Science.gov

Sample records for active microwave sensing

  1. Microwave remote sensing: Active and passive. Volume 1 - Microwave remote sensing fundamentals and radiometry

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Moore, R. K.; Fung, A. K.

    1981-01-01

    The three components of microwave remote sensing (sensor-scene interaction, sensor design, and measurement techniques), and the applications to geoscience are examined. The history of active and passive microwave sensing is reviewed, along with fundamental principles of electromagnetic wave propagation, antennas, and microwave interaction with atmospheric constituents. Radiometric concepts are reviewed, particularly for measurement problems for atmospheric and terrestrial sources of natural radiation. Particular attention is given to the emission by atmospheric gases, clouds, and rain as described by the radiative transfer function. Finally, the operation and performance characteristics of radiometer receivers are discussed, particularly for measurement precision, calibration techniques, and imaging considerations.

  2. Active microwave remote sensing of oceans, chapter 3

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A rationale is developed for the use of active microwave sensing in future aerospace applications programs for the remote sensing of the world's oceans, lakes, and polar regions. Summaries pertaining to applications, local phenomena, and large-scale phenomena are given along with a discussion of orbital errors.

  3. Technology advances in active and passive microwave sensing through 1985

    NASA Technical Reports Server (NTRS)

    Barath, F. T.

    1977-01-01

    As a result of a growing awareness by the remote sensing community of the unique capabilities of passive and active microwave sensors, these instruments are expected to grow in the next decade in numbers, versatility and complexity. The Nimbus-G and Seasat-A Scanning Multichannel Microwave Spectrometer (SMMR), the Seasat-A radar altimeter, scatterometer and synthetic aperture radar represent the first systematic attempt at exploring a wide variety of applications utilizing microwave sensing techniques and are indicators of the directions in which the pertinent technology is likely to evolve. The trend is toward high resolution multi-frequency imagers spanning wide frequency ranges and wide swaths requiring sophisticated receivers, real-time data processors and most importantly, complex antennas.

  4. Active microwave remote sensing of earth/land, chapter 2

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Geoscience applications of active microwave remote sensing systems are examined. Major application areas for the system include: (1) exploration of petroleum, mineral, and ground water resources, (2) mapping surface and structural features, (3) terrain analysis, both morphometric and genetic, (4) application in civil works, and (5) application in the areas of earthquake prediction and crustal movements. Although the success of radar surveys has not been widely publicized, they have been used as a prime reconnaissance data base for mineral exploration and land-use evaluation in areas where photography cannot be obtained.

  5. Active-Passive Microwave Remote Sensing of Martian Permafrost and Subsurface Water

    NASA Technical Reports Server (NTRS)

    Raizer, V.; Linkin, V. M.; Ozorovich, Y. R.; Smythe, W. D.; Zoubkov, B.; Babkin, F.

    2000-01-01

    The investigation of permafrost formation global distribution and their appearance in h less than or equal 1 m thick subsurface layer would be investigated successfully by employment of active-passive microwave remote sensing techniques.

  6. Active Microwave Remote Sensing Observations of Weddell Sea Ice

    NASA Technical Reports Server (NTRS)

    Drinkwater, Mark R.

    1997-01-01

    Since July 1991, the European Space Agency's ERS-1 and ERS-2 satellites have acquired radar data of the Weddell Sea, Antarctica. The Active Microwave Instrument on board ERS has two modes; SAR and Scatterometer. Two receiving stations enable direct downlink and recording of high bit-rate, high resolution SAR image data of this region. When not in an imaging mode, when direct SAR downlink is not possible, or when a receiving station is inoperable, the latter mode allows normalized radar cross-section data to be acquired. These low bit-rate ERS scatterometer data are tape recorded, downlinked and processed off-line. Recent advances in image generation from Scatterometer backscatter measurements enable complementary medium-scale resolution images to be made during periods when SAR images cannot be acquired. Together, these combined C-band microwave image data have for the first time enabled uninterrupted night and day coverage of the Weddell Sea region at both high (25 m) and medium-scale (-20 km) resolutions. C-band ERS-1 radar data are analyzed in conjunction with field data from two simultaneous field experiments in 1992. Satellite radar signature data are compared with shipborne radar data to extract a regional and seasonal signature database for recognition of ice types in the images. Performance of automated sea-ice tracking algorithms is tested on Antarctic data to evaluate their success. Examples demonstrate that both winter and summer ice can be effectively tracked. The kinematics of the main ice zones within the Weddell Sea are illustrated, together with the complementary time-dependencies in their radar signatures. Time-series of satellite images are used to illustrate the development of the Weddell Sea ice cover from its austral summer minimum (February) to its winter maximum (September). The combination of time-dependent microwave signatures and ice dynamics tracking enable various drift regimes to be defined which relate closely to the circulation of the

  7. Microwave sensing from orbit

    NASA Technical Reports Server (NTRS)

    Kritikos, H. N.; Shiue, J.

    1979-01-01

    Microwave sensors, used in conjunction with the traditional sensors of visible and infrared light to extend present capabilities of global weather forecasts and local storm watches, are discussed. The great advantage of these sensors is that they can penetrate or 'see' through cloud formations to monitor temperature, humidity and wind fields below the clouds. Other uses are that they can penetrate the earth deeper than optical and IR systems; they can control their own angle of incidence; they can detect oil spills; and they can enhance the studies of the upper atmosphere through measurement of temperature, water vapor and other gaseous species. Two types of microwave sensors, active and passive, are examined. Special attention is given to the study of the microwave radiometer and the corresponding temperature resolution as detected by the antenna. It is determined that not only will the microwave remote sensors save lives by allowing close monitoring of developing storms, but also save approximately $172 million/year.

  8. Intercomparisons between passive and active microwave remote sensing, and hydrological modeling for soil moisture

    NASA Technical Reports Server (NTRS)

    Wood, E. F.; Lin, D.-S.; Mancini, M.; Thongs, D.; Troch, P. A.; Jackson, T. J.; Famiglietti, J. S.; Engman, E. T.

    1993-01-01

    Soil moisture estimations from a distributed hydrological model and two microwave sensors were compared with ground measurements collected during the MAC-HYDRO'90 experiment. The comparison was done with the purpose of evaluating the performance of the hydrological model and examining the limitations of remote sensing techniques used in soil moisture estimation. An image integration technique was used to integrate and analyze rainfall, soil properties, land cover, topography, and remote sensing imagery. Results indicate that the hydrological model and microwave sensors successfully picked up temporal variations of soil moisture and that the spatial soil moisture pattern may be remotely sensed with reasonable accuracy using existing algorithms.

  9. ESA activities in the use of microwaves for the remote sensing of the Earth

    NASA Technical Reports Server (NTRS)

    Maccoll, D.

    1984-01-01

    The program of activities under way in the European Space Agency (ESA) directed towards Remote Sensing of the oceans and troposphere is discussed. The initial project is the launch of a satellite named ERS-1 with a primary payload of microwave values in theee C- and Ku-bands. This payload is discussed in depth. The secondary payload includes precision location experiments and an instrument to measure sea surface temperature, which are described. The important topic of calibration is extensively discussed, and a review of activities directed towards improvements to the instruments for future satellites is presented. Some discussion of the impact of the instrument payload on the spacecraft design follows and the commitment of ESA to the provision of a service of value to the ultimate user is emphasized.

  10. Intercomparisons between passive and active microwave remote sensing, and hydrological modeling for soil moisture

    NASA Astrophysics Data System (ADS)

    Wood, E. F.; Lin, D.-S.; Mancini, M.; Thongs, D.; Troch, P. A.; Jackson, T. J.; Famiglietti, J. S.; Engman, E. T.

    1993-05-01

    Soil moisture estimates from a distributed hydrological model and two microwave remote sensors (Push Broom Microwave Radiometer and Synthetic Aperture Radar) were compared with the ground measurements collected during the MAC-HYDRO'90 experiment over a 7.4-km2 watershed in central Pennsylvania. Various information, including rainfall, soil properties, land cover, topography and remote sensing imagery, were integrated and analyzed using an image integration technique. It is found that the hydrological model and both microwave sensors successfully pick up the temporal variation of soil moisture. Results also indicate the spatial soil moisture pattern can be remotely sensed within reasonable accuracy using existing algorithms. Watershed averaged soil moisture estimates from the hydrological model are wetter than remotely sensed data. It is difficult to conclude which instrument yield better performance for the studied case. The choice will be based on the intended applications and information that is available.

  11. Towards a Soil Moisture Climate Record from Active and Passive Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Scipal, K.; de Jeu, R.; Dorigo, W.; Su, B.

    2009-04-01

    The latest IPCC assessment report identified soil moisture as an emerging essential climate variable and stressed the need to fosters activities to "assemble, quality check reprocess, and re-analyse" respective datasets "relevant to decadal prediction" Satellite remote sensing can be a powerful data source to fulfil those needs. Unfortunately, methodological problems, lack of validation and limitations in computing have frequently delayed the research process to retrieve soil moisture from space observations. But research in these fields evolved, resulting in several global soil moisture datasets. Today validated global soil moisture data sets are publicly available from active (ERS-1/2, METOP) and passive (SMMR, SSM/I, TMI, AMSR-E) microwave remote sensing instruments. These data sets reach back for more than 30 years. In addition, in the near future dedicated soil moisture sensors such as the SMOS mission will provide experimental soil moisture products in an unprecedented quality. The available data sets are based on different sensors and retrieval concepts. It is now the time to harmonize these different sets to create one long term consistent global soil moisture dataset. Within the ESA project WACMOS (Water Cycle Multi-mission Observation Strategy) respective activities are reinforced. More specifically the objective of the WACMOS soil moisture observatory is to establish a solid scientific basis for the development of long-term coherent soil moisture products. To this end we exploit the triple collocation error estimation technique to assess the error and systematic biases between the different data sets and use a cumulative distribution function matching approach to harmonise the observations. The proposed methodology has the advantage that it can easily be adapted to a new observation record such as observations of the SMOS mission. In this paper we will present first results based on data records from the ERS-1/2 and the AMSR-E missions. We will discuss

  12. Microwave remote sensing laboratory design

    NASA Technical Reports Server (NTRS)

    Friedman, E.

    1979-01-01

    Application of active and passive microwave remote sensing to the study of ocean pollution is discussed. Previous research efforts, both in the field and in the laboratory were surveyed to derive guidance for the design of a laboratory program of research. The essential issues include: choice of radar or radiometry as the observational technique; choice of laboratory or field as the research site; choice of operating frequency; tank sizes and material; techniques for wave generation and appropriate wavelength spectrum; methods for controlling and disposing of pollutants used in the research; and pollutants other than oil which could or should be studied.

  13. NORSEX 1979 microwave remote sensing data report

    NASA Technical Reports Server (NTRS)

    Hennigar, H. F.; Schaffner, S. K.

    1982-01-01

    Airborne microwave remote sensing measurements obtained by NASA Langley Research Center in support of the 1979 Norwegian Remote Sensing Experiment (NORSEX) are summarized. The objectives of NORSEX were to investigate the capabilities of an active/passive microwave system to measure ice concentration and type in the vicinity of the marginal ice zone near Svalbard, Norway and to apply microwave techniques to the investigation of a thermal oceanic front near Bear Island, Norway. The instruments used during NORSEX include the stepped frequency microwave radiometer, airborne microwave scatterometer, precision radiation thermometer and metric aerial photography. The data are inventoried, summarized, and presented in a user-friendly format. Data summaries are presented as time-history plots which indicate when and where data were obtained as well as the sensor configuration. All data are available on nine-track computer tapes in card-image format upon request to the NASA Langley Technical Library.

  14. Passive Microwave Remote Sensing of Soil Moisture

    NASA Technical Reports Server (NTRS)

    Njoku, Eni G.; Entekhabi, Dara

    1994-01-01

    Microwave remote sensing provides a unique capability for direct observation of soil moisture... This Paper outlines the basic principles of the passive microwave technique for soil moisture sensing, and reviews briefly the status of current retrieval methods.

  15. Passive and Active Microwave Remote Sensing of Precipitation and Latent Heating Distributions in the Tropics from TRMM

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Kummerow, Christian D.; Yang, Song; Haddad, Ziad S.; Tao, Wei-Kuo; Wang, Yansen; Lang, Stephen E.; Braun, Scott A.; Chiu, Christine; Wang, Jian-Jian

    2002-01-01

    Passive and active microwave remote sensing data are analyzed to identify signatures of precipitation and vertical motion in tropical convection. A database of cloud/radiative model simulations is used to quantify surface rain rates and latent heating profiles that are consistent with these signatures. At satellite footprint-scale (approximately 10 km), rain rate and latent heating estimates are subject to significant random errors, but by averaging the estimates in space and time, random errors are substantially reduced, Bias errors have been minimized by improving the microphysics in the supporting cloud/radiative model simulations, and by imposing a consistent definition of remotely-sensed and model-simulated convective/stratiform rain coverage. Remotely-sensed precipitation and latent heating distributions in the tropics are derived from Tropical Rainfall Measuring Mission (TRMM) and Special Sensor Microwave/ Imager (SSM/ I) sensor data. The prototype Version 6 TRMM passive microwave algorithm typically yields average heating profiles with maxima between 6 and 7 km altitude for organized mesoscale convective systems. Retrieved heating profiles for individual convective systems are compared to coincident estimates based upon a combination of dual-Doppler radar and rawinsonde data. Also, large-scale latent heating distributions are compared to estimates derived from a simpler technique that utilizes observations of surface rain rate and stratiform rain proportion to infer vertical heating structure. Results of these tests will be presented at the conference.

  16. New concepts for microwave sensing

    NASA Astrophysics Data System (ADS)

    Bolomey, Jean-Charles

    1994-09-01

    For a long time, microwaves have been considered as a possible sensing agent for nondestructive testing/evaluation purposes. This trend has still been reinforced these last years with the advent of new microwave penetrable materials, such as composites. Inspection of materials via a mechanically scanned probe has proven to offer a convenient, but time consuming, way to measure local reflexion or transmission coefficients and, hence, to evaluate defects, faults, etc... High speed measurements are now possible by using arrays of fixed probes, resulting in attractive imaging equipments. Indeed, the availability of amplitude/phase data allows us to consider different processing techniques, the complexity of which can be selected according to the required performances in terms of contrast, spatial and time resolutions. This paper reviews some of the most promising approaches, such as non-linear inverse scattering techniques and neural networks. Prospective considerations are devoted to the future of such sophisticated microwave sensing techniques.

  17. Microwave backscattering theory and active remote sensing of the ocean surface

    NASA Technical Reports Server (NTRS)

    Brown, G. S.; Miller, L. S.

    1977-01-01

    The status is reviewed of electromagnetic scattering theory relative to the interpretation of microwave remote sensing data acquired from spaceborne platforms over the ocean surface. Particular emphasis is given to the assumptions which are either implicit or explicit in the theory. The multiple scale scattering theory developed during this investigation is extended to non-Gaussian surface statistics. It is shown that the important statistic for the case is the probability density function of the small scale heights conditioned on the large scale slopes; this dependence may explain the anisotropic scattering measurements recently obtained with the AAFE Radscat. It is noted that present surface measurements are inadequate to verify or reject the existing scattering theories. Surface measurements are recommended for qualifying sensor data from radar altimeters and scatterometers. Additional scattering investigations are suggested for imaging type radars employing synthetically generated apertures.

  18. Microwave remote sensing from space for earth resource surveys

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The concepts of radar remote sensing and microwave radiometry are discussed and their utility in earth resource sensing is examined. The direct relationship between the character of the remotely sensed data and the level of decision making for which the data are appropriate is considered. Applications of active and a passive microwave sensing covered include hydrology, land use, mapping, vegetation classification, environmental monitoring, coastal features and processes, geology, and ice and snow. Approved and proposed microwave sensors are described and the use of space shuttle as a development platform is evaluated.

  19. Microwave remote sensing of snowpack properties

    NASA Technical Reports Server (NTRS)

    Rango, A. (Editor)

    1980-01-01

    Topic concerning remote sensing capabilities for providing reliable snow cover data and measurement of snow water equivalents are discussed. Specific remote sensing technqiues discussed include those in the microwave region of the electromagnetic spectrum.

  20. Soil moisture sensing with microwave techniques

    NASA Technical Reports Server (NTRS)

    Schmugge, T.

    1980-01-01

    Microwave approaches for the remote sensing of soil moisture are discussed, with the advantages described as follows: (1) the all-weather capability, (2) the greater penetration depth into the soil and through vegetation than with optical or infrared sensors, and (3) the large changes in the dielectric properties of soil produced by changes in water content. Both active and passive microwave approaches are discussed. The dependence of the relationship between microwave response and soil moisture on such things as soil texture, surface roughness, vegetative cover and nonuniform moisture and temperature profiles is analyzed from both the experimental and theoretical viewpoints. The dielectric properties of the soil are analyzed quantitatively, as these control the reflective and emissive properties of the soil surface, and a model for estimating a soil's dielectric properties from its texture and moisture content is also presented. Emissivity is calculated using the Fresnel equation of electromagnetic theory, and reflectivity is shown to be decreased by surface roughness, while the backscatter coefficient increases. It is demonstrated, that microwave radiometers are sensitive to soil moisture for a wide range of surface conditions, and that the longer wavelengths are best for soil moisture sensing.

  1. Soil Moisture Retrieval Through Changing Corn Using Active/Passive Microwave Remote Sensing

    NASA Technical Reports Server (NTRS)

    ONeill, P. E.; Joseph, A.; DeLannoy, G.; Lang, R.; Utku, C.; Kim, E.; Houser, P.; Gish, T.

    2003-01-01

    An extensive field experiment was conducted from May-early October, 2002 at the heavily instrumented USDA-ARS (U.S. Dept. of Agriculture-Agricultural Research Service) OPE3 (Optimizing Production Inputs for Economic and Environmental Enhancement) test site in Beltsville, MD to acquire data needed to address active/passive microwave algorithm, modeling, and ground validation issues for accurate soil moisture retrieval. During the experiment, a tower-mounted 1.4 GHz radiometer (Lrad) and a truck-mounted dual-frequency (1.6 and 4.75 GHz) radar system were deployed on the northern edge of the site. The soil in this portion of the field is a sandy loam (silt 23.5%, sand 60.3%, clay 16.1%) with a measured bulk density of 1.253 g/cu cm. Vegetation cover in the experiment consisted of a corn crop which was measured from just after planting on April 17, 2002 through senescence and harvesting on October 2. Although drought conditions prevailed during the summer, the corn yield was near average, with peak biomass reached in late July.

  2. Derivation of soil moisture sensing depth from microwave satellite sensors

    NASA Astrophysics Data System (ADS)

    de Jeu, Richard; Holmes, Thomas

    2015-04-01

    Soil moisture retrievals from low frequency passive microwave satellite sensors (e.g. ESAs current Soil Moisture Ocean Salinity mission (SMOS)) are assumed to estimate spatially explicit soil moisture content of the first centimeters. However, the exact microwave sensing depth and the dynamic nature of the sensing depth at satellite grid scale is still to a large degree unknown. A more reliable estimation of the sensing depth would greatly improve the utility of microwave soil moisture retrievals. Validation activities could be fine-tuned, algorithms could be improved, and modeling applications could match observations to more optimal model depth. In addition to all this, soil moisture sensing depth information is essential for the development of a consistent fundamental soil moisture climate data record. With the availability of multiple polar orbiting satellites with multi-frequency microwave radiometers it has now become possible to study the microwave sensing depth as it manifests itself at observational scales. The approach uses the differences in timing between the diurnal temperature cycle (DTC) of microwave observations and thermal infrared observations as a basis to calculate the sensing depth. Using an intercalibrated multi sensor microwave data set and geostationary thermal infrared observations this approach is used to evaluate sensing depth at several microwave frequencies relevant for soil moisture retrieval. Field data in combination with an integrated thermodynamic hydrological microwave model are then used to develop guidelines for a dynamic sensing depth algorithm. The key advantage of this approach is its global applicability, providing timely and consistent information on sensing depth for different satellite soil moisture datasets.

  3. Microwave remote sensing of snowpacks

    NASA Technical Reports Server (NTRS)

    Stiles, W. H.; Ulaby, F. T.

    1980-01-01

    The interaction mechanisms responsible for the microwave backscattering and emission behavior of snow were investigated, and models were developed relating the backscattering coefficient (sigma) and apparent temperature (T) to the physical parameters of the snowpack. The microwave responses to snow wetness, snow water equivalent, snow surface roughness, and to diurnal variations were investigated. Snow wetness was shown to have an increasing effect with increasing frequency and angle of incidence for both active and passive cases. Increasing snow wetness was observed to decrease the magnitude sigma and increase T. Snow water equivalent was also observed to exhibit a significant influence sigma and T. Snow surface configuration (roughness) was observed to be significant only for wet snow surface conditions. Diurnal variations were as large as 15 dB for sigma at 35 GHz and 120 K for T at 37 GHz. Simple models for sigma and T of a snowpack scene were developed in terms of the most significant ground-truth parameters. The coefficients for these models were then evaluated; the fits to the sigma and T measurements were generally good. Finally, areas of needed additional observations were outlined and experiments were specified to further the understanding of the microwave-snowpack interaction mechanisms.

  4. Microwave remote sensing of soil moisture

    NASA Technical Reports Server (NTRS)

    Shiue, J. C.; Wang, J. R.

    1988-01-01

    Knowledge of soil moisture is important to many disciplines, such as agriculture, hydrology, and meteorology. Soil moisture distribution of vast regions can be measured efficiently only with remote sensing techniques from airborne or satellite platforms. At low microwave frequencies, water has a much larger dielectric constant than dry soil. This difference manifests itself in surface emissivity (or reflectivity) change between dry and wet soils, and can be measured by a microwave radiometer or radar. The Microwave Sensors and Data Communications Branch is developing microwave remote sensing techniques using both radar and radiometry, but primarily with microwave radiometry. The efforts in these areas range from developing algorithms for data interpretation to conducting feasibility studies for space systems, with a primary goal of developing a microwave radiometer for soil moisture measurement from satellites, such as EOS or the Space Station. These efforts are listed.

  5. Recent glacier surface snowpack melt in Novaya Zemlya and Severnaya Zemlya derived from active and passive microwave remote sensing data

    NASA Astrophysics Data System (ADS)

    Zhao, Meng

    The warming rate in the Russian High Arctic (RHA) (36˜158°E, 73˜82°N) is outpacing the pan-Arctic average, and its effect on the small glaciers across this region needs further examination. The temporal variation and spatial distribution of surface melt onset date (MOD) and total melt days (TMD) throughout the Novaya Zemlya (NovZ) and Severnaya Zemlya (SevZ) archipelagoes serve as good indicators of ice mass ablation and glacier response to regional climate change in the RHA. However, due to the harsh environment, long-term glaciological observations are limited, necessitating the application of remotely sensed data to study the surface melt dynamics. The high sensitivity to liquid water and the ability to work without solar illumination and penetrate non-precipitating clouds make microwave remote sensing an ideal tool to detect melt in this region. This work extracts resolution-enhanced passive and active microwave data from different periods and retrieves a decadal melt record for NovZ and SevZ. The high correlation among passive and active data sets instills confidence in the results. The mean MOD is June 20th on SevZ and June 10th on NovZ during the period of 1992-2012. The average TMDs are 47 and 67 days on SevZ and NovZ from 1995 to 2011, respectively. NovZ had large interannual variability in the MOD, but its TMD generally increased. SevZ MOD is found to be positively correlated to local June reanalysis air temperature at 850hPa geopotential height and occurs significantly earlier (˜0.73 days/year, p-value < 0.01) from 1992 to 2011. SevZ also experienced a longer TMD trend (˜0.75 days/year, p-value < 0.05) from 1995 to 2011. Annual mean TMD on both islands are positively correlated with regional summer mean reanalysis air temperature and negatively correlated to local sea ice extent. These strong correlations might suggest that the Russian High Arctic glaciers are vulnerable to the continuously diminishing sea ice extent, the associated air temperature

  6. Microwave remote sensing of soil water content

    NASA Technical Reports Server (NTRS)

    Cihlar, J.; Ulaby, F. T.

