formation mechanisms of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter bonding phases have been investigated using an in situ synchrotron X-ray diffraction-based methodology with subsequent Rietveld refinement-based quantitative phase analysis. SFCA and SFCA-I phases are the key bonding materials in iron ore sinter, and improved understanding of the effects of processing parameters such as basicity on their formation and decomposition may assist in improving efficiency of industrial iron ore sintering operations. Increasing basicity significantly increased the thermal range of SFCA-I, from 1363 K to 1533 K (1090 °C to 1260 °C) for a mixture with B = 2.48, to ~1339 K to 1535 K (1066 °C to 1262 °C) for a mixture with B = 3.96, and to ~1323 K to 1593 K (1050 °C to 1320 °C) at B = 4.94. Increasing basicity also increased the amount of SFCA-I formed, from 18 wt pct for the mixture with B = 2.48 to 25 wt pct for the B = 4.94 mixture. Higher basicity of the starting sinter mixture will, therefore, increase the amount of SFCA-I, considered to be more desirable of the two phases. Basicity did not appear to significantly influence the formation mechanism of SFCA-I. It did, however, affect the formation mechanism of SFCA, with the decomposition of SFCA-I coinciding with the formation of a significant amount of additional SFCA in the B = 2.48 and 3.96 mixtures but only a minor amount in the highest basicity mixture. In situ neutron diffraction enabled characterization of the behavior of magnetite after melting of SFCA produced a magnetite plus melt phase assemblage.

  17. Water-quality characteristics, including sodium-adsorption ratios, for four sites in the Powder River drainage basin, Wyoming and Montana, water years 2001-2004

    USGS Publications Warehouse

    Clark, Melanie L.; Mason, Jon P.

    2006-01-01

    The U.S. Geological Survey, in cooperation with the Wyoming Department of Environmental Quality, monitors streams throughout the Powder River structural basin in Wyoming and parts of Montana for potential effects of coalbed natural gas development. Specific conductance and sodium-adsorption ratios may be larger in coalbed waters than in stream waters that may receive the discharge waters. Therefore, continuous water-quality instruments for specific conductance were installed and discrete water-quality samples were collected to characterize water quality during water years 2001-2004 at four sites in the Powder River drainage basin: Powder River at Sussex, Wyoming; Crazy Woman Creek near Arvada, Wyoming; Clear Creek near Arvada, Wyoming; and Powder River at Moorhead, Montana. During water years 2001-2004, the median specific conductance of 2,270 microsiemens per centimeter at 25 degrees Celsius (?S/cm) in discrete samples from the Powder River at Sussex, Wyoming, was larger than the median specific conductance of 1,930 ?S/cm in discrete samples collected downstream from the Powder River at Moorhead, Montana. The median specific conductance was smallest in discrete samples from Clear Creek (1,180 ?S/cm), which has a dilution effect on the specific conductance for the Powder River at Moorhead, Montana. The daily mean specific conductance from continuous water-quality instruments during the irrigation season showed the same spatial pattern as specific conductance values for the discrete samples. Dissolved sodium, sodium-adsorption ratios, and dissolved solids generally showed the same spatial pattern as specific conductance. The largest median sodium concentration (274 milligrams per liter) and the largest range of sodium-adsorption ratios (3.7 to 21) were measured in discrete samples from the Powder River at Sussex, Wyoming. Median concentrations of sodium and sodium-adsorption ratios were substantially smaller in Crazy Woman Creek and Clear Creek, which tend to

  18. Modelling soil sodium and potassium adsorption ratio (SPAR) in the immediate period after a grassland fire in Lithuania.

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Cerda, Artemi; Misiūnė, Ieva

    2015-04-01

    The soil sodium and potassium adsorption ratio (SPAR) is an index that measures the amount of sodium and potassium adsorbed onto clay and organic matter surfaces, in relation to calcium and magnesium. Assess the potential of soil dispersion or flocculation, a process which has implication in soil hydraulic properties and erosion (Sarah, 2004). Depending on severity and the type of ash produced, fire can changes in the immediate period the soil nutrient status (Bodi et al. 2014). Ash releases onto soil surface a large amount of cations, due the high pH. Previous works showed that SPAR from ash slurries is higher than solutions produced from litter (Pereira et al., 2014a). Normally the spatial distribution of topsoil nutrients in the immediate period after the fire is very heterogeneous, due to the different impacts of fire. Thus it is important to identify the most accurate interpolation method in order to identify with better precision the impacts of fire on soil properties. The objective of this work is to test several interpolation methods. The study area is located in near Vilnius (Lithuania) at 54° 42' N, 25° 08 E, 158 masl. Four days after the fire it was designed a plot in a burned area with near Vilnius (Lithuania) at 54° 42' N, 25° 08 E, 158 masl. Twenty five samples were collected from the topsoil. The SPAR index was calculated according to the formula: (Na++K+)/(Ca2++Mg2+)1/2 (Sarah, 2004). Data followed the normal distribution, thus no transformation was required previous to data modelling. Several well know interpolation models were tested, as Inverse Distance to a Weight (IDW) with the power of 1, 2, 3 and 4, Radial Basis Functions (RBF), Inverse Multiquadratic (IMT), Multilog (MTG), Multiquadratic (MTQ), Natural Cubic Spline (NCS) and Thin Plate Spline (TPS) and Local Polynomial (LP) with the power of 1 and 2 and Ordinary Kriging. The best interpolator was the one which had the lowest Root Mean Square Error (RMSE) (Pereira et al., 2014b). The

  19. PHARUS airborne SAR concept

    NASA Astrophysics Data System (ADS)

    Snoeij, Paul; Pouwels, Henk; Koomen, Peter J.; Hoogeboom, Peter

    1995-11-01

    PHARUS (phased array universal SAR) is an airborne SAR concept which is being developed in the Netherlands. The PHARUS system differs from other airborne SARs by the use of a phased array antenna, which provides both for the flexibility in the design as well as for a compact, light-weight instrument that can be carried on small aircraft. The concept allows for the construction of airborne SAR systems on a common generic basis but tailored to specific user needs and can be seen as a preparation for future spaceborne SAR systems using solid state transmitters with electronically steerable phased array antenna. The whole approach is aimed at providing an economic and yet technically sophisticated solution to remote sensing or surveying needs of a specific user. The solid state phased array antenna consists of a collection of radiating patches; the design flexibility for a large part resides in the freedom to choose the number of patches, and thereby the essential radar performance parameters such as resolution and swath width. Another consequence of the use of the phased array antenna is the system's compactness and the possibility to rigidly mount it on a small aircraft. The use of small aircraft of course considerably improves the cost/benefit ratio of the use of airborne SAR. Flight altitude of the system is flexible between about 7,000 and 40,000 feet, giving much operational freedom within the meteo and airspace control limits. In the PHARUS concept the airborne segment is complemented by a ground segment, which consists of a SAR processor, possibly extended by a matching image processing package. (A quick look image is available in real-time on board the aircraft.) The SAR processor is UNIX based and runs on easily available hardware (SUN station). Although the additional image processing software is available, the SAR processing software is nevertheless designed to be able to interface with commercially available image processing software, as well as being able

  20. Coating morphology and surface composition of acrylic terpolymers with pendant catechol, OEG and perfluoroalkyl groups in varying ratio and the effect on protein adsorption.

    PubMed

    Zhong, Jun; Ji, Hua; Duan, Jiang; Tu, Haiyang; Zhang, Aidong

    2016-04-01

    This work aims at developing versatile low-biofouling polymeric coatings by using acrylic terpolymers (DOFs) that bear pendant catechol (D), oligo(ethylene glycol) (O), and perfluoroalkyl (F) groups in varying ratios. The polymers were endowed with the ability to form firmly coatings on virtually any surfaces and undergo surface microphase separation and self-assembly, as revealed by the surface enrichment of F pendants and the morphology variation from irregular solid domains to discrete crater-type aggregates of different size. The effect on protein adsorption was investigated using bovine serum albumin (BSA) and adhesive fibrinogen (Fib) as model proteins. The coating of DOF164 (low F content), which has morphology of discrete crater-type aggregates of ∼ 400 nm in size, adsorbed a least amount of protein but with a highest protein unit activity as determined by SPR and immunosorbent assay; whereas the coating of DOF1612 (high F content) showed a 12.3-fold higher adsorption capacity toward Fib. Interestingly, a 2.2-fold lower adsorption amount but with a 1.8-fold higher unit activity was found for Fib adsorbed on the DOF164 surface than on DOF250 (without F fraction), whose OEG segments being a widely recognized protein compatible material. The features of the DOF164 terpolymer presenting a robust coating ability and a minimal protein adsorption capacity while with a high protein unit activity suggest its potential application as a non-fouling surface-modifier for medical antifouling coatings and as a matrix material for selective protein immobilization and activity preservation in biosensor construction. PMID:26764109

  1. Spaceborne SAR Imaging Algorithm for Coherence Optimized.

    PubMed

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

    2016-01-01

    This paper proposes SAR imaging algorithm with largest coherence based on the existing SAR imaging algorithm. The basic idea of SAR imaging algorithm in imaging processing is that output signal can have maximum signal-to-noise ratio (SNR) by using the optimal imaging parameters. Traditional imaging algorithm can acquire the best focusing effect, but would bring the decoherence phenomenon in subsequent interference process. Algorithm proposed in this paper is that SAR echo adopts consistent imaging parameters in focusing processing. Although the SNR of the output signal is reduced slightly, their coherence is ensured greatly, and finally the interferogram with high quality is obtained. In this paper, two scenes of Envisat ASAR data in Zhangbei are employed to conduct experiment for this algorithm. Compared with the interferogram from the traditional algorithm, the results show that this algorithm is more suitable for SAR interferometry (InSAR) research and application. PMID:26871446

  2. Spaceborne SAR Imaging Algorithm for Coherence Optimized.

    PubMed

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

    2016-01-01

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

  3. Spaceborne SAR Imaging Algorithm for Coherence Optimized

    PubMed Central

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

    2016-01-01

    This paper proposes SAR imaging algorithm with largest coherence based on the existing SAR imaging algorithm. The basic idea of SAR imaging algorithm in imaging processing is that output signal can have maximum signal-to-noise ratio (SNR) by using the optimal imaging parameters. Traditional imaging algorithm can acquire the best focusing effect, but would bring the decoherence phenomenon in subsequent interference process. Algorithm proposed in this paper is that SAR echo adopts consistent imaging parameters in focusing processing. Although the SNR of the output signal is reduced slightly, their coherence is ensured greatly, and finally the interferogram with high quality is obtained. In this paper, two scenes of Envisat ASAR data in Zhangbei are employed to conduct experiment for this algorithm. Compared with the interferogram from the traditional algorithm, the results show that this algorithm is more suitable for SAR interferometry (InSAR) research and application. PMID:26871446

  4. Hybrid-Polarity SAR Architecture

    NASA Astrophysics Data System (ADS)

    Raney, R. K.; Freeman, A.

    2009-04-01

    A space-based synthetic aperture radar (SAR) designed to provide quantitative information on a global scale implies severe requirements to maximize coverage and to sustain reliable operational calibration. These requirements are best served by the hybrid-polarity architecture, in which the radar transmits in circular polarization, and receives on two orthogonal linear polarizations, coherently, retaining their relative phase. This paper reviews those advantages,summarizes key attributes of hybrid-polarity dual- and quadrature-polarized SARs including conditions under which the signal-to-noise ratio is conserved, and describes the evolution of this architecture from first principles.

  5. Effects of Zeolite Structure and Si/Al Ratio on Adsorption Thermodynamics and Intrinsic Kinetics of Monomolecular Cracking and Dehydrogenation of Alkanes over Bronsted Acid Sites

    NASA Astrophysics Data System (ADS)

    Janda, Amber Leigh

    butene products. Theoretical calculations suggest that this effect originates from the adsorption of isobutene at channel intersections, indicating that dehydrogenation occurs with stronger preference for these locations than does cracking. In order to analyze the effects of zeolite structure on monomolecular alkane activation reactions, it is necessary to separate the contributions of the adsorption and reaction steps to observed kinetics. A method is developed in Chapter 3 for obtaining the enthalpy and entropy changes for adsorption of n-alkanes from the gas phase onto Bronsted protons (DeltaH ads·H+ and DeltaSads·H+) using configurational-bias Monte Carlo (CBMC) simulations. In Chapter 4 the effects of zeolite structural confinement on n-butane cracking and dehydrogenation are characterized for zeolites that differ predominately in the size and abundance of cavities. Values of DeltaHads·H+ and DeltaSads·H+ are obtained from CBMC simulations and used to extract intrinsic rates and activation parameters. As DeltaS ads·H+ (a proxy for confinement) becomes more negative, DeltaH ‡int and DeltaS‡int decrease for terminal cracking and dehydrogenation when the channel topology (e.g., straight, sinusoidal) is fixed. This observation, as well as positive values for DeltaS‡int, indicate that the transition states for these reactions resemble the products. Finally, in Chapter 5 the influence of channel and cage topology on n-alkane adsorption are characterized for zeolites and zeotypes with one-dimensional pore systems. When cages are not present, DeltaHads·H+ and DeltaSads·H+ at fixed pore-limiting diameter (PLD; the diameter of the largest sphere that can traverse the pores) decrease in magnitude as the ratio of the smallest to largest channel diameter decreases and the pore become less circular. The higher entropy of alkanes in non-circular pores is attributed to greater freedom of movement and can cause the free energy to be lower in these environments relative

  6. Dynamics of Random Sequential Adsorption (RSA) of linear chains consisting of n circular discs - Role of aspect ratio and departure from convexity

    NASA Astrophysics Data System (ADS)

    Shelke, Pradip B.; Limaye, A. V.

    2015-07-01

    We study Random Sequential Adsorption (RSA) of linear chains consisting of n circular discs on a two-dimensional continuum substrate. The study has been carried out for n = 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 50, 70, 100 and 300. For all values of n, instantaneous coverage, Θ(t), in late time regime, is found to approach to jammed state coverage, Θ(∞), in a power law fashion, Θ(∞) - Θ(t) ~ t- p. It is observed that, with the increase in n, the exponent p goes on decreasing from the value 0.33 for n = 2 to the value 0.20 for n = 20 and then again starts rising to reach the value of 0.33 for large n. It is also found that for n ≤ 20, the exponent p has near perfect correlation with the coefficient of departure from convexity. On the other hand the jammed state coverage Θ(∞) is found to depend both on the coefficient of departure from convexity as well as on the aspect ratio of the chain.

  7. Analysis of the biological response of endothelial and fibroblast cells cultured on synthetic scaffolds with various hydrophilic/hydrophobic ratios: influence of fibronectin adsorption and conformation.

    PubMed

    Campillo-Fernández, Alberto J; Unger, Ronald E; Peters, Kirsten; Halstenberg, Sven; Santos, Marina; Salmerón Sánchez, Manuel; Meseguer Dueñas, Jose Maria; Monleón Pradas, Manuel; Gómez Ribelles, Jose Luis; Kirkpatrick, C James

    2009-06-01

    In this study we developed polymer scaffolds intended as anchorage rings for cornea prostheses among other applications, and examined their cell compatibility. In particular, a series of interconnected porous polymer scaffolds with pore sizes from 80 to 110 microns were manufactured varying the ratio of hydrophobic to hydrophilic monomeric units along the polymer chains. Further, the effects of fibronectin precoating, a physiological adhesion molecule, were tested. The interactions between the normal human fibroblast cell line MRC-5 and primary human umbilical vein endothelial cells (HUVECs) with the scaffold surfaces were evaluated. Adhesion and growth of the cells was examined by confocal laser scanning microscopy. Whereas MRC-5 fibroblasts showed adhesion and spreading to the scaffolds without any precoating, HUVECs required a fibronectin precoating for adhesion and spreading. Although both cell types attached and spread on scaffold surfaces with a content of up to a 20% hydrophilic monomers, cell adhesion, spreading, and proliferation increased with increasing hydrophobicity of the substrate. This effect is likely due to better adsorption of serum proteins to hydrophobic substrates, which then facilitate cell adhesion. In fact, atomic force microscopy measurements of fibronectin on surfaces representative of our scaffolds revealed that the amount of fibronectin adsorption correlated directly with the hydrophobicity of the surface. Besides cell adhesion we also examined the inflammatory state of HUVECs in contact with the scaffolds. Typical patterns of platelet/endothelial cell adhesion molecule-1 expression were observed at intercellular boarders. HUVECs adhering on the scaffolds retained their proinflammatory response potential as shown by E-selectin mRNA expression after stimulation with lipopolyssacharide (LPS). The proinflammatory activation occurred in most of the cells, thus confirming the presence of a functionally intact endothelium. Little or no

  8. SAR Product Control Software

    NASA Astrophysics Data System (ADS)

    Meadows, P. J.; Hounam, D.; Rye, A. J.; Rosich, B.; Börner, T.; Closa, J.; Schättler, B.; Smith, P. J.; Zink, M.

    2003-03-01

    As SAR instruments and their operating modes become more complex, as new applications place more and more demands on image quality and as our understanding of their imperfections becomes more sophisticated, there is increasing recognition that SAR data quality has to be controlled more completely to keep pace. The SAR product CONtrol software (SARCON) is a comprehensive SAR product control software suite tailored to the latest generation of SAR sensors. SARCON profits from the most up-to-date thinking on SAR image performance derived from other spaceborne and airborne SAR projects and is based on the newest applications. This paper gives an overview of the structure and the features of this new software tool, which is a product of a co-operation between teams at BAE SYSTEMS Advanced Technology Centre and DLR under contract to ESA (ESRIN). Work on SARCON began in 1999 and is continuing.

  9. SAR change detection MTI

    NASA Astrophysics Data System (ADS)

    Scarborough, Steven; Lemanski, Christopher; Nichols, Howard; Owirka, Gregory; Minardi, Michael; Hale, Todd

    2006-05-01

    This paper examines the theory, application, and results of using single-channel synthetic aperture radar (SAR) data with Moving Reference Processing (MRP) to focus and geolocate moving targets. Moving targets within a standard SAR imaging scene are defocused, displaced, or completely missing in the final image. Building on previous research at AFRL, the SAR-MRP method focuses and geolocates moving targets by reprocessing the SAR data to focus the movers rather than the stationary clutter. SAR change detection is used so that target detection and focusing is performed more robustly. In the cases where moving target returns possess the same range versus slow-time histories, a geolocation ambiguity results. This ambiguity can be resolved in a number of ways. This paper concludes by applying the SAR-MRP method to high-frequency radar measurements from persistent continuous-dwell SAR observations of a moving target.

  10. Real time SAR processing

    NASA Technical Reports Server (NTRS)

    Premkumar, A. B.; Purviance, J. E.

    1990-01-01

    A simplified model for the SAR imaging problem is presented. The model is based on the geometry of the SAR system. Using this model an expression for the entire phase history of the received SAR signal is formulated. From the phase history, it is shown that the range and the azimuth coordinates for a point target image can be obtained by processing the phase information during the intrapulse and interpulse periods respectively. An architecture for a VLSI implementation for the SAR signal processor is presented which generates images in real time. The architecture uses a small number of chips, a new correlation processor, and an efficient azimuth correlation process.

  11. SAR calibration technology review

    NASA Technical Reports Server (NTRS)

    Walker, J. L.; Larson, R. W.

    1981-01-01

    Synthetic Aperture Radar (SAR) calibration technology including a general description of the primary calibration techniques and some of the factors which affect the performance of calibrated SAR systems are reviewed. The use of reference reflectors for measurement of the total system transfer function along with an on-board calibration signal generator for monitoring the temporal variations of the receiver to processor output is a practical approach for SAR calibration. However, preliminary error analysis and previous experimental measurements indicate that reflectivity measurement accuracies of better than 3 dB will be difficult to achieve. This is not adequate for many applications and, therefore, improved end-to-end SAR calibration techniques are required.

  12. Detecting slow moving targets in SAR images

    NASA Astrophysics Data System (ADS)

    Linnehan, Robert; Perlovsky, Leonid; Mutz, Chris W.; Schindler, John

    2004-08-01

    Ground moving target indication (GMTI) radars can detect slow-moving targets if their velocities are high enough to produce distinguishable Doppler frequencies. However, no reliable technique is currently available to detect targets that fall below the minimum detectable velocity (MDV) of GMTI radars. In synthetic aperture radar (SAR) images, detection of moving targets is difficult because of target smear due to motion, which could make low-RCS targets fall below stationary ground clutter. Several techniques for SAR imaging of moving targets have been discussed in the literature. These techniques require sufficient signal-to-clutter ratio (SCR) and adequate MDV for pre-detection. Other techniques require complex changes in hardware. Extracting the maximum information from SAR image data is possible using adaptive, model-based approaches. However, these approaches lead to computational complexity, which exceeds current processing power for more than a single object in an image. This combinatorial complexity is due to the need for having to consider a large number of combinations between multiple target models and the data, while estimating unknown parameters of the target models. We are developing a technique for detecting slow-moving targets in SAR images with low signal-to-clutter ratio, without minimal velocity requirements, and without combinatorial complexity. This paper briefly summarizes the difficulties related to current model-based detection algorithms. A new concept, dynamic logic, is introduced along with an algorithm suitable for the detection of very slow-moving targets in SAR images. This new mathematical technique is inspired by the analysis of biological systems, like the human brain, which combines conceptual understanding with emotional evaluation and overcomes the combinatorial complexity of model-based techniques.

  13. Sodic hazard: the effect of SAR and salinity in soils and overburden materials

    SciTech Connect

    Jurinak, J.J.; Amrhein, C.; Wagenet, R.J.

    1984-03-01

    The authors studied the effect of salinity and sodium adsorption ratio (SAR) on the modified Gapon selectivity coefficient (k/sub g/') using Yolo loam soil and two (sodic) coal mine overburden materials designated surface and deep. The SAR treatments varied in value from 5 to 80 (mmol/L)/sup 1/2/ in an electrolyte solution (NaCl + CaCl/sub 2/) concentration range of 10 to 500 meq/L. When all treatment effects were combined, the k/sub g/' values were 0.0097, 0.0087, and 0.0079 (mmol/L)/sub -1/2/ for Yolo loam, surface, and deep overburden, respectively. In contrast to the other two systems, the deep overburden exhibited a steadily declining value of k/sub g/' (0.014 to 0.0055 (mmol/L)/sup -1/2/ with increasing electrolyte concentration. In all cases the k/sub g/' values were found to be less than the commonly used value of 0.015 (mmol/L)/sup -1/2/. 13 references, 5 figures, 7 tables.

  14. Polarization effects and multipolarization SAR

    NASA Technical Reports Server (NTRS)

    Freeman, Anthony

    1992-01-01

    Imaging radar polarimeters are usually implemented using a Synthetic Aperture Radar (SAR) approach to give a high resolution image in two dimensions: range and azimuth. For each pixel in the image a polarimetric SAR gives sufficient information to characterize the polarimetric scattering properties of the imaged area (or target) as seen by the radar. Using a polarimetric SAR system as opposed to a single-polarization SAR system provides significantly more information about the target scattering mechanisms and allows better discrimination between different types of surfaces. In these notes a brief overview of SAR polarimetry is offered. The notes are intended as a text to accompany a lecture on SAR polarimetry as part of an AGARD-NATO course. Covered in the notes are the following: the polarization properties of electromagnetic waves; the concepts of radar scattering and measuring radar backscatter with a SAR; polarization synthesis; scattering matrix, Stokes matrix, and covariance matrix representations of polarimetric SAR data; polarization signature plots; design and calibration of polarimetric SAR systems; polarization filtering for target detection; fitting a simple model to polarimetric SAR measurements of naturally occurring features; and supervised classification of polarimetric SAR data.

  15. Bistatic SAR: Proof of Concept.

    SciTech Connect

    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.

  16. A Time Domain Along-Track SAR Interferometry Method

    NASA Astrophysics Data System (ADS)

    Cao, N.; Lee, H.; Jung, H. C.

    2015-12-01

    Differential interferometric synthetic aperture radar (DInSAR) has already been proven to be a useful technique for measuring ground displacement at millimeter level. One major drawback of traditional DInSAR technique is that only 1-D deformation in slant range direction can be detected. In order to obtain along-track displacement using a single InSAR pair, two major attempts have been made. The first one is based on cross-correlation between two SAR amplitude images. The second attempt is based on split-beam processing to generate two SAR images from forward- and backward-looking beams. Comparing with the former method, this multiple-aperture SAR interferometry (MAI) can achieve much better measurement accuracy. The major drawback of the MAI method is degraded signal to noise ratio (SNR) and along-track resolution since total along-track integration time decreases in the split-beam procedure. In order to improve the SNR and along-track resolution as well as to extract the terrain displacement in the along-track direction, a time domain along-track SAR interferometry method is proposed in this study. Using traditional time domain backprojection method, the phase component corresponding to slant range direction offset can be estimated and removed from the range compressed SAR signal. Then a phase estimation procedure is implemented to obtain the phase component in the along-track direction. Using ALOS PALSAR data over Kilauea Volcano area in Hawai'i, our experimental results demonstrate the improved performance of the proposed method in extracting 2-D terrain deformation map from one pair of SAR images.

  17. Alaska SAR processor implementation of E-ERS-1

    NASA Technical Reports Server (NTRS)

    Cuddy, David; Chen, Ming-Je; Bicknell, Tom

    1992-01-01

    The synthetic aperture radar (SAR) data processing algorithm used by the Alaska SAR Facility (ASF) for the European Space Agency's first Remote-Sensing Satellite (E-ERS-1) SAR data are examined. Preprocessing highlights two features: signal measurement, which includes signal-to-noise ratio, replica measurement, and noise measurement; and Doppler measurement, which includes clutter lock and autofocus. The custom pipeline architecture performs the main processing with controls at the input interface, range correlator, corner-turn memory, azimuth correlator, and multi-look memory. The control software employs a flexible control scheme. The Committee on Earth Observation Satellites (CEOS) format encapsulates the ASF products. System performance for SAR image processing of E-ERS-1 data is reviewed.

  18. Analysis of Multipath Pixels in SAR Images

    NASA Astrophysics Data System (ADS)

    Zhao, J. W.; Wu, J. C.; Ding, X. L.; Zhang, L.; Hu, F. M.

    2016-06-01

    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, permittivity)which 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.

  19. 3D SAR approach to IF SAR processing

    NASA Astrophysics Data System (ADS)

    Doerry, Armin W.; Bickel, Doug

    2000-08-01

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

  20. Hospital Preparedness and SARS

    PubMed Central

    Wallington, Tamara; Rutledge, Tim; Mederski, Barbara; Rose, Keith; Kwolek, Sue; McRitchie, Donna; Ali, Azra; Wolff, Bryan; White, Diane; Glassman, Edward; Ofner, Marianna; Low, Don E.; Berger, Lisa; McGeer, Allison; Wong, Tom; Baron, David; Berall, Glenn

    2004-01-01

    On May 23, 2003, Toronto experienced the second phase of a severe acute respiratory syndrome (SARS) outbreak. Ninety cases were confirmed, and >620 potential cases were managed. More than 9,000 persons had contact with confirmed or potential case-patients; many required quarantine. The main hospital involved during the second outbreak was North York General Hospital. We review this hospital’s response to, and management of, this outbreak, including such factors as building preparation and engineering, personnel, departmental workload, policies and documentation, infection control, personal protective equipment, training and education, public health, management and administration, follow-up of SARS patients, and psychological and psychosocial management and research. We also make recommendations for other institutions to prepare for future outbreaks, regardless of their origin. PMID:15200807

  1. Circular SAR GMTI

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  2. Wetland InSAR

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  3. Random sequential adsorption on fractals.

    PubMed

    Ciesla, Michal; Barbasz, Jakub

    2012-07-28

    Irreversible adsorption of spheres on flat collectors having dimension d < 2 is studied. Molecules are adsorbed on Sierpinski's triangle and carpet-like fractals (1 < d < 2), and on general Cantor set (d < 1). Adsorption process is modeled numerically using random sequential adsorption (RSA) algorithm. The paper concentrates on measurement of fundamental properties of coverages, i.e., maximal random coverage ratio and density autocorrelation function, as well as RSA kinetics. Obtained results allow to improve phenomenological relation between maximal random coverage ratio and collector dimension. Moreover, simulations show that, in general, most of known dimensional properties of adsorbed monolayers are valid for non-integer dimensions.

  4. SAR-based vibrometry using the fractional Fourier transform

    NASA Astrophysics Data System (ADS)

    Campbell, Justin B.; Wang, Qi; Ade-Bello, Jelili; Caudana, Humberto; Trujillo, Nicole B.; Bhatta, Ishwor; Dunkel, Ralf; Atwood, Thomas; Doerry, Armin; Gerstle, Walter H.; Santhanam, Balu; Hayat, Majeed M.

    2015-05-01

    A fundamental assumption when applying Synthetic Aperture Radar (SAR) to a ground scene is that all targets are motionless. If a target is not stationary, but instead vibrating in the scene, it will introduce a non-stationary phase modulation, termed the micro-Doppler effect, into the returned SAR signals. Previously, the authors proposed a pseudosubspace method, a modification to the Discrete Fractional Fourier Transform (DFRFT), which demonstrated success for estimating the instantaneous accelerations of vibrating objects. However, this method may not yield reliable results when clutter in the SAR image is strong. Simulations and experimental results have shown that the DFRFT method can yield reliable results when the signal-to-clutter ratio (SCR) > 8 dB. Here, we provide the capability to determine a target's frequency and amplitude in a low SCR environment by presenting two methods that can perform vibration estimations when SCR < 3 dB. The first method is a variation and continuation of the subspace approach proposed previously in conjunction with the DFRFT. In the second method, we employ the dual-beam SAR collection architecture combined with the extended Kalman filter (EKF) to extract information from the returned SAR signals about the vibrating target. We also show the potential for extending this SAR-based capability to remotely detect and classify objects housed inside buildings or other cover based on knowing the location of vibrations as well as the vibration histories of the vibrating structures that house the vibrating objects.

  5. Recovering Seasat SAR Data

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  6. Analytical SAR-GMTI principles

    NASA Astrophysics Data System (ADS)

    Soumekh, Mehrdad; Majumder, Uttam K.; Barnes, Christopher; Sobota, David; Minardi, Michael

    2016-05-01

    This paper provides analytical principles to relate the signature of a moving target to parameters in a SAR system. Our objective is to establish analytical tools that could predict the shift and smearing of a moving target in a subaperture SAR image. Hence, a user could identify the system parameters such as the coherent processing interval for a subaperture that is suitable to localize the signature of a moving target for detection, tracking and geolocating the moving target. The paper begins by outlining two well-known SAR data collection methods to detect moving targets. One uses a scanning beam in the azimuth domain with a relatively high PRF to separate the moving targets and the stationary background (clutter); this is also known as Doppler Beam Sharpening. The other scheme uses two receivers along the track to null the clutter and, thus, provide GMTI. We also present results on implementing our SAR-GMTI analytical principles for the anticipated shift and smearing of a moving target in a simulated code. The code would provide a tool for the user to change the SAR system and moving target parameters, and predict the properties of a moving target signature in a subaperture SAR image for a scene that is composed of both stationary and moving targets. Hence, the SAR simulation and imaging code could be used to demonstrate the validity and accuracy of the above analytical principles to predict the properties of a moving target signature in a subaperture SAR image.

  7. Atypical SARS in Geriatric Patient

    PubMed Central

    Oh, Helen M.L.; Hui, K.P.; Lien, Christopher T.C.; Narendran, K.; Heng, B.H.; Ling, A.E.

    2004-01-01

    We describe an atypical presentation of severe acute respiratory syndrome (SARS) in a geriatric patient with multiple coexisting conditions. Interpretation of radiographic changes was confounded by cardiac failure, with resolution of fever causing delayed diagnosis and a cluster of cases. SARS should be considered even if a contact history is unavailable, during an ongoing outbreak. PMID:15030694

  8. Review of bats and SARS.

    PubMed

    Wang, Lin-Fa; Shi, Zhengli; Zhang, Shuyi; Field, Hume; Daszak, Peter; Eaton, Bryan T

    2006-12-01

    Bats have been identified as a natural reservoir for an increasing number of emerging zoonotic viruses, including henipaviruses and variants of rabies viruses. Recently, we and another group independently identified several horseshoe bat species (genus Rhinolophus) as the reservoir host for a large number of viruses that have a close genetic relationship with the coronavirus associated with severe acute respiratory syndrome (SARS). Our current research focused on the identification of the reservoir species for the progenitor virus of the SARS coronaviruses responsible for outbreaks during 2002-2003 and 2003-2004. In addition to SARS-like coronaviruses, many other novel bat coronaviruses, which belong to groups 1 and 2 of the 3 existing coronavirus groups, have been detected by PCR. The discovery of bat SARS-like coronaviruses and the great genetic diversity of coronaviruses in bats have shed new light on the origin and transmission of SARS coronaviruses.

  9. Review of Bats and SARS

    PubMed Central

    Shi, Zhengli; Zhang, Shuyi; Field, Hume; Daszak, Peter; Eaton, Bryan T.

    2006-01-01

    Bats have been identified as a natural reservoir for an increasing number of emerging zoonotic viruses, including henipaviruses and variants of rabies viruses. Recently, we and another group independently identified several horseshoe bat species (genus Rhinolophus) as the reservoir host for a large number of viruses that have a close genetic relationship with the coronavirus associated with severe acute respiratory syndrome (SARS). Our current research focused on the identification of the reservoir species for the progenitor virus of the SARS coronaviruses responsible for outbreaks during 2002–2003 and 2003–2004. In addition to SARS-like coronaviruses, many other novel bat coronaviruses, which belong to groups 1 and 2 of the 3 existing coronavirus groups, have been detected by PCR. The discovery of bat SARS-like coronaviruses and the great genetic diversity of coronaviruses in bats have shed new light on the origin and transmission of SARS coronaviruses. PMID:17326933

  10. Bistatic SAR: Imagery & Image Products.

    SciTech Connect

    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.

  11. Polymer adsorption

    NASA Astrophysics Data System (ADS)

    Joanny, Jean-Francois

    2008-03-01

    The aim of this talk is to review Pierre-Gilles deGennes' work on polymer adsorption and the impact that it has now in our understanding of this problem. We will first present the self-consistent mean-field theory and its applications to adsorption and depletion. De Gennes most important contribution is probably the derivation of the self-similar power law density profile for adsorbed polymer layers that we will present next, emphasizing the differences between the tail sections and the loop sections of the adsorbed polymers. We will then discuss the kinetics of polymer adsorption and the penetration of a new polymer chain in an adsobed layer that DeGennes described very elegantly in analogy with a quantum tunneling problem. Finally, we will discuss the role of polymer adsorption for colloid stabilization.

  12. Anatomy of a SAR impulse response.

    SciTech Connect

    Doerry, Armin Walter

    2007-08-01

    A principal measure of Synthetic Aperture Radar (SAR) image quality is the manifestation in the SAR image of a spatial impulse, that is, the SAR's Impulse Response (IPR). IPR requirements direct certain design decisions in a SAR. Anomalies in the IPR can point to specific anomalous behavior in the radar's hardware and/or software.

  13. Studies of ice sheet hydrology using SAR

    NASA Technical Reports Server (NTRS)

    Bindschadler, R. A.; Vornberger, P. L.

    1989-01-01

    Analysis of SAR data of the Greenland ice sheet in summer and winter suggest the use of SAR to monitor the temporal hydrology of ice sheets. Comparisons of each SAR data set with summer Landsat TM imagery show an areal-positive correlation with summer SAR data and a negative correlation with winter SAR data. It is proposed that the summer SAR data are most sensitive to the variable concentrations of free water in the surface snow and that the winter SAR data indicate variations in snow grain size.

  14. ERS-1 SAR data processing

    NASA Technical Reports Server (NTRS)

    Leung, K.; Bicknell, T.; Vines, K.

    1986-01-01

    To take full advantage of the synthetic aperature radar (SAR) to be flown on board the European Space Agency's Remote Sensing Satellite (ERS-1) (1989) and the Canadian Radarsat (1990), the implementation of a receiving station in Alaska is being studied to gather and process SAR data pertaining in particular to regions within the station's range of reception. The current SAR data processing requirement is estimated to be on the order of 5 minutes per day. The Interim Digital Sar Processor (IDP) which was under continual development through Seasat (1978) and SIR-B (1984) can process slightly more than 2 minutes of ERS-1 data per day. On the other hand, the Advanced Digital SAR Processore (ADSP), currently under development for the Shuttle Imaging Radar C (SIR-C, 1988) and the Venus Radar Mapper, (VMR, 1988), is capable of processing ERS-1 SAR data at a real time rate. To better suit the anticipated ERS-1 SAR data processing requirement, both a modified IDP and an ADSP derivative are being examined. For the modified IDP, a pipelined architecture is proposed for the mini-computer plus array processor arrangement to improve throughout. For the ADSP derivative, a simplified version is proposed to enhance ease of implementation and maintainability while maintaing real time throughput rates. These processing systems are discussed and evaluated.

  15. Synthetic Aperture Radar (SAR) data processing

    NASA Technical Reports Server (NTRS)

    Beckner, F. L.; Ahr, H. A.; Ausherman, D. A.; Cutrona, L. J.; Francisco, S.; Harrison, R. E.; Heuser, J. S.; Jordan, R. L.; Justus, J.; Manning, B.

    1978-01-01

    The available and optimal methods for generating SAR imagery for NASA applications were identified. The SAR image quality and data processing requirements associated with these applications were studied. Mathematical operations and algorithms required to process sensor data into SAR imagery were defined. The architecture of SAR image formation processors was discussed, and technology necessary to implement the SAR data processors used in both general purpose and dedicated imaging systems was addressed.

  16. Design of a monopulse SAR system to determine elevation angles

    NASA Technical Reports Server (NTRS)

    Oettl, H.; Zink, M.; Zeller, K. H.; Freeman, A.

    1992-01-01

    Terrain height variations in mountainous areas cause problems in radiometric corrections of synthetic aperture radar (SAR) images. To determine the elevation angle and the height at the different parts of an image, an application of the monopulse principle is proposed. From the ratios of images radiometrically modulated by the difference and sum antenna pattern in range it is possible to calculate the appropriate elevation angle at any point in the image. Design considerations for a corresponding airborne SAR-system are presented, and some estimates of error influences (e.g., ambiguities), expected performance and precision in topographic mapping are given.

  17. Earth observing SAR data processing systems at the Jet Propulsion Laboratory - Seasat to EOS SAR

    NASA Technical Reports Server (NTRS)

    Nichols, David A.; Curlander, John C.

    1991-01-01

    The evolution of SAR digital data processing and management ground systems developed at the JPL for earth science missions is discussed. Attention is given to the SAR ground data system requirements, the early data processing systems, the Seasat SAR system, and the SIR-B data processing system. Special consideration is given to two currently operational SAR data systems: the JPL aircraft SAR processing system that flies on the NASA DC-8 and the Alaska SAR Facility at Fairbanks.

  18. High-Level Performance Modeling of SAR Systems

    NASA Technical Reports Server (NTRS)

    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.

  19. Thermal noise removal in hybrid polarimetry SAR data

    NASA Astrophysics Data System (ADS)

    Suneela Mishra, J. V. D.; Misra, Tapan

    2016-05-01

    This paper presents an overview of the estimation of noise, techniques for noise removal in Single Look Complex (SLC) as well as hybrid polarimetry decomposed images and the effects of noise removal in SAR images, using RISAT-1 data. Thermal noise affects the signal to noise ratio as well as radiometry of the SAR images. Different approaches adopted for estimating the thermal noise using onboard noise measurements and from the noise equivalent area of the images like calm reservoirs, lakes, etc., for RISAT-1 SAR are discussed. Subsequent to noise removal, its effect on minimum detectable noise and SNR of the images is addressed. Traditional noise removal methods affect the phase of the data, which in turn affect advanced SAR applications. A brief overview of the hybrid polarimetry configuration of RISAT-1 SAR, one of the emerging trends in polarimetry domain, is given and the effect of using noise removed single look complex (SLC) images for polarimetry decomposition is brought out. Thereby, a new technique for thermal noise removal in polarimetry decomposed data is presented.

  20. TerraSAR-X mission

    NASA Astrophysics Data System (ADS)

    Werninghaus, Rolf

    2004-01-01

    The TerraSAR-X is a German national SAR- satellite system for scientific and commercial applications. It is the continuation of the scientifically and technologically successful radar missions X-SAR (1994) and SRTM (2000) and will bring the national technology developments DESA and TOPAS into operational use. The space segment of TerraSAR-X is an advanced high-resolution X-Band radar satellite. The system design is based on a sound market analysis performed by Infoterra. The TerraSAR-X features an advanced high-resolution X-Band Synthetic Aperture Radar based on the active phased array technology which allows the operation in Spotlight-, Stripmap- and ScanSAR Mode with various polarizations. It combines the ability to acquire high resolution images for detailed analysis as well as wide swath images for overview applications. In addition, experimental modes like the Dual Receive Antenna Mode allow for full-polarimetric imaging as well as along track interferometry, i.e. moving target identification. The Ground Segment is optimized for flexible response to (scientific and commercial) User requests and fast image product turn-around times. The TerraSAR-X mission will serve two main goals. The first goal is to provide the strongly supportive scientific community with multi-mode X-Band SAR data. The broad spectrum of scientific application areas include Hydrology, Geology, Climatology, Oceanography, Environmental Monitoring and Disaster Monitoring as well as Cartography (DEM Generation) and Interferometry. The second goal is the establishment of a commercial EO-market in Europe which is driven by Infoterra. The commercial goal is the development of a sustainable EO-business so that the e.g. follow-on systems can be completely financed by industry from the profit. Due to its commercial potential, the TerraSAR-X project will be implemented based on a public-private partnership with the Astrium GmbH. This paper will describe first the mission objectives as well as the

  1. Crystal structure of the SarS protein from Staphylococcus aureus.

    PubMed

    Li, Ronggui; Manna, Adhar C; Dai, Shaodong; Cheung, Ambrose L; Zhang, Gongyi

    2003-07-01

    The expression of virulence determinants in Staphylococcus aureus is controlled by global regulatory loci (e.g., sarA and agr). One of these determinants, protein A (spa), is activated by sarS, which encodes a 250-residue DNA-binding protein. Genetic analysis indicated that the agr locus likely mediates spa repression by suppressing the transcription of sarS. Contrary to SarA and SarR, which require homodimer formation for proper function, SarS is unusual within the SarA protein family in that it contains two homologous halves, with each half sharing sequence similarity to SarA and SarR. Here we report the 2.2 A resolution X-ray crystal structure of the SarS protein. SarS has folds similar to those of SarR and, quite plausibly, the native SarA structure. Two typical winged-helix DNA-binding domains are connected by a well-ordered loop. The interactions between the two domains are extensive and conserved. The putative DNA-binding surface is highly positively charged. In contrast, negatively charged patches are located opposite to the DNA-binding surface. Furthermore, sequence alignment and structural comparison revealed that MarR has folds similar to those of SarR and SarS. Members of the MarR protein family have previously been implicated in the negative regulation of an efflux pump involved in multiple antibiotic resistance in many gram-negative species. We propose that MarR also belongs to the winged-helix protein family and has a similar mode of DNA binding as SarR and SarS and possibly the entire SarA protein family member. Based on the structural differences of SarR, SarS, and MarR, we further classified these winged-helix proteins to three subfamilies, SarA, SarS, and MarR. Finally, a possible transcription regulation mechanism is proposed.

  2. Interferometric SAR to EO image registration problem

    NASA Astrophysics Data System (ADS)

    Rogers, George W.; Mansfield, Arthur W.; Rais, Houra

    2000-08-01

    Historically, SAR to EO registration accuracy has been at the multiple pixel level compared to sub-pixel EO to EO registration accuracies. This is due to a variety of factors including the different scattering characteristics of the ground for EO and SAR, SAR speckle, and terrain induced geometric distortion. One approach to improving the SAR to EO registration accuracy is to utilize the full information from multiple SAR surveys using interferometric techniques. In this paper we will examine this problem in detail with an example using ERS SAR imagery. Estimates of the resulting accuracy based on ERS are included.

  3. A TACSAT SAR concept

    NASA Astrophysics Data System (ADS)

    Hall, C. D.; Baker, C. J.; Keyte, G. E.; Murphy, L. M.

    1993-02-01

    The payload concept covered is that of a low cost, high performance radar sensor capable of detecting and recognizing static objects within an imaged scene of the Earth's surface using the Synthetic Aperture Radar (SAR) technique. The overall system is integrated with a TACSAT platform in Low Earth Orbit (LEO) and, although only passing reference is made to this feature, the radar could also have a capability for the detection of Ground Moving Targets (GMTI). A parametric review of such a sensor in the light of the target and background features to be observed is provided. A design concept is included showing the possible hardware realization of a candidate system, as well as budgets for the mass, size, power, and pointing requirements of the instrument. Additional design features considered are the influence that short duration missions may have on hardware redundancy and the effect of short, low duty-cycle observation periods on solar array and battery sizing. The way towards a low cost R and D demonstrator system allowing a practical investigation of the key techniques and technologies is addressed.

  4. Research on Multi-Temporal PolInSAR Modeling and Applications

    NASA Astrophysics Data System (ADS)

    Hong, Wen; Pottier, Eric; Chen, Erxue

    2014-11-01

    In the study of theory and processing methodology, we apply accurate topographic phase to the Freeman-Durden decomposition for PolInSAR data. On the other hand, we present a TomoSAR imaging method based on convex optimization regularization theory. The target decomposition and reconstruction performance will be evaluated by multi-temporal Land P-band fully polarimetric images acquired in BioSAR campaigns. In the study of hybrid Quad-Pol system performance, we analyse the expression of range ambiguity to signal ratio (RASR) in this architecture. Simulations are used to testify its advantage in the improvement of range ambiguities.

  5. Optical and SAR data integration for automatic change pattern detection

    NASA Astrophysics Data System (ADS)

    Mishra, B.; Susaki, J.

    2014-09-01

    Automatic change pattern mapping in urban and sub-urban area is important but challenging due to the diversity of urban land use pattern. With multi-sensor imagery, it is possible to generate multidimensional unique information of Earth surface features that allow developing a relationship between a response of each feature to synthetic aperture radar (SAR) and optical sensors to track the change automatically. Thus, a SAR and optical data integration framework for change detection and a relationship for automatic change pattern detection were developed. It was carried out in three steps: (i) Computation of indicators from SAR and optical images, namely: normalized difference ratio (NDR) from multi-temporal SAR images and the normalized difference vegetation index difference (NDVI) from multi-temporal optical images, (ii) computing the change magnitude image from NDR and ΔNDVI and delineating the change area and (iii) the development of an empirical relationship, for automatic change pattern detection. The experiment was carried out in an outskirts part of Ho Chi Minh City, one of the fastest growing cities in the world. The empirical relationship between the response of surface feature to optical and SAR imagery has successfully delineated six changed classes in a very complex urban sprawl area that was otherwise impossible with multi-spectral imagery. The improvement of the change detection results by making use of the unique information on both sensors, optical and SAR, is also noticeable with a visual inspection and the kappa index was increased by 0.13 (0.75 to 0.88) in comparison to only optical images.

  6. SARS Patients and Their Close Contacts

    MedlinePlus

    ... Fact Sheet for SARS Patients and Their Close Contacts Format: Select one PDF [256 KB] Recommend on ... that are not now known. What does "close contact" mean? In the context of SARS, close contact ...

  7. P-3 SAR motion compensation techniques

    NASA Astrophysics Data System (ADS)

    Schwartz, Debra S.; Mansfield, Arthur W.; Roth, Duane; Rais, Houra

    2000-08-01

    The potential of airborne SAR to support the search and rescue mission needs to be investigated. Interferometric SAR (IFSAR) is to process P-3 airborne SAR data to evaluate products such as Coherent Change Detection (CCD) and Digital Elevation Models (DEM). The most crucial step in this process is the precise registration of the two SAR images obtained from separate passes. This paper presents a new technique for this registration step.

  8. Method for removing RFI from SAR images

    DOEpatents

    Doerry, Armin W.

    2003-08-19

    A method of removing RFI from a SAR by comparing two SAR images on a pixel by pixel basis and selecting the pixel with the lower magnitude to form a composite image. One SAR image is the conventional image produced by the SAR. The other image is created from phase-history data which has been filtered to have the frequency bands containing the RFI removed.

  9. A dense medium electromagnetic scattering model for the InSAR correlation of snow

    NASA Astrophysics Data System (ADS)

    Lei, Yang; Siqueira, Paul; Treuhaft, Robert

    2016-05-01

    Snow characteristics, such as snow water equivalent (SWE) and snow grain size, are important characteristics for the monitoring of the global hydrological cycle and as indicators of climate change. This paper derives an interferometric synthetic aperture radar (InSAR) scattering model for dense media, such as snow, which takes into account multiple scattering effects through the Quasi-Crystalline Approximation. The result of this derivation is a simplified version of the InSAR correlation model derived for relating the InSAR correlation measurements to the snowpack characteristics of grain size, volume fraction, and layer depth as well as those aspects of the volume-ground interaction that affects the interferometric observation (i.e., the surface topography and the ratio of ground-to-volume scattering). Based on the model, the sensitivity of the InSAR correlation measurements to the snow characteristics is explored by simulation. Through this process, it is shown that Ka-band InSAR phase has a good sensitivity to snow grain size and volume fraction, while for lower frequency signals (Ku-band to L-band), the InSAR correlation magnitude and phase have a sensitivity to snow depth. Since the formulation depends, in part, on the pair distribution function, three functional forms of the pair distribution function are implemented and their effects on InSAR phase measurements compared. The InSAR scattering model described in this paper is intended to be an observational prototype for future Ka-band and L-band InSAR missions, such as NASA's Surface Water and Ocean Topography and NASA-ISRO Synthetic Aperture Radar missions, planned for launch in the 2020-2021 time frame. This formulation also enables further investigation of the InSAR-based snow retrieval approaches.

  10. Kronecker STAP and SAR GMTI

    NASA Astrophysics Data System (ADS)

    Greenewald, Kristjan H.; Zelnio, Edmund G.; Hero, Alfred O.

    2016-05-01

    As a high resolution radar imaging modality, SAR detects and localizes non-moving targets accurately, giving it an advantage over lower resolution GMTI radars. Moving target detection is more challenging due to target smearing and masking by clutter. Space-time adaptive processing (STAP) is often used on multiantenna SAR to remove the stationary clutter and enhance the moving targets. In (Greenewald et al., 2016),1 it was shown that the performance of STAP can be improved by modeling the clutter covariance as a space vs. time Kronecker product with low rank factors, providing robustness and reducing the number of training samples required. In this work, we present a massively parallel algorithm for implementing Kronecker product STAP, enabling application to very large SAR datasets (such as the 2006 Gotcha data collection) using GPUs. Finally, we develop an extension of Kronecker STAP that uses information from multiple passes to improve moving target detection.

  11. Monsoon '90 - Preliminary SAR results

    NASA Technical Reports Server (NTRS)

    Dubois, Pascale C.; Van Zyl, Jakob J.; Guerra, Abel G.

    1992-01-01

    Multifrequency polarimetric synthetic aperture radar (SAR) images of the Walnut Gulch watershed near Tombstone, Arizona were acquired on 28 Mar. 1990 and on 1 Aug. 1990. Trihedral corner reflectors were deployed prior to both overflights to allow calibration of the two SAR data sets. During both overflights, gravimetric soil moisture and dielectric constant measurements were made. Detailed vegetation height, density, and water content measurements were made as part of the Monsoon 1990 Experiment. Preliminary results based on analysis of the multitemporal polarimetric SAR data are presented. Only the C-band data (5.7-cm wavelength) radar images show significant difference between Mar. and Aug., with the strongest difference observed in the HV images. Based on the radar data analysis and the in situ measurements, we conclude that these differences are mainly due to changes in the vegetation and not due to the soil moisture changes.

  12. Monsoon 1990: Preliminary SAR results

    NASA Technical Reports Server (NTRS)

    Vanzyl, Jakob J.; Dubois, Pascale; Guerra, Abel

    1991-01-01

    Multifrequency polarimetric synthetic aperture radar (SAR) images of the Walnut Gulch watershed near Tombstone, Arizona were acquired on 28 Mar. 1990 and on 1 Aug. 1990. Trihedral corner reflectors were deployed prior to both overflights to allow calibration of the two SAR data sets. During both overflights, gravimetric soil moisture and dielectric constant measurements were made. Detailed vegetation height, density, and water content measurements were made as part of the Monsoon 1990 Experiment. Preliminary results based on analysis of the multitemporal polarimetric SAR data are presented. Only the C-band data (5.7-cm wavelength) radar images show significant difference between Mar. and Aug., with the strongest difference observed in the HV images. Based on the radar data analysis and the in situ measurements, we conclude that these differences are mainly due to changes in the vegetation and not due to the soil moisture changes.

  13. Registration of interferometric SAR images

    NASA Technical Reports Server (NTRS)

    Lin, Qian; Vesecky, John F.; Zebker, Howard A.

    1992-01-01

    Interferometric synthetic aperture radar (INSAR) is a new way of performing topography mapping. Among the factors critical to mapping accuracy is the registration of the complex SAR images from repeated orbits. A new algorithm for registering interferometric SAR images is presented. A new figure of merit, the average fluctuation function of the phase difference image, is proposed to evaluate the fringe pattern quality. The process of adjusting the registration parameters according to the fringe pattern quality is optimized through a downhill simplex minimization algorithm. The results of applying the proposed algorithm to register two pairs of Seasat SAR images with a short baseline (75 m) and a long baseline (500 m) are shown. It is found that the average fluctuation function is a very stable measure of fringe pattern quality allowing very accurate registration.

  14. SARS: hospital infection control and admission strategies.

    PubMed

    Ho, Pak-Leung; Tang, Xiao-Ping; Seto, Wing-Hong

    2003-11-01

    Nosocomial clustering with transmission to health care workers, patients and visitors is a prominent feature of severe acute respiratory syndrome (SARS). Hospital outbreaks of SARS typically occurred within the first week after admission of the very first SARS cases when the disease was not recognized and before isolation measures were implemented. In the majority of nosocomial infections, there was a history of close contact with a SARS patient, and transmission occurred via large droplets, direct contact with infectious material or by contact with fomites contaminated by infectious material. In a few instances, potential airborne transmission was reported in association with endotracheal intubation, nebulised medications and non-invasive positive pressure ventilation of SARS patients. In all SARS-affected countries, nosocomial transmission of the disease was effectively halted by enforcement of routine standard, contact and droplet precautions in all clinical areas and additional airborne precautions in the high-risk areas. In Hong Kong, where there are few private rooms for patient isolation, some hospitals have obtained good outcome by having designated SARS teams and separate wards for patient triage, confirmed SARS cases and step-down of patients in whom SARS had been ruled out. In conclusion, SARS represents one of the new challenges for those who are involved in hospital infection control. As SARS might re-emerge, all hospitals should take advantage of the current SARS-free interval to review their infection control programmes, alert mechanisms, response capability and to repair any identified inadequacies.

  15. Foliage problem in interferometric SAR

    NASA Astrophysics Data System (ADS)

    Rogers, George W.; Mansfield, Arthur W.; Roth, Duane; Poehler, Paul L.; Rais, Houra

    1999-08-01

    Interferometric SAR exploits the coherent nature of multiple synthetic aperture radar images to recover phase (range difference) information and thence terrain evaluation data as well as other phase derivative products such as Coherent Change Detection (CCD). Of the numerous factors that can degrade the coherency of multiple SAR collections, foliage constitutes one of the most challenging. The foliage problem in IFSAR is discussed and an airborne multiple pass collection is used to illustrate some facets of the problem. Resolution as a variable in the tradeoff between the bias and variance of the interferogram is discussed in the context of the example.