    1975-01-01

    Microwave remote sensing of soils to determine water content was considered. A layered water balance model was developed for determining soil water content in the upper zone (top 30 cm), while soil moisture at greater depths and near the surface during the diurnal cycle was studied using experimental measurements. Soil temperature was investigated by means of a simulation model. Based on both models, moisture and temperature profiles of a hypothetical soil were generated and used to compute microwave soil parameters for a clear summer day. The results suggest that, (1) soil moisture in the upper zone can be predicted on a daily basis for 1 cm depth increments, (2) soil temperature presents no problem if surface temperature can be measured with infrared radiometers, and (3) the microwave response of a bare soil is determined primarily by the moisture at and near the surface. An algorithm is proposed for monitoring large areas which combines the water balance and microwave methods.

  7. Passive Microwave Remote Sensing of Soil Moisture

    NASA Technical Reports Server (NTRS)

    Njoku, Eni G.; Entekhabi, Dara

    1996-01-01

    Microwave remote sensing provides a unique capability for direct observation of soil moisture. Remote measurements from space afford the possibility of obtaining frequent, global sampling of soil moisture over a large fraction of the Earth's land surface. Microwave measurements have the benefit of being largely unaffected by cloud cover and variable surface solar illumination, but accurate soil moisture estimates are limited to regions that have either bare soil or low to moderate amounts of vegetation cover. A particular advantage of passive microwave sensors is that in the absence of significant vegetation cover soil moisture is the dominant effect on the received signal. The spatial resolutions of passive Microwave soil moisture sensors currently considered for space operation are in the range 10-20 km. The most useful frequency range for soil moisture sensing is 1-5 GHz. System design considerations include optimum choice of frequencies, polarizations, and scanning configurations, based on trade-offs between requirements for high vegetation penetration capability, freedom from electromagnetic interference, manageable antenna size and complexity, and the requirement that a sufficient number of information channels be available to correct for perturbing geophysical effects. This paper outlines the basic principles of the passive microwave technique for soil moisture sensing, and reviews briefly the status of current retrieval methods. Particularly promising are methods for optimally assimilating passive microwave data into hydrologic models. Further studies are needed to investigate the effects on microwave observations of within-footprint spatial heterogeneity of vegetation cover and subsurface soil characteristics, and to assess the limitations imposed by heterogeneity on the retrievability of large-scale soil moisture information from remote observations.

  8. Sensing vegetation growth and senescence with reflected GPS signals: Active microwave detection of western North America phenology

    NASA Astrophysics Data System (ADS)

    Evans, Sarah Grace

    We explore a new technique to estimate vegetation growth and senescence using reflected GPS signals (multipath) measured by geodetic-quality GPS stations. The operational GPS-IR statistic Normalized Microwave Reflection Index (NMRI), a measure of multipath scattering, exhibits a clear seasonal cycle as is expected for vegetation growth and senescence. The sensing footprint is ˜1000 m 2, larger than that provided by typical in situ observations but smaller than that from space-based products. Since GPS satellites transmit L-band signals, the vegetation estimates derived from GPS reflections provide global phenology monitoring that is sensitive to changes in vegetation canopy water content and biomass. However, GPS reflections are insensitive to plant greenness, clouds, atmosphere, and solar illumination constraints that adversely affect optical-infrared remote sensing vegetation indices like Normalized Difference Vegetation Index (NDVI). Temporal and spatial diffuse scattering of microwave GPS-IR index NMRI and MODIS-based NDVI is documented at both the site-by-site and regional scale at 184 sites over the western United States. We derive NMRI and NDVI range, correlation between NMRI and NDVI signals, and phenology parameters including: start of season, season length, and peak day of year of vegetation growth. These phenology indexes are compared over a five water-year time series (2008 to 2012) to gauge spatial and temporal offsets. Average correlations (R 2=0.527) were found with NMRI variations lagging NDVI by approximately 21 days. This is consistent with the idea that greenup precedes plant growth. Phenology metrics extracted by microwave NMRI record a later start of season, later peak day of year, and shorter season length than determined by optical NDVI. Metrics are offset spatially with the largest offsets along Pacific Ocean coastline, decreasing inland and subdivided by region, supporting that plant growth cycles are controlled by regional climates. This

  9. Microwave remote sensing of ionized air.

    SciTech Connect

    Liao, S.; Gopalsami, N.; Heifetz, A.; Elmer, T.; Fiflis, P.; Koehl, E. R.; Chien, H. T.; Raptis, A. C.

    2011-07-01

    We present observations of microwave scattering from ambient room air ionized with a negative ion generator. The frequency dependence of the radar cross section of ionized air was measured from 26.5 to 40 GHz (Ka-band) in a bistatic mode with an Agilent PNA-X series (model N5245A) vector network analyzer. A detailed calibration scheme is provided to minimize the effect of the stray background field and system frequency response on the target reflection. The feasibility of detecting the microwave reflection from ionized air portends many potential applications such as remote sensing of atmospheric ionization and remote detection of radioactive ionization of air.

  10. Improved microwave radiometry for remote sensing

    NASA Technical Reports Server (NTRS)

    Leber, A.; Flattau, T.

    1979-01-01

    Significant improvements in the gain stability and overall performance of microwave radiometers have been achieved with the use of a self-balancing gain modulation technique. This technique, in combination with automatic thermal calibration, is particularly well suited for remote sensing radiometric applications. The essential features of such a radiometer, including typical data obtained from a spaceborne satellite, is presented to show the instrument's utility.

  11. Microwave Remote Sensing of Soil Moisture

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.

    1985-01-01

    Because of the large contrast between the dielectric constant of liquid water and that of dry soil at microwave wavelength, there is a strong dependence of the thermal emission and radar backscatter from the soil on its moisture content. This dependence provides a means for the remote sensing of the moisture content in a surface layer approximately 5 cm thick. The feasibility of these techniques is demonstrated from field, aircraft and spacecraft platforms. The soil texture, surface roughness, and vegetative cover affect the sensitivity of the microwave response to moisture variations with vegetation being the most important. It serves as an attenuating layer which can totally obscure the surface. Research indicates that it is possible to obtain five or more levels of moisture discrimination and that a mature corn crop is the limiting vegetation situation.

  12. Microwave sensing of tree trunks

    NASA Astrophysics Data System (ADS)

    Jezova, Jana; Mertens, Laurence; Lambot, Sebastien

    2015-04-01

    was divided into three sections to separate parts with different moisture (heartwood and sapwood) or empty space (decays). For easier manipulation with the antenna we developed a special ruler for measuring the distance along the scans. Instead of the surveying wheel we read the distance with a camera, which was fixed on the antenna and focused on the ruler with a binary pattern. Hence, during whole measurement and the data processing we were able to identify an accurate position on the tree in view of the scan. Some preliminary measurements on the trees were also conducted. They were performed using a GSSI 900 MHz antenna. Several tree species (beech, horse-chestnut, birch, ...) in Louvain-la-Neuve and Brussels, Belgium, have been investigated to see the internal structure of the tree decays. The measurements were carried out mainly by circumferential measurement around the trunk and also by vertical measurement along the trunk for approximate detection of the cavity. The comparison between the numerical simulations, simplified tree trunk model and real data from trees is presented. This research is funded by the Fonds de la Recherche Scientifique (FNRS, Belgium) and benefits from networking activities carried out within the EU COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

  13. Microwave remote sensing of flood inundation

    NASA Astrophysics Data System (ADS)

    Schumann, Guy J.-P.; Moller, Delwyn K.

    Flooding is one of the most costly natural disasters and thus mapping, modeling and forecasting flood events at various temporal and spatial scales is important for any flood risk mitigation plan, disaster relief services and the global (re-)insurance markets. Both computer models and observations (ground-based, airborne and Earth-orbiting) of flood processes and variables are of great value but the amount and quality of information available varies greatly with location, spatial scales and time. It is very well known that remote sensing of flooding, especially in the microwave region of the electromagnetic spectrum, can complement ground-based observations and be integrated with flood models to augment the amount of information available to end-users, decision-makers and scientists. This paper aims to provide a concise review of both the science and applications of microwave remote sensing of flood inundation, focusing mainly on synthetic aperture radar (SAR), in a variety of natural and man-made environments. Strengths and limitations are discussed and the paper will conclude with a brief account on perspectives and emerging technologies.

  14. Microwave Remote Sensing Modeling of Ocean Surface Salinity and Winds Using an Empirical Sea Surface Spectrum

    NASA Technical Reports Server (NTRS)

    Yueh, Simon H.

    2004-01-01

    Active and passive microwave remote sensing techniques have been investigated for the remote sensing of ocean surface wind and salinity. We revised an ocean surface spectrum using the CMOD-5 geophysical model function (GMF) for the European Remote Sensing (ERS) C-band scatterometer and the Ku-band GMF for the NASA SeaWinds scatterometer. The predictions of microwave brightness temperatures from this model agree well with satellite, aircraft and tower-based microwave radiometer data. This suggests that the impact of surface roughness on microwave brightness temperatures and radar scattering coefficients of sea surfaces can be consistently characterized by a roughness spectrum, providing physical basis for using combined active and passive remote sensing techniques for ocean surface wind and salinity remote sensing.

  15. Microwave-assisted hydrothermal synthesis of Cu/Cu2O hollow spheres with enhanced photocatalytic and gas sensing activities at room temperature.

    PubMed

    Zou, Xinwei; Fan, Huiqing; Tian, Yuming; Zhang, Mingang; Yan, Xiaoyan

    2015-05-01

    Cu/Cu2O nano-heterostructure hollow spheres with a submicron diameter (200-500 nm) were prepared by a microwave-assisted hydrothermal method using Cu(OAc)2·H2O, PVP and ascorbic acid solution as the precursors. The morphology of the products could evolve with the hydrothermal time from solid spheres to thick-shell hollow spheres, then to thin-shell hollow spheres, and finally to nanoparticles. Moreover, the content of Cu in the products could be controlled by adjusting the hydrothermal time. The spontaneous forming of the hollow structure spheres was found to result from the Ostwald ripening effect during the low temperature (100 °C) hydrothermal reaction process. The photocatalytic degradation activities on MO under visible-light irradiation and the gas sensing activities toward the oxidizing NO2 gas of different Cu/Cu2O nano-heterostructure hollow spheres were investigated. As a result, the Cu/Cu2O nano-heterostructure hollow spheres obtained at the hydrothermal time of 30 min, with a rough/porous thin-shell structure and a Cu content of about 10.5 wt%, exhibited the best photocatalytic and gas sensing performances compared with others. PMID:25820327

  16. Microwave remote sensing of flash droughts during crop growing seasons

    NASA Astrophysics Data System (ADS)

    Yuan, Xing; Ma, Zhuguo; Pan, Ming; Shi, Chunxiang

    2015-04-01

    Severe short-term droughts frequently occurred over China in recent years, with devastating impacts on crop production. Short-term droughts during the crop growing seasons sometimes occur together with abnormally high temperature, and positive feedbacks between the land and atmosphere often intensify the drought conditions. These droughts are recently termed as "flash droughts" due to their rapid development, unusual intensity and devastating impacts. This study assesses the capability of microwave remote sensing in detecting soil moisture droughts over China and in providing early warnings. The 22-year (1992-2013) satellite surface soil moisture retrievals produced by the European Space Agency Climate Change Initiative (ESA CCI) are compared against the in-situ observations at 312 stations in China, the ERA Interim and GLDAS soil moisture reanalysis, and the observed rainfall deficit. Both the reanalysis and remote sensing products can only detect less than 60% of drought months over most in-situ stations, but they capture the responses of inter-annual drought variations to ENSO at river basin scales quite well. As compared with reanalysis, the satellite products provide independent drought information over sparsely observed regions such as northwestern China, and the active microwave product with better vegetation penetration works the best in southern China. This study suggests that the microwave remote sensing data is useful for soil moisture drought monitor as well as verification for drought modeling or forecasting.

  17. Passive microwave remote sensing of the ocean - A review

    NASA Technical Reports Server (NTRS)

    Swift, C. T.

    1980-01-01

    This paper reviews the current status of passive microwave remote sensing of the ocean. The physics of emission and instrumentation are highlighted in order to establish a relationship between the thermal emission and retrieved geophysical parameters. A discussion then follows on measurements of temperature, salinity, windspeed, etc. using passive microwave systems. These measurements are related to the accuracy and spatial resolution required by the users. The status of passive microwave remote sensing is summarized and recommendations for future research are presented.

  18. Microwave Remote Sensing of Falling Snow

    NASA Technical Reports Server (NTRS)

    Kim, Min-Jeong; Wang, J. R.; Meneghini, R.; Johnson, B.; Tanelli, S.; Roman-Nieves, J. I.; Sekelsky, S. M.; Skofronick-Jackson, G.

    2005-01-01

    This study analyzes passive and active microwave measurements during the 2003 Wakasa Bay field experiment for understanding of the electromagnetic characteristics of frozen hydrometeors at millimeter-wave frequencies. Based on these understandings, parameterizations of the electromagnetic scattering properties of snow at millimeter-wave frequencies are developed and applied to the hydrometeor profiles obtained by airborne radar measurements. Calculated brightness temperatures and radar reflectivity are compared with the millimeter-wave measurements.

  19. Basic studies in microwave remote sensing

    NASA Technical Reports Server (NTRS)

    Fung, Adrian K.; Bredow, Jonathan

    1992-01-01

    Scattering models were developed in support of microwave remote sensing of earth terrains with particular emphasis on model applications to airborne Synthetic Aperture Radar measurements of forest. Practically useful surface scattering models based on a solution of a pair of integral equations including multiple scattering effects were developed. Comparisons of these models with controlled scattering measurements from statistically known random surfaces indicate that they are valid over a wide range of frequencies. Scattering models treating a forest environment as a two and three layered media were also developed. Extensive testing and comparisons were carried out with the two layered model. Further studies with the three layered model are being carried out. A volume scattering model valid for dense media such as a snow layer was also developed that shows the appropriate trend dependence with the volume fraction of scatterers.

  20. Active microwave users working group program planning

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Bare, J.; Brown, W. E., Jr.; Childs, L. F.; Dellwig, L. F.; Heighway, J. E.; Joosten, R.; Lewis, A. J.; Linlor, W.; Lundien, J. R.

    1978-01-01

    A detailed programmatic and technical development plan for active microwave technology was examined in each of four user activities: (1) vegetation; (2) water resources and geologic applications, and (4) oceanographic applications. Major application areas were identified, and the impact of each application area in terms of social and economic gains were evaluated. The present state of knowledge of the applicability of active microwave remote sensing to each application area was summarized and its role relative to other remote sensing devices was examined. The analysis and data acquisition techniques needed to resolve the effects of interference factors were reviewed to establish an operational capability in each application area. Flow charts of accomplished and required activities in each application area that lead to operational capability were structured.

  1. A Melting Layer Model for Passive/Active Microwave Remote Sensing Applications. Part 1; Model Formulation and Comparison with Observations

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Bauer, Peter; Viltard, Nicolas F.; Johnson, Daniel E.; Tao, Wei-Kuo

    2000-01-01

    In this study, a 1-D steady-state microphysical model which describes the vertical distribution of melting precipitation particles is developed. The model is driven by the ice-phase precipitation distributions just above the freezing level at applicable gridpoints of "parent" 3-D cloud-resolving model (CRM) simulations. It extends these simulations by providing the number density and meltwater fraction of each particle in finely separated size categories through the melting layer. The depth of the modeled melting layer is primarily determined by the initial material density of the ice-phase precipitation. The radiative properties of melting precipitation at microwave frequencies are calculated based upon different methods for describing the dielectric properties of mixed phase particles. Particle absorption and scattering efficiencies at the Tropical Rainfall Measuring Mission Microwave Imager frequencies (10.65 to 85.5 GHz) are enhanced greatly for relatively small (approx. 0.1) meltwater fractions. The relatively large number of partially-melted particles just below the freezing level in stratiform regions leads to significant microwave absorption, well-exceeding the absorption by rain at the base of the melting layer. Calculated precipitation backscatter efficiencies at the Precipitation Radar frequency (13.8 GHz) increase in proportion to the particle meltwater fraction, leading to a "bright-band" of enhanced radar reflectivities in agreement with previous studies. The radiative properties of the melting layer are determined by the choice of dielectric models and the initial water contents and material densities of the "seeding" ice-phase precipitation particles. Simulated melting layer profiles based upon snow described by the Fabry-Szyrmer core-shell dielectric model and graupel described by the Maxwell-Garnett water matrix dielectric model lead to reasonable agreement with radar-derived melting layer optical depth distributions. Moreover, control profiles

  2. Rough surface effects on active and passive microwave remote sensing of soil moisture at L-band using 3D fast solution of Maxwell's equations

    NASA Astrophysics Data System (ADS)

    Wang, Haogang; Liao, Tien-Hao; Shi, Jiancheng; Yu, Zherui

    2014-11-01

    The forthcoming Water Cycle Observation Mission (WCOM) is to understand the water cycle system among land, atmosphere, and ocean. In both active and passive microwave remote sensing of soil moisture, the surface roughness plays an important role. Electromagnetic models of roughness provide tables of emissivities and backscattering coefficients that can be used to retrieve soil moisture. In this paper, a fast and accurate three dimensional solution of Maxwell's equations is developed and employed to solve rough soil surface scattering problem at L-band. The algorithm combines QR Pre-Ranked Multilevel UV(MLUV) factorization and Hierarchical Fast Far Field Approximation. It is implemented using OpenMP interface for fast parallel calculation. In this algorithm, 1) QR based rank predetermined algorithm is derived to further compress the UV matrix pairs obtained using coarse-coarse sampling; 2) at the finer levels, MLUV is used straightforwardly to factorize the interactions between groups, while at the coarsest level, interactions between groups in the interaction list are calculated using an elegantly derived Hierarchical Fast Far Field Approximation (HFAFFA) to accelerate the calculation of interactions between large groups while keeping the accuracy of this approximation; 3) OpenMP interface is used to parallelize this new algorithm. Numerical results including the incoherent bistatic scattering coefficients and the emissivity demonstrate the efficiency of this method.

  3. Compressive sensing with a microwave photonic filter

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Yu, Xianbin; Chi, Hao; Zheng, Shilie; Zhang, Xianmin; Jin, Xiaofeng; Galili, Michael

    2015-03-01

    In this letter, we present a novel approach to realizing photonics-assisted compressive sensing (CS) with the technique of microwave photonic filtering. In the proposed system, an input spectrally sparse signal to be captured and a random sequence are modulated on an optical carrier via two Mach-Zehnder modulators (MZMs). Therefore, the mixing process (the signal to be captured mixing with the random sequence) is realized in the optical domain. The mixed optical signal then propagates through a length of dispersive fiber. As the double-sideband modulation in a dispersive optical link leads to a frequency-dependent power fading, low-pass filtering required in the CS is then realized. A proof-of-concept experiment for compressive sampling and recovery of a signal containing three tones at 310 MHz, 1 GHz and 2 GHz with a compression factor up to 10 is successfully demonstrated. More simulation results are also presented to recover signals within wider bandwidth and with more frequency components.

  4. A Melting Layer Model for Passive/Active Microwave Remote Sensing Applications. Part 2; Simulation of TRMM Observations

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Bauer, Peter; Kummerow, Christian D.; Tao, Wei-Kuo

    2000-01-01

    The one-dimensional, steady-state melting layer model developed in Part I of this study is used to calculate both the microphysical and radiative properties of melting precipitation, based upon the computed concentrations of snow and graupel just above the freezing level at applicable horizontal gridpoints of 3-dimensional cloud resolving model simulations. The modified 3-dimensional distributions of precipitation properties serve as input to radiative transfer calculations of upwelling radiances and radar extinction/reflectivities at the TRMM Microwave Imager (TMI) and Precipitation Radar (PR) frequencies, respectively. At the resolution of the cloud resolving model grids (approx. 1 km), upwelling radiances generally increase if mixed-phase precipitation is included in the model atmosphere. The magnitude of the increase depends upon the optical thickness of the cloud and precipitation, as well as the scattering characteristics of ice-phase precipitation aloft. Over the set of cloud resolving model simulations utilized in this study, maximum radiance increases of 43, 28, 18, and 10 K are simulated at 10.65, 19.35 GHz, 37.0, and 85.5 GHz, respectively. The impact of melting on TMI-measured radiances is determined not only by the physics of the melting particles but also by the horizontal extent of the melting precipitation, since the lower-frequency channels have footprints that extend over 10''s of kilometers. At TMI resolution, the maximum radiance increases are 16, 15, 12, and 9 K at the same frequencies. Simulated PR extinction and reflectivities in the melting layer can increase dramatically if mixed-phase precipitation is included, a result consistent with previous studies. Maximum increases of 0.46 (-2 dB) in extinction optical depth and 5 dBZ in reflectivity are simulated based upon the set of cloud resolving model simulations.

  5. Ocean waves. [remote sensing microwave measurement methods

    NASA Technical Reports Server (NTRS)

    Bartsch, N.; Vogel, M.; Kjelaas, A. G.; Parr, H.; Thomas, J.; Valenzuela, G.; Williams, P. D. L.; Shemdin, O. H.

    1978-01-01

    Ocean wave data can be obtained from such active microwave probe techniques as monostatic HF and VHF, bistatic HF, HF synthetic aperture radar, altimeters, satellite and airborne synthetic aperture radar, carrier wave or pulsed dual-frequency radars, and coastal surveillance radar. Approaches to texture analysis of ocean wave imagery are discussed, with attention given to transform techniques or spatial frequency analysis, and the analysis of second-order gray level statistics. In addition, recommendations are made for further work on the modulation of short gravity waves by longer waves as a function of wind speed and wave direction, and the derivation of transfer functions for the ocean response of dual-frequency radars.

  6. TCR backscattering characterization for microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Riccio, Giovanni; Gennarelli, Claudio

    2014-05-01

    A Trihedral Corner Reflector (TCR) is formed by three mutually orthogonal metal plates of various shapes and is a very important scattering structure since it exhibits a high monostatic Radar Cross Section (RCS) over a wide angular range. Moreover it is a handy passive device with low manufacturing costs and robust geometric construction, the maintenance of its efficiency is not difficult and expensive, and it can be used in all weather conditions (i.e., fog, rain, smoke, and dusty environment). These characteristics make it suitable as reference target and radar enhancement device for satellite- and ground-based microwave remote sensing techniques. For instance, TCRs have been recently employed to improve the signal-to-noise ratio of the backscattered signal in the case of urban ground deformation monitoring [1] and dynamic survey of civil infrastructures without natural corners as the Musmeci bridge in Basilicata, Italy [2]. The region of interest for the calculation of TCR's monostatic RCS is here confined to the first quadrant containing the boresight direction. The backscattering term is presented in closed form by evaluating the far-field scattering integral involving the contributions related to the direct illumination and the internal bouncing mechanisms. The Geometrical Optics (GO) laws allow one to determine the field incident on each TCR plate and the patch (integration domain) illuminated by it, thus enabling the use of a Physical Optics (PO) approximation for the corresponding surface current densities to consider for integration on each patch. Accordingly, five contributions are associated to each TCR plate: one contribution is due to the direct illumination of the whole internal surface; two contributions originate by the impinging rays that are simply reflected by the other two internal surfaces; and two contributions are related to the impinging rays that undergo two internal reflections. It is useful to note that the six contributions due to the

  7. Passive microwave sensing of coastal area waters

    NASA Technical Reports Server (NTRS)

    Kendall, B. M.