  16. sarU, a sarA homolog, is repressed by SarT and regulates virulence genes in Staphylococcus aureus.

    PubMed

    Manna, Adhar C; Cheung, Ambrose L

    2003-01-01

    In searching the Staphylococcus aureus genome, we previously identified sarT, a homolog of sarA, which encodes a repressor for alpha-hemolysin synthesis. Adjacent but transcribed divergently to sarT is sarU, which encodes a 247-residue polypeptide, almost twice the length of SarA. Sequence alignment disclosed that SarU, like SarS, which is another SarA homolog, could be envisioned as a molecule with two halves, with each half being homologous to SarA. SarU, as a member of the SarA family proteins, disclosed conservation of basic residues within the helix-turn-helix motif and within the beta hairpin loop, two putative DNA binding domains within this protein family. The transcription of sarU is increased in a sarT mutant. Gel shift and transcriptional fusion studies revealed that SarT can bind to the sarU promoter region, probably acting as a repressor for sarU transcription. The expression of RNAII and RNAIII of agr is decreased in a sarU mutant. As RNAIII expression is up-regulated in a sarT mutant, we hypothesize that sarT may down regulate agr RNAIII expression by repressing sarU, a positive activator of agr expression. We propose that, in addition to the quorum sensing effect of the autoinducing peptide of agr, the sarT-sarU pathway may represent a secondary amplification loop whereby the expression of agr (e.g., those found in vivo) might repress sarT, leading to increased expression of sarU. Elevated sarU expression would result in additional amplification of the original agr signal.

  17. SARS: a health system's perspective.

    PubMed

    Beard, Leslie; Clark, Caroline

    2003-01-01

    Effective communications with different stakeholders was critical for health systems everywhere during the worldwide SARS outbreak earlier this year. For Capital Health in Edmonton, Alberta, the health system was able to build on its past experiences in dealing with meningococcal outbreaks and its planning for a pandemic flu. PMID:14628532

  18. Further SEASAT SAR coastal ocean wave analysis

    NASA Technical Reports Server (NTRS)

    Kasischke, E. S.; Shuchman, R. A.; Meadows, G. A.; Jackson, P. L.; Tseng, Y.

    1981-01-01

    Analysis techniques used to exploit SEASAT synthetic aperture radar (SAR) data of gravity waves are discussed and the SEASAT SAR's ability to monitor large scale variations in gravity wave fields in both deep and shallow water is evaluated. The SAR analysis techniques investigated included motion compensation adjustments and the semicausal model for spectral analysis of SAR wave data. It was determined that spectra generated from fast Fourier transform analysis (FFT) of SAR wave data were not significantly altered when either range telerotation adjustments or azimuth focus shifts were used during processing of the SAR signal histories, indicating that SEASAT imagery of gravity waves is not significantly improved or degraded by motion compensation adjustments. Evaluation of the semicausal (SC) model using SEASAT SAR data from Rev. 974 indicates that the SC spectral estimates were not significantly better than the FFT results.

  19. Late-summer sea ice segmentation with multi-polarisation SAR features in C and X band

    NASA Astrophysics Data System (ADS)

    Fors, Ane S.; Brekke, Camilla; Doulgeris, Anthony P.; Eltoft, Torbjørn; Renner, Angelika H. H.; Gerland, Sebastian

    2016-02-01

    In this study, we investigate the potential of sea ice segmentation by C- and X-band multi-polarisation synthetic aperture radar (SAR) features during late summer. Five high-resolution satellite SAR scenes were recorded in the Fram Strait covering iceberg-fast first-year and old sea ice during a week with air temperatures varying around 0 °C. Sea ice thickness, surface roughness and aerial photographs were collected during a helicopter flight at the site. Six polarimetric SAR features were extracted for each of the scenes. The ability of the individual SAR features to discriminate between sea ice types and their temporal consistency were examined. All SAR features were found to add value to sea ice type discrimination. Relative kurtosis, geometric brightness, cross-polarisation ratio and co-polarisation correlation angle were found to be temporally consistent in the investigated period, while co-polarisation ratio and co-polarisation correlation magnitude were found to be temporally inconsistent. An automatic feature-based segmentation algorithm was tested both for a full SAR feature set and for a reduced SAR feature set limited to temporally consistent features. In C band, the algorithm produced a good late-summer sea ice segmentation, separating the scenes into segments that could be associated with different sea ice types in the next step. The X-band performance was slightly poorer. Excluding temporally inconsistent SAR features improved the segmentation in one of the X-band scenes.

  20. Electrical swing adsorption gas storage and delivery system

    DOEpatents

    Judkins, Roddie R.; Burchell, Timothy D.

    1999-01-01

    Systems and methods for electrical swing natural gas adsorption are described. An apparatus includes a pressure vessel; an electrically conductive gas adsorptive material located within the pressure vessel; and an electric power supply electrically connected to said adsorptive material. The adsorptive material can be a carbon fiber composite molecular sieve (CFCMS). The systems and methods provide advantages in that both a high energy density and a high ratio of delivered to stored gas are provided.

  1. Electrical swing adsorption gas storage and delivery system

    DOEpatents

    Judkins, R.R.; Burchell, T.D.

    1999-06-15

    Systems and methods for electrical swing natural gas adsorption are described. An apparatus includes a pressure vessel; an electrically conductive gas adsorptive material located within the pressure vessel; and an electric power supply electrically connected to said adsorptive material. The adsorptive material can be a carbon fiber composite molecular sieve (CFCMS). The systems and methods provide advantages in that both a high energy density and a high ratio of delivered to stored gas are provided. 5 figs.

  2. Modeling the adsorption of mixed gases based on pure gas adsorption properties

    NASA Astrophysics Data System (ADS)

    Tzabar, N.; Holland, H. J.; Vermeer, C. H.; ter Brake, H. J. M.

    2015-12-01

    Sorption-based Joule-Thomson (JT) cryocoolers usually operate with pure gases. A sorption-based compressor has many benefits; however, it is limited by the pressure ratios it can provide. Using a mixed-refrigerant (MR) instead of a pure refrigerant in JT cryocoolers allows working at much lower pressure ratios. Therefore, it is attractive using MRs in sorption- based cryocoolers in order to reduce one of its main limitations. The adsorption of mixed gases is usually investigated under steady-state conditions, mainly for storage and separation processes. However, the process in a sorption compressor goes through various temperatures, pressures and adsorption concentrations; therefore, it differs from the common mixed gases adsorption applications. In order to simulate the sorption process in a compressor a numerical analysis for mixed gases is developed, based on pure gas adsorption characteristics. The pure gas adsorption properties have been measured for four gases (nitrogen, methane, ethane, and propane) with Norit-RB2 activated carbon. A single adsorption model is desired to describe the adsorption of all four gases. This model is further developed to a mixed-gas adsorption model. In future work more adsorbents will be tested using these four gases and the adsorption model will be verified against experimental results of mixed-gas adsorption measurements.

  3. Application of pixel segmentation to the low rate compression of complex SAR imagery

    SciTech Connect

    Ives, R.W.; Eichel, P.; Magotra, N.

    1998-03-01

    This paper describes a technique to identify pixels within a subregion (chip) of a complex or detected SAR image which are to be losslessly compressed while the remainder of the image is subjected to a high compression ratio. This multi-modal compression is required for the intelligent low rate compression of SAR imagery, which addresses the problem of transmitting massive amounts of high resolution complex SAR data from a remote airborne sensor to a ground station for exploitation by an automatic target recognition (ATR) system, in a real time environment, over a narrow bandwidth. The ATR system results might then be presented to an image analyst who, using the contextual information from the SAR image, makes final target determination.

  4. Characterization of spatial statistics of distributed targets in SAR data. [applied to sea-ice data

    NASA Technical Reports Server (NTRS)

    Rignot, E.; Kwok, R.

    1993-01-01

    A statistical approach to the analysis of spatial statistics in polarimetric multifrequency SAR data, which is aimed at extracting the intrinsic variability of the target by removing variability from other sources, is presented. An image model, which takes into account three sources of spatial variability, namely, image speckle, system noise, and the intrinsic spatial variability of the target or texture, is described. It is shown that the presence of texture increases the image variance-to-mean square ratio and introduces deviations of the image autocovariance function from the expected SAR system response. The approach is exemplified by sea-ice SAR imagery acquired by the Jet Propulsion Laboratory three-frequency polarimetric airborne SAR. Data obtained indicate that, for different sea-ice types, the spatial statistics seem to vary more across frequency than across polarization and the observed differences increase in magnitude with decreasing frequency.

  5. Controlling Data Collection to Support SAR Image Rotation

    DOEpatents

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

    2008-10-14

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

  6. Applying PolSAR and PolInSAR to Forest Structure Information Extraction

    NASA Astrophysics Data System (ADS)

    Chen, E.; Li, Z.; Li, W.; Feng, Q.; Zhou, W.; Pottier, E.; Hong, W.

    2013-01-01

    The key research activities and achievements in the field of applying PolSAR and PolInSAR to forest structure information extraction in DRAGON 2 are summarized in this paper. The limitation of the ALOS PolInSAR dataset acquired in the Culai test site for forest height extraction because of its long temporal baseline (46 days), and how the PolInSAR coherence optimization methods can help improve the topography inversion accuracy under forest canopy were presented. We have analyzed and evaluated the capability of multiple polarization parameters extracted from different frequency PolSAR data for forest scar mapping in the Shibazhan test site, and developed the land cover classification method based on SVM (Support Vector Machine) using PolSAR data. With the L-band E-SAR PolInSAR data acquired in the test site in Germany, we developed forest above ground biomass (AGB) estimation approach based on polarization coherence tomography (PCT).

  7. 5. SWITCH TOWER AND JUNCTION OF S.A.R. #1 & S.A.R. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. SWITCH TOWER AND JUNCTION OF S.A.R. #1 & S.A.R. #2 TRANSMISSION LINES, MARCH 7, 1916. SCE drawing no. 4932. - Santa Ana River Hydroelectric System, Transmission Lines, Redlands, San Bernardino County, CA

  8. Advanced digital SAR processing study

    NASA Technical Reports Server (NTRS)

    Martinson, L. W.; Gaffney, B. P.; Liu, B.; Perry, R. P.; Ruvin, A.

    1982-01-01

    A highly programmable, land based, real time synthetic aperture radar (SAR) processor requiring a processed pixel rate of 2.75 MHz or more in a four look system was designed. Variations in range and azimuth compression, number of looks, range swath, range migration and SR mode were specified. Alternative range and azimuth processing algorithms were examined in conjunction with projected integrated circuit, digital architecture, and software technologies. The advaced digital SAR processor (ADSP) employs an FFT convolver algorithm for both range and azimuth processing in a parallel architecture configuration. Algorithm performace comparisons, design system design, implementation tradeoffs and the results of a supporting survey of integrated circuit and digital architecture technologies are reported. Cost tradeoffs and projections with alternate implementation plans are presented.

  9. Parallel strategies for SAR processing

    NASA Astrophysics Data System (ADS)

    Segoviano, Jesus A.

    2004-12-01

    This article proposes a series of strategies for improving the computer process of the Synthetic Aperture Radar (SAR) signal treatment, following the three usual lines of action to speed up the execution of any computer program. On the one hand, it is studied the optimization of both, the data structures and the application architecture used on it. On the other hand it is considered a hardware improvement. For the former, they are studied both, the usually employed SAR process data structures, proposing the use of parallel ones and the way the parallelization of the algorithms employed on the process is implemented. Besides, the parallel application architecture classifies processes between fine/coarse grain. These are assigned to individual processors or separated in a division among processors, all of them in their corresponding architectures. For the latter, it is studied the hardware employed on the computer parallel process used in the SAR handling. The improvement here refers to several kinds of platforms in which the SAR process is implemented, shared memory multicomputers, and distributed memory multiprocessors. A comparison between them gives us some guidelines to follow in order to get a maximum throughput with a minimum latency and a maximum effectiveness with a minimum cost, all together with a limited complexness. It is concluded and described, that the approach consisting of the processing of the algorithms in a GNU/Linux environment, together with a Beowulf cluster platform offers, under certain conditions, the best compromise between performance and cost, and promises the major development in the future for the Synthetic Aperture Radar computer power thirsty applications in the next years.

  10. Reflectors for SAR performance testing.

    SciTech Connect

    Doerry, Armin Walter

    2008-01-01

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

  11. Representing SAR complex image pixels

    NASA Astrophysics Data System (ADS)

    Doerry, A. W.

    2016-05-01

    Synthetic Aperture Radar (SAR) images are often complex-valued to facilitate specific exploitation modes. Furthermore, these pixel values are typically represented with either real/imaginary (also known as I/Q) values, or as Magnitude/Phase values, with constituent components comprised of integers with limited number of bits. For clutter energy well below full-scale, Magnitude/Phase offers lower quantization noise than I/Q representation. Further improvement can be had with companding of the Magnitude value.

  12. SAR Image Complex Pixel Representations

    SciTech Connect

    Doerry, Armin W.

    2015-03-01

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

  13. Bats, civets and the emergence of SARS.

    PubMed

    Wang, L F; Eaton, B T

    2007-01-01

    Severe acute respiratory syndrome (SARS) was the first pandemic transmissible disease of previously unknown aetiology in the twenty-first century. Early epidemiologic investigations suggested an animal origin for SARS-CoV. Virological and serological studies indicated that masked palm civets ( Paguma larvata), together with two other wildlife animals, sampled from a live animal market were infected with SARS-CoV or a closely related virus. Recently, horseshoe bats in the genus Rhinolophus have been identified as natural reservoir of SARS-like coronaviruses. Here, we review studies by different groups demonstrating that SARS-CoV succeeded in spillover from a wildlife reservoir (probably bats) to human population via an intermediate host(s) and that rapid virus evolution played a key role in the adaptation of SARS-CoVs in at least two nonreservoir species within a short period.

  14. InSAR Forensics: Tracing InSAR Scatterers in High Resolution Optical Image

    NASA Astrophysics Data System (ADS)

    Wang, Yuanyuan; Zhu, XiaoXiang

    2015-05-01

    This paper presents a step towards a better interpretation of the scattering mechanism of different objects and their deformation histories in SAR interferometry (InSAR). The proposed technique traces individual SAR scatterer in high resolution optical images where their geometries, materials, and other properties can be better analyzed and classified. And hence scatterers of a same object can be analyzed in group, which brings us to a new level of InSAR deformation monitoring.

  15. Microstrip antennas for SAR applications

    NASA Technical Reports Server (NTRS)

    Haddad, H. A.

    1983-01-01

    Current and future microstrip antenna technology development for Spaceborne Synthetic Aperture Radars (SAR) are summarized. Some of the electrical and mechanical characteristics of previously and presently developed microstrip SAR antennas are shown. The SEASAT, the SIR-A and presently the SIR-B antennas are all designed for operation at L-band with approximately 22 MHz of bandwidth. The antennas have linear polarization with minimum of 20 dB of polarization purity. Both the SEASAT and SIR-A antennas were designed for a fixed pointing angle of 20.5 deg and 47 deg, respectively. However, the SIR-B has the added feature of mechanical beam steering in elevation (range). With the exception of different mechanical characteristics, it is concluded that present spaceborne SAR antennas have only single frequency and single polarization performance. The lack of large spaceborne antennas operating at the higher degree of fabrication tolerance required for a given performance; and larger feed and radiating element losses.

  16. Building detection in SAR imagery

    SciTech Connect

    Steinbach, Ryan Matthew

    2015-04-01

    Current techniques for building detection in Synthetic Aperture Radar (SAR) imagery can be computationally expensive and/or enforce stringent requirements for data acquisition. I present two techniques that are effective and efficient at determining an approximate building location. This approximate location can be used to extract a portion of the SAR image to then perform a more robust detection. The proposed techniques assume that for the desired image, bright lines and shadows, SAR artifact effects, are approximately labeled. These labels are enhanced and utilized to locate buildings, only if the related bright lines and shadows can be grouped. In order to find which of the bright lines and shadows are related, all of the bright lines are connected to all of the shadows. This allows the problem to be solved from a connected graph viewpoint, where the nodes are the bright lines and shadows and the arcs are the connections between bright lines and shadows. For the first technique, constraints based on angle of depression and the relationship between connected bright lines and shadows are applied to remove unrelated arcs. The second technique calculates weights for the connections and then performs a series of increasingly relaxed hard and soft thresholds. This results in groups of various levels on their validity. Once the related bright lines and shadows are grouped, their locations are combined to provide an approximate building location. Experimental results demonstrate the outcome of the two techniques. The two techniques are compared and discussed.

  17. Intelligent low rate compression of speckled SAR imagery

    SciTech Connect

    Ives, R.W.; Eichel, P.; Magotra, N.

    1997-05-01

    This paper describes a compression technique under development at Sandia National Laboratories for the compression of complex synthetic aperture radar (SAR) imagery at very low overall bit rates. The methods involved combine several elements of existing and new lossy and lossless compression schemes in order to achieve an overall compression ratio of large SAR scenes of at least 50:1, while maintaining reasonable image quality. It is assumed that the end user will be primarily interested in specific regions of interest within the image (called chips), but that the context in which these chips appear within the entire scene is also of importance to an image analyst. The term intelligent is used to signify an external cuer which locates the chips of interest.

  18. Chirp Scaling Algorithms for SAR Processing

    NASA Technical Reports Server (NTRS)

    Jin, M.; Cheng, T.; Chen, M.

    1993-01-01

    The chirp scaling SAR processing algorithm is both accurate and efficient. Successful implementation requires proper selection of the interval of output samples, which is a function of the chirp interval, signal sampling rate, and signal bandwidth. Analysis indicates that for both airborne and spaceborne SAR applications in the slant range domain a linear chirp scaling is sufficient. To perform nonlinear interpolation process such as to output ground range SAR images, one can use a nonlinear chirp scaling interpolator presented in this paper.

  19. A Modular and Configurable Instrument Electronics Architecture for "MiniSAR"- An Advanced Smallsat SAR Instrument

    NASA Astrophysics Data System (ADS)

    Gomez, Jaime; Pastena, Max; Bierens, Laurens

    2013-08-01

    MiniSAR is a Dutch program focused on the development of a commercial smallsat featuring a SAR instrument, led by SSBV as prime contractor. In this paper an Instrument Electronics (IEL) system concept to meet the MiniSAR demands is presented. This system has several specificities wrt similar initiatives in the European space industry, driven by our main requirement: keep it small.

  20. Multibaseline POLInSAR Module for SAR Data Processing and Analysis in RAT (Radar Tools)

    NASA Astrophysics Data System (ADS)

    Neumann, M.; Reiber, A.; Jäger, M.; Guillaso, S.; Hellwich, O.

    2007-03-01

    The combination of SAR Polarimetry (POL- SAR) and SAR Interferometry (InSAR) into Polarimetric SAR Interferometry (POLInSAR) has shown great potential for information extraction from SAR data. Applications have been developed and validated theoretically for POLInSAR data. But due to different reasons these methods are difficult to apply on real data. The SAR observables have to be increased, and the utilization of multiple baselines (MB) is one of the possibilities. There will be a need for data processing and analysis methods and tools to work effectively with multibaseline datasets. In this paper we present the newly developed module for the software package RAT (Radar Tools), which provides these abilities for multibaseline polarimetric interferometric SAR data. It is the first available package of tools for working with MBSAR data. RAT (RAdar Tools [1], [2]) is a collection of tools for advanced image processing of SAR remote sensing data, originally started as a student's project and currently under further development at the Department of Computer Vision and Remote Sensing of the Technical University of Berlin. It is programmed in IDL (Interactive Data Language) and uses IDL widgets as graphical user interface. The purpose of this paper is also to give an overview of the current development status of RAT through addressing the newest structural improvements in RAT as well as recently implemented methods for SAR polarimetry and interferometry.

  1. High resolution SAR applications and instrument design

    NASA Technical Reports Server (NTRS)

    Dionisio, C.; Torre, A.

    1993-01-01

    The Synthetic Aperture Radar (SAR) has viewed, in the last two years, a huge increment of interest from many preset and potential users. The good spatial resolution associated to the all weather capability lead to considering SAR not only a scientific instrument but a tool for verifying and controlling the daily human relationships with the Earth Environment. New missions were identified for SAR as spatial resolution became lower than three meters: disasters, pollution, ships traffic, volcanic eruptions, earthquake effect are only a few of the possible objects which can be effectively detected, controlled and monitored by SAR mounted on satellites. High resolution radar design constraints and dimensioning are discussed.

  2. Bistatic SAR: Signal Processing and Image Formation.

    SciTech Connect

    Wahl, Daniel E.; Yocky, David A.

    2014-10-01

    This report describes the significant processing steps that were used to take the raw recorded digitized signals from the bistatic synthetic aperture RADAR (SAR) hardware built for the NCNS Bistatic SAR project to a final bistatic SAR image. In general, the process steps herein are applicable to bistatic SAR signals that include the direct-path signal and the reflected signal. The steps include preprocessing steps, data extraction to for a phase history, and finally, image format. Various plots and values will be shown at most steps to illustrate the processing for a bistatic COSMO SkyMed collection gathered on June 10, 2013 on Kirtland Air Force Base, New Mexico.

  3. [SARS-CoV infection and pregnancy].

    PubMed

    Ksiezakowska, Kinga; Laszczyk, Magdalena; Wilczyński, Jan; Nowakowska, Dorota

    2008-01-01

    SARS is a highly contagious infection, caused by new coronavirus SARS-CoV. Immunopathological mechanisms responsible for the reaction to SARS-CoV infection have not yet been fully elucidated. Cytokine profile of SARS patients showed marked elevation of Th1 cytokine, interferon gamma, inflammatory cytokines for at least 2 weeks after the onset of the disease. The clinical manifestation of SARS in patients has been of varied nature. Fever of more then 38 degrees C, lasting more then 24 hours, is the most frequently encountered symptom. Other symptoms are non specific and they may include: sore throat, myalgia and nausea. The results of the radiological investigation may appear normal. Infants born to pregnant women with SARS did not appear to have acquired the infection through vertical transmission. However, direct contact with the maternal body fluid which contained SARS-CoV, has put the infants in great danger of perinatal infection. Ribavirin and corticosteroids are usually suggested for the treatment of SARS. However, the ribavirin therapy increases the risk of teratogenic effects in newborns of pregnant women with SARS. Therefore, the usage of this drug is not recommended during pregnancy and lactation. PMID:18510050

  4. Adsorption of thorium from aqueous solutions by perlite.

    PubMed

    Talip, Z; Eral, M; Hiçsönmez, U

    2009-02-01

    The use of expanded perlite for the adsorption of thorium from aqueous solution by batch technique is presented. The effects of particle size, pH of the solution, initial thorium concentration, shaking time, V/m ratio and temperature were determined. It was found that the adsorption capacity increases by the increase in the pH of the suspensions. The rate of thorium adsorption on expanded perlite was observed to be fast in the first hour of the reaction time. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models and the adsorption experiments conducted at 30 +/- 1 degrees C showed that the adsorption isotherms correlated well with the Langmuir model. From the adsorption data, thermodynamic parameters such as DeltaG(o), DeltaH(o) and DeltaS(o) were calculated as a function of temperature.

  5. InfoTerra/TerraSAR initiative

    NASA Astrophysics Data System (ADS)

    Wahl, Manfred W.

    2004-01-01

    The overarching goal of the InfoTerra/TerraSAR Initiative is to establish a self-sustaining operational/commercial business built on Europe"s know-how and experience in space-borne Synthetic Aperture Radar (SAR) technology, in SAR data processing as well as in SAR applications. InfoTerra stands for a new business concept based on supplying innovative geo-information products and services. TerraSAR is a space and ground system conceived to consist of an initial deployment and operation of 2 Radar satellites (one in X- and one in L-band) flying in a tandem configuration in the same orbit. The design of TerraSAR is driven by the market and is user-oriented. TerraSAR is key to capturing a significant proportion of the existing market and to opening new market opportunities, when it becomes operational. The InfoTerra/TerraSAR Initiative has evolved gradually. It started in 1997 as a joint venture between German (DSS) and British (MMS-UK) space industry, strongly supported by both space agencies, DLR and BNSC. In early 2001, DLR and BNSC submitted to ESA the Formal Programme Proposal for InfoTerra/TerraSAR to become an essential element of ESA"s Earth Watch Programme. In summer 2001, when it became evident that there was not yet sufficient support from the ESA Member States to allow immediate start entering into TerraSAR Phase C/D, it has been decided to implement first a TerraSAR consolidation phase. In early 2002, in order to avoid further delays, a contract was signed between DLR and Astrium GmbH on the development of one component of TerraSAR, the TerraSAR-X, in the frame of a national programme, governed by a Public Private Partnership Agreement. Even if now the different launch dates for TerraSAR-X and TerraSAR-L are narrowing down the window of common data acquisition, it is a reasonable starting point, but it should always be kept in mind that the utmost goal for the longterm is to achieve self sustainability by supplying geo-information products and services

  6. Seasonal dynamics of active SAR11 ecotypes in the oligotrophic Northwest Mediterranean Sea

    PubMed Central

    Salter, Ian; Galand, Pierre E; Fagervold, Sonja K; Lebaron, Philippe; Obernosterer, Ingrid; Oliver, Matthew J; Suzuki, Marcelino T; Tricoire, Cyrielle

    2015-01-01

    A seven-year oceanographic time series in NW Mediterranean surface waters was combined with pyrosequencing of ribosomal RNA (16S rRNA) and ribosomal RNA gene copies (16S rDNA) to examine the environmental controls on SAR11 ecotype dynamics and potential activity. SAR11 diversity exhibited pronounced seasonal cycles remarkably similar to total bacterial diversity. The timing of diversity maxima was similar across narrow and broad phylogenetic clades and strongly associated with deep winter mixing. Diversity minima were associated with periods of stratification that were low in nutrients and phytoplankton biomass and characterised by intense phosphate limitation (turnover time<5 h). We propose a conceptual framework in which physical mixing of the water column periodically resets SAR11 communities to a high diversity state and the seasonal evolution of phosphate limitation competitively excludes deeper-dwelling ecotypes to promote low diversity states dominated (>80%) by SAR11 Ia. A partial least squares (PLS) regression model was developed that could reliably predict sequence abundances of SAR11 ecotypes (Q2=0.70) from measured environmental variables, of which mixed layer depth was quantitatively the most important. Comparison of clade-level SAR11 rRNA:rDNA signals with leucine incorporation enabled us to partially validate the use of these ratios as an in-situ activity measure. However, temporal trends in the activity of SAR11 ecotypes and their relationship to environmental variables were unclear. The strong and predictable temporal patterns observed in SAR11 sequence abundance was not linked to metabolic activity of different ecotypes at the phylogenetic and temporal resolution of our study. PMID:25238399

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

    NASA Astrophysics Data System (ADS)

    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. SAR Altimetry in Coastal Zone: Performances, Limits, Perspectives

    NASA Astrophysics Data System (ADS)

    Dinardo, S.; Benveniste, J.

    2011-12-01

    Up to now, any effort to retrieve the coastal zone phenomena from the space has been hindered by the intrinsic incapacity of conventional radar altimeters to sample all but largest scales involved in the coastal processes due to its insufficient along- track resolution. However, nowadays, a new technology in Space-borne Altimetry has become reality: the Synthetic Aperture Radar (SAR) Altimeter. The acquisition of altimetric data in SAR mode ensures a higher resolving measurement power that shall enable scientists for the first time to aspire to measure even short-scale weak coastal phenomena, thanks to the 20- fold smaller along track radar resolution and 10 dB higher Signal to Noise ratio. The secondary, but significant in coastal zone, effect of the radar footprint shrinking is the expected reduced impact of land contamination on the radar waveforms in the proximity of the shore. As a consequence of this effect, the advent of SAR focusing promises to bring the satellite altimetry remote sensing closer to the shore up to around 500 meters. Anyway, this lower bound of 500 meter on coastal proximity is not always reachable, as the footprint shrinking occurs only in along track direction while the across track resolution shall remain basically unaltered. Hence, the orientation of the satellite ground-track with respect the coastline plays a role crucial for an effective filtering out of the off-nadir land-originated signals. In the present work, utilizing the current CryoSat-2 Altimeter Dataset (SAR L1b) acquired over coastal sea water, and by retracking the SAR L1b waveforms, a performances study of SAR altimetry in coastal zone will be addressed and the benefits and limits of this new technology highlighted. As particular study area, the Tyrrhenian Sea has been selected: statistics and metrics for sea surface height and significant wave height, as calculated from a cycle of passes, will be assessed, shown and interpreted. Finally, employing the Cryo

  9. Sentinel-3 SAR Altimetry Toolbox

    NASA Astrophysics Data System (ADS)

    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

  10. Random sequential adsorption of trimers and hexamers.

    PubMed

    Cieśla, Michał; Barbasz, Jakub

    2013-12-01

    Adsorption of trimers and hexamers built of identical spheres was studied numerically using the random sequential adsorption (RSA) algorithm. Particles were adsorbed on a two-dimensional, flat and homogeneous surface. Numerical simulations allowed us to determine the maximal random coverage ratio, RSA kinetics as well as the available surface function (ASF), which is crucial for determining the kinetics of the adsorption process obtained experimentally. Additionally, the density autocorrelation function was measured. All the results were compared with previous results obtained for spheres, dimers and tetramers.

  11. Cross-calibration between airborne SAR sensors

    NASA Technical Reports Server (NTRS)

    Zink, Manfred; Olivier, Philippe; Freeman, Anthony

    1993-01-01

    As Synthetic Aperture Radar (SAR) system performance and experience in SAR signature evaluation increase, quantitative analysis becomes more and more important. Such analyses require an absolute radiometric calibration of the complete SAR system. To keep the expenditure on calibration of future multichannel and multisensor remote sensing systems (e.g., X-SAR/SIR-C) within a tolerable level, data from different tracks and different sensors (channels) must be cross calibrated. The 1989 joint E-SAR/DC-8 SAR calibration campaign gave a first opportunity for such an experiment, including cross sensor and cross track calibration. A basic requirement for successful cross calibration is the stability of the SAR systems. The calibration parameters derived from different tracks and the polarimetric properties of the uncalibrated data are used to describe this stability. Quality criteria for a successful cross calibration are the agreement of alpha degree values and the consistency of radar cross sections of equally sized corner reflectors. Channel imbalance and cross talk provide additional quality in case of the polarimetric DC-8 SAR.

  12. SAR Speckle Noise Reduction Using Wiener Filter

    NASA Technical Reports Server (NTRS)

    Joo, T. H.; Held, D. N.

    1983-01-01

    Synthetic aperture radar (SAR) images are degraded by speckle. A multiplicative speckle noise model for SAR images is presented. Using this model, a Wiener filter is derived by minimizing the mean-squared error using the known speckle statistics. Implementation of the Wiener filter is discussed and experimental results are presented. Finally, possible improvements to this method are explored.

  13. Coordinated Response to SARS, Vancouver, Canada

    PubMed Central

    Petric, Martin; Daly, Patricia; Parker, Robert A.; Bryce, Elizabeth; Doyle, Patrick W.; Noble, Michael A.; Roscoe, Diane L.; Tomblin, Joan; Yang, Tung C.; Krajden, Mel; Patrick, David M.; Pourbohloul, Babak; Goh, Swee Han; Bowie, William R.; Booth, Tim F.; Tweed, S. Aleina; Perry, Thomas L.; McGeer, Allison; Brunham, Robert C.

    2006-01-01

    Two Canadian urban areas received travelers with severe acute respiratory syndrome (SARS) before the World Health Organization issued its alert. By July 2003, Vancouver had identified 5 cases (4 imported); Toronto reported 247 cases (3 imported) and 43 deaths. Baseline preparedness for pandemic threats may account for the absence of sustained transmission and fewer cases of SARS in Vancouver. PMID:16494736

  14. Regularization Analysis of SAR Superresolution

    SciTech Connect

    DELAURENTIS,JOHN M.; DICKEY,FRED M.

    2002-04-01

    Superresolution concepts offer the potential of resolution beyond the classical limit. This great promise has not generally been realized. In this study we investigate the potential application of superresolution concepts to synthetic aperture radar. The analytical basis for superresolution theory is discussed. In a previous report the application of the concept to synthetic aperture radar was investigated as an operator inversion problem. Generally, the operator inversion problem is ill posed. This work treats the problem from the standpoint of regularization. Both the operator inversion approach and the regularization approach show that the ability to superresolve SAR imagery is severely limited by system noise.

  15. Advanced antennas for SAR spacecraft

    NASA Technical Reports Server (NTRS)

    Gail, William B.

    1993-01-01

    Single and multi-frequency antenna concepts were developed to evaluate the feasibility of building large aperture polarimetric synthetic aperture radar (SAR) systems to be launched in low cost vehicles such as the Delta 2. The antennas are 18.9 m long by 2.6 m wide (L-band) and achieve single polarization imaging to an incidence angle of 55 degrees and dual/quad imaging to 42 degrees. When combined with strawman spacecraft designs, both concepts meet the mass and volume constraints imposed by a Delta 2 launch.

  16. Sidelobe reduction via adaptive FIR filtering in SAR imagery.

    PubMed

    Degraaf, S R

    1994-01-01

    The paper describes a class of adaptive weighting functions that greatly reduce sidelobes, interference, and noise in Fourier transform data. By restricting the class of adaptive weighting functions, the adaptively weighted Fourier transform data can be represented as the convolution of the unweighted Fourier transform with a data adaptive FIR filter where one selects the FIR filter coefficients to maximize signal-to-interference ratio. This adaptive sidelobe reduction (ASR) procedure is analogous to Capon's (1969) minimum variance method (MVM) of adaptive spectral estimation. Unlike MVM, which provides a statistical estimate of the real-valued power spectral density, thereby estimating noise level and improving resolution, ASR provides a single-realization complex-valued estimate of the Fourier transform that suppresses sidelobes and noise. Further, the computational complexity of ASR is dramatically lower than that of MVM, which is critical for large multidimensional problems such as synthetic aperture radar (SAR) image formation. ASR performance characteristics can be varied through the choice of filter order, l(1)- or l(2)-norm filter vector constraints and a separable or nonseparable multidimensional implementation. The author compares simulated point scattering SAR imagery produced by the ASR, MVM, and MUSIC algorithms and illustrates ASR performance on three sets of collected SAR imagery.

  17. Estimation of penetration of forest canopies by Interferometric SAR measurements

    NASA Technical Reports Server (NTRS)

    Rodriguez, Ernesto; Michel, Thierry R.; Harding, David J.

    1995-01-01

    In contrast to traditional Synthetic Aperture Radar (SAR), an Interferometric SAR (INSAR) yields two additional measurements: the phase difference and the correlation between the two interferometric channels. The phase difference has been used to estimate topographic height. For homogeneous surfaces, the correlation depends on the system signal-to-noise (SNR) ratio, the interferometer parameters, and the local slope. In the presence of volume scattering, such as that encountered in vegetation canopies, the correlation between the two channels is also dependent on the degree of penetration of the radiation into the scattering medium. In this paper, we propose a method for removing system and slope effects in order to obtain the decorrelation due to penetration alone. The sensitivities and accuracy of the proposed method are determined by Monte Carlo experiments, and we show that the proposed technique has sufficient sensitivity to provide penetration measurements for airborne SAR systems. Next, we provide a theoretical model to estimate the degree of penetration in a way which is independent of the details of the scattering medium. We also present a model for the correlation from non-homogeneous layers. We assess the sensitivity of the proposed inversion technique to these inhomogeneous situations. Finally, we present a comparison of the interferometric results against in situ data obtained by an airborne laser profilometer which provides a direct measurement of tree height and an estimate of the vegetation density profile in the forested areas around Mt. Adams, WA.

  18. Affordable miniaturized SAR for tactical UAV applications

    NASA Astrophysics Data System (ADS)

    Sloan, George R.; Dubbert, Dale F.

    2004-08-01

    Sandia"s fielded and experimental SAR systems are well known for their real time, high resolution imagery. Previous designs, such as the Lynx radar, have been successfully demonstrated on medium-payload UAVs, including Predator and Fire Scout. However, fielding a high performance SAR sensor on even smaller (sub-50 pound payload) UAVs will require at least a 5x reduction in size, weight, and cost. This paper gives an overview of Sandia"s system concept and roadmap for near-term SAR miniaturization. Specifically, the "miniSAR" program, which plans to demonstrate a 25 pound system with 4 inch resolution in early 2005, is detailed. Accordingly, the conceptual approach, current status, design tradeoffs, and key facilitating technologies are reviewed. Lastly, future enhancements and directions are described, such as the follow-on demonstration of a sub-20 pound version with multi-mode (SAR/GMTI) capability.

  19. Interferometric SAR imaging by transmitting stepped frequency chaotic noise signals

    NASA Astrophysics Data System (ADS)

    Zhang, Yunhua; Gu, Xiang; Zhai, Wenshuai; Dong, Xiao; Shi, Xiaojin; Kang, Xueyan

    2015-10-01

    Noise radar has been applied in many fields since it was proposed more than 50 years ago. However, it has not been applied to interferometric SAR imaging yet as far as we know. This paper introduces our recent work on interferometric noise radar. An interferometric SAR system was developed which can transmit both chirp signal and chaotic noise signal (CNS) at multiple carrier frequencies. An airborne experiment with this system by transmitting both signals was carried out, and the data were processed to show the capability of interferometric SAR imaging with CNS. The results shows that although the interferometric phase quality of CNS is degraded due to the signal to noise ratio (SNR) is lower compared with that of chirp signal, we still can get satisfied DEM after multi-looking processing. Another work of this paper is to apply compressed sensing (CS) theory to the interferometric SAR imaging with CNS. The CS theory states that if a signal is sparse, then it can be accurately reconstructed with much less sampled data than that regularly required according to Nyquist Sampling Theory. To form a structured random matrix, if the transmitted signal is of fixed waveform, then random subsampling is needed. However, if the transmitted signal is of random waveform, then only uniform subsampling is needed. This is another advantage of noise signal. Both the interferometric phase images and the DEMs by regular method and by CS method are processed with results compared. It is shown that the degradation of interferometric phases due to subsampling is larger than that of amplitude image.

  20. SARS and population health technology.

    PubMed

    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. PMID:12857670

  1. Analysis of the local worst-case SAR exposure caused by an MRI multi-transmit body coil in anatomical models of the human body.

    PubMed

    Neufeld, Esra; Gosselin, Marie-Christine; Murbach, Manuel; Christ, Andreas; Cabot, Eugenia; Kuster, Niels

    2011-08-01

    Multi-transmit coils are increasingly being employed in high-field magnetic resonance imaging, along with a growing interest in multi-transmit body coils. However, they can lead to an increase in whole-body and local specific absorption rate (SAR) compared to conventional body coils excited in circular polarization for the same total incident input power. In this study, the maximum increase of SAR for three significantly different human anatomies is investigated for a large 3 T (128 MHz) multi-transmit body coil using numerical simulations and a (generalized) eigenvalue-based approach. The results demonstrate that the increase of SAR strongly depends on the anatomy. For the three models and normalization to the sum of the rung currents squared, the whole-body averaged SAR increases by up to a factor of 1.6 compared to conventional excitation and the peak spatial SAR (averaged over any 10 cm(3) of tissue) by up to 13.4. For some locations the local averaged SAR goes up as much as 800 times (130 when looking only at regions where it is above 1% of the peak spatial SAR). The ratio of the peak spatial SAR to the whole-body SAR increases by a factor of up to 47 and can reach values above 800. Due to the potentially much larger power deposition, additional, preferably patient-specific, considerations are necessary to avoid injuries by such systems.

  2. History of SAR at Lockheed Martin (previously Goodyear Aerospace)

    NASA Astrophysics Data System (ADS)

    Lasswell, Stephen W.

    2005-05-01

    Synthetic Aperture Radar (SAR) was invented by Carl Wiley at Goodyear Aircraft Company in Goodyear, Arizona, in 1951. From that time forward, as the company became Goodyear Aerospace Corporation, Loral Corporation, and finally Lockheed Martin Corporation, the Arizona employees past and present played a long and storied role in numerous SAR firsts. These include the original SAR patent (known as Simultaneous Doppler Buildup), the first demonstration SAR and flight test, the first operational SAR system, the first operational SAR data link, the first 5-foot resolution operational SAR system, the first 1-foot resolution SAR system, and the first large scale SAR digital processor. The company has installed and flown over five hundred SAR systems on more than thirty different types of aircraft for numerous countries throughout the world. The company designed and produced all of the evolving high performance SAR systems for the U. S. Air Force SR-71 "Blackbird" spy plane throughout its entire operational history, spanning some twenty-nine years. Recent SAR accomplishments include long-range standoff high performance SAR systems, smaller high resolution podded SAR systems for fighter aircraft, and foliage penetration (FOPEN) SAR. The company is currently developing the high performance SAR/MTI (Moving Target Indication) radar for the Army Aerial Common Sensor (ACS) system.

  3. Next generation SAR demonstration on space station

    SciTech Connect

    Edelstein, Wendy; Kim, Yunjin; Freeman, Anthony; Jordan, Rolando

    1999-01-22

    This paper describes the next generation synthetic aperture radar (SAR) that enables future low cost space-borne radar missions. In order to realize these missions, we propose to use an inflatable, membrane, microstrip antenna that is particularly suitable for low frequency science radar missions. In order to mitigate risks associated with this revolutionary technology, the space station demonstration will be very useful to test the long-term survivability of the proposed antenna. This experiment will demonstrate several critical technology challenges associated with space-inflatable technologies. Among these include space-rigidization of inflatable structures, controlled inflation deployment, flatness and uniform separation of thin-film membranes and RF performance of membrane microstrip antennas. This mission will also verify the in-space performance of lightweight, high performance advanced SAR electronics. Characteristics of this SAR instrument include a capability for high resolution polarimetric imaging. The mission will acquire high quality scientific data using this advanced SAR to demonstrate the utility of these advanced technologies. We will present an inflatable L-band SAR concept for commercial and science applications and a P-band design concept to validate the Biomass SAR mission concept. The ionospheric effects on P-band SAR images will also be examined using the acquired data.

  4. SAR image formation toolbox for MATLAB

    NASA Astrophysics Data System (ADS)

    Gorham, LeRoy A.; Moore, Linda J.

    2010-04-01

    While many synthetic aperture radar (SAR) image formation techniques exist, two of the most intuitive methods for implementation by SAR novices are the matched filter and backprojection algorithms. The matched filter and (non-optimized) backprojection algorithms are undeniably computationally complex. However, the backprojection algorithm may be successfully employed for many SAR research endeavors not involving considerably large data sets and not requiring time-critical image formation. Execution of both image reconstruction algorithms in MATLAB is explicitly addressed. In particular, a manipulation of the backprojection imaging equations is supplied to show how common MATLAB functions, ifft and interp1, may be used for straight-forward SAR image formation. In addition, limits for scene size and pixel spacing are derived to aid in the selection of an appropriate imaging grid to avoid aliasing. Example SAR images generated though use of the backprojection algorithm are provided given four publicly available SAR datasets. Finally, MATLAB code for SAR image reconstruction using the matched filter and backprojection algorithms is provided.

  5. First Results from an Airborne Ka-band SAR Using SweepSAR and Digital Beamforming

    NASA Technical Reports Server (NTRS)

    Sadowy, Gregory; Ghaemi, Hirad; Hensley, Scott

    2012-01-01

    NASA/JPL has developed SweepSAR technique that breaks typical Synthetic Aperture Radar (SAR) trade space using time-dependent multi-beam DBF on receive. Developing SweepSAR implementation using array-fed reflector for proposed DESDynI Earth Radar Mission concept. Performed first-of-a-kind airborne demonstration of the SweepSAR concept at Ka-band (35.6 GHz). Validated calibration and antenna pattern data sufficient for beam forming in elevation. (1) Provides validation evidence that the proposed Deformation Ecosystem Structure Dynamics of Ice (DESDynI) SAR architecture is sound. (2) Functions well even with large variations in receiver gain / phase. Future plans include using prototype DESDynI SAR digital flight hardware to do the beam forming in real-time onboard the aircraft.

  6. Change detection in quad and dual pol, single- and bi-frequency SAR data

    NASA Astrophysics Data System (ADS)

    Nielsen, Allan A.; Conradsen, Knut; Skriver, Henning

    2015-10-01

    When the covariance matrix representation is used for multi-look polarimetric synthetic aperture radar (SAR) data, the complex Wishart distribution applies. Based on this distribution a likelihood ratio test statistic for equality of two complex variance-covariance matrices and an associated p-value are given. In a case study airborne EMISAR C- and L-band SAR images covering agricultural fields and wooded areas near Foulum, Denmark, are used in single- and bi-frequency, bi-temporal change detection with full and dual polarimetry data.

  7. NASA/JPL Aircraft SAR Workshop Proceedings

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  8. Primary studies of Chinese spaceborne SAR

    NASA Technical Reports Server (NTRS)

    Wang, Zhen-Song; Wu, Guo-Xiang; Guo, Hua-Dong; Wei, Zhong-Quan; Zhu, Min-Hui

    1993-01-01

    The primary studies on spaceborne synthetic aperture radar (SAR) in China are discussed. The SAR will be launched aboard a Chinese satellite and operated at L-band with HH polarization. The purpose of the mission in consideration is dedicated to resources and environment uses, especially to natural disaster monitoring. The ground resolution is designed as 25 m x 25 m for detailed mode and 100 m x 100 m for wide scan-SAR mode. The off-nadir angle can be varied from 20 to 40 deg. The key system concepts are introduced.

  9. SAR observations of coastal zone conditions

    NASA Technical Reports Server (NTRS)

    Meadows, G. A.; Kasischke, E. S.; Shuchman, R. A.

    1980-01-01

    Applications of Synthetic Aperture Radar (SAR) technology to the observation of coastal zones phenomena are detailed. The conditions observed include gravity wave detection, surf zone location, surface currents, and long-period 'surf beats'. Algorithms have been developed and successfully tested that determine significant wave and current parameters from the sea surface backscatter of microwave energy. Doppler information from the SAR optical correlator allows a rough estimation of near shore surface flow velocities that has been found in agreement with both theory and in situ observations as well. Seasat SAR data of the Scotland and North Carolina coasts are considered, as well as the results of bathymetric updating of coastal area charts.

  10. Similarity measures of full polarimetric SAR images fusion for improved SAR image matching

    NASA Astrophysics Data System (ADS)

    Ding, H.

    2015-06-01

    China's first airborne SAR mapping system (CASMSAR) developed by Chinese Academy of Surveying and Mapping can acquire high-resolution and full polarimetric (HH, HV, VH and VV) Synthetic aperture radar (SAR) data. It has the ability to acquire X-band full polarimetric SAR data at a resolution of 0.5m. However, the existence of speckles which is inherent in SAR imagery affects visual interpretation and image processing badly, and challenges the assumption that conjugate points appear similar to each other in matching processing. In addition, researches show that speckles are multiplicative speckles, and most similarity measures of SAR image matching are sensitive to them. Thus, matching outcomes of SAR images acquired by most similarity measures are not reliable and with bad accuracy. Meanwhile, every polarimetric SAR image has different backscattering information of objects from each other and four polarimetric SAR data contain most basic and a large amount of redundancy information to improve matching. Therefore, we introduced logarithmically transformation and a stereo matching similarity measure into airborne full polarimetric SAR imagery. Firstly, in order to transform the multiplicative speckles into additivity ones and weaken speckles' influence on similarity measure, logarithmically transformation have to be taken to all images. Secondly, to prevent performance degradation of similarity measure caused by speckles, measure must be free or insensitive of additivity speckles. Thus, we introduced a stereo matching similarity measure, called Normalized Cross-Correlation (NCC), into full polarimetric SAR image matching. Thirdly, to take advantage of multi-polarimetric data and preserve the best similarity measure value, four measure values calculated between left and right single polarimetric SAR images are fused as final measure value for matching. The method was tested for matching under CASMSAR data. The results showed that the method delivered an effective

  11. Investigating earthquake scaling relationships from a 15 year archive of InSAR-derived earthquake models

    NASA Astrophysics Data System (ADS)

    Funning, G. J.; Ferreira, A. M.; Parsons, B. E.

    2008-12-01

    In the 15 years since the first InSAR study of the 1992 Landers earthquake, the first event to be studied using InSAR, over 50 events have been studied wholly or jointly using InSAR. This constitutes a rich archive of published studies that can be mined for information on earthquake phenomenology. Empirical earthquake scaling relationships, as can be inferred from estimates of fault dimensions, slip and moment for multiple earthquakes, are extensively used in seismic hazard forecasting, and also constitute a means of placing constraints on the bulk mechanical behaviour of the seismogenic upper crust. As a source of such data, studies that utilise information from InSAR have an advantage over seismic methods in that in many cases, a key parameter, the fault length, can be measured directly from the observations. In addition, in cases of good interferogram coherence, the high spatial density of surface deformation observations that InSAR affords can place tight constraints on fault width and other important parameters. We present here a preliminary survey of earthquake scaling relationships as supported by the existing archive of InSAR earthquake studies. We find that for events with Mw > 6, the data support moment scaling with the square of fault length, in keeping with the studies of Scholz and others, and imply proportionality between fault average slip and fault length. There are currently too few datapoints for great earthquakes (Mw > 8) to assess any proposed change in scaling for such events. Scatterplots of average slip versus fault length show two broad fields -- an area of high slip-to-length ratios (> 2 × 10-5) which are predominantly associated with faults with low long-term slip rates, predominantly from intraplate settings, and an area of lower slip-to-length ratios (< 2 × 10-5) which typically are larger events from faults with higher long-term slip rates (e.g. the North Anatolian and Kunlun faults, and the Peru-Chile subduction zone). In addition

  12. Atmosphere Observations by Geosynchronous SARs

    NASA Astrophysics Data System (ADS)

    Monti guarnieri, Andrea; Rocca, Fabio; Wadge, Geoff; Schulz, Detlef

    2014-05-01

    We analyze different geosynchronous Synthetic Aperture RADAR concepts aimed to get both tropospheric and ionospheric delay maps with a revisit time of minutes and sub-continental coverage. Such products could be used either to compensate the delay in LEO-SAR missions and GNSS, or to generate integrated water-vapor maps to be used for Numerical Weather Forecast. The system exploits the principle of RADAR location, by transmitting a pulse with a suitable bandwidth, and the residual non-zero eccentricity of COMmunication SATellites. Different concepts are proposed as payload in COMSAT, or constellations of small satellites, that is monostatic or bistatic/multistatic RADARS. The selection of the best frequency, from L to Ku, and the analysis of performances is presented.

  13. SEASAT SAR performance evaluation study

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The performance of the SEASAT synthetic aperture radar (SAR) sensor was evaluated using data processed by the MDA digital processor. Two particular aspects are considered the location accuracy of image data, and the calibration of the measured backscatter amplitude of a set of corner reflectors. The image location accuracy was assessed by selecting identifiable targets in several scenes, converting their image location to UTM coordinates, and comparing the results to map sheets. The error standard deviation is measured to be approximately 30 meters. The amplitude was calibrated by measuring the responses of the Goldstone corner reflector array and comparing the results to theoretical values. A linear regression of the measured against theoretical values results in a slope of 0.954 with a correlation coefficient of 0.970.

  14. SAR Imagery Applied to the Monitoring of Hyper-Saline Deposits: Death Valley Example (CA)

    NASA Technical Reports Server (NTRS)

    Lasne, Yannick; Paillou, Philippe; Freeman, Anthony; Chapman, Bruce

    2009-01-01

    The present study aims at understanding the influence of salinity on the dielectric constant of soils and then on the backscattering coeff cients recorded by airborne/spaceborne SAR systems. Based on dielectric measurements performed over hyper-saline deposits in Death Valley (CA), as well as laboratory electromagnetic characterization of salts and water mixtures, we used the dielectric constants as input parameters of analytical IEM simulations to model both the amplitude and phase behaviors of SAR signal at C, and L-bands. Our analytical simulations allow to reproduce specif c copolar signatures recorded in SAR data, corresponding to the Cottonball Basin saltpan. We also propose the copolar backscattering ratio and phase difference as indicators of moistened and salt-affected soils. More precisely, we show that these copolar indicators should allow to monitor the seasonal variations of the dielectric properties of saline deposits.

  15. Comparisons of wind speed retrieval methods on C-band multi-polarization SAR measurements

    NASA Astrophysics Data System (ADS)

    Ren, Lin; Yang, Jingsong; Zheng, Gang; Wang, Juan; Wang, Difeng

    2014-10-01

    This paper compares the wind speed retrieval methods on C-band multi-polarization SAR measurements to find out the most appropriate one for each polarization data. The RADARSAT-2 SAR quad-polarization (VV+HH+VH+HV) data and NDBC buoy wind data were collocated. For VVpolarization, the retrieved wind speed are compared among four geophysical model function (GMF). For HH polarization, the retrieved wind speed are compared among four polarization ratio model (PR) based on CMOD5 GMF. For VH polarization, the retrieved wind speed are compared between two linear models. Comparisons show all of three polarimetric SAR data have the ability of retrieving wind speed. Based on the error analysis, the commendatory methods are proposed for each polarization.

  16. Using GNSS signals as a proxy for SAR signals: Correcting ionospheric defocusing

    NASA Astrophysics Data System (ADS)

    Mannix, Christopher R.; Belcher, David P.; Cannon, Paul S.; Angling, Matthew J.

    2016-02-01

    Ultrahigh frequency space-based synthetic aperture radar (SAR) can suffer from the degrading effects of a scintillating ionosphere which modulates both the phase and the amplitude of the radar signal. In this paper, we use Global Navigation Satellite System (GNSS) signals to synthesize an L-band SAR point spread function (PSF). The process of transforming the GNSS signal to the equivalent SAR PSF is described. The synthesized PSF is used to explore the possibility of using a phase correction determined from a point target in a SAR image to correct the ionospheric degradation. GNSS data recorded on equatorial Ascension Island during scintillation events are used to test the feasibility of this approach by applying a phase correction to one GNSS receiver from another located along a magnetic east-west baseline. The peak-to-sidelobe ratios of the synthesized L-band SAR point spread functions before and after the correction are compared, and it is shown that this approach improves the L-band PSF over distances of ~3000 m in the ionosphere, corresponding to 6000 m on the ground.

  17. Structural classification of marshes with Polarimetric SAR highlighting the temporal mapping of marshes exposed to oil

    USGS Publications Warehouse

    Ramsey III, Elijah W.; Rangoonwala, Amina; Jones, Cathleen E.

    2015-01-01

    Empirical relationships between field-derived Leaf Area Index (LAI) and Leaf Angle Distribution (LAD) and polarimetric synthetic aperture radar (PolSAR) based biophysical indicators were created and applied to map S. alterniflora marsh canopy structure. PolSAR and field data were collected near concurrently in the summers of 2010, 2011, and 2012 in coastal marshes, and PolSAR data alone were acquired in 2009. Regression analyses showed that LAI correspondence with the PolSAR biophysical indicator variables equaled or exceeded those of vegetation water content (VWC) correspondences. In the final six regressor model, the ratio HV/VV explained 49% of the total 77% explained LAI variance, and the HH-VV coherence and phase information accounted for the remainder. HV/HH dominated the two regressor LAD relationship, and spatial heterogeneity and backscatter mechanism followed by coherence information dominated the final three regressor model that explained 74% of the LAD variance. Regression results applied to 2009 through 2012 PolSAR images showed substantial changes in marsh LAI and LAD. Although the direct cause was not substantiated, following a release of freshwater in response to the 2010 Deepwater Horizon oil spill, the fairly uniform interior marsh structure of 2009 was more vertical and dense shortly after the oil spill cessation. After 2010, marsh structure generally progressed back toward the 2009 uniformity; however, the trend was more disjointed in oil impact marshes.             

  18. Formation Flying for Distributed InSAR

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel P.; Murray, Emmanuell A.; Ploen, Scott R.; Gromov, Konstantin G.; Chen, Curtis W.

    2006-01-01

    We consider two spacecraft flying in formation to create interferometric synthetic aperture radar (InSAR). Several candidate orbits for such in InSar formation have been previously determined based on radar performance and Keplerian orbital dynamics. However, with out active control, disturbance-induced drift can degrade radar performance and (in the worst case) cause a collision. This study evaluates the feasibility of operating the InSAR spacecraft as a formation, that is, with inner-spacecraft sensing and control. We describe the candidate InSAR orbits, design formation guidance and control architectures and algorithms, and report the (Delta)(nu) and control acceleration requirements for the candidate orbits for several tracking performance levels. As part of determining formation requirements, a formation guidance algorithm called Command Virtual Structure is introduced that can reduce the (Delta)(nu) requirements compared to standard Leader/Follower formation approaches.

  19. SAR/LANDSAT image registration study

    NASA Technical Reports Server (NTRS)

    Murphrey, S. W. (Principal Investigator)

    1978-01-01

    The author has identified the following significant results. Temporal registration of synthetic aperture radar data with LANDSAT-MSS data is both feasible (from a technical standpoint) and useful (from an information-content viewpoint). The greatest difficulty in registering aircraft SAR data to corrected LANDSAT-MSS data is control-point location. The differences in SAR and MSS data impact the selection of features that will serve as a good control points. The SAR and MSS data are unsuitable for automatic computer correlation of digital control-point data. The gray-level data can not be compared by the computer because of the different response characteristics of the MSS and SAR images.

  20. An algorithm for segmenting polarimetric SAR imagery

    NASA Astrophysics Data System (ADS)

    Geaga, Jorge V.

    2015-05-01

    We have developed an algorithm for segmenting fully polarimetric single look TerraSAR-X, multilook SIR-C and 7 band Landsat 5 imagery using neural nets. The algorithm uses a feedforward neural net with one hidden layer to segment different surface classes. The weights are refined through an iterative filtering process characteristic of a relaxation process. Features selected from studies of fully polarimetric complex single look TerraSAR-X data and multilook SIR-C data are used as input to the net. The seven bands from Landsat 5 data are used as input for the Landsat neural net. The Cloude-Pottier incoherent decomposition is used to investigate the physical basis of the polarimetric SAR data segmentation. The segmentation of a SIR-C ocean surface scene into four classes is presented. This segmentation algorithm could be a very useful tool for investigating complex polarimetric SAR phenomena.

  1. Polarimetric SAR Interferometry Evaluation in Mangroves

    NASA Technical Reports Server (NTRS)

    Lee, Seung-Kuk; Fatoyinbo,Temilola; Osmanoglu, Batuhan; Sun, Guoqing

    2014-01-01

    TanDEM-X (TDX) enables to generate an interferometric coherence without temporal decorrelation effect that is the most critical factor for a successful Pol-InSAR inversion, as have recently been used for forest parameter retrieval. This paper presents mangrove forest height estimation only using single-pass/single-baseline/dual-polarization TDX data by means of new dual-Pol-InSAR inversion technique. To overcome a lack of one polarization in a conventional Pol- InSAR inversion (i.e. an underdetermined problem), the ground phase in the Pol-InSAR model is directly estimated from TDX interferograms assuming flat underlying topography in mangrove forest. The inversion result is validated against lidar measurement data (NASA's G-LiHT data).

  2. SAR Polarimetry for Oil at Sea Observation

    NASA Astrophysics Data System (ADS)

    Migliaccio, M.; Nunziata, F.

    2013-03-01

    Synthetic aperture radar (SAR) oil slick observation is a topic of great applicative relevance which has been physically recast by a set of new polarimetric approaches that, exploiting the departure from Bragg scattering, allow observing oil at sea in a very robust and effective way. In this study, these polarimetric approaches are reviewed and their performances are discussed with respect to some thought experiments undertaken on quad-pol full-resolution L- and C-band SAR data.

  3. RADARSAT high throughput SAR processor development

    NASA Technical Reports Server (NTRS)

    George, P.

    1986-01-01

    MacDonald Dettwiler & Associates has been involved with the Canadian Radarsat (RSAT) project for a number of years. This included Phase A definition studies and for the past two years, Phase B ground station design and processor prototyping efforts. The current baseline design for the SAR processing facility (SARDPF) is described along with its requirements and functional decomposition. This forms the context for then discussing the prototype SAR processor and extensions necessary to meet current ground station processing requirements.

  4. Ionospheric Specifications for SAR Interferometry (ISSI)

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  5. SARS: Key factors in crisis management.

    PubMed

    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.

  6. Adsorption Refrigeration System

    SciTech Connect

    Wang, Kai; Vineyard, Edward Allan

    2011-01-01

    Adsorption refrigeration is an environmentally friendly cooling technology which could be driven by recovered waste heat or low-grade heat such as solar energy. In comparison with absorption system, an adsorption system has no problems such as corrosion at high temperature and salt crystallization. In comparison with vapor compression refrigeration system, it has the advantages of simple control, no moving parts and less noise. This paper introduces the basic theory of adsorption cycle as well as the advanced adsorption cycles such as heat and mass recovery cycle, thermal wave cycle and convection thermal wave cycle. The types, characteristics, advantages and drawbacks of different adsorbents used in adsorption refrigeration systems are also summarized. This article will increase the awareness of this emerging cooling technology among the HVAC engineers and help them select appropriate adsorption systems in energy-efficient building design.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  8. Remotely Sensing Tundra Fire Impacts Using InSAR

    NASA Astrophysics Data System (ADS)

    Liu, L.; Schaefer, K. M.; Jafarov, E. E.; Williams, C. A.; Rogan, J.; Zebker, H. A.

    2013-12-01

    Fire is a major disturbance affecting the arctic tundra and boreal forests, with a significant impacts on the ecosystem, soil hydrology, carbon cycling, and permafrost. The increasing trend in frequency and severity of large fires since 1980, associated with progressively drier conditions, is expected to continue and lead to still greater impacts. In this study, we explore the use of Interferometric Synthetic Aperture Radar (InSAR) to map and quantify several results of tundra fires, including fire severity, the increase in permafrost active layer thickness (ALT), and changes in organic layer thickness. Here we present as an example observations of the Anaktuvuk River fire on the North Slope of Alaska, which burned over 1,000 km2 of tundra in the summer of 2007. Fire causes an abrupt change in the surface scattering characteristics and results in a large drop in InSAR coherence. The magnitude of coherence loss is proportional to the amount of vegetation burned, and thus fire severity. Coherence between two PALSAR images taken by the Japanese ALOS satellite before and after the Anaktuvuk River fire shows a spatial pattern consistent with a map of burn severity based on optical MODIS images using differential Normalized Burn Ratio. Additionally, we used InSAR to calculate the seasonal ground subsidence for the 2006 and 2009 thaw seasons representing pre- and post-fire conditions, and estimated the change in ALT using a retrieval algorithm. Our results are consistent with the 8 to 24 cm ALT increases derived from in situ probing measurements, which we relate to the change in the organic layer thickness due to the fire. Our results illustrate the potential of InSAR for remote sensing of fire impacts in Arctic regions. (a) Burn severity for the Anaktuvuk Rivre Fire based on differential Normalized Burn Ratio (dNBR) from MODIS images. (b) Interferometric coherence loss due to the fire. Spatial mean has been subtracted. Negative values (yellow and red colors) indicate

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

    ERIC Educational Resources Information Center

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

    2005-01-01

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

  10. 20. OVERVIEW OF SAR3 COMPLEX, SHOWING FORMER RESIDENTIAL AREA, SAR3 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. OVERVIEW OF SAR-3 COMPLEX, SHOWING FORMER RESIDENTIAL AREA, SAR-3 SWITCH RACK, MAINTENANCE YARD, AND GREENSPOT BRIDGE. NOTE ALSO LARGE PIPE CONDUCTING TAILRACE WATER INTO IRRIGATION SYSTEM. VIEW TO SOUTHWEST. - Santa Ana River Hydroelectric System, Redlands, San Bernardino County, CA

  11. Landslide Monitoring in Three Gorges Area Using D-InSAR and PS-InSAR

    NASA Astrophysics Data System (ADS)

    Tantianuparp, Peraya; Shi, Xuguo; Liao, Mingsheng; Zhang, Lu; Balz, Timo

    2013-01-01

    Landslides are a major hazard in steep mountainous area, like the Three Gorges area. The Three Gorges dam was built on a geologically unstable zone. The geological pressures from the rising water level caused by the dam and the deforestation have further increased the possibility for landslides in the area. Many landslide monitoring techniques are applied to analysis, forecast, and control landslides in this area. D-InSAR and PS-InSAR, the time series InSAR analysis, are used for terrain motion detection and to estimate displacement trends. In this paper, SAR data from systems with different wavelengths, like the C-band ASAR, the L-band PALSAR, and the high-resolution TerraSAR-X X-band data, are used.

  12. Landslide Monitoring in Three Gorges Area Using D-InSAR and PS-InSAR

    NASA Astrophysics Data System (ADS)

    Tantianuparp, Peraya; Shi, Xuguo; Liao, Mingsheng; Zhang, Lu; Balz, Timo

    2013-01-01

    Landslides are a major hazard in steep mountainous area. The Three Gorges dam was built on a geologically unstable zone. The geological pressures from the rising water level caused by the dam and the deforestation have increased the possibility for landslides in the area. Many landslide monitoring techniques are applied to analysis, forecast, and control land-slides in this area. D-InSAR and PS-InSAR, the time series InSAR analysis, are used for terrain motion detection and to estimate displacement trends. In this paper, SAR data from systems with different wavelengths, like the C-band ASAR, the L-band ALOS, and the high-resolution TerraSAR-X X-band data, are used.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  14. Performance evaluation of SAR/GMTI algorithms

    NASA Astrophysics Data System (ADS)

    Garber, Wendy; Pierson, William; Mcginnis, Ryan; Majumder, Uttam; Minardi, Michael; Sobota, David

    2016-05-01

    There is a history and understanding of exploiting moving targets within ground moving target indicator (GMTI) data, including methods for modeling performance. However, many assumptions valid for GMTI processing are invalid for synthetic aperture radar (SAR) data. For example, traditional GMTI processing assumes targets are exo-clutter and a system that uses a GMTI waveform, i.e. low bandwidth (BW) and low pulse repetition frequency (PRF). Conversely, SAR imagery is typically formed to focus data at zero Doppler and requires high BW and high PRF. Therefore, many of the techniques used in performance estimation of GMTI systems are not valid for SAR data. However, as demonstrated by papers in the recent literature,1-11 there is interest in exploiting moving targets within SAR data. The techniques employed vary widely, including filter banks to form images at multiple Dopplers, performing smear detection, and attempting to address the issue through waveform design. The above work validates the need for moving target exploitation in SAR data, but it does not represent a theory allowing for the prediction or bounding of performance. This work develops an approach to estimate and/or bound performance for moving target exploitation specific to SAR data. Synthetic SAR data is generated across a range of sensor, environment, and target parameters to test the exploitation algorithms under specific conditions. This provides a design tool allowing radar systems to be tuned for specific moving target exploitation applications. In summary, we derive a set of rules that bound the performance of specific moving target exploitation algorithms under variable operating conditions.

  15. Multiresolution analysis of SAR data

    NASA Astrophysics Data System (ADS)

    Hummel, Robert

    1993-01-01

    The 'Multiresolution Analysis of SAR Data' program supported research work in five areas. Geometric hashing theory can now be viewed as a Bayesian approach to object recognition. False alarm rates can be greatly reduced by using certain enhancements and modifications developed under this project. Geometric hashing algorithms now exist for the Connection Machine. Recognition of synthetically-produced dot arrays was demonstrated using a model base of 1024 objects. The work represents a substantial advance over existing model-based vision capabilities. Algorithms were developed for determining the translation and rotation of a sensor given only the image flow field data. These are new algorithms, and are much more stable than existing computer vision algorithms for this task. The algorithms might provide independent verification of gyroscopic data, or might be used to compute relative motion with respect to a moving scene object, or may be useful for motion-based segmentation. Our theories explaining the Dempster/Shafer calculus and developing new uncertainty reasoning calculi were extended, and presented at a conference and were incorporated into the Bayesian interpretation of geometric hashing. 'Wavelet Slice Theorem' was developed in several different versions, any of which yields an alternate approach to image formation. The result may well provide a more stable approach to image formation than the standard Fourier-based projection slide theorem, since interpolation of unknown spectra values is better-founded.

  16. Adsorption of ferrous ions onto montmorillonites

    NASA Astrophysics Data System (ADS)

    Qin, Dawei; Niu, Xia; Qiao, Min; Liu, Gang; Li, Hongxin; Meng, Zhenxiao

    2015-04-01

    The adsorption of Fe (II) onto montmorillonites was investigated through initial concentration, contact time, pH and temperature. During the whole adsorption process, the ascorbic acid (Vitamin C) was added as a kind of antioxidant, at the same time, deionized water (after boiling) and nitrogen protection were also used to avoid oxidation. The Fe2+/Fetotal ratio of the iron exists in the Fe-montmorillonites was found more than 95%. Two kinetic models, including pseudo-first-order and pseudo-second-order model, were used to analyze the adsorption process of Fe (II) on montmorillonites. The results of our study showed that adsorption process fitted with pseudo-second-order well. Adsorption isotherms showed that Langmuir model was better than Freundlich model. The thermodynamic parameters ΔG0 and ΔH0 were 3.696 kJ/mol and 6.689 kJ/mol (we just gave the values at 298 K), respectively. The positive values at different temperatures showed that the adsorption process was non-spontaneous and endothermic. The characteristics of materials were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Surface area and porosity analyzer, Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC) and Zeta potential distribution.

  17. Quad-polarization SAR features of ocean currents

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, V.; Kozlov, I.; Chapron, B.; Johannessen, J. A.

    2014-09-01

    A methodology is demonstrated to exploit the polarization sensitivity of high-resolution radar measurements to interpret and quantify upper ocean dynamics. This study particularly illustrates the potential of quad-polarization synthetic aperture radar (SAR) measurements. The analysis relies on essential characteristics of the electromagnetic scattering mechanisms and hydrodynamical principles. As the relaxation scale of centimeter-scale ocean surface scatters is typically small, radar signal anomalies associated with surface manifestations of the upper ocean dynamics on spatial scales exceeding 100 m are mostly dominated by nonresonant and nonpolarized scatters. These "scalar" contributions can thus efficiently trace local breaking and near-breaking areas, caused by surface current variations. Using dual copolarized measurements, the polarized Bragg-type radar scattering is isolated by considering the difference (PD) between vertically and horizontally polarized radar signals. The nonpolarized (NP) contribution associated with wave breaking is then deduced, using the measured polarization ratio (PR) between polarized signals. Considering SAR scenes depicting various surface manifestations of the upper ocean dynamics (internal waves, mesoscale surface current features, and SST front), the proposed methodology and set of decompositions (PD, PR, and NP) efficiently enable the discrimination between surface manifestation of upper ocean dynamics and wind field variability. Applied to quad-polarized SAR images, such decompositions further provide unique opportunities to more directly assess the cross-polarized (CP for HV or VH) signal sensitivity to surface roughness changes. As demonstrated, such an analysis unambiguously demonstrates and quantitatively evaluates the relative impact of breakers on cross-polarized signals under low to moderate wind conditions.

  18. A Simple Adsorption Experiment

    ERIC Educational Resources Information Center

    Guirado, Gonzalo; Ayllon, Jose A.

    2011-01-01

    The study of adsorption phenomenon is one of the most relevant and traditional physical chemistry experiments performed by chemistry undergraduate students in laboratory courses. In this article, we describe an easy, inexpensive, and straightforward way to experimentally determine adsorption isotherms using pieces of filter paper as the adsorbent…

  19. Severe Acute Respiratory Syndrome (SARS) Coronavirus ORF8 Protein Is Acquired from SARS-Related Coronavirus from Greater Horseshoe Bats through Recombination

    PubMed Central

    Lau, Susanna K. P.; Feng, Yun; Chen, Honglin; Luk, Hayes K. H.; Yang, Wei-Hong; Li, Kenneth S. M.; Zhang, Yu-Zhen; Huang, Yi; Song, Zhi-Zhong; Chow, Wang-Ngai; Fan, Rachel Y. Y.; Ahmed, Syed Shakeel; Yeung, Hazel C.; Lam, Carol S. F.; Cai, Jian-Piao; Wong, Samson S. Y.; Chan, Jasper F. W.; Yuen, Kwok-Yung

    2015-01-01

    ABSTRACT Despite the identification of horseshoe bats as the reservoir of severe acute respiratory syndrome (SARS)-related coronaviruses (SARSr-CoVs), the origin of SARS-CoV ORF8, which contains the 29-nucleotide signature deletion among human strains, remains obscure. Although two SARS-related Rhinolophus sinicus bat CoVs (SARSr-Rs-BatCoVs) previously detected in Chinese horseshoe bats (Rhinolophus sinicus) in Yunnan, RsSHC014 and Rs3367, possessed 95% genome identities to human and civet SARSr-CoVs, their ORF8 protein exhibited only 32.2 to 33% amino acid identities to that of human/civet SARSr-CoVs. To elucidate the origin of SARS-CoV ORF8, we sampled 348 bats of various species in Yunnan, among which diverse alphacoronaviruses and betacoronaviruses, including potentially novel CoVs, were identified, with some showing potential interspecies transmission. The genomes of two betacoronaviruses, SARSr-Rf-BatCoV YNLF_31C and YNLF_34C, from greater horseshoe bats (Rhinolophus ferrumequinum), possessed 93% nucleotide identities to human/civet SARSr-CoV genomes. Although these two betacoronaviruses displayed lower similarities than SARSr-Rs-BatCoV RsSHC014 and Rs3367 in S protein to civet SARSr-CoVs, their ORF8 proteins demonstrated exceptionally high (80.4 to 81.3%) amino acid identities to that of human/civet SARSr-CoVs, compared to SARSr-BatCoVs from other horseshoe bats (23.2 to 37.3%). Potential recombination events were identified around ORF8 between SARSr-Rf-BatCoVs and SARSr-Rs-BatCoVs, leading to the generation of civet SARSr-CoVs. The expression of ORF8 subgenomic mRNA suggested that the ORF8 protein may be functional in SARSr-Rf-BatCoVs. The high Ka/Ks ratio among human SARS-CoVs compared to that among SARSr-BatCoVs supported that ORF8 is under strong positive selection during animal-to-human transmission. Molecular clock analysis using ORF1ab showed that SARSr-Rf-BatCoV YNLF_31C and YNLF_34C diverged from civet/human SARSr-CoVs in approximately 1990. SARS

  20. Automated rectification and geocoding of SAR imagery

    NASA Technical Reports Server (NTRS)

    Kwok, R.; Curlander, J. C.

    1987-01-01

    An automated post-processing system has been developed for rectification and geocoding of SAR (Synthetic Aperture Radar) imagery. The system uses as input a raw uncorrected image from the operational SAR correlator, and produces as a standard output a rectified and geocoded product. The accurate geolocation of SAR image pixels is provided by a spatial transformation model which maps the slant range-azimuth SAR image pixels into their location on a prespecified map grid. This model predicts the geodetic location of each pixel by utilizing: the sensor platform position; a geoid model; the parameters of the data collection system and the processing parameters used in the SAR correlator. Based on their geodetic locations, the pixels are mapped by using the desired cartographic projection equations. This rectification and geocoding technique has been tested with Seasat and SIR-B images. The test results demonstrate absolute location uncertainty of less than 50 m and relative distortion (scale factor and skew) of less than 0.1 percent relative to local variations from the assumed geoid.

  1. ICAO's anti-SARS airport activities.

    PubMed

    Finkelstein, Silvio; Curdt-Christiansen, Claus M

    2003-11-01

    To prevent SARS from spreading through air travel and in order to rebuild the confidence of the traveling public in the safety of air travel, ICAO has set up an "Anti-SARS Airport Evaluation Project." The first phase of this project was to develop a set of protective measures for international airports in affected areas to adopt and implement and then to send out, on the request of Contracting States, a team of inspectors to evaluate and assess airports and issue a "statement of evaluation" that the airport inspected complies with the ICAO anti-SARS protective measures. In cooperation with the World Health Organization (WHO), the first part of phase 1 was completed in early June this year, and the second part of phase 1 followed soon after. By mid-July, five international airports in Southeast Asia had been inspected and found to be in full compliance with the ICAO anti-SARS protective measures. The success of this ICAO project is believed to have contributed significantly to the recovery of international air travel and related industries now taking place. Phase 2 of the project is now being developed. It is aimed at preventing a resurgence of SARS, but it also contains elements to make the methodology developed applicable to future outbreaks of any other communicable disease in which the mode of transmission could involve aviation and/or the need to prevent the spread of the disease by air travel.

  2. A comparative evaluation of SAR and SLAR

    SciTech Connect

    Mastin, G.A.; Manson, J.J.; Bradley, J.D.; Axline, R.M.; Hover, G.L.

    1993-11-01

    Synthetic aperture radar (SAR) was evaluated as a potential technological improvement over the Coast Guard`s existing side-looking airborne radar (SLAR) for oil-spill surveillance applications. The US Coast Guard Research and Development Center (R&D Center), Environmental Branch, sponsored a joint experiment including the US Coast Guard, Sandia National Laboratories, and the Naval Oceanographic and Atmospheric Administration (NOAA), Hazardous Materials Division. Radar imaging missions were flown on six days over the coastal waters off Santa Barbara, CA, where there are constant natural seeps of oil. Both the Coast Guard SLAR and the Sandia National Laboratories SAR were employed to acquire simultaneous images of oil slicks and other natural sea surface features that impact oil-spill interpretation. Surface truth and other environmental data were also recorded during the experiment. The experiment data were processed at Sandia National Laboratories and delivered to the R&D Center on a computer workstation for analysis by experiment participants. Issues such as optimal spatial resolution, single-look vs. multi-look SAR imaging, and the utility of SAR for oil-spill analysis were addressed. Finally, conceptual design requirements for a possible future Coast Guard SAR were outlined and evaluated.

  3. SARS revisited: managing "outbreaks" with "communications".

    PubMed

    Menon, K U

    2006-05-01

    "Risk communications" has acquired some importance in the wake of our experience of SARS. Handled well, it helps to build mutual respect between a government or an organisation and the target groups with which it is communicating. It helps nurture public trust and confidence in getting over the crisis. The World Health Organization (WHO) has also come to recognise its importance after SARS and organised the first Expert Consultation on Outbreak Communications conference in Singapore in September 2004. This article assesses the context and the key features which worked to Singapore's advantage. Looking at the data now widely available on the Internet of the experience of SARS-infected countries like China, Taiwan, Canada, the article identifies the key areas of strategic communications in which Singapore fared particularly well. Another issue discussed is whether Singapore's experience has universal applicability or whether it is limited because of Singapore's unique cultural, historical and geographical circumstances. Finally, the article also looks at some of the post-SARS enhancements that have been put in place following the lessons learnt from SARS and the need to confront new infectious outbreaks like avian flu. PMID:16830005

  4. An improved MIMO-SAR simulator strategy with ray tracing

    NASA Astrophysics Data System (ADS)

    Xiang, Xingyu; Mo, Zijian; Wang, Zhonghai; Chen, Genshe; Pham, Khanh; Blasch, Erik

    2016-05-01

    High resolution and wide-swath imaging can be obtained by Multiple-Input Multiple-Output (MIMO) synthetic aperture radar (SAR) with the state of the art technologies. The time division multiple access (TDMA) MIMO SAR mimics the motion of the antenna of SAR systems by switching the array channels to transmit the radar signals at different time slots. In this paper, we develop a simulation tool with ray tracing techniques to retrieve high resolution and accurate SAR images for development of MIMO SAR imaging methods. Without loss of generality, in the proposed simulator, we apply a TDMA MIMO SAR system with 13 transmitting antennas and 8 receiving antennas, where all transmitting antennas share a single transmitter and the receiving antennas share a single receiver. By comparing with the normal simulation MIMO SAR strategies, the simulation image using ray tracing results validate that the proposed method provides more accurate and higher resolution SAR images.

  5. Statistical Approach To Determination Of Texture In SAR

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Kwok, Ronald

    1993-01-01

    Paper presents statistical approach to analysis of texture in synthetic-aperture-radar (SAR) images. Objective: to extract intrinsic spatial variability of distributed target from overall spatial variability of SAR image.

  6. Characterizing hydrologic changes of Great Dismal Swamp using SAR/InSAR technology

    NASA Astrophysics Data System (ADS)

    Kim, J. W.; Lu, Z.; Zhu, Z.

    2015-12-01

    Great Dismal Swamp is one of the largest, northernmost peatlands on the Atlantic Coastal Plain, and the swamp is underlain by a thick water-logged organic soil layer (peat) made up of dead and decaying plant material. The peatlands play a role as the sink of large amount of soil organic carbon and methane. However, the disturbance of the peatland negatively impacted the ecosystem and contributed to the climate change caused by the released greenhouse gas. Our SAR/InSAR methods observed the hydrologic changes in the peatlands, which is a key factor to conserve the wetland, through several methods. First, we compared averaged SAR intensity from C- and L-band SAR sensors with groundwater level changes, and deduced a linear relationship between the SAR backscattering intensity and the groundwater level change. Second, we extracted the inundated area during wet season from InSAR coherence. Third, we measured the relative water level changes in the inundated area using the interferometric phases. Finally, we estimated the groundwater level changes corresponding to the soil moisture changes from time-series InSAR method. Our results can provide the unique opportunity to understand the occurring hydrologic and vegetation changes in the Great Dismal Swamp.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  8. Absolute radiometric calibration of the CCRS SAR

    NASA Astrophysics Data System (ADS)

    Ulander, Lars M. H.; Hawkins, Robert K.; Livingstone, Charles E.; Lukowski, Tom I.

    1991-11-01

    Determining the radar scattering coefficients from SAR (synthetic aperture radar) image data requires absolute radiometric calibration of the SAR system. The authors describe an internal calibration methodology for the airborne Canada Centre for Remote Sensing (CCRS) SAR system, based on radar theory, a detailed model of the radar system, and measurements of system parameters. The methodology is verified by analyzing external calibration data acquired over a 6-month period in 1988 by the C-band radar using HH polarization. The results indicate that the overall error is +/- 0.8 dB (1-sigma) for incidence angles +/- 20 deg from antenna boresight. The dominant error contributions are due to the antenna radome and uncertainties in the elevation angle relative to the antenna boresight.

  9. Calibration of a polarimetric imaging SAR

    NASA Technical Reports Server (NTRS)

    Sarabandi, K.; Pierce, L. E.; Ulaby, F. T.

    1991-01-01

    Calibration of polarimetric imaging Synthetic Aperture Radars (SAR's) using point calibration targets is discussed. The four-port network calibration technique is used to describe the radar error model. The polarimetric ambiguity function of the SAR is then found using a single point target, namely a trihedral corner reflector. Based on this, an estimate for the backscattering coefficient of the terrain is found by a deconvolution process. A radar image taken by the JPL Airborne SAR (AIRSAR) is used for verification of the deconvolution calibration method. The calibrated responses of point targets in the image are compared both with theory and the POLCAL technique. Also, response of a distributed target are compared using the deconvolution and POLCAL techniques.

  10. Block adaptive quantization of Magellan SAR data

    NASA Technical Reports Server (NTRS)

    Kwok, Ronald; Johnson, William T. K.

    1989-01-01

    A report is presented on a data compression scheme that will be used to reduce the SAR data rate on the NASA Magellan mission to Venus. The spacecraft has only one scientific instrument, a radar system for imaging the surface, for altimetric profiling of the planet topography, and for measuring radiation from the planet surface. A straightforward implementation of the scientific requirements of the mission results in a data rate higher than can be accommodated by the available system bandwidth. A data-rate-reduction scheme which includes operation of the radar in burst mode and block-adaptive quantization of the SAR data is selected to satisfy the scientific requirements. Descriptions of the quantization scheme and its hardware implementation are given. Burst-mode SAR operation is also briefly discussed.

  11. The Radarsat SAR multi-beam antenna

    NASA Astrophysics Data System (ADS)

    Martins-Camelo, L.; Cooper, R. T.; Zimcik, D. G.

    1984-10-01

    Radarsat, the Canadian radar imaging satellite, will have a Synthetic Aperture Radar (SAR) antenna as one of its sensors. The requirements on the performance of the SAR antenna are such as to make it a complex system. Radarsat is required to have some unique characteristics which present some new challenges to the antenna designers. The requirements for switchability among 4 shaped beams and high power of transmit operation are major design constraints which strongly impact on the antenna complexity, weight, and cost. A trade-off study was carried out to select the preferred antenna type for the Radarsat SAR function. The antenna types analyzed were planar-array and array-fed reflector. A set of comparison criteria was developed. The antenna concepts studied were then compared against these criteria, and a final decision was reached.

  12. New approaches in interferometric SAR data processing

    NASA Technical Reports Server (NTRS)

    Lin, Qian; Vesecky, John F.; Zebker, Howard A.

    1992-01-01

    It is well established that interferometric synthetic aperture radar (SAR) images can be inverted to perform surface elevation mapping. Among the factors critical to the mapping accuracy are registration of the interfering SAR images and phase unwrapping. A novel registration algorithm is presented that determines the registration parameters through optimization. A new figure of merit is proposed that evaluates the registration result during the optimization. The phase unwrapping problem is approached through a new method involving fringe line detection. The algorithms are tested with two SEASAT SAR images of terrain near Yellowstone National Park. These images were collected on Seasat orbits 1334 and 1420, which were very close together in space, i.e., less than 100 m. The resultant elevation map is compared with the USGS digital terrain elevation model.

  13. Linear Approximation SAR Azimuth Processing Study

    NASA Technical Reports Server (NTRS)

    Lindquist, R. B.; Masnaghetti, R. K.; Belland, E.; Hance, H. V.; Weis, W. G.

    1979-01-01

    A segmented linear approximation of the quadratic phase function that is used to focus the synthetic antenna of a SAR was studied. Ideal focusing, using a quadratic varying phase focusing function during the time radar target histories are gathered, requires a large number of complex multiplications. These can be largely eliminated by using linear approximation techniques. The result is a reduced processor size and chip count relative to ideally focussed processing and a correspondingly increased feasibility for spaceworthy implementation. A preliminary design and sizing for a spaceworthy linear approximation SAR azimuth processor meeting requirements similar to those of the SEASAT-A SAR was developed. The study resulted in a design with approximately 1500 IC's, 1.2 cubic feet of volume, and 350 watts of power for a single look, 4000 range cell azimuth processor with 25 meters resolution.

  14. Stop outbreak of SARS with infrared cameras

    NASA Astrophysics Data System (ADS)

    Wu, Yigang M.

    2004-04-01

    SARS (Severe Acute Respiratory Syndrome, commonly known as Atypical Pneumonia in mainland China) caused 8422 people affected and resulting in 918 deaths worldwide in half year. This disease can be transmitted by respiratory droplets or by contact with a patient's respiratory secretions. This means it can be spread out very rapidly through the public transportations by the travelers with the syndrome. The challenge was to stop the SARS carriers traveling around by trains, airplanes, coaches and etc. It is impractical with traditional oral thermometers or spot infrared thermometers to screen the tens of travelers with elevated body temperature from thousands of normal travelers in hours. The thermal imager with temperature measurement function is a logical choice for this special application although there are some limitations and drawbacks. This paper discusses the real SARS applications of industrial infrared cameras in China from April to July 2003.

  15. Probing Mechanical Properties of Rock with InSAR

    NASA Astrophysics Data System (ADS)

    Jónsson, S.

    2012-04-01

    Interferometric Synthetic Aperture Radar (InSAR) observations from satellites have revolutionized our crustal deformation measurement capabilities with its high spatial resolution, global coverage, and low cost. The high spatial resolution (typically 5-20 m) allows us to map many small-scale surface deformation phenomena in great detail. These include surface faulting, fissuring, fault creep, and other strain localization phenomena. Another advantage of the small-scale deformation mapping is that it can provide information about mechanical properties of near-surface rocks. Several studies have already been published on using InSAR to probe material properties of rock. Strain localizations at fault zones have been observed in co-seismic deformation fields near to large earthquakes and interpreted as expressions of weak fault zone materials that are a factor of two more compliant than the surrounding unbroken rock [Fialko et al., 2002]. Peltzer et al. [1999] argued that asymmetries in coseismic deformation patterns observed by InSAR showed evidence for non-linear elasticity, i.e. that the elastic moduli of shallow crustal material are different for compression and extension, due to small-scale cracks in the medium. This interpretation was later disputed by Funning et al. [2007], who provided an alternative explanation for observed deformation pattern based on along-strike variations in fault geometry and slip. In addition, observations and modeling of poro-elastic rebound after earthquakes have provided information about the difference in undrained and drained Poisson's ratio values of the near-surface rocks [Peltzer et al., 1996; Jónsson et al., 2003]. More recently we have used InSAR observations to put bounds on the tensional bulk strength of surface rocks. A dyke intrusion that took place in western Saudi Arabia in 2009 caused many moderate-sized earthquakes and extensive surface faulting. InSAR data of the area show that large-scale (40 km x 40 km) east

  16. SAR imagery using chaotic carrier frequency agility pulses

    NASA Astrophysics Data System (ADS)

    Xu, Xiaojian; Feng, Xiangzhi

    2011-06-01

    Synthetic aperture radar (SAR) systems are getting more and more applications in both civilian and military remote sensing missions. With the increasing deployment of electronic countermeasures (ECM) on modern battlefields, SAR encounters more and more interference jamming signals. The ECM jamming signals cause the SAR system to receive and process erroneous information which results in severe degradations in the output SAR images and/or formation of phony images of nonexistent targets. As a consequence, development of the electronic counter-countermeasures (ECCM) capability becomes one of the key problems in SAR system design. This paper develops radar signaling strategies and algorithms that enhance the ability of synthetic aperture radar to image targets under conditions of electronic jamming. The concept of SAR using chaotic carrier frequency agility pulses (CCFAP-SAR) is first proposed. Then the imaging procedure for CCFAP-SAR is discussed in detail. The ECCM performance of CCFAP-SAR for both depressive noise jamming and deceptive repeat jamming is analyzed. The impact of the carrier frequency agility range on the image quality of CCFAP-SAR is also studied. Simulation results demonstrate that, with adequate agility range of the carrier frequency, the proposed CCFAP-SAR performs as well as conventional radar with linear frequency modulation (LFM) waveform in image quality and slightly better in anti-noise depressive jamming; while performs very well in anti-deception jamming which cannot be rejected by LFM-SAR.

  17. Severe Acute Respiratory Syndrome (SARS) Prevention in Taiwan

    ERIC Educational Resources Information Center

    Liu, Hsueh-Erh

    2004-01-01

    Severe Acute Respiratory Syndrome (SARS) is a newly identified respiratory disease that threatened Taiwan between April 14 and July 5, 2003. Chang Gung University experienced various SARS-related episodes, such as the postponement of classes for 7 days, the reporting of probable SARS cases, and the isolation of students under Level A and B…

  18. Progress Toward Demonstrating SAR Monitoring of Chinese Seas

    NASA Astrophysics Data System (ADS)

    Huang, Weigen; Johannessen, Johnny; Alpers, Werner; Yang, Jingsong

    2010-12-01

    "Demonstrating SAR monitoring of Chinese seas" is a project of the ESA-MOST Dragon 2 program. This paper presents the progress of the project. Retrieval algorithms for SAR monitoring of sea surface currents, oceanic internal waves, sea surface winds, oil spills and ships have been advanced. SAR monitoring of Chinese seas in near-real-time is now in demonstration phase.

  19. First Results from an Airborne Ka-Band SAR Using SweepSAR and Digital Beamforming

    NASA Technical Reports Server (NTRS)

    Sadowy, Gregory A.; Ghaemi, Hirad; Hensley, Scott C.

    2012-01-01

    SweepSAR is a wide-swath synthetic aperture radar technique that is being studied for application on the future Earth science radar missions. This paper describes the design of an airborne radar demonstration that simulates an 11-m L-band (1.2-1.3 GHz) reflector geometry at Ka-band (35.6 GHz) using a 40-cm reflector. The Ka-band SweepSAR Demonstration system was flown on the NASA DC-8 airborne laboratory and used to study engineering performance trades and array calibration for SweepSAR configurations. We present an instrument and experiment overview, instrument calibration and first results.

  20. Isotherms for Water Adsorption on Molecular Sieve 3A: Influence of Cation Composition

    SciTech Connect

    Lin, Ronghong; Ladshaw, Austin; Nan, Yue; Liu, Jiuxu; Yiacoumi, Sotira; Tsouris, Costas; DePaoli, David W.; Tavlarides, Lawrence L.

    2015-06-16

    This study is part of our continuing efforts to address engineering issues related to the removal of tritiated water from off-gases produced in used nuclear fuel reprocessing facilities. In the current study, adsorption equilibrium of water on molecular sieve 3A beads was investigated. Adsorption isotherms for water on the UOP molecular sieve 3A were measured by a continuous-flow adsorption system at 298, 313, 333, and 353 K. Experimental data collected were analyzed by the Generalized Statistical Thermodynamic Adsorption (GSTA) isotherm model. The K+/Na+ molar ratio of this particular type of molecular sieve 3A was ~4:6. Our results showed that the GSTA isotherm model worked very well to describe the equilibrium behavior of water adsorption on molecular sieve 3A. The optimum number of parameters for the current experimental data was determined to be a set of four equilibrium parameters. This result suggests that the adsorbent crystals contain four energetically distinct adsorption sites. In addition, it was found that water adsorption on molecular sieve 3A follows a three-stage adsorption process. This three-stage adsorption process confirmed different water adsorption sites in molecular sieve crystals. In addition, the second adsorption stage is significantly affected by the K+/Na+ molar ratio. In this stage, the equilibrium adsorption capacity at a given water vapor pressure increases as the K+/Na+ molar ratio increases.

  1. Isotherms for Water Adsorption on Molecular Sieve 3A: Influence of Cation Composition

    DOE PAGES

    Lin, Ronghong; Ladshaw, Austin; Nan, Yue; Liu, Jiuxu; Yiacoumi, Sotira; Tsouris, Costas; DePaoli, David W.; Tavlarides, Lawrence L.

    2015-06-16

    This study is part of our continuing efforts to address engineering issues related to the removal of tritiated water from off-gases produced in used nuclear fuel reprocessing facilities. In the current study, adsorption equilibrium of water on molecular sieve 3A beads was investigated. Adsorption isotherms for water on the UOP molecular sieve 3A were measured by a continuous-flow adsorption system at 298, 313, 333, and 353 K. Experimental data collected were analyzed by the Generalized Statistical Thermodynamic Adsorption (GSTA) isotherm model. The K+/Na+ molar ratio of this particular type of molecular sieve 3A was ~4:6. Our results showed that themore » GSTA isotherm model worked very well to describe the equilibrium behavior of water adsorption on molecular sieve 3A. The optimum number of parameters for the current experimental data was determined to be a set of four equilibrium parameters. This result suggests that the adsorbent crystals contain four energetically distinct adsorption sites. In addition, it was found that water adsorption on molecular sieve 3A follows a three-stage adsorption process. This three-stage adsorption process confirmed different water adsorption sites in molecular sieve crystals. In addition, the second adsorption stage is significantly affected by the K+/Na+ molar ratio. In this stage, the equilibrium adsorption capacity at a given water vapor pressure increases as the K+/Na+ molar ratio increases.« less

  2. Efficacy of various disinfectants against SARS coronavirus.

    PubMed

    Rabenau, H F; Kampf, G; Cinatl, J; Doerr, H W

    2005-10-01

    The recent severe acute respiratory syndrome (SARS) epidemic in Asia and Northern America led to broad use of various types of disinfectant in order to control the public spread of the highly contagious virus. However, only limited data were available to demonstrate their efficacy against SARS coronavirus (SARS-CoV). We therefore investigated eight disinfectants for their activity against SARS-CoV according to prEN 14476. Four hand rubs were tested at 30s (Sterillium, based on 45% iso-propanol, 30% n-propanol and 0.2% mecetronium etilsulphate; Sterillium Rub, based on 80% ethanol; Sterillium Gel, based on 85% ethanol; Sterillium Virugard, based on 95% ethanol). Three surface disinfectants were investigated at 0.5% for 30 min and 60 min (Mikrobac forte, based on benzalkonium chloride and laurylamine; Kohrsolin FF, based on benzalkonium chloride, glutaraldehyde and didecyldimonium chloride; Dismozon pur, based on magnesium monoperphthalate), and one instrument disinfectant was investigated at 4% for 15 min, 3% for 30 min and 2% for 60 min [Korsolex basic, based on glutaraldehyde and (ethylenedioxy)dimethanol]. Three types of organic load were used: 0.3% albumin, 10% fetal calf serum, and 0.3% albumin with 0.3% sheep erythrocytes. Virus titres were determined by a quantitative test (endpoint titration) in 96-well microtitre plates. With all tested preparations, SARS-CoV was inactivated to below the limit of detection (reduction factor mostly > or =4), regardless of the type of organic load. In summary, SARS-CoV can be inactivated quite easily with many commonly used disinfectants.

  3. SAR measurement in MRI: an improved method

    NASA Astrophysics Data System (ADS)

    Romano, Rocco; Acernese, Fausto; Indovina, Pietro Luigi; Barone, Fabrizio

    2009-03-01

    During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2- 33). The phase transition method is a new method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement. Furthermore, in this method, it is possible to show that all deposited SAR power can be considered acquired and measured.

  4. CCD architecture for spacecraft SAR image processing

    NASA Technical Reports Server (NTRS)

    Arens, W. E.

    1977-01-01

    A real-time synthetic aperture radar (SAR) image processing architecture amenable to future on-board spacecraft applications is currently under development. Using state-of-the-art charge-coupled device (CCD) technology, low cost and power are inherent features. Other characteristics include the ability to reprogram correlation reference functions, correct for range migration, and compensate for antenna beam pointing errors on the spacecraft in real time. The first spaceborne demonstration is scheduled to be flown as an experiment on a 1982 Shuttle imaging radar mission (SIR-B). This paper describes the architecture and implementation characteristics of this initial spaceborne CCD SAR image processor.

  5. Estimating IMU heading error from SAR images.

    SciTech Connect

    Doerry, Armin Walter

    2009-03-01

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

  6. Unsupervised Segmentation Of Polarimetric SAR Data

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Dubois, Pascale; Van Zyl, Jakob; Kwok, Ronald; Chellappa, Rama

    1994-01-01

    Method of unsupervised segmentation of polarimetric synthetic-aperture-radar (SAR) image data into classes involves selection of classes on basis of multidimensional fuzzy clustering of logarithms of parameters of polarimetric covariance matrix. Data in each class represent parts of image wherein polarimetric SAR backscattering characteristics of terrain regarded as homogeneous. Desirable to have each class represent type of terrain, sea ice, or ocean surface distinguishable from other types via backscattering characteristics. Unsupervised classification does not require training areas, is nearly automated computerized process, and provides nonsubjective selection of image classes naturally well separated by radar.

  7. Single-cell genomics reveal low recombination frequencies in freshwater bacteria of the SAR11 clade

    PubMed Central

    2013-01-01

    Background The SAR11 group of Alphaproteobacteria is highly abundant in the oceans. It contains a recently diverged freshwater clade, which offers the opportunity to compare adaptations to salt- and freshwaters in a monophyletic bacterial group. However, there are no cultivated members of the freshwater SAR11 group and no genomes have been sequenced yet. Results We isolated ten single SAR11 cells from three freshwater lakes and sequenced and assembled their genomes. A phylogeny based on 57 proteins indicates that the cells are organized into distinct microclusters. We show that the freshwater genomes have evolved primarily by the accumulation of nucleotide substitutions and that they have among the lowest ratio of recombination to mutation estimated for bacteria. In contrast, members of the marine SAR11 clade have one of the highest ratios. Additional metagenome reads from six lakes confirm low recombination frequencies for the genome overall and reveal lake-specific variations in microcluster abundances. We identify hypervariable regions with gene contents broadly similar to those in the hypervariable regions of the marine isolates, containing genes putatively coding for cell surface molecules. Conclusions We conclude that recombination rates differ dramatically in phylogenetic sister groups of the SAR11 clade adapted to freshwater and marine ecosystems. The results suggest that the transition from marine to freshwater systems has purged diversity and resulted in reduced opportunities for recombination with divergent members of the clade. The low recombination frequencies of the LD12 clade resemble the low genetic divergence of host-restricted pathogens that have recently shifted to a new host. PMID:24286338

  8. A sea ice concentration estimation algorithm utilizing radiometer and SAR data

    NASA Astrophysics Data System (ADS)

    Karvonen, J.

    2014-04-01

    We have studied the possibility of combining the high-resolution SAR segmentation and ice concentration estimated by radiometer brightness temperatures. Here we present an algorithm for mapping a radiometer-based concentration value for each SAR segment. The concentrations are estimated by a MLP neural network which has the AMSR-2 radiometer polarization ratios and gradient ratios of four radiometer channels as its inputs. The results have been compared numerically to the gridded FMI ice chart concentrations and high-resolution AMSR-2 ASI algorithm concentrations provided by University of Hamburg and also visually to the AMSR-2 bootstrap algorithm concentrations, which are given in much coarser resolution. The results when compared to FMI ice charts were very promising.

  9. Influence of Ca2+ on tetracycline adsorption on montmorillonite.

    PubMed

    Parolo, M Eugenia; Avena, Marcelo J; Pettinari, Gisela R; Baschini, Miria T

    2012-02-15

    The adsorption of tetracycline (TC) on montmorillonite was studied as a function of pH and Ca(2+) concentration using a batch technique complemented with X-ray diffraction and transmission electron microscopy. In the absence of Ca(2+), TC adsorption was high at low pH and decreased as the pH increased. In the presence of Ca(2+), at least two different adsorption processes took place in the studied systems, i.e., cation exchange and Ca-bridging. Cation exchange was the prevailing process at pH<5, and thus, TC adsorption decreased by increasing total Ca(2+) concentration. On the contrary, Ca-bridging was the prevailing process at pH>5, and thus, TC adsorption increased by increasing Ca(2+) concentration. The pH 5 represents an isoadsorption pH where both adsorption processes compensate each other. TC adsorption became independent of Ca(2+) concentration at this pH. For TC adsorption on Ca(2+)-montmorillonite in 0.01 M NaCl experiments, the ratio adsorbed TC/retained Ca(2+) was close to 1 in the pH range of 5-9, indicating an important participation of Ca(2+) in the binding of TC to montmorillonite. X-ray diffraction and transmission electron microscopy showed that TC adsorption induced intercalation between montmorillonite layers forming a multiphase system with stacking of layers with and without intercalated TC. PMID:22189389

  10. The "Myth" of the Minimum SAR Antenna Area Constraint

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Johnson, W. T. K.; Huneycutt, B.; Jordan, R.; Hensley, S.; Siqueira, P.; Curlander, J.

    1998-01-01

    A design constraint traceable ot the early days of spaceborne Synthetic Aperture Radar (SAR) is known as the minimum antenna area constraint for SAR. In this paper, it is confirmed that this constraint strictly applies only to the case where both the best possible resolution and the widest possible swath are the design goals. SAR antennas with area smaller than the constraint allows are shown to be possible, have been used on spaceborne SAR missions in the past, and should permit further, lower-cost SAR mission in the future.

  11. A New Design of Metamaterials for SAR Reduction

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    The purpose of this paper is to calculate the reduction of specific absorption rate (SAR) with a new design of square metamaterials (SMMs). The finite-difference time-domain (FDTD) method with lossy-Drude model is adopted in this analysis. The method of SAR reduction is discussed and the effects of location, distance, and size of metamaterials are analyzed. SMMs have achieved a 53.06% reduction of the initial SAR value for the case of 10 gm SAR. These results put forward a guideline to select various types of metamaterials with the maximum SAR reducing effect for a cellular phone.

  12. Hybrid adsorptive membrane reactor

    NASA Technical Reports Server (NTRS)

    Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

    2011-01-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  13. Hybrid adsorptive membrane reactor

    DOEpatents

    Tsotsis, Theodore T.; Sahimi, Muhammad; Fayyaz-Najafi, Babak; Harale, Aadesh; Park, Byoung-Gi; Liu, Paul K. T.

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  14. Compressed Sensing for Millimeter-wave Ground Based SAR/ISAR Imaging

    NASA Astrophysics Data System (ADS)

    Yiğit, Enes

    2014-11-01

    Millimeter-wave (MMW) ground based (GB) synthetic aperture radar (SAR) and inverse SAR (ISAR) imaging are the powerful tools for the detection of foreign object debris (FOD) and concealed objects that requires wide bandwidths and highly frequent samplings in both slow-time and fast-time domains according to Shannon/Nyquist sampling theorem. However, thanks to the compressive sensing (CS) theory GB-SAR/ISAR data can be reconstructed by much fewer random samples than the Nyquist rate. In this paper, the impact of both random frequency sampling and random spatial domain data collection of a SAR/ISAR sensor on reconstruction quality of a scene of interest was studied. To investigate the feasibility of using proposed CS framework, different experiments for various FOD-like and concealed object-like targets were carried out at the Ka and W band frequencies of the MMW. The robustness and effectiveness of the recommend CS-based reconstruction configurations were verified through a comparison among each other by using integrated side lobe ratios (ISLR) of the images.

  15. Research on data fusion for monitoring ground subsidence using InSAR

    NASA Astrophysics Data System (ADS)

    Ma, Jing; Zhang, Qin; Liu, Xianglei; Zhao, Chaoying

    2008-12-01

    Interferometric Synthetic Aperture Radar (InSAR) magtitude map, extracted from Differential- Interferometric Syntheric Aperture Radar (D-InSAR) technology, has a low-resolution, so it has a certain limitation to the explanation and analysis of subsiding area. In order to solve the problem of lacking enough spatial information of D-InSAR image, in this essay we take a data fusion between D-InSAR image and high resolution Remote Sensing (RS) image, obtaining an image containing subsiding information and high-resolution spatial information. This paper mainly focuses on the study of a Mag-Phase algorithm (MPH) algorithm and other fusion algorithms including Hue-Intensity-Saturation (HIS) transformation, Principal Component Analysis (PCA) transformation, Product fusion, Ratio fusion, Wavelet fusion for magtitude map and deformation map, and we take the deformation map and panchromatic (PAN) image of Enhanced Thematic Mapper + (ETM+) (magtitude map) of Xi'an area as an example to do data fusion according to the algorithms above. At last, a comprehensive evaluation and analysis for fusion images is made with subjective and objective evaluation criteria, and a conclusion that MPH fusion algorithm is better than others is also obtained.

  16. Analysis of Scattering Components from Fully Polarimetric SAR Images for Improving Accuracies of Urban Density Estimation

    NASA Astrophysics Data System (ADS)

    Susaki, J.

    2016-06-01

    In this paper, we analyze probability density functions (PDFs) of scatterings derived from fully polarimetric synthetic aperture radar (SAR) images for improving the accuracies of estimated urban density. We have reported a method for estimating urban density that uses an index Tv+c obtained by normalizing the sum of volume and helix scatterings Pv+c. Validation results showed that estimated urban densities have a high correlation with building-to-land ratios (Kajimoto and Susaki, 2013b; Susaki et al., 2014). While the method is found to be effective for estimating urban density, it is not clear why Tv+c is more effective than indices derived from other scatterings, such as surface or double-bounce scatterings, observed in urban areas. In this research, we focus on PDFs of scatterings derived from fully polarimetric SAR images in terms of scattering normalization. First, we introduce a theoretical PDF that assumes that image pixels have scatterers showing random backscattering. We then generate PDFs of scatterings derived from observations of concrete blocks with different orientation angles, and from a satellite-based fully polarimetric SAR image. The analysis of the PDFs and the derived statistics reveals that the curves of the PDFs of Pv+c are the most similar to the normal distribution among all the scatterings derived from fully polarimetric SAR images. It was found that Tv+c works most effectively because of its similarity to the normal distribution.

  17. Adsorption in sparse networks. 1: Cylinder model

    SciTech Connect

    Scherer, G.W.

    1998-06-15

    Materials with very low density, such as aerogels, are networks with polymers or chains of particles joined at nodes, where the spacing of the nodes is large compared to the thickness of the chains. In such a material, most of the solid surface has positive curvature, so condensation of an adsorbate is more difficult than condensation in a body containing cavities whose surfaces have negative curvature. A model is presented in which the network is represented by straight cylinders joined at nodes with coordination numbers 4, 6, or 12. The shape of the adsorbate/adsorptive interface is obtained for each network by minimizing its surface area. The adsorption behavior is found to depend on the ratio of the node separation, l, to the radius of the cylinders, a: if l/a exceeds a critical value (which depends on the coordination of the node), then the curvature of the adsorbate/adsorptive interface approaches zero while the adsorbate occupies a small fraction of the pore volume; if l/a is less than the critical value, then condensation occurs. Even in the latter case, interpretation of the adsorption isotherm in terms of cylindrical pores (as in the BJH model) yields apparent pore sizes much greater than the actual spacing of the nodes. In a companion paper, this model is applied to silica aerogels and found to give a good fit to both the adsorption and desorption curves with a single distribution of node spacings.

  18. A 1 V 186-μW 50-MS/s 10-bit subrange SAR ADC in 130-nm CMOS process

    NASA Astrophysics Data System (ADS)

    Mingyuan, Yu; Ting, Li; Jiaqi, Yang; Shuangshuang, Zhang; Fujiang, Lin; Lin, He

    2016-07-01

    This paper presents a 10-bit 50-MS/s subrange successive-approximation register (SAR) analog-to-digital converter (ADC) composed of a 4-bit SAR coarse ADC and a 6-bit SAR fine ADC. In the coarse ADC, multi-comparator SAR architecture is used to reduce the digital logic propagation delay, and a traditional asynchronous SAR ADC with monotonic switching method is used as the fine ADC. With that combination, power dissipation also can be much reduced. Meanwhile, a modified SAR control logic is adopted in the fine ADC to speed up the conversion and other techniques, such as splitting capacitors array, are borrowed to reduce the power consumption. Fabricated with 1P8M 130-nm CMOS technology, the proposed SAR ADC achieves 51.6-dB signal to noise and distortion ratio (SNDR) and consumes 186 μW at 50 MS/s with a 1-V supply, resulting in a figure of merit (FOM) of 12 fJ/conversion-step. The core area is only 0.045 mm2. Project supported by the National Natural Science Foundation of China (Nos. 61204033, 61331015), the Fundamental Research Funds for the Central Universities (No. WK2100230015), and the Funds of Science and Technology on Analog Integrated Circuit Laboratory (No. 9140C090111150C09041).