    1980-01-01

    A technique to remotely measure sea-surface temperature and salinity was demonstrated during the 1970's with a dual-frequency microwave radiometer system developed at the NASA Langley Research Center. Accuracies in temperature of 1 C and 1 part per thousand in salinity were obtained using state-of-the-art radiometers. Several aircraft programs for the measurement of coastal area waters demonstrating the application of the microwave radiometer system are discussed. Improvements of the microwave radiometer system during the 1980's and the design and development of new radiometer systems at other frequencies are outlined and related to potential applications.

  8. Technology transfer of NASA microwave remote sensing system

    NASA Technical Reports Server (NTRS)

    Akey, N. D.

    1981-01-01

    Viable techniques for effecting the transfer from NASA to a user agency of state-of-the-art airborne microwave remote sensing technology for oceanographic applications were studied. A detailed analysis of potential users, their needs and priorities; platform options; airborne microwave instrument candidates; ancillary instrumentation; and other, less obvious factors that must be considered were studied. Conclusions and recommendations for the development of an orderly and effective technology transfer of an airborne microwave system that could meet the specific needs of the selected user agencies are reported.

  9. Active touch sensing

    PubMed Central

    Prescott, Tony J.; Diamond, Mathew E.; Wing, Alan M.

    2011-01-01

    Active sensing systems are purposive and information-seeking sensory systems. Active sensing usually entails sensor movement, but more fundamentally, it involves control of the sensor apparatus, in whatever manner best suits the task, so as to maximize information gain. In animals, active sensing is perhaps most evident in the modality of touch. In this theme issue, we look at active touch across a broad range of species from insects, terrestrial and marine mammals, through to humans. In addition to analysing natural touch, we also consider how engineering is beginning to exploit physical analogues of these biological systems so as to endow robots with rich tactile sensing capabilities. The different contributions show not only the varieties of active touch—antennae, whiskers and fingertips—but also their commonalities. They explore how active touch sensing has evolved in different animal lineages, how it serves to provide rapid and reliable cues for controlling ongoing behaviour, and even how it can disintegrate when our brains begin to fail. They demonstrate that research on active touch offers a means both to understand this essential and primary sensory modality, and to investigate how animals, including man, combine movement with sensing so as to make sense of, and act effectively in, the world. PMID:21969680

  10. Applications of active microwave imagery

    NASA Technical Reports Server (NTRS)

    Weber, F. P.; Childs, L. F.; Gilbert, R.; Harlan, J. C.; Hoffer, R. M.; Miller, J. M.; Parsons, J.; Polcyn, F.; Schardt, B. B.; Smith, J. L.

    1978-01-01

    The following topics were discussed in reference to active microwave applications: (1) Use of imaging radar to improve the data collection/analysis process; (2) Data collection tasks for radar that other systems will not perform; (3) Data reduction concepts; and (4) System and vehicle parameters: aircraft and spacecraft.

  11. Beaufort/Bering 1979 microwave remote sensing data catalog report, 14-24 March 1979

    NASA Technical Reports Server (NTRS)

    Hirstein, W. S.; Hennigar, H. F.; Schaffner, S. K.; Delnore, V. E.; Grantham, W. L.

    1983-01-01

    The airborne microwave remote sending measurements obtained by the Langley Research Center in support of the 1979 Sea-Ice Radar Experiment (SIRE) in the Beaufort and Bering Seas are discussed. The remote sensing objective of SIRE was to define correlations between both active and passive microwave signatures and ice phenomena assocated with practical applications in the Arctic. The instruments used by Langley during SIRE include the stepped frequency microwave radiometer (SFMR), the airborne microwave scatterometer (AMSCAT), the precision radiation thermometer (PRT-5), and metric aerial photography. Remote sensing data are inventoried and cataloged in a user-friendly format. The data catalog is presented as time-history plots when and where data were obtained as well as the sensor configuration.

  12. Microwave electric field sensing with Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Stack, Daniel T.; Kunz, Paul D.; Meyer, David H.; Solmeyer, Neal

    2016-05-01

    Atoms form the basis of precise measurement for many quantities (time, acceleration, rotation, magnetic field, etc.). Measurements of microwave frequency electric fields by traditional methods (i.e. engineered antennas) have limited sensitivity and can be difficult to calibrate properly. Highly-excited (Rydberg) neutral atoms have very large electric-dipole moments and many dipole allowed transitions in the range of 1 - 500 GHz. It is possible to sensitively probe the electric field in this range using the combination of two quantum interference phenomena: electromagnetically induced transparency and the Autler-Townes effect. This technique allows for very sensitive field amplitude, polarization, and sub-wavelength imaging measurements. These quantities can be extracted by measuring properties of a probe laser beam as it passes through a warm rubidium vapor cell. Thus far, Rydberg microwave electrometry has relied upon the absorption of the probe laser. We report on our use of polarization rotation, which corresponds to the real part of the susceptibility, for measuring the properties of microwave frequency electric fields. Our simulations show that when a magnetic field is present and directed along the optical propagation direction a polarization rotation signal exists and can be used for microwave electrometry. One central advantage in using the polarization rotation signal rather than the absorption signal is that common mode laser noise is naturally eliminated leading to a potentially dramatic increase in signal-to-noise ratio.

  13. Microwave dielectric method for moisture sensing almonds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A dielectric –based method was developed for rapid and nondestructive determination of moisture content in almond kernels independent of bulk density from measurement of their dielectric properties at a single microwave frequency. Calibration equations for moisture determination with temperature com...

  14. Passive Microwave Remote Sensing for Land Applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Land applications, in particular soil moisture retrieval, have been hampered by the lack of low frequency passive microwave observations and the coarse spatial resolution of existing sensors. The next decade could see several improved operational and exploratory missions using new technologies as w...

  15. Microwave remote sensing of sea ice in the AIDJEX Main Experiment

    USGS Publications Warehouse

    Campbell, W.J.; Wayenberg, J.; Ramseyer, J.B.; Ramseier, R.O.; Vant, M.R.; Weaver, R.; Redmond, A.; Arsenaul, L.; Gloersen, P.; Zwally, H.J.; Wilheit, T.T.; Chang, T.C.; Hall, D.; Gray, L.; Meeks, D.C.; Bryan, M.L.; Barath, F.T.; Elachi, C.; Leberl, F.; Farr, Tom

    1978-01-01

    During the AIDJEX Main Experiment, April 1975 through May 1976, a comprehensive microwave sensing program was performed on the sea ice of the Beaufort Sea. Surface and aircraft measurements were obtained during all seasons using a wide variety of active and passive microwave sensors. The surface program obtained passive microwave measurements of various ice types using four antennas mounted on a tracked vehicle. In three test regions, each with an area of approximately 1.5 ?? 104 m2, detailed ice crystallographic, dielectric properties, and brightness temperatures of first-year, multiyear, and first-year/multiyear mixtures were measured. A NASA aircraft obtained passive microwave measurements of the entire area of the AIDJEX manned station array (triangle) during each of 18 flights. This verified the earlier reported ability to distinguish first-year and multiyear ice types and concentration and gave new information on ways to observe ice mixtures and thin ice types. The active microwave measurements from aircraft included those from an X- and L-band radar and from a scatterometer. The former is used to study a wide variety of ice features and to estimate deformations, while both are equally usable to observe ice types. With the present data, only the scatterometer can be used to distinguish positively multiyear from first-year and various types of thin ice. This is best done using coupled active and passive microwave sensing. ?? 1978 D. Reidel Publishing Company.

  16. Microwave Remote Sensing and the Cold Land Processes Field Experiment

    NASA Technical Reports Server (NTRS)

    Kim, Edward J.; Cline, Don; Davis, Bert; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    The Cold Land Processes Field Experiment (CLPX) has been designed to advance our understanding of the terrestrial cryosphere. Developing a more complete understanding of fluxes, storage, and transformations of water and energy in cold land areas is a critical focus of the NASA Earth Science Enterprise Research Strategy, the NASA Global Water and Energy Cycle (GWEC) Initiative, the Global Energy and Water Cycle Experiment (GEWEX), and the GEWEX Americas Prediction Project (GAPP). The movement of water and energy through cold regions in turn plays a large role in ecological activity and biogeochemical cycles. Quantitative understanding of cold land processes over large areas will require synergistic advancements in 1) understanding how cold land processes, most comprehensively understood at local or hillslope scales, extend to larger scales, 2) improved representation of cold land processes in coupled and uncoupled land-surface models, and 3) a breakthrough in large-scale observation of hydrologic properties, including snow characteristics, soil moisture, the extent of frozen soils, and the transition between frozen and thawed soil conditions. The CLPX Plan has been developed through the efforts of over 60 interested scientists that have participated in the NASA Cold Land Processes Working Group (CLPWG). This group is charged with the task of assessing, planning and implementing the required background science, technology, and application infrastructure to support successful land surface hydrology remote sensing space missions. A major product of the experiment will be a comprehensive, legacy data set that will energize many aspects of cold land processes research. The CLPX will focus on developing the quantitative understanding, models, and measurements necessary to extend our local-scale understanding of water fluxes, storage, and transformations to regional and global scales. The experiment will particularly emphasize developing a strong synergism between process

  17. Passive microwave remote sensing of salinity in coastal zones

    NASA Technical Reports Server (NTRS)

    Swift, Calvin T.; Blume, Hans-Juergen C.; Kendall, Bruce M.

    1987-01-01

    The theory of measuring coastal-zone salinity from airborne microwave radiometers is developed. The theory, as presented, shows that precision measurements of salinity favor the lower microwave frequencies. To this end, L- and S-Band systems were built, and the flight results have shown that accuracies of at least one part per thousand were achieved.The aircraft results focus on flights conducted over the Chesapeake Bay and the mouth of the Savanna River off the Georgia Coast. This paper presents no new work, but rather summarizes the capabilities of the remote sensing technique.

  18. Microwave remote sensing of short-term droughts during crop growing seasons

    NASA Astrophysics Data System (ADS)

    Yuan, Xing; Ma, Zhuguo; Pan, Ming; Shi, Chunxiang

    2015-06-01

    Severe short-term (monthly to seasonal) droughts frequently occurred over China in recent years, with devastating impacts on crop production. This study assesses the capability of microwave remote sensing in detecting soil moisture (agricultural) droughts over China and in providing early warnings. The 22 year (1992-2013) European Space Agency satellite soil moisture retrievals are compared against the in situ observations at 312 stations in China, the global soil moisture reanalysis, and the observed rainfall deficit. Both the reanalysis and remote sensing products can only detect less than 60% of drought months at in situ station scale, but they capture the interannual variations of short-term drought area at river basin scales quite well. As compared with reanalysis, the passive and merged microwave products have better drought detection over sparsely vegetated regions in northwestern China and the active microwave product with better vegetation penetration works the best in eastern China.

  19. Application of Terrestrial Microwave Remote Sensing to Agricultural Drought Monitoring

    NASA Astrophysics Data System (ADS)

    Crow, W. T.; Bolten, J. D.

    2014-12-01

    Root-zone soil moisture information is a valuable diagnostic for detecting the onset and severity of agricultural drought. Current attempts to globally monitor root-zone soil moisture are generally based on the application of soil water balance models driven by observed meteorological variables. Such systems, however, are prone to random error associated with: incorrect process model physics, poor parameter choices and noisy meteorological inputs. The presentation will describe attempts to remediate these sources of error via the assimilation of remotely-sensed surface soil moisture retrievals from satellite-based passive microwave sensors into a global soil water balance model. Results demonstrate the ability of satellite-based soil moisture retrieval products to significantly improve the global characterization of root-zone soil moisture - particularly in data-poor regions lacking adequate ground-based rain gage instrumentation. This success has lead to an on-going effort to implement an operational land data assimilation system at the United States Department of Agriculture's Foreign Agricultural Service (USDA FAS) to globally monitor variations in root-zone soil moisture availability via the integration of satellite-based precipitation and soil moisture information. Prospects for improving the performance of the USDA FAS system via the simultaneous assimilation of both passive and active-based soil moisture retrievals derived from the upcoming NASA Soil Moisture Active/Passive mission will also be discussed.

  20. Microwave remote sensing of snow experiment description and preliminary results

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T. (Principal Investigator); Stiles, W. H.; Hanson, B. C.

    1977-01-01

    The active and passive microwave responses to snow were investigated at a site near Steamboat Springs, Colorado during the February and March winter months. The microwave equipment was mounted atop truck-mounted booms. Data were acquired at numerous frequencies, polarizations, and angles of incidence for a variety of snow conditions. The experiment description, the characteristics of the microwave and ground truth instruments, and the results of a preliminary analysis of a small portion of the total data volume acquired in Colorado are documented.

  1. Remote sensing of soil moisture with microwave radiometers

    NASA Technical Reports Server (NTRS)

    Schmugge, T.; Wilheit, T.; Webster, W., Jr.; Gloerson, P.

    1976-01-01

    Results are presented that were derived from measurements made by microwave radiometers during the March 1972 and February 1973 flights of National Aeronautics and Space Administration (NASA) Convair-9900 aircraft over agricultural test sites in the southwestern part of United States. The purpose of the missions was to study the use of microwave radiometers for the remote sensing of soil moisture. The microwave radiometers covered the 0.8- to 21-cm wavelength range. The results show a good linear correlation between the observed microwave brightness temperature and moisture content of the 0- to 1-cm layer of the soil. The results at the largest wavelength (21 cm) show the greatest sensitivity to soil moisture variations and indicate the possibility of sensing these variations through a vegetative canopy. The effect of soil texture on the emission from the soil was also studied and it was found that this effect can be compensated for by expressing soil moisture as a percent of field capacity for the soil. The results were compared with calculations based on a radiative transfer model for layered dielectrics and the agreement is very good at the longer wavelengths. At the shorter wavelengths, surface roughness effects are larger and the agreement becomes poorer.

  2. Aperture synthesis concepts in microwave remote sensing of the earth

    NASA Technical Reports Server (NTRS)

    Swift, Calvin T.; Le Vine, David M.; Ruf, Christopher S.

    1991-01-01

    The application of aperture synthesis concepts, used for many years in radio astronomy to achieve high image resolution at a reasonable cost, to remote sensing technology is discussed. The electronically scanned thinned array radiometer (ESTAR) is put forward as a viable alternative to improve spatial resolution by an order of magnitude over what is presently achieved by microwave imaging systems that are collecting data from earth orbit. Future developments in airborne sensor technology and potential spacecraft application are described.

  3. Applications of Microwaves to Remote Sensing of Terrain

    NASA Technical Reports Server (NTRS)

    Porter, R. A.

    1975-01-01

    A survey and study was conducted to define the role that microwaves may play in the measurement of a variety of terrain-related parameters. The survey consisted of discussions with many users and researchers in the field of remote sensing. In addition, a survey questionnaire was prepared and replies were solicited from these and other users and researchers. The results of the survey, and associated bibliography, were studied and conclusions were drawn as to the usefulness of radiometric systems for remote sensing of terrain.

  4. Microwave and THz sensing using slab-pair-based metamaterials

    SciTech Connect

    Kenanakis, G.; Shen, Nianhai; Mavidis, Ch.; Katsarakis, N.; Kafesaki, M.; Soukoulis, Costas M.; Economou, E.N.

    2012-10-15

    In this work the sensing capability of an artificial magnetic metamaterial based on pairs of metal slabs is demonstrated, both theoretically and experimentally, in the microwave regime. The demonstration is based on transmission measurements and simulations monitoring the shift of the magnetic resonance frequency as one changes a thin dielectric layer placed between the slabs of the pairs. Strong dependence of the magnetic resonance frequency on both the permittivity and the thickness of the dielectric layer under detection was observed. The sensitivity to the dielectrics′ permittivity (ε) is larger for dielectrics of low ε values, which makes the approach suitable for sensing organic materials also in the THz regime. The capability of our approach for THz sensing is also demonstrated through simulations.

  5. [Atmospheric Influences Analysis on the Satellite Passive Microwave Remote Sensing].

    PubMed

    Qiu, Yu-bao; Shi, Li-juan; Shi, Jian-cheng; Zhao, Shao-jie

    2016-02-01

    Passive microwave remote sensing offers its all-weather work capabilities, but atmospheric influences on satellite microwave brightness temperature were different under different atmospheric conditions and environments. In order to clarify atmospheric influences on Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E), atmospheric radiation were simulated based on AMSR-E configuration under clear sky and cloudy conditions, by using radiative transfer model and atmospheric conditions data. Results showed that atmospheric water vapor was the major factor for atmospheric radiation under clear sky condition. Atmospheric transmittances were almost above 0.98 at AMSR-E's low frequencies (< 18.7 GHz) and the microwave brightness temperature changes caused by atmosphere can be ignored in clear sky condition. Atmospheric transmittances at 36.5 and 89 GHz were 0.896 and 0.756 respectively. The effects of atmospheric water vapor needed to be corrected when using microwave high-frequency channels to inverse land surface parameters in clear sky condition. But under cloud cover or cloudy conditions, cloud liquid water was the key factor to cause atmospheric radiation. When sky was covered by typical stratus cloud, atmospheric transmittances at 10.7, 18.7 and 36.5 GHz were 0.942, 0.828 and 0.605 respectively. Comparing with the clear sky condition, the down-welling atmospheric radiation caused by cloud liquid water increased up to 75.365 K at 36.5 GHz. It showed that the atmospheric correction under different clouds covered condition was the primary work to improve the accuracy of land surface parameters inversion of passive microwave remote sensing. The results also provided the basis for microwave atmospheric correction algorithm development. Finally, the atmospheric sounding data was utilized to calculate the atmospheric transmittance of Hailaer Region, Inner Mongolia province, in July 2013. The results indicated that atmospheric transmittances were close to 1

  6. Assimilation of Passive and Active Microwave Soil Moisture Retrievals

    NASA Technical Reports Server (NTRS)

    Draper, C. S.; Reichle, R. H.; DeLannoy, G. J. M.; Liu, Q.

    2012-01-01

    Root-zone soil moisture is an important control over the partition of land surface energy and moisture, and the assimilation of remotely sensed near-surface soil moisture has been shown to improve model profile soil moisture [1]. To date, efforts to assimilate remotely sensed near-surface soil moisture at large scales have focused on soil moisture derived from the passive microwave Advanced Microwave Scanning Radiometer (AMSR-E) and the active Advanced Scatterometer (ASCAT; together with its predecessor on the European Remote Sensing satellites (ERS. The assimilation of passive and active microwave soil moisture observations has not yet been directly compared, and so this study compares the impact of assimilating ASCAT and AMSR-E soil moisture data, both separately and together. Since the soil moisture retrieval skill from active and passive microwave data is thought to differ according to surface characteristics [2], the impact of each assimilation on the model soil moisture skill is assessed according to land cover type, by comparison to in situ soil moisture observations.

  7. Study of blood flow sensing with microwave radiometry

    NASA Technical Reports Server (NTRS)

    Porter, R. A.; Wentz, F. J., III

    1973-01-01

    A study and experimental investigation has been performed to determine the feasibility of measuring regional blood flow and volume in man by means of microwave radiometry. An indication was expected of regional blood flow from measurement of surface and subsurface temperatures with a sensitive radiometer. Following theoretical modeling of biological tissue, to determine the optimum operating frequency for adequate sensing depth, a sensitive microwave radiometer was designed for operation at 793 MHz. A temperature sensitivity of of 0.06 K rms was realized in this equipment. Measurements performed on phantom tissue models, consisting of beef fat and lean beefsteak showed that the radiometer was capable of sensing temperatures from a depth between 3.8 and 5.1 cm. Radiometric and thermodynamic temperature measurements were also performed on the hind thighs of large dogs. These showed that the radiometer could sense subsurface temperatures from a depth of, at least, 1.3 cm. Delays caused by externally-generated RF interference, coupled with the lack of reliable blood flow measurement equipment, prevented correlation of radiometer readings with reginal blood flow. For the same reasons, it was not possible to extend the radiometric observations to human subjects.

  8. Summary of the Active Microwave Workshop, chapter 1. [utilization in applications and aerospace programs

    NASA Technical Reports Server (NTRS)

    1975-01-01

    An overview is given of the utility, feasibility, and advantages of active microwave sensors for a broad range of applications, including aerospace. In many instances, the material provides an in-depth examination of the applicability and/or the technology of microwave remote sensing, and considerable documentation is presented in support of these techniques. An assessment of the relative strengths and weaknesses of active microwave sensor data indicates that satisfactory data are obtainable for several significant applications.

  9. Estimation of snow-cover parameters using a combination of microwave and optical remote sensing data

    NASA Astrophysics Data System (ADS)

    Ghedira, H.; Arevalo, J. C.; Khanbilvardi, R.

    2004-05-01

    Snow-cover parameters are being increasingly used as input to hydrological models. Furthermore, an accurate knowledge of the onset of snow melts and snow water equivalent values are important variables in different hydrological applications such as flooding prediction, reservoir management and agricultural activities. However, the traditional field sampling methods and the ground-based data collection are often very sparse, time consuming, and expensive compared to the coverage provided by remote sensing techniques. Various remote sensing techniques have been evaluated and proven to be an effective tool for snow mapping. In particular, microwave remote sensing techniques have been investigated by numerous researchers using various sensors and have been demonstrated to be effective for monitoring snow pack parameters such as spatial and temporal distribution, snow water equivalent, depth, and snow condition (wet/dry state). Those researches have resulted that the microwave brightness temperature and the microwave backscattering are related to the snow cover structure with different correlation degrees. The primary objective of this research is to produce a spatial estimation of snow water equivalent in a timely fashion with sufficient spatial and temporal resolution using multi-source microwave and optical data. The final product of this project will be an additional tool for flood warning and water resource forecasts, which can be an additional input to the actual hydrological models. The contribution of remote sensing snow related information into the advanced hydrologic prediction system (AHPS) operated by NWS/NOAA (with 4 km grid resolution) will be also evaluated. The study area is located in the north of the state of New York (42-44 N and 73-78 W). A variety of multitemporal remote sensing data (SSM/I, RADARSAT and AVHRR) acquired during three successive winters (1999-2000, 2000-2001, and 2001-2002) have been provided for this project.

  10. Landscape Temperature and Frozen/Thawed Condition over Alaska with Infrared and Active/Passive Microwave Remote Sensing: Determination of Thermal Controls on Land-Atmosphere Carbon Flux in Support of CARVE

    NASA Astrophysics Data System (ADS)

    Steiner, N.; McDonald, K. C.; Schroeder, R.; Miller, C. E.; Dinardo, S.

    2013-12-01

    The freeze/thaw (F/T) state of the Earth's land surface has a considerable influence on the terrestrial water, energy and carbon cycles. This is especially true in F/T dominated areas such as the Arctic and boreal regions where F/T cycles will often bracket negative and positive modes in carbon flux between the surface and atmosphere. Observations from a Forward-Looking Infrared (FLIR) thermal imaging camera, flown during the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) in the summer of 2013, are used to determine the temperature and F/T state of the surface at a high resolution. We assess the high-resolution data product with concurrent satellite-based observations in the thermal-infrared using the Moderate Resolution Imaging Spectroradiometer (MODIS) and in the microwave from a combination of C-band active and passive instruments. Passive and active microwave observation are provided by the Advanced Microwave Scanning Radiometer (AMSR2) on JAXA's Shizuku (GCOM-W1) satellite and Advanced Scatterometer (ASCAT) aboard the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) MetOp-A respectively. In addition to the evaluation airborne thermal observations we provide comparisons of the satellite land surface temperature and F/T products because F/T determination from surface kinetic temperature is based on different physical properties than similar microwave data-records. The high resolution surface observations are also used to illustrate how small-scale thermal features, important in biogeochemical cycling, will scale to coarse resolution satellite products. The accuracy of remote sensing data-sets are evaluated using shallow soil temperatures from stations in the Alaska Ecological Transect (ALECTRA), Soil Climate Analysis Network (SCAN), and Snowpack Telemetry (SNOTEL) networks. The spatial and temporal co-registration and covariant analysis of all gridded datasets are performed within SciDB (www.scidb.org), an array

  11. Remote sensing of soil moisture with microwave radiometers

    NASA Technical Reports Server (NTRS)

    Schmugge, T.; Gloersen, P.; Wilheit, T.; Geiger, F.