  19. Support Detection for SAR Tomographic Reconstructions from Compressive Measurements

    PubMed Central

    Budillon, Alessandra; Schirinzi, Gilda

    2015-01-01

    The problem of detecting and locating multiple scatterers in multibaseline Synthetic Aperture Radar (SAR) tomography, starting from compressive measurements and applying support detection techniques, is addressed. Different approaches based on the detection of the support set of the unknown sparse vector, that is, of the position of the nonzero elements in the unknown sparse vector, are analyzed. Support detection techniques have already proved to allow a reduction in the number of measurements required for obtaining a reliable solution. In this paper, a support detection method, based on a Generalized Likelihood Ratio Test (Sup-GLRT), is proposed and compared with the SequOMP method, in terms of probability of detection achievable with a given probability of false alarm and for different numbers of measurements. PMID:26495434

  20. Ambiguity noise analysis of a SAR system

    NASA Astrophysics Data System (ADS)

    Tian, Haishan; Chang, Wenge; Li, Xiangyang

    2015-12-01

    The presence of range and azimuth (or Doppler) ambiguities in synthetic aperture radars (SARs) is well known. The ambiguity noise is related to the antenna pattern and the value of pulse repetition frequency (PRF). Because a new frequency modulated continuous wave (FMCW) SAR has the characters of low cost and small size, and the capacity of real-time signal processing, the antenna will likely vibrate or deform due to a lack of the stabilized platform. And the value of PRF cannot be much high because of the high computation burden for the real-time processing. The aim of this study is to access and improve the performance of a new FMCW SAR system based on the ambiguity noise. First, the quantitative analysis of the system's ambiguity noise level is performed; an antenna with low sidelobes is designed. The conclusion is that the range ambiguity noise is small; the azimuth ambiguity noise is somewhat increased, however, it is sufficiently small to have marginal influence on the image quality. Finally, the ambiguity noise level is measured using the imaging data from a Ku-band FMCW SAR. The results of this study show that the measured noise level coincides with the theoretical noise level.

  1. Epidemic Models for SARS and Measles

    ERIC Educational Resources Information Center

    Rozema, Edward

    2007-01-01

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

  2. Acousto-Optical/Electronic Processor For SAR

    NASA Technical Reports Server (NTRS)

    Bicknell, T. J.; Farr, W. H.

    1992-01-01

    Lightweight, compact, low-power apparatus processes synthetic-aperture-radar (SAR) returns in real time, providing imagery aboard moving aircraft or spacecraft platform. Processor includes optical and electronic subsystems that, together, resolve range and azimuth coordinates of radar targets by combination of spatial and temporal integrations.

  3. SAR Image Despeckling Via Structural Sparse Representation

    NASA Astrophysics Data System (ADS)

    Lu, Ting; Li, Shutao; Fang, Leyuan; Benediktsson, Jón Atli

    2016-12-01

    A novel synthetic aperture radar (SAR) image despeckling method based on structural sparse representation is introduced. The proposed method utilizes the fact that different regions in SAR images correspond to varying terrain reflectivity. Therefore, SAR images can be split into a heterogeneous class (with a varied terrain reflectivity) and a homogeneous class (with a constant terrain reflectivity). In the proposed method, different sparse representation based despeckling schemes are designed by combining the different region characteristics in SAR images. For heterogeneous regions with rich structure and texture information, structural dictionaries are learned to appropriately represent varied structural characteristics. Specifically, each patch in these regions is sparsely coded with the best fitted structural dictionary, thus good structure preservation can be obtained. For homogenous regions without rich structure and texture information, the highly redundant photometric self-similarity is exploited to suppress speckle noise without introducing artifacts. That is achieved by firstly learning the sub-dictionary, then simultaneously sparsely coding for each group of photometrically similar image patches. Visual and objective experimental results demonstrate the superiority of the proposed method over the-state-of-the-art methods.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Modeling and a correlation algorithm for spaceborne SAR signals

    NASA Technical Reports Server (NTRS)

    Wu, C.; Liu, K. Y.; Jin, M.

    1982-01-01

    A mathematical model of a spaceborne synthetic aperture radar (SAR) response is presented. Thhe associated SAR system performance, in terms of the resolution capability, is also discussed. The analysis of spaceborne SAR target response indicates that the SAR correlation problem is a two-dimensional one with a linear shift-variant response function. A new digital processing algorithm is proposed here in order to realize an economical digital SAR correlation system. The proposed algorithm treats the two-dimensional correlation by a combination of frequency domain fast correlation in the azimuth dimension and a time-domain convolver type of operation in the range dimension. Finally, digitally correlated SEASAT satellite SAR imagery is used in an exemplary sense to validate the SAR response model and the new digital processing technique developed.

  6. Retrieval of the thickness of undeformed sea ice from C-band compact polarimetric SAR images

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Dierking, W.; Zhang, J.; Meng, J. M.; Lang, H. T.

    2015-10-01

    In this paper we introduce a parameter for the retrieval of the thickness of undeformed first-year sea ice that is specifically adapted to compact polarimetric SAR images. The parameter is denoted as "CP-Ratio". In model simulations we investigated the sensitivity of CP-Ratio to the dielectric constant, thickness, surface roughness, and incidence angle. From the results of the simulations we deduced optimal conditions for the thickness retrieval. On the basis of C-band CTLR SAR data, which were generated from Radarsat-2 quad-polarization images acquired jointly with helicopter-borne sea ice thickness measurements in the region of the Sea of Labrador, we tested empirical equations for thickness retrieval. An exponential fit between CP-Ratio and ice thickness provides the most reliable results. Based on a validation using other compact polarimetric SAR images from the same region we found a root mean square (rms) error of 8 cm and a maximum correlation coefficient of 0.92 for the retrieval procedure when applying it on level ice of 0.9 m mean thickness.

  7. Cassini RADAR's first SAR observations of Enceladus

    NASA Astrophysics Data System (ADS)

    Mitchell, K. L.; West, R. D.; Anderson, Y.; Team, T.

    2011-12-01

    On November 6th, 2011, Cassini RADAR will have its first opportunity to image a non-Titan icy world at close-range, including a 240 m resolution, 16 km wide Synthetic Aperture RADAR (SAR) swath of southern latitudes down to ~66° S. In addition, the spacecraft will obtain moderate resolution (~1-2 km) HiSAR and scatterometric scans for 2 northern hemisphere regions, and low resolution HiSAR & scatterometric scans (>2 km) of both inbound and outbound hemispheres in their entirety. Passive radiometry will also be obtained, co-spatial to the SAR swath at ~12 km resolution, as well as distant full disk observations. The fly-by in its entirely will provide near-global multi-layered products, massively enriching our remotely-sensed dataset for Enceladus. The goals are to: (1) Enrich our remotely-sensed coverage of Enceladus, providing a complementary imaging dataset that's sensitive to ~2.2-cm texture and dielectric properties, revealing previously undiscovered trends and anomalies; (2) Look for textural and compositional trends radial to the south polar sulci indicative of eruption processes; (3) Give moderate resolution radiometry at a wavelength complementary to CIRS to better characterize the thermal environment; (4) Provide a basis for comparison (limited "ground truth") with Titan imagery in an area covered by high resolution optical and thermal imagery; (5) Show how geology differs between Titan and Enceladus, giving insight into how Titan's geological and environmental peculiarities modulate surface landforms; and (6) Reveal surfaces with unusually high RADAR backscatter at similar resolutions to Titan SAR, to inform models of anomalously high backscatter surfaces on Titan (esp. Xanadu). We will present these observations and preliminary interpretations at the meeting, and discuss how they compare and contrast with previous optical and thermal data.

  8. BioSAR Airborne Biomass Sensing System

    SciTech Connect

    Graham, R.L.; Johnson, P.

    2007-05-24

    This CRADA was developed to enable ORNL to assist American Electronics, Inc. test a new technology--BioSAR. BioSAR is a an airborne, low frequency (80-120 MHz {approx} FM radio frequencies) synthetic aperture radar (SAR) technology which was designed and built for NASA by ZAI-Amelex under Patrick Johnson's direction. At these frequencies, leaves and small branches are nearly transparent and the majority of the energy reflected from the forest and returned to the radar is from the tree trunks. By measuring the magnitude of the back scatter, the volume of the tree trunk and therefore the biomass of the trunks can be inferred. The instrument was successfully tested on tropical rain forests in Panama. Patrick Johnson, with American Electronics, Inc received a Phase II SBIR grant from DOE Office of Climate Change to further test and refine the instrument. Mr Johnson sought ORNL expertise in measuring forest biomass in order for him to further validate his instrument. ORNL provided ground truth measurements of forest biomass at three locations--the Oak Ridge Reservation, Weyerhaeuser Co. commercial pine plantations in North Carolina, and American Energy and Power (AEP) Co. hardwood forests in southern Ohio, and facilitated flights over these forests. After Mr. Johnson processed the signal data from BioSAR instrument, the processed data were given to ORNL and we attempted to derive empirical relationships between the radar signals and the ground truth forest biomass measurements using standard statistical techniques. We were unsuccessful in deriving such relationships. Shortly before the CRADA ended, Mr Johnson discovered that FM signal from local radio station broadcasts had interfered with the back scatter measurements such that the bulk of the signal received by the BioSAR instrument was not backscatter from the radar but rather was local radio station signals.

  9. Adsorption and regenerative oxidation of trichlorophenol with synthetic zeolite: Ozone dosage and its influence on adsorption performance.

    PubMed

    Zhang, Yongjun; Prigent, Bastien; Geißen, Sven-Uwe

    2016-07-01

    Regeneration of loaded adsorbents is a key step for the sustainability of an adsorption process. In this study, ozone was applied to regenerate a synthetic zeolite for the adsorption of trichlorophenol (TCP) as an organic model pollutant. Three initial concentrations of TCP in water phase were used in adsorption tests. After the equilibrium, zeolite loaded different amounts of TCP was dried and then regenerated with ozone gas. It was found that the adsorption capacity of zeolite was increased through three regeneration cycles. However, the adsorption kinetics was compromised after the regeneration with slightly declined 2nd order reaction constants. The ozone demand for the regeneration was highly dependent on the TCP mass loaded onto the zeolite. It was estimated that the mass ratio of ozone to TCP was 1.2 ± 0.3 g O3/g TCP. PMID:27043379

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

    USGS Publications Warehouse

    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.

  11. Antiviral drug discovery against SARS-CoV.

    PubMed

    Wu, Yu-Shan; Lin, Wen-Hsing; Hsu, John T-A; Hsieh, Hsing-Pang

    2006-01-01

    Severe Acute Respiratory Syndrome (SARS) is a life-threatening infectious disease caused by SARS-CoV. In the 2003 outbreak, it infected more than 8,000 people worldwide and claimed the lives of more than 900 victims. The high mortality rate resulted, at least in part, from the absence of definitive treatment protocols or therapeutic agents. Although the virus spreading has been contained, due preparedness and planning, including the successful development of antiviral drugs against SARS-CoV, is necessary for possible reappearance of SARS. In this review, we have discussed currently available strategies for antiviral drug discovery and how these technologies have been utilized to identify potential antiviral agents for the inhibition of SARS-CoV replication. Moreover, progress in the drug development based on different molecular targets is also summarized, including 1) Compounds that block the S protein-ACE2-mediated viral entry; 2) Compounds targeting SARS-CoV M(pro); 3) Compounds targeting papain-like protease 2 (PLP2); 4) Compounds targeting SARS-CoV RdRp; 5) Compounds targeting SARS-CoV helicase; 6) Active compounds with unspecified targets; and 7) Research on siRNA. This review aims to provide a comprehensive account of drug discovery on SARS. The experiences with the SARS outbreak and drug discovery would certainly be an important lesson for the drug development for any new viral outbreaks that may emerge in the future.

  12. Synergistic measurements of ocean winds and waves from SAR

    NASA Astrophysics Data System (ADS)

    Zhang, Biao; Li, Xiaofeng; Perrie, William; He, Yijun

    2015-09-01

    In this study we present a synergistic method to retrieve both ocean surface wave and wind fields from spaceborne quad-polarization (QP) synthetic aperture radar (SAR) imaging mode data. This algorithm integrates QP-SAR wind vector retrieval model and the wave retrieval model, with consideration to the nonlinear mapping relationship between ocean wave spectra and SAR image spectra, in order to synergistically retrieve wind fields and wave directional spectra. The method does not require a priori information on the sea state. It combines the observed VV-polarized SAR image spectra with the retrieved wind vectors from the VH-polarized SAR image, to estimate the wind-generated wave directional spectra. The differences between the observed SAR spectra and optimal SAR image spectra associated with the wind waves are interpreted as the contributions from the swell waves. The retrieved ocean wave spectra are used to estimate the integrated spectral wave parameters such as significant wave heights, wavelengths, wave directions and wave periods. The wind and wave parameters retrieved by QP-SAR are validated against those measured by the National Data Buoy Center (NDBC) directional wave buoys under different sea states. The validation results show that the QP-SAR SAR has potential to simultaneously measure the ocean surface waves and wind fields from space.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Simulation of SAR backscatter for forest vegetation

    NASA Astrophysics Data System (ADS)

    Prajapati, Richa; Kumar, Shashi; Agrawal, Shefali

    2016-05-01

    Synthetic Aperture Radar (SAR) is one of the most recent imaging technology to study the forest parameters. The invincible characteristics of microwave acquisition in cloudy regions and night imaging makes it a powerful tool to study dense forest regions. A coherent combination of radar polarimetry and interferometry (PolInSAR) enhances the accuracy of retrieved biophysical parameters. This paper attempts to address the issue of estimation of forest structural information caused due to instability of radar platforms through simulation of SAR image. The Terai Central Forest region situated at Haldwani area in Uttarakhand state of India was chosen as the study area. The system characteristics of PolInSAR dataset of Radarsat-2 SAR sensor was used for simulation process. Geometric and system specifications like platform altitude, center frequency, mean incidence angle, azimuth and range resolution were taken from metadata. From the field data it was observed that average tree height and forest stand density were 25 m and 300 stems/ha respectively. The obtained simulated results were compared with the sensor acquired master and slave intensity images. It was analyzed that for co-polarized horizontal component (HH), the mean values of simulated and real master image had a difference of 0.3645 with standard deviation of 0.63. Cross-polarized (HV) channel showed better results with mean difference of 0.06 and standard deviation of 0.1 while co-polarized vertical component (VV) did not show similar values. In case of HV polarization, mean variation between simulated and real slave images was found to be the least. Since cross-polarized channel is more sensitive to vegetation feature therefore better simulated results were obtained for this channel. Further the simulated images were processed using PolInSAR inversion modelling approach using three different techniques DEM differencing, Coherence Amplitude Inversion and Random Volume over Ground Inversion. DEM differencing

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

    NASA Astrophysics Data System (ADS)

    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. Possibility of using adsorption refrigeration unit in district heating network

    NASA Astrophysics Data System (ADS)

    Grzebielec, Andrzej; Rusowicz, Artur; Jaworski, Maciej; Laskowski, Rafał

    2015-09-01

    Adsorption refrigeration systems are able to work with heat sources of temperature starting with 50 °C. The aim of the article is to determine whether in terms of technical and economic issues adsorption refrigeration equipment can work as elements that produce cold using hot water from the district heating network. For this purpose, examined was the work of the adsorption air conditioning equipment cooperating with drycooler, and the opportunities offered by the district heating network in Warsaw during the summer. It turns out that the efficiency of the adsorption device from the economic perspective is not sufficient for production of cold even during the transitional period. The main problem is not the low temperature of the water supply, but the large difference between the coefficients of performance, COPs, of adsorption device and a traditional compressor air conditioning unit. When outside air temperature is 25 °C, the COP of the compressor type reaches a value of 4.49, whereas that of the adsorption device in the same conditions is 0.14. The ratio of the COPs is 32. At the same time ratio between the price of 1 kWh of electric power and 1 kWh of heat is only 2.85. Adsorption refrigeration equipment to be able to compete with compressor devices, should feature COPads efficiency to be greater than 1.52. At such a low driving temperature and even changing the drycooler into the evaporative cooler it is not currently possible to achieve.

  17. Using APES for interferometric SAR imaging.

    PubMed

    Palsetia, M R; Li, J

    1998-01-01

    We present an adaptive finite impulse response (FIR) filtering approach, which is referred to as the Amplitude and Phase EStimation (APES) algorithm, for interferometric synthetic aperture radar (SAR) imaging. We compare the APES algorithm with other FIR filtering approaches including the Capon and fast Fourier transform (FFT) methods. We show via both numerical and experimental examples that the adaptive FIR filtering approaches such as Capon and APES can yield more accurate spectral estimates with much lower sidelobes and narrower spectral peaks than the FFT method. We show that although the APES algorithm yields somewhat wider spectral peaks than the Capon method, the former gives more accurate overall spectral estimates and SAR images than the latter and the FFT method.

  18. Non-parametric partitioning of SAR images

    NASA Astrophysics Data System (ADS)

    Delyon, G.; Galland, F.; Réfrégier, Ph.

    2006-09-01

    We describe and analyse a generalization of a parametric segmentation technique adapted to Gamma distributed SAR images to a simple non parametric noise model. The partition is obtained by minimizing the stochastic complexity of a quantized version on Q levels of the SAR image and lead to a criterion without parameters to be tuned by the user. We analyse the reliability of the proposed approach on synthetic images. The quality of the obtained partition will be studied for different possible strategies. In particular, one will discuss the reliability of the proposed optimization procedure. Finally, we will precisely study the performance of the proposed approach in comparison with the statistical parametric technique adapted to Gamma noise. These studies will be led by analyzing the number of misclassified pixels, the standard Hausdorff distance and the number of estimated regions.

  19. Landslide Mapping Using SqueeSAR Data

    NASA Astrophysics Data System (ADS)

    Ferretti, A.; Bellotti, F.; Alberti, S.; Allievi, J.; Del Conte, S.; Tamburini, A.; Broccolato, M.; Ratto, S.; Alberto, W.

    2011-12-01

    SqueeSAR represents the most recent advancement of PSInSAR algorithm. By exploiting signal radar returns both from Permanent and Distributed Scatterers (PS and DS), it is able to detect millimetre displacements over long periods and large areas and to obtain a significant increase in the spatial density of ground measurement points. SqueeSAR analysis is complementary to conventional geological and geomorphological studies in landslide mapping over wide areas, traditionally based on aerial-photo interpretation and field surveys. However, whenever surface displacement rates are low (mm to cm per year), assessing landslide activity is difficult or even impossible without a long-term monitoring tool, as in the case of Deep-seated Gravitational Slope Deformations (DGSD), typically characterized by large areal extent and subtle surface displacement. The availability of surface displacement time series per each measurement point allows one to have both a synoptic overview, at regional scale, as well as an in depth characterization of the instability phenomena analyzed, a meaningful support to the design of traditional monitoring networks and the efficiency testing of remedial works. When data archives are available, SqueeSAR can also provide valuable information before the installation of any terrestrial measurement system. The Italian authorities increasing interest in the application of SqueeSAR as a standard monitoring tool to help hydrogeological risk assessment, resulted in a national project, Piano Straordinario di Telerilevamento (PST), founded by the Ministry of the Environment. The aim of the project was to create the first interferometric database on a national scale for mapping unstable areas. More than 12,000 ERS and ENVISAT radar scenes acquired over Italy were processed spanning the period 1992-2010, proving that, in less than ten years, radar interferometry has become a standard monitoring tool. Recently, many regional governments in Italy have applied

  20. SAR observations in the Gulf of Mexico

    NASA Technical Reports Server (NTRS)

    Sheres, David

    1992-01-01

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

  1. Joint enhancement of multichannel SAR data

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Naveen; Ertin, Emre; Moses, Randolph L.

    2007-04-01

    In this paper we consider the problem of joint enhancement of multichannel Synthetic Aperture Radar (SAR) data. Previous work by Cetin and Karl introduced nonquadratic regularization methods for image enhancement using sparsity enforcing penalty terms. For multichannel data, independent enhancement of each channel is shown to degrade the relative phase information across channels that is useful for 3D reconstruction. We thus propose a method for joint enhancement of multichannel SAR data with joint sparsity constraints. We develop both a gradient-based and a Lagrange-Newton-based method for solving the joint reconstruction problem, and demonstrate the performance of the proposed methods on IFSAR height extraction problem from multi-elevation data.

  2. SAR impulse response with residual chirps.

    SciTech Connect

    Doerry, Armin Walter

    2009-06-01

    A Linear Frequency-Modulated (LFM) chirp is a function with unit amplitude and quadratic phase characteristic. In a focused Synthetic Aperture Radar (SAR) image, a residual chirp is undesired for targets of interest, as it coarsens the manifested resolution. However, for undesired spurious signals, a residual chirp is often advantageous because it spreads the energy and thereby diminishes its peak value. In either case, a good understanding of the effects of a residual LFM chirp on a SAR Impulse Response (IPR) is required to facilitate system analysis and design. This report presents an analysis of the effects of a residual chirp on the IPR. As reference, there is a rich body of publications on various aspects of LFM chirps. A quick search reveals a plethora of articles, going back to the early 1950s. We mention here purely as trivia one of the earlier analysis papers on this waveform by Klauder, et al.

  3. Utilization of spaceborne SAR data for mapping

    NASA Technical Reports Server (NTRS)

    Curlander, J. C.

    1984-01-01

    Recent developments in automated processing of digital SEASAT SAR imagery have made feasible the generation of large-scale high-resolution maps. Standard preprocessing of raw data into digital images results in geometrically distorted imagery. Computer algorithms have been developed for unsupervised pixel location, geometric rectification, and mosaicking of multiple-image frames without ground control points. These algorithms utilize knowledge of the spacecraft trajectory data, the imaging geometry, and the coherent properties of the sensor to generate the required processing parameters. This paper discusses the advantages as well as the inherent limitations of this technique, analyzes the associated errors, and presents results using SEASAT SAR imagery. Also discussed are the results of the recent shuttle imaging radar (SIR-A) experiment as well as a follow-on experiment (SIR-B) planned for 1984.

  4. Automated preprocessing of spaceborne SAR data

    NASA Technical Reports Server (NTRS)

    Curlander, J. C.; Wu, C.; Pang, A.

    1982-01-01

    An efficient algorithm has been developed for estimation of the echo phase delay in spaceborne synthetic aperture radar (SAR) data. This algorithm utilizes the spacecraft ephemeris data and the radar echo data to produce estimates of two parameters: (1) the centroid of the Doppler frequency spectrum f(d) and (2) the Doppler frequency rate. Results are presented from tests conducted with Seasat SAR data. The test data indicates that estimation accuracies of 3 Hz for f(d) and 0.3 Hz/sec for the Doppler frequency rate are attainable. The clutterlock and autofocus techniques used for estimation of f(d) and the Doppler frequency rate, respectively are discussed and the algorithm developed for optimal implementation of these techniques is presented.

  5. Snow and glacier mapping with polarimetric SAR

    NASA Technical Reports Server (NTRS)

    Shi, Jiancheng; Dozier, Jeff; Rott, Helmut; Davis, Robert E.

    1991-01-01

    The objective of this study was to examine the capability of mapping snow and glaciers in alpine regions using synthetic aperture radar (SAR) imagery when topographic information is not available. The topographic effects on the received power for a resolution cell can be explained by the change in illumination area and incidence angle in a slant-rante representation of SAR imagery. The specific polarization signatures and phase difference between HH and VV components are relatively independent of the illuminated are, and the incidence angle has only a small effect on these parameters. They provide a suitable measurement data set for snow and glacier mapping in a high-relief area. The results show that the C-band images of the enhancement factor, the phase difference between HH and VV scattering components, and the normalized cross product of VV scattering elements provide the capability to discriminate among snow with different wetnesses, glaciers, and rocky regions.

  6. Animal models for SARS and MERS coronaviruses

    PubMed Central

    Gretebeck, Lisa M; Subbarao, Kanta

    2015-01-01

    The emergence of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) and Middle East Respiratory Syndrome coronavirus (MERS-CoV), two strains of animal coronaviruses that crossed the species barrier to infect and cause severe respiratory infections in humans within the last 12 years, have taught us that coronaviruses represent a global threat that does not recognize international borders. We can expect to see other novel coronaviruses emerge in the future. An ideal animal model should reflect the clinical signs, viral replication and pathology seen in humans. In this review, we present factors to consider in establishing an animal model for the study of novel coronaviruses and compare the different animal models that have been employed to study SARS-CoV and MERS-CoV. PMID:26184451

  7. A sea ice concentration estimation algorithm utilizing radiometer and SAR data

    NASA Astrophysics Data System (ADS)

    Karvonen, J.

    2014-09-01

    We have studied the possibility of combining the high-resolution synthetic aperture radar (SAR) segmentation and ice concentration estimated by radiometer brightness temperatures. Here we present an algorithm for mapping a radiometer-based concentration value for each SAR segment. The concentrations are estimated by a multi-layer perceptron (MLP) neural network which has the AMSR-2 (Advanced Microwave Scanning Radiometer 2) polarization ratios and gradient ratios of four radiometer channels as its inputs. The results have been compared numerically to the gridded Finnish Meteorological Institute (FMI) ice chart concentrations and high-resolution AMSR-2 ASI (ARTIST Sea Ice) algorithm concentrations provided by the University of Hamburg and also visually to the AMSR-2 bootstrap algorithm concentrations, which are given in much coarser resolution. The differences when compared to FMI daily ice charts were on average small. When compared to ASI ice concentrations, the differences were a bit larger, but still small on average. According to our comparisons, the largest differences typically occur near the ice edge and sea-land boundary. The main advantage of combining radiometer-based ice concentration estimation and SAR segmentation seems to be a more precise estimation of the boundaries of different ice concentration zones.

  8. Optimal combination of InSAR and GPS for measuring interseismic crustal deformation

    NASA Astrophysics Data System (ADS)

    Wei, Meng; Sandwell, David; Smith-Konter, Bridget

    2010-07-01

    High spatial resolution measurements of interseismic deformation along major faults are critical for understanding the earthquake cycle and for assessing earthquake hazard. We propose a new remove/filter/restore technique to optimally combine GPS and InSAR data to measure interseismic crustal deformation, considering the spacing of GPS stations in California and the characteristics of interseismic signal and noise using InSAR. To constrain the longer wavelengths (>40 km) we use GPS measurements, combined with a dislocation model, and for the shorter wavelength information we rely on InSAR measurements. Expanding the standard techniques, which use a planar ramp to remove long wavelength error, we use a Gaussian filter technique. Our method has the advantage of increasing the signal-to-noise ratio, controlling the variance of atmosphere error, and being isotropic. Our theoretical analysis indicates this technique can improve the signal-to-noise ratio by up to 20%. We test this method along three segments of the San Andreas Fault (Southern section near Salton Sea, Creeping section near Parkfield and Mojave/Big Bend section near Los Angeles), and find improvements of 26%, 11% and 8% in these areas, respectively. Our data shows a zone of uplift to the west of the Creeping section of the San Andreas Fault and an area of subsidence near the city of Lancaster. This work suggests that after only 5 years of data collection, ALOS interferograms will provide a major improvement in measuring details of interseismic deformation.

  9. Interferometric SAR coherence classification utility assessment

    SciTech Connect

    Yocky, D.A.

    1998-03-01

    The classification utility of a dual-antenna interferometric synthetic aperture radar (IFSAR) is explored by comparison of maximum likelihood classification results for synthetic aperture radar (SAR) intensity images and IPSAR intensity and coherence images. The addition of IFSAR coherence improves the overall classification accuracy for classes of trees, water, and fields. A threshold intensity-coherence classifier is also compared to the intensity-only classification results.

  10. Alaska SAR Facility mass storage, current system

    NASA Technical Reports Server (NTRS)

    Cuddy, David; Chu, Eugene; Bicknell, Tom

    1993-01-01

    This paper examines the mass storage systems that are currently in place at the Alaska SAR Facility (SAF). The architecture of the facility will be presented including specifications of the mass storage media that are currently used and the performances that we have realized from the various media. The distribution formats and media are also discussed. Because the facility is expected to service future sensors, the new requirements and possible solutions to these requirements are also discussed.

  11. Processing of polarametric SAR images. Final report

    SciTech Connect

    Warrick, A.L.; Delaney, P.A.

    1995-09-01

    The objective of this work was to develop a systematic method of combining multifrequency polarized SAR images. It is shown that the traditional methods of correlation, hard targets, and template matching fail to produce acceptable results. Hence, a new algorithm was developed and tested. The new approach combines the three traditional methods and an interpolation method. An example is shown that demonstrates the new algorithms performance. The results are summarized suggestions for future research are presented.

  12. A 3-D SAR approach to IFSAR processing

    SciTech Connect

    DOERRY,ARMIN W.; BICKEL,DOUGLAS L.

    2000-03-01

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

  13. SAR11 bacteria linked to ocean anoxia and nitrogen loss.

    PubMed

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

    2016-08-11

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

  14. Monitoring The Dynamics Of Hyper-Saline Environments With Polarimetric SAR: Death Valley, California Example

    NASA Astrophysics Data System (ADS)

    Lasne, Y.; McDonald, K.; Paillou, P.; Freeman, A.; Chapman, B.; Farr, T.; Ruffié, G.; Malézieux, J.

    2008-12-01

    Soil salinization in arid and semi-arid regions still remains one of the most important threats not only for socio-economical issues when dealing with water ressources management, but also for ecological matters such as: desertification, climate changes, and biomass reduction. Then, monitoring and mapping of soil salinity distribution represent today a key challenge in our understanding of such environmental processes. Being highly dependent on the dielectric properties of soils, synthetic aperture radar (SAR) appears to be an efficient tool for the remote sensing of hyper-saline environments. More precisely, the influence of saline deposits on SAR imagery lies in the solubility and ionic properties of the minerals which strongly influence both real and imaginary parts of the complex permittivity of such deposits, and thus the radar backscattering coefficient. Based on temporal series acquired with spaceborne SAR systems (ALOS/PALSAR, SIR-C) over the Death Valley (CA), we show that the copolarized backscattering ratio and phase difference derived from SAR data can be used as suitable indicators to monitor the dynamics of hyper-saline deposits. In particular, we propose these copolar parameters to follow the variations in the dielectric properties of moistened and salt-affected soils on a seasonal time scale because of the close relationship between the salinity (governed by the soil moisture content) and the complex permittivity of the soils. We also highlight a strong temporal correlation between the copolar parameters and weather data since precipitation events control the soil moisture and salinity. In order to allow for a better interpretation of the saline deposits signatures observed on SAR data, we also perform analytical simulations of the radar backscattering associated with saline deposits by means of the IEM scattering model. Using laboratory and in~ situ dielectric measurements as input parameters, we simulate the copolar ratio and phase difference as

  15. Formation geometries for multistatic SAR tomography

    NASA Astrophysics Data System (ADS)

    Fasano, Giancarmine; Renga, Alfredo; D'Errico, Marco

    2014-03-01

    This paper analyzes relative orbit design for multi-satellite radar missions aimed at multistatic SAR tomography. To this end, formation requirements and performance parameters are derived by adapting existing models for SAR tomography to single pass techniques. Then, relative trajectory design is carried out on the basis of an analytical relative motion model including secular J2 effects. By properly scaling the differences in orbital parameters, different formation geometries enable uniform sampling of the effective baseline along the whole orbit. The difference among the possible choices lies in latitude coverage, formation stability, and collision avoidance aspects. A numerical example of relative trajectory design is discussed considering L-band as operating frequency. In particular, achievable height resolution and unambiguous height along the orbit are pointed out for a multi-cartwheel, a multi-pendulum, and a multi-helix formation. In view of future implementation of a multi-satellite SAR tomography mission, new concepts aimed at the reduction of required satellites, and long term evolution of designed formations, are also discussed.

  16. The InSAR Scientific Computing Environment

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    We have developed a flexible and extensible Interferometric SAR (InSAR) Scientific Computing Environment (ISCE) for geodetic image processing. ISCE was designed from the ground up as a geophysics community tool for generating stacks of interferograms that lend themselves to various forms of time-series analysis, with attention paid to accuracy, extensibility, and modularity. The framework is python-based, with code elements rigorously componentized by separating input/output operations from the processing engines. This allows greater flexibility and extensibility in the data models, and creates algorithmic code that is less susceptible to unnecessary modification when new data types and sensors are available. In addition, the components support provenance and checkpointing to facilitate reprocessing and algorithm exploration. The algorithms, based on legacy processing codes, have been adapted to assume a common reference track approach for all images acquired from nearby orbits, simplifying and systematizing the geometry for time-series analysis. The framework is designed to easily allow user contributions, and is distributed for free use by researchers. ISCE can process data from the ALOS, ERS, EnviSAT, Cosmo-SkyMed, RadarSAT-1, RadarSAT-2, and TerraSAR-X platforms, starting from Level-0 or Level 1 as provided from the data source, and going as far as Level 3 geocoded deformation products. With its flexible design, it can be extended with raw/meta data parsers to enable it to work with radar data from other platforms

  17. Using APES for interferometric SAR imaging

    NASA Astrophysics Data System (ADS)

    Li, Jian; Palsetia, Marzban

    1996-06-01

    In this paper, we present an adaptive FIR filtering approach, which is referred to as the APES (amplitude and phase estimation of a sinusoid) algorithm, for interferometric SAR imaging. We apply the APES algorithm on the data obtained from two vertically displaced apertures of a SAR system to obtain the complex amplitude and the phase difference estimates, which are proportional to the radar cross section and the height of the scatterer, respectively, at the frequencies of interest. We also demonstrate how the APES algorithm can be applied to data matrices with large dimensions without incurring high computational overheads. We compare the APES algorithm with other FIR filtering approaches including the Capon and FFT methods. We show via both numerical and experimental examples that the adaptive FIR filtering approaches such as Capon and APES can yield more accurate spectral estimates with much lower sidelobes and narrower spectral peaks than the FFT method. We show that although the APES algorithm yields somewhat wider spectral peaks than the Capon method, the former gives more accurate overall spectral estimates and SAR images than the latter and the FFT method.

  18. Fast SAR image change detection using Bayesian approach based difference image and modified statistical region merging.

    PubMed

    Zhang, Han; Ni, Weiping; Yan, Weidong; Bian, Hui; Wu, Junzheng

    2014-01-01

    A novel fast SAR image change detection method is presented in this paper. Based on a Bayesian approach, the prior information that speckles follow the Nakagami distribution is incorporated into the difference image (DI) generation process. The new DI performs much better than the familiar log ratio (LR) DI as well as the cumulant based Kullback-Leibler divergence (CKLD) DI. The statistical region merging (SRM) approach is first introduced to change detection context. A new clustering procedure with the region variance as the statistical inference variable is exhibited to tailor SAR image change detection purposes, with only two classes in the final map, the unchanged and changed classes. The most prominent advantages of the proposed modified SRM (MSRM) method are the ability to cope with noise corruption and the quick implementation. Experimental results show that the proposed method is superior in both the change detection accuracy and the operation efficiency.

  19. Design of a spaceborne SAR at higher incidence angle using alternate transmitted chirp slope reversal technique

    NASA Astrophysics Data System (ADS)

    Jha, A. M.; Majmudar, Archana; Pillai, N. S.

    The system design of a spaceborne SAR at a higher look angle calls for tradeoffs among antenna complexity, wider swath, and the required range ambiguity ratio (RAR). The requirement of minimum-acceptable RAR even for a nominal swath may necessitate a larger antenna width, complex weighting, and highly asymmetrical antenna elevation patterns. The SCANSAR concept for a wider swath leads to a tradeoff against the azimuth resolution and system complexity. The scheme proposed, known as the alternate transmitted chirp slope reversal (ATCSR) method, can suppress the range ambiguity and consequently reduce the antenna complexity without increasing the system complexity. A case study of a conceptual C-band SAR at 50-deg incidence angle for a swath of about 150 km, conducted utilizing the ATCSR method for uniform antenna elevation pattern, is presented.

  20. A new maximum-likelihood change estimator for two-pass SAR coherent change detection

    DOE PAGES

    Wahl, Daniel E.; Yocky, David A.; Jakowatz, Jr., Charles V.; Simonson, Katherine Mary

    2016-01-11

    In past research, two-pass repeat-geometry synthetic aperture radar (SAR) coherent change detection (CCD) predominantly utilized the sample degree of coherence as a measure of the temporal change occurring between two complex-valued image collects. Previous coherence-based CCD approaches tend to show temporal change when there is none in areas of the image that have a low clutter-to-noise power ratio. Instead of employing the sample coherence magnitude as a change metric, in this paper, we derive a new maximum-likelihood (ML) temporal change estimate—the complex reflectance change detection (CRCD) metric to be used for SAR coherent temporal change detection. The new CRCD estimatormore » is a surprisingly simple expression, easy to implement, and optimal in the ML sense. As a result, this new estimate produces improved results in the coherent pair collects that we have tested.« less

  1. Fast SAR Image Change Detection Using Bayesian Approach Based Difference Image and Modified Statistical Region Merging

    PubMed Central

    Ni, Weiping; Yan, Weidong; Bian, Hui; Wu, Junzheng

    2014-01-01

    A novel fast SAR image change detection method is presented in this paper. Based on a Bayesian approach, the prior information that speckles follow the Nakagami distribution is incorporated into the difference image (DI) generation process. The new DI performs much better than the familiar log ratio (LR) DI as well as the cumulant based Kullback-Leibler divergence (CKLD) DI. The statistical region merging (SRM) approach is first introduced to change detection context. A new clustering procedure with the region variance as the statistical inference variable is exhibited to tailor SAR image change detection purposes, with only two classes in the final map, the unchanged and changed classes. The most prominent advantages of the proposed modified SRM (MSRM) method are the ability to cope with noise corruption and the quick implementation. Experimental results show that the proposed method is superior in both the change detection accuracy and the operation efficiency. PMID:25258740

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

    SciTech Connect

    Doerry, Armin Walter

    2012-12-01

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

  3. Control Measures for Severe Acute Respiratory Syndrome (SARS) in Taiwan

    PubMed Central

    Twu, Shiing-Jer; Chen, Tzay-Jinn; Chen, Chien-Jen; Olsen, Sonja J.; Lee, Long-Teng; Fisk, Tamara; Hsu, Kwo-Hsiung; Chang, Shan-Chwen; Chen, Kow-Tong; Chiang, I-Hsin; Wu, Yi-Chun; Wu, Jiunn-Shyan

    2003-01-01

    As of April 14, 2003, Taiwan had had 23 probable cases of severe acute respiratory syndrome (SARS), all imported. Taiwan isolated these first 23 patients with probable SARS in negative-pressure rooms; extensive personal protective equipment was used for healthcare workers and visitors. For the first 6 weeks of the SARS outbreak, recognized spread was limited to one healthcare worker and three household contacts. PMID:12781013

  4. The adsorption of HCl on volcanic ash

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Xochilt; Schiavi, Federica; Keppler, Hans

    2016-03-01

    data provided here, the gas compositions in equilibrium with the ash surfaces can be calculated. In particular, for dacitic composition, the molar ratio of S/Cl adsorbed to the ash surface is related to the molar S/Cl ratio in the gas phase according to the equation ln ⁡(S / Cl) adsorbed = 2855T-1 + 0.28 ln ⁡(S / Cl) gas - 11.14. Our data also show that adsorption on ash will significantly reduce the fraction of HCl reaching the stratosphere, only if the initial HCl content in the volcanic gas is low (<1 mol%). For higher initial HCl concentrations, adsorption on ash has only a minor effect. While HCl scavenging by hydrometeors may remove a considerable fraction of HCl from the eruption column, recent models suggest that this process is much less efficient than previously thought. Our experimental data therefore support the idea that the HCl loading from major explosive eruptions may indeed cause severe depletions of stratospheric ozone.

  5. New Adsorption Methods.

    ERIC Educational Resources Information Center

    Wankat, Phillip C.

    1984-01-01

    Discusses a simple method for following the movement of a solute in an adsorption or ion exchange system. This movement is used to study a variety of operational methods, including continuous flow and pulsed flow counter-current operations and simulated counter-current systems. Effect of changing thermodynamic variables is also considered. (JM)

  6. Sulfate adsorption on goethite

    SciTech Connect

    Rietra, R.P.J.J.; Hiemstra, T.; Riemsdijk, W.H. van

    1999-10-15

    Recent spectroscopic work has suggested that only one surface species of sulfate is dominant on hematite. Sulfate is therefore a very suitable anion to test and develop adsorption models for variable charge minerals. The authors have studied sulfate adsorption on goethite covering a large range of sulfate concentrations, surface coverages, pH values, and electrolyte concentrations. Four different techniques were used to cover the entire range of conditions. For characterization at low sulfate concentrations, below the detection limit of sulfate with ICP-AES, the authors used proton-sulfate titrations at constant pH. Adsorption isotherms were studied for the intermediate sulfate concentration range. Acid-base titrations in sodium sulfate and electromobility were used for high sulfate concentrations. All the data can be modeled with one adsorbed species if it is assumed that the charge of adsorbed sulfate is spatially distributed in the interface. The charge distribution of sulfate follows directly from modeling the proton-sulfate adsorption stoichoimemtry sine this stoichiometry is independent of the intrinsic affinity constant of sulfate. The charge distribution can be related to the structure of the surface complex by use of the Pauling bond valence concept and is in accordance with the microscopic structure found by spectroscopy. The intrinsic affinity constant follows from the other measurements. Modeling of the proton-ion stoichoimetry with the commonly used 2-pK models, where adsorbed ions are treated as point charges, is possible only if at least two surface species for sulfate are used.

  7. SEPARATION BY ADSORPTION

    DOEpatents

    Lowe, C.S.

    1959-06-16

    Separation of Pu from fission products by adsorption on hydrous aluminum silicate is described. The Pu in a HNO/sub 3/ solution is oxidized to the hexavalent state and contacted with the silicate which adsorbs fission products. (T.R.H.)

  8. Geometric registration and rectification of spaceborne SAR imagery

    NASA Technical Reports Server (NTRS)

    Curlander, J. C.; Pang, S. N.

    1982-01-01

    This paper describes the development of automated location and geometric rectification techniques for digitally processed synthetic aperture radar (SAR) imagery. A software package has been developed that is capable of determining the absolute location of an image pixel to within 60 m using only the spacecraft ephemeris data and the characteristics of the SAR data collection and processing system. Based on this location capability algorithms have been developed that geometrically rectify the imagery, register it to a common coordinate system and mosaic multiple frames to form extended digital SAR maps. These algorithms have been optimized using parallel processing techniques to minimize the operating time. Test results are given using Seasat SAR data.

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

    PubMed

    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

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

    PubMed

    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.

  11. Crop identification of SAR data using digital textural analysis

    NASA Technical Reports Server (NTRS)

    Nuesch, D. R.

    1983-01-01

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

  12. Epipolar geometry comparison of SAR and optical camera

    NASA Astrophysics Data System (ADS)

    Li, Dong; Zhang, Yunhua

    2016-03-01

    In computer vision, optical camera is often used as the eyes of computer. If we replace camera with synthetic aperture radar (SAR), we will then enter a microwave vision of the world. This paper gives a comparison of SAR imaging and camera imaging from the viewpoint of epipolar geometry. The imaging model and epipolar geometry of the two sensors are analyzed in detail. Their difference is illustrated, and their unification is particularly demonstrated. We hope these may benefit researchers in field of computer vision or SAR image processing to construct a computer SAR vision, which is dedicated to compensate and improve human vision by electromagnetically perceiving and understanding the images.

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

    PubMed Central

    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

  14. Random sequential adsorption on partially covered surfaces

    NASA Astrophysics Data System (ADS)

    Adamczyk, Zbigniew; Weroński, Paweł

    1998-06-01

    The random sequential adsorption (RSA) approach was used to analyze adsorption of hard spheres at surfaces precovered with smaller sized particles. Numerical simulations were performed to determine the available surface function φl of larger particles for various particle size ratios λ=al/as and surface concentration of smaller particles θs. It was found that the numerical results were in a reasonable agreement with the formula stemming from the scaled particle theory with the modification for the sphere/sphere geometry. Particle adsorption kinetics was also determined in terms of the RSA simulations. By extrapolating the θl vs τ-1/2 dependencies, the jamming concentrations of larger spheres θl∞ were determined as a function of the initial smaller sphere concentration. It was found that θl∞ were considerably reduced by the presence of smaller sized particles, especially for λ≫1. The pair correlation function g of larger particles in the jamming state was also determined, showing more short range ordering (at the same θl) in comparison with monodisperse systems. The theoretical predictions stemming from our calculations suggest that the presence of trace amounts of very small particles may exert a decisive influence on adsorption of larger particles.

  15. Relationships between autofocus methods for SAR and self-survey techniques for SONAR. [Synthetic Aperture Radar (SAR)

    SciTech Connect

    Wahl, D.E.; Jakowatz, C.V. Jr.; Ghiglia, D.C.; Eichel, P.H.

    1991-01-01

    Autofocus methods in SAR and self-survey techniques in SONAR have a common mathematical basis in that they both involve estimation and correction of phase errors introduced by sensor position uncertainties. Time delay estimation and correlation methods have been shown to be effective in solving the self-survey problem for towed SONAR arrays. Since it can be shown that platform motion errors introduce similar time-delay estimation problems in SAR imaging, the question arises as to whether such techniques could be effectively employed for autofocus of SAR imagery. With a simple mathematical model for motion errors in SAR, we will show why such correlation/time-delay techniques are not nearly as effective as established SAR autofocus algorithms such as phase gradient autofocus or sub-aperture based methods. This analysis forms an important bridge between signal processing methodologies for SAR and SONAR. 5 refs., 4 figs.

  16. InSAR Scientific Computing Environment

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  17. Polymorphism of SARS-CoV genomes.

    PubMed

    Shang, Lei; Qi, Yan; Bao, Qi-Yu; Tian, Wei; Xu, Jian-Cheng; Feng, Ming-Guang; Yang, Huan-Ming

    2006-04-01

    In this work, severe acute respiratory syndrome associated coronavirus (SARS-CoV) genome BJ202 (AY864806) was completely sequenced. The genome was directly accessed from the stool sample of a patient in Beijing. Comparative genomics methods were used to analyze the sequence variations of 116 SARS-CoV genomes (including BJ202) available in the NCBI GenBank. With the genome sequence of GZ02 as the reference, there were 41 polymorphic sites identified in BJ202 and a total of 278 polymorphic sites present in at least two of the 116 genomes. The distribution of the polymorphic sites was biased over the whole genome. Nearly half of the variations (50.4%, 140/278) clustered in the one third of the whole genome at the 3' end (19.0 kb-29.7 kb). Regions encoding Orf10-11, Orf3/4, E, M and S protein had the highest mutation rates. A total of 15 PCR products (about 6.0 kb of the genome) including 11 fragments containing 12 known polymorphic sites and 4 fragments without identified polymorphic sites were cloned and sequenced. Results showed that 3 unique polymorphic sites of BJ202 (positions 13 804, 15 031 and 20 792) along with 3 other polymorphic sites (26 428, 26 477 and 27 243) all contained 2 kinds of nucleotides. It is interesting to find that position 18379 which has not been identified to be polymorphic in any of the other 115 published SARS-CoV genomes is actually a polymorphic site. The nucleotide composition of this site is A (8) to G (6). Among 116 SARS-CoV genomes, 18 types of deletions and 2 insertions were identified. Most of them were related to a 300 bp region (27,700-28,000) which encodes parts of the putative ORF9 and ORF10-11. A phylogenetic tree illustrating the divergence of whole BJ202 genome from 115 other completely sequenced SARS-CoVs was also constructed. BJ202 was phylogeneticly closer to BJ01 and LLJ-2004. PMID:16625834

  18. Competitive adsorption, displacement, and transport of organic matter on iron oxide: I. Competitive adsorption

    NASA Astrophysics Data System (ADS)

    Gu, Baohua; Mehlhorn, Tonia L.; Liang, Liyuan; McCarthy, John F.

    1996-06-01

    Different organic compounds or fractions of natural organic matter (NOM) show different adsorption affinities ( K) and capacities ( qm) on mineral surfaces. We hypothesize that these different organic compounds or fractions compete for adsorption when surface adsorption sites are limited. In this study, competitive adsorption of binary mixtures of Suwannee River NOM (SR-NOM), polyacrylic acid (PAA), phthalic acid, and salicylic acid on iron oxide was investigated at a constant solid:solution ratio, temperature, and pressure, but at varying C weight fractions, pH, and solution concentrations of the mixture. Results revealed that, in general, PAA is the most competitive whereas SR-NOM is more competitive than phthalic and salicylic acids. The competitive adsorption of these organic compounds is pH-dependent. At pH < 4, PAA becomes less competitive than SR-NOM or phthalic and salicylic acids. The competition among these organic compounds may be related to their carboxyl functional groups and their molecular structure. The overall strong competitiveness of PAA at pH > 4 in comparison with other organics is attributed to its high carboxyl density and linear molecular structure, which promote strong surface complexation with iron oxide. Because of the heterogeneity or polydispersity of NOM, this research indicates that NOM partitioning and transport in the subsurface soil environment are influenced by the dynamic competitive interactions between NOM subcomponents (or fractions). This process ultimately influences the distribution, interaction, and cotransport of contaminants and mineral colloids that are associated with NOM.

  19. Soil moisture estimation in cereal fields using multipolarized SAR data

    NASA Astrophysics Data System (ADS)

    Alvarez-Mozos, J.; Izagirre, A.; Larrañaga, A.

    2012-04-01

    The retrieval of soil moisture from remote sensing data is an extremely active research topic with applications on a wide range of disciplines. Microwave observations represent the most viable approach due to the influence of soils' dielectric constant (and thus soil moisture) on both the emission and backscatter of waves in this region of the spectrum. Passive observations provide higher temporal resolutions, whereas active (SAR) observations have a higher spatial detail. Even if operational moisture products, based on passive data, exist, retrieval algorithms using active observations still face several problems. Surface roughness and vegetation cover are probably the disturbing factors most affecting the accuracy of soil moisture retrievals. In this communication the influence of vegetation cover is investigated and a retrieval technique based on multipolarized C band SAR observations is proposed. With this aim a dedicated field campaign was carried out in La Tejería watershed (north of Spain) from January to August 2010. Eight RADARSAT-2 Fine-Quadpol scenes were acquired in order to investigate the role of vegetation cover on the retrieval of soil moisture, as well as the sensitivity of different polarimetric parameters to vegetation cover condition. Coinciding with image acquisitions soil moisture, plant density and crop height measurements were acquired in eight control fields (cultivated with barley and wheat crops). The sensitivity of backscatter coefficients (in HH, HV and VV polarizations) and backscatter ratios (p=HH/VV and q=HV/VV) to soil moisture and crop condition were evaluated and the semi-empirical Water Cloud Model was fitted to the observations. The results obtained showed that the contribution of the cereal vegetation cover was minimal in HH and HV polarizations, whereas the VV channel appeared to be significantly attenuated by the cereal cover, so its value decreased as the crops grew. As a result, the ratios p and q showed a very good

  20. Ibuprofen adsorption in four agricultural volcanic soils.

    PubMed

    Estevez, Esmeralda; Hernandez-Moreno, Jose Manuel; Fernandez-Vera, Juan Ramon; Palacios-Diaz, Maria Pino

    2014-01-15

    Ibuprofen (IB) is a high environmental risk drug and one of the most frequently prescribed in human medicine. Recently, IB has been detected in Gran Canaria in reclaimed water for irrigation and in groundwater. Adsorption was studied in four volcanic soils from three islands of the Canarian Archipelago. Once the biodegradation process has been excluded from the experimental conditions, a batch method was applied using initial concentrations of 1-5-10-20-50-100-200 mg L(-1) and two soil/water ratios (w/V): 1:5 (OECD, 2000) and 1:1. Non-linear and linearized Langmuir and Freundlich equations were well fitted. The wide IB range tested in our batch studies allowed us to measure experimental adsorption values close to the maximum adsorption capacity (S(max)) as estimated by Langmuir, making it possible thereby to validate the use of the Langmuir equation when there is a burst of contamination at high concentration. The distribution coefficient (Kd), S(max) and Retardation Factor (RF) varied from 0.04 to 0.5 kg L(-1), 4-200 mgk g(-1) and 1.2-1.9, respectively. The lowest S(max) and Kd values were found for the 1:1S/W ratio whereas most batch studies employ 1:5S/W ratios, thus obtaining higher adsorption parameters than when considering field conditions (1:1). Despite the high anion retention of andic soils, similar Kd and RF to those reported for other soils were obtained in 1:5, while high S(max) was found. Our results demonstrate that IB adsorption in volcanic areas responds not only to the soil properties commonly cited in adsorption studies, but also depends on andic properties, sorbent concentration and Dissolved Organic Carbon, the higher values of which are related to the lower Kd and S(max). The low RF and low detection frequency of the IB in groundwater suggests that a) reclaimed water irrigation is not the main source of IB, and b) the existence of some uncontrolled water disposal points in the zone.

  1. Phase 2 Methyl Iodide Deep-Bed Adsorption Tests

    SciTech Connect

    Soelberg, Nick; Watson, Tony

    2014-09-01

    Nuclear fission produces fission products (FPs) and activation products, including iodine-129, which could evolve into used fuel reprocessing facility off-gas systems, and could require off-gas control to limit air emissions to levels within acceptable emission limits. Research, demonstrations, and some reprocessing plant experience have indicated that diatomic iodine can be captured with efficiencies high enough to meet regulatory requirements. Research on the capture of organic iodides has also been performed, but to a lesser extent. Several questions remain open regarding the capture of iodine bound in organic compounds. Deep-bed methyl iodide adsorption testing has progressed according to a multi-laboratory methyl iodide adsorption test plan. This report summarizes the second phase of methyl iodide adsorption work performed according to this test plan using the deep-bed iodine adsorption test system at the Idaho National Laboratory (INL), performed during the second half of Fiscal Year (FY) 2014. Test results continue to show that methyl iodide adsorption using AgZ can achieve total iodine decontamination factors (DFs, ratios of uncontrolled and controlled total iodine levels) above 1,000, until breakthrough occurred. However, mass transfer zone depths are deeper for methyl iodide adsorption compared to diatomic iodine (I2) adsorption. Methyl iodide DFs for the Ag Aerogel test adsorption efficiencies were less than 1,000, and the methyl iodide mass transfer zone depth exceeded 8 inches. Additional deep-bed testing and analyses are recommended to (a) expand the data base for methyl iodide adsorption under various conditions specified in the methyl iodide test plan, and (b) provide more data for evaluating organic iodide reactions and reaction byproducts for different potential adsorption conditions.

  2. Carbonaceous materials for adsorptive refrigerators

    NASA Astrophysics Data System (ADS)

    Buczek, B.; Wolak, E.

    2012-06-01

    Carbon monoliths prepared from hard coal precursors were obtained. The porous structure of the monoliths was evaluated on the basis of nitrogen adsorption — desorption equilibrium data. The investigated monoliths have a well-developed microporous structure with significant specific surface area (S BET ). Equilibrium studies of methanol vapour adsorption were used to characterize the methanol adsorptive capacity that was determined using a volumetric method. The heat of wetting by methanol was determined in order to estimate the energetic effects of the adsorption process. The results of the investigations show that all monoliths exhibit high adsorption capacity and high heat of wetting with methanol.

  3. Multi-Temporal SAR Interferometry for Landslide Monitoring

    NASA Astrophysics Data System (ADS)

    Dwivedi, R.; Narayan, A. B.; Tiwari, A.; Dikshit, O.; Singh, A. K.

    2016-06-01

    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.

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

    PubMed

    Andrey, Diego O; Jousselin, Ambre; Villanueva, Maite; Renzoni, Adriana; Monod, Antoinette; Barras, Christine; Rodriguez, Natalia; Kelley, William L

    2015-01-01

    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. PMID:26275216

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

    PubMed

    Andrey, Diego O; Jousselin, Ambre; Villanueva, Maite; Renzoni, Adriana; Monod, Antoinette; Barras, Christine; Rodriguez, Natalia; Kelley, William L

    2015-01-01

    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.

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

    PubMed Central

    Villanueva, Maite; Renzoni, Adriana; Monod, Antoinette; Barras, Christine; Rodriguez, Natalia; Kelley, William L.