    1974-01-01

    Microwave radiometry has been used for the remote sensing of soil moisture in a series of aircraft flights over an agricultural test area in the vicinity of Phoenix, Arizona. The radiometers covered the wavelength range 0.8-21 cm. Ground truth in the form of gravimetric measurements of the soil moisture in the top 15 cm were obtained for 200 fields at this site. The results indicate that it is possible to monitor moisture variations with airborne radiometers. The emission is a function of the radiometer wavelength and the distribution of the moisture in the soil. At a wavelength of 1.55 cm there is little or no variation in the emission for soil moisture values below 10 or 15% moisture content by weight. Above this value, there is a linear decrease in the emission with a slope of approximately 3 K for each percentage point increase in soil moisture.

  12. Microwave sensing of physiological movement and volume change: a review.

    PubMed

    Lin, J C

    1992-01-01

    The ability non-invasively to detect and monitor the movement of tissues and organs from outside the body provides many worthwhile areas of potential biomedical applications. Several non-invasive microwave techniques for contact and remote sensing of circulatory and respiratory movements and volume changes have been developed. In general, these systems consist of a microwave generator, a sampling device, a transmitting-receiving antenna, a set of signal-conditioning and processing devices, and a display unit. They operate at continuous-wave frequencies between 1 and 35 GHz and make use of amplitude and phase information derived from the received signal. The average power density of energy radiated by present systems ranges from approximately 0.001-1.0 mW/cm2. These systems are capable of registering instantaneous changes in fluid volume, pressure pulse, heart rate, and respiration rate in contact with body surface or at distances greater than 30 m, or behind thick layers of non-conductive walls. PMID:1482418

  13. Retrieving of surface parameters with microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Wang, Jiemin; Gao, Feng; Li, Xin; Koike, Toshio

    2003-07-01

    In addition to investigate the rainfall over the Tibetan Plateau, Microwave Imager observations on board of the satellite Tropical Rainfall Measurement Mission (TRMM) have been also used to retrieve land surface parameters, such as sur-face temperature (Te), vegetation water content (Wc), and volumetric soil surface moisture (Mv). A three dimensional Look-up Table (LUT) scheme, by using one band brightness temperature, a 'Polarization Index' (PI), and an 'Index for Soil Wetness' (ISW), was developed for this purpose, which can retrieve the three basic parameters Te, Wc, and Mv simultaneously. Considered that there are still clouds as well as heavy rainfall disturbance in deriving surface parameters over the Tibetan Plateau, 10-day composite TMI images were used. For the five months from May to September 1998, the distribution of surface parameters of each ten days on the mesoscale intensive experimental region of GAME-Tibet was evaluated. The results were compared with field observations; particularly, for the most concerned surface soil moisture, the results are quite acceptable. 3-D LUT is an easy and effective method to be used in the passive microwave remote sensing.

  14. Radiometer system requirements for microwave remote sensing from satellites

    NASA Technical Reports Server (NTRS)

    Juang, Jeng-Nan

    1990-01-01

    An area of increasing interest is the establishment of a significant research program in microwave remote sensing from satellites, particularly geosynchronous satellites. Due to the relatively small resolution cell sizes, a severe requirement is placed on beam efficiency specifications for the radiometer antenna. Geostationary satellite microwave radiometers could continuously monitor several important geophysical parameters over the world's oceans. These parameters include the columnar content of atmospheric liquid water (both cloud and rain) and water vapor, air temperature profiles, and possibly sea surface temperature. Two principle features of performance are of concern. The first is the ability of the radiometer system to resolve absolute temperatures with a very small absolute error, a capability that depends on radiometer system stability, on frequency bandwidth, and on footprint dwell time. The second is the ability of the radiometer to resolve changes in temperature from one resolution cell to the next when these temperatures are subject to wide variation over the overall field-of-view of the instrument. Both of these features are involved in the use of the radiometer data to construct high-resolution temperature maps with high absolute accuracy.

  15. Soil surface roughness characterization for microwave remote sensing applications

    NASA Astrophysics Data System (ADS)

    Marzahn, P.; Rieke-Zapp, D.; Ludwig, R.

    2012-04-01

    With this poster we present a simple and efficient method to measure soil surface roughness in an agricultural environment. Micro scale soil surface roughness is a crucial parameter in many environmental applications. In recent studies it is strongly recognized that soil surface roughness significantly influences the backscatter of agricultural surface, especially on bare fields. Indeed, while different roughness indices depend on their measurement length, no satisfying roughness parametrization and measurement technique has been found yet, introducing large uncertainty in the interpretation of the radar backscattering. In this study, we introduce a photogrammetric system which consists of a customized consumer grade Canon EOS 5d camera and a reference frame providing ground control points. With the system one can generate digital surface models (DSM) with a minimum size of 1 x 2.5 m2, extendable to any desired size, with a ground x,y- resolution of 2 mm. Using this approach, we generated a set of DSM with sizes ranging from 2.5 m2 to 22 m2, acquired over different roughness conditions representing ploughed, harrowed as well as crusted fields on different test sites. For roughness characterization we calculated in microwave remote sensing common roughness indices such as the RMS- height s and the autocorrelation length l. In an extensive statistical investigation we show the behavior of the roughness indices for different acquisition sizes of the proposed method. Results indicate, compared to results from profiles generated out of the dataset, that using a three dimensional measuring device, the calculated roughness indices are more robust in their estimation. In addition, a strong directional dependency of the proposed roughness indices was observed which could be related to the orientation of the seedbed rows to the acqusition direction. In a geostatistical analysis, we decomposed the acquired roughness indices into different scales, yielding a roughness quantity

  16. Microwave remote sensing in atmospheric research and meteorology (invited)

    NASA Astrophysics Data System (ADS)

    Kunzi, K.

    Remote sensing techniques to investigate the atmosphere are widely used. Sensors operating in the microwave range (wavelength from 10 to 0.1 cm) of the electromagnetic spectrum were among the first instruments used on the ground and on air- and space borne platforms for this purpose. These instruments measure the thermal emission from molecular resonances or use the absorption and scattering properties of water droplets or particles to obtain information on atmospheric parameters and composition. In the seventies the sensors NEMS and SCAMS on the Nimbus-5 and 6 satellites have demonstrated the big advantage of these instruments to obtain temperature profiles, amounts of water vapor and liquid water nearly unaffected by cloud coverage. The frequency bands and observing geometries selected for these early instruments are still used to day very successfully for the operational sensors on the polar orbiting satellites of the DMSP and NOAA series. In the eighties and nineties the very much improved sensor technology allowed to extend the spectral range to wavelength near 0.01 cm. It is now possible to observe key constituents of importance in atmospheric chemistry, and in particular related to stratospheric ozone. Such sensors have been flown on UARS (MLS), several space shuttle missions (MAS) and on stratospheric balloons using limb sounding geometry, and also on research aircraft (NASA DC-9, the DLR Falcon and others), furthermore microwave radiometers are considered key sensors for the ground based, global Network for the Detection of Stratospheric Change (NDSC). The next generation of sensors on future satellites such as AURA (MLS) and the international space station (SMILES) are making use of higher frequencies and superconducting receiver technology. This will allow to measure more minor constituents with higher accuracy and better temporal resolution. Today the receiver technology is very mature down to wavelength of 0.03 cm. Planned future applications include a

  17. Microwave spectroscopy of chemical warfare agents: prospects for remote sensing

    NASA Astrophysics Data System (ADS)

    Samuels, Alan C.; Jensen, James O.; Suenram, Richard D.; Hight Walker, Angela R.; Woolard, Dwight L.

    1999-07-01

    The high level of interest in the sensor development community in millimeter wave technology development demonstrates the potential for several multipurpose applications of millimeter wave sensors. The potential for remote sensing of hazardous chemical materials based on their millimeter wave rotational signatures is yet another possible applications, offering certain distinct advantages over FTIR remote sensing. The high specificity of the rotational spectra to the molecular structures affords the capability of detecting chemical warfare (CW) agents and degradation products in complex mixtures including water vapor and smoke, an important consideration in military applications. Furthermore, the rotational modes are not complicated by electronic or vibrational transitions, reducing the potential for false alarms. We have conducted microwave spectroscopic measurements on two CW nerve agents (sarin and soman) and one blister agent (H-mustard). The assignment of the observed band furnishes us with an extremely accurate tool for predicting the rotational spectrum of these agents at any arbitrary frequency. By factoring in the effects of pressure (Lorentzian broadening and intensity reduction), we present the predicted spectral signatures of the CW agents in the 80 - 300 GHz region. This frequency regime is important for atmospheric monitoring as it exploits the wide bandwidth capability of millimeter wave sensors as well as the atmospheric windows that occur in this region.

  18. Passive microwave remote sensing of forests: A model investigation

    SciTech Connect

    Ferrazzoli, P.; Guerriero, L.

    1996-03-01

    In the recent years, several studies have been carried out to investigate the potential of microwave sensors in forest parameter monitoring. A stimulus has been given by the increasing impact of some environmental problems, like desertification, climatic change, and carbon dioxide concentration. These problems have some connections with forests extension and health; on the other hand, optical systems, which proved their effectiveness in sensing leaf parameters, are not able to sense the woody biomass. A model, based on the radiative transfer theory and the matrix doubling algorithm, is described and used to compute the emissivity e of forests. According to model simulations, the L-band emissivity trend versus forest biomass is more gradual than that of the backscatter coefficient. This gradual behavior is observed, in absence of leaves, also at C and X bands, while leaves anticipate saturation and make e higher in coniferous forests and lower in deciduous forests. Model results are successfully validated by some available experimental data. Operational aspects, concerning the potential of airborne and spaceborne radiometers in identifying forest type and estimating biomass, are discussed.

  19. Microwave remote sensing and radar polarization signatures of natural fields

    NASA Technical Reports Server (NTRS)

    Mo, Tsan

    1989-01-01

    Theoretical models developed for simulation of microwave remote sensing of the Earth surface from airborne/spaceborne sensors are described. Theoretical model calculations were performed and the results were compared with data of field measurements. Data studied included polarimetric images at the frequencies of P band, L band, and C band, acquired with airborne polarimeters over a agricultural field test site. Radar polarization signatures from bare soil surfaces and from tree covered fields were obtained from the data. The models developed in this report include: (1) Small perturbation model of wave scatterings from randomly rough surfaces, (2) Physical optics model, (3) Geometrical optics model, and (4) Electromagnetic wave scattering from dielectric cylinders of finite lengths, which replace the trees and branches in the modeling of tree covered field. Additionally, a three-layer emissivity model for passive sensing of a vegetation covered soil surface is also developed. The effects of surface roughness, soil moisture contents, and tree parameters on the polarization signatures were investigated.

  20. Microbead-assisted high resolution microwave planar ring resonator for organic-vapor sensing

    NASA Astrophysics Data System (ADS)

    Zarifi, Mohammad H.; Fayaz, Mohammadreza; Goldthorp, Jordan; Abdolrazzaghi, Mohammad; Hashisho, Zaher; Daneshmand, Mojgan

    2015-02-01

    A microbead-assisted planar microwave resonator for organic vapor sensing applications is presented. The core of this sensor is a planar microstrip split-ring resonator, integrated with an active feedback loop to enhance the initial quality factor from 200 to ˜1 M at an operational resonance frequency of 1.42 GHz. Two different types of microbeads, beaded activated carbon (BAC) and polymer based (V503) beads, are investigated in non-contact mode for use as gas adsorbents in the gas sensing device. 2-Butoxyethanol (BE) is used in various concentrations as the target gas, and the transmitted power (S21) of the two port resonator is measured. The two main microwave parameters of resonance frequency and quality factor are extracted from S21 since these parameters are less susceptible to environmental and instrumental noise than the amplitude. Measured results demonstrate a minimum resonance frequency shift of 10 kHz for a 35 ppm concentration of BE exposure to carbon beads and 160 kHz for the polymer based adsorbent at the same concentration. The quality factor of the resonator also changed for different concentrations, but a distinguishable variation is observed for the BAC adsorbents. The high quality factor of the sensor provides the opportunity of real time monitoring of the adsorbent behaviors in remote sensing mode with very high resolution.

  1. Synergies of the European Microwave Remote Sensing Missions SMOS and ASCAT for Monitoring Soil Moisture

    NASA Astrophysics Data System (ADS)

    Scipal, K.; Wagner, W.

    2003-04-01

    The lack of global soil moisture observations is one of the most glaring and pressing deficiencies in current research activities of related fields, from climate monitoring and ecological applications to the quantification of biogeophysical fluxes. This has implications for important issues of the international political agenda like managing global water resources, securing food production and studying climate change. Currently it is held that only microwave remote sensing offers the potential to produce reliable global scale soil moisture information economically. Recognising the urgent need for a soil moisture mission several international initiatives are planning satellite missions dedicated to monitor the global hydrological cycle among them two European microwave satellites. ESA is planning to launch the Soil Moisture and Ocean Salinity Mission SMOS, in 2006. SMOS will measure soil moisture over land and ocean salinity over the oceans. The mission rests on a passive microwave sensor (radiometer) operated in L-band which is currently believed to hold the largest potential for soil moisture retrieval. One year before (2005) EUMETSAT will launch the Meteorological Operational satellite METOP which carries the active microwave system Advanced Scatterometer ASCAT on board. ASCAT has been designed to retrieve winds over the oceans but recent research has established its capability to retrieve soil moisture. Although currently it is hold that, using active microwave techniques, the effect of surface roughness dominates that of soil moisture (while the converse is true for radiometers), the ERS scatterometer was successfully used to derive global soil moisture information at a spatial resolution of 50 km with weekly to decadal temporal resolution. The quality of the soil moisture products have been assessed by independent experts in several pilot projects funded by the European Space Agency. There is evidence to believe that both missions will provide a flow of

  2. Thickness characterisation of oil spills using active microwave sensors

    NASA Astrophysics Data System (ADS)

    True, Michael; Shuchman, Robert A.; Kletzli, D. W., Jr.; Johannessen, Johnny A.; Digranes, Gunar; Berg, Sverre; Dalland, Kjell

    1994-12-01

    Oil thickness is a crucial parameter in the characterization of oil spills for environmental impact. The feasibility of using active microwave sensors to measure thickness was addressed in a series of microwave scatterometer experiments performed by Simrad Marine A/S in a wave tank at the Nansen Environmental Remote Sensing Center. The thickness of the oil layer was maintained at levels similar to the thick part of an oil spill (0.1 - 1 mm). The measurements showed the capability of active microwave sensors to measure oil spill thickness when the oil type is known. In addition to thickness characterization, the experiment studied the effects of oil viscosity, incidence angle, wind speed, wind angle, microwave frequency, and polarization. The backscatter contrast was observed to be greater for lower incidence angles which indicates that the ERS-1 viewing geometry is optimum for the detection and measurement of thick oil slicks. A thickness-dependent backscatter model was developed which included the effects of oil viscosity, composite surface effects, and oil-water reflectivities. The model viscous effects saturated when the oil thickness was greater than the viscous boundary layer thickness. This explained the observed C-VV backscatter contrast saturation for low viscosity diesel oil at thicknesses greater than 0.15 mm. The model predicted contrast saturation at greater thicknesses for the higher viscosity oils. The data showed this trend but the measurements did not extend to thicknesses which tested the model completely.

  3. Microwave-assisted regeneration of activated carbon.

    PubMed

    Foo, K Y; Hameed, B H

    2012-09-01

    Microwave heating was used in the regeneration of methylene blue-loaded activated carbons produced from fibers (PFAC), empty fruit bunches (EFBAC) and shell (PSAC) of oil palm. The dye-loaded carbons were treated in a modified conventional microwave oven operated at 2450 MHz and irradiation time of 2, 3 and 5 min. The virgin properties of the origin and regenerated activated carbons were characterized by pore structural analysis and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement and determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue (MB). Microwave irradiation preserved the pore structure, original active sites and adsorption capacity of the regenerated activated carbons. The carbon yield and the monolayer adsorption capacities for MB were maintained at 68.35-82.84% and 154.65-195.22 mg/g, even after five adsorption-regeneration cycles. The findings revealed the potential of microwave heating for regeneration of spent activated carbons. PMID:22728787

  4. The science benefits of and the antenna requirements for microwave remote sensing from geostationary orbit

    NASA Technical Reports Server (NTRS)

    Stutzman, Warren L. (Editor); Brown, Gary S. (Editor)

    1991-01-01

    The primary objective of the Large Space Antenna (LSA) Science Panel was to evaluate the science benefits that can be realized with a 25-meter class antenna in a microwave/millimeter wave remote sensing system in geostationary orbit. The panel concluded that a 25-meter or larger antenna in geostationary orbit can serve significant passive remote sensing needs in the 10 to 60 GHz frequency range, including measurements of precipitation, water vapor, atmospheric temperature profile, ocean surface wind speed, oceanic cloud liquid water content, and snow cover. In addition, cloud base height, atmospheric wind profile, and ocean currents can potentially be measured using active sensors with the 25-meter antenna. Other environmental parameters, particularly those that do not require high temporal resolution, are better served by low Earth orbit based sensors.

  5. Convective and stratiform rain: Multichannel microwave sensing over oceans

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Nucciarone, J. J.; Dalu, G.

    1993-01-01

    Measurements made by the Special Sensor Microwave/Imager (SSM/I) radiometer over the oceans, at 19, 37, and 85 GHz in dual polarization, are used to develop a model to classify rain into light-stratiform, moderately convective, and heavy convective types in the mesoscale convective systems (MCS). It is observed that the bulk of the 19- and 37-GHz data are linearly correlated with respect to one another, and generally increase together in brightness as the mean rain rate in the field of view (FOV) of the radiometer increases. However, a significant fraction of the data from these channels departs from this linear relationship, reflecting the nonuniform rain that is convective vs. the relatively light stratiform rain. It is inferred from the SSM/I data, in a MCS, when the slope dT sub 3/dT sub 19 is greater than unity there are optically thin clouds which produce light uniform rain. On the other hand, when dT sub 3/dT sub 19 is close to unity, the rain cells have an open structure and correspond to the convective type of rain. The openings between the cells are apparently a result of the downdrafts and/or entrainment. Relatively low values of 85-GHz brightness temperatures that are present when dT sub 37/dT sub 19 is close to unity support these views and, in addition, leads us to conclude that when the convection is heavy this brightness temperature decreases due to scattering by hydrometeors. On the basis of this explanation of the SSM/I data, an empirical rain retrieval algorithm is developed. Radar backscatter observations over the Atlantic Ocean next to Florida are used to demonstrate the applicability of this method. Three monthly mean maps of rainfall over the oceans from 50 degrees N to 50 degrees S, are presented to illustrate the ability of this method to sense seasonal and interannual variations of rain.

  6. Regionalization of Methane Emissions in the Amazon Basin with Multi-temporal Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Melack, J. M.; Hess, L. L.; Forsberg, B. R.; Hamilton, S. K.; Novo, E. M.

    2002-12-01

    Remote sensing of the Amazon basin with passive and active microwave techniques were applied to determine the temporally varying extent of inundation and associated vegetation, and used in conjunction with field measurements to calculate regional rates of methane emission from wetlands to the atmosphere. Monthly inundation areas were derived from analysis of the 37-GHz polarization difference observed by the Scanning Multichannel Microwave Radiometer (1979 -87) for the mainstem Amazon floodplain in Brazil, the Llanos de Moxos (Beni and Mamore rivers) in Bolivia, the Bananal Island (Araguaia River) and Roraima savannas. Data from the Japanese Earth Resources Satellite-1, L-band synthetic aperture radar were used to determine inundation and wetland vegetation for Amazon basin less than 500 m above sea level at high water (May-June 1996) and low water (October 1995). Although all the measurements of methane emission from aquatic habitats have been performed in the deeply inundated, central basin in open water, flooded forests or floating macrophytes, our basin-wide remote sensing has revealed large areas of seasonally flooded savannas. Therefore, improvements in basin-wide estimates of methane emission will require field studies in wetlands such as those in Bolivia, Roraima and the Bananal.

  7. Microwave sensing of quality attributes of agricultural and food products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microwave sensors for real-time characterization of agricultural and food products have become viable solutions with recent advances in the development of calibration methods and the availability of inexpensive microwave components. The examples shown here for grain, seed, and in-shell peanuts indic...

  8. Comparing land surface phenology derived from satellite and GPS network microwave remote sensing.

    PubMed

    Jones, Matthew O; Kimball, John S; Small, Eric E; Larson, Kristine M

    2014-08-01

    The land surface phenology (LSP) start of season (SOS) metric signals the seasonal onset of vegetation activity, including canopy growth and associated increases in land-atmosphere water, energy and carbon (CO2) exchanges influencing weather and climate variability. The vegetation optical depth (VOD) parameter determined from satellite passive microwave remote sensing provides for global LSP monitoring that is sensitive to changes in vegetation canopy water content and biomass, and insensitive to atmosphere and solar illumination constraints. Direct field measures of canopy water content and biomass changes desired for LSP validation are generally lacking due to the prohibitive costs of maintaining regional monitoring networks. Alternatively, a normalized microwave reflectance index (NMRI) derived from GPS base station measurements is sensitive to daily vegetation water content changes and may provide for effective microwave LSP validation. We compared multiyear (2007-2011) NMRI and satellite VOD records at over 300 GPS sites in North America, and their derived SOS metrics for a subset of 24 homogenous land cover sites to investigate VOD and NMRI correspondence, and potential NMRI utility for LSP validation. Significant correlations (P<0.05) were found at 276 of 305 sites (90.5 %), with generally favorable correspondence in the resulting SOS metrics (r (2)=0.73, P<0.001, RMSE=36.8 days). This study is the first attempt to compare satellite microwave LSP metrics to a GPS network derived reflectance index and highlights both the utility and limitations of the NMRI data for LSP validation, including spatial scale discrepancies between local NMRI measurements and relatively coarse satellite VOD retrievals. PMID:24005849

  9. Is the Wilkins Ice Shelf a Firn Aquifer? Spaceborne Observation of Subsurface Winter Season Liquid Meltwater Storage on the Antarctic Peninsula using Multi-Frequency Active and Passive Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Miller, J.; Scambos, T.; Forster, R. R.; Long, D. G.; Ligtenberg, S.; van den Broeke, M.; Vaughan, D. G.

    2015-12-01

    Near-surface liquid meltwater on ice shelves has been inferred to influence ice shelf stability if it induces hydrofracture and is linked to disintegration events on the Larsen B and the Wilkins ice shelves on the Antarctic Peninsula during the summer months. While the initial Wilkins disintegration event occurred in March of 2009, two smaller disintegration events followed in May and in July of that year. It has long been assumed meltwater refreezes soon after surface melt processes cease. Given this assumption, an earlier hypothesis for the two winter season disintegration events was hydrofracture via a brine infiltration layer. Two lines of evidence supported this hypothesis 1) early airborne radar surveys did not record a reflection from the bottom of the ice shelf, and 2) a shallow core drilled in 1972 on the Wilkins encountered liquid water at a depth of ~7 m. The salinity of the water and the temperature at the base of the core, however, were not described. The recent discovery of winter season liquid meltwater storage on the Greenland ice sheet has changed perceptions on meltwater longevity at depth in firn. Evidence of Greenland's firn aquifer includes liquid meltwater encountered in shallow firn cores at 5 m depth and a lack of reflections from the base of the ice sheet in airborne surveys. Thus, previous lines of evidence suggesting brine infiltration may alternatively suggest the presence of a perennial firn aquifer. We recently demonstrated the capability for observation of Greenland's firn aquifer from space using multi-frequency active and passive microwave remote sensing. This research exploits the retrieval technique developed for Greenland to provide the first spaceborne mappings of winter season liquid meltwater storage on the Wilkins. We combine L-band brightness temperature and backscatter data from the MIRAS instrument (1.4 GHz) aboard ESA's Soil Moisture and Ocean Salinity mission and the radar (1.3 GHZ) and radiometer(1.4 GHz) aboard NASA

  10. Remote sensing of vegetation and soil using microwave ellipsometry

    NASA Technical Reports Server (NTRS)

    Auer, S. O.; Schutt, J. B. (Inventor)

    1977-01-01

    A method is described of determining vegetation height and water content of vegetation from the intensity and state of elliptical polarization of a reflected train of microwaves. The method comprises the steps of reflecting a circularly polarized train of microwaves from vegetation at a predetermined angle of incidence and detecting the reflected train of microwaves. The ratio of the intensities of the electric field vector components is determined, the phase difference of the components is measured, and the refractive index and thickness of the layer of vegetation are computed from a formula. The refractive index is given essentially by the water content of the vegetation.