    2015-01-01

    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. PMID:26275216

  7. Microemulsion synthesis of hydroxyapatite nanomaterials and their adsorption behaviors for Cr3+ ions

    NASA Astrophysics Data System (ADS)

    Gao, Y. L.; Wang, X. S.; Cui, H. H.; Mu, M. M.; Huang, F. Z.

    2016-05-01

    Hydroxyapatite (HAP) nanoparticles with different morphologies, such as nanorods, nanospheres, and their mixtures were successfully synthesized by microemulsion method with soluble additive. Their adsorption capacity for Cr3+ ion was investigated. Most of the Cr3+ were absorbed by HAP within 60 min. The adsorption capacity of the HAP nanospheres was the best, and the maximum Cr3+ removal ratio was 96.4%, revealing that the metal ions adsorption by HAP is dependent on the morphology of its particles.

  8. Classification and monitoring of reed belts using dual-polarimetric TerraSAR-X time series

    NASA Astrophysics Data System (ADS)

    Heine, Iris; Jagdhuber, Thomas; Itzerott, Sibylle

    2016-04-01

    The shorelines of lakes in northeastern Germany are often covered by reed. These reed belts fulfill an important function as erosion protection, biotope for animals, carbon storage, and as cleaning filter for lake water. However, despite their importance for the limnic ecosystem, reed vegetation in northeastern Germany is not regularly monitored. In this research study we investigate the potential of synthetic aperture radar polarimetry (PolSAR) for seasonal monitoring of reed vegetation. SAR imagery enables sunlight- and (almost) weather-independent monitoring. Polarimetric decomposition techniques allow the physical characterization of the scattering scenario and the involved scatterers. Our study is based on 19 dual-polarimetric (HH/VV) TerraSAR-X images acquired between August 2014 and May 2015. We calculated different polarimetric indices comprising the HH and VV intensities, the dual-polarimetric coherency matrix with dominant and mean alpha scattering angles, entropy and anisotropy (normalized eigen-value difference) as well as combinations of entropy and anisotropy for the analysis of the scattering scenarios. The reed areas in the TerraSAR-X images were classified using a random forest algorithm and validated with high-resolution digital orthophotos. The time series analysis of the reed belts revealed significant seasonal changes in the double bounce sensitive parameters (intensity ratio HH/VV and intensity difference HH-VV, the co-polarimetric coherence phase and the dominant and mean alpha scattering angles). Additionally, the dual-polarimetric coherence (amplitude), anisotropy, entropy, and anisotropy-entropy-combinations showed seasonal changes of reed. In summer, the reed areas are characterized within the X-band SAR data by volume scattering, whereas in winter double-bounce scattering dominates. The volume scattering in summer is caused predominantly by reed leaves. In autumn, the leaves start to wither and fall off, so that in winter predominately

  9. Extracorporeal adsorption of endotoxin.

    PubMed

    Staubach, K H; Rosenfeldt, J A; Veit, O; Bruch, H P

    1997-02-01

    In a porcine endotoxin shock model using a continuous intravenous endotoxin infusion of 250 ng/kg body weight per hour, the cardiorespiratory and hematologic parameters were studied while applying a new on-line polymyxin B immobilized adsorption system. This preliminary report shows that the new adsorbent can remove endotoxin selectively from the circulation and confers a good amount of protection from endotoxin-induced cardiopulmonary decompensation as well as hematologic alterations. Survival time could be extended from 216 min to 313 min. Whereas cardiac output and mean arterial pressure declined critically after 3 h in the controls, the treated group remained stable for another 3 h. These data show that endotoxin adsorption by polymyxin B coupled covalently to acrylic spheres as an adjunctive on-line measure in the septic syndrome seems feasible. PMID:10225785

  10. Regenerable adsorption system

    NASA Technical Reports Server (NTRS)

    Roychoudhury, Subir (Inventor); Perry, Jay (Inventor); Walsh, Dennis (Inventor)

    2006-01-01

    A method for regenerable adsorption includes providing a substrate that defines at least one layer of ultra short channel length mesh capable of conducting an electrical current therethrough, coating at least a portion of the substrate with a desired sorbent for trace contaminant control or CO.sub.2 sorption, resistively heating the substrate, and passing a flowstream through the substrate and in contact with the sorbent.

  11. Adsorption of metal ions by carboxymethylchitin and carboxymethylchitosan hydrogels

    NASA Astrophysics Data System (ADS)

    Wasikiewicz, Jaroslaw M.; Nagasawa, Naotsugu; Tamada, Masao; Mitomo, Hiroshi; Yoshii, Fumio

    2005-07-01

    Radiation cross-linking of CM-chitin and CM-chitosan has been investigated. Such parameters of radiation cross-linking as gelation doses, cross-linking and degradation radiation yields and ratios of scission to cross-linking has been determined for both polymers. The absorption ability of various metal ions into EB-radiation cross-linked carboxymethylchitin and carboxymethylchitosan has been investigated. The highest adsorption of scandium and gold has been obtained for carboxymethylchitin (CMCht) and carboxymethylchitosan (CMChts), respectively. Kinetic studies showed that adsorption of most of the metal ions occur in a relatively short period of time (2 h). Detail investigation of adsorption of gold ions has been carried out for both hydrogels. The maximum uptake of Au cations, based on Langmuir equation was determined to be 37.59 for CM-chitosan and 11.86 for CM-chitin. Both hydrogels indicate favorable adsorption of gold cations.

  12. The Yellowstone Fires as Observed by SIR-C SAR

    NASA Technical Reports Server (NTRS)

    Rignot, Eric; Despain, Don; Holecz, Francesco

    1996-01-01

    Covers SIR-C (Spaceborne Imaging Radar C) SAR (Synthetic Aperture Radar) imaging of the 1988 Yellowstone National Forest fires. Discusses some of the images and data collected, and some conclusions drawn from them about both the fires, and SIR-C SAR imaging capabilities.

  13. (Q)SAR: A Tool for the Toxicologist.

    PubMed

    Steinbach, Thomas; Gad-McDonald, Samantha; Kruhlak, Naomi; Powley, Mark; Greene, Nigel

    2015-01-01

    A continuing education (CE) course at the 2014 American College of Toxicology annual meeting covered the topic of (Quantitative) Structure-Activity Relationships [(Q)SAR]. The (Q)SAR methodologies use predictive computer modeling based on predefined rules to describe the relationship between chemical structure and a chemical's associated biological activity or statistical tools to find correlations between biologic activity and the molecular structure or properties of a compound. The (Q)SAR has applications in risk assessment, drug discovery, and regulatory decision making. Pressure within industry to reduce the cost of drug development and societal pressure for government regulatory agencies to produce more accurate and timely risk assessment of drugs and chemicals have necessitated the use of (Q)SAR. Producing a high-quality (Q)SAR model depends on many factors including the choice of statistical methods and descriptors, but first and foremost the quality of the data input into the model. Understanding how a (Q)SAR model is developed and applied is critical to the successful use of such a tool. The CE session covered the basic principles of (Q)SAR, practical applications of these computational models in toxicology, how regulatory agencies use and interpret (Q)SAR models, and potential pitfalls of using them.

  14. An Adaptive Ship Detection Scheme for Spaceborne SAR Imagery.

    PubMed

    Leng, Xiangguang; Ji, Kefeng; Zhou, Shilin; Xing, Xiangwei; Zou, Huanxin

    2016-01-01

    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. PMID:27563902

  15. Web-GIS-based SARS epidemic situation visualization

    NASA Astrophysics Data System (ADS)

    Lu, Xiaolin

    2004-03-01

    In order to research, perform statistical analysis and broadcast the information of SARS epidemic situation according to the relevant spatial position, this paper proposed a unified global visualization information platform for SARS epidemic situation based on Web-GIS and scientific virtualization technology. To setup the unified global visual information platform, the architecture of Web-GIS based interoperable information system is adopted to enable public report SARS virus information to health cure center visually by using the web visualization technology. A GIS java applet is used to visualize the relationship between spatial graphical data and virus distribution, and other web based graphics figures such as curves, bars, maps and multi-dimensional figures are used to visualize the relationship between SARS virus tendency with time, patient number or locations. The platform is designed to display the SARS information in real time, simulate visually for real epidemic situation and offer an analyzing tools for health department and the policy-making government department to support the decision-making for preventing against the SARS epidemic virus. It could be used to analyze the virus condition through visualized graphics interface, isolate the areas of virus source, and control the virus condition within shortest time. It could be applied to the visualization field of SARS preventing systems for SARS information broadcasting, data management, statistical analysis, and decision supporting.

  16. Wave retrieval from SAR imagery in the East China Sea

    NASA Astrophysics Data System (ADS)

    Lou, Xiulin; Chang, Junfang; Liu, Xiaoyan

    2015-12-01

    Synthetic aperture radar (SAR) plays an important role in measuring directional ocean wave spectra with continuous and global coverage. In this article, satellite SAR images were used to estimate the wave parameters in the East China Sea. The Max-Planck Institut (MPI) method was applied to retrieve directional wave spectra from the SAR imagers with the Simulating WAves Nearshore (SWAN) model data as the first guess wave spectra. In order to validate the SAR retrieved wave spectra, a set of buoy measurements during the SAR imaging times was collected and used. The SAR retrieved significant wave heights (SWHs) were analyzed against the buoy measurements to assess the wave retrieval of this study. The root-mean-square error between the SAR SWHs and the buoy measurements is 0.25 m, which corresponds to a relative error of 12%. The case study here shows that the SWAN model data is a potential first guess wave spectra source to the MPI method to retrieve ocean wave spectra from SAR imagery.

  17. Fully polarimetric data from the ARL RailSAR

    NASA Astrophysics Data System (ADS)

    Ranney, Kenneth; Kirose, Getachew; Phelan, Brian; Sherbondy, Kelly

    2016-05-01

    The U.S. Army Research Laboratory (ARL) has recently upgraded the indoor, rail-mounted synthetic aperture radar (SAR) system, RailSAR, to enable collection of large amounts of low-frequency, ultrawideband (UWB) data. Our intent is to provide a research tool that is capable of emulating airborne SAR configuration and associated data collection geometries against surrogate explosive hazard threat deployments. By having such a capability, ARL's facility will afford a more rapid response to the ever changing improvised characteristics associated with explosive hazards today and in the future. Therefore, upgrades to this RailSAR tool to improve functionality and performance are needed to meet the potential rapid response assessments to be carried out. The new, lighter RailSAR cart puts less strain on the radar positioning hardware and allows the system to move smoothly along a specified portion of the rail. In previous papers, we have presented co-polarized SAR data collected using the ARL RailSAR. Recently, however, researchers at ARL have leveraged this asset to collect polarimetric data against multiple targets. This paper presents the SAR imagery resulting from these experiments and documents characteristics of certain target signatures that should be of interest to developers of automatic target detection (ATD) algorithms.

  18. An Adaptive Ship Detection Scheme for Spaceborne SAR Imagery

    PubMed Central

    Leng, Xiangguang; Ji, Kefeng; Zhou, Shilin; Xing, Xiangwei; Zou, Huanxin

    2016-01-01

    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. PMID:27563902

  19. A short note on calculating the adjusted SAR index

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple algebraic technique is presented for computing the adjusted SAR Index proposed by Suarez (1981). The statistical formula presented in this note facilitates the computation of the adjusted SAR without the use of either a look-up table, custom computer software or the need to compute exact a...

  20. Agricultural Performance Monitoring with Polarimetric SAR and Optical Imagery

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  1. Synthetic aperture design for increased SAR image rate

    DOEpatents

    Bielek, Timothy P.; Thompson, Douglas G.; Walker, Bruce C.

    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.

  2. An Adaptive Ship Detection Scheme for Spaceborne SAR Imagery.

    PubMed

    Leng, Xiangguang; Ji, Kefeng; Zhou, Shilin; Xing, Xiangwei; Zou, Huanxin

    2016-08-23

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

  3. [Effect of SDS on the adsorption of Cd2+ onto amphoteric modified bentonites].

    PubMed

    Wang, Jian-Tao; Meng, Zhao-Fu; Yang, Ya-Ti; Yang, Shu-Ying; Li, Bin; Xu, Shao-e

    2014-07-01

    Under different modified ratios, temperatures, pH and ionic strengths, the effect of sodium dodecyl sulfonate (SDS) on the adsorption of Cd2+ onto bentonites which modified with amphoteric modifier dodecyl dimethyl betaine (BS-12) was studied by batch experiments, and the adsorption mechanism was also discussed. Results showed that the adsorption of Cd2+ on amphoteric bentonites can be enhanced significantly by SDS combined modification, Cd2+ adsorption decreases in the order: BS + 150SDS (BS-12 + 150% SDS) > BS + 100SDS (BS-12 + 100% SDS) > BS +50SDS(BS-12 + 50% SDS) > BS + 25SDS (BS-12 + 25% SDS) > BS (BS-12) > CK (unmodified soil). The adsorption isotherm can be described by the Langmuir equation. The change of temperature effect from positive on CK and amphoteric bentonites to negative on BS + 150SDS bentonites is observed with an increase of SDS modified ratio. The pH has little influence on Cd2+ adsorption on bentonites. The adsorption of Cd2+ on bentonites decreases with ionic strength rise, but the effect of ionic strength can be reduced with an increase of SDS modified ratio also. The adsorption thermodynamic parameters demonstrated that the adsorption of Cd2+ on modified bentonites was spontaneously controlled by entropy increment. When the SDS modified ratio is lower than 100% CEC, the adsorption of Cd2+ on modified bentonites is a process with characteristics of both enthalpy increment and entropy increment, while the SDS modified ratio is equal to or higher than 100% CEC, the adsorption of Cd2+ on modified bentonites becomes a process of enthalpy decrement and entropy increment. PMID:25244843

  4. InSAR Scientific Computing Environment (Invited)

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    The InSAR Scientific Computing Environment (ISCE) is a new development effort within the NASA Advanced Information Systems and Technology program, with the intent of recasting the JPL/Caltech ROI_PAC repeat-pass interferometry package into a modern, reconfigurable, open-source computing environment. The new capability initiates the next generation of geodetic imaging processing technology for InSAR sensors, providing flexibility and extensibility in reducing measurements from radar satellites and aircraft to new geophysical products. The NRC Decadal Survey recommended DESDynI mission will deliver to the science community data of unprecedented quantity and quality, making possible global-scale studies in climate research, natural hazards, and Earth’s ecosystem. DESDynI will provide time series and multi-image measurements that permit four-dimensional models of Earth surface processes so that, for example, climate-induced changes over time become apparent and quantifiable. In this paper, we describe the Environment, and illustrate how it can facility space-based geodesy from InSAR. The ISCE invokes object oriented scripts to control legacy and new codes, and abstracts and generalizes the data model for efficient manipulation of objects among modules. The module interfaces are suitable for command-line execution or GUI-programming. It exposes users gradually to its levels of capability, allowing novices to apply it readily for simple tasks and for experienced users to mine the data with great facility. The intent of the effort is to encourage user contributions to the code, creating an open source community that will extend its life and utility.

  5. Evaluation of DEM-assisted SAR coregistration

    NASA Astrophysics Data System (ADS)

    Nitti, D. O.; Hanssen, R. F.; Refice, A.; Bovenga, F.; Milillo, G.; Nutricato, R.

    2008-10-01

    Image alignment is without doubt the most crucial step in SAR Interferometry. Interferogram formation requires images to be coregistered with an accuracy of better than 1/8 pixel to avoid significant loss of phase coherence. Conventional interferometric precise coregistration methods for full-resolution SAR data (Single-Look Complex imagery, or SLC) are based on the cross-correlation of the SLC data, either in the original complex form or as squared amplitudes. Offset vectors in slant range and azimuth directions are computed on a large number of windows, according to the estimated correlation peaks. Then, a two-dimensional polynomial of a certain degree is usually chosen as warp function and the polynomial parameters are estimated through LMS fit from the shifts measured on the image windows. In case of rough topography and long baselines, the polynomial approximation for the warp function becomes inaccurate, leading to local misregistrations. Moreover, these effects increase with the spatial resolution and then with the sampling frequency of the sensor, as first results on TerraSAR-X interferometry confirm. An improved, DEM-assisted image coregistration procedure can be adopted for providing higher-order prediction of the offset vectors. Instead of estimating the shifts on a limited number of patches and using a polynomial approximation for the transformation, this approach computes pixel by pixel the correspondence between master and slave by using the orbital data and a reference DEM. This study assesses the performance of this approach with respect to the standard procedure. In particular, both analytical relationships and simulations will evaluate the impact of the finite vertical accuracy of the DEM on the final coregistration precision for different radar postings and relative positions of satellites. The two approaches are compared by processing real data at different carrier frequencies and using the interferometric coherence as quality figure.

  6. SAR digital spotlight implementation in MATLAB

    NASA Astrophysics Data System (ADS)

    Dungan, Kerry E.; Gorham, LeRoy A.; Moore, Linda J.

    2013-05-01

    Legacy synthetic aperture radar (SAR) exploitation algorithms were image-based algorithms, designed to exploit complex and/or detected SAR imagery. In order to improve the efficiency of the algorithms, image chips, or region of interest (ROI) chips, containing candidate targets were extracted. These image chips were then used directly by exploitation algorithms for the purposes of target discrimination or identification. Recent exploitation research has suggested that performance can be improved by processing the underlying phase history data instead of standard SAR imagery. Digital Spotlighting takes the phase history data of a large image and extracts the phase history data corresponding to a smaller spatial subset of the image. In a typical scenario, this spotlighted phase history data will contain much fewer samples than the original data but will still result in an alias-free image of the ROI. The Digital Spotlight algorithm can be considered the first stage in a "two-stage backprojection" image formation process. As the first stage in two-stage backprojection, Digital Spotlighting filters the original phase history data into a number of "pseudo"-phase histories that segment the scene into patches, each of which contain a reduced number of samples compared to the original data. The second stage of the imaging process consists of standard backprojection. The data rate reduction offered by Digital Spotlighting improves the computational efficiency of the overall imaging process by significantly reducing the total number of backprojection operations. This paper describes the Digital Spotlight algorithm in detail and provides an implementation in MATLAB.

  7. The SAR of brain penetration for a series of heteroaryl urea FAAH inhibitors.

    PubMed

    Keith, John M; Tichenor, Mark S; Apodaca, Richard L; Xiao, Wei; Jones, William M; Seierstad, Mark; Pierce, Joan M; Palmer, James A; Webb, Michael; Karbarz, Mark J; Scott, Brian P; Wilson, Sandy J; Wennerholm, Michelle L; Rizzolio, Michele; Rynberg, Raymond; Chaplan, Sandra R; Breitenbucher, J Guy

    2016-07-01

    The SAR of brain penetration for a series of heteroaryl piperazinyl- and piperadinyl-urea fatty acid amide hydrolase (FAAH) inhibitors is described. Brain/plasma (B/P) ratios ranging from >4:1 to as low as 0.02:1 were obtained through relatively simple structural changes to various regions of the heteroaryl urea scaffold. It was not possible to predict the degree of central nervous system (CNS) penetration from the volumes of distribution (Vd) obtained from pharmacokinetic (PK) experiments as very high Vds did not correlate with high B/P ratios. Similarly, calculated topological polar surface areas (TPSAs) did not consistently correlate with the degree of brain penetration. The lowest B/P ratios were observed for those compounds that were significantly ionized at physiological pH. However, as this class of compounds inhibits the FAAH enzyme through covalent modification, low B/P ratios did not preclude effective central target engagement.

  8. Cd adsorption onto Anoxybacillus flavithermus: Surface complexation modeling and spectroscopic investigations

    SciTech Connect

    Burnett, Peta-Gaye; Daughney, Christopher J.; Peak, Derek

    2008-06-09

    Several recent studies have applied surface complexation theory to model metal adsorption behaviour onto mesophilic bacteria. However, no investigations have used this approach to characterise metal adsorption by thermophilic bacteria. In this study, we perform batch adsorption experiments to quantify cadmium adsorption onto the thermophile Anoxybacillus flavithermus. Surface complexation models (incorporating the Donnan electrostatic model) are developed to determine stability constants corresponding to specific adsorption reactions. Adsorption reactions and stoichiometries are constrained using spectroscopic techniques (XANES, EXAFS, and ATR-FTIR). The results indicate that the Cd adsorption behaviour of A. flavithermus is similar to that of other mesophilic bacteria. At high bacteria-to-Cd ratios, Cd adsorption occurs by formation of a 1:1 complex with deprotonated cell wall carboxyl functional groups. At lower bacteria-to-Cd ratios, a second adsorption mechanism occurs at pH > 7, which may correspond to the formation of a Cd-phosphoryl, CdOH-carboxyl, or CdOH-phosphoryl surface complex. X-ray absorption spectroscopic investigations confirm the formation of the 1:1 Cd-carboxyl surface complex, but due to the bacteria-to-Cd ratio used in these experiments, other complexation mechanism(s) could not be unequivocally resolved by the spectroscopic data.

  9. Salt Kinematics and InSAR

    NASA Technical Reports Server (NTRS)

    Aftabi, Pedarm; Talbot, hristopher; Fielding, Eric

    2005-01-01

    As part of a long-term attempt to learn how the climatic and tectonic signal interact to shape a steady state mountain monitored displacement of a markers in SE termination and also near the summit of a small viscous salt fountain extruding onto the Central plateau of Iran. The marker displacements relate to the first InSAR interferograms of salt extrusion (980913 to 990620) calculated Earth tides, winds, air pressures and temperatures. In the first documented staking exercise, hammered wooden stakes vertically through the surgical marl (c. 1 Ocm deep) onto the top of crystalline salt. These stakes installed in an irregular array elongate E-W along the c.50 m high cliff marking the effective SE terminus of the glacier at Qum Kuh(Centra1 Iran) ,just to the E of a NE trending river cliff about 40 m high. We merely measured the distances between pairs of stakes with known azimuth about 2 m apart to calculate sub horizontal strain in a small part of Qum Kuh. Stakes moved and micro strains for up to 46 pairs of stakes (p strain= ((lengthl-length2)/1engthl) x 10-1) was calculated for each seven stake epochs and plotted against their azimuth on simplified array maps. The data fit well the sine curves cxpected of the maximum and minimum strain ellipses. The first documented stakes located on the SE where the InSAR image show -1 1 to 0 mm pink to purple, 0 to lOmm purple to blue, and show high activity of salt in low activity area of the InSAR image (980913 to 990620).Short term micro strains of stake tie lines record anisotropic expansions due to heating and contraction due to cooling. All epochs changed between 7 to 1 17 days (990928 to000 1 16), showed 200 to 400 micro strain lengthening and shortening. The contraction and extension existed in each epoch, but the final strain was extension in E-W in Epoch land 6, contraction in E-W direction during epochs 2-3-4-5 and 7. The second pair of stakes hammered about 20 cm deep into the deep soils(more than 1 m) , near summit

  10. Detection of land degradation with polarimetric SAR

    NASA Technical Reports Server (NTRS)

    Ray, Terrill W.; Farr, Tom G.; Van Zyl, Jakob J.

    1992-01-01

    Multispectral radar polarimeter data were collected over the Manix Basin Area of the Mojave desert using an airborne SAR. An analysis of the data reveals unusual polarization responses which are attributed to the formation of wind ripples on the surfaces of fields that have been abandoned for more than 5 years. This hypothesis has been confirmed through field observations, and a second-order perturbation model is shown to effectively model the polarization responses. The results demonstrate the usefulness of remote sensing techniques for the study of land degradation at synoptic scales.

  11. Software For Calibration Of Polarimetric SAR Data

    NASA Technical Reports Server (NTRS)

    Van Zyl, Jakob; Zebker, Howard; Freeman, Anthony; Holt, John; Dubois, Pascale; Chapman, Bruce

    1994-01-01

    POLCAL (Polarimetric Radar Calibration) software tool intended to assist in calibration of synthetic-aperture radar (SAR) systems. In particular, calibrates Stokes-matrix-format data produced as standard product by NASA/Jet Propulsion Laboratory (JPL) airborne imaging synthetic aperture radar (AIRSAR). Version 4.0 of POLCAL is upgrade of version 2.0. New options include automatic absolute calibration of 89/90 data, distributed-target analysis, calibration of nearby scenes with corner reflectors, altitude or roll-angle corrections, and calibration of errors introduced by known topography. Reduces crosstalk and corrects phase calibration without use of ground calibration equipment. Written in FORTRAN 77.

  12. Characterization of a Track-and-Hold Amplifier for Application to a High Performance SAR

    SciTech Connect

    DUBBERT, DALE F.; HARDIN, TERRY LYNN; DELAPLAIN, GILBERT G.

    2002-07-01

    A Synthetic Aperture Radar (SAR) which employs direct IF sampling can significantly reduce the complexity of the analog electronics prior to the analog-to-digital converter (ADC). For relatively high frequency IF bands, a wide-bandwidth track-and-hold amplifier (THA) is required prior to the ADC. The THA functions primarily as a means of converting, through bandpass sampling, the IF signal to a baseband signal which can be sampled by the ADC. For a wide-band, high dynamic-range receiver system, such as a SAR receiver, stringent performance requirements are placed on the THA. We first measure the THA parameters such as gain, gain compression, third-order intercept (TOI), signal-to-noise ratio (SNR), spurious-free dynamic-range (SFDR), noise figure (NF), and phase noise. The results are then analyzed in terms of their respective impact on the overall performance of the SAR. The specific THA under consideration is the Rockwell Scientific RTH010.

  13. The Accuratre Signal Model and Imaging Processing in Geosynchronous SAR

    NASA Astrophysics Data System (ADS)

    Hu, Cheng

    With the development of synthetic aperture radar (SAR) application, the disadvantage of low earth orbit (LEO) SAR becomes more and more apparent. The increase of orbit altitude can shorten the revisit time and enlarge the coverage area in single look, and then satisfy the application requirement. The concept of geosynchronous earth orbit (GEO) SAR system is firstly presented and deeply discussed by K.Tomiyasi and other researchers. A GEO SAR, with its fine temporal resolution, would overcome the limitations of current imaging systems, allowing dense interpretation of transient phenomena as GPS time-series analysis with a spatial density several orders of magnitude finer. Until now, the related literatures about GEO SAR are mainly focused in the system parameter design and application requirement. As for the signal characteristic, resolution calculation and imaging algorithms, it is nearly blank in the related literatures of GEO SAR. In the LEO SAR, the signal model analysis adopts the `Stop-and-Go' assumption in general, and this assumption can satisfy the imaging requirement in present advanced SAR system, such as TerraSAR, Radarsat2 and so on. However because of long propagation distance and non-negligible earth rotation, the `Stop-and-Go' assumption does not exist and will cause large propagation distance error, and then affect the image formation. Furthermore the long propagation distance will result in the long synthetic aperture time such as hundreds of seconds, therefore the linear trajectory model in LEO SAR imaging will fail in GEO imaging, and the new imaging model needs to be proposed for the GEO SAR imaging processing. In this paper, considering the relative motion between satellite and earth during signal propagation time, the accurate analysis method for propagation slant range is firstly presented. Furthermore, the difference between accurate analysis method and `Stop-and-Go' assumption is analytically obtained. Meanwhile based on the derived

  14. Single Baseline Tomography SAR for Forest Above Ground Biomass Estimation

    NASA Astrophysics Data System (ADS)

    Li, Wenmei; Chen, Erxue; Li, Zengyuan; Wang, Xinshuang; Feng, Qi

    2013-01-01

    Single baseline tomography SAR is used for forest height estimation as its little restriction on the number of baselines and configurations of tracks in recent years. There existed two kinds of single baseline tomography SAR techniques, the polarimetric coherence tomography (PCT) and the sum of Kronecker product (SKP), algebraic synthesis (AS) and Capon spectral estimator approach (SKP-AS-Capon). Few researches on forest above ground biomass (AGB) estimation are there using single baseline tomography SAR. In this paper, PCT and SKP-AS-Capon approaches are proposed for forest AGB estimation. L-band data set acquired by E-SAR airborne system in 2003 for the forest test site in Traunstein, is used for this experiment. The result shows that single baseline polarimetric tomography SAR can obtain forest AGB in forest stand scale, and SKP-AS-Capon method has better detailed vertical structure information, while the Freeman 3-component combined PCT approach gets a homogenous vertical structure in forest stand.

  15. [Adsorption characteristics of f2 bacteriophages by four substrates in constructed wetland].

    PubMed

    Chen, Di; Zheng, Xiang; Wei, Yuan-Song; Yang, Yong

    2013-10-01

    Performance of f2 phages adsorption by four substrates including anthracite coal, steel slag, zeolite and forsterite was investigated through batch and dynamic experiments. Results of batch experiments showed that the removal efficiency of f2 phages by these four substrates was in the order of anthracite > steel slag > forsterite approximately zeolite. The adsorption of f2 phages by anthracite experienced fast, medium and slow stages, and the removal efficiency of f2 phages increased gradually with the increase of anthracite dosage, e. g. the optimized dosage of anthracite was 8.0 g at a solid/liquid ratio of 1:12.5 (m/V). The isothermal adsorption of all four substrates was described with Freundlich and Langmuir isothermal adsorption equation very well, and the adsorption of f2 phages by both anthracite and steel slag fitted pseudo-second order adsorption kinetics at their theoretical adsorption capacities of 3. 35 x 10(8) PFU.g-1 and 2.56 x 10(8) PFU.g-1, respectively, nearly the same as the equilibrium adsorption capacities obtained under the experiment conditions. And the liquid diffusion process was a rate-limiting step of the adsorption of f2 phage by both anthracite and steel slag, but not the only one. The results of dynamic adsorption experiments showed that the adsorption process of f2 phages in the three adsorption columns including anthracite, steel slag and zeolite experienced four stages of adaption, adsorption, pulse adsorption and adsorption equilibrium, and the total removal rates of f2 phages were more than 2. 55 Ig.

  16. Comparison and Analysis of Geometric Correction Models of Spaceborne SAR.

    PubMed

    Jiang, Weihao; Yu, Anxi; Dong, Zhen; Wang, Qingsong

    2016-01-01

    Following the development of synthetic aperture radar (SAR), SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD) model, a rational polynomial coefficients (RPC) model, a revised polynomial (PM) model and an elevation derivation (EDM) model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model. PMID:27347973

  17. Comparison and Analysis of Geometric Correction Models of Spaceborne SAR

    PubMed Central

    Jiang, Weihao; Yu, Anxi; Dong, Zhen; Wang, Qingsong

    2016-01-01

    Following the development of synthetic aperture radar (SAR), SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD) model, a rational polynomial coefficients (RPC) model, a revised polynomial (PM) model and an elevation derivation (EDM) model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model. PMID:27347973

  18. Comparison and Analysis of Geometric Correction Models of Spaceborne SAR.

    PubMed

    Jiang, Weihao; Yu, Anxi; Dong, Zhen; Wang, Qingsong

    2016-06-25

    Following the development of synthetic aperture radar (SAR), SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD) model, a rational polynomial coefficients (RPC) model, a revised polynomial (PM) model and an elevation derivation (EDM) model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model.

  19. Internal wave parameters retrieval from space-borne SAR image

    NASA Astrophysics Data System (ADS)

    Fan, Kaiguo; Fu, Bin; Gu, Yanzhen; Yu, Xingxiu; Liu, Tingting; Shi, Aiqin; Xu, Ke; Gan, Xilin

    2015-12-01

    Based on oceanic internal wave SAR imaging mechanism and the microwave scattering imaging model for oceanic surface features, we developed a new method to extract internal wave parameters from SAR imagery. Firstly, the initial wind fields are derived from NCEP reanalysis data, the sea water density and oceanic internal wave pycnocline depth are estimated from the Levites data, the surface currents induced by the internal wave are calculated according to the KDV equation. The NRCS profile is then simulated by solving the action balance equation and using the sea surface radar backscatter model. Both the winds and internal wave pycnocline depth are adjusted by using the dichotomy method step by step to make the simulated data approach the SAR image. Then, the wind speed, pycnocline depth, the phase speed, the group velocity and the amplitude of internal wave can be retrieved from SAR imagery when a best fit between simulated signals and the SAR image appears. The method is tested on one scene SAR image near Dongsha Island, in the South China Sea, results show that the simulated oceanic internal wave NRCS profile is in good agreement with that on the SAR image with the correlation coefficient as high as 90%, and the amplitude of oceanic internal wave retrieved from the SAR imagery is comparable with the SODA data. Besides, the phase speeds retrieved from other 16 scene SAR images in the South China Sea are in good agreement with the empirical formula which describes the relations between internal wave phase speed and water depths, both the root mean square and relative error are less than 0.11 m•s-1 and 7%, respectively, indicating that SAR images are useful for internal wave parameters retrieval and the method developed in this paper is convergent and applicable.

  20. Multi-scale InSAR analysis of aseismic creep across the San Andreas, Calevaras,and Hayward Fault systems

    NASA Astrophysics Data System (ADS)

    Agram, P. S.; Simons, M.

    2011-12-01

    We apply the Multi-scale Interferometric Time-series (MInTS) technique, developed at Caltech,to study spatial variations in aseismic creep across the San Andreas, Calaveras and Hayward Faultsystems in Central California.Interferometric Synthetic Aperture Radar (InSAR) Time-series methods estimate the spatio-temporal evolution of surface deformation using multiple SAR interferograms. Traditional time-series analysis techniques like persistent scatterers and short baseline methods assume the statistical independence of InSAR phase measurements over space and time when estimating deformation. However, existing atmospheric phase screen models clearly show that noise in InSAR phase observations is correlated over the spatial domain. MInTS is an approach designed to exploit the correlation of phase observations over space to significantly improve the signal-to-noise ratio in the estimated deformation time-series compared to the traditional time-series InSAR techniques. The MInTS technique reduces the set of InSAR observations to a set of almost uncorrelated observations at various spatial scales using wavelets. Traditional inversion techniques can then be applied to the wavelet coefficients more effectively. Creep across the Central San Andreas Fault and the Hayward Fault has been studied previously using C-band (6 cm wavelength) ERS data, but detailed analysis of the transition zone between the San Andreas and Hayward Faults was not possible due to severe decorrelation. Improved coherence at L-band (24 cm wavelength) significantly improves the spatial coverage of the estimated deformation signal in our ALOS PALSAR data set. We analyze 450 ALOS PALSAR interferograms processed using 175 SAR images acquired between Dec 2006 and Dec 2010 that cover the area along the San Andreas Fault System from Richmond in the San Francisco Bay Area to Maricopa in the San Joaquin Valley.We invert the InSAR phase observations to estimate the constant Line-of-Sight (LOS) deformation

  1. Estimation of Biomass Carbon Stocks over Peat Swamp Forests using Multi-Temporal and Multi-Polratizations SAR Data

    NASA Astrophysics Data System (ADS)

    Wijaya, A.; Liesenberg, V.; Susanti, A.; Karyanto, O.; Verchot, L. V.

    2015-04-01

    The capability of L-band radar backscatter to penetrate through the forest canopy is useful for mapping the forest structure, including above ground biomass (AGB) estimation. Recent studies confirmed that the empirical AGB models generated from the L-band radar backscatter can provide favourable estimation results, especially if the data has dual-polarization configuration. Using dual polarimetry SAR data the backscatter signal is more sensitive to forest biomass and forest structure because of tree trunk scattering, thus showing better discriminations of different forest successional stages. These SAR approaches, however, need to be further studied for the application in tropical peatlands ecosystem We aims at estimating forest carbon stocks and stand biophysical properties using combination of multi-temporal and multi-polarizations (quad-polarimetric) L-band SAR data and focuses on tropical peat swamp forest over Kampar Peninsula at Riau Province, Sumatra, Indonesia which is one of the most peat abundant region in the country. Applying radar backscattering (Sigma nought) to model the biomass we found that co-polarizations (HH and VV) band are more sensitive than cross-polarization channels (HV and VH). Individual HH polarization channel from April 2010 explained > 86% of AGB. Whereas VV polarization showed strong correlation coefficients with LAI, tree height, tree diameter and basal area. Surprisingly, polarimetric anisotropy feature from April 2007 SAR data show relatively high correlations with almost all forest biophysical parameters. Polarimetric anisotropy, which explains the ratio between the second and the first dominant scattering mechanism from a target has reduced at some extent the randomness of scattering mechanism, thus improve the predictability of this particular feature in estimating the forest properties. These results may be influenced by local seasonal variations of the forest as well as moisture, but available quad-pol SAR data were unable to

  2. An introduction to the interim digital SAR processor and the characteristics of the associated Seasat SAR imagery

    NASA Technical Reports Server (NTRS)

    Wu, C.; Barkan, B.; Huneycutt, B.; Leang, C.; Pang, S.

    1981-01-01

    Basic engineering data regarding the Interim Digital SAR Processor (IDP) and the digitally correlated Seasat synthetic aperature radar (SAR) imagery are presented. The correlation function and IDP hardware/software configuration are described, and a preliminary performance assessment presented. The geometric and radiometric characteristics, with special emphasis on those peculiar to the IDP produced imagery, are described.

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

    ERIC Educational Resources Information Center

    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…

  4. Discrimination of crop types with TerraSAR-X-derived information

    NASA Astrophysics Data System (ADS)

    Sonobe, Rei; Tani, Hiroshi; Wang, Xiufeng; Kobayashi, Nobuyuki; Shimamura, Hideki

    Although classification maps are required for management and for the estimation of agricultural disaster compensation, those techniques have yet to be established. This paper describes the comparison of three different classification algorithms for mapping crops in Hokkaido, Japan, using TerraSAR-X (including TanDEM-X) dual-polarimetric data. In the study area, beans, beets, grasslands, maize, potatoes and winter wheat were cultivated. In this study, classification using TerraSAR-X-derived information was performed. Coherence values, polarimetric parameters and gamma nought values were also obtained and evaluated regarding their usefulness in crop classification. Accurate classification may be possible with currently existing supervised learning models. A comparison between the classification and regression tree (CART), support vector machine (SVM) and random forests (RF) algorithms was performed. Even though J-M distances were lower than 1.0 on all TerraSAR-X acquisition days, good results were achieved (e.g., separability between winter wheat and grass) due to the characteristics of the machine learning algorithm. It was found that SVM performed best, achieving an overall accuracy of 95.0% based on the polarimetric parameters and gamma nought values for HH and VV polarizations. The misclassified fields were less than 100 a in area and 79.5-96.3% were less than 200 a with the exception of grassland. When some feature such as a road or windbreak forest is present in the TerraSAR-X data, the ratio of its extent to that of the field is relatively higher for the smaller fields, which leads to misclassifications.

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

    NASA Technical Reports Server (NTRS)

    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; Lu, Daniel

    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).

  6. Rapid inactivation of SARS-like coronaviruses.

    SciTech Connect

    Kapil, Sanjay; Oberst, R. D.; Bieker, Jill Marie; Tucker, Mark David; Souza, Caroline Ann; Williams, Cecelia Victoria

    2004-03-01

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

  7. Ultrawideband VHF SAR design and measurements

    NASA Astrophysics Data System (ADS)

    Hellsten, Hans; Froelind, Per-Olov; Gustafsson, Anders; Jonsson, T.; Larsson, Bjoern; Stenstroem, Gunnar; Binder, Bradley T.; Mirkin, Mitchell I.; Ayasli, Serpil

    1994-07-01

    CARABAS, an acronym for `coherent all radio band sensing,' is an airborne, horizontal-polarization SAR operating across the frequency band 20 to 90 MHz, conceived, designed and built by FOA in Sweden. The original motivation for designing such a low frequency system was that a large relative or fractional bandwidth could be achieved at low frequencies. For reasons to be explained, a large fractional bandwidth was considered to be of potential benefit for radar detection in severe clutter environments. A feasibility study of a short wave ultra-wideband radar started at FOA in 1985. Actual construction of the CARABAS system commenced 1987, aircraft integration took place during 1991 and the first radar tests were conducted in early 1992. From the fall of 1992 onwards, field campaigns and evaluation studies have been conducted as a joint effort between FOA and MIT Lincoln Laboratory in the US. This article will focus on experiences concerning foliage penetration with the system. First we touch upon the CARABAS system characteristics, outline the arguments behind a large fractional bandwidth VHF-band SAR approach to foliage penetration, and finally present some early experimental results. We refer to other papers for a fuller explanation of the system, for more details of image calibration, and for results concerning underground imaging.

  8. SAR Image despeckling via sparse representation

    NASA Astrophysics Data System (ADS)

    Wang, Zhongmei; Yang, Xiaomei; Zheng, Liang

    2014-11-01

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

  9. Classification SAR targets with support vector machine

    NASA Astrophysics Data System (ADS)

    Cao, Lanying

    2007-02-01

    With the development of Synthetic Aperture Radar (SAR) technology, automatic target recognition (ATR) is becoming increasingly important. In this paper, we proposed a 3-class target classification system in SAR images. The system is based on invariant wavelet moments and support vector machine (SVM) algorithm. It is a two-stage approach. The first stage is to extract and select a small set of wavelet invariant moment features to indicate target images. The wavelet invariant moments take both advantages of the wavelet inherent property of multi-resolution analysis and moment invariants quality of invariant to translation, scaling changes and rotation. The second stage is classification of targets with SVM algorithm. SVM is based on the principle of structural risk minimization (SRM), which has been shown better than the principle of empirical risk minimization (ERM) which is used by many conventional networks. To test the performance and efficiency of the proposed method, we performed experiments on invariant wavelet moments, different kernel functions, 2-class identification, and 3-class identification. Test results show that wavelet invariant moments indicate the target effectively; linear kernel function achieves better results than other kernel functions, and SVM classification approach performs better than conventional nearest distance approach.

  10. Fundamental SAR ATR performance predictions for design trade-offs: 1D HRR versus 2D SAR versus 3D SAR

    NASA Astrophysics Data System (ADS)

    Horowitz, Larry L.; Brendel, Gary F.

    1999-08-01

    This paper continues the development of a fundamental, algorithm-independent view of the ATR performance that can be achieved using SAR data. Such ATR performance predictions are intended to enable evaluation of performance tradeoffs for SAR designs, including both parameter selections (e.g., bandwidth and transmit power) and added domains of SAR observation, such as 3-D, full polarimetry, aspect diversity, and/or frequency diversity. Using a Bayesian framework, we show target classification performance predictions for two tactical targets (either stationary with radar netting assumed deployed, or moving) using three different domains of observation: 1-D HRR (high-range-resolution radar), 2-D SAR, and 3-D SAR. Comparisons of the three domains are made at 3m, 1m, 0.5m and 0.3m range and cross-range resolutions. The discussion of 3-D SAR includes parameter tradeoffs of various height resolutions at the target, and various numbers of sensors. For each measurement modality, we list some of the unique sensitivities which could cause performance degradations.

  11. A 100 MS/s 9 bit 0.43 mW SAR ADC with custom capacitor array

    NASA Astrophysics Data System (ADS)

    Jingjing, Wang; Zemin, Feng; Rongjin, Xu; Chixiao, Chen; Fan, Ye; Jun, Xu; Junyan, Ren

    2016-05-01

    A low power 9 bit 100 MS/s successive approximation register analog-to-digital converter (SAR ADC) with custom capacitor array is presented. A brand-new 3-D MOM unit capacitor is used as the basic capacitor cell of this capacitor array. The unit capacitor has a capacitance of 1 fF. Besides, the advanced capacitor array structure and switch mode decrease the power consumption a lot. To verify the effectiveness of this low power design, the 9 bit 100 MS/s SAR ADC is implemented in TSMC IP9M 65 nm LP CMOS technology. The measurement results demonstrate that this design achieves an effective number of bits (ENOB) of 7.4 bit, a signal-to-noise plus distortion ratio (SNDR) of 46.40 dB and a spurious-free dynamic range (SFDR) of 62.31 dB at 100 MS/s with 1 MHz input. The SAR ADC core occupies an area of 0.030 mm2 and consumes 0.43 mW under a supply voltage of 1.2 V. The figure of merit (FOM) of the SAR ADC achieves 23.75 fJ/conv. Project supported by the National High-Tech Research and Development Program of China (No. 2013AA014101).

  12. A 12-bit 1 MS/s SAR-ADC for multi-channel CdZnTe detectors

    NASA Astrophysics Data System (ADS)

    Wei, Liu; Tingcun, Wei; Bo, Li; Panjie, Guo; Yongcai, Hu

    2015-04-01

    This paper presents a low power, area-efficient and radiation-hardened 12-bit 1 MS/s successive approximation register (SAR) analog-to-digital converter (ADC) for multi-channel CdZnTe (CZT) detector applications. In order to improve the SAR-ADC's accuracy, a novel comparator is proposed in which the offset voltage is self-calibrated and also a new architecture for the unit capacitor array is proposed to reduce the capacitance mismatches in the charge-redistribution DAC. The ability to radiation-harden the SAR-ADC is enhanced through circuit and layout design technologies. The prototype chip was fabricated using a TSMC 0.35 μm 2P4M CMOS process. At a 3.3/5 V power supply and a sampling rate of 1 MS/s, the proposed SAR-ADC achieves a peak signal to noise and distortion ratio (SINAD) of 67.64 dB and consumes only 10 mW power. The core of the prototype chip occupies an active area of 1180 × 1080 μm2. Project supported by the Special-Funded Program on National Key Scientific Instruments and Equipment Development (No. 2011YQ040082).

  13. The significant wave height estimation by the azimuth cutoff of the quad-polarization SAR image

    NASA Astrophysics Data System (ADS)

    Ren, Lin; Yang, Jingsong; Zheng, Gang; Wang, Juan

    2014-11-01

    This paper primarily proposes simple C-band empirical models between ocean wave significant wave height (Hs) and SAR azimuth cutoff using RADARSAT-2 fine quad-polarization mode data. The empirical models of VV, HH and VH polarization relate the Hs to the cutoff divided by range-velocity-ratio with approximatly linear relationships. Compared from NDBC buoy data, retrieved Hs by empirical models have the root mean square (Rms) errors of 0.62 m, 0.52 m and 0.70 m for VV, HH and VH polarization, respectively. Particularly, HH polarization presents the best Hs retrieval performance.

  14. A New Maximum-Likelihood Change Estimator for Two-Pass SAR Coherent Change Detection.

    SciTech Connect

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

    2014-09-01

    In this paper, we derive a new optimal change metric to be used in synthetic aperture RADAR (SAR) coherent change detection (CCD). Previous CCD methods tend to produce false alarm states (showing change when there is none) in areas of the image that have a low clutter-to-noise power ratio (CNR). The new estimator does not suffer from this shortcoming. It is a surprisingly simple expression, easy to implement, and is optimal in the maximum-likelihood (ML) sense. The estimator produces very impressive results on the CCD collects that we have tested.

  15. SAR imaging via modern 2-D spectral estimation methods.

    PubMed

    DeGraaf, S R

    1998-01-01

    This paper discusses the use of modern 2D spectral estimation algorithms for synthetic aperture radar (SAR) imaging. The motivation for applying power spectrum estimation methods to SAR imaging is to improve resolution, remove sidelobe artifacts, and reduce speckle compared to what is possible with conventional Fourier transform SAR imaging techniques. This paper makes two principal contributions to the field of adaptive SAR imaging. First, it is a comprehensive comparison of 2D spectral estimation methods for SAR imaging. It provides a synopsis of the algorithms available, discusses their relative merits for SAR imaging, and illustrates their performance on simulated and collected SAR imagery. Some of the algorithms presented or their derivations are new, as are some of the insights into or analyses of the algorithms. Second, this work develops multichannel variants of four related algorithms, minimum variance method (MVM), reduced-rank MVM (RRMVM), adaptive sidelobe reduction (ASR) and space variant apodization (SVA) to estimate both reflectivity intensity and interferometric height from polarimetric displaced-aperture interferometric data. All of these interferometric variants are new. In the interferometric contest, adaptive spectral estimation can improve the height estimates through a combination of adaptive nulling and averaging. Examples illustrate that MVM, ASR, and SVA offer significant advantages over Fourier methods for estimating both scattering intensity and interferometric height, and allow empirical comparison of the accuracies of Fourier, MVM, ASR, and SVA interferometric height estimates.

  16. Synthetic aperture radar speckle reduction for circle mode SAR images

    NASA Astrophysics Data System (ADS)

    Musgrove, Cameron

    2016-05-01

    Synthetic aperture radar (SAR) images contain a grainy pattern, called speckle, that is a consequence of a coherent imaging system. For fine resolution SAR images speckle can obscure subtle features and reduce visual appeal. Many speckle reduction methods result in a loss of image resolution and reduce visual appeal which can obscure subtle features. Another approach to maintain resolution while reducing speckle is to register and combine multiple images. For persistent surveillance applications it is more efficient for an airborne platform to fly circles around the particular area of interest. In these cases, it would be beneficial to combine multiple circle mode SAR images, however the image registration process is not so straightforward because the layover angle changes in each image. This paper develops a SAR image registration process for combining multiple circle mode SAR images to reduce speckle while preserving resolution. The registration first uses a feature matching algorithm for a coarse rotation and alignment, and then uses a fine registration and warp. Ku band SAR data from a circle mode SAR collection is used to show the effectiveness of the registration and enhanced visual appeal from multi-looking.

  17. SARS Grid--an AG-based disease management and collaborative platform.

    PubMed

    Hung, Shu-Hui; Hung, Tsung-Chieh; Juang, Jer-Nan

    2006-01-01

    This paper describes the development of the NCHC's Severe Acute Respiratory Syndrome (SARS) Grid project-An Access Grid (AG)-based disease management and collaborative platform that allowed for SARS patient's medical data to be dynamically shared and discussed between hospitals and doctors using AG's video teleconferencing (VTC) capabilities. During the height of the SARS epidemic in Asia, SARS Grid and the SARShope website significantly curved the spread of SARS by helping doctors manage the in-hospital and in-home care of quarantined SARS patients through medical data exchange and the monitoring of the patient's symptoms. Now that the SARS epidemic has ended, the primary function of the SARS Grid project is that of a web-based informatics tool to increase pubic awareness of SARS and other epidemic diseases. Additionally, the SARS Grid project can be viewed and further studied as an outstanding model of epidemic disease prevention and/or containment.

  18. Ground Displacement Measurement of the 2013 Balochistan Earthquake with interferometric TerraSAR-X ScanSAR data

    NASA Astrophysics Data System (ADS)

    Yague-Martinez, N.; Fielding, E. J.; Haghshenas-Haghighi, M.; Cong, X.; Motagh, M.

    2014-12-01

    This presentation will address the 24 September 2013 Mw 7.7 Balochistan Earthquake in western Pakistan from the point of view of interferometric processing algorithms of wide-swath TerraSAR-X ScanSAR images. The algorithms are also valid for TOPS acquisition mode, the operational mode of the Sentinel-1A ESA satellite that was successfully launched in April 2014. Spectral properties of burst-mode data and an overview of the interferometric processing steps of burst-mode acquisitions, emphasizing the importance of the co-registration stage, will be provided. A co-registration approach based on incoherent cross-correlation will be presented and applied to seismic scenarios. Moreover geodynamic corrections due to differential atmospheric path delay and differential solid Earth tides are considered to achieve accuracy in the order of several centimeters. We previously derived a 3D displacement map using cross-correlation techniques applied to optical images from Landsat-8 satellite and TerraSAR-X ScanSAR amplitude images. The Landsat-8 cross-correlation measurements cover two horizontal directions, and the TerraSAR-X displacements include both horizontal along-track and slant-range (radar line-of-sight) measurements that are sensitive to vertical and horizontal deformation. It will be justified that the co-seismic displacement map from TerraSAR-X ScanSAR data may be contaminated by postseismic deformation due to the fact that the post-seismic acquisition took place one month after the main shock, confirmed in part by a TerraSAR-X stripmap interferogram (processed with conventional InSAR) covering part of the area starting on 27 September 2013. We have arranged the acquisition of a burst-synchronized stack of TerraSAR-X ScanSAR images over the affected area after the earthquake. It will be possible to apply interferometry to these data to measure the lower magnitude of the expected postseismic displacements. The processing of single interferograms will be discussed. A

  19. Retrieval of the thickness of undeformed sea ice from simulated C-band compact polarimetric SAR images

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Dierking, Wolfgang; Zhang, Jie; Meng, Junmin; Lang, Haitao

    2016-07-01

    In this paper we introduce a parameter for the retrieval of the thickness of undeformed first-year sea ice that is specifically adapted to compact polarimetric (CP) synthetic aperture radar (SAR) images. The parameter is denoted as the "CP ratio". In model simulations we investigated the sensitivity of the CP ratio to the dielectric constant, ice thickness, ice surface roughness, and radar incidence angle. From the results of the simulations we deduced optimal sea ice conditions and radar incidence angles for the ice thickness retrieval. C-band SAR data acquired over the Labrador Sea in circular transmit and linear receive (CTLR) mode were generated from RADARSAT-2 quad-polarization images. In comparison with results from helicopter-borne measurements, we tested different empirical equations for the retrieval of ice thickness. An exponential fit between the CP ratio and ice thickness provides the most reliable results. Based on a validation using other compact polarimetric SAR images from the same region, we found a root mean square (rms) error of 8 cm and a maximum correlation coefficient of 0.94 for the retrieval procedure when applying it to level ice between 0.1 and 0.8 m thick.

  20. Multisite adsorption of cadmium on goethite

    SciTech Connect

    Venema, P.; Hiemstra, T.; Riemsdijk, W.H. van

    1996-11-10

    Recently a new general ion adsorption model has been developed for ion binding to mineral surfaces (Hiemstra and van Riemsdijk, 1996). The model uses the Pauling concept of charge distribution (CD) and is an extension of the multi-site complexation (MUSIC) approach. In the CD-MUSIC model the charge of an adsorbing ion that forms an inner sphere complex is distributed over its ligands, which are present in two different electrostatic planes. In this paper the authors have applied the CD-MUSIC model to the adsorption of metal cations, using an extended data set for cadmium adsorbing on goethite. The adsorption of cadmium and the cadmium-proton exchange ratio were measured as function of metal ion concentration, pH, and ionic strength. The data could be described well, taking into account the surface heterogeneity resulting from the presence of two different crystal planes (the dominant 110 face and the minor 021 face). The surface species used in the model are consistent with recent EXAFS data. In accordance with the EXAFS results, high-affinity complexes at the 021 face were used in the model.

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

    PubMed

    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.

  2. Indoor experimental facility for airborne synthetic aperture radar (SAR) configurations - rail-SAR

    NASA Astrophysics Data System (ADS)

    Kirose, Getachew; Phelan, Brian R.; Sherbondy, Kelly D.; Ranney, Kenneth I.; Koenig, Francois; Narayanan, Ram M.

    2014-05-01

    The Army Research Laboratory (ARL) is developing an indoor experimental facility to evaluate and assess airborne synthetic-aperture-radar-(SAR)-based detection capabilities. The rail-SAR is located in a multi-use facility that also provides a base for research and development in the area of autonomous robotic navigation. Radar explosive hazard detection is one key sensordevelopment area to be investigated at this indoor facility. In particular, the mostly wooden, multi-story building houses a two (2) story housing structure and an open area built over a large sandbox. The housing structure includes reconfigurable indoor walls which enable the realization of multiple See-Through-The-Wall (STTW) scenarios. The open sandbox, on the other hand, allows for surface and buried explosive hazard scenarios. The indoor facility is not rated for true explosive hazard materials so all targets will need to be inert and contain surrogate explosive fills. In this paper we discuss the current system status and describe data collection exercises conducted using canonical targets and frequencies that may be of interest to designers of ultra-wideband (UWB) airborne, ground penetrating SAR systems. A bi-static antenna configuration will be used to investigate the effects of varying airborne SAR parameters such as depression angle, bandwidth, and integration angle, for various target types and deployment scenarios. Canonical targets data were used to evaluate overall facility capabilities and limitations. These data is analyzed and summarized for future evaluations. Finally, processing techniques for dealing with RF multi-path and RFI due to operating inside the indoor facility are described in detail. Discussion of this facility and its capabilities and limitations will provide the explosive hazard community with a great airborne platform asset for sensor to target assessment.

  3. Adsorption characteristics of brush polyelectrolytes on silicon oxynitride revealed by dual polarization interferometry.

    PubMed

    Bijelic, Goran; Shovsky, Alexander; Varga, Imre; Makuska, Ricardas; Claesson, Per M

    2010-08-01

    Adsorption properties of bottle-brush polyelectrolytes have been investigated using dual polarization interferometry (DPI), which provides real time monitoring of adsorbed layer thickness and refractive index. The adsorption on silicon oxynitride was carried out from aqueous solution with no added inorganic salt, and the adsorbed polyelectrolyte layer was subsequently rinsed with NaCl solutions of increasing concentration. The bottle-brush polyelectrolytes investigated in this study have different ratios of permanent cationic charged segments and uncharged PEO side chains. Both the cationic groups and the PEO side chains have affinity for silica-like surfaces, and thus contribute to the adsorption process that becomes rather complex. Adsorption properties in water, responses to changes in ionic strength of the surrounding medium, adsorption kinetics and the layer structure are all strongly dependent on the ratio between backbone charges and side chains. The results are interpreted in terms of competitive adsorption of segments with different chemical nature. The adsorption kinetics is relatively fast, taking only tens to hundreds of seconds when adsorbed from dilute 100 ppm solutions. The DPI technique was found to be suitable for studying such rapid adsorption processes, including determination of the initial adsorption kinetics. We expect that the effects observed in this study are of general importance for synthetic and biological polymers carrying segments of different nature.

  4. Cd adsorption onto bacterial surfaces: A universal adsorption edge?

    NASA Astrophysics Data System (ADS)

    Yee, Nathan; Fein, Jeremy

    2001-07-01

    In this study, we measure the thermodynamic stability constants for proton and Cd binding onto the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, and the Gram-positive bacteria Bacillus megaturium, Streptococcus faecalis, Staphylococcus aureus, Sporosarcina ureae, and Bacillus cereus. Potentiometric titrations and Cd-bacteria adsorption experiments yield average values for the carboxyl site pK a, site concentration, and log stability constant for the bacterial surface Cd-carboxyl complex of 5.0, 2.0 × 10 -3 mol/g and 4.0 respectively. Our results indicate that a wide range of bacterial species exhibit nearly identical Cd adsorption behavior as a function of pH. We propose that metal-bacteria adsorption is not dependent on the bacterial species involved, and we develop a generalized adsorption model which may greatly simplify the task of quantifying the effects of bacterial adsorption on dissolved mass transport in realistic geologic systems.

  5. Rethinking Critical Adsorption

    NASA Astrophysics Data System (ADS)

    Franck, Carl; Peach, Sarah; Polak, Robert D.

    1996-03-01

    Recent reflectivity experiments on near-critical mixtures of carbon disulfide and nitromethane contained in glass cells footnote Niraj S. Desai, Sarah Peach, and Carl Franck, Phys. Rev. E 52, 4129 (1995) have shown that preferential adsorption of one liquid component onto the wall can be controlled by chemical modification of the glass. The glass was treated with varying amounts of hexamethyldisilazane to decrease surface polarity and therefore enhance the adsorption of carbon disulfide in a surprisingly continuous way. The effect of the glass wall on the local liquid composition can be described by two different scaling hypotheses: using a short range field on the liquid closest to the wall, or pinning the amplitude of the order parameter at the surface. We have found that only the second approach is consistent with the experimental data, although this is difficult to reconcile with observed wetting critical phenomena. We also have reexamined the issue of substrate inhomogeneity and conclude that the substrates were indeed homogeneous on relevant length scales. Supported by the NSF under DMR-9320910 and the central facilities of the Materials Science Center at Cornell University.

  6. Hydrogen adsorption in metal-decorated silicon carbide nanotubes

    NASA Astrophysics Data System (ADS)

    Singh, Ram Sevak; Solanki, Ankit

    2016-09-01

    Hydrogen storage for fuel cell is an active area of research and appropriate materials with excellent hydrogen adsorption properties are highly demanded. Nanotubes, having high surface to volume ratio, are promising storage materials for hydrogen. Recently, silicon carbide nanotubes have been predicted as potential materials for future hydrogen storage application, and studies in this area are ongoing. Here, we report a systematic study on hydrogen adsorption properties in metal (Pt, Ni and Al) decorated silicon carbide nanotubes (SiCNTs) using first principles calculations based on density functional theory. The hydrogen adsorption properties are investigated by calculations of adsorption energy, electronic band structure, density of states (DOS) and Mulliken charge population analysis. Our findings show that hydrogen adsorptions on Pt, Ni and Al-decorated SiCNTs undergo spontaneous exothermic reactions with significant modulation of electronic structure of SiCNTs in all cases. Importantly, according to the Mulliken charge population analysis, dipole-dipole interaction causes chemisorptions of hydrogen in Pt, Ni and Al decorated SiCNTs with formation of chemical bonds. The study is a platform for the development of metal decorated SiCNTs for hydrogen adsorption or hydrogen storage application.

  7. Program Merges SAR Data on Terrain and Vegetation Heights

    NASA Technical Reports Server (NTRS)

    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.

  8. Mapping and monitoring renewable resources with space SAR

    NASA Technical Reports Server (NTRS)

    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.

  9. Process for combining multiple passes of interferometric SAR data

    DOEpatents

    Bickel, Douglas L.; Yocky, David A.; Hensley, Jr., William H.

    2000-11-21

    Interferometric synthetic aperture radar (IFSAR) is a promising technology for a wide variety of military and civilian elevation modeling requirements. IFSAR extends traditional two dimensional SAR processing to three dimensions by utilizing the phase difference between two SAR images taken from different elevation positions to determine an angle of arrival for each pixel in the scene. This angle, together with the two-dimensional location information in the traditional SAR image, can be transformed into geographic coordinates if the position and motion parameters of the antennas are known accurately.

  10. Use of SAR in Regional Methane Exchange Studies

    NASA Technical Reports Server (NTRS)

    Morrissey, L. A.; Livingston, G. P.; Durden, S. L.

    1994-01-01

    Significant sources of uncertainty in global trace gas budgets are due to lack of knowledge concerning the areal and temporal extent of source and sink areas. Synthetic aperture radar (SAR) is particularly suited to studies of northern ecosystems because of its all-weather operating capability which enables the acquisition of seasonal data. As key controls on methane exchange, the ability to differentiate major vegetation communities, inundation, and leaf area index (LAI) with satellite and airborne SAR data would increase the accuracy and precision of regional and seasonal estimates of methane exchange. The utility of SAR data for monitoring key controls on methane emissions from Arctic and boreal ecosystems is examined.

  11. Tunnel monitoring with an advanced InSAR technique

    NASA Astrophysics Data System (ADS)

    Rabus, Bernhard; Eppler, Jayson; Sharma, Jayanti; Busler, Jennifer

    2012-06-01

    The detection and monitoring of subsurface excavations has a variety of applications in both the civil and defense domains. We have developed a novel InSAR method (Homogenous Distributed Scatterer (HDS)-InSAR) that exploits both persistent point and coherent distributed scatterers by using adaptive multilooking of statistically homogenous pixel neighborhoods. In order to enhance the detection of small scale structures in low SNR environments a matched parametric spatio-temporal model is fit to the deformation signal. We illustrate the performance of our new method for the city of Vancouver over the last nine years using InSAR stacks of RADARSAT-1 and RADARSAT-2 data.

  12. The physics of vibrating scatterers in SAR imagery

    NASA Astrophysics Data System (ADS)

    André, D. B.; Blacknell, D.; Muff, D. G.; Nottingham, M. R.

    2011-06-01

    Measurement times for synthetic aperture radar (SAR) image collection can take from the order of seconds to minutes and consequently the technique is subject to imaging artefacts due to target motion. For example, imaged moving targets can be displaced and unfocussed and similarly for vibrating targets. Current understanding of this phenomenon is somewhat esoteric however this paper puts forward and demonstrates a visual explanation via the physics of modulated scatterer SAR images in the Fourier domain. This novel approach has led to an imagery analyst aid which associates a distinctive signature to modulated scatterer artefacts in SAR imagery and to an associated filter.

  13. Real-time SAR processing for search and rescue

    NASA Astrophysics Data System (ADS)

    Mansfield, Arthur W.; Rogers, George W.; Rais, Houra

    1998-09-01

    The most important parameter in Search and Rescue is the time it takes to locate the downed aircraft and rescue the survivors. The resulting requirement for wide-area coverage, fine resolution, and day-night all-weather operation dictates the use of a SAR sensor. The time urgency dictates a real-time or near real-time SAR processor. This paper presents alternative real-time architectures and gives the results of feasibility studies of the enabling technologies, including new work by the authors in the area of SAR data compression.

  14. Operational Quality Control of SAR Data under the IDEAS Contract

    NASA Astrophysics Data System (ADS)

    Griffiths, Emma; Haria, Kajal; Meadowws, Peter; Miranda, Nuno

    2010-12-01

    Operational Quality Control (QC) of ERS-1/2 Synthetic Aperture Radar (SAR), Envisat's Advanced Synthetic Aperture Radar (ASAR) and the Phased-Array L-band SAR (PALSAR) on board JAXA's Advanced Land Observing Satellite (ALOS) is currently carried out under the Image Data quality Evaluation and Analysis Service (IDEAS). This paper introduces the concept of IDEAS as it applies to SAR QC including the daily and long-term analysis and shows the interaces to related services, including ESA's user-facing Earth Observation (EO) Help Desk

  15. Applications of the EOS SAR to monitoring global change

    NASA Technical Reports Server (NTRS)

    Schier, Marguerite; Way, Jobea; Holt, Benjamin

    1991-01-01

    The SAR employed by NASA's Earth Observing System (EOS) is a multifrequency multipolarization radar which can conduct global monitoring of geophysical and biophysical parameters. The present discussion of the EOS SAR's role in global monitoring emphasizes geophysical product variables applicable to global hydrologic, biogeochemical, and energy cycle models. EOS SAR products encompass biomass, wetland areas, and phenologic and environmental states, in the field of ecosystem dynamics; soil moisture, snow moisture and extent, and glacier and ice sheet extent and velocity, in hydrologic cycle studies; surface-wave fields and sea ice properties, in ocean/atmosphere circulation; and the topography, erosion, and land forms of the solid earth.

  16. SAR Reduction of PIFA with EBG Structures for Mobile Applications

    NASA Astrophysics Data System (ADS)

    Kwak, Sangil; Sim, Dong-Uk; Kwon, Jong Hwa; Yun, Je Hoon

    This paper proposes two types of electromagnetic bandgap (EBG) structures aimed for SAR reduction on a mobile phone antenna. The EBG structures, one which uses vias while the other does not can reduce the surface wave and prevent the undesired radiation from the antenna. Thus, these structures can reduce the electromagnetic fields toward the human head direction and reduction the SAR value. Tests demonstrate the reduction of SAR values and therefore, the human body can be protected from hazard electromagnetic fields by using the proposed EBG structures, regardless of whether vias are used or not.

  17. Geologic process studies using Synthetic Aperture Radar (SAR) data

    NASA Technical Reports Server (NTRS)

    Evans, Diane L.

    1992-01-01

    The use of SAR data to study geologic processes for better understanding of recent tectonic activity and climate change as well as the mitigation of geologic hazards and exploration for nonrenewable resources is discussed. The geologic processes that are particularly amenable to SAR-based data include volcanism; soil erosion, degradation, and redistribution; coastal erosion and inundation; glacier fluctuations; permafrost; and crustal motions. When SAR data are combined with data from other planned spaceborne sensors including ESA ERS, the Japanese Earth Resources Satellite, and the Canadian Radarsat, it will be possible to build a time-series view of temporal changes over many regions of earth.

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

    NASA Technical Reports Server (NTRS)

    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.

  19. SAR image effects on coherence and coherence estimation.

    SciTech Connect

    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.

  20. Evaluation of ERIM optically processed SEASAT SAR data

    NASA Technical Reports Server (NTRS)

    Shuchman, R. A.; Lyzenga, D. R. (Principal Investigator); Klooster, A., Jr.; Marks, J.

    1982-01-01

    The results of three studies on the radiometric and geometric properties of optically processed SEASAT SAR imagery are summarized. The accuracy with which the image scale can be predicted based upon a knowledge of the SAR platform and recording system parameters and the processor characteristics was evaluated. The considerations involved in making radiometric measurements from image films, the use of point targets for calibrating the effects of Doppler spectrum shifts on the radiometric calibration of the SAR image data over extended swath lengths was evaluated

  1. A fundamental model and efficient inference for SAR ocean imagery

    NASA Technical Reports Server (NTRS)

    Harger, R. O.

    1984-01-01

    Employing a synthetic aperture radar (SAR) imaging model based on fundamental models of nonlinear hydrodynamics, electromagnetic scattering from a two-scale surface, and SAR imaging of a time-variant scene, the optimal (minimum mean-square error) estimates of the parameters of a sinusoidal, long gravity wave, and the short gravity wave ensemble are found in an efficient recursive form and their performance evaluated, generally by numerical simulation, in a one-dimensional stationary version. An application is made to Seasat-SAR complex imagery.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Jensen, Mark; Knight, Chad; Haslem, Brent

    2015-05-01

    The FlexSAR radar system was designed to be a high quality, low-cost, flexible prototype instrument. Many radar researchers and practitioners desire the ability to efficiently prototype novel configurations. However, the cost and time required to modify existing radar systems is a challenging hurdle that can be prohibitive. The FlexSAR system couples an RF design that leverages connectorized components with digital commercial-off-the-shelf (COTS) cards. This design allows for a scalable system that supports software defined radio (SDR) capabilities. This paper focuses on the RF and digital system design, discussing the advantages and disadvantages. The FlexSAR system design objective was to support diverse configurations with minimal non-recurring engineering (NRE) costs. Multiple diverse applications are examined, demonstrating the flexible system nature. The configurations discussed utilize different system parameters (e.g., number of phase-centers, transmit configurations, etc.). The resultant products are examined, illustrating that high-quality data products are still attained.

  4. Modification of porous starch for the adsorption of heavy metal ions from aqueous solution.

    PubMed

    Ma, Xiaofei; Liu, Xueyuan; Anderson, Debbie P; Chang, Peter R

    2015-08-15

    Porous starch xanthate (PSX) and porous starch citrate (PSC) were prepared in anticipation of the attached xanthate and carboxylate groups respectively forming chelation and electrostatic interactions with heavy metal ions in the subsequent adsorption process. The lead(II) ion was selected as the model metal and its adsorption by PSX and PSC was characterized. The adsorption capacity was highly dependent on the carbon disulfide/starch and citric acid/starch mole ratios used during preparation. The adsorption behaviors of lead(II) ion on PSXs and PSCs fit both the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum adsorption capacity from the Langmuir isotherm equation reached 109.1 and 57.6 mg/g for PSX and PSC when preparation conditions were optimized, and the adsorption times were just 20 and 60 min, respectively. PSX and PSC may be used as effective adsorbents for removal of heavy metals from contaminated liquid. PMID:25794731

  5. Modification of porous starch for the adsorption of heavy metal ions from aqueous solution.

    PubMed

    Ma, Xiaofei; Liu, Xueyuan; Anderson, Debbie P; Chang, Peter R

    2015-08-15

    Porous starch xanthate (PSX) and porous starch citrate (PSC) were prepared in anticipation of the attached xanthate and carboxylate groups respectively forming chelation and electrostatic interactions with heavy metal ions in the subsequent adsorption process. The lead(II) ion was selected as the model metal and its adsorption by PSX and PSC was characterized. The adsorption capacity was highly dependent on the carbon disulfide/starch and citric acid/starch mole ratios used during preparation. The adsorption behaviors of lead(II) ion on PSXs and PSCs fit both the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum adsorption capacity from the Langmuir isotherm equation reached 109.1 and 57.6 mg/g for PSX and PSC when preparation conditions were optimized, and the adsorption times were just 20 and 60 min, respectively. PSX and PSC may be used as effective adsorbents for removal of heavy metals from contaminated liquid.

  6. Carbon dioxide and nitrogen adsorption on cation-exchanged SSZ-13 zeolites.

    PubMed

    Pham, Trong D; Liu, Qingling; Lobo, Raul F

    2013-01-15

    Samples of high-silica SSZ-13, ion exchanged with protons and alkali-metal cations Li(+), Na(+), and K(+), were investigated using adsorption isotherms of CO(2) and N(2). The results show that Li-, Na-SSZ-13 have excellent CO(2) capacity at ambient temperature and pressure; in general, Li-SSZ-13 shows the highest capacity for N(2), CO(2) particularly in the low-pressure region. The effect of cation type and Si/Al ratio (6 and 12) on the adsorption properties was investigated through analysis of adsorption isotherms and heats of adsorption. The separation of CO(2) in a flue gas mixture was evaluated for these adsorbents in the pressure swing adsorption and vacuum pressure adsorption processes. PMID:23249267

  7. [Study on adsorption of tea polyphenol and caffine with polyamide resin].

    PubMed

    Tang, Ke-wen; Zhou, Chun-shan; Zhong, Shi-an; Zhu, Jie-ding

    2003-02-01

    The performance of adsorption of tea polyphenol and caffine with polyamide resin was investigated. The results obtained by spectrophotometry and HPLC show that the ability of adsorption of tea polyphenol with polyamide is stronger than that of caffine, in which hydrogen bond plays a very important role. The adsorption amount of caffine is 2.65 mg.g-1 with 7.5% adsorption ratio when 100 mL of 0.71 g.L-1 caffine is adsorbed on polyamide resine, but the adsorption amount of tea polyphenol is up to 148.13 mg.g-1 with 85% adsorption ratio when 700 mL of 1.98 g.L-1 tea polyphenol is adsorbed on polyamide resine. The dilution ratios of caffine and tea polyphenol are 74% and 90%, respectively, when they are diluted by 85% alcohol. The static adsorptions of caffine and tea polyphenol on polyamide resine reach equilibrium quickly in 80 min, and the plots of adsorption kinetics are nearly linear. Tea polyphenol and caffine are successfully separated on polyamide resine, and the obtained product contains more than 96% of tea polyphenol and 80% of EGCC with caffine less than 2.8%. PMID:12939992

  8. What have we learnt from SARS?

    PubMed Central

    Weiss, Robin A; McLean, Angela R

    2004-01-01

    With outbreaks of infectious disease emerging from animal sources, we have learnt to expect the unexpected. We were, and are, expecting a new influenza A pandemic, but no one predicted the emergence of an unknown coronavirus (CoV) as a deadly human pathogen. Thanks to the preparedness of the international network of influenza researchers and laboratories, the cause of severe acute respiratory syndrome (SARS) was rapidly identified, but there is no complacency over the global or local management of the epidemic in terms of public health logistics. The human population was lucky that only a small proportion of infected persons proved to be highly infectious to others, and that they did not become so before they felt ill. These were the features that helped to make the outbreak containable. The next outbreak of another kind of transmissible disease may well be quite different. PMID:15306402

  9. Multiscale MAP filtering of SAR images.

    PubMed

    Foucher, S; Bénié, G B; Boucher, J M

    2001-01-01

    Synthetic aperture radar (SAR) images are disturbed by a multiplicative noise depending on the signal (the ground reflectivity) due to the radar wave coherence. Images have a strong variability from one pixel to another reducing essentially the efficiency of the algorithms of detection and classification. We propose to filter this noise with a multiresolution analysis of the image. The wavelet coefficient of the reflectivity is estimated with a Bayesian model, maximizing the a posteriori probability density function. The different probability density function are modeled with the Pearson system of distributions. The resulting filter combines the classical adaptive approach with wavelet decomposition where the local variance of high-frequency images is used in order to segment and filter wavelet coefficients.

  10. A comparison of interferometric SAR antenna options

    NASA Astrophysics Data System (ADS)

    Doerry, A. W.; Bickel, D. L.

    2013-05-01

    Interferometric Synthetic Aperture Radar (IFSAR or InSAR) uses multiple antenna phase centers to ultimately measure target scene elevation. Its ability to do so depends on the antenna configuration, and how the multiple phase centers are employed. We examine several different dual-phase-center antenna configurations and modalities, including a conventional arrangement where a dedicated antenna is used to transmit and receive with another to receive only, a configuration where transmit and receive operations are ping-ponged between phase centers, a monopulse configuration, and an orthogonal waveform configuration. Our figure of merit is the RMS height noise in the elevation estimation. We show that a monopulse configuration is equivalent to the ping-pong scheme, and both offer an advantage over the conventional arrangement. The orthogonal waveform offers the best potential performance, if sufficient isolation can be achieved.

  11. SAR polar format implementation with MATLAB.

    SciTech Connect

    Martin, Grant D.; Doerry, Armin Walter

    2005-11-01

    Traditional polar format image formation for Synthetic Aperture Radar (SAR) requires a large amount of processing power and memory in order to accomplish in real-time. These requirements can thus eliminate the possible usage of interpreted language environments such as MATLAB. However, with trapezoidal aperture phase history collection and changes to the traditional polar format algorithm, certain optimizations make MATLAB a possible tool for image formation. Thus, this document's purpose is two-fold. The first outlines a change to the existing Polar Format MATLAB implementation utilizing the Chirp Z-Transform that improves performance and memory usage achieving near realtime results for smaller apertures. The second is the addition of two new possible image formation options that perform a more traditional interpolation style image formation. These options allow the continued exploration of possible interpolation methods for image formation and some preliminary results comparing image quality are given.

  12. A snow wetness retrieval algorithm for SAR

    NASA Technical Reports Server (NTRS)

    Shi, Jian-Cheng; Dozier, Jeff

    1992-01-01

    The objectives of this study are: (1) to evaluate the backscattering signals response to snow wetness; and (2) to develop an algorithm for snow wetness measurement using C-band polarimetric synthetic aperture radar (SAR). In hydrological investigations, modeling and forecasting of snowmelt runoff requires information about snowpack properties and their spatial variability. In particular, timely measurement of snow parameters is needed for operational hydrology. The liquid water content of snowpack is one of the important parameters. Active microwave sensors are highly sensitive to liquid water in the snowpack because of the large dielectric contrast between ice and water in the microwave spectrum. They are not affected by weather and have a spatial resolution compatible with the topographic variation in alpine regions. However, a quantitative algorithm for retrieval snow wetness has not yet been developed.

  13. Difference in receptor usage between severe acute respiratory syndrome (SARS) coronavirus and SARS-like coronavirus of bat origin.

    PubMed

    Ren, Wuze; Qu, Xiuxia; Li, Wendong; Han, Zhenggang; Yu, Meng; Zhou, Peng; Zhang, Shu-Yi; Wang, Lin-Fa; Deng, Hongkui; Shi, Zhengli

    2008-02-01

    Severe acute respiratory syndrome (SARS) is caused by the SARS-associated coronavirus (SARS-CoV), which uses angiotensin-converting enzyme 2 (ACE2) as its receptor for cell entry. A group of SARS-like CoVs (SL-CoVs) has been identified in horseshoe bats. SL-CoVs and SARS-CoVs share identical genome organizations and high sequence identities, with the main exception of the N terminus of the spike protein (S), known to be responsible for receptor binding in CoVs. In this study, we investigated the receptor usage of the SL-CoV S by combining a human immunodeficiency virus-based pseudovirus system with cell lines expressing the ACE2 molecules of human, civet, or horseshoe bat. In addition to full-length S of SL-CoV and SARS-CoV, a series of S chimeras was constructed by inserting different sequences of the SARS-CoV S into the SL-CoV S backbone. Several important observations were made from this study. First, the SL-CoV S was unable to use any of the three ACE2 molecules as its receptor. Second, the SARS-CoV S failed to enter cells expressing the bat ACE2. Third, the chimeric S covering the previously defined receptor-binding domain gained its ability to enter cells via human ACE2, albeit with different efficiencies for different constructs. Fourth, a minimal insert region (amino acids 310 to 518) was found to be sufficient to convert the SL-CoV S from non-ACE2 binding to human ACE2 binding, indicating that the SL-CoV S is largely compatible with SARS-CoV S protein both in structure and in function. The significance of these findings in relation to virus origin, virus recombination, and host switching is discussed.

  14. Global versus local adsorption selectivity

    NASA Astrophysics Data System (ADS)

    Pauzat, Françoise; Marloie, Gael; Markovits, Alexis; Ellinger, Yves

    2015-10-01

    The origin of the enantiomeric excess found in the amino acids present in the organic matter of carbonaceous meteorites is still unclear. Selective adsorption of one of the two enantiomers existing after a racemic formation could be part of the answer. Hereafter we report a comparative study of the adsorption of the R and S enantiomers of α-alanine and lactic acid on the hydroxylated { } chiral surface of α-quartz using numerical simulation techniques. Structurally different adsorption sites were found with opposite R versus S selectivity for the same molecule-surface couple, raising the problem of whether to consider adsorption as a local property or as a global response characteristic of the whole surface. To deal with the second term of this alternative, a statistical approach was designed, based on the occurrence of each adsorption site whose energy was calculated using first principle periodic density functional theory. It was found that R-alanine and S-lactic acid are the enantiomers preferentially adsorbed, even if the adsorption process on the quartz { } surface stays with a disappointingly poor enantio-selectivity. Nevertheless, it highlighted the important point that considering adsorption as a global property changes perspectives in the search for more efficient enantio-selective supports and more generally changes the way to apprehend adsorption processes in astro-chemistry/biology.

  15. Design method for adsorption beds

    NASA Technical Reports Server (NTRS)

    Blakely, R. L.; Jackson, J. K.

    1970-01-01

    Regenerable adsorption beds for long-term life support systems include synthetic geolite to remove carbon dioxide and silica gel to dehumidify the atmospheric gas prior to its passage through the geolite beds. Bed performance is evaluated from adsorption characteristics, heat and mass transfer, and pressure drop.

  16. Liquid-Phase Adsorption Fundamentals.

    ERIC Educational Resources Information Center

    Cooney, David O.

    1987-01-01

    Describes an experiment developed and used in the unit operations laboratory course at the University of Wyoming. Involves the liquid-phase adsorption of an organic compound from aqueous solution on activated carbon, and is relevant to adsorption processes in general. (TW)

  17. Sea bottom topography imaging with SAR

    NASA Technical Reports Server (NTRS)

    Vanderkooij, M. W. A.; Wensink, G. J.; Vogelzang, J.

    1992-01-01

    It is well known that under favorable meteorological and hydrodynamical conditions the bottom topography of shallow seas can be mapped with airborne or spaceborne imaging radar. This phenomenon was observed for the first time in 1969 by de Loor and co-workers in Q-band Side Looking Airborne Radar (SLAR) imagery of sandwaves in the North Sea. It is now generally accepted that the imaging mechanism consists of three steps: (1) interaction between (tidal) current and bottom topography causes spatial modulations in the surface current velocity; (2) modulations in the surface current velocity give rise to variations in the spectrum of wind-generated waves, as described by the action balance equation; and (3) variations in the wave spectrum show up as intensity modulations in radar imagery. In order to predict radar backscatter modulations caused by sandwaves, an imaging model, covering the three steps, was developed by the Dutch Sea Bottom Topography Group. This model and some model results will be shown. On 16 Aug. 1989 an experiment was performed with the polarimetric P-, L-, and C-band synthetic aperture radar (SAR) of NASA/JPL. One scene was recorded in SAR mode. On 12 Jul. 1991 another three scenes were recorded, of which one was in the ATI-mode (Along-Track Interferometer). These experiments took place in the test area of the Sea Bottom Topography Group, 30 km off the Dutch coast, where the bottom topography is dominated by sand waves. In-situ data were gathered by a ship in the test area and on 'Measuring Platform Noordwijk', 20 km from the center of the test area. The radar images made during the experiment were compared with digitized maps of the bottom. Furthermore, the profiles of radar backscatter modulation were compared with the results of the model. During the workshop some preliminary results of the ATI measurements will be shown.

  18. CARABAS - an airborne VHF SAR system

    SciTech Connect

    Larsson, B.; Frolined, P.O.; Gustavsson, A.

    1996-11-01

    There is an increasing interest in imaging radar systems operating at low frequencies, Examples of civilian and military applications are detection of stealth-designed man-made objects, targets hidden under foliage, biomass estimation, and penetration into glaciers or ground. CARABAS (Coherent All Radio Band Sensing) is a new airborne SAR system developed by FOA. It is designed for operation in the lowest part of the VHF band (20-90 NHz), using horizontal polarisation. This frequency region gives the system a good ability to penetrate vegetation and to some extent ground. CARABAS is the first known SAR sensor with a capability of diffraction limited imaging, i.e. a resolution in magnitude of the adopted wavelengths. A Sabreliner business jet aircraft is used as the airborne platform. Critical parts in the development have been the antenna system, the receiver and the processing algorithms. Based upon the experiences gained with CARABAS I a major system upgrade is now taking place. The new CARABAS II system is scheduled to fly in May 1996. This system is designed to give operational performance while CARABAS I was used to verify the feasibility. The first major field campaigns are planned for the second half of 1996. CARABAS II is jointly developed by FOA and Ericsson Microwave Systems AB in Sweden. This paper will give an overview of the system design and data collected with the current radar system, including some results for forested regions. The achieved system performance will be discussed, with a presentation of the major modifications made in the new CARABAS 11 system. 12 refs., 7 figs., 2 tabs.

  19. Soviet oceanographic synthetic aperture radar (SAR) research

    SciTech Connect

    Held, D.N.; Gasparovic, R.F.; Mansfield, A.W.; Melville, W.K.; Mollo-Christensen, E.L.; Zebker, H.A.

    1991-01-01

    Radar non-acoustic anti-submarine warfare (NAASW) became the subject of considerable scientific investigation and controversy in the West subsequent to the discovery by the Seasat satellite in 1978 that manifestations of underwater topography, thought to be hidden from the radar, were visible in synthetic aperture radar (SAR) images of the ocean. In addition, the Seasat radar produced images of ship wakes where the observed angle between the wake arms was much smaller than expected from classical Kelvin wake theory. These observations cast doubt on the radar oceanography community's ability to adequately explain these phenomena, and by extension on the ability of existing hydrodynamic and radar scattering models to accurately predict the observability of submarine-induced signatures. If one is of the opinion that radar NAASW is indeed a potentially significant tool in detecting submerged operational submarines, then the Soviet capability, as evidenced throughout this report, will be somewhat daunting. It will be shown that the Soviets have extremely fine capabilities in both theoretical and experimental hydrodynamics, that Soviet researchers have been conducting at-sea radar remote sensing experiments on a scale comparable to those of the United States for several years longer than we have, and that they have both an airborne and spaceborne SAR capability. The only discipline that the Soviet Union appears to be lacking is in the area of digital radar signal processing. If one is of the opinion that radar NAASW can have at most a minimal impact on the detection of submerged submarines, then the Soviet effort is of little consequence and poses not threat. 280 refs., 31 figs., 12 tabs.

  20. Bats and emerging zoonoses: henipaviruses and SARS.

    PubMed

    Field, H E

    2009-08-01

    Nearly 75% of all emerging infectious diseases (EIDs) that impact or threaten human health are zoonotic. The majority have spilled from wildlife reservoirs, either directly to humans or via domestic animals. The emergence of many can be attributed to predisposing factors such as global travel, trade, agricultural expansion, deforestation/habitat fragmentation, and urbanization; such factors increase the interface and/or the rate of contact between human, domestic animal, and wildlife populations, thereby creating increased opportunities for spillover events to occur. Infectious disease emergence can be regarded as primarily an ecological process. The epidemiological investigation of EIDs associated with wildlife requires a trans-disciplinary approach that includes an understanding of the ecology of the wildlife species, and an understanding of human behaviours that increase risk of exposure. Investigations of the emergence of Nipah virus in Malaysia in 1999 and severe acute respiratory syndrome (SARS) in China in 2003 provide useful case studies. The emergence of Nipah virus was associated with the increased size and density of commercial pig farms and their encroachment into forested areas. The movement of pigs for sale and slaughter in turn led to the rapid spread of infection to southern peninsular Malaysia, where the high-density, largely urban pig populations facilitated transmission to humans. Identifying the factors associated with the emergence of SARS in southern China requires an understanding of the ecology of infection both in the natural reservoir and in secondary market reservoir species. A necessary extension of understanding the ecology of the reservoir is an understanding of the trade, and of the social and cultural context of wildlife consumption. Emerging infectious diseases originating from wildlife populations will continue to threaten public health. Mitigating and managing the risk requires an appreciation of the connectedness between human

  1. Two microstrip arrays for interferometric SAR applications

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1993-01-01

    Two types of C-band aircraft interferometric Synthetic Aperture Radar (SAR) are being developed at JPL to measure the ocean wave characteristics. Each type requires two identical antennas with each having a long rectangular aperture to radiate fan-shaped beam(s). One type of these radars requires each of its antennas to radiate a broadside beam that will measure the target's cross-track velocity. The other type, having each of its antennas to radiate two off-broadside pointed beams, will allow the measurement of both the cross-track and the along-track velocities of the target. Because flush mounting of the antenna on the aircraft fuselage is desirable, microstrip patch array is selected for these interferometric SAR antennas. To meet the radar system requirement, each array needs a total of 76 microstrip patches which are arranged in a 38 x 2 rectangular aperture with a physical size of 1.6m x 16.5cm. To minimize the insertion loss and physical real estate of this relatively long array, a combined series/parallel feed technique is used. Techniques to suppress cross-pol radiation and to effectively utilize the RF power are also implemented. Cross-pol level of lower than -30 dB from the co-pol peak and low insertion loss of 0.36 dB have been achieved for both types of arrays. For the type of radar that requires two off-braodside pointed beams, a simple phasing technique is used to achieve this dual-beam capability with adequate antenna gain (20 dBi) and sidelobe level (-14 dB). Both radar arrays have been flight tested on aircraft with excellent antenna performance demonstrated.

  2. Study of scattering characteristics of lunar equatorial region using Chandrayaan-1 Mini-SAR polarimetric data

    NASA Astrophysics Data System (ADS)

    Saran, Sriram; Das, Anup; Mohan, Shiv; Chakraborty, Manab

    2012-10-01

    The miniaturized synthetic aperture radar Mini-SAR onboard Indian Chandrayaan-1 mission was the first ever lunar orbiting SAR that acquired several data strips covering a wide variety of geological units over lunar equatorial and low latitude regions, some of which were not studied earlier at radar wavelengths. The Mini-SAR observations, complemented by high resolution optical imagery and higher incidence angle radar datasets, were effectively used to create a catalog of SAR backscatter properties of various lunar geological features. The radar backscatter along with the parameters circular polarization ratio (CPR), relative phase (δ) and m (the degree of polarization)-chi (the Poincare ellipticity) decomposition technique were used to study the scattering mechanisms, surface/sub-surface roughness and regional topography of some of the craters and their ejecta fields. The study revealed that the Taylor and Descartes craters in the lunar highlands region were characterized by high backscatter and low CPR values, while the Maunder and Kopff craters in the Mare Orientale basin were characterized by relatively low backscatter and elevated CPR values. The fresh crater Jackson and its ejecta blankets on the lunar far-side showed very high backscatter along with elevated CPR values due to the presence of abundant wavelength-scale scatterers. The radar dark Pyroclastic Orientale ring deposits showed both low backscatter and low CPR values, as reported by previous radar observations of pyroclastic deposits. The elevated CPR values corresponding to the interior and exterior of Santos Dumont crater could be attributed to rough crater walls and regional topography, respectively. Finally, attempt was made to bring out the differences in the origin of two similar-sized craters Taylor and Kopff, with the help of SAR polarimetric parameters. Differences in the CPR values of Mare and highland craters were attributed to the sensitivity of CPR to the ilmenite content and presence of

  3. Decreasing range resolution of a SAR image to permit correction of motion measurement errors beyond the SAR range resolution

    DOEpatents

    Doerry, Armin W.; Heard, Freddie E.; Cordaro, J. Thomas

    2010-07-20

    Motion measurement errors that extend beyond the range resolution of a synthetic aperture radar (SAR) can be corrected by effectively decreasing the range resolution of the SAR in order to permit measurement of the error. Range profiles can be compared across the slow-time dimension of the input data in order to estimate the error. Once the error has been determined, appropriate frequency and phase correction can be applied to the uncompressed input data, after which range and azimuth compression can be performed to produce a desired SAR image.

  4. A Comparative Study of the Adsorption of Water and Methanol in Zeolite BEA: A Molecular Simulation Study

    SciTech Connect

    Nguyen, Van T.; Nguyen, Phuong T.; Dang, Liem X.; Mei, Donghai; Wick, Collin D.; Do, Duong D.

    2014-09-15

    Grand Canonical Monte Carlo (GCMC) simulations were carried out to study the equilibrium adsorption concentration of methanol and water in all-silica zeolite BEA over the wide temperature and pressure ranges. For both water and methanol, their adsorptive capacity increases with increasing pressure and decreasing temperature. The onset of methanol adsorption occurs at much lower pressures than water adsorption at all temperatures. Our GCMC simulation results also indicate that the adsorption isotherms of methanol exhibit a gradual change with pressure while water adsorption shows a sharp first-order phase transition at low temperatures. To explore the effects of Si/Al ratio on adsorption, a series of GCMC simulations of water and methanol adsorption in zeolites HBEA with Si/Al=7, 15, 31, 63 were performed. As the Si/Al ratio decreases, the onsets of both water and methanol adsorption dramatically shift to lower pressures. The type V isotherm obtained for water adsorption in hydrophobic BEA progressively changes to type I isotherm with decreasing Si/Al ratio in hydrophilic HBEA. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.

  5. Adsorptive removal of methylene blue by CuO-acid modified sepiolite as effective adsorbent and its regeneration with high-temperature gas stream.

    PubMed

    Su, Chengyuan; Wang, Liang; Chen, Menglin; Huang, Zhi; Lin, Xiangfeng

    2016-01-01

    In this study, the dynamic adsorption of methylene blue dye onto CuO-acid modified sepiolite was investigated. Meanwhile, the equilibrium and kinetic data of the adsorption process were studied to understand the adsorption mechanism. Furthermore, a high-temperature gas stream was applied to regenerate the adsorbent. The results showed that the Langmuir isotherm model was applied to describe the adsorption process. The positive value of enthalpy change indicated that the adsorption process was endothermic in nature. In the dynamic adsorption process, the best adsorption performance was achieved when the ratio of column height to diameter was 2.56 and the treatment capacity was 6 BV/h. The optimal scenario for regeneration experiments was the regeneration temperature of 550-650 °C, the space velocity of 100 min(-1) and the regeneration time of 10 min. The effective adsorption of CuO-acid modified sepiolite was kept for 12 cycles of adsorption and regeneration. PMID:27533859

  6. Crystal structure of the SarR protein from Staphylococcus aureus

    PubMed Central

    Liu, Yingfang; Manna, Adhar; Li, Ronggui; Martin, Wesley E.; Murphy, Robert C.; Cheung, Ambrose L.; Zhang, Gongyi

    2001-01-01

    The expression of virulence determinants in Staphylococcus aureus is controlled by global regulatory loci (e.g., sarA and agr). The sar (Staphylococcus accessory regulator) locus is composed of three overlapping transcripts (sarA P1, P3, and P2, transcripts initiated from the P1, P3, and P2 promoters, respectively), all encoding the 124-aa SarA protein. The level of SarA, the major regulatory protein, is partially controlled by the differential activation of the sarA promoters. We previously partially purified a 13.6-kDa protein, designated SarR, that binds to the sarA promoter region to down-modulate sarA transcription from the P1 promoter and subsequently SarA expression. SarR shares sequence similarity to SarA, and another SarA homolog, SarS. Here we report the 2.3 Å-resolution x-ray crystal structure of the dimeric SarR-MBP (maltose binding protein) fusion protein. The structure reveals that the SarR protein not only has a classic helix–turn–helix module for DNA binding at the major grooves, but also has an additional loop region involved in DNA recognition at the minor grooves. This interaction mode could represent a new functional class of the “winged helix” family. The dimeric SarR structure could accommodate an unusually long stretch of ≈27 nucleotides with two or four bending points along the course, which could lead to the bending of DNA by 90° or more, similar to that seen in the catabolite activator protein (CAP)–DNA complex. The structure also demonstrates the molecular basis for the stable dimerization of the SarR monomers and possible motifs for interaction with other proteins. PMID:11381122

  7. Diverse deformation patterns of Aleutian volcanoes from InSAR

    USGS Publications Warehouse

    Lu, Zhiming; Dzurisin, D.; Wicks, C.; Power, J.

    2008-01-01

    Interferometric synthetic aperture radar (InSAR) is capable of measuring ground-surface deformation with centimeter-to-subcentimeter precision at a spatial resolution of tens of meters over an area of hundreds to thousands of square kilometers. With its global coverage and all-weather imaging capability, InSAR has become an increasingly important measurement technique for constraining magma dynamics of volcanoes over remote regions such as the Aleutian Islands. The spatial pattern of surface deformation data derived from InSAR images enables the construction of detailed mechanical models to enhance the study of magmatic processes. This paper summarizes the diverse deformation patterns of the Aleutian volcanoes observed with InSAR and demonstrates that deformation patterns and associated magma supply mechanisms in the Aleutians are diverse and vary between volcanoes. These findings provide a basis for improved models and better understanding of magmatic plumbing systems.

  8. [Simulation of polarization SAR imaging of ocean surface].

    PubMed

    Guo, Ding; Gu, Xing-Fa; Yu, Tao; Fernado, N; Li, Juan; Chen, Xing-Feng

    2011-10-01

    The polarization synthetic aperture radar (SAR) imaging simulation is of great significance to ocean surface scattering. According to the theory of wind-wave spectrum, rough ocean surface was modeled in the present paper using the two-scale-model. This treatment takes both the large scale and small scale surface into account. By using the velocity bunching (VB) theory, Bragg scattering model and the small perturbation model (SPM), the polarization SAR system can simulate the ocean surface with various parameters and ocean states. The effects of the parameters of ocean waves and the parameters of SAR system were analyzed. Finally, some useful conclusions were drawn, which are helpful for extracting the information of ocean surface. The method is an effective way in the ocean SAR design and the ocean surface research.

  9. THE PRACTICE OF STRUCTURE ACTIVITY RELATIONSHIPS (SAR) IN TOXICOLOGY

    EPA Science Inventory

    Both qualitative and quantitative modeling methods relating chemical structure to biological activity, called structure-activity relationship analyses or SAR, are applied to the prediction and characterization of chemical toxicity. This minireview will discuss some generic issue...

  10. Nonuniform FFTs (NUFFT) algorithms applied to SAR imaging

    NASA Astrophysics Data System (ADS)

    Subiza, Begona; Gimeno-Nieves, Encarna; Lopez-Sanchez, Juan M.; Fortuny-Guasch, Joaquim

    2004-01-01

    Some recently developed algorithms known as Non-Uniform FFT's (NUFFT), which enable the computation of efficient FFT's with unequally spaced data in the time or frequency domain, have been applied to SAR imaging in this study. The main objective has been to analyze the potential improvement of the computational efficiency and/or image accuracy of seismic migration SAR processing techniques, like the ω-k algorithm. Our approach consists in substituting both the Stolt interpolation and the final range inverse FFT by a single NUFFT. Numerical simulations illustrate the performance of the new method and the influence of the selection of NUFFT parameters in the precision and computation time of the SAR imaging algorithm. The new method is especially suited for near-field wide-band configurations, such as inverse SAR (ISAR) and ground-based systems, where a very precise imaging algorithm is required.

  11. [Simulation of polarization SAR imaging of ocean surface].

    PubMed

    Guo, Ding; Gu, Xing-Fa; Yu, Tao; Fernado, N; Li, Juan; Chen, Xing-Feng

    2011-10-01

    The polarization synthetic aperture radar (SAR) imaging simulation is of great significance to ocean surface scattering. According to the theory of wind-wave spectrum, rough ocean surface was modeled in the present paper using the two-scale-model. This treatment takes both the large scale and small scale surface into account. By using the velocity bunching (VB) theory, Bragg scattering model and the small perturbation model (SPM), the polarization SAR system can simulate the ocean surface with various parameters and ocean states. The effects of the parameters of ocean waves and the parameters of SAR system were analyzed. Finally, some useful conclusions were drawn, which are helpful for extracting the information of ocean surface. The method is an effective way in the ocean SAR design and the ocean surface research. PMID:22250525

  12. A Study of Linear Approximation Techniques for SAR Azimuth Processing

    NASA Technical Reports Server (NTRS)

    Martinson, L. W.; Perry, R. P.; Liu, B.

    1979-01-01

    The application of the step transform subarray processing techniques to synthetic aperture radar (SAR) was studied. The subarray technique permits the application of efficient digital transform computational techniques such as the fast Fourier transform to be applied while offering an effective tool for range migration compensation. Range migration compensation is applied at the subarray level, and with the subarray size based on worst case range migration conditions, a minimum control system is achieved. A baseline processor was designed for a four-look SAR system covering approximately 4096 by 4096 SAR sample field every 2.5 seconds. Implementation of the baseline system was projected using advanced low power technologies. A 20 swath is implemented with approximately 1000 circuits having a power dissipation of from 70 to 195 watts. The baseline batch step transform processor is compared to a continuous strip processor, and variations of the baseline are developed for a wide range of SAR parameters.

  13. a Rail Central Displacement Method about Gb-Sar

    NASA Astrophysics Data System (ADS)

    Peng, J.; Cai, J.; Yang, H.

    2016-06-01

    This paper presents a new method to correct rail errors of Ground Based Synthetic Aperture Radar (GB-SAR) in the discontinue mode. Generally, "light positioning" is performed to mark the GB-SAR position in the dis-continuous observation mode. Usually we assume there is no difference between the marked position and the real installation position. But in fact, it is hard to keep the GB-SAR positions of two campaigns the same, so repositioning errors can't be neglected. In order to solve this problem, we propose an algorithm to correct the rail error after analyzing the GB-SAR rail error geometry. Results of the simulation experiment and the real experiment of a landslide in Lvliang, Shanxi, China, show the proposed method achieves an mm-level precision, enabling the D-GBSAR mode to be used in engineering projects.

  14. Land-cover classification in SAR images using dictionary learning

    NASA Astrophysics Data System (ADS)

    Aktaş, Gizem; Bak, Çaǧdaş; Nar, Fatih; Şen, Nigar

    2015-10-01

    Land-cover classification in Synthetic Aperture Radar (SAR) images has significance in both civil and military remote sensing applications. Accurate classification is a challenging problem due to variety of natural and man-made objects, seasonal changes at acquisition time, and diversity of image reconstruction algorithms.. In this study, Feature Preserving Despeckling (FPD), which is an edge preserving total variation based speckle reduction method, is applied as a preprocessing step. To handle the mentioned challenges, a novel feature extraction schema combined with a super-pixel segmentation and dictionary learning based classification is proposed. Computational complexity is another issue to handle in processing of high dimensional SAR images. Computational complexity of the proposed method is linearly proportional to the size of the image since it does not require a sliding window that accesses the pixels multiple times. Accuracy of the proposed method is validated on the dataset composed of TerraSAR-X high resolutions spot mode SAR images.

  15. Modeling of SAR signatures of shallow water ocean topography

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  16. A beamforming algorithm for bistatic SAR image formation.

    SciTech Connect

    Yocky, David Alan; Wahl, Daniel Eugene; Jakowatz, Charles V., Jr.

    2010-03-01

    Beamforming is a methodology for collection-mode-independent SAR image formation. It is essentially equivalent to backprojection. The authors have in previous papers developed this idea and discussed the advantages and disadvantages of the approach to monostatic SAR image formation vis--vis the more standard and time-tested polar formatting algorithm (PFA). In this paper we show that beamforming for bistatic SAR imaging leads again to a very simple image formation algorithm that requires a minimal number of lines of code and that allows the image to be directly formed onto a three-dimensional surface model, thus automatically creating an orthorectified image. The same disadvantage of beamforming applied to monostatic SAR imaging applies to the bistatic case, however, in that the execution time for the beamforming algorithm is quite long compared to that of PFA. Fast versions of beamforming do exist to help alleviate this issue. Results of image reconstructions from phase history data are presented.

  17. 3. DETAIL, LIGHTNING ARRESTER ON SAR TRANSMISSION LINE. EEC print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. DETAIL, LIGHTNING ARRESTER ON SAR TRANSMISSION LINE. EEC print no. S-C-01-00478, no date. Photographer unknown. - Santa Ana River Hydroelectric System, Transmission Lines, Redlands, San Bernardino County, CA

  18. High temperature adsorption measurements

    SciTech Connect

    Bertani, R.; Parisi, L.; Perini, R.; Tarquini, B.

    1996-12-31

    Adsorption phenomena are a rich and rather new field of study in geothermal research, in particular at very high temperature. ENEL is interested in the exploitation of geothermal regions with super-heated steam, and it is important to understand the behavior of water-rock interaction. We have analyzed in the 170-200{degrees}C temperature range four samples of Monteverdi cuttings; the next experimental effort will be at 220{degrees}C and over in 1996. The first results of the 1995 runs are collected in this paper. We can highlight four main items: (1) At relative pressures over 0.6 the capillarity forces are very important. (2) There is no significant temperature effect. (3) Adsorbed water can be present, and it is able to multiply by a factor of 15 the estimated reserve of super-heated steam only. (4) Pores smaller than 15 {Angstrom} do not contribute to the adsorbed mass.

  19. High temperature adsorption measurements

    SciTech Connect

    Bertani, R.; Parisi, L.; Perini, R.; Tarquini, B.

    1996-01-24

    Adsorption phenomena are a rich and rather new field of study in geothermal research, in particular at very high temperature. ENEL is interested in the exploitation of geothermal regions with superheated steam, and it is important to understand the behavior of water-rock interaction. We have analyzed in the 170-200 °C temperature range four samples of Monteverdi cuttings; the next experimental effort will be at 220 °C and over in 1996. The first results of the 1995 runs are collected in this paper. We can highlight four main items: 1. At relative pressures over 0.6 the capillarity forces are very important. 2. There is no significant temperature effect. 3. Adsorbed water can be present, and it is able to multiply by a factor of 15 the estimated reserve of super-heated steam only. 4. Pores smaller than 15 Å do not contribute to the adsorbed mass.

  20. SAR terrain classifier and mapper of biophysical attributes

    NASA Technical Reports Server (NTRS)

    Ulaby, Fawwaz T.; Dobson, M. Craig; Pierce, Leland; Sarabandi, Kamal

    1993-01-01

    In preparation for the launch of SIR-C/X-SAR and design studies for future orbital SAR, a program has made considerable progress in the development of an SAR terrain classifier and algorithms for quantification of biophysical attributes. The goal of this program is to produce a generalized software package for terrain classification and estimation of biophysical attributes and to make this package available to the larger scientific community. The basic elements of the SAR (Synthetic Aperture Radar) terrain classifier are outlined. An SAR image is calibrated with respect to known system and processor gains and external targets (if available). A Level 1 classifier operates on the data to differentiate: urban features, surfaces and tall and short vegetation. Level 2 classifiers further subdivide these classes on the basis of structure. Finally, biophysical and geophysical inversions are applied to each class to estimate attributes of interest. The process used to develop the classifiers and inversions is shown. Radar scattering models developed from theory and from empirical data obtained by truck-mounted polarimeters and the JPL AirSAR are validated. The validated models are used in sensitivity studies to understand the roles of various scattering sources (i.e., surface trunk, branches, etc.) in determining net backscatter. Model simulations of sigma (sup o) as functions of the wave parameters (lambda, polarization and angle of incidence) and the geophysical and biophysical attributes are used to develop robust classifiers. The classifiers are validated using available AirSAR data sets. Specific estimators are developed for each class on the basis of the scattering models and empirical data sets. The candidate algorithms are tested with the AirSAR data sets. The attributes of interest include: total above ground biomass, woody biomass, soil moisture and soil roughness.

  1. One carbon metabolism in SAR11 pelagic marine bacteria.

    PubMed

    Sun, Jing; Steindler, Laura; Thrash, J Cameron; Halsey, Kimberly H; Smith, Daniel P; Carter, Amy E; Landry, Zachary C; Giovannoni, Stephen J

    2011-01-01

    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 (14)C-labeled compounds to (14)CO(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 (14)C-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. PMID:21886845

  2. SAR image formation with azimuth interpolation after azimuth transform

    DOEpatents

    Doerry; Armin W. , Martin; Grant D. , Holzrichter; Michael W.

    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.

  3. Taiga forest stands and SAR: Monitoring for subarctic global change

    SciTech Connect

    Way, J.; Kwok, R.; Viereck, L.; Slaughter, C.; Dobson, C.

    1992-03-01

    In preparation for the first European Earth Remote Sensing (ERS-1) mission, a series of multitemporal, multifrequency, multipolarization aircraft synthetic aperture radar (SAR) data sets were acquired over the Bonanza Creek Experimental Forest near Fairbanks, Alaska in March 1988. Significant change in radar backscatter was observed over the two-week experimental period due to changing environmental conditions. These preliminary results are presented to illustrate the opportunity afforded by the ERS-1 SAR to monitor temporal change in forest ecosystems.

  4. InSAR Monitoring of Landslides using RADARSAT and Alos

    NASA Astrophysics Data System (ADS)

    Singhroy, V.; Pierre-Jean, A.; Pavlic, G.

    2009-05-01

    We present the results of InSAR monitoring of several landslides using RADARDAT, and ALOS satellites. InSAR techniques are increasingly being used in slope stability assessment. Our research has shown that differential InSAR and coherent target monitoring techniques using field corner reflectors are useful to monitor landslide activity along strategic transportation and energy corridors. The Mackenzie Valley in northern Canada is experiencing one of the highest rates on mean annual air temperature for any region in Canada, thereby triggering melting in the permafrost, which results in active layer detachment slides. There are approximately 2000 landslides along the proposed Mackenzie Valley pipeline route. In addition, the Trans Canada Highway in the Canadian Rockies are affected by several rock avalanches and slow retrogressive slides. The ALOS PALSAR InSAR results show that we can observe deformation on both vegetated and exposed rock areas on the Little Smokey slide and the Frank Slide. RADARSAT-1 InSAR images indicate the different level of activity of the slopes (large and small) during different periods of the year. RADARSAT-2 is providing the high resolution rapid revisit capabilities needed to continuously monitor these active slopes along Canadian strategic energy and transportation corridors. The information produced by our InSAR activity maps on various landslides are used to realign the pipeline route in sensitive permafrost areas, and to install slope stability measures along the Trans-Canada and Provincial Highways. Using these different satellites we are able to develop guidelines for more reliable uses of these SAR missions Keywords: InSAR, landslides, RADARSAT, ALOS .

  5. Fusion of LADAR with SAR for precision strike

    SciTech Connect

    Cress, D.H.; Muguira, M.R.