  11. Laser activated MTOS microwave device

    NASA Technical Reports Server (NTRS)

    Maserjian, J. (Inventor)

    1985-01-01

    A light-activated semiconductor device usable as an optoelectronic switch, pulse generator or optical detector is provided. A semiconductor device is disclosed which provides back-to-back metal-thin oxide-silicon (MTOS) capacitors. Each capacitor includes a thin, light-absorptive aluminum electrode which overlies a thin oxide layer and a lightly doped region implanted in an intrinsic silicon substrate.

  12. An optical fiber sensing technique for temperature distribution measurements in microwave heating

    NASA Astrophysics Data System (ADS)

    Wada, Daichi; Sugiyama, Jun-ichi; Zushi, Hiroaki; Murayama, Hideaki

    2015-08-01

    We introduce an optical fiber sensing technique that can measure the temperature distributions along a fiber during microwave heating. We used a long-length fiber Bragg grating (FBG) as an electromagnetic-immune sensor and interrogated temperature distributions along the FBG by an optical frequency domain reflectometry. Water in a glass tube with a length of 820 mm was heated in a microwave oven, and its temperature distribution along the glass tube was measured using the sensing system. The temperature distribution was obtained in 5 mm intervals. Infrared radiometry was also used to compare the temperature measurement results. Time and spatial variations of the temperature distribution profiles were monitored for several microwave input powers. The results clearly depict inhomogeneous temperature profiles. The applicability and effectiveness of the optical fiber distributed measurement technique in microwave heating are demonstrated.

  13. Peformance evaluation of a passive microwave imaging system. [for remote sensing

    NASA Technical Reports Server (NTRS)

    Mcallum, W. E.

    1973-01-01

    A test program was conducted to evaluate the passive microwave imaging system for possible application in the NASA Earth Resources Program. In addition to test data analysis, the report gives a brief description of the radiometer, its software, and the ground support equipment. The microwave image quality is adequate for remote sensing applications studies. Instrument problems are described, and suggestions are given for possible improvements and potential applications.

  14. A radio picture of the earth. [microwave remote sensing from satellites

    NASA Technical Reports Server (NTRS)

    Webster, W. J., Jr.; Wilheit, T. T.; Chang, T. C.; Gloersen, P.; Schmugge, T. J.

    1975-01-01

    A technique called passive microwave remote sensing can be used to obtain a new view of the planet earth by means of radio telescopes carried aboard artificial satellites. An important relationship between the observed radio brightness temperature and the surface conditions provides the basis for the new technique. A radio image is presented of the entire earth on the basis of Nimbus microwave-image data taken January 12-16, 1973.

  15. Feasibility of microwave interferometry and fourier-transform spectrometry for high-spectral-resolution sensing

    SciTech Connect

    Gerstl, S.; Cooke, B.; Jacobson, A.; Love, S.; Zardecki, A.

    1996-09-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The primary objective of this project was to perform the necessary research and development to determine the feasibility of new ideas that, if successful, could lead to the development of future new programs in high-spectral resolution remote sensing. In active remote sensing systems, the solar illumination of a scene is replaced by a man-made source, preferably a laser beam. However, when laser beams are propagated through a scattering medium, like air, random optical path fluctuations comparable to the optical wavelength are generated giving rise to the speckle effect, which is the most severe perturbation in active remote sensing systems. The limitations introduced by the speckle effect degrade or negate the data interpretation. We sought to introduce better physical models of beam scattering that allow a more realistic simulation environment to be developed that, when applied to experimental data sets, improve their interpretability and increase the information content. Improved beam propagation models require improved knowledge of the spatio-temporal distribution of the scattering and absorbing medium. In the free atmosphere the largest contributor is water vapor in the lower troposphere. We tested the feasibility of using microwave interferometry to measure water-vapor irregularities in the boundary layer. Knowledge of these distributions enable much improved atmospheric correction algorithms for satellite imagery of the earth`s surface to be developed. For hyperspectral active remote sensing systems it is necessary to perform very high-resolution spectral measurements of the reflected laser light. Such measurements are possible with optical interferometers.

  16. Foreword to the Special Issue on the 11th Specialist Meeting on Microwave Radiometry and Remote Sensing Applications (MicroRad 2010)

    NASA Technical Reports Server (NTRS)

    Le Vine, David M; Jackson, Thomas J.; Kim, Edward J.; Lang, Roger H.

    2011-01-01

    The Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment (MicroRad 2010) was held in Washington, DC from March 1 to 4, 2010. The objective of MicroRad 2010 was to provide an open forum to report and discuss recent advances in the field of microwave radiometry, particularly with application to remote sensing of the environment. The meeting was highly successful, with more than 200 registrations representing 48 countries. There were 80 oral presentations and more than 100 posters. MicroRad has become a venue for the microwave radiometry community to present new research results, instrument designs, and applications to an audience that is conversant in these issues. The meeting was divided into 16 sessions (listed in order of presentation): 1) SMOS Mission; 2) Future Passive Microwave Remote Sensing Missions; 3) Theory and Physical Principles of Electromagnetic Models; 4) Field Experiment Results; 5) Soil Moisture and Vegetation; 6) Snow and Cryosphere; 7) Passive/Active Microwave Remote Sensing Synergy; 8) Oceans; 9) Atmospheric Sounding and Assimilation; 10) Clouds and Precipitation; 11) Instruments and Advanced Techniques I; 12) Instruments and Advanced Techniques II; 13) Cross Calibration of Satellite Radiometers; 14) Calibration Theory and Methodology; 15) New Technologies for Microwave Radiometry; 16) Radio Frequency Interference.

  17. Effects of the Ionosphere on Passive Microwave Remote Sensing of Ocean Salinity from Space

    NASA Technical Reports Server (NTRS)

    LeVine, D. M.; Abaham, Saji; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    Among the remote sensing applications currently being considered from space is the measurement of sea surface salinity. The salinity of the open ocean is important for understanding ocean circulation and for modeling energy exchange with the atmosphere. Passive microwave remote sensors operating near 1.4 GHz (L-band) could provide data needed to fill the gap in current coverage and to complement in situ arrays being planned to provide subsurface profiles in the future. However, the dynamic range of the salinity signal in the open ocean is relatively small and propagation effects along the path from surface to sensor must be taken into account. In particular, Faraday rotation and even attenuation/emission in the ionosphere can be important sources of error. The purpose or this work is to estimate the magnitude of these effects in the context of a future remote sensing system in space to measure salinity in L-band. Data will be presented as a function of time location and solar activity using IRI-95 to model the ionosphere. The ionosphere presents two potential sources of error for the measurement of salinity: Rotation of the polarization vector (Faraday rotation) and attenuation/emission. Estimates of the effect of these two phenomena on passive remote sensing over the oceans at L-band (1.4 GHz) are presented.

  18. Investigating Land Surface Phenology Derived from Satellite and GPS Network Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Jones, M. O.; Kimball, J. S.; Small, E. E.; Larson, K. M.

    2013-12-01

    The land surface phenology (LSP) start of season (SOS) metric signals the seasonal onset of vegetation activity, including canopy growth and associated increases in land-atmosphere water, energy and carbon (CO2) exchanges influencing weather and climate variability. The Vegetation Optical Depth (VOD) parameter determined from satellite passive microwave remote sensing provides for global LSP monitoring that is sensitive to changes in vegetation canopy water content and biomass, and insensitive to atmosphere and solar illumination constraints. Direct field measures of canopy water content and biomass changes desired for LSP validation are generally lacking due to prohibitive costs of maintaining regional monitoring networks. Alternatively, a Normalized Microwave Reflectance Index (NMRI) derived from GPS base station measurements is sensitive to daily vegetation water content changes and may provide for effective microwave LSP validation as a relatively high spatial (1000m2) and temporal resolution vegetation phenology measure. We compared NMRI (1.2 and 1.5 GHz) and satellite microwave (AMSR-E sensor) 18.7 GHz frequency VOD records (2007 to 2011) at over 300 GPS sites in North America and their derived SOS metrics for a subset of 24 homogenous land cover sites. Significant correlations were found at 276 of 305 sites, with generally favorable correspondence in the resulting SOS metrics. We also investigated the temporal dynamics of nine NMRI sites within a single 25km resolution VOD pixel and with corresponding 250m MODIS NDVI measures of the three dominant land covers within the pixel to assess the spatial scale discrepancies between these high, moderate, and coarse resolution retrievals. This study is the first attempt to compare satellite microwave LSP metrics to a GPS network derived reflectance index and highlights both the utility and limitations of the NMRI data for LSP validation. Integration of GPS base stations and the NMRI into current phenology observation

  19. Satellite Remote Sensing: Passive-Microwave Measurements of Sea Ice

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Satellite passive-microwave measurements of sea ice have provided global or near-global sea ice data for most of the period since the launch of the Nimbus 5 satellite in December 1972, and have done so with horizontal resolutions on the order of 25-50 km and a frequency of every few days. These data have been used to calculate sea ice concentrations (percent areal coverages), sea ice extents, the length of the sea ice season, sea ice temperatures, and sea ice velocities, and to determine the timing of the seasonal onset of melt as well as aspects of the ice-type composition of the sea ice cover. In each case, the calculations are based on the microwave emission characteristics of sea ice and the important contrasts between the microwave emissions of sea ice and those of the surrounding liquid-water medium.

  20. NASA's Future Active Remote Sensing Missing for Earth Science

    NASA Technical Reports Server (NTRS)

    Hartley, Jonathan B.

    2000-01-01

    Since the beginning of space remote sensing of the earth, there has been a natural progression widening the range of electromagnetic radiation used to sense the earth, and slowly, steadily increasing the spatial, spectral, and radiometric resolution of the measurements. There has also been a somewhat slower trend toward active measurements across the electromagnetic spectrum, motivated in part by increased resolution, but also by the ability to make new measurements. Active microwave instruments have been used to measure ocean topography, to study the land surface. and to study rainfall from space. Future NASA active microwave missions may add detail to the topographical studies, sense soil moisture, and better characterize the cryosphere. Only recently have active optical instruments been flown in space by NASA; however, there are currently several missions in development which will sense the earth with lasers and many more conceptual active optical missions which address the priorities of NASA's earth science program. Missions are under development to investigate the structure of the terrestrial vegetation canopy, to characterize the earth's ice caps, and to study clouds and aerosols. Future NASA missions may measure tropospheric vector winds and make vastly improved measurements of the chemical components of the earth's atmosphere.

  1. Sensing feeble microwave signals via an optomechanical transducer

    NASA Astrophysics Data System (ADS)

    Zhang, Keye; Bariani, Francesco; Dong, Ying; Zhang, Weiping; Meystre, Pierre

    2015-05-01

    Due to their low energy content microwave signals at the single-photon level are extremely challenging to measure. Guided by recent progress in single-photon optomechanics and hybrid optomechanical systems, we propose a multimode optomechanical transducer that can detect intensities significantly below the single-photon level via off-resonant adiabatic transfer of the microwave signal to the optical frequency domain where the measurement is then performed. The influence of intrinsic quantum and thermal fluctuations on the performance of this detector are considered in detail. We acknowledge financial support from National Basic Research Program of China, NSF, ARO and the DARPA QuaSAR and ORCHID programs.

  2. Electrically scanning microwave radiometers. [for satellite-borne remote sensing

    NASA Technical Reports Server (NTRS)

    Mix, R. F.

    1974-01-01

    The electrically scanning microwave radiometer (ESMR) developed for and currently used onboard the Nimbus 5 meteorological satellite is described, along with the ESMR developed for the Nimbus F satellite. They serve for synoptic mapping of microwave emissions from the earth's surface, the instrument on Nimbus 5 measuring these emissions at a wavelength of 1.55 cm (19.35 GHz) and the instrument on Nimbus F, at a wavelength of 0.81 cm (37 GHz). Radiative transfer characteristics measured at these wavelengths are sufficiently different from IR measurements to permit derivation and interpretation of unique meteorological, geomorphological, and oceanographic data.

  3. Cloud-to-Ground Lightning Estimates Derived from SSMI Microwave Remote Sensing and NLDN

    NASA Technical Reports Server (NTRS)

    Winesett, Thomas; Magi, Brian; Cecil, Daniel

    2015-01-01

    Lightning observations are collected using ground-based and satellite-based sensors. The National Lightning Detection Network (NLDN) in the United States uses multiple ground sensors to triangulate the electromagnetic signals created when lightning strikes the Earth's surface. Satellite-based lightning observations have been made from 1998 to present using the Lightning Imaging Sensor (LIS) on the NASA Tropical Rainfall Measuring Mission (TRMM) satellite, and from 1995 to 2000 using the Optical Transient Detector (OTD) on the Microlab-1 satellite. Both LIS and OTD are staring imagers that detect lightning as momentary changes in an optical scene. Passive microwave remote sensing (85 and 37 GHz brightness temperatures) from the TRMM Microwave Imager (TMI) has also been used to quantify characteristics of thunderstorms related to lightning. Each lightning detection system has fundamental limitations. TRMM satellite coverage is limited to the tropics and subtropics between 38 deg N and 38 deg S, so lightning at the higher latitudes of the northern and southern hemispheres is not observed. The detection efficiency of NLDN sensors exceeds 95%, but the sensors are only located in the USA. Even if data from other ground-based lightning sensors (World Wide Lightning Location Network, the European Cooperation for Lightning Detection, and Canadian Lightning Detection Network) were combined with TRMM and NLDN, there would be enormous spatial gaps in present-day coverage of lightning. In addition, a globally-complete time history of observed lightning activity is currently not available either, with network coverage and detection efficiencies varying through the years. Previous research using the TRMM LIS and Microwave Imager (TMI) showed that there is a statistically significant correlation between lightning flash rates and passive microwave brightness temperatures. The physical basis for this correlation emerges because lightning in a thunderstorm occurs where ice is first

  4. Monitoring drought for grassland and cropland using multi-sensor microwave remote sensing data

    NASA Astrophysics Data System (ADS)

    Zhang, A.; Jia, G.

    2012-12-01

    Remote sensing drought indices derived from optical and infrared bands have been successfully used in monitoring drought throughout the world; however the application of microwave remote sensing sensor in drought monitoring has not been thoroughly investigated. In this study, we propose a microwave remote sensing drought index, the Microwave Integrated Drought Index (MIDI), especially for short-term drought monitoring over northern China. The index combined three variables: the Tropical Rainfall Measuring Mission (TRMM) precipitation, land surface temperature (LST) and soil moisture (SM) obtained by the Vrije Universiteit Amsterdam and NASA Goddard Space Flight Center (VUA-NASA) from the Advanced Microwave Scanning Radiometer (AMSR-E) on-board Aqua satellite. The microwave remotely sensed variables were linearly scaled from 0 to 1 for each pixel based on absolute minimum and maximum values for each variable over time, in order to discriminate the weather-related component from the ecosystem component. The microwave indices were evaluated with the Standardized Precipitation Index (SPI), an in-situ meteorological data based drought index. Pearson correlation analyses were performed between the remotely sensed drought indices values and different time scale SPI values for the growing season from 2003 to 2010 to assess the capability of remotely sensed drought indices in monitoring drought over three different climate regions in northern China. There was significant spatial variability in the correlations between remote sensing drought indices and SPI, generally, the Precipitation Condition Index (PCI) showed the highest correlation with 1-month SPI (r around 0.70) whether compared to remote sensing drought indices or different time scale SPI; while correlations between Soil Moisture Condition Index (SMCI), Land Surface Temperature (TCI) and SPI exhibited different trends among three climate regions. The MIDI with proper weights of three components nearly possessed the

  5. Multispectral microwave imaging radar for remote sensing applications

    NASA Technical Reports Server (NTRS)

    Larson, R. W.; Rawson, R.; Ausherman, D.; Bryan, L.; Porcello, L.

    1974-01-01

    A multispectral airborne microwave radar imaging system, capable of obtaining four images simultaneously is described. The system has been successfully demonstrated in several experiments and one example of results obtained, fresh water ice, is given. Consideration of the digitization of the imagery is given and an image digitizing system described briefly. Preliminary results of digitization experiments are included.

  6. Satellite remote sensing of global rainfall using passive microwave radiometry

    SciTech Connect

    Ferriday, J.G.

    1994-12-31

    Global rainfall over land and ocean is estimated using measurements of upwelling microwaves by a satellite passive microwave radiometer. Radiative transfer calculations through a cloud model are used to parameterize an inversion technique for retrieving rain rates from brightness temperatures measured by the Special Sensor Microwave Imager (SSM/I). The rainfall retrieval technique is based on the interaction between multi-spectral microwave radiances and millimeter sized liquid and frozen hydrometeors distributed in the satellite`s field of view. The rain rate algorithm is sensitive to both hydrometeor emission and scattering while being relatively insensitive to extraneous atmospheric and surface effects. Separate formulations are used over ocean and land to account for different background microwave characteristics and the algorithm corrects for inhomogeneous distributions of rain rates within the satellite`s field of view. Estimates of instantaneous and climate scale rainfall are validated through comparisons with modeled clouds, surface radars, rain gauges and alternative satellite estimates. The accuracy of the rainfall estimates is determined from a combination of validation comparisons, theoretical sampling error calculations, and modeled sensitivity to variations in atmospheric and surface radiative properties. An error budget is constructed for both instantaneous rain rates and climate scale global estimates. At a one degree resolution, the root mean square errors in instantaneous rain rate estimates are 13% over ocean and 20% over land. The root mean square errors in global rainfall totals over a four month period are found to be 46% over ocean and 63% over land. Global rainfall totals are computed on a monthly scale for a three year period from 1987 to 1990. The time series is analyzed for climate scale rainfall distribution and variability.

  7. Hydrazine sensing properties of microwave synthesized graphene/ZnO composites

    NASA Astrophysics Data System (ADS)

    Sreejesh, M.; Nagaraja, H. S.; Udaya Bhat, K.

    2016-05-01

    This paper reports the synthesis of graphene/ ZnO nanocomposite using microwave method and its application in sensing of hydrazine. The morphological characteristics of the samples are studied using Scanning Electron Microscope (SEM). The formation of the composite is further confirmed by the X-ray Diffraction (XRD). Energy Dispersive X-ray Analysis (EDAX) shows the presence of carbon indicating the presence of graphene. The hydrazine sensing property of the electrode is studied using cyclic voltammometry (CV) and Chronoamperometry (CA) studeis.

  8. Microwave Sensing of Density and Moisture in Granular Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The importance of moisture measurement in grain and seed is discussed, and a brief history of the development of moisture sensing instruments, based on sensing of dielectric properties of these materials, is presented. Data are presented graphically on the permittivities or dielectric properties of...

  9. Normal-pressure microwave rapid synthesis of hierarchical SnO2@rGO nanostructures with superhigh surface areas as high-quality gas-sensing and electrochemical active materials

    NASA Astrophysics Data System (ADS)

    Yin, Li; Chen, Deliang; Cui, Xue; Ge, Lianfang; Yang, Jing; Yu, Lanlan; Zhang, Bing; Zhang, Rui; Shao, Guosheng

    2014-10-01

    Hierarchical SnO2@rGO nanostructures with superhigh surface areas are synthesized via a simple redox reaction between Sn2+ ions and graphene oxide (GO) nanosheets under microwave irradiation. XRD, SEM, TEM, XPS, TG-DTA and N2 adsorption-desorption are used to characterize the compositions and microstructures of the SnO2@rGO samples obtained. The SnO2@rGO nanostructures are used as gas-sensing and electroactive materials to evaluate their property-microstructure relationship. The results show that SnO2 nanoparticles (NPs) with particle sizes of 3-5 nm are uniformly anchored on the surfaces of reduced graphene oxide (rGO) nanosheets through a heteronucleation and growth process. The as-obtained SnO2@rGO sample with a hierarchically sesame cake-like microstructure and a superhigh specific surface area of 2110.9 m2 g-1 consists of 92 mass% SnO2 NPs and ~8 mass% rGO nanosheets. The sensitivity of the SnO2@rGO sensor upon exposure to 10 ppm H2S is up to 78 at the optimal operating temperature of 100 °C, and its response time is as short as 7 s. Compared with SnO2 nanocrystals (5-10 nm), the hierarchical SnO2@rGO nanostructures have enhanced gas-sensing behaviors (i.e., high sensitivity, rapid response and good selectivity). The SnO2@rGO nanostructures also show excellent electroactivity in detecting sunset yellow (SY) in 0.1 M phosphate buffer solution (pH = 2.0). The enhancement in gas-sensing and electroactive performance is mainly attributed to the unique hierarchical microstructure, high surface areas and the synergistic effect of SnO2 NPs and rGO nanosheets.

  10. Modeling the use of microwave energy in sensing of moisture content in vidalia onions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microwave moisture sensing provides a means to nondestructively determine the amount of water in materials. This is accomplished through the correlation of dielectric constant and loss factor with moisture content in the material. In this study, linear relationships between a density-independent fun...

  11. Practical Microwave Meter for Sensing Moisture and Density in Granular Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A low-cost microwave sensor for rapid and nondestructive sensing of bulk density and moisture content in granular and particulate materials has been built and tested. The sensor was made with inexpensive, off-the-shelf components and operates at 5.8 GHz. Three permittivity-based algorithms were us...

  12. IRIS - A concept for microwave sensing of soil moisture and ocean salinity

    NASA Technical Reports Server (NTRS)

    Moghaddam, M.; Njoku, E.

    1997-01-01

    A concept is described for passive microwave sensing of soil moisture and ocean salinity from space. The Inflatable Radiometric Imaging System (IRIS) makes use of a large-diameter, offset-fed, parabolic-torus antenna with multiple feeds, in a conical pushbroom configuration.

  13. Microwave assisted reconstruction of optical interferograms for distributed fiber optic sensing.

    PubMed

    Huang, Jie; Hua, Lei; Lan, Xinwei; Wei, Tao; Xiao, Hai

    2013-07-29

    This paper reports a distributed fiber optic sensing technique through microwave assisted separation and reconstruction of optical interferograms in spectrum domain. The approach involves sending a microwave-modulated optical signal through cascaded fiber optic interferometers. The microwave signal was used to resolve the position and reflectivity of each sensor along the optical fiber. By sweeping the optical wavelength and detecting the modulation signal, the optical spectrum of each sensor can be reconstructed. Three cascaded fiber optic extrinsic Fabry-Perot interferometric sensors were used to prove the concept. Their microwave-reconstructed interferogram matched well with those recorded individually using an optical spectrum analyzer. The application in distributed strain measurement has also been demonstrated. PMID:23938685

  14. Effects of corn stalk orientation and water content on passive microwave sensing of soil moisture

    NASA Technical Reports Server (NTRS)

    Oneill, P. E.; Blanchard, B. J.; Wang, J. R.; Gould, W. I.; Jackson, T. J.

    1984-01-01

    A field experiment was conducted utilizing artificial arrangements of plant components during the summer of 1982 to examine the effects of corn canopy structure and plant water content on microwave emission. Truck-mounted microwave radiometers at C (5 GHz) and L (1.4 GHz) band sensed vertically and horizontally polarized radiation concurrent with ground observations of soil moisture and vegetation parameters. Results indicate that the orientation of cut stalks and the distribution of their dielectric properties through the canopy layer can influence the microwave emission measured from a vegetation/soil scene. The magnitude of this effect varies with polarization and frequency and with the amount of water in the plant, disappearing at low levels of vegetation water content. Although many of the canopy structures and orientations studied in this experiment are somewhat artificial, they serve to improve understanding of microwave energy interactions within a vegetation canopy and to aid in the development of appropriate physically based vegetation models.

  15. Passive microwave remote sensing for sea ice research

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Techniques for gathering data by remote sensors on satellites utilized for sea ice research are summarized. Measurement of brightness temperatures by a passive microwave imager converted to maps of total sea ice concentration and to the areal fractions covered by first year and multiyear ice are described. Several ancillary observations, especially by means of automatic data buoys and submarines equipped with upward looking sonars, are needed to improve the validation and interpretation of satellite data. The design and performance characteristics of the Navy's Special Sensor Microwave Imager, expected to be in orbit in late 1985, are described. It is recommended that data from that instrument be processed to a form suitable for research applications and archived in a readily accessible form. The sea ice data products required for research purposes are described and recommendations for their archival and distribution to the scientific community are presented.

  16. Microwave remote sensing measurements of oil pollution on the ocean

    NASA Technical Reports Server (NTRS)

    Croswell, W. F.; Blume, H.-J. C.; Johnson, J. W.

    1981-01-01

    Microwave and optical remote sensors were flown over fresh and weathered crude oil released from a surface research vessel and also over a slick formed on the sea by frozen oleyl alcohol cubes released from a helicopter. For the crude oil experiments, microwave radiometric measurements at 1.43, 2.65, 22, and 31 GHz are reported, along with the variable incidence angle scattering measurements at 13.9 GHz. For these experiments, unusual depressions in the L-band brightness temperature were observed, possibly related to dispersants applied to the crude oil. Similar depressions, but with much larger values, were observed over the oleyl alcohol monomolecular slicks. Images obtained at 31 and 22 GHz were used to infer oil volume, yielding values which bound the known amounts spilled. Ku band measurements obtained in repeated passes over crude oil slicks are also discussed.

  17. Remote Strain Sensing of CFRP Using Microwave Frequency Domain Reflectometry

    NASA Technical Reports Server (NTRS)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    NASA's Advanced Composites Project is investigating technologies that increase automated remote inspection of aircraft composite structures. Therefore, microwave Frequency Domain Reflectometry (FDR) is being investigated as a method of enabling rapid remote measurement of strain occurring at the first ply of a composite fiber reinforced polymer (CFRP) structure using Radio Frequency (RF) Electro-Magnetic (EM) radiation. While microwave reflectometry has been used to detect disbonds in CFRP structures, its use in detecting strain has been limited. This work will present data demonstrating the measurement of the reactance changes due to loading conditions that are indicative of strain in a CFRP structure. In addition, the basic EM signature will be presented along with an analysis of temperature and humidity effects.

  18. Wide dynamic range microwave planar coupled ring resonator for sensing applications

    NASA Astrophysics Data System (ADS)

    Zarifi, Mohammad Hossein; Daneshmand, Mojgan

    2016-06-01

    A highly sensitive, microwave-coupled ring resonator with a wide dynamic range is studied for use in sensing applications. The resonator's structure has two resonant rings and, consequently, two resonant frequencies, operating at 2.3 and 2.45 GHz. Inductive and capacitive coupling mechanisms are explored and compared to study their sensing performance. Primary finite element analysis and measurement results are used to compare the capacitive and inductive coupled ring resonators, demonstrating sensitivity improvements of up to 75% and dynamic range enhancement up to 100% in the capacitive coupled structure. In this work, we are proposing capacitive coupled planar ring resonators as a wide dynamic range sensing platform for liquid sensing applications. This sensing device is well suited for low-cost, real-time low-power, and CMOS compatible sensing technologies.

  19. Monolithic microwave integrated circuit devices for active array antennas

    NASA Technical Reports Server (NTRS)

    Mittra, R.

    1984-01-01

    Two different aspects of active antenna array design were investigated. The transition between monolithic microwave integrated circuits and rectangular waveguides was studied along with crosstalk in multiconductor transmission lines. The boundary value problem associated with a discontinuity in a microstrip line is formulated. This entailed, as a first step, the derivation of the propagating as well as evanescent modes of a microstrip line. The solution is derived to a simple discontinuity problem: change in width of the center strip. As for the multiconductor transmission line problem. A computer algorithm was developed for computing the crosstalk noise from the signal to the sense lines. The computation is based on the assumption that these lines are terminated in passive loads.

  20. An intercomparison of available soil moisture estimates from thermal-infrared and passive microwave remote sensing and land-surface modeling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Remotely-sensed soil moisture studies have mainly focused on retrievals using active and passive microwave (MW) sensors whose measurements provided a direct relationship to soil moisture (SM). MW sensors present obvious advantages such as the ability to retrieve through non-precipitating cloud cover...

  1. Proposed Definitions of Some Technical Terms Frequently Used in Microwave Radiometry for Remote Sensing

    NASA Technical Reports Server (NTRS)

    Shiue, James C.; Zukor, Dorothy J. (Technical Monitor)

    2000-01-01

    The use of microwave radiometry for remote sensing is a relatively young field. As a result, there are no standard definitions of many frequently used technical terms; a lot of which are conventional usages carried-over from optical remote sensing, and a lot more are shared with electrical or microwave engineering. Sometimes the divergent notions and assumptions originating from a different field may cause ambiguity or confusions. It is proposed that we establish a list of frequently used terms, together with their 'standard' definitions and hope that they will gradually gain general acceptance by the remote sensing community. It would be even more useful if the IEEE community can set up a standard committee of sort to develop and maintain the standards. To minimize the effort, the existing terms should be kept or reinterpreted as much as possible. For example, the term 'Instantaneous Field of View' (IFOV), originally coming from the optical remote sensing field, is now appearing in microwave remote sensing literature frequently. The IFOV refers to the 'beam width' or the 'diameter' of the beam's geometrical projection on earth surface. Since the definition of 'beam width' is different for an optical system versus a microwave antenna, the use of IFOV in microwave radiometry needed to be clarified. Also, the meaning of the IFOV will be different depending upon whether the beam is scanning or not, and how the scanning takes place, e.g. 'continuous scanning' vs 'stare-and-step scan.' From this one term alone, it is clear that more subtle meanings must be spell out in detail and a 'standard' definition would help in understanding and comparing systems and data in the literature. A selected list of terms with their suggested definitions will be discussed in this presentation.

  2. New Small Satellite Capabilities for Microwave Atmospheric Remote Sensing: The Earth Observing Nanosatellite-Microwave (EON-MW)

    NASA Astrophysics Data System (ADS)

    Blackwell, W. J.

    2015-12-01

    Four nanosatellite advanced technology missions flying microwave radiometers for high-resolution atmospheric sensing are in varying stages of development. Microwave instrumentation is particularly well suited for implementation on a very small satellite, as the sensor requirements for power, pointing, and spatial resolution (aperture size) can be accommodated by a nanosatellite platform. The first mission, the Microsized Microwave Atmospheric Satellite (MicroMAS), was developed to demonstrate temperature sounding in nine channels near 118 GHz on a 3U CubeSat (10x10x34 cm; 4.25 kg). MicroMAS was recently released from the International Space Station (ISS) for a 100-day mission, and while an eventual transmitter failure prevented demonstration of the radiometer payload, all key spacecraft subsystems provided on-orbit data to validate performance. Two 3U CubeSat follow-on missions, MicroMAS-2 (12 channels near 90, 118, 183, and 206 GHz; cross-track scanning) and MiRaTA (12 channels near 60, 183, and 206 GHz; no scanning; GPSRO onboard), will launch in 2016 for further demonstration. Building upon this work, the Earth Observing Nanosatellite-Microwave mission is being formulated by MIT Lincoln Laboratory for the NOAA National Environmental Satellite, Data, and Information Service as part of the Polar Follow-On (PFO) budget request to extend JPSS for two more missions, and provides a means to mitigate the risk of a gap in continuity of weather observations. The PFO request aims to achieve robustness in the polar satellite system to ensure continuity of NOAA's polar weather observations. The baseline EON-MW design accommodates a scanning 22-channel high-resolution microwave spectrometer on a 12U (22x22x34 cm, 20 kg) CubeSat platform to provide data continuity with the existing AMSU and ATMS microwave sounding systems. EON-MW will nominally be launched into a sun-synchronous orbit for a two to three year mitigation mission in 2019 that will also extend technology

  3. Stereological characterization of dry alpine snow for microwave remote sensing

    NASA Technical Reports Server (NTRS)

    Davis, Robert E.; Dozier, Jeff

    1989-01-01

    A persistent problem in investigations of electromagnetic properties of snow, from reflectance at visible wavelengths to emission and backscattering in the microwave, has been the proper characterization of the snow's physical properties. It is suggested that the granular and laminar structure of snow can be measured in its aggregated state by stereology performed on sections prepared from snow specimens, and that these kinds of measurements can be incorporated into models of the electromagnetic properties. With careful sampling, anisotropy in the snow microstructure at various scales can be quantified. It is shown how stereological parameters can be averaged over orientation and optical depth for radiative transfer modeling.

  4. Active microwave responses - An aid in improved crop classification

    NASA Technical Reports Server (NTRS)

    Rosenthal, W. D.; Blanchard, B. J.

    1984-01-01

    A study determined the feasibility of using visible, infrared, and active microwave data to classify agricultural crops such as corn, sorghum, alfalfa, wheat stubble, millet, shortgrass pasture and bare soil. Visible through microwave data were collected by instruments on board the NASA C-130 aircraft over 40 agricultural fields near Guymon, OK in 1978 and Dalhart, TX in 1980. Results from stepwise and discriminant analysis techniques indicated 4.75 GHz, 1.6 GHz, and 0.4 GHz cross-polarized microwave frequencies were the microwave frequencies most sensitive to crop type differences. Inclusion of microwave data in visible and infrared classification models improved classification accuracy from 73 percent to 92 percent. Despite the results, further studies are needed during different growth stages to validate the visible, infrared, and active microwave responses to vegetation.

  5. Active microwave remote sensing research program plan. Recommendations of the Earth Resources Synthetic Aperture Radar Task Force. [application areas: vegetation canopies, surface water, surface morphology, rocks and soils, and man-made structures

    NASA Technical Reports Server (NTRS)

    1980-01-01

    A research program plan developed by the Office of Space and Terrestrial Applications to provide guidelines for a concentrated effort to improve the understanding of the measurement capabilities of active microwave imaging sensors, and to define the role of such sensors in future Earth observations programs is outlined. The focus of the planned activities is on renewable and non-renewable resources. Five general application areas are addressed: (1) vegetation canopies, (2) surface water, (3) surface morphology, (4) rocks and soils, and (5) man-made structures. Research tasks are described which, when accomplished, will clearly establish the measurement capabilities in each area, and provide the theoretical and empirical results needed to specify and justify satellite systems using imaging radar sensors for global observations.

  6. Microwave remote sensing and its application to soil moisture detection

    NASA Technical Reports Server (NTRS)

    Newton, R. W. (Principal Investigator)

    1977-01-01

    The author has identified the following significant results. Experimental measurements were utilized to demonstrate a procedure for estimating soil moisture, using a passive microwave sensor. The investigation showed that 1.4 GHz and 10.6 GHz can be used to estimate the average soil moisture within two depths; however, it appeared that a frequency less than 10.6 GHz would be preferable for the surface measurement. Average soil moisture within two depths would provide information on the slope of the soil moisture gradient near the surface. Measurements showed that a uniform surface roughness similar to flat tilled fields reduced the sensitivity of the microwave emission to soil moisture changes. Assuming that the surface roughness was known, the approximate soil moisture estimation accuracy at 1.4 GHz calculated for a 25% average soil moisture and an 80% degree of confidence, was +3% and -6% for a smooth bare surface, +4% and -5% for a medium rough surface, and +5.5% and -6% for a rough surface.

  7. Validating a Satellite Microwave Remote Sensing Based Global Record of Daily Landscape Freeze-Thaw Dynamics

    NASA Astrophysics Data System (ADS)

    Kimball, J. S.; Kim, Y.; McDonald, K. C.

    2012-12-01

    The freeze-thaw (FT) parameter from satellite microwave remote sensing quantifies the predominant landscape frozen or thawed state and is closely linked to surface energy budget and hydrologic activity, vegetation growth, terrestrial carbon budgets and land-atmosphere trace gas exchange. A global Earth System Data Record of daily landscape FT status (FT-ESDR) was developed using a temporal change classification of overlapping 37 GHz brightness temperature (Tb) series from the Scanning Multichannel Microwave Radiometer (SMMR) and Special Sensor Microwave Imager (SSM/I), and encompassing land areas where seasonal frozen temperatures influence ecosystem processes. A temporally consistent, long-term (>30 yr) FT record was created by ensuring cross-sensor consistency through pixel-wise adjustment of the SMMR Tb record based on empirical analyses of overlapping SMMR and SSM/I measurements. The FT-ESDR is designed to determine the FT status of the composite landscape vegetation-snow-soil medium with sufficient accuracy to characterize frozen temperature constraints to surface water mobility, vegetation productivity and land-atmosphere CO2 fluxes. A multi-tier validation scheme was applied using in situ temperature measurements, other satellite FT retrievals and synergistic biophysical data. These results are incorporated into the product metadata structure, including mean daily spatial classification accuracies and annual quality assessment (QA) maps accounting for landscape heterogeneity, algorithm limitations and sensor retrieval gaps. The resulting FT-ESDR shows mean annual spatial classification accuracies of 91 (+/-8.6) and 84 (+/-9.3) percent for PM and AM overpass retrievals. Accuracy is reduced during seasonal transition periods when FT heterogeneity is maximized within the relatively coarse (~25-km) satellite footprint. The QA rankings range from low (estimated accuracy <70%) to best (>90%) categories; mean annual QA results for the 1979-2011 period show relative

  8. Estimation of Snow Parameters Based on Passive Microwave Remote Sensing and Meteorological Information

    NASA Technical Reports Server (NTRS)

    Tsang, Leung; Hwang, Jenq-Neng

    1996-01-01

    A method to incorporate passive microwave remote sensing measurements within a spatially distributed snow hydrology model to provide estimates of the spatial distribution of Snow Water Equivalent (SWE) as a function of time is implemented. The passive microwave remote sensing measurements are at 25 km resolution. However, in mountain regions the spatial variability of SWE over a 25 km footprint is large due to topographic influences. On the other hand, the snow hydrology model has built-in topographic information and the capability to estimate SWE at a 1 km resolution. In our work, the snow hydrology SWE estimates are updated and corrected using SSM/I passive microwave remote sensing measurements. The method is applied to the Upper Rio Grande River Basin in the mountains of Colorado. The change in prediction of SWE from hydrology modeling with and without updating is compared with measurements from two SNOTEL sites in and near the basin. The results indicate that the method incorporating the remote sensing measurements into the hydrology model is able to more closely estimate the temporal evolution of the measured values of SWE as a function of time.

  9. Microwave sensing for meat and fish structure evaluation

    NASA Astrophysics Data System (ADS)

    Clerjon, S.; Damez, J. L.

    2007-04-01

    Monitoring changes in muscle structure during the ageing of bovine meat and quality loss due to fish freezing are major industrial challenges. During ageing, bovine muscle becomes tender through muscle fibre deterioration, and full control of this process is essential. Conversely, degradation of fish muscle, often due to long storage or a freezing cycle, lowers quality. To improve competitiveness, and to respond to consumer quality demand, muscle structure needs to be evaluated in-line. We present here a polarimetric microwave method (10-24 GHz) consisting in free space and contact reflection coefficient measurements using a horn antenna and rectangular probes, respectively. This method is based on the measurement of dielectric properties of tissues parallel and perpendicular to muscle fibre directions. The dielectric properties of structured tissues such as muscles are anisotropic, but during processing structural disorganization reduces this anisotropy. The method is illustrated by the discrimination of fresh and frozen-thawed fish fillets and by monitoring of meat ageing.

  10. Microwave spectroscopy of the active sun

    NASA Technical Reports Server (NTRS)

    Hurford, Gordon

    1992-01-01

    In studies of solar active regions and bursts, the ability to obtain spatially resolved radio spectra (brightness temperature spectra) opens a whole new range of possibilities for study of the solar corona. For active regions, two-dimensional maps of brightness temperature over a wide range of frequencies allows one to determine temperature, column density, and magnetic field strength over the entire region in a straightforward, unambiguous way. For flares, the time-dependent electron energy distribution, number of accelerated electrons, and magnetic field strength and direction can be found. In practice, obtaining complete radio images at a large number of frequencies is a significant technical challenge, especially while keeping costs down. Our instrument at Owens Valley Radio Observatory provided the starting point for a modest attempt at meeting this goal. We proposed to build three additional, very low-cost 2-m antennas which, when combined with our existing two 27-m dishes, expands the array to 5 elements. This modest increase in number of solar dedicated antennas, from 2 to 5, increases our maximum number of physical baselines from 1 to 10 and allows the instrument to do true imaging of solar microwave sources, both bursts and active regions. Combined with the technique of frequency synthesis, the new array has up to 450 effective baselines, giving imaging capability that approaches that of a sub-arrayed VLA. The prototype antenna design was finalized and the antenna was put into operation in Nov. 1989.

  11. Active microwave computed brain tomography: the response to a challenge.

    PubMed

    Almirall, H; Broquetas, A; Jofre, L

    1991-02-01

    The potential application of active microwave techniques to brain imaging is studied by numerical simulations and experimentally using a recently developed cylindrical microwave scanner. The potential advantages and limitations of this method in static and dynamic brain imaging are presented and compared with other imaging techniques. PMID:2062119

  12. Development of Si(1-x)Ge(x) technology for microwave sensing applications

    NASA Technical Reports Server (NTRS)

    Mena, Rafael A.; Taub, Susan R.; Alterovitz, Samuel A.; Young, Paul E.; Simons, Rainee N.; Rosenfeld, David

    1993-01-01

    The progress for the first year of the work done under the Director's Discretionary Fund (DDF) research project entitled, 'Development of Si(1-x)Ge(x) Technology for Microwave Sensing Applications.' This project includes basic material characterization studies of silicon-germanium (SiGe), device processing on both silicon (Si) and SiGe substrates, and microwave characterization of transmission lines on silicon substrates. The material characterization studies consisted of ellipsometric and magneto-transport measurements and theoretical calculations of the SiGe band-structure. The device fabrication efforts consisted of establishing SiGe device processing capabilities in the Lewis cleanroom. The characterization of microwave transmission lines included studying the losses of various coplanar transmission lines and the development of transitions on silicon. Each part of the project is discussed individually and the findings for each part are presented. Future directions are also discussed.

  13. Microwave interrogated large core fused silica fiber Michelson interferometer for strain sensing.

    PubMed

    Hua, Liwei; Song, Yang; Huang, Jie; Lan, Xinwei; Li, Yanjun; Xiao, Hai

    2015-08-20

    A Michelson-type large core optical fiber sensor has been developed, which is designed based on the optical carrier-based microwave interferometry technique, and fabricated by using two pieces of 200-μm diameter fused silica core fiber as two arms of the Michelson interferometer. The interference fringe pattern caused by the optical path difference of the two arms is interrogated in the microwave domain, where the fringe visibility of 40 dB has easily been obtained. The strain sensing at both room temperature and high temperatures has been demonstrated by using such a sensor. Experimental results show that this sensor has a linear response to the applied strain, and also has relatively low temperature-strain cross talk. The dopant-free quality of the fused silica fiber provides high possibility for the sensor to have promising strain sensing performance in a high temperature environment. PMID:26368751

  14. Characterization of vegetation by microwave and optical remote sensing

    NASA Technical Reports Server (NTRS)

    Daughtry, C. S. T. (Principal Investigator); Ranson, K. J.; Biehl, L. L.

    1986-01-01

    Two series of carefully controlled experiments were conducted. First, plots of important crops (corn, soybeans, and sorghum), prairie grasses (big bluestem, switchgrass, tal fescue, orchardgrass, bromegrass), and forage legumes (alfalfa, red clover, and crown vetch) were manipulated to produce wide ranges of phytomass, leaf area index, and canopy architecture. Second, coniferous forest canopies were simulated using small balsam fir trees grown in large pots of soil and arranged systematically on a large (5 m) platform. Rotating the platform produced many new canopies for frequency and spatial averaging of the backscatter signal. In both series of experiments, backscatter of 5.0 GHz (C-Band) was measured as a function of view angle and polarization. Biophysical measurements included leaf area index, fresh and dry phytomass, water content of canopy elements, canopy height, and soil roughness and moisture content. For a subset of the above plots, additional measurements were acquired to exercise microwave backscatter models. These measurements included size and shape of leaves, stems, and fruit and the probability density function of leaf and stem angles. The relationships of the backscattering coefficients and the biophysical properties of the canopies were evaluated using statistical correlations, analysis of variance, and regression analysis. Results from the corn density and balsam fir experiments are discussed and analyses of data from the other experiments are summarized.

  15. Discrimination of soil hydraulic properties by combined thermal infrared and microwave remote sensing

    NASA Technical Reports Server (NTRS)

    Vandegriend, A. A.; Oneill, P. E.

    1986-01-01

    Using the De Vries models for thermal conductivity and heat capacity, thermal inertia was determined as a function of soil moisture for 12 classes of soil types ranging from sand to clay. A coupled heat and moisture balance model was used to describe the thermal behavior of the top soil, while microwave remote sensing was used to estimate the soil moisture content of the same top soil. Soil hydraulic parameters are found to be very highly correlated with the combination of soil moisture content and thermal inertia at the same moisture content. Therefore, a remotely sensed estimate of the thermal behavior of the soil from diurnal soil temperature observations and an independent remotely sensed estimate of soil moisture content gives the possibility of estimating soil hydraulic properties by remote sensing.

  16. Future Challenges for Microwave Remote Sensing in Support of Earth Sciences

    NASA Technical Reports Server (NTRS)

    Hildebrand, Peter H.; Zukor, Dorothy J. (Technical Monitor)

    2000-01-01

    The presentation will include an overview of leading Earth Science scientific problems that can be addressed using microwave remote sensing, including soil moisture, precipitation, sea salinity, sea surface winds, atmospheric profiling, etc. Using this basis of scientific measurement, the presentation will outline current technological impediments to implementing new measurement system, concentrating on a few example approaches to new technology, such as the conceptual design tradeoffs and capability improvements represented by a fleet of inexpensive nano-satellites, versus geostationary large aperture sensing systems. The outlook for measurement capabilities will be traded against the expected technological hurdles.

  17. A cross beam interferometer radiometer for high resolution microwave sensing

    NASA Astrophysics Data System (ADS)

    Malliot, Harold A.

    The conceptual design of a cross beam interferometer radiometer (CBIR) for sea surface temperature sensing at 5.0 GHz is described. In a 833-km orbit, the radiometer provides 0.48 K sensitivity with a spatial resolution less than 25 km in a 1561-km swath. The radiometer consists of a pair of rectangular phased arrays in a T configuration. Each array forms ten colinear beams that project ten pairs of crossed elliptical footprints on the sea surface. The footprints from the horizontal array have minor axes that range from 14.6 km to 22.9 km and are oriented in the cross-track direction. The footprints from the vertical array have minor axes that range from 18.6 km to 25.0 km and are oriented in the along-track direction. The Mills periodic 0-180-deg switching radio telescope technique is used to sense the variations in sea surface radio-thermal brightness temperature in the coincidence areas where the beams overlap. The CBIR concept, system design approach, antenna design and beamforming technique are described.

  18. Brazil's remote sensing activities in the Eighties

    NASA Technical Reports Server (NTRS)

    Raupp, M. A.; Pereiradacunha, R.; Novaes, R. A.

    1985-01-01

    Most of the remote sensing activities in Brazil have been conducted by the Institute for Space Research (INPE). This report describes briefly INPE's activities in remote sensing in the last years. INPE has been engaged in research (e.g., radiance studies), development (e.g., CCD-scanners, image processing devices) and applications (e.g., crop survey, land use, mineral resources, etc.) of remote sensing. INPE is also responsible for the operation (data reception and processing) of the LANDSATs and meteorological satellites. Data acquisition activities include the development of CCD-Camera to be deployed on board the space shuttle and the construction of a remote sensing satellite.

  19. On the Opportunities and Challenges in Microwave Medical Sensing and Imaging.

    PubMed

    Chandra, Rohit; Zhou, Huiyuan; Balasingham, Ilangko; Narayanan, Ram M

    2015-07-01

    Widely used medical imaging systems in clinics currently rely on X-rays, magnetic resonance imaging, ultrasound, computed tomography, and positron emission tomography. The aforementioned technologies provide clinical data with a variety of resolution, implementation cost, and use complexity, where some of them rely on ionizing radiation. Microwave sensing and imaging (MSI) is an alternative method based on nonionizing electromagnetic (EM) signals operating over the frequency range covering hundreds of megahertz to tens of gigahertz. The advantages of using EM signals are low health risk, low cost implementation, low operational cost, ease of use, and user friendliness. Advancements made in microelectronics, material science, and embedded systems make it possible for miniaturization and integration into portable, handheld, mobile devices with networking capability. MSI has been used for tumor detection, blood clot/stroke detection, heart imaging, bone imaging, cancer detection, and localization of in-body RF sources. The fundamental notion of MSI is that it exploits the tissue-dependent dielectric contrast to reconstruct signals and images using radar-based or tomographic imaging techniques. This paper presents a comprehensive overview of the active MSI for various medical applications, for which the motivation, challenges, possible solutions, and future directions are discussed. PMID:25993698

  20. A summary of microwave remote sensing investigations planned for BOREAS

    NASA Technical Reports Server (NTRS)

    Mcdonald, Kyle C.

    1993-01-01

    The Boreal Ecosystem - Atmosphere Study (BOREAS) is a multidisciplinary field and remote sensing study that will be implemented jointly by the United States and Canada. The goal of BOREAS is to obtain an improved understanding of the interactions between the boreal forest biome and the atmosphere in order to clarify their roles in global change. Specific objectives are to improve the understanding of the processes that govern the exchanges of water, energy, heat, carbon, and trace gases between boreal ecosystems and the atmosphere, and to develop and validate remote sensing algorithms for transferring the understanding of these processes from local to regional scales. Two principal field sites, both within Canada, were selected. The northern site is located near Thompson, Manitoba, and the southern site encompasses Prince Albert National Park in Saskatchewan. The growing season in the northern site tends to be limited by growing-degree days while the southern site is limited by soil moisture and fire frequency. Most of the field work will occur at these two sites during 1993 and 1994 as part of six field campaigns. The first of these campaigns is scheduled for August 1993 and will involve instrument installation and an operational shakedown. Three large scale Intensive Field Campaigns (IFC's) are scheduled for 1994, along with two smaller scale Focused Field Campaigns (FFC's). The first 1994 campaign will be an FFC designed to capture the biome under completely frozen conditions during the winter. The second FFC and the first IFC are scheduled to capture the spring thaw period. Another IFC will take place in the summer during a period of maximum water stress. Finally, the third FFC will be scheduled to capture the collapse into senescence during the fall.

  1. Solar Activity Studies using Microwave Imaging Observations

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.

    2016-01-01

    We report on the status of solar cycle 24 based on polar prominence eruptions (PEs) and microwave brightness enhancement (MBE) information obtained by the Nobeyama radioheliograph. The north polar region of the Sun had near-zero field strength for more than three years (2012-2015) and ended only in September 2015 as indicated by the presence of polar PEs and the lack of MBE. The zero-polar-field condition in the south started only around 2013, but it ended by June 2014. Thus the asymmetry in the times of polarity reversal switched between cycle 23 and 24. The polar MBE is a good proxy for the polar magnetic field strength as indicated by the high degree of correlation between the two. The cross-correlation between the high- and low-latitude MBEs is significant for a lag of approximately 5.5 to 7.3 years, suggesting that the polar field of one cycle indicates the sunspot number of the next cycle in agreement with the Babcock-Leighton mechanism of solar cycles. The extended period of near-zero field in the north-polar region should result in a weak and delayed sunspot activity in the northern hemisphere in cycle 25.

  2. Sea surface signature of tropical cyclones using microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Kil, Bumjun; Burrage, Derek; Wesson, Joel; Howden, Stephan

    2013-06-01

    Measuring the sea surface during tropical cyclones (TC) is challenging due to severe weather conditions that prevent shipboard measurements and clouds which mask the sea surface for visible satellite sensors. However, sea surface emission in the microwave L-band can penetrate rain and clouds and be measured from space. The European Space Agency (ESA) MIRAS L-band radiometer on the Soil Moisture and Ocean Salinity (SMOS) satellite enables a view of the sea surface from which the effects of tropical cyclones on sea surface emissivity can be measured. The emissivity at these frequencies is a function of sea surface salinity (SSS), sea surface temperature (SST), sea surface roughness, polarization, and angle of emission. If the latter four variables can be estimated, then models of the sea surface emissivity can be used to invert SSS from measured brightness temperature (TB). Actual measured TB from space also has affects due to the ionosphere and troposphere, which have to be compensated for, and components due to the galactic and cosmic background radiation those have to be removed. In this research, we study the relationships between retrieved SSS from MIRAS, and SST and precipitation collected by the NASA TMI sensor from the Tropical Rainfall Measuring Mission (TRMM) satellite during Hurricane Isaac, in August 2012. During the slower movement of the storm, just before landfall on the vicinity of the Louisiana Shelf, higher precipitation amounts were associated with lower SSS and slightly increased SST. This increased trend of SST and lower SSS under regions of high precipitation are indicative of inhibited vertical mixing. The SMOS Level 2 SSS were filtered by a stepwise process with removal of high uncertainty in TB under conditions of strong surface roughness which are known to create noise. The signature of increased SST associated with increasing precipitation was associated with decreased SSS during the storm. Although further research is required, this study

  3. Microwave Interferometric Radiometry in Remote Sensing: an Invited Historical Review

    NASA Technical Reports Server (NTRS)

    Martin-Neira, M.; LeVine, D. M.; Kerr, Y.; Skou, N.; Peichl, M.; Camps, A.; Corbella, I.; Hallikainen, M.; Font, J.; Wu, J.; Mecklenburg, S.; Drusch, M.

    2014-01-01

    The launch of the Soil Moisture and Ocean Salinity (SMOS) mission on 2 November 2009 marked a milestone in remote sensing for it was the first time a radiometer capable of acquiring wide field of view images at every single snapshot, a unique feature of the synthetic aperture technique, made it to space. The technology behind such an achievement was developed, thanks to the effort of a community of researchers and engineers in different groups around the world. It was only because of their joint work that SMOS finally became a reality. The fact that the European Space Agency, together with CNES (Centre National d'Etudes Spatiales) and CDTI (Centro para el Desarrollo Tecnológico e Industrial), managed to get the project through should be considered a merit and a reward for that entire community. This paper is an invited historical review that, within a very limited number of pages, tries to provide insight into some of the developments which, one way or another, are imprinted in the name of SMOS.

  4. Microwave interferometric radiometry in remote sensing: An invited historical review

    NASA Astrophysics Data System (ADS)

    Martín-Neira, M.; LeVine, D. M.; Kerr, Y.; Skou, N.; Peichl, M.; Camps, A.; Corbella, I.; Hallikainen, M.; Font, J.; Wu, J.; Mecklenburg, S.; Drusch, M.

    2014-06-01

    The launch of the Soil Moisture and Ocean Salinity (SMOS) mission on 2 November 2009 marked a milestone in remote sensing for it was the first time a radiometer capable of acquiring wide field of view images at every single snapshot, a unique feature of the synthetic aperture technique, made it to space. The technology behind such an achievement was developed, thanks to the effort of a community of researchers and engineers in different groups around the world. It was only because of their joint work that SMOS finally became a reality. The fact that the European Space Agency, together with CNES (Centre National d'Etudes Spatiales) and CDTI (Centro para el Desarrollo Tecnológico e Industrial), managed to get the project through should be considered a merit and a reward for that entire community. This paper is an invited historical review that, within a very limited number of pages, tries to provide insight into some of the developments which, one way or another, are imprinted in the name of SMOS.

  5. Microwave-induced thermogenetic activation of single cells

    SciTech Connect

    Safronov, N. A.; Fedotov, I. V.; Ermakova, Yu. G.; Matlashov, M. E.; Belousov, V. V.; Sidorov-Biryukov, D. A.; Fedotov, A. B.; Zheltikov, A. M.

    2015-04-20

    Exposure to a microwave field is shown to enable thermogenetic activation of individual cells in a culture of cell expressing thermosensitive ion channels. Integration of a microwave transmission line with an optical fiber and a diamond quantum thermometer has been shown to allow thermogenetic single-cell activation to be combined with accurate local online temperature measurements based on an optical detection of electron spin resonance in nitrogen–vacancy centers in diamond.

  6. Soil moisture sensing via swept frequency based microwave sensors.

    PubMed

    Pelletier, Mathew G; Karthikeyan, Sundar; Green, Timothy R; Schwartz, Robert C; Wanjura, John D; Holt, Greg A

    2012-01-01

    There is a need for low-cost, high-accuracy measurement of water content in various materials. This study assesses the performance of a new microwave swept frequency domain instrument (SFI) that has promise to provide a low-cost, high-accuracy alternative to the traditional and more expensive time domain reflectometry (TDR). The technique obtains permittivity measurements of soils in the frequency domain utilizing a through transmission configuration, transmissometry, which provides a frequency domain transmissometry measurement (FDT). The measurement is comparable to time domain transmissometry (TDT) with the added advantage of also being able to separately quantify the real and imaginary portions of the complex permittivity so that the measured bulk permittivity is more accurate that the measurement TDR provides where the apparent permittivity is impacted by the signal loss, which can be significant in heavier soils. The experimental SFI was compared with a high-end 12 GHz TDR/TDT system across a range of soils at varying soil water contents and densities. As propagation delay is the fundamental measurement of interest to the well-established TDR or TDT technique; the first set of tests utilized precision propagation delay lines to test the accuracy of the SFI instrument's ability to resolve propagation delays across the expected range of delays that a soil probe would present when subjected to the expected range of soil types and soil moisture typical to an agronomic cropping system. The results of the precision-delay line testing suggests the instrument is capable of predicting propagation delays with a RMSE of +/-105 ps across the range of delays ranging from 0 to 12,000 ps with a coefficient of determination of r(2) = 0.998. The second phase of tests noted the rich history of TDR for prediction of soil moisture and leveraged this history by utilizing TDT measured with a high-end Hewlett Packard TDR/TDT instrument to directly benchmark the SFI instrument over

  7. Estimation of Soil Moisture Profile using a Simple Hydrology Model and Passive Microwave Remote Sensing

    NASA Technical Reports Server (NTRS)

    Soman, Vishwas V.; Crosson, William L.; Laymon, Charles; Tsegaye, Teferi

    1998-01-01

    Soil moisture is an important component of analysis in many Earth science disciplines. Soil moisture information can be obtained either by using microwave remote sensing or by using a hydrologic model. In this study, we combined these two approaches to increase the accuracy of profile soil moisture estimation. A hydrologic model was used to analyze the errors in the estimation of soil moisture using the data collected during Huntsville '96 microwave remote sensing experiment in Huntsville, Alabama. Root mean square errors (RMSE) in soil moisture estimation increase by 22% with increase in the model input interval from 6 hr to 12 hr for the grass-covered plot. RMSEs were reduced for given model time step by 20-50% when model soil moisture estimates were updated using remotely-sensed data. This methodology has a potential to be employed in soil moisture estimation using rainfall data collected by a space-borne sensor, such as the Tropical Rainfall Measuring Mission (TRMM) satellite, if remotely-sensed data are available to update the model estimates.

  8. Dopant activation in ion implanted silicon by microwave annealing

    SciTech Connect

    Alford, T. L.; Thompson, D. C.; Mayer, J. W.; Theodore, N. David

    2009-12-01

    Microwaves are used as a processing alternative for the electrical activation of ion implanted dopants and the repair of ion implant damage within silicon. Rutherford backscattering spectra demonstrate that microwave heating reduces the damage resulting from ion implantation of boron or arsenic into silicon. Cross-section transmission electron microscopy and selective area electron diffraction patterns demonstrate that the silicon lattice regains nearly all of its crystallinity after microwave processing of arsenic implanted silicon. Sheet resistance readings indicate the time required for boron or arsenic electrical activation within implanted silicon. Hall measurements demonstrate the extent of dopant activation after microwave heating of implanted silicon. Physical and electrical characterization determined that the mechanism of recrystallization in arsenic implanted silicon is solid phase epitaxial regrowth. The boron implanted silicon samples did not result in enough lattice damage to amorphize the silicon lattice and resulted in low boron activation during microwave annealing even though recrystallization of the Si lattice damage did take place. Despite low boron activation levels, the level of boron activation in this work was higher than that expected from traditional annealing techniques. The kinetics of microwave heating and its effects on implanted Si are also discussed.

  9. Earth Science Microwave Remote Sensing at NASA's Goddard Space Flight Center

    NASA Technical Reports Server (NTRS)

    Kim, Edward; Busalacchi, Antonio J. (Technical Monitor)

    2000-01-01

    The Goddard Space Flight Center (GSFC) was established as NASA's first space flight center in 1959. Its 12,000 personnel are active in the Earth and space sciences, astronomy, space physics, tracking and communications. GSFC's mission is to expand our knowledge of the Earth and its environment, the solar system, and the universe through observations from space. The main Goddard campus is located in Greenbelt, Maryland, USA, just north of Washington, D.C. The Wallops Flight Facility (operational since 1945), located on the Atlantic coast of Virginia was consolidated with the Goddard Space Flight Center in 1982. Wallops is now NASA's principal facility for management and implementation of suborbital research programs, and supports a wide variety of airborne science missions as well. As the lead Center for NASA's Earth Science Enterprise (ESE)--a long-term, coordinated research effort to study the Earth as a global environmental system--GSFC scientists and engineers are involved in a wide range of Earth Science remote sensing activities. Their activities range from basic geoscience research to the development of instruments and technology for space missions, as well as the associated Calibration/Validation (Cal/Val) work. The shear breadth of work in these areas precludes an exhaustive description here. Rather, this article presents selected brief overviews of microwave-related Earth Science applications and the ground-based, airborne, and space instruments that are in service, under development, or otherwise significantly involving GSFC. Likewise, contributing authors are acknowledged for each section, but the results and projects they describe represent the cumulative efforts of many persons at GSFC as well as at collaborating institutions. For further information, readers are encouraged to consult the listed websites and references.

  10. Inversion algorithms for the microwave remote sensing of soil moisture. Experiments with swept frequency microwaves

    NASA Technical Reports Server (NTRS)

    Hancock, G. D.; Waite, W. P.

    1984-01-01

    Two experiments were performed employing swept frequency microwaves for the purpose of investigating the reflectivity from soil volumes containing both discontinuous and continuous changes in subsurface soil moisture content. Discontinuous moisture profiles were artificially created in the laboratory while continuous moisture profiles were induced into the soil of test plots by the environment of an agricultural field. The reflectivity for both the laboratory and field experiments was measured using bi-static reflectometers operated over the frequency ranges of 1.0 to 2.0 GHz and 4.0 to 8.0 GHz. Reflectivity models that considered the discontinuous and continuous moisture profiles within the soil volume were developed and compared with the results of the experiments. This comparison shows good agreement between the smooth surface models and the measurements. In particular the comparison of the smooth surface multi-layer model for continuous moisture profiles and the yield experiment measurements points out the sensitivity of the specular component of the scattered electromagnetic energy to the movement of moisture in the soil.

  11. Passive Microwave Remote Sensing of Falling Snow and Associated GPM Field Campaigns

    NASA Technical Reports Server (NTRS)

    Skofronick-Jackson, Gail

    2011-01-01

    Retrievals of falling snow from space represent one of the next important challenges for the atmospheric, hydrological, and energy budget scientific communities. Historically, retrievals of falling snow have been difficult due to the relative insensitivity of satellite rain-based channels as used in the past. We emphasize the use of high frequency passive microwave channels (85-200 GHz) since these are more sensitive to the ice in clouds and have been used to estimate falling snow from space. While satellite-based remote sensing provides global coverage of falling snow events and the science is relatively new, retrievals are still undergoing development with challenges remaining. There are several current satellite sensors, though not specifically designed for estimating falling snow, are capable of measuring snow from space. These include NOAA's AMSU-B, the MHS sensors, and CloudSat radar. They use high frequency (greater than 85 GHz) passive and active microwave and millimeter-wave channels that are sensitive to the scattering from ice and snow particles in the atmosphere. Sensors with water vapor channels near 183 GHz center line provide opaqueness to the Earth's surface features that can contaminate the falling snow signatures, especially over snow covered surface. In addition, the Global Precipitation Measurement (GPM) mission scheduled for launch in 2013 is specifically designed to measure both liquid rain and frozen snow precipitation. Since falling snow from space is the next precipitation measurement challenge from space, information must be determined in order to guide retrieval algorithm development for these current and future missions. This information includes thresholds of detection for various sensor channel configurations, snow event system characteristics, and surface types. For example, can a lake effect snow system with low cloud tops having an ice water content (IWC) at the surface of 1.0 gram per cubic meter be detected? If this information is

  12. Spatially continuous distributed fiber optic sensing using optical carrier based microwave interferometry.

    PubMed

    Huang, Jie; Lan, Xinwei; Luo, Ming; Xiao, Hai

    2014-07-28

    This paper reports a spatially continuous distributed fiber optic sensing technique using optical carrier based microwave interferometry (OCMI), in which many optical interferometers with the same or different optical path differences are interrogated in the microwave domain and their locations can be unambiguously determined. The concept is demonstrated using cascaded weak optical reflectors along a single optical fiber, where any two arbitrary reflectors are paired to define a low-finesse Fabry-Perot interferometer. While spatially continuous (i.e., no dark zone), fully distributed strain measurement was used as an example to demonstrate the capability, the proposed concept may also be implemented on other types of waveguide or free-space interferometers and used for distributed measurement of various physical, chemical and biological quantities. PMID:25089493

  13. Allometric Relationships in Soybean to Estimate the Effect of Vegetation on Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Spencer, A. J.; Hornbuckle, B. K.; Patton, J.

    2011-12-01

    Microwave remote sensing is capable of developing soil moisture maps through satellite data. The resulting maps are useful indicators of hydrologic conditions. Water concentrations are deterministic of flooding events and potential agricultural resources. The emitted microwave radiation of soil is influenced by its moisture content. Models have been developed to incorporate parameters besides soil moisture that affect the emitted microwave radiation. We are interested in one of these parameters known as the optical depth. Optical depth is the effect of the canopy on the observed emission of microwaves. The vegetation directly competes with soil moisture as a contributor to the emitted microwave radiation and the optical depth appears within every term in the present satellite retrieval algorithm. Optical depth has been shown to be directly proportional to the amount of water contained within vegetation tissue. Allometry is a way to effectively and efficiently measure vegetation water content through the way the parts of the organism change in proportion to each other in response to growth. Vegetation water content is difficult to measure without taking destructive measurements, in addition to involving too much time and manual labor. Therefore, another component of vegetation can be measured in relation to vegetation water content which can then be related to optical depth. In our study we worked in soybean, a major crop in many areas of the world. We compared soybean vegetation water content to an estimate of the volume of an individual plant expressed as the product of canopy height and stem diameter squared (Zc*Sd2), both of which can be measured easily and nondestructively. We also wished to determine whether vegetation water content remained constant as a percentage to total biomass over the length of the growing season. Agricultural yield is most likely a function of the total dry mass of vegetation. Establishing the relationship between vegetation water

  14. Correlating rainfall with remotely sensed microwave radiation using physically based models

    NASA Technical Reports Server (NTRS)

    Camillo, P. J.; Schmugge, T. J.

    1984-01-01

    This simulation study evaluates the response of a 21-cm radiometer, measuring the radiation emitted by a bare soil, to varying accumulations of rain. It is shown that correlations between the decrease in emissivity after a rain storm and the total accumulation depend strongly on the physical characteristics of the soil which affect its capacity to hold water. These are primarily soil texture and pre-rain soil moisture. A method is also discussed which would use the numerical models with remotely sensed microwave brightness and surface physical temperatures, along with conventional weather data, to estimate the total accumulation.

  15. Microwave assisted combustion synthesis of nanocrystalline CoFe2O4 for LPG sensing

    NASA Astrophysics Data System (ADS)

    Chaudhari, Prashant; Acharya, S. A.; Darunkar, S. S.; Gaikwad, V. M.

    2015-08-01

    A microwave-assisted citrate precursor method has been utilized for synthesis of nanocrystalline powders of CoFe2O4. The process takes only a few minutes to obtain as-synthesized CoFe2O4. Structural properties of the synthesized material were investigated by X-ray diffraction; scanning electron microscopy, Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy. The gas sensing properties of thick film of CoFe2O4 prepared by screen printing towards Liquid Petroleum Gas (LPG) revealed that CoFe2O4 thick films are sensitive and shows maximum sensitivity at 350°C for 2500 ppm of LPG.

  16. On direct passive microwave remote sensing of sea spray aerosol production

    NASA Astrophysics Data System (ADS)

    Savelyev, I. B.; Anguelova, M. D.; Frick, G. M.; Dowgiallo, D. J.; Hwang, P. A.; Caffrey, P. F.; Bobak, J. P.

    2014-11-01

    This study addresses and attempts to mitigate persistent uncertainty and scatter among existing approaches for determining the rate of sea spray aerosol production by breaking waves in the open ocean. The new approach proposed here utilizes passive microwave emissions from the ocean surface, which are known to be sensitive to surface roughness and foam. Direct, simultaneous, and collocated measurements of the aerosol production and microwave emissions were collected aboard the FLoating Instrument Platform (FLIP) in deep water ~ 150 km off the coast of California over a period of ~ 4 days. Vertical profiles of coarse-mode aerosol (0.25-23.5 μm) concentrations were measured with a forward-scattering spectrometer and converted to surface flux using dry deposition and vertical gradient methods. Back-trajectory analysis of eastern North Pacific meteorology verified the clean marine origin of the sampled air mass over at least 5 days prior to measurements. Vertical and horizontal polarization surface brightness temperature were measured with a microwave radiometer at 10.7 GHz frequency. Data analysis revealed a strong sensitivity of the brightness temperature polarization difference to the rate of aerosol production. An existing model of microwave emission from the ocean surface was used to determine the empirical relationship and to attribute its underlying physical basis to microwave emissions from surface roughness and foam within active and passive phases of breaking waves. A possibility of and initial steps towards satellite retrievals of the sea spray aerosol production are briefly discussed in concluding remarks.

  17. On direct passive microwave remote sensing of sea spray aerosol production

    NASA Astrophysics Data System (ADS)

    Savelyev, I. B.; Anguelova, M. D.; Frick, G. M.; Dowgiallo, D. J.; Hwang, P. A.; Caffrey, P. F.; Bobak, J. P.

    2014-06-01

    This study addresses and attempts to mitigate persistent uncertainty and scatter among existing approaches for determining the rate of sea spray aerosol production by breaking waves in the open ocean. The new approach proposed here utilizes passive microwave emissions from the ocean surface, which are known to be sensitive to surface roughness and foam. Direct, simultaneous, and collocated measurements of the aerosol production and microwave emissions were collected on-board FLoating Instrument Platform (FLIP) in deep water ∼150 km off the coast of California over a period of ∼4 days. Vertical profiles of coarse-mode aerosol (0.25-23.5 μm) concentrations were measured with a forward scattering spectrometer and converted to surface flux using dry deposition and vertical gradient methods. Back trajectory analysis of Northeast Pacific meteorology verified the clean marine origin of the sampled air mass over at least 5 days prior to measurements. Vertical and horizontal polarization surface brightness temperatures were measured with a microwave radiometer at 10.7 GHz frequency. Data analysis revealed a strong sensitivity of the brightness temperature polarization difference to the rate of aerosol production. An existing model of microwave emission from the ocean surface was used to determine the empirical relationship and to attribute its underlying physical basis to microwave emissions from surface roughness and foam within active and passive phases of breaking waves. A possibility of and initial steps towards satellite retrievals of the sea spray aerosol production are briefly discussed in concluding remarks.

  18. MICROWAVE REMOTE SENSING OF PLANETARY ATMOSPHERES: THE 50 YEARS FROM MARINER 2 TO NASA-JUNO

    NASA Astrophysics Data System (ADS)

    Steffes, Paul G.

    2013-10-01

    In November 2012, the world celebrated the 50th anniversary of spacecraft-based exploration of planets and satellites other our own. The first successful interplanetary mission (Mariner 2) included the first spaceborne microwave radiometer for studying planetary atmospheres which measured the 1.3 and 2.0 cm emission spectrum of Venus (also known as the Cytherean spectrum), These measurements, plus accompanying earth-based observations of the centimeter-wavelength spectrum were used to establish early models of the composition and structure of Venus. Shortly thereafter, measurements of the microwave emission spectrum of Jupiter (also known as the Jovian spectrum) from 1.18 to 1.58 cm were conducted. In both sets of observations, wavelengths near the 1.35 cm water-vapor resonance were selected in hope of detecting the spectral signature of water vapor, but none was found. Thus the question remained, “where’s the water?” The NASA-Juno mission is the first mission since Mariner 2 to carry a microwave radiometer instrument designed specifically for atmospheric sensing. It is expected to finally detect water in the Jovian atmosphere.

  19. Active and passive microwave measurements in Hurricane Allen

    NASA Technical Reports Server (NTRS)

    Delnore, V. E.; Bahn, G. S.; Grantham, W. L.; Harrington, R. F.; Jones, W. L.

    1985-01-01

    The NASA Langley Research Center analysis of the airborne microwave remote sensing measurements of Hurricane Allen obtained on August 5 and 8, 1980 is summarized. The instruments were the C-band stepped frequency microwave radiometer and the Ku-band airborne microwave scatterometer. They were carried aboard a NOAA aircraft making storm penetrations at an altitude of 3000 m and are sensitive to rain rate, surface wind speed, and surface wind vector. The wind speed is calculated from the increase in antenna brightness temperature above the estimated calm sea value. The rain rate is obtained from the difference between antenna temperature increases measured at two frequencies, and wind vector is determined from the sea surface normalized radar cross section measured at several azimuths. Comparison wind data were provided from the inertial navigation systems aboard both the C-130 aircraft at 3000 m and a second NOAA aircraft (a P-3) operating between 500 and 1500 m. Comparison rain rate data were obtained with a rain radar aboard the P-3. Evaluation of the surface winds obtained with the two microwave instruments was limited to comparisons with each other and with the flight level winds. Two important conclusions are drawn from these comparisons: (1) the radiometer is accurate when predicting flight level wind speeds and rain; and (2) the scatterometer produces well behaved and consistent wind vectors for the rain free periods.

  20. Low-cost microwave radiometry for remote sensing of soil moisture

    NASA Astrophysics Data System (ADS)

    Chikando, Eric Ndjoukwe

    2007-12-01

    Remote sensing is now widely regarded as a dominant means of studying the Earth and its surrounding atmosphere. This science is based on blackbody theory, which states that all objects emit broadband electromagnetic radiation proportional to their temperature. This thermal emission is detectable by radiometers---highly sensitive receivers capable of measuring extremely low power radiation across a continuum of frequencies. In the particular case of a soil surface, one important parameter affecting the emitted radiation is the amount of water content or, soil moisture. A high degree of precision is required when estimating soil moisture in order to yield accurate forecasting of precipitations and short-term climate variability such as storms and hurricanes. Rapid progress within the remote sensing community in tackling current limitations necessitates an awareness of the general public towards the benefits of the science. Information about remote sensing instrumentation and techniques remain inaccessible to many higher-education institutions due to the high cost of instrumentation and the current general inaccessibility of the science. In an effort to draw more talent within the field, more affordable and reliable scientific instrumentation are needed. This dissertation introduces the first low-cost handheld microwave instrumentation fully capable of surface soil moisture studies. The framework of this research is two-fold. First, the development of a low-cost handheld microwave radiometer using the well-known Dicke configuration is examined. The instrument features a super-heterodyne architecture and is designed following a microwave integrated circuit (MIC) system approach. Validation of the instrument is performed by applying it to various soil targets and comparing measurement results to gravimetric technique measured data; a proven scientific method for determining volumetric soil moisture content. Second, the development of a fully functional receiver RF front

  1. Microwave-heating synthesis and sensing applications of bright gold nanoclusters

    SciTech Connect

    He, Ding-Fei; Xiang, Yang; Wang, Xu; Yu, Xue-Feng

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We establish a microwave-heating method to synthesize protein-stabilized Au nanoclusters. Black-Right-Pointing-Pointer The obtained Au nanoclusters show bright red fluorescence. Black-Right-Pointing-Pointer The Au nanoclusters can be used as efficient fluorescence probe for Cu{sup 2+} ion sensing. -- Abstract: A rapid microwave-heating method has been developed for the synthesis of bright Au nanoclusters by using bull serum albumin as the template in an aqueous environment. The reaction time needed is only 7.0 min, and the weight of the products at one batch can reach 15 g. The Au nanoclusters exhibit bright fluorescence at {approx}613 nm with quantum yield of {approx}6.0%. By adjusting the pH value, the products can be controlled to precipitate or re-disperse in aqueous solution. Furthermore, the Au nanoclusters have exhibited high sensitivity and selectivity in the determination of Cu{sup 2+} ions in water. These results suggest an efficient method for obtaining metal nanoclusters for the detection and sensing applications.

  2. Microwave Intercalation Synthesis of WO3 Nanoplates and Their NO-Sensing Properties

    NASA Astrophysics Data System (ADS)

    Tu, Yue; Li, Qiang; Jiang, Danyu; Wang, Qi; Feng, Tao

    2015-01-01

    Tungsten(VI) oxide (WO3) nanoplates were successfully synthesized by microwave intercalation. Through microwave processing, an intermediate product H2W2O7· xH2O was prepared quickly to greatly decrease the time used to prepare WO3 nanoplates. The crystal structure and morphology of WO3 were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and selected-area electron diffraction. The morphology of WO3 changed with an increase in calcining temperature. A mixed-potential NO x sensor using planar yttria-stabilized zirconia and WO3 as the sensing electrode (SE) was fabricated, and its performance in NO x detection at high temperature was examined. It was determined that at 500 °C, the sensor with the WO3-nanoplate SE had higher sensitivity to NO than the sensor with a SE consisting of WO3 microparticles. The response of the NO sensor with a WO3-nanoplate SE was linear with the logarithm of NO concentration in the range of 100-1000 ppm. The electrochemical impedance measurements indicate that the electrode reaction that occurred at the triple-phase boundary (TPB) of the sensor with WO3-nanoplate SE was stronger than the reaction that occurred at the TPB of the sensor with WO3-microparticle sensing electrode.

  3. Research on estimation crop planting area by integrating the optical and microwave remote sensing data

    NASA Astrophysics Data System (ADS)

    Liu, Jiang; Yu, Fan; Liu, Dandan; Tian, Jing; Zhang, Weicheng; Wang, Qiang; Yang, Jinling; Zhang, Lei

    2015-12-01

    Considering the problem in monitoring agricultural condition in the semi-arid areas of Northwest of China, we propose a new method for estimation of crop planting area, using the single phase optical and microwave remote sensing data collaboratively, which have demonstrated their respective advantages in the extraction of surface features. In the model, the ASAR backscatter coefficient is normalized by the incident angle at first, then the classifier based on Bayesian network is developed, and the VV, VH polarization of ASAR and all the 7 TM bands are taken as the input of the classifier to get the class labels of each pixel of the images. Moreover the crop planting areas can be extracted by the classification results. At last, the model is validated for the necessities of normalization by the incident angle and integration of TM and ASAR respectively. It results that the estimation accuracy of crop planting area of corn and other crops garden are 98.47% and 78.25% respectively using the proposed method, with an improvement of estimation accuracy of about 3.28% and 4.18% relative to single TM classification. These illustrate that synthesis of optical and microwave remote sensing data is efficient and potential in estimation crop planting area.

  4. Annual South American Forest Loss Estimates (1989-2011) Based on Passive Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    van Marle, M.; van der Werf, G.; de Jeu, R.; Liu, Y.

    2014-12-01

    Vegetation dynamics, such as forest loss, are an important factor in global climate, but long-term and consistent information on these dynamics on continental scales is lacking. We have quantified large-scale forest loss over the 90s and 00s in the tropical biomes of South America using a passive-microwave satellite-based vegetation product. Our forest loss estimates are based on remotely sensed vegetation optical depth (VOD), which is an indicator of vegetation water content simultaneously retrieved with soil moisture. The advantage of low-frequency microwave remote sensing is that aerosols and clouds do not affect the observations. Furthermore, the longer wavelengths of passive microwaves penetrate deeper into vegetation than other products derived from optical and thermal sensors. This has the consequence that both woody parts of vegetation and leaves can be observed. The merged VOD product of AMSR-E and SSM/I observations, which covers over 23 years of daily observations, is used. We used this data stream and an outlier detection algorithm to quantify spatial and temporal variations in forest loss dynamics. Qualitatively, our results compared favorably to the newly developed Global Forest Change (GFC) maps based on Landsat data (r2=0.96), and this allowed us to convert the VOD outlier count to forest loss. Our results are spatially explicit with a 0.25-degree resolution and annual time step and we will present our estimates on country level. The added benefit of our results compared to GFC is the longer time period. The results indicate a relatively steady increase in forest loss in Brazil from 1989 until 2003, followed by two high forest loss years and a declining trend afterwards. This contrasts with other South American countries such as Bolivia and Peru, where forest losses increased in almost the whole 00s in comparison with the 90s.

  5. Indicators of international remote sensing activities

    NASA Technical Reports Server (NTRS)

    Spann, G. W.

    1977-01-01

    The extent of worldwide remote sensing activities, including the use of satellite and high/medium altitude aircraft data was studied. Data were obtained from numerous individuals and organizations with international remote sensing responsibilities. Indicators were selected to evaluate the nature and scope of remote sensing activities in each country. These indicators ranged from attendance at remote sensing workshops and training courses to the establishment of earth resources satellite ground stations and plans for the launch of earth resources satellites. Results indicate that this technology constitutes a rapidly increasing component of environmental, land use, and natural resources investigations in many countries, and most of these countries rely on the LANDSAT satellites for a major portion of their data.

  6. High-Resolution Daily Flood Extent Depiction from Microwave Remote Sensing: Global Results

    NASA Astrophysics Data System (ADS)

    Galantowicz, J. F.

    2015-12-01

    The need for frequent, accurate, high-resolution characterization of the temporal and spatial progression of flood hazards is evident, but has been beyond the capabilities of remote sensing methods. The surface is too often obscured by cloud cover for visual and infrared sensors and observations from radar sensors are too infrequent to create consistent historical databases or for monitoring current conditions. Passive microwave sensors, such as SSM/I, AMSR-E, and AMSR-2, acquire useful data during clear and cloudy conditions, have revisit periods of up to twice daily, and provide a continuous record of data from 1987 to the present. In this presentation, we will describe results from a flood mapping system capable of producing high-resolution (100-m) flood extent depictions from lower resolution (10-40-km) microwave data. The system uses the strong sensitivity of microwave data to surface water extent combined with land surface and atmospheric data to derive daily flooded fraction estimates globally on a sensor footprint basis. The system downscales flooded fraction to make a high-resolution Boolean flood extent depiction that is both spatially continuous and consistent with the lower resolution data (see Figure). The downscaling step is based on a relative floodability index derived from higher resolution topographic and hydrological data and processed to represent the minimum total water fraction threshold above which each grid point is expected to be flooded given microwave-derived water fraction inputs. We have completed daily, 100-m resolution flood maps for Africa for the 9.3-year AMSR-E period and will soon complete global flood maps fo the same period. We will present animations of daily flood extents during major events and discuss: validation of the flood maps against imagery derived from MODIS and Landsat data; analyses of minimum detectable flood size; statistical analyses of flooding over time; applications for this novel historical dataset; and

  7. Active microwave classification of sea ice

    NASA Technical Reports Server (NTRS)

    Onstott, Robert G.

    1989-01-01

    Radar backscatter studies of Arctic sea ice have been carried out over a number of years with the intent to acquire physical property information through the examination of microwave signatures. The breadth of these studies continues to expand; as an example, measurements are now conducted at frequencies from 500 MHz to about 100 GHz. One of the scientific goals of this work has been to develop an improved outstanding of the scattering processes at play. A second, equally important goal has been to apply the knowledge gained in examining the backscatter response of ice and snow made in conjunction with the detailed scene characterizations, the insight gained through theoretical modeling and parametric study, and the data entered into the radar signature library to develop procedures to convert microwave signal information (available in the very near future) into valuable data products. This should ultimately provide a better understanding of the environment. The author discusses what has been learned through the many efforts associated with the near-surface scatterometer measurement programs and how the knowledge gained is assisting in the development of future sea ice type satellite algorithms. The logic and mechanisms used in discriminating sea ice types are presented.

  8. Remote Sensing of the Arctic Seas.

    ERIC Educational Resources Information Center

    Weeks, W. F.; And Others

    1986-01-01

    Examines remote sensing of the arctic seas by discussing: (1) passive microwave sensors; (2) active microwave sensors; (3) other types of sensors; (4) the future deployment of sensors; (5) data buoys; and (6) future endeavors. (JN)

  9. Synergy between optical and microwave remote sensing to derive soil and vegetation parameters from MAC Europe 1991 Experiment

    NASA Technical Reports Server (NTRS)

    Taconet, O.; Benallegue, M.; Vidal, A.; Vidal-Madjar, D.; Prevot, L.; Normand, M.

    1993-01-01

    The ability of remote sensing for monitoring vegetation density and soil moisture for agricultural applications is extensively studied. In optical bands, vegetation indices (NDVI, WDVI) in visible and near infrared reflectances are related to biophysical quantities as the leaf area index, the biomass. In active microwave bands, the quantitative assessment of crop parameters and soil moisture over agricultural areas by radar multiconfiguration algorithms remains prospective. Furthermore the main results are mostly validated on small test sites, but have still to be demonstrated in an operational way at a regional scale. In this study, a large data set of radar backscattering has been achieved at a regional scale on a French pilot watershed, the Orgeval, along two growing seasons in 1988 and 1989 (mainly wheat and corn). The radar backscattering was provided by the airborne scatterometer ERASME, designed at CRPE, (C and X bands and HH and VV polarizations). Empirical relationships to estimate water crop and soil moisture over wheat in CHH band under actual field conditions and at a watershed scale are investigated. Therefore, the algorithms developed in CHH band are applied for mapping the surface conditions over wheat fields using the AIRSAR and TMS images collected during the MAC EUROPE 1991 experiment. The synergy between optical and microwave bands is analyzed.

  10. Early Childhood: Developing Sense-activities.

    ERIC Educational Resources Information Center

    Shirah, Sue; Dorman, Mildred M.

    1989-01-01

    Described are science activities in which students concentrate on their senses and make discoveries with their eyes, ears, noses, mouths, and hands. Suggested experiments include activities involving cooking, tasting, observing, floating and sinking objects, making rain, and stringed musical instruments. (RT)

  11. Snowpack Microstructure Characterization and Partial Coherent and Fully Coherent Forward Scattering Models in Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Tan, S.; Tsang, L.; Xu, X.; Ding, K. H.

    2015-12-01

    In this paper we describe partial coherent model and fully coherent snowpack scattering model based on numerical simulation of Maxwell's equation. In medium characterization, we derive the correlation functions from the pair distribution functions of sticky spheres and multiple-size spheres used in QCA. We show that both the Percus-Yevick pair functions and the bicontinuous model have tails in the correlation functions that are distinctly different from the traditional exponential correlation functions. The methodologies of using ground measurements of grain size distributions and correlation functions to obtain model parameters are addressed. The DMRT theory has been extended to model the backscattering enhancement. We developed the methodology of cyclical corrections beyond first order to all orders of multiple scattering. This enables the physical modeling of combined active and passive microwave remote sensing of snow over the same scene. The bicontinuous /DMRT is applied to compare with data acquired in the NoSREx campaign, and the model results are validated against coincidental active and passive measurements using the same set of physical parameters of snow in all frequency and polarization channels. The DMRT is a partially coherent approach that one accounts for the coherent wave interaction only within few wavelengths as represented by phase matrix. However, the phase information of field is lost in propagating the specific intensity via RT and this hinders the use of DMRT in coherent synthetic aperture radar (SAR) analysis, including InSAR, PolInSAR and Tomo-SAR. One can alternatively calculate the scattering matrix of the terrestrial snowpack above ground by solving the volume integral equations directly with half space Green's function. The scattering matrix of the snowpack is computed for each realization giving rise to the speckle statistics. The resulting bistatic scattering automatically includes the backscattering enhancement effects. Tomograms of

  12. Monitoring Freeze-Thaw States in the Pan-Arctic: Application of Microwave Remote Sensing to Monitoring Hydrologic and Ecological Processes

    NASA Astrophysics Data System (ADS)

    McDonald, K. C.; Kimball, J. S.

    2004-12-01

    The transition of the landscape between predominantly frozen and non-frozen conditions in seasonally frozen environments impacts climate, hydrological, ecological and biogeochemical processes profoundly. Satellite microwave remote sensing is uniquely capable of detecting and monitoring a range of related biophysical processes associated with the measurement of landscape freeze/thaw status. We present the development, physical basis, current techniques and selected hydrological applications of satellite-borne microwave remote sensing of landscape freeze/thaw states for the terrestrial cryosphere. Major landscape hydrological processes embracing the remotely-sensed freeze/thaw signal include timing and spatial dynamics of seasonal snowmelt and associated soil thaw, runoff generation and flooding, ice breakup in large rivers and lakes, and timing and length of vegetation growing seasons and associated productivity and trace gas exchange. Employing both active and passive microwave sensors, we apply a selection of temporal change classification algorithms to examine a variety of hydrologic processes. We investigate contemporaneous and retrospective applications of the QuikSCAT scatterometer, and the SSM/I and SMMR radiometers to this end. Results illustrate the strong correspondence between regional thawing, seasonal ice break up for rivers, and the springtime pulse in river flow. We present the physical principles of microwave sensitivity to landscape freeze/thaw state, recent progress in applying these principles toward satellite remote sensing of freeze/thaw processes over broad regions, and potential for future global monitoring of this significant phenomenon of the global cryosphere. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, and at the University of Montana, Missoula, under contract to the National Aeronautics and Space Administration.

  13. Detection of Severe Rain on Snow events using passive microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Grenfell, T. C.; Putkonen, J.

    2007-12-01

    Severe wintertime rain-on-snow (ROS) events create a strong ice layer or layers in the snow on arctic tundra that act as a barrier to ungulate grazing. These events are linked with large-scale ungulate herd declines via starvation and reduced calf production rate when the animals are unable to penetrate through the resulting ice layer. ROS events also produce considerable perturbation in the mean wintertime soil temperature beneath the snow pack. ROS is a sporadic but well-known and significant phenomenon that is currently very poorly documented. Characterization of the distribution and occurrence of severe rain-on-snow events is based only on anecdotal evidence, indirect observations of carcasses found adjacent to iced snow packs, and irregular detection by a sparse observational weather network. We have analyzed in detail a particular well-identified ROS event that took place on Banks Island in early October 2003 that resulted in the death of 20,000 musk oxen. We make use of multifrequency passive microwave imagery from the special sensing microwave imager satellite sensor suite (SSM/I) in conjunction with a strong-fluctuation-theory (SFT) emissivity model. We show that a combination of time series analysis and cluster analysis based on microwave spectral gradients and polarization ratios provides a means to detect the stages of the ROS event resulting from the modification of the vertical structure of the snow pack, specifically wetting the snow, the accumulation of liquid water at the base of the snow during the rain event, and the subsequent modification of the snowpack after refreezing. SFT model analysis provides quantitative confirmation of our interpretation of the evolution of the microwave properties of the snowpack as a result of the ROS event. In particular, in addition to the grain coarsening due to destructive metamorphism, we detect the presence of the internal water and ice layers, directly identifying the physical properties producing the

  14. Remote-Sensing of Precipitation Characteristics Using Multi-frequency Microwave Links and Polarimetric Radar Techniques

    NASA Astrophysics Data System (ADS)

    Eastment, J. D.; Bradford, W. J.; Goddard, J. W.; Willis, M. J.

    2002-05-01

    The Radio Communications Research Unit at Rutherford Appleton Laboratory (RAL) currently operates two separate experimental studies aimed at characterising the properties of rainfall using microwave remote-sensing. The first study involves the use of dual-frequency microwave measurements of precipitation-induced attenuation on a number of radio paths spanning a river catchment area to estimate path-integrated rainfall rate. This data is of interest for hydrological research connected with urban drainage, river level management and flood forecasting. Dual-frequency attenuation measurements have been employed because theoretical modelling showed them to be far less sensitive to rainfall drop-size distribution effects than single-frequency data. The experimental network comprises 9 microwave links spanning the frequency range 13 to 38 GHz installed on 5 different paths covering the catchment area of the rivers Croal and Irwell near Bolton in North-West England. For each transmitter-receiver link, excess path attenuation relative to the clear-air value is determined from measurements of received signal power level at a rate of 1 Hz. These data are logged by local computers at each receiver site, and periodically downloaded by modem to RAL for archiving and quality control. Analysis by colleagues at the Universities of Essex and Salford has shown that, due to the path-integrated nature of the attenuation measurements and the wide area-coverage obtained by a suitable choice of the multiple-path geometry, a small number of dual-frequency links can provide comparable hydrological data to that obtained from the more conventional dense network of rain-gauges. The second study employs a scanning polarimetric Doppler radar developed by RAL to measure the spatial distribution of hydrometeors along various operational microwave and mm-wave communication links within a 50 km radius of the University of St. Andrews in South-East Scotland. The UK Radiocommunications Agency and

  15. Sensing Human Activity: GPS Tracking

    PubMed Central

    van der Spek, Stefan; van Schaick, Jeroen; de Bois, Peter; de Haan, Remco

    2009-01-01

    The enhancement of GPS technology enables the use of GPS devices not only as navigation and orientation tools, but also as instruments used to capture travelled routes: as sensors that measure activity on a city scale or the regional scale. TU Delft developed a process and database architecture for collecting data on pedestrian movement in three European city centres, Norwich, Rouen and Koblenz, and in another experiment for collecting activity data of 13 families in Almere (The Netherlands) for one week. The question posed in this paper is: what is the value of GPS as ‘sensor technology’ measuring activities of people? The conclusion is that GPS offers a widely useable instrument to collect invaluable spatial-temporal data on different scales and in different settings adding new layers of knowledge to urban studies, but the use of GPS-technology and deployment of GPS-devices still offers significant challenges for future research. PMID:22574061

  16. Low-cost electronic microwave calibration for rapid on-line moisture sensing of seedcotton.

    PubMed

    Pelletier, Mathew G; Viera, Joseph A

    2010-01-01

    In order to improve rapid on-line moisture sensing of seedcotton in cotton gins, a means by which to establish a reliable low-cost wide-band electronic calibration is critically needed. This calibration is needed to center the circuit due to changes in the internal signal delays and attenuation drift caused by temperature changes in the various system components and circuit elements. This research examines a hardware technique for use in conjunction with microwave