    1995-03-01

    This paper presents a concept for fusing 3-dimensional image reconnaissance data with LADAR imagery for aim point refinement. The approach is applicable to fixed or quasi-fixed targets. Quasi-fixed targets are targets that are not expected to be moved between the time of reconnaissance and the time of target engagement. The 3-dimensional image data is presumed to come from standoff reconnaissance assets tens to hundreds of kilometers from the target area or acquisitions prior to hostilities. Examples are synthetic aperture radar (SAR) or stereoprocessed satellite imagery. SAR can be used to generate a 3-dimensional map of the surface through processing of data acquired with conventional SAR acquired using two closely spaced, parallel reconnaissance paths, either airborne or satellite based. Alternatively, a specialized airborne SAR having two receiving antennas may be used for data acquisition. The data sets used in this analysis are: (1) LADAR data acquired using a Hughes-Danbury system flown over a portion of Kirtland AFB during the period September 15--16, 1993; (2) two pass interferometric SAR data flown over a terrain-dominated area of Kirtland AFB; (3) 3-dimensional mapping of an urban-dominated area of the Sandia National Laboratories and adjacent cultural area extracted from aerial photography by Vexcel Corporation; (4) LADAR data acquired at Eglin AFB under Wright Laboratory`s Advanced Technology Ladar System (ATLAS) program using a 60 {mu}J, 75 KHz Co{sub 2} laser; and (5) two pass interferometric SAR data generated by Sandia`s STRIP DCS (Data Collection System) radar corresponding to the ATLAS LADAR data. The cultural data set was used in the urban area rather than SAR because high quality interferometric SAR data were not available for the urban-type area.

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

    NASA Technical Reports Server (NTRS)

    Held, D. N.; Werner, C.

    1985-01-01

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

  7. Archived 1976-1985 JPL Aircraft SAR Data

    NASA Technical Reports Server (NTRS)

    Thompson, Thomas W.; Blom, Ronald G.

    2016-01-01

    This report describes archived data from the Jet Propulsion Laboratory (JPL) aircraft radar expeditions in the mid-1970s through the mid-1980s collected by Ron Blom, JPL Radar Geologist. The dataset was collected during Ron's career at JPL from the 1970s through 2015. Synthetic Aperture Radar (SAR) data in the 1970s and 1980s were recorded optically on long strips of film. SAR imagery was produced via an optical, holographic technique that resulted in long strips of film imagery.

  8. SAR11 bacteria linked to ocean anoxia and nitrogen loss

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  9. Playback system designed for X-Band SAR

    NASA Astrophysics Data System (ADS)

    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.

  10. InSAR monitoring of high risk geohazard sites

    NASA Astrophysics Data System (ADS)

    Singhroy, Vern

    InSAR techniques are increasingly being used in slope stability assessment, seismic and volcanic hazards. Our research has shown that differential InSAR and coherent target monitoring techniques using field corner reflectors are useful to monitor landslide activity along strategic transportation and energy corridors in Canada and China. We have also used InSAR techniques to monitor seismic activity on Vancouver Island. Our investigation has shown that differential InSAR and CTM techniques provide a useful monitoring technique for landslide activity under different slope, moisture and lithological conditions. On vegetated slopes, corner reflectors are being used to continuously monitor large active slopes. The series of InSAR images indicate the different level of activity of the slopes (large and small) during different periods of the year. The information produced by our InSAR activity maps are used to realign the pipeline route in sensitive permafrost areas, and to install slope stability measures along the Trans-Canada Highway. Recent RADARSAT-2 with its high resolution (3m) multi-incidence fully polarimetric capabilities are providing the high resolution rapid revisit capabilities needed to continuously monitor these active slopes along Canadian strategic energy and transportation corridors, as well as seismically active regions.

  11. SAR11 bacteria linked to ocean anoxia and nitrogen loss.

    PubMed

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

    2016-08-11

    Bacteria of the SAR11 clade constitute up to one half of all microbial cells in the oxygen-rich surface ocean. SAR11 bacteria are also abundant in oxygen minimum zones (OMZs), where oxygen falls below detection and anaerobic microbes have vital roles in converting bioavailable nitrogen to N2 gas. Anaerobic metabolism has not yet been observed in SAR11, and it remains unknown how these bacteria contribute to OMZ biogeochemical cycling. Here, genomic analysis of single cells from the world's largest OMZ revealed previously uncharacterized SAR11 lineages with adaptations for life without oxygen, including genes for respiratory nitrate reductases (Nar). SAR11 nar genes were experimentally verified to encode proteins catalysing the nitrite-producing first step of denitrification and constituted ~40% of OMZ nar transcripts, with transcription peaking in the anoxic zone of maximum nitrate reduction activity. These results link SAR11 to pathways of ocean nitrogen loss, redefining the ecological niche of Earth's most abundant organismal group. PMID:27487207

  12. DInSAR fringes simulation of sandbox models

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  13. From Maxwell's Equations to Polarimetric SAR Images: A Simulation Approach

    PubMed Central

    Sant'Anna, Sidnei J. S.; da S. Lacava, J. C.; Fernandes, David

    2008-01-01

    A new electromagnetic approach for the simulation of polarimetric SAR images is proposed. It starts from Maxwell's equations, employs the spectral domain full-wave technique, the moment method, and the stationary phase method to compute the far electromagnetic fields scattered by multilayer structures. A multilayer structure is located at each selected position of a regular rectangular grid of coordinates, which defines the scene area under imaging. The grid is determined taking into account the elementary scatter size and SAR operational parameters, such as spatial resolution, pixel spacing, look angle and platform altitude. A two-dimensional separable “sinc” function to represent the SAR spread point function is also considered. Multifrequency sets of single-look polarimetric SAR images are generated, in L-, C- and X-bands and the images are evaluated using several measurements commonly employed in SAR data analysis. The evaluation shows that the proposed simulation process is working properly, since the obtained results are in accordance with those presented in the literature. Therefore, this new approach becomes suitable for carrying out theoretical and practical studies using polarimetric SAR images.

  14. ISRO's dual frequency airborne SAR pre-cursor to NISAR

    NASA Astrophysics Data System (ADS)

    Ramanujam, V. Manavala; Suneela, T. J. V. D.; Bhan, Rakesh

    2016-05-01

    The Indian Space Research Organisation (ISRO) and the National Aeronautics and Space Administration (NASA) have jointly embarked on NASA-ISRO Synthetic Aperture Radar (NISAR) operating in L-band and S-band, which will map Earth's surface every 12 days. As a pre-cursor to the NISAR mission, ISRO is planning an airborne SAR (L&S band) which will deliver NISAR analogue data products to the science community. ISRO will develop all the hardware with the aim of adhering to system design aspects of NISAR to the maximum extent possible. It is a fully polarimetric stripmap SAR and can be operated in single, dual, compact, quasi-quad and full polarimetry modes. It has wide incidence angle coverage from 24°-77° with swath coverage from 5.5km to 15 km. Apart from simultaneous imaging operations, this system can also operate in standalone L/S SAR modes. This system is planned to operate from an aircraft platform with nominal altitude of 8000meters. Antenna for this SAR will be rigidly mounted to the aircraft, whereas, motion compensation will be implemented in the software processor to generate data products. Data products for this airborne SAR will be generated in slant & ground range azimuth dimension and geocoded in HDF5/Geotiff formats. This airborne SAR will help to prepare the Indian scientific community for optimum utilization of NISAR data. In-order to collect useful science data, airborne campaigns are planned from end of 2016 onwards.

  15. Velocity estimation of slow moving targets in AT-InSAR systems

    NASA Astrophysics Data System (ADS)

    Budillon, A.; Pascazio, V.; Schirinzi, G.

    2007-10-01

    Along Track Interferometric Synthetic Aperture Radar (AT-InSAR) systems use more than one SAR antennas (typically two), mounted on the same platform and displaced along the platform moving direction, to detect slow ground moving targets. The phase of the ATI signal is related to the target motion parameters and may thus be used to estimate the radial velocity. In this paper we approach the velocity estimation problem using statistical techniques based on the statistical distribution of the measured interferometric phases. We analyze the radial velocity estimation with respect to ATI system parameters, such as velocity values, the signal to clutter ratio (SCR), the clutter to noise ratio (CNR), considering a deterministic target whose velocity is estimated using a Gaussian model. This model allows to take into account the lack of knowledge of the target radar cross section (RCS) values and provides an analytical form for the interferometric phase probability density function. Simulations results show that the adoption of Maximum Likelihood (ML) techniques, to perform a joint estimation of velocity and SCR, and multi-channel configurations, to overcome ambiguities problems, provide very good velocity estimation accuracy.

  16. Characteristics of Forests in Western Sayani Mountains, Siberia from SAR Data

    NASA Technical Reports Server (NTRS)

    Ranson, K. Jon; Sun, Guoqing; Kharuk, V. I.; Kovacs, Katalin

    1998-01-01

    This paper investigated the possibility of using spaceborne radar data to map forest types and logging in the mountainous Western Sayani area in Siberia. L and C band HH, HV, and VV polarized images from the Shuttle Imaging Radar-C instrument were used in the study. Techniques to reduce topographic effects in the radar images were investigated. These included radiometric correction using illumination angle inferred from a digital elevation model, and reducing apparent effects of topography through band ratios. Forest classification was performed after terrain correction utilizing typical supervised techniques and principal component analyses. An ancillary data set of local elevations was also used to improve the forest classification. Map accuracy for each technique was estimated for training sites based on Russian forestry maps, satellite imagery and field measurements. The results indicate that it is necessary to correct for topography when attempting to classify forests in mountainous terrain. Radiometric correction based on a DEM (Digital Elevation Model) improved classification results but required reducing the SAR (Synthetic Aperture Radar) resolution to match the DEM. Using ratios of SAR channels that include cross-polarization improved classification and

  17. Separation of capsaicin from capsaicinoids by macroporous resin adsorption chromatography.

    PubMed

    Liu, Changxia; Liu, Ruican; Zhang, Peng; Chen, Yiming; Xu, Tao; Wang, Fang; Tan, Tianwei; Liu, Chunqiao

    2015-12-01

    The aim of present study is to develop an efficient and low-cost method for capsaicin production isolated from capsaicinoids by macroporous resin adsorption chromatography. HZ816 resin has shown the best adsorption and desorption capacities for capsaicin among other resins. To optimize the operating parameters for separation, initial concentration, diameter-to-height ratio, mobile phase ratio, and crystallization method were investigated. When capsaicinoids solution (5 g/L) was loaded onto the column (diameter-to-height ratio = 1:12) with ethanol/1% w/w NaOH (4:6, v/v) as the mobile phase, capsaicin was purified most effectively. By using acid neutralization as the crystallization method, the purity of capsaicin improved from 90.3 to 99.5% with 82.3% yield. In conclusion, this study provides a simple and low-cost method for the industrial-scale production of high-purity capsaicin. PMID:26456215

  18. Quantitation of enantiospecific adsorption on chiral nanoparticles from optical rotation

    NASA Astrophysics Data System (ADS)

    Shukla, Nisha; Ondeck, Nathaniel; Gellman, Andrew J.

    2014-11-01

    Au nanoparticles modified with enantiomerically pure D- or L-cysteine have been shown to serve as enantioselective adsorbents of R- and S-propylene oxide. A simple adsorption model and accompanying experimental protocol have been developed to enable optical rotation measurements to be analyzed for quantitative determination of the ratios of the enantiospecific adsorption equilibrium constants of chiral species on the surfaces of chiral nanoparticles, KLS/KDS = KDR/KLR. This analysis is robust in the sense that it obviates the need to measure the absolute surface area of the absorbent nanoparticles, a quantity that is somewhat difficult to obtain accurately. This analysis has been applied to optical rotation data obtained from solutions of R- and S-propylene oxide, in varying concentration ratios, with D- and L-cysteine coated Au nanoparticles, in varying concentration ratios.

  19. Adsorption characteristics of Congo Red onto the chitosan/montmorillonite nanocomposite.

    PubMed

    Wang, Li; Wang, Aiqin

    2007-08-25

    A series of biopolymer chitosan/montmorillonite (CTS/MMT) nanocomposites were prepared by controlling the molar ratio of chitosan (CTS) and montmorillonite (MMT). The nanocomposites were characterized by FTIR and XRD. The effects of different molar ratios of CTS and MMT, initial pH value of the dye solution and temperature on adsorption capacities of samples for Congo Red (CR) dye have been investigated. The adsorption capacities of CTS, MMT and CTS/MMT nanocomposite with CTS to MMT molar ratio of 5:1 for CR were compared. The results indicated that the adsorption capacity of CTS/MMT nanocomposite was higher than the mean values of those of CTS and MMT. The adsorption kinetics and isotherms were also studied. It was shown that all the sorption processes were better fitted by pseudo-second-order equation and the Langmuir equation. PMID:17349744

  20. Psychosocial effects of SARS on hospital staff: survey of a large tertiary care institution

    PubMed Central

    Nickell, Leslie A.; Crighton, Eric J.; Tracy, C. Shawn; Al-Enazy, Hadi; Bolaji, Yemisi; Hanjrah, Sagina; Hussain, Ayesha; Makhlouf, Samia; Upshur, Ross E.G.

    2004-01-01

    Background The outbreak of SARS in 2003 had a dramatic effect on the health care system in Toronto. The main objective of this study was to investigate the psychosocial effects associated with working in a hospital environment during this outbreak. Methods Questionnaires were distributed to all willing employees of Sunnybrook and Women's College Health Sciences Centre between Apr. 10 and 22, 2003. The survey included questions regarding concern about SARS, precautionary measures, personal well-being and sociodemographic characteristics; a subsample also received the 12-item version of the General Health Questionnaire (GHQ-12). Results Of the 4283 questionnaires distributed, 2001 (47%) were returned, representing 27% of the total hospital employee population of 7474. The proportions of respondents who were allied health care professionals, nurses and doctors and who worked in areas other than patient care were representative of the hospital staff population as a whole. Of the 2001 questionnaires, 510 contained the GHQ-12. Two-thirds of the respondents reported SARS-related concern for their own or their family's health. A total of 148 respondents (29%) scored above the threshold point on the GHQ-12, indicating probable emotional distress; the rate among nurses was 45%. Masks were reported to be the most bothersome infection control precaution. Logistic regression analysis identified 4 factors as being significantly associated with increased levels of concern for personal or family health: perception of a greater risk of death from SARS (adjusted odds ratio [OR] 5.0, 95% confidence interval [CI] 2.6–9.6), living with children (adjusted OR 1.8, 95% CI 1.5–2.3), personal or family lifestyle affected by SARS outbreak (adjusted OR 3.3, 95% CI 2.5–4.3) and being treated differently by people because of working in a hospital (adjusted OR 1.6, 95% CI 1.2–2.1). Four factors were identified as being significantly associated with the presence of emotional distress

  1. Protein Adsorption in Three Dimensions

    PubMed Central

    Vogler, Erwin A.

    2011-01-01

    Recent experimental and theoretical work clarifying the physical chemistry of blood-protein adsorption from aqueous-buffer solution to various kinds of surfaces is reviewed and interpreted within the context of biomaterial applications, especially toward development of cardiovascular biomaterials. The importance of this subject in biomaterials surface science is emphasized by reducing the “protein-adsorption problem” to three core questions that require quantitative answer. An overview of the protein-adsorption literature identifies some of the sources of inconsistency among many investigators participating in more than five decades of focused research. A tutorial on the fundamental biophysical chemistry of protein adsorption sets the stage for a detailed discussion of the kinetics and thermodynamics of protein adsorption, including adsorption competition between two proteins for the same adsorbent immersed in a binary-protein mixture. Both kinetics and steady-state adsorption can be rationalized using a single interpretive paradigm asserting that protein molecules partition from solution into a three-dimensional (3D) interphase separating bulk solution from the physical-adsorbent surface. Adsorbed protein collects in one-or-more adsorbed layers, depending on protein size, solution concentration, and adsorbent surface energy (water wettability). The adsorption process begins with the hydration of an adsorbent surface brought into contact with an aqueous-protein solution. Surface hydration reactions instantaneously form a thin, pseudo-2D interface between the adsorbent and protein solution. Protein molecules rapidly diffuse into this newly-formed interface, creating a truly 3D interphase that inflates with arriving proteins and fills to capacity within milliseconds at mg/mL bulk-solution concentrations CB. This inflated interphase subsequently undergoes time-dependent (minutes-to-hours) decrease in volume VI by expulsion of either-or-both interphase water and

  2. InSAR Scientific Computing Environment

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  3. Mitigating illumination gradients in a SAR image based on the image data and antenna beam pattern

    DOEpatents

    Doerry, Armin W.

    2013-04-30

    Illumination gradients in a synthetic aperture radar (SAR) image of a target can be mitigated by determining a correction for pixel values associated with the SAR image. This correction is determined based on information indicative of a beam pattern used by a SAR antenna apparatus to illuminate the target, and also based on the pixel values associated with the SAR image. The correction is applied to the pixel values associated with the SAR image to produce corrected pixel values that define a corrected SAR image.

  4. Generalized energy-aperture product limit for multi-beam and spotlight SARs

    SciTech Connect

    Karr, T.J.

    1995-12-21

    The SAR energy-aperture product limit is extended to multi-beam SARS, Spotlight and moving spotlight SARS. This fundamental limit bounds the tradeoff between energy and antenna size. The kinematic relations between design variables such as platform speed, pulse repetition frequency, beam width and area rate are analyzed in a unified framework applicable to a wide variety of SARs including strip maps, spotlights, vermer arrays and multi-beam SARS, both scanning and swept-beam. Then the energy-aperture product limit is derived from the signal-to noise requirement and the kinematic constraints. The derivation clarifies impact of multiple beams and spotlighting on SAR performance.

  5. Centrifugal Adsorption Cartridge System

    NASA Technical Reports Server (NTRS)

    Gonda, Steve R.; Tsao, Yow-Min D.; Lee, Wenshan

    2004-01-01

    The centrifugal adsorption cartridge system (CACS) is an apparatus that recovers one or more bioproduct(s) from a dilute aqueous solution or suspension flowing from a bioreactor. The CACS can be used both on Earth in unit gravity and in space in low gravity. The CACS can be connected downstream from the bioreactor; alternatively, it can be connected into a flow loop that includes the bioreactor so that the liquid can be recycled. A centrifugal adsorption cartridge in the CACS (see figure) includes two concentric cylinders with a spiral ramp between them. The volume between the inner and outer cylinders, and between the turns of the spiral ramp is packed with an adsorbent material. The inner cylinder is a sieve tube covered with a gas-permeable, hydrophobic membrane. During operation, the liquid effluent from the bioreactor is introduced at one end of the spiral ramp, which then constrains the liquid to flow along the spiral path through the adsorbent material. The spiral ramp also makes the flow more nearly uniform than it would otherwise be, and it minimizes any channeling other than that of the spiral flow itself. The adsorbent material is formulated to selectively capture the bioproduct(s) of interest. The bioproduct(s) can then be stored in bound form in the cartridge or else eluted from the cartridge. The centrifugal effect of the spiral flow is utilized to remove gas bubbles from the liquid. The centrifugal effect forces the bubbles radially inward, toward and through the membrane of the inner cylinder. The gas-permeable, hydrophobic membrane allows the bubbles to enter the inner cylinder while keeping the liquid out. The bubbles that thus enter the cylinder are vented to the atmosphere. The spacing between the ramps determines rate of flow along the spiral, and thereby affects the air-bubble-removal efficiency. The spacing between the ramps also determines the length of the fluid path through the cartridge adsorbent, and thus affects the bioproduct

  6. Geodetic imaging of tectonic deformation with InSAR

    NASA Astrophysics Data System (ADS)

    Fattahi, Heresh

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

  7. [Thermodynamics adsorption and its influencing factors of chlorpyrifos and triazophos on the bentonite and humus].

    PubMed

    Zhu, Li-Jun; Zhang, Wei; Zhang, Jin-Chi; Zai, De-Xin; Zhao, Rong

    2010-11-01

    The adsorption of chlorpyrifos and triazophos on bentonite and humus was investigated by using the equilibrium oscillometry. The adsorption capacity of chlorpyrifos and triazophos on humus was great higher than bentonite at the same concentration. Equilibrium data of Langmuir, Freundlich isotherms showed significant relationship to the adsorption of chlorpyrifos and triazophos on humus (chlorpyrifos: R2 0.996 4, 0.996 3; triazophos: R2 0.998 9, 0.992 4). Langmuir isotherm was the best for chlorpyrifos and triazophos on bentonite (chlorpyrifos: R2 = 0.995 7, triazophos: R2 = 0.998 9). The pH value, adsorption equilibrium time and temperature were the main factors affecting adsorption of chlorpyrifos and triazophos on bentonite and humus. The adsorption equilibrium time on mixed adsorbent was 12h for chlorpyrifos and 6h for triazophos respectively. The mass ratio of humus and bentonite was 12% and 14% respectively, the adsorption of chlorpyrifos and triazophos was the stronglest and tended to saturation. At different temperatures by calculating the thermodynamic parameters deltaG, deltaH and deltaS, confirmed that the adsorption reaction was a spontaneous exothermic process theoretically. The adsorption was the best when the pH value was 6.0 and the temperature was 15 degrees C.

  8. Adsorption of cadmium ions on oxygen surface sites in activated carbon

    SciTech Connect

    Jia, Y.F.; Thomas, K.M.

    2000-02-08

    Various types of oxygen functional groups were introduced onto the surface of coconut shell derived activated carbon by oxidation using nitric acid. Fourier-transform infrared spectroscopy (FTIR), temperature-programmed desorption (TPD), and selective neutralization were used to characterize the surface oxygen functional groups. The oxidized carbons were also heat treated to provide a suite of carbons where the oxygen functional groups of various thermal stabilities were varied progressively. The adsorption of cadmium ions was enhanced dramatically by oxidation of the carbon. The ratio of released protons to adsorbed cadmium ions on oxidized carbon was approximately 2, indicating cation exchange was involved in the process of adsorption. Na{sup +} exchange studies with the oxidized carbon gave a similar ratio. After heat treatment of the oxidized carbons to remove oxygen functional groups, the ratio of H{sup +} released to Cd{sup 2+} adsorbed and the adsorption capacity decreased significantly. Both reversible and irreversible processes were involved in cadmium ion adsorption with reversible adsorption having higher enthalpy. The irreversible adsorption resulted from cation exchange with carboxylic acid groups, whereas the reversible adsorption probably involved physisorption of the partially hydrated cadmium ion.

  9. Measuring Thermokarst Subsidence Using InSAR: Potential and Pitfalls

    NASA Astrophysics Data System (ADS)

    Liu, L.; Schaefer, K. M.; Chen, A. C.; Gusmeroli, A.; Zebker, H. A.; Zhang, T.

    2014-12-01

    Thawing of ice-rich permafrost results in irregular, depressed landforms known as thermokarst terrain. The significant subsidence leading to thermokarst features can expand lakes, drain lakes, accelerate thaw, disturb the soil column, and promote erosion. Consequently, it affects many permafrost-region processes including vegetation succession, hydrology, and carbon storage and cycling. Many remote sensing studies identify thermokarst landforms and catalog their ever-changing areas. Yet the intrinsic dynamic thermokarst process, namely surface subsidence, remains a challenge to map and is seldom examined using remote sensing methods. Interferometric Synthetic Aperture Radar (InSAR) is a remote sensing technique that uses a time-series of satellite SAR images to measure cm-level land surface deformation. We demonstrate the capabilities and limitations of space-borne InSAR data to map thermokarst subsidence at a site located near Prudhoe Bay, on the North Slope of Alaska. A pipeline access road was constructed at this site in the 1970s, and is likely to have triggered the thawing of the region's permafrost, causing subsequent expansion of thermokarst-landform terrain. Our InSAR analysis using ALOS PALSAR images reveals that the thermokarst landforms in this region have undergone up to 10 cm of surface subsidence each summer from 2007 to 2010. This pilot study demonstrates the application of InSAR to map localized mass movement in permafrost terrain. We also illustrate how the effectiveness and accuracy of InSAR measurements are limited by several factors such as loss of interferometric coherence due to fast changes of ground surface conditions, spatial and temporal resolutions of InSAR data, and difficulty separating long-term and seasonal deformation signals.

  10. A double epidemic model for the SARS propagation

    PubMed Central

    Ng, Tuen Wai; Turinici, Gabriel; Danchin, Antoine

    2003-01-01

    Background An epidemic of a Severe Acute Respiratory Syndrome (SARS) caused by a new coronavirus has spread from the Guangdong province to the rest of China and to the world, with a puzzling contagion behavior. It is important both for predicting the future of the present outbreak and for implementing effective prophylactic measures, to identify the causes of this behavior. Results In this report, we show first that the standard Susceptible-Infected-Removed (SIR) model cannot account for the patterns observed in various regions where the disease spread. We develop a model involving two superimposed epidemics to study the recent spread of the SARS in Hong Kong and in the region. We explore the situation where these epidemics may be caused either by a virus and one or several mutants that changed its tropism, or by two unrelated viruses. This has important consequences for the future: the innocuous epidemic might still be there and generate, from time to time, variants that would have properties similar to those of SARS. Conclusion We find that, in order to reconcile the existing data and the spread of the disease, it is convenient to suggest that a first milder outbreak protected against the SARS. Regions that had not seen the first epidemic, or that were affected simultaneously with the SARS suffered much more, with a very high percentage of persons affected. We also find regions where the data appear to be inconsistent, suggesting that they are incomplete or do not reflect an appropriate identification of SARS patients. Finally, we could, within the framework of the model, fix limits to the future development of the epidemic, allowing us to identify landmarks that may be useful to set up a monitoring system to follow the evolution of the epidemic. The model also suggests that there might exist a SARS precursor in a large reservoir, prompting for implementation of precautionary measures when the weather cools down. PMID:12964944

  11. Applying target shadow models for SAR ATR

    NASA Astrophysics Data System (ADS)

    Papson, Scott; Narayanan, Ram M.

    2007-04-01

    Recent work has suggested that target shadows in synthetic aperture radar (SAR) images can be used effectively to aid in target classification. The method outlined in this paper has four steps - segmentation, representation, modeling, and selection. Segmentation is the process by which a smooth, background-free representation of the target's shadow is extracted from an image chip. A chain code technique is then used to represent the shadow boundary. Hidden Markov modeling is applied to sets of chain codes for multiple targets to create a suitable bank of target representations. Finally, an ensemble framework is proposed for classification. The proposed model selection process searches for an optimal ensemble of models based on various target model configurations. A five target subset of the MSTAR database is used for testing. Since the shadow is a back-projection of the target profile, some aspect angles will contain more discriminatory information then others. Therefore, performance is investigated as a function of aspect angle. Additionally, the case of multiple target looks is considered. The capability of the shadow-only classifier to enhance more traditional classification techniques is examined.

  12. Bandwidth requirements for fine resolution squinted SAR

    SciTech Connect

    DOERRY,ARMIN W.

    2000-03-01

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

  13. Anisotropic model-based SAR processing

    NASA Astrophysics Data System (ADS)

    Knight, Chad; Gunther, Jake; Moon, Todd

    2013-05-01

    Synthetic aperture radar (SAR) collections that integrate over a wide range of aspect angles hold the potentional for improved resolution and fosters improved scene interpretability and target detection. However, in practice it is difficult to realize the potential due to the anisotropic scattering of objects in the scene. The radar cross section (RCS) of most objects changes as a function of aspect angle. The isotropic assumption is tacitly made for most common image formation algorithms (IFA). For wide aspect scenarios one way to account for anistropy would be to employ a piecewise linear model. This paper focuses on such a model but it incorporates aspect and spatial magnitude filters in the image formation process. This is advantageous when prior knowledge is available regarding the desired targets' RCS signature spatially and in aspect. The appropriate filters can be incorporated into the image formation processing so that specific targets are emphasized while other targets are suppressed. This is demonstrated on the Air Force Research Laboratory (AFRL) GOTCHA1 data set to demonstrate the utility of the proposed approach.

  14. Short-Cycle Adsorption Refrigerator

    NASA Technical Reports Server (NTRS)

    Chan, C. K.

    1988-01-01

    Modular adsorption/Joule-Thomson-effect refrigerator offers fast regeneration; adsorption/desorption cycle time expected to be 1 minute. Pressurized hydrogen generated by bank of compressor modules during heating phase passes through system of check valves and expands in Joule-Thomson junction as it enters refrigeration chamber. Hydrogen absorbs heat from load before it is sucked out by another bank of compressor modules in cooling phase.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. Robust design of binary countercurrent adsorption separation processes

    SciTech Connect

    Storti, G. ); Mazzotti, M.; Morbidelli, M.; Carra, S. )

    1993-03-01

    The separation of a binary mixture, using a third component having intermediate adsorptivity as desorbent, in a four section countercurrent adsorption separation unit is considered. A procedure for the optimal and robust design of the unit is developed in the frame of Equilibrium Theory, using a model where the adsorption equilibria are described through the constant selectivity stoichiometric model, while mass-transfer resistances and axial mixing are neglected. By requiring that the unit achieves complete separation, it is possible to identify a set of implicity constraints on the operating parameters, that is, the flow rate ratios in the four sections of the unit. From these constraints explicit bounds on the operating parameters are obtained, thus yielding a region in the operating parameters space, which can be drawn a priori in terms of the adsorption equilibrium constants and the feed composition. This result provides a very convenient tool to determine both optimal and robust operating conditions. The latter issue is addressed by first analyzing the various possible sources of disturbances, as well as their effect on the separation performance. Next, the criteria for the robust design of the unit are discussed. Finally, these theoretical findings are compared with a set of experimental results obtained in a six port simulated moving bed adsorption separation unit operated in the vapor phase.

  17. Surfactant adsorption kinetics in microfluidics

    PubMed Central

    Riechers, Birte; Maes, Florine; Akoury, Elias; Semin, Benoît; Gruner, Philipp; Baret, Jean-Christophe

    2016-01-01

    Emulsions are metastable dispersions. Their lifetimes are directly related to the dynamics of surfactants. We design a microfluidic method to measure the kinetics of adsorption of surfactants to the droplet interface, a key process involved in foaming, emulsification, and droplet coarsening. The method is based on the pH decay in the droplet as a direct measurement of the adsorption of a carboxylic acid surfactant to the interface. From the kinetic measurement of the bulk equilibration of the pH, we fully determine the adsorption process of the surfactant. The small droplet size and the convection during the droplet flow ensure that the transport of surfactant through the bulk is not limiting the kinetics of adsorption. To validate our measurements, we show that the adsorption process determines the timescale required to stabilize droplets against coalescence, and we show that the interface should be covered at more than 90% to prevent coalescence. We therefore quantitatively link the process of adsorption/desorption, the stabilization of emulsions, and the kinetics of solute partitioning—here through ion exchange—unraveling the timescales governing these processes. Our method can be further generalized to other surfactants, including nonionic surfactants, by making use of fluorophore–surfactant interactions. PMID:27688765

  18. PDMS compound adsorption in context.

    PubMed

    Li, Nianzhen; Schwartz, Michael; Ionescu-Zanetti, Cristian

    2009-02-01

    Soft lithography of polydimethylsiloxane (PDMS), an elastomeric polymer, has enabled rapid and inexpensive fabrication of microfluidic devices for various biotechnology applications. However, concerns remain about adsorption of compounds on PDMS surfaces because of its porosity and hydrophobicity. Here, the adsorption of 2 small fluorescent dyes of different hydrophobicity (calcein and 5- (and 6-)carboxytetramethylrhodamine (TMR)) on PDMS surface has been systematically characterized, and PDMS adsorption has been compared with 2 traditional substrates: glass and polystyrene. To characterize adsorption in a regimen that is more relevant to microfluidic applications, the adsorption and desorption of the 2 compounds in PDMS microfluidic channels under flow conditions were also studied. Results showed that there was minimal adsorption of the hydrophilic compound calcein on PDMS, whereas the more hydrophobic TMR adsorbed on PDMS up to 4 times of that on glass or polystyrene. Under flow conditions, the desorption profiles and times needed to drop desorbed compound concentrations to negligible levels (desorption time constant, 10-42 s) were characterized. In the worst case scenario, after a 4-min exposure to TMR, 4 min of continuous wash resulted in compound concentrations in the microchannels to drop to values below 2 x 10(- 5) of the initial concentration.

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

    PubMed

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

    2016-04-12

    Severe acute respiratory syndrome (SARS) is a highly contagious infectious disease which first emerged in late 2002, caused by a then novel human coronavirus, SARS coronavirus (SARS-CoV). The virus is believed to have originated from bats and transmitted to human through intermediate animals such as civet cats. The re-emergence of SARS-CoV remains a valid concern due to the continual persistence of zoonotic SARS-CoVs and SARS-like CoVs (SL-CoVs) in bat reservoirs. In this study, the screening for the presence of SARS-specific T cells in a cohort of three SARS-recovered individuals at 9 and 11 years post-infection was carried out, and all memory T cell responses detected target the SARS-CoV structural proteins. Two CD8(+) T cell responses targeting the SARS-CoV membrane (M) and nucleocapsid (N) proteins were characterized by determining their HLA restriction and minimal T cell epitope regions. Furthermore, these responses were found to persist up to 11 years post-infection. An absence of cross-reactivity of these CD8(+) T cell responses against the newly-emerged Middle East respiratory syndrome coronavirus (MERS-CoV) was also demonstrated. The knowledge of the persistence of SARS-specific celullar immunity targeting the viral structural proteins in SARS-recovered individuals is important in the design and development of SARS vaccines, which are currently unavailable. PMID:26954467

  20. Protein Adsorption in Three Dimensions

    PubMed Central

    Vogler, Erwin A.

    2011-01-01

    Recent experimental and theoretical work clarifying the physical chemistry of blood-protein adsorption from aqueous-buffer solution to various kinds of surfaces is reviewed and interpreted within the context of biomaterial applications, especially toward development of cardiovascular biomaterials. The importance of this subject in biomaterials surface science is emphasized by reducing the “protein-adsorption problem” to three core questions that require quantitative answer. An overview of the protein-adsorption literature identifies some of the sources of inconsistency among many investigators participating in more than five decades of focused research. A tutorial on the fundamental biophysical chemistry of protein adsorption sets the stage for a detailed discussion of the kinetics and thermodynamics of protein adsorption, including adsorption competition between two proteins for the same adsorbent immersed in a binary-protein mixture. Both kinetics and steady-state adsorption can be rationalized using a single interpretive paradigm asserting that protein molecules partition from solution into a three-dimensional (3D) interphase separating bulk solution from the physical-adsorbent surface. Adsorbed protein collects in one-or-more adsorbed layers, depending on protein size, solution concentration, and adsorbent surface energy (water wettability). The adsorption process begins with the hydration of an adsorbent surface brought into contact with an aqueous-protein solution. Surface hydration reactions instantaneously form a thin, pseudo-2D interface between the adsorbent and protein solution. Protein molecules rapidly diffuse into this newly-formed interface, creating a truly 3D interphase that inflates with arriving proteins and fills to capacity within milliseconds at mg/mL bulk-solution concentrations CB. This inflated interphase subsequently undergoes time-dependent (minutes-to-hours) decrease in volume VI by expulsion of either-or-both interphase water and

  1. Multitemporal observations of sugarcane by TerraSAR-X images.

    PubMed

    Baghdadi, Nicolas; Cresson, Rémi; Todoroff, Pierre; Moinet, Soizic

    2010-01-01

    The objective of this study is to investigate the potential of TerraSAR-X (X-band) in monitoring sugarcane growth on Reunion Island (located in the Indian Ocean). Multi-temporal TerraSAR data acquired at various incidence angles (17°, 31°, 37°, 47°, 58°) and polarizations (HH, HV, VV) were analyzed in order to study the behaviour of SAR (synthetic aperture radar) signal as a function of sugarcane height and NDVI (Normalized Difference Vegetation Index). The potential of TerraSAR for mapping the sugarcane harvest was also studied. Radar signal increased quickly with crop height until a threshold height, which depended on polarization and incidence angle. Beyond this threshold, the signal increased only slightly, remained constant, or even decreased. The threshold height is slightly higher with cross polarization and higher incidence angles (47° in comparison with 17° and 31°). Results also showed that the co-polarizations channels (HH and VV) were well correlated. High correlation between SAR signal and NDVI calculated from SPOT-4/5 images was observed. TerraSAR data showed that after strong rains the soil contribution to the backscattering of sugarcane fields can be important for canes with heights of terminal visible dewlap (htvd) less than 50 cm (total cane heights around 155 cm). This increase in radar signal after strong rains could involve an ambiguity between young and mature canes. Indeed, the radar signal on TerraSAR images acquired in wet soil conditions could be of the same order for fields recently harvested and mature sugarcane fields, making difficult the detection of cuts. Finally, TerraSAR data at high spatial resolution were shown to be useful for monitoring sugarcane harvest when the fields are of small size or when the cut is spread out in time. The comparison between incidence angles of 17°, 37° and 58° shows that 37° is more suitable to monitor the sugarcane harvest. The cut is easily detectable on TerraSAR images for data acquired

  2. Miscible viscous fingering with linear adsorption on the porous matrix

    NASA Astrophysics Data System (ADS)

    Mishra, M.; Martin, M.; De Wit, A.

    2007-07-01

    Viscous fingering between miscible fluids of different viscosities can affect the dispersion of finite samples in porous media. In some applications, as typically in chromatographic separations or pollutant dispersion in underground aquifers, adsorption onto the porous matrix of solutes (the concentration of which rules the viscosity of the solution) can affect the fingering dynamics. Here, we investigate theoretically the influence of such an adsorption on the stability and nonlinear properties of viscous samples displaced in a two-dimensional system by a less viscous and miscible carrying fluid. The model is based on Darcy's law for the evolution of the fluid velocity coupled to a diffusion-convection equation for the concentration of a solute in the mobile phase inside the porous medium. The adsorption-desorption dynamics of the solute onto the stationary phase is assumed to be at equilibrium, to follow a linear isotherm and is characterized by a retention parameter κ' equal to the adsorption-desorption equilibrium constant K multiplied by the phase ratio F. In practice, retention on the porous matrix renormalizes the log-mobility ratio by a factor (1+κ'). Correspondingly, a linear stability analysis and nonlinear simulations of the model show that an increase of κ' leads to a stabilization of viscous fingering with fingers appearing on a dimensional time scale multiplied by (1+κ')3 and with a dimensional wavelength multiplied by (1+κ').

  3. Numerical Analysis of Orbital Perturbation Effects on Inclined Geosynchronous SAR.

    PubMed

    Dong, Xichao; Hu, Cheng; Long, Teng; Li, Yuanhao

    2016-01-01

    The geosynchronous synthetic aperture radar (GEO SAR) is susceptible to orbit perturbations, leading to orbit drifts and variations. The influences behave very differently from those in low Earth orbit (LEO) SAR. In this paper, the impacts of perturbations on GEO SAR orbital elements are modelled based on the perturbed dynamic equations, and then, the focusing is analyzed theoretically and numerically by using the Systems Tool Kit (STK) software. The accurate GEO SAR slant range histories can be calculated according to the perturbed orbit positions in STK. The perturbed slant range errors are mainly the first and second derivatives, leading to image drifts and defocusing. Simulations of the point target imaging are performed to validate the aforementioned analysis. In the GEO SAR with an inclination of 53° and an argument of perigee of 90°, the Doppler parameters and the integration time are different and dependent on the geometry configurations. Thus, the influences are varying at different orbit positions: at the equator, the first-order phase errors should be mainly considered; at the perigee and apogee, the second-order phase errors should be mainly considered; at other positions, first-order and second-order exist simultaneously. PMID:27598168

  4. Numerical Analysis of Orbital Perturbation Effects on Inclined Geosynchronous SAR

    PubMed Central

    Dong, Xichao; Hu, Cheng; Long, Teng; Li, Yuanhao

    2016-01-01

    The geosynchronous synthetic aperture radar (GEO SAR) is susceptible to orbit perturbations, leading to orbit drifts and variations. The influences behave very differently from those in low Earth orbit (LEO) SAR. In this paper, the impacts of perturbations on GEO SAR orbital elements are modelled based on the perturbed dynamic equations, and then, the focusing is analyzed theoretically and numerically by using the Systems Tool Kit (STK) software. The accurate GEO SAR slant range histories can be calculated according to the perturbed orbit positions in STK. The perturbed slant range errors are mainly the first and second derivatives, leading to image drifts and defocusing. Simulations of the point target imaging are performed to validate the aforementioned analysis. In the GEO SAR with an inclination of 53° and an argument of perigee of 90°, the Doppler parameters and the integration time are different and dependent on the geometry configurations. Thus, the influences are varying at different orbit positions: at the equator, the first-order phase errors should be mainly considered; at the perigee and apogee, the second-order phase errors should be mainly considered; at other positions, first-order and second-order exist simultaneously. PMID:27598168

  5. An automatic coastline detector for use with SAR images

    SciTech Connect

    Erteza, Ireena A.

    1998-09-01

    SAR imagery for coastline detection has many potential advantages over conventional optical stereoscopic techniques. For example, SAR does not have restrictions on being collected during daylight or when there is no cloud cover. In addition, the techniques for coastline detection witth SAR images can be automated. In this paper, we present the algorithmic development of an automatic coastline detector for use with SAR imagery. Three main algorithms comprise the automatic coastline detection algorithm, The first algorithm considers the image pre-processing steps that must occur on the original image in order to accentuate the land/water boundary. The second algorithm automatically follows along the accentuated land/water boundary and produces a single-pixel-wide coastline. The third algorithm identifies islands and marks them. This report describes in detail the development of these three algorithms. Examples of imagery are used throughout the paper to illustrate the various steps in algorithms. Actual code is included in appendices. The algorithms presented are preliminary versions that can be applied to automatic coastline detection in SAR imagery. There are many variations and additions to the algorithms that can be made to improve robustness and automation, as required by a particular application.

  6. Camouflage effectiveness of static nets in SAR images

    NASA Astrophysics Data System (ADS)

    Jersblad, Johan; Larsson, Christer

    2015-10-01

    We present a methodology to determine the camouflage effectiveness of static nets in a SAR image. There is currently no common recognized methodology within the signature management community in this research topic. One step towards establishing a common methodology is to use a standardized target to be camouflaged. We use the STANdard Decoy for CAmouflage Materials (STANDCAM) target developed by the German Army, WTD 52, Oberjettenberg. An ISAR measurement of the STANDCAM with a camouflage configuration is acquired as the first step of the method. The ISAR data is then blended with SAR data acquired in field trials. In the final SAR image a contrast metric between the target and background is extracted. The contrast measure is then the measure of the camouflage effectiveness. As an example of result we present ISAR measurements and determine the camouflage effectiveness in a SAR image using SAR blending for static nets with different electrical conductivity and design. This methodology presents a measure to determine the effectiveness of a static net on the STANDCAM target.

  7. A Localization Method for Multistatic SAR Based on Convex Optimization.

    PubMed

    Zhong, Xuqi; Wu, Junjie; Yang, Jianyu; Sun, Zhichao; Huang, Yuling; Li, Zhongyu

    2015-01-01

    In traditional localization methods for Synthetic Aperture Radar (SAR), the bistatic range sum (BRS) estimation and Doppler centroid estimation (DCE) are needed for the calculation of target localization. However, the DCE error greatly influences the localization accuracy. In this paper, a localization method for multistatic SAR based on convex optimization without DCE is investigated and the influence of BRS estimation error on localization accuracy is analysed. Firstly, by using the information of each transmitter and receiver (T/R) pair and the target in SAR image, the model functions of T/R pairs are constructed. Each model function's maximum is on the circumference of the ellipse which is the iso-range for its model function's T/R pair. Secondly, the target function whose maximum is located at the position of the target is obtained by adding all model functions. Thirdly, the target function is optimized based on gradient descent method to obtain the position of the target. During the iteration process, principal component analysis is implemented to guarantee the accuracy of the method and improve the computational efficiency. The proposed method only utilizes BRSs of a target in several focused images from multistatic SAR. Therefore, compared with traditional localization methods for SAR, the proposed method greatly improves the localization accuracy. The effectivity of the localization approach is validated by simulation experiment. PMID:26566031

  8. Modified Polar-Format Software for Processing SAR Data

    NASA Technical Reports Server (NTRS)

    Chen, Curtis

    2003-01-01

    HMPF is a computer program that implements a modified polar-format algorithm for processing data from spaceborne synthetic-aperture radar (SAR) systems. Unlike prior polar-format processing algorithms, this algorithm is based on the assumption that the radar signal wavefronts are spherical rather than planar. The algorithm provides for resampling of SAR pulse data from slant range to radial distance from the center of a reference sphere that is nominally the local Earth surface. Then, invoking the projection-slice theorem, the resampled pulse data are Fourier-transformed over radial distance, arranged in the wavenumber domain according to the acquisition geometry, resampled to a Cartesian grid, and inverse-Fourier-transformed. The result of this process is the focused SAR image. HMPF, and perhaps other programs that implement variants of the algorithm, may give better accuracy than do prior algorithms for processing strip-map SAR data from high altitudes and may give better phase preservation relative to prior polar-format algorithms for processing spotlight-mode SAR data.

  9. Targeted Radiosensitization by the Chk1 Inhibitor SAR-020106

    SciTech Connect

    Borst, Gerben R.; McLaughlin, Martin; Kyula, Joan N.; Neijenhuis, Sari; Khan, Aadil; Good, James; Zaidi, Shane; Powell, Ned G.; Meier, Pascal; Collins, Ian; Garrett, Michelle D.; Verheij, Marcel; Harrington, Kevin J.

    2013-03-15

    Purpose: To explore the activity of a potent Chk1 inhibitor (SAR-020106) in combination with radiation. Methods and Materials: Colony and mechanistic in vitro assays and a xenograft in vivo model. Results: SAR-020106 suppressed-radiation-induced G{sub 2}/M arrest and reduced clonogenic survival only in p53-deficient tumor cells. SAR-020106 promoted mitotic entry following irradiation in all cell lines, but p53-deficient cells were likely to undergo apoptosis or become aneuploid, while p53 wild-type cells underwent a postmitotic G{sub 1} arrest followed by subsequent normal cell cycle re-entry. Following combined treatment with SAR-020106 and radiation, homologous-recombination-mediated DNA damage repair was inhibited in all cell lines. A significant increase in the number of pan-γH2AX-staining apoptotic cells was observed only in p53-deficient cell lines. Efficacy was confirmed in vivo in a clinically relevant human head-and-neck cell carcinoma xenograft model. Conclusion: The Chk1 inhibitor SAR-020106 is a potent radiosensitizer in tumor cell lines defective in p53 signaling.

  10. Atmospheric Effects on InSAR Measurements and Their Mitigation

    PubMed Central

    Ding, Xiao-li; Li, Zhi-wei; Zhu, Jian-jun; Feng, Guang-cai; Long, Jiang-ping

    2008-01-01

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

  11. A Localization Method for Multistatic SAR Based on Convex Optimization

    PubMed Central

    2015-01-01

    In traditional localization methods for Synthetic Aperture Radar (SAR), the bistatic range sum (BRS) estimation and Doppler centroid estimation (DCE) are needed for the calculation of target localization. However, the DCE error greatly influences the localization accuracy. In this paper, a localization method for multistatic SAR based on convex optimization without DCE is investigated and the influence of BRS estimation error on localization accuracy is analysed. Firstly, by using the information of each transmitter and receiver (T/R) pair and the target in SAR image, the model functions of T/R pairs are constructed. Each model function’s maximum is on the circumference of the ellipse which is the iso-range for its model function’s T/R pair. Secondly, the target function whose maximum is located at the position of the target is obtained by adding all model functions. Thirdly, the target function is optimized based on gradient descent method to obtain the position of the target. During the iteration process, principal component analysis is implemented to guarantee the accuracy of the method and improve the computational efficiency. The proposed method only utilizes BRSs of a target in several focused images from multistatic SAR. Therefore, compared with traditional localization methods for SAR, the proposed method greatly improves the localization accuracy. The effectivity of the localization approach is validated by simulation experiment. PMID:26566031

  12. MAX-91: Polarimetric SAR results on Montespertoli site

    NASA Technical Reports Server (NTRS)

    Baronti, S.; Luciani, S.; Moretti, S.; Paloscia, S.; Schiavon, G.; Sigismondi, S.

    1993-01-01

    The polarimetric Synthetic Aperture Radar (SAR) is a powerful sensor for high resolution ocean and land mapping and particularly for monitoring hydrological parameters in large watersheds. There is currently much research in progress to assess the SAR operational capability as well as to estimate the accuracy achievable in the measurements of geophysical parameters with the presently available airborne and spaceborne sensors. An important goal of this research is to improve our understanding of the basic mechanisms that control the interaction of electro-magnetic waves with soil and vegetation. This can be done both by developing electromagnetic models and by analyzing statistical relations between backscattering and ground truth data. A systematic investigation, which aims at a better understanding of the information obtainable from the multi-frequency polarimetric SAR to be used in agro-hydrology, is in progress by our groups within the framework of SIR-C/X-SAR Project and has achieved a most significant milestone with the NASA/JPL Aircraft Campaign named MAC-91. Indeed this experiment allowed us to collect a large and meaningful data set including multi-temporal multi-frequency polarimetric SAR measurements and ground truth. This paper presents some significant results obtained over an agricultural flat area within the Montespertoli site, where intensive ground measurements were carried out. The results are critically discussed with special regard to the information associated with polarimetric data.

  13. Detecting and monitoring UCG subsidence with InSAR

    SciTech Connect

    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.

  14. Determining Titan surface topography from Cassini SAR data

    USGS Publications Warehouse

    Stiles, Bryan W.; Hensley, Scott; Gim, Yonggyu; Bates, David M.; Kirk, Randolph L.; Hayes, Alex; Radebaugh, Jani; Lorenz, Ralph D.; Mitchell, Karl L.; Callahan, Philip S.; Zebker, Howard; Johnson, William T.K.; Wall, Stephen D.; Lunine, Jonathan I.; Wood, Charles A.; Janssen, Michael; Pelletier, Frederic; West, Richard D.; Veeramacheneni, Chandini

    2009-01-01

    A technique, referred to as SARTopo, has been developed for obtaining surface height estimates with 10 km horizontal resolution and 75 m vertical resolution of the surface of Titan along each Cassini Synthetic Aperture Radar (SAR) swath. We describe the technique and present maps of the co-located data sets. A global map and regional maps of Xanadu and the northern hemisphere hydrocarbon lakes district are included in the results. A strength of the technique is that it provides topographic information co-located with SAR imagery. Having a topographic context vastly improves the interpretability of the SAR imagery and is essential for understanding Titan. SARTopo is capable of estimating surface heights for most of the SAR-imaged surface of Titan. Currently nearly 30% of the surface is within 100 km of a SARTopo height profile. Other competing techniques provide orders of magnitude less coverage. We validate the SARTopo technique through comparison with known geomorphological features such as mountain ranges and craters, and by comparison with co-located nadir altimetry, including a 3000 km strip that had been observed by SAR a month earlier. In this area, the SARTopo and nadir altimetry data sets are co-located tightly (within 5-10 km for one 500 km section), have similar resolution, and as expected agree closely in surface height. Furthermore the region contains prominent high spatial resolution topography, so it provides an excellent test of the resolution and precision of both techniques.

  15. Numerical Analysis of Orbital Perturbation Effects on Inclined Geosynchronous SAR.

    PubMed

    Dong, Xichao; Hu, Cheng; Long, Teng; Li, Yuanhao

    2016-09-02

    The geosynchronous synthetic aperture radar (GEO SAR) is susceptible to orbit perturbations, leading to orbit drifts and variations. The influences behave very differently from those in low Earth orbit (LEO) SAR. In this paper, the impacts of perturbations on GEO SAR orbital elements are modelled based on the perturbed dynamic equations, and then, the focusing is analyzed theoretically and numerically by using the Systems Tool Kit (STK) software. The accurate GEO SAR slant range histories can be calculated according to the perturbed orbit positions in STK. The perturbed slant range errors are mainly the first and second derivatives, leading to image drifts and defocusing. Simulations of the point target imaging are performed to validate the aforementioned analysis. In the GEO SAR with an inclination of 53° and an argument of perigee of 90°, the Doppler parameters and the integration time are different and dependent on the geometry configurations. Thus, the influences are varying at different orbit positions: at the equator, the first-order phase errors should be mainly considered; at the perigee and apogee, the second-order phase errors should be mainly considered; at other positions, first-order and second-order exist simultaneously.

  16. The Golden Ratio

    ERIC Educational Resources Information Center

    Hyde, Hartley

    2004-01-01

    The Golden Ratio is sometimes called the "Golden Section" or the "Divine Proportion", in which three points: A, B, and C, divide a line in this proportion if AC/AB = AB/BC. "Donald in Mathmagicland" includes a section about the Golden Ratio and the ratios within a five-pointed star or pentagram. This article presents two computing exercises that…

  17. SAR image registration in absolute coordinates using GPS carrier phase position and velocity information

    SciTech Connect

    Burgett, S.; Meindl, M.

    1994-09-01

    It is useful in a variety of military and commercial application to accurately register the position of synthetic aperture radar (SAR) imagery in absolute coordinates. The two basic SAR measurements, range and doppler, can be used to solve for the position of the SAR image. Imprecise knowledge of the SAR collection platform`s position and velocity vectors introduce errors in the range and doppler measurements and can cause the apparent location of the SAR image on the ground to be in error by tens of meters. Recent advances in carrier phase GPS techniques can provide an accurate description of the collection vehicle`s trajectory during the image formation process. In this paper, highly accurate carrier phase GPS trajectory information is used in conjunction with SAR imagery to demonstrate a technique for accurate registration of SAR images in WGS-84 coordinates. Flight test data will be presented that demonstrates SAR image registration errors of less than 4 meters.

  18. 29. SAR2, VIEW TO NORTH WITH EXCITERS AT LEFT. SCE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. SAR-2, VIEW TO NORTH WITH EXCITERS AT LEFT. SCE negative no. 1043, photographed June 6, 1912. Photograph by G. Haven Bishop. - Santa Ana River Hydroelectric System, SAR-2 Powerhouse, Redlands, San Bernardino County, CA

  19. Results of the sub-thirty-pound high-resolution miniSAR demonstration

    NASA Astrophysics Data System (ADS)

    Dubbert, Dale F.; Sweet, April D.; Sloan, George R.; Doerry, Armin W.

    2006-05-01

    Sandia-developed SAR systems are well known for their real-time, high quality, high resolution imagery. One such system, the General Atomics Lynx radar, has been successfully demonstrated on medium-payload UAVs, including the Predator and Fire Scout. Previously, Sandia reported on its system concept and roadmap for SAR miniaturization, including details of the miniSAR program. This paper and its companions provide an update for miniSAR and discuss the results of the successful May 2005 demonstration of the 26 pound, 4-inch resolution system. Accordingly, the miniSAR system and software implementation and performance are reviewed. Additionally, future plans for miniSAR and the Sandia SAR/GMTI miniaturization efforts are discussed, such as the currently planned miniSAR demonstration onboard a small-payload UAV.

  20. 37. SAR2, SHOWING OIL CIRCUIT BREAKERS (ABOVE) AND GENERATOR FIELD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. SAR-2, SHOWING OIL CIRCUIT BREAKERS (ABOVE) AND GENERATOR FIELD COIL CONTROL RHEOSTATS (BELOW). SCE negative no. 10331, November 1, 1923. Photograph by G. Haven Bishop. - Santa Ana River Hydroelectric System, SAR-2 Powerhouse, Redlands, San Bernardino County, CA

  1. 1. DOMESTIC WATER SUPPLY TREATMENT HOUSE, ON PENSTOCK ABOVE SAR1. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. DOMESTIC WATER SUPPLY TREATMENT HOUSE, ON PENSTOCK ABOVE SAR-1. VIEW TO NORTWEST. - Santa Ana River Hydroelectric System, SAR-1 Domestic Water Supply Treatment House, Redlands, San Bernardino County, CA

  2. 36. SAR1 UNDER CONSTRUCTION, WITH WORKERS ATOP CRANE. EEC print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    36. SAR-1 UNDER CONSTRUCTION, WITH WORKERS ATOP CRANE. EEC print no. N-C-01-00031, no date. Photograph by Benjamin F. Pearson. - Santa Ana River Hydroelectric System, SAR-1 Powerhouse, Redlands, San Bernardino County, CA

  3. 12. OVERVIEW FROM FORMER RESIDENTIAL AREA NORTH OF SAR2, SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. OVERVIEW FROM FORMER RESIDENTIAL AREA NORTH OF SAR-2, SHOWING TRAIL UP TO FOREBAY, RETAINING WALL, PEPPER TREES, AND SAR-2 IN DISTANCE. VIEW TO SOUTH-SOUTHEAST. - Santa Ana River Hydroelectric System, Redlands, San Bernardino County, CA

  4. Equilibrium and kinetic data and process design for adsorption of Congo Red onto bentonite.

    PubMed

    Bulut, Emrah; Ozacar, Mahmut; Sengil, I Ayhan

    2008-06-15

    The adsorption of Congo Red onto bentonite in a batch adsorber has been studied. Four kinetic models, the pseudo first- and second-order equations, the Elovich equation and the intraparticle diffusion equation, were selected to follow the adsorption process. Kinetic parameters; rate constants, equilibrium adsorption capacities and correlation coefficients, for each kinetic equation were calculated and discussed. It was shown that the adsorption of Congo Red onto bentonite could be described by the pseudo second-order equation. The experimental isotherm data were analyzed using the Langmuir, Freundlich and Temkin equations. Adsorption of Congo Red onto bentonite followed the Langmuir isotherm. A single stage batch adsorber was designed for different adsorbent mass/treated effluent volume ratios using the Langmuir isotherm. PMID:18055111

  5. Transient Surface Deformation of Northern Taiwan, 2007-2011, Using Persistent Scattered InSAR with ALOS Data

    NASA Astrophysics Data System (ADS)

    Wang, C.; Chang, W.; Chang, C.

    2013-12-01

    The Taipei basin, triangular in shape and located in the northern Taiwan, is now developed into the most densely populated area and also the capital of politics and economics in Taiwan. North of the Taipei basin, the Tatun volcano group was proposed to be the cause of extensional collapse during the Pleistocene following the collision between the Luzon volcanic arc and the Eurasian continental margin at about 5 Ma. We investigated the contemporary surface deformation of the northern Taiwan using ALOS images that cover the Taipei basin and its surrounding mountainous area. The Differential Interferometric Synthetic Aperture Radar (DInSAR) technique has been widely used in the past ten years. However, the mountainous areas surrounding the basin are mostly covered with densely various vegetations that reduce signal-to-noise ratio in the interferograms. Therefore, the DInSAR technique is not effective for measuring the surface deformation in and around the Taipei basin, including the Tatun volcano area, and consequently the Persistent Scatterer (PS) and small baseline (SB) InSAR techniques have been employed to extract phase signals of the chosen PS points. In this study, we aim to measure the ground deformation of northern Taiwan by processing the spaceborne radar interferometry data of ALOS acquired from 2007 to 2011 using PSInSAR and SBInSAR techniques. Compared with the Envisat and ERS images used by previous studies, L-band PALSAR images can produce more PS points in the region covered by dense vegetation so that our results reveal a higher resolution of ground deformation. The mean Line of Sight (LOS) velocity field of up to 8 mm/yr in the central Tatun volcanic area, and up to 5 mm/yr in the Taipei basin with higher rate at the hanging wall of the Sanchiao fault than the footwall. (See the Figure.) While previous studies indicated that the Taipei basin had experienced ground uplift from 1993 to 2001 and subsidence from 2003 to 2008, our results show a return to

  6. Limitation on the use of a spaceborne SAR for rain measurements

    NASA Technical Reports Server (NTRS)

    Ahamad, Atiq

    1994-01-01

    A proof-of-concept experiment for remote sensing of precipitation by SAR is part of the SIR-C/X-SAR experiment. This thesis presents a feasibility study and recommendations for detection of precipitation using SIR-C/X-SAR. The principal limitation to rain measurement from a spaceborne SAR is the poor SCR (signal-to-clutter ratio). This is in part due to the system configuration and largely due to the large magnitude of echoes associated with the surface component. Two geometries apply: off-vertical and vertical pointing angles. Here we present calculations for both. With vertical geometry a large clutter component is associated with range sidelobes of the chirped transmitter pulse. To overcome this problem a narrow transmitted pulse (3 mu sec) processed without dechirping was used. Since the magnitude of the clutter over the ocean is high it is recommended that data in the chirped mode be obtained over the forest due to the significantly lower backscatter associated with it at nadir. With these recommendations, at nadir, it is believed that rain rates greater than 5 mm/hr may be detected. The use of a better weighting function that gives lower sidelobe levels than that used (a raised cos(exp 2)) is also recommended. At off-vertical look angles all the range cells have a large clutter component associated with them due to the geometry. The use of higher angles of incidence (theta greater than 60 deg) is recommended because of better SCR at these angles. With this recommendation, at off-vertical, it is believed that rain rates greater than 10 mm/hr may be detected. Various other techniques are described and recommended to improve the minimum detectable precipitation rate. These include trying to subtract the estimate of the clutter from the combined signal and clutter and trying to separate the Doppler of the rain echo and the surface echo. With these recommendations it is believed that it is possible to detect precipitation as low as 1 mm/hr at vertical and greater

  7. A single-channel 10-bit 160 MS/s SAR ADC in 65 nm CMOS

    NASA Astrophysics Data System (ADS)

    Yuxiao, Lu; Lu, Sun; Zhe, Li; Jianjun, Zhou

    2014-04-01

    This paper demonstrates a single-channel 10-bit 160 MS/s successive-approximation-register (SAR) analog-to-digital converter (ADC) in 65 nm CMOS process with a 1.2 V supply voltage. To achieve high speed, a new window-opening logic based on the asynchronous SAR algorithm is proposed to minimize the logic delay, and a partial set-and-down DAC with binary redundancy bits is presented to reduce the dynamic comparator offset and accelerate the DAC settling. Besides, a new bootstrapped switch with a pre-charge phase is adopted in the track and hold circuits to increase speed and reduce area. The presented ADC achieves 52.9 dB signal-to-noise distortion ratio and 65 dB spurious-free dynamic range measured with a 30 MHz input signal at 160 MHz clock. The power consumption is 9.5 mW and a core die area of 250 × 200 μm2 is occupied.

  8. Selection Maintains Low Genomic GC Content in Marine SAR11 Lineages.

    PubMed

    Luo, Haiwei; Thompson, Luke R; Stingl, Ulrich; Hughes, Austin L

    2015-10-01

    The genomic G+C content of ocean bacteria varies from below 30% to over 60%. This broad range of base composition is likely shaped by distinct mutational processes, recombination, effective population size, and selection driven by environmental factors. A number of studies have hypothesized that depletion of G/C in genomes of marine bacterioplankton cells is an adaptation to the nitrogen-poor pelagic oceans, but they failed to disentangle environmental factors from mutational biases and population history. Here, we reconstructed the evolutionary changes of bases at synonymous sites in genomes of two marine SAR11 populations and a freshwater counterpart with its evolutionary origin rooted in the marine lineage. Although they all have similar genome sizes, DNA repair gene repertoire, and base compositions, there is a stronger bias toward A/T changes, a reduced frequency of nitrogenous amino acids, and an exclusive occurrence of polyamine, opine, and taurine transport systems in the ocean populations, consistent with a greater nitrogen stress in surface oceans compared with freshwater lakes. Furthermore, the ratio of nonsynoymous to synonymous nucleotide diversity is not statistically distinguishable among these populations, suggesting that population history has a limited effect. Taken together, the ecological transition of SAR11 from ocean to freshwater habitats makes nitrogen more available to these organisms, and thus relaxation of purifying selection drove a genome-wide reduction in the frequency of G/C to A/T changes in the freshwater population.

  9. SweepSAR: Beam-forming on Receive Using a Reflector-Phased Array Feed Combination for Spaceborne SAR

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Krieger, G.; Rosen, P.; Younis, M.; Johnson, W. T. K.; Huber, S.; Jordan, R.; Moreira, A.

    2012-01-01

    In this paper, an alternative approach is described that is suited for longer wavelength SARs in particular, employing a large, deployable reflector antenna and a much simpler phased array feed. To illuminate a wide swath, a substantial fraction of the phased array feed is excited on transmit to sub-illuminate the reflector. Shorter transmit pulses are required than for conventional SAR. On receive, a much smaller portion of the phased array feed is used to collect the return echo, so that a greater portion of the reflector antenna area is used. The locus of the portion of the phased array used on receive is adjusted using an analog beam steering network, to 'sweep' the receive beam(s) across the illuminated swath, tracking the return echo. This is similar in some respects to the whiskbroom approach to optical sensors, hence the name: SweepSAR.SweepSAR has advantages over conventional SAR in that it requires less transmit power, and if the receive beam is narrow enough, it is relatively immune to range ambiguities. Compared to direct radiating arrays with digital beam- forming, it is much simpler to implement, uses currently available technologies, is better suited for longer wavelength systems, and does not require extremely high data rates or onboard processing.

  10. Polarimetric SAR Models for Oil Fields Monitoring in China Seas

    NASA Astrophysics Data System (ADS)

    Buono, A.; Nunziata, F.; Li, X.; Wei, Y.; Ding, X.

    2014-11-01

    In this study, physical-based models for polarimetric Synthetic Aperture Radar (SAR) oil fields monitoring are proposed. They all share a physical rationale relying on the different scattering mechanisms that characterize a free sea surface, an oil slick-covered sea surface, and a metallic target. In fact, sea surface scattering is well modeled by a Bragg-like behaviour, while a strong departure from Bragg scattering is in place when dealing with oil slicks and targets. Furthermore, the proposed polarimetric models aim at addressing simultaneously target and oil slick detection, providing useful extra information with respect to single-pol SAR data in order to approach oil discrimination and classification. Experiments undertaken over East and South China Sea from actual C-band RadarSAT-2 full-pol SAR data witness the soundness of the proposed rationale.

  11. SAR imaging for a forward-looking GPR system

    NASA Astrophysics Data System (ADS)

    Liu, Guoqing; Wang, Yanwei; Li, Jian; Bradley, Marshall R.

    2003-09-01

    We investigate both two-dimensional (2-D) and three-dimensional (3-D) synthetic aperture radar (SAR) imaging techniques for a forward-looking ground penetrating radar (FLGPR) system. In particular, we consider SAR imaging using the delay-and-sum (DAS), phase-shift migration, and spectral estimation (joint APES (Amplitude and Phase EStimation) and RCB (Robust Capon Beamforming)) approaches with the PSI (Planning Systems Inc.) FLGPR Phase II system. For the DAS and phase-shift migration approaches, we use shading in both frequency and cross-track aperture dimensions to reduce sidelobe leakages and clutter. We perform both coherent and non-coherent multi-look processing as well as smoothing to improve the SAR imaging quality and landmine detection capability of the system. The effectiveness of the approaches are demonstrated with an experimental data set collected by the PSI FLGPR Phase II system.

  12. Analysis of motion disambiguation using multi-channel circular SAR

    NASA Astrophysics Data System (ADS)

    Fasih, Ahmed R.; Rossler, Carl W.; Ash, Joshua N.; Moses, Randolph L.

    2010-04-01

    Combining moving target indication (MTI) radar with synthetic aperture radar (SAR) is of great interest to radar specialists, in terms of improving multiple-target tracking in large, urban scenes. A major obstacle to such a merger are ambiguities induced by mution. Using statistical bounds we quantify the improvement of moving target localization with multi-channel SAR over single-channel SAR and the more traditional MTI technique of displaced phase center array (DPCA) processing. We show that the potential for substantial improvements in localization performance is borne out by practical estimators based on sparse reconstruction algorithms, whose performance approach statistical bounds, even under clutter. We also outline a parallelization scheme for the nonquadratic regularized sparse reconstruction technique to utilize clusters for processing large datasets.

  13. Metamaterial-Embedded Low SAR PIFA for Cellular Phone.

    PubMed

    Faruque, M R I; Hossain, M I; Misran, N; Singh, M; Islam, M T

    2015-01-01

    A metamaterial-embedded planar inverted-F antenna (PIFA) is proposed in this study for cellular phone applications. A dual-band PIFA is designed to operate both GSM 900 MHz and DCS 1800 MHz. The ground plane of a conventional PIFA is modified using a planar one-dimensional metamaterial array. The investigation is performed using the Finite Integration Technique (FIT) of CST Microwave Studio. The performance of the developed antenna was measured in an anechoic chamber. The specific absorption rate (SAR) values are calculated considering two different holding positions: cheek and tilt. The SAR values are measured using COMOSAR measurement system. Good agreement is observed between the simulated and measured data. The results indicate that the proposed metamaterial-embedded antenna produces significantly lower SAR in the human head compared to the conventional PIFA. Moreover, the modified antenna substrate leads to slight improvement of the antenna performances.

  14. Theory and measure of certain image norms in SAR

    NASA Technical Reports Server (NTRS)

    Raney, R. K.

    1984-01-01

    The principal properties of synthetic aperture radar SAR imagery of point and distributed objects are summarized. Against this background, the response of a SAR (Synthetic Aperture Radar) to the moving surface of the sea is considered. Certain conclusions are drawn as to the mechanism of interaction between microwaves and the sea surface. Focus and speckle spectral tests may be used on selected SAR imagery for areas of the ocean. The fine structure of the sea imagery is sensitive to processor focus and adjustment. The ocean reflectivity mechanism must include point like scatterers of sufficient radar cross section to dominate the return from certain individual resolution elements. Both specular and diffuse scattering mechanisms are observed together, to varying degree. The effect is sea state dependent. Several experiments are proposed based on imaging theory that could assist in the investigation of reflectivity mechanisms.

  15. Metamaterial-Embedded Low SAR PIFA for Cellular Phone

    PubMed Central

    Faruque, M. R. I.; Hossain, M. I.; Misran, N.; Singh, M.; Islam, M. T.

    2015-01-01

    A metamaterial-embedded planar inverted-F antenna (PIFA) is proposed in this study for cellular phone applications. A dual-band PIFA is designed to operate both GSM 900 MHz and DCS 1800 MHz. The ground plane of a conventional PIFA is modified using a planar one-dimensional metamaterial array. The investigation is performed using the Finite Integration Technique (FIT) of CST Microwave Studio. The performance of the developed antenna was measured in an anechoic chamber. The specific absorption rate (SAR) values are calculated considering two different holding positions: cheek and tilt. The SAR values are measured using COMOSAR measurement system. Good agreement is observed between the simulated and measured data. The results indicate that the proposed metamaterial-embedded antenna produces significantly lower SAR in the human head compared to the conventional PIFA. Moreover, the modified antenna substrate leads to slight improvement of the antenna performances. PMID:26599584

  16. A new FOA estimation method in SAR/GALILEO system

    NASA Astrophysics Data System (ADS)

    Liu, Gang; He, Bing; Li, Jilin

    2007-11-01

    The European Galileo Plan will include the Search and Rescue (SAR) transponder which will become part of the future MEOSAR (Medium earth orbit Search and Rescue) system, the new SAR system can improve localization accuracy through measuring the frequency of arrival (FOA) and time of arrival (TOA) of beacons, the FOA estimation is one of the most important part. In this paper, we aim to find a good FOA algorithm with minimal estimation error, which must be less than 0.1Hz. We propose a new method called Kay algorithm for the SAR/GALILEO system by comparing some frequency estimation methods and current methods using in the COAPAS-SARSAT system and analyzing distress beacon in terms of signal structure, spectrum characteristic. The simulation proves that the Kay method for FOA estimation is better.

  17. Unsupervised Change Detection in SAR Images Using Gaussian Mixture Models

    NASA Astrophysics Data System (ADS)

    Kiana, E.; Homayouni, S.; Sharifi, M. A.; Farid-Rohani, M.

    2015-12-01

    In this paper, we propose a method for unsupervised change detection in Remote Sensing Synthetic Aperture Radar (SAR) images. This method is based on the mixture modelling of the histogram of difference image. In this process, the difference image is classified into three classes; negative change class, positive change class and no change class. However the SAR images suffer from speckle noise, the proposed method is able to map the changes without speckle filtering. To evaluate the performance of this method, two dates of SAR data acquired by Uninhabited Aerial Vehicle Synthetic from an agriculture area are used. Change detection results show better efficiency when compared to the state-of-the-art methods.

  18. Polar format algorithm for SAR imaging with Matlab

    NASA Astrophysics Data System (ADS)

    Deming, Ross; Best, Matthew; Farrell, Sean

    2014-06-01

    Due to its computational efficiency, the polar format algorithm (PFA) is considered by many to be the workhorse for airborne synthetic aperture radar (SAR) imaging. PFA is implemented in spatial Fourier space, also known as "K-space", which is a convenient domain for understanding SAR performance metrics, sampling requirements, etc. In this paper the mathematics behind PFA are explained and computed examples are presented, both using simulated data, and experimental airborne radar data from the Air Force Research Laboratory (AFRL) Gotcha Challenge collect. In addition, a simple graphical method is described that can be used to model and predict wavefront curvature artifacts in PFA imagery, which are due to the limited validity of the underlying far-field approximation. The appendix includes Matlab code for computing SAR images using PFA.

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

    SciTech Connect

    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.

  20. Ensemble polarimetric SAR image classification based on contextual sparse representation

    NASA Astrophysics Data System (ADS)

    Zhang, Lamei; Wang, Xiao; Zou, Bin; Qiao, Zhijun

    2016-05-01

    Polarimetric SAR image interpretation has become one of the most interesting topics, in which the construction of the reasonable and effective technique of image classification is of key importance. Sparse representation represents the data using the most succinct sparse atoms of the over-complete dictionary and the advantages of sparse representation also have been confirmed in the field of PolSAR classification. However, it is not perfect, like the ordinary classifier, at different aspects. So ensemble learning is introduced to improve the issue, which makes a plurality of different learners training and obtained the integrated results by combining the individual learner to get more accurate and ideal learning results. Therefore, this paper presents a polarimetric SAR image classification method based on the ensemble learning of sparse representation to achieve the optimal classification.

  1. SAR target classification based on multiscale sparse representation

    NASA Astrophysics Data System (ADS)

    Ruan, Huaiyu; Zhang, Rong; Li, Jingge; Zhan, Yibing

    2016-03-01

    We propose a novel multiscale sparse representation approach for SAR target classification. It firstly extracts the dense SIFT descriptors on multiple scales, then trains a global multiscale dictionary by sparse coding algorithm. After obtaining the sparse representation, the method applies spatial pyramid matching (SPM) and max pooling to summarize the features for each image. The proposed method can provide more information and descriptive ability than single-scale ones. Moreover, it costs less extra computation than existing multiscale methods which compute a dictionary for each scale. The MSTAR database and ship database collected from TerraSAR-X images are used in classification setup. Results show that the best overall classification rate of the proposed approach can achieve 98.83% on the MSTAR database and 92.67% on the TerraSAR-X ship database.

  2. 3-D Target Location from Stereoscopic SAR Images

    SciTech Connect

    DOERRY,ARMIN W.

    1999-10-01

    SAR range-Doppler images are inherently 2-dimensional. Targets with a height offset lay over onto offset range and azimuth locations. Just which image locations are laid upon depends on the imaging geometry, including depression angle, squint angle, and target bearing. This is the well known layover phenomenon. Images formed with different aperture geometries will exhibit different layover characteristics. These differences can be exploited to ascertain target height information, in a stereoscopic manner. Depending on the imaging geometries, height accuracy can be on the order of horizontal position accuracies, thereby rivaling the best IFSAR capabilities in fine resolution SAR images. All that is required for this to work are two distinct passes with suitably different geometries from any plain old SAR.

  3. Parallel algorithms for high-speed SAR processing

    NASA Astrophysics Data System (ADS)

    Mallorqui, Jordi J.; Bara, Marc; Broquetas, Antoni; Wis, Mariano; Martinez, Antonio; Nogueira, Leonardo; Moreno, Victoriano

    1998-11-01

    The mass production of SAR products and its usage on monitoring emergency situations (oil spill detection, floods, etc.) requires high-speed SAR processors. Two different parallel strategies for near real time SAR processing based on a multiblock version of the Chirp Scaling Algorithm (CSA) have been studied. The first one is useful for small companies that would like to reduce computation times with no extra investment. It uses a cluster of heterogeneous UNIX workstations as a parallel computer. The second one is oriented to institutions, which have to process large amounts of data in short times and can afford the cost of large parallel computers. The parallel programming has reduced in both cases the computational times when compared with the sequential versions.

  4. Acousto-optic/CCD real-time SAR data processor

    NASA Technical Reports Server (NTRS)

    Psaltis, D.

    1983-01-01

    The SAR processor which uses an acousto-optic device as the input electronic-to-optical transducer and a 2-D CCD image sensor, which is operated in the time-delay-and-integrate (TDI) mode is presented. The CCD serves as the optical detector, and it simultaneously operates as an array of optically addressed correlators. The lines of the focused SAR image form continuously (at the radar PRF) at the final row of the CCD. The principles of operation of this processor, its performance characteristics, the state-of-the-art of the devices used and experimental results are outlined. The methods by which this processor can be made flexible so that it can be dynamically adapted to changing SAR geometries is discussed.

  5. Metamaterial-Embedded Low SAR PIFA for Cellular Phone.

    PubMed

    Faruque, M R I; Hossain, M I; Misran, N; Singh, M; Islam, M T

    2015-01-01

    A metamaterial-embedded planar inverted-F antenna (PIFA) is proposed in this study for cellular phone applications. A dual-band PIFA is designed to operate both GSM 900 MHz and DCS 1800 MHz. The ground plane of a conventional PIFA is modified using a planar one-dimensional metamaterial array. The investigation is performed using the Finite Integration Technique (FIT) of CST Microwave Studio. The performance of the developed antenna was measured in an anechoic chamber. The specific absorption rate (SAR) values are calculated considering two different holding positions: cheek and tilt. The SAR values are measured using COMOSAR measurement system. Good agreement is observed between the simulated and measured data. The results indicate that the proposed metamaterial-embedded antenna produces significantly lower SAR in the human head compared to the conventional PIFA. Moreover, the modified antenna substrate leads to slight improvement of the antenna performances. PMID:26599584

  6. Nonlocal means SAR image despeckling using Principle Neighborhood Dictionaries

    NASA Astrophysics Data System (ADS)

    Zhong, Hua; Yang, Chen; Jiao, L. C.

    2011-11-01

    The Principle Neighborhood Dictionary (PND) filter projects the image patches onto a lower dimensional subspace using Principle Component analysis (PCA), based on which the similarity measure of image patch can be computed with a higher accuracy for the nonlocal means (NLM) algorithm. In this paper, a new PND filter for synthetic aperture radar (SAR) image despeckling is presented, in which a new distance that adapts to the multiplicative speckle noise is derived. Compared with the commonly used Euclidean distance in NLM, the new distance measure improves the accuracy of the similarity measure of speckled patches in SAR images. The proposed method is validated on simulated and real SAR images through comparisons with other classical despeckling methods.

  7. Modelling Iteration Convergence Condition for Single SAR Image Geocoding

    NASA Astrophysics Data System (ADS)

    Dong, Yuting; Liao, Minghsheng; Zhang, Lu; Shi, Xuguo

    2014-11-01

    Single SAR image geocoding is to determine the ground coordinate for each pixel in the SAR image assisted with an external DEM. Due to the uncertainty of the elevation of each pixel in SAR image, an iterative procedure is needed, which suffers from the problem of divergence in some difficult areas such as shaded and serious layover areas. This paper aims at theoretically analysing the convergence conditions that has not been intensively studied till now. To make the discussion easier, the Range-Doppler (RD) model is simplified and then the general surface is simplified into a planar surface. Mathematical deduction is carried out to derive the convergence conditions and the impact factors for the convergence speed are analysed. The theoretical findings are validated by experiments for both simulated and real surfaces.

  8. Adsorption of lanthanum to goethite in the presence of gluconate

    SciTech Connect

    Hull, Laurence C.; Sarah Pepper; Sue Clark

    2005-05-01

    Adsorption of Lanthanum to Goethite in the Presence of Gluconic Acid L. C. HULL,1 S. E. PEPPER2 AND S. B. CLARK2 1Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID (hulllc@inel.gov) 2Washington State University, Pullman, WA (spepper@wsu.edu), (s_clark@wsu.edu) Lanthanide and trivalent-actinide elements in radioactive waste can pose risks to humans and ecological systems for many years. Organic complexing agents, from natural organic matter or the degradation of waste package components, can alter the mobility of these elements. We studied the effect of gluconic acid, as an analogue for cellulose degradation products, on the adsorption of lanthanum, representing lanthanide and trivalent-actinide elments, to goethite, representing natural iron minearals and degradation products of waste packages. Batch pH adsorption edge experiments were conducted with lanthanum alone, and with lanthanum and gluconate at a 1:1 mole ratio. Lanthanum concentrations studied were 0.1, 1, and 10 mM, covering a range from 10% to 1000% of the calculated available adsorption sites on goethite. In the absence of gluconate, lanthanum was primarily present in solution as free lanthanum ion. With gluconate present, free lanthanum concentration in solution decreased with increasing pH as step-wise deprotonation of the gluconate molecule increased the fraction lanthanum complexed with gluconate. Adsorption to the goethite surface was represented with the diffuse double-layer model. The number of adsorption sites and the intrinsic binding constants for the surface complexes were estimated from the pH adsorption edge data using the computer code FITEQL 4.0. Two surface reactions were used to fit the adsorption data in the absence of gluconate. A strong binding site with no proton release and a much higher concentration of weak binding sites with release of two protons per lanthanum adsorbed. The adsorption of lanthanum was not measurably affected by the presence of gluconate

  9. Fear of Severe Acute Respiratory Syndrome (SARS) among Health Care Workers

    ERIC Educational Resources Information Center

    Ho, Samuel M. Y.; Kwong-Lo, Rosalie S. Y.; Mak, Christine W. Y.; Wong, Joe S.

    2005-01-01

    In this study, the authors examined fear related to severe acute respiratory syndrome (SARS) among 2 samples of hospital staff in Hong Kong. Sample 1 included health care workers (n = 82) and was assessed during the peak of the SARS epidemic. Sample 2 included hospital staff who recovered from SARS (n = 97). The results show that participants in…

  10. 76 FR 20822 - Proposed Information Collection (Servicer's Staff Appraisal Reviewer (SAR) Application) Activity...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-13

    ... approval as Staff Appraisal Reviewer (SAR). Servicers SAR's will have the authority to review real estate... AFFAIRS Proposed Information Collection (Servicer's Staff Appraisal Reviewer (SAR) Application) Activity... needed to nominate servicer appraisal employee as a staff appraisal reviewer. DATES: Written comments...

  11. 76 FR 27387 - Agency Information Collection Activity (Lenders Staff Appraisal Reviewer (SAR) Application) Under...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-11

    ... approved, SARs will have the authority to review real estate appraisals and to issue notices of values on... AFFAIRS Agency Information Collection Activity (Lenders Staff Appraisal Reviewer (SAR) Application) Under....'' Title: Lenders Staff Appraisal Reviewer (SAR) Application, VA Form 26-0785. OMB Control Number:...

  12. 76 FR 35949 - Agency Information Collection Activity (Servicer's Staff Appraisal Reviewer (SAR) Application...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-20

    ...). Servicers SAR's will have the authority to review real estate appraisals and to issue liquidation notices of... AFFAIRS Agency Information Collection Activity (Servicer's Staff Appraisal Reviewer (SAR) Application....'' SUPPLEMENTARY INFORMATION: ] Title: Servicer's Staff Appraisal Reviewer (SAR) Application, VA Form 26-0829....

  13. A SAR-ADC using unit bridge capacitor and with calibration for the front-end electronics of PET imaging

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Wei, Tingcun; Li, Bo; Yang, Lifeng; Xue, Feifei; Hu, Yongcai

    2016-05-01

    This paper presents a 12-bit 1 MS/s successive approximation register-analog to digital converter (SAR-ADC) for the 32-channel front-end electronics of CZT-based PET imaging system. To reduce the capacitance mismatch, instead of the fractional capacitor, the unit capacitor is used as the bridge capacitor in the split-capacitor digital to analog converter (DAC) circuit. In addition, in order to eliminate the periodical DNL errors of -1 LSB which often exists in the SAR-ADC using the charge-redistributed DAC, a calibration algorithm is proposed and verified by the experiments. The proposed 12-bit 1 MS/s SAR-ADC is designed and implemented using a 0.35 μm CMOS technology, it occupies only an active area of 986×956 μm2. The measurement results show that, at the power supply of 3.3/5.0 V and the sampling rate of 1 MS/s, the ADC with calibration has a signal-to-noise-and-distortion ratio (SINAD) of 67.98 dB, the power dissipation of 5 mW, and a figure of merit (FOM) of 2.44 pJ/conv.-step. This ADC is with the features of high accuracy, low power and small layout area, it is especially suitable to the one-chip integration of the front-end readout electronics.

  14. Expanded and packed bed albumin adsorption on fluoride modified zirconia.

    PubMed

    Mullick, A; Griffith, C M; Flickinger, M C

    1998-11-01

    The expanded bed characteristics of 75-103microm fluoride-modified zirconia (FmZr) particles synthesized by a fed batch oil emulsion process were investigated. These particles are distinguished from commercially available expanded-bed adsorbents by virtue of their high density (2.8 g/cc) and the mixed mode protein retention mechanism which allows for the retention of both cationic and anionic proteins. The linear velocity versus bed porosity data agree with the Richardson-Zaki relationship with the terminal velocity in infinite medium of 2858.4 cm/h and a bed expansion index of 5.1. Residence time distribution (RTD) studies and bovine serum albumin (BSA) adsorption studies were performed as a function of the height of the settled bed to the column diameter (H:D) ratio and degree of bed expansion with superficial velocities of 440 to 870 cm/h. The settled bed, a 2x expanded bed, and a 3x expanded bed were studied for the H:D ratios of 1:1, 2:1, and 3:1. The dynamic binding capacity (DBC) at 5% breakthrough was low (2-8 mg BSA/mL settled bed) and was independent of the H:D ratio or the degree of bed expansion. The saturation DBC was 32.3 +/- 7.0 mg BSA/mL settled bed. The adsorption-desorption kinetics and intraparticle diffusion for protein adsorption on FmZr (38-75 micrometer) were investigated by studying the packed bed RTD and BSA adsorption as a function of temperature and flow rate. The data show that the adsorption-desorption kinetics along with intraparticle diffusion significantly influence protein adsorption on FmZr. Low residence times ( approximately 0.8 min) of BSA result in a DBC at 5% breakthrough which is 3.5-fold lower compared to that at 6-fold higher protein residence time. At low linear velocity (45 cm/h) the breakthrough curve is nearly symmetrical and becomes asymmetrical and more dispersed at higher linear velocity (270 cm/h) due to the influence of slow adsorption-desorption kinetics and intraparticle diffusion. Bioeng 60: 333-340, 1998. PMID

  15. A no-calorimetric method for measuring SAR in MRI

    NASA Astrophysics Data System (ADS)

    Romano, Rocco; Acernese, Fausto; Barone, Fabrizio

    2011-04-01

    During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2 - 33). The phase transition method is a new no-calorimetric method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement. On the other hand, it is necessary to establish if all deposited power SAR can be considered acquired and measured. In this paper, that will be shown.

  16. The phase transition method for SAR measurement in MRI

    NASA Astrophysics Data System (ADS)

    Romano, R.; Canonico, R.; Acernese, F.; Giordano, G.; Barone, F.

    2014-03-01

    During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2 - 33). The phase transition method is a new method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement. Nevertheless, in order to consider this method it is necessary to verify that all deposited SAR power can be considered acquired and measured. In this paper considerations about this aspect are conducted.

  17. The phase transition method for SAR measurement in MRI

    NASA Astrophysics Data System (ADS)

    Romano, Rocco; Acernese, Fausto; Vilasi, Silvia; Barone, Fabrizio

    2010-03-01

    During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2 - 33). The phase transition method is a new method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement. On the other hand, it is necessary to establish if all deposited power SAR can be considered acquired and measured. In this paper, that will be shown.

  18. Airborne SAR/IFSAR for mapping in urban areas

    NASA Astrophysics Data System (ADS)

    Chayakula, Thongthit

    There are many problems in topographic mapping in an urban area. Traditional land survey is a very time consuming technique and can be very expensive. Photogrammetry is a popular choice but there are some problems such as clouds and limited operational time. Since Synthetic Aperture Radar, (SAR), is an active remote sensing system and its signal can penetrate through clouds, it can be operated at any time of day and is a independent of the weather. SAR could be a good solution for topographic mapping in an urban area. Combining SAR data and Interferometric radar technology can provide enough information for topographic mapping. Information can be extracted from SAR intensity Image. This thesis focuses on feature extraction and classification for topographic mapping in an urban area from airborne interferometric SAR data. A new algorithm is described which is simple and practical but yet very efficient for feature extraction and for object-based feature classification. An adapted Canny-Petrou-Kittler algorithm is applied for edge detection. Since the algorithm provides good detection, good localization and only one response to a single edge, it is an ideal edge detection for dense urban areas. Since the SAR image is noisy by its nature, small weak edges are expected. The modified non-maximal technique is also proposed to reduce unwanted edge. The technique of generation of bald earth DEM is proposed to obtain a normalised DEM for feature extraction. Region growing from edge detection is then applied to extract a more accurate shape of the feature and generate feature surface by using topographic parameters. The extracted feature is then classified by object-oriented classification technique, in which the classification is performed at object level not pixel level. And at the end of the process 3D city model can be produced.

  19. Sparsity-driven autofocus for multipass SAR tomography

    NASA Astrophysics Data System (ADS)

    Muirhead, F.; Mulgrew, B.; Woodhouse, I. H.; Greig, D.

    2015-10-01

    Synthetic aperture radar (SAR) systems produce high resolution, two dimensional imaging of areas of environmental interest. SAR interferometry and tomography enables these techniques to extend to three dimensional imaging by exploiting multiple SAR images with diversity in space and time. These techniques require accurate phase information over multiple images as the data is extremely sensitive to deviations from the reference track, therefore to enable interferometry and tomography an accurate autofocus solution is required. This paper investigates phase errors resulting from navigational uncertainties in multipass spotlight SAR imaging and uses techniques from the field of compressive sensing to achieve an autofocus solution. The proposed algorithm builds on previous autofocus work by expanding it to the multipass case and jointly recovers phase errors for all images simultaneously, making it extremely useful for interferometry and tomography techniques. The algorithm described uses pixels that are stable in all SAR images to gain an autofocus solution as these are the pixels that are the focus for analysis using tomography. This is unlike conventional autofocus, which just works on an image-by-image basis. The tools of compressive sensing can be used to concurrently select pixels for bright image elements that are stable and coherent over all images, as these pixels are sparse in the image domain, and calculate the phase errors present in each pass. Using the multipass data after autofocus, height distributions for scatterers in single pixels are determined for simulated forest scenes at X-band. The performance of the autofocus algorithm is examined through numerical simulations and is also applied to real data collected from Selex ES's airborne, X-band, experimental SAR system. The experimental results demonstrate that the algorithm effectively achieves an autofocus solution. By finding the vertical distribution of two scatterers in a single pixel over

  20. Surface deformation of Taipei basin detected by Differential SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Chang, C.; Yen, J.; Lin, M.

    2006-12-01

    Taiwan island is located between the southeastern periphery of the Eurasian plate and the Philippine Sea plate. The two converging plates produced very active tectonics, and can be seen by the high seismicity and deformation rate. Taipei, the highest populated area, center of politics, and economics in Taiwan, is in Taipei basin at the northern part of the island. There are several faults in and surrounding the basin, and the city is threatened with a high geological hazard potential that we should keep monitoring the crustal deformation to prevent and mitigate the disaster effect. The aims of our study is to apply the DInSAR technique to determine the surface deformation of Taipei basin area, and discussing the relation between the manifestation of deformation and the tectonically active region, Shanjiao fault. In the past few years, Differential SAR Interferometry (DInSAR) has been proved to be a powerful technique for monitoring the neotectonic activities and natural hazards. High spatial sampling rate of DInSAR technique allows studies of surface deformations with centimeter accuracy. In this area, we used ERS-1/2 SAR images acquired from 1993 to 2005 to generate 10 differential interferograms and processed the data using DIAPASON developed by CNES and SRTM global DEM.From our results, the deformation rate in Taipei is generally high in the western end of the basin along the Shanjiao fault and decrease eastward, while the subsidence center often appeared in the center of the Taipei basin. The neotectonic activity of the Shanjiao fault appeared to be insignificant by itself but it seemed to separate the subsiding basin from the surrounding areas. Further comparison between our DInSAR results and isopach of the Taipei basin revealed that the subsidence centers appeared in the interferograms did not coincide with the location where the sediments are thickest. Our results from differential interferometry will be compared to other geodetic measurements such as the

  1. Metal adsorption on mosses: Toward a universal adsorption model.

    PubMed

    González, A G; Pokrovsky, O S

    2014-02-01

    This study quantifies the adsorption of heavy metals on 4 typical moss species used for environmental monitoring in the moss bag technique. The adsorption of Cu(2+), Cd(2+), Ni(2+), Pb(2+) and Zn(2+) onto Hypnum sp., Sphagnum sp., Pseudoscleropodium purum and Brachytecium rutabulum has been investigated using a batch reactor in a wide range of pH (1.3-11.0) and metal concentrations in solution (1.6μM-3.8mM). A Linear Programming Model (LPM) was applied for the experimental data to derive equilibrium constants and the number of surface binding sites. The surface acid-base titration performed for 4 mosses at a pH range of 3-10 in 0.1M NaNO3 demonstrated that Sphagnum sp. is the most efficient adsorbent as it has the maximal number of proton-binding sites on the surface (0.65mmol g(-1)). The pKa computed for all the moss species suggested the presence of 5 major functional groups: phosphodiester, carboxyl, phosphoryl, amine and polyphenols. The results of pH-edge experiments demonstrated that B. rutabulum exhibits the highest percentage of metal adsorption and has the highest number of available sites for most of the metals studied. However, according to the results of the constant pH "Langmuirian" isotherm, Sphagnum sp. can be considered as the strongest adsorbent, although the relative difference from other mosses is within 20%. The LPM was found to satisfactorily fit the experimental data in the full range of the studied solution parameters. The results of this study demonstrate a rather similar pattern of five metal adsorptions on mosses, both as a function of pH and as a metal concentration, which is further corroborated by similar values of adsorption constants. Therefore, despite the species and geographic differences between the mosses, a universal adsorption edge and constant pH adsorption isotherm can be recommended for 4 studied mosses. The quantitative comparison of metal adsorption with other common natural organic and inorganic materials demonstrates

  2. GPU-accelerated MRF segmentation algorithm for SAR images

    NASA Astrophysics Data System (ADS)

    Sui, Haigang; Peng, Feifei; Xu, Chuan; Sun, Kaimin; Gong, Jianya

    2012-06-01

    Markov Random Field (MRF) approaches have been widely studied for Synthetic Aperture Radar (SAR) image segmentation, but they have a large computational cost and hence are not widely used in practice. Fortunately parallel algorithms have been documented to enjoy significant speedups when ported to run on a graphics processing units (GPUs) instead of a standard CPU. Presented here is an implementation of graphics processing units in General Purpose Computation (GPGPU) for SAR image segmentation based on the MRF method, using the C-oriented Compute Unified Device Architecture (CUDA) developed by NVIDIA. This experiment with GPGPU shows that the speed of segmentation can be increased by a factor of 10 for large images.

  3. Sandia Airspace Recording System (SARS) software reference manual

    SciTech Connect

    Tenney, J.L.

    1996-04-01

    SARS is a data acquisition system designed to gather and process radar data from aircraft flights. A database of flight trajectories has been developed for Albuquerque, NM, and Amarillo, TX. The data is used for safety analysis and risk assessment reports. To support this database effort, Sandia developed a collection of hardware and software tools to collect and post process the aircraft radar data. This document describes the data reduction tools which comprise the SARS, and maintenance procedures for the hardware and software system.

  4. Marine Targets Classification in PolInSAR Data

    NASA Astrophysics Data System (ADS)

    Chen, Peng; Yang, Jingsong; Ren, Lin

    2014-11-01

    In this paper, marine stationary targets and moving targets are studied by Pol-In-SAR data of Radarsat-2. A new method of stationary targets detection is proposed. The method get the correlation coefficient image of the In-SAR data, and using the histogram of correlation coefficient image. Then, A Constant False Alarm Rate (CFAR) algorithm and The Probabilistic Neural Network model are imported to detect stationary targets. To find the moving targets, Azimuth Ambiguity is show as an important feature. We use the length of azimuth ambiguity to get the target's moving direction and speed. Make further efforts, Targets classification is studied by rebuild the surface elevation of marine targets.

  5. Use of SAR data to study active volcanoes in Alaska

    USGS Publications Warehouse

    Dean, K.G.; Engle, K.; Lu, Zhiming; Eichelberger, J.; Neal, T.; Doukas, M.

    1996-01-01

    Synthetic Aperture Radar (SAR) data of Westdahl, Veniaminof, and Novarupta volcanoes in the Aleutian Arc of Alaska were analyzed to investigate recent surface volcanic processes. These studies support ongoing monitoring and research by the Alaska Volcano Observatory (AVO) in the North Pacific Ocean Region. Landforms and possible crustal deformation before, during, or after eruptions were detected and analyzed using data from the European Remote Sensing Satellites (ERS), Japanese Earth Resources Satellite (JERS) and the U. S. Seasat platforms. Field observations collected by scientists from the AVO were used to verify the results from the analysis of SAR data.

  6. Use of SAR data to study active volcanoes in Alaska

    USGS Publications Warehouse

    Dean, K.G.; Engle, K.; Lu, Zhiming; Eichelberger, J.; Near, T.; Doukas, M.

    1996-01-01

    Synthetic Aperture Radar (SAR) data of the Westdahl, Veniaminof, and Novarupta volcanoes in the Aleutian Arc of Alaska were analysed to investigate recent surface volcanic processes. These studies support ongoing monitoring and research by the Alaska Volcano Observatory (AVO) in the North Pacific Ocean Region. Landforms and possible crustal deformation before, during, or after eruptions were detected and analysed using data from the European Remote Sensing Satellites (ERS), the Japanese Earth Resources Satellite (JERS) and the US Seasat platforms. Field observations collected by scientists from the AVO were used to verify the results from the analysis of SAR data.

  7. Performance evaluation of the JPL interim digital SAR processor

    NASA Technical Reports Server (NTRS)

    Wu, C.; Barkan, B.; Curlander, J.; Jin, M.; Pang, S.

    1983-01-01

    The performance of the Interim Digital SAR Processor (IDP) was evaluated. The IDP processor was originally developed for experimental processing of digital SEASAT SAR data. One phase of the system upgrade which features parallel processing in three peripheral array processors, automated estimation for Doppler parameters, and unsupervised image pixel location determination and registration was executed. The method to compensate for the target range curvature effect was improved. A four point interpolation scheme is implemented to replace the nearest neighbor scheme used in the original IDP. The processor still maintains its fast throughput speed. The current performance and capability of the processing modes now available on the IDP system are updated.

  8. InSAR Scientific Computing Environment - The Home Stretch

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    The Interferometric Synthetic Aperture Radar (InSAR) Scientific Computing Environment (ISCE) is a software development effort in its third and final year within the NASA Advanced Information Systems and Technology program. The ISCE is a new computing environment for geodetic image processing for InSAR sensors enabling scientists to reduce measurements directly from radar satellites to new geophysical products with relative ease. The environment can serve as the core of a centralized processing center to bring Level-0 raw radar data up to Level-3 data products, but is adaptable to alternative processing approaches for science users interested in new and different ways to exploit mission data. Upcoming international SAR missions will deliver data of unprecedented quantity and quality, making possible global-scale studies in climate research, natural hazards, and Earth's ecosystem. The InSAR Scientific Computing Environment has the functionality to become a key element in processing data from NASA's proposed DESDynI mission into higher level data products, supporting a new class of analyses that take advantage of the long time and large spatial scales of these new data. At the core of ISCE is a new set of efficient and accurate InSAR algorithms. These algorithms are placed into an object-oriented, flexible, extensible software package that is informed by modern programming methods, including rigorous componentization of processing codes, abstraction and generalization of data models. The environment is designed to easily allow user contributions, enabling an open source community to extend the framework into the indefinite future. ISCE supports data from nearly all of the available satellite platforms, including ERS, EnviSAT, Radarsat-1, Radarsat-2, ALOS, TerraSAR-X, and Cosmo-SkyMed. The code applies a number of parallelization techniques and sensible approximations for speed. It is configured to work on modern linux-based computers with gcc compilers and python

  9. PolInSAR at Low Frequency and Ionospheric Effects

    NASA Astrophysics Data System (ADS)

    Dubois-Fernandez, P.; Angelliaume, S.; Truong-Loi, M.-L.; Freeman, A.; Pottier, E.

    2009-04-01

    Global warning is now known to be the major environmental issue mankind will have to face in the next decade. Monitoring of vegetation and biomass is clearly an essential piece of information required at all levels ranging from the scientific studies to understand and forecast, to the political actors and government leaders responsible for drafting remediation policies and evaluating their impact. Microwave remote sensing with the low-frequency SAR technique can provide a useful characterization of forest (spatial coverage, species, density, height...) at a global scale, relying on the all-weather imaging capabilities of SAR linked with the significant penetration of the low-frequency EM wave in the canopy. The published techniques for forest characterization from low frequency SAR data include radiometry inversion, polarimetric inversion based on the anisotropy parameters and PolInSAR Random Volume Over Ground inversion [1]. In this paper, we will more specifically concentrate on the PolInSAR technique and the impact of ionospheric effect on this inversion. PolInSAR at low frequency can be envisioned with two radar platforms flying in formation or as a repeat pass mission. The second alternative is more plausible given the cost and the size of a low frequency SAR instrument. However the two cases will be discussed in the paper. Among the challenges, the following questions need to be addressed: · What is the impact of ionosphere and Faraday rotation on the PolInSAR inversion results? · Is it necessary to correct the data prior to applying the inversion and what is the highest Faraday rotation for which a correction is not necessary? · What is the effect of loss of interferometric coherence and could this be compensated for? · Can the technique provide an estimation of the Faraday rotation or the differential Faraday rotation? · How does ionospheric and calibration effects interact? · What are the implications on a compact polarimetry mode of operation?

  10. Knowledge-based segmentation of SAR data with learned priors.

    PubMed

    Haker, S; Sapiro, G; Tannenbaum, A

    2000-01-01

    An approach for the segmentation of still and video synthetic aperture radar (SAR) images is described. A priori knowledge about the objects present in the image, e.g., target, shadow and background terrain, is introduced via Bayes' rule. Posterior probabilities obtained in this way are then anisotropically smoothed, and the image segmentation is obtained via MAP classifications of the smoothed data. When segmenting sequences of images, the smoothed posterior probabilities of past frames are used to learn the prior distributions in the succeeding frame. We show with examples from public data sets that this method provides an efficient and fast technique for addressing the segmentation of SAR data. PMID:18255401

  11. Picture processing of SAR L-band imagery

    NASA Technical Reports Server (NTRS)

    Bryan, M. L.; Stromberg, W. D.; Farr, T.

    1977-01-01

    Data digitization and thresholding are applied to two scenes - sea ice and fresh-water lakes - to define the possible uses of automatic picture processing of uncalibrated SAR L-band imagery. It is shown that certain types of features, those which have constant returns which are also very high or very low in intensity can be effectively studied using simple automatic picture processing techniques applied to uncalibrated radar data. In areas which are generally inaccessible or in which monitoring of the changes of some types of earth surfaces are required, the uncalibrated SAR data can provide valuable inputs for modeling and mapping purposes.

  12. SAR observations of the Gulf Stream during SWADE

    NASA Technical Reports Server (NTRS)

    Vachon, Paris W.; Liu, Antony K.; Mollo-Christensen, Erik

    1992-01-01

    The Surface Wave Dynamics Experiment (SWADE) has gathered SAR observations of the Gulf Stream that show a change in ocean surface brightness; this may be due to the effects of a change in air-sea temperature difference across the observed edge, where the boundary is defined by warm, quickly flowing Gulf Stream water and cooler, relatively stationary shelf water. The two images discussed indicate the possibility of deepening understanding of Gulf Stream front dynamics by using the abundant spatial data of SAR imagery, in conjunction with more conventional (point-like) data on hydrography and currents.

  13. Coherent Target Recognization Based on SAR Sub-Aperture Analysis

    NASA Astrophysics Data System (ADS)

    Gao, Sheng; Zeng, Qiming; Tong, Qingxi; Jiao, Jian

    2014-11-01

    The selection of point-like scatterers, or PS (Persistent Scatterers) is an essential step in PS-InSAR processing. And the accuracy of measured deformation can be severely influenced by the density of PSs. The usually used methods are based on time series analysis of the amplitude or phase of the targets, needing a large number of SAR images. Here an alternate method using only one SLC is introduced, which exploits the different behaviours of PS and DS (Distributed Scatterers) in different sub-aperture images.

  14. Software For Tie-Point Registration Of SAR Data

    NASA Technical Reports Server (NTRS)

    Rignot, Eric; Dubois, Pascale; Okonek, Sharon; Van Zyl, Jacob; Burnette, Fred; Borgeaud, Maurice

    1995-01-01

    SAR-REG software package registers synthetic-aperture-radar (SAR) image data to common reference frame based on manual tie-pointing. Image data can be in binary, integer, floating-point, or AIRSAR compressed format. For example, with map of soil characteristics, vegetation map, digital elevation map, or SPOT multispectral image, as long as user can generate binary image to be used by tie-pointing routine and data are available in one of the previously mentioned formats. Written in FORTRAN 77.

  15. Acousto-optic techniques for real SAR imaging

    NASA Technical Reports Server (NTRS)

    Haney, M.; Psaltis, D.

    1985-01-01

    Recent advancements in the development of the Real Time Acousto-optic SAR Processor are presented. In particular, the technique for introducing the azimuth reference function into the processor via an acousto-optic Bragg cell is discussed. This approach permits the reference function to be stored in electronic memory, thus giving the processor the flexibility needed to adapt rapidly to changes in the radar/target geometry. The architecture is described and results are presented which show the applicability of the technique to both spot-light and strip-map SAR.

  16. Lithologic mapping in a sedimentary environment using multipolarization SAR images

    NASA Technical Reports Server (NTRS)

    Evans, D. L.; Schenck, L. R.

    1985-01-01

    Multipolarization Synthetic Aperture Radar (SAR) data from the NASA/JPL aircraft SAR were used in conjunction with LANDSAT Thematic Mapper (TM), Thermal Infrared Multispectral Scanner (TIMS), and Airborne Imaging Spectrometer (AIS) data as part of a three-year research program to evaluate the utility of remote sensing measurements for analysis of sedimentary basins. The purpose of this research effort is to construct stratigraphic columns, map variations in the lithology, geometry, and structure of sedimentary rocks in the Wind River/Bighorn Basin area, Wyoming, and to integrate remote sensing data with conventional rain models of basin formation and evolution.

  17. Fundamental SAR ATR performance predictions for design trade-offs

    NASA Astrophysics Data System (ADS)

    Horowitz, Larry L.; Brendel, Gary F.

    1997-07-01

    This paper discusses work toward a fundamental, algorithm- independent view of the ATR performance that can be achieved using SAR data. Such ATR performance predictions are intended to enable evaluation of performance tradeoffs for SAR designs, including both parameter selections and added domains of SAR observation, such as 3D, full polarimetry, multiaspect and/or multifrequency. In the paper we evaluate the classification error for two tactical targets using a Monte Carlo technique. A number of approximations are made and are detailed in the paper. Data on target signatures come from pencil-beam laser data and target photographs, which determine shadowing of the ground clutter. A single aspect angle is used for each target in the initial results. A layer of radar netting is modeled on both targets. This information is used as 'ground truth', to compute the average power that would be seen in each pixel of a SAR image, for each target. SAR image trials are then generated using independent Rayleigh amplitude fades in each pixel. In an optimal Bayesian fashion, the smaller of the probabilities of target (T1) or T2 given the trial image data is the error probability for that trial. An average over the Monte Carlo image trials yields the overall classification error probability. Comments are given on reducing the number of required trials in such a Monte Carlo. THree results of the work are shown. First, a tradeoff is made of ATR performance versus SAR resolution. ATR improves as the resolution is made finer, and physical reasons for this are discussed. Second, the relative ATR utility is determined for those pixels where at least one target has scatterer as compared with those pixels where the targets differ only in the degree to which they shadow the ground clutter. Third, an early analytical result is given for interferometric SAR, showing the physical reason behind the potential of height-sensing SAR to improve ATR - the possibility of canceling the background

  18. Fractional Statistical Theory of Adsorption of Polyatomics

    NASA Astrophysics Data System (ADS)

    Riccardo, J. L.; Ramirez-Pastor, A. J.; Romá, F.

    2004-10-01

    A new theoretical description of fractional statistical theory of adsorption (FSTA) phenomena is presented based on Haldane’s statistics. Thermodynamic functions for adsorption of polyatomics are analytically developed. The entropy is characterized by an exclusion parameter g, which relates to the configuration of the admolecules and surface geometry. FSTA provides a simple framework to address a large class of complex adsorption systems. Comparisons of theoretical adsorption isotherms with experiments and simulations indicate that adsorption configuration and adsorption energy can accurately be assessed from this theory.

  19. Fractional statistical theory of adsorption of polyatomics.

    PubMed

    Riccardo, J L; Ramirez-Pastor, A J; Romá, F

    2004-10-29

    A new theoretical description of fractional statistical theory of adsorption (FSTA) phenomena is presented based on Haldane's statistics. Thermodynamic functions for adsorption of polyatomics are analytically developed. The entropy is characterized by an exclusion parameter g, which relates to the configuration of the admolecules and surface geometry. FSTA provides a simple framework to address a large class of complex adsorption systems. Comparisons of theoretical adsorption isotherms with experiments and simulations indicate that adsorption configuration and adsorption energy can accurately be assessed from this theory. PMID:15525184

  20. Effects of reactor decontamination complexing agents on soil adsorption-column studies

    SciTech Connect

    Serne, R. Jeffrey; Lindenmeier, Clark W.; Cantrell, Kirk J.; Owen, Antionette T.

    1999-12-01

    The effects of picolinate, an organic ligand used to decontaminate nuclear reactor cooling systems, in leachates generated from shallow-land burial (SLB) of low-level nuclear wastes (LLW) on soil adsorption was determined. Using batch adsorption tests and varying the concentration of picolinate, the adsorption tendencies of two metals [Ni(II) and U(VI)] and the ligand were measured as a function of solution pH. We found that when total metal concentrations were fixed at 10^-5 M, picolinate at ligand-to-metal [L:M] ratios $10 did significantly reduce adsorption of Ni but even at a L:M ratio of 100 there was no effect on U(VI) adsorption. These results are compared with data on other metals in the presence of picolinate and for metal adsorption in the presence of EDTA. We conclude that picolinic acid is less of a threat than EDTA in waste leachates to reduce metal adsorption (increase mobility) and that picolinate concentrations must reach or exceed 10^-4 M for the most impacted metals (i.e., those that form the very strongest complexes with picolinate). There are no leachate data on these decontamination agents for the common burial technique (disposal of de-watered resins in high integrity containers) that can be used to evaluate potential hazards of these organo-radionuclide complexes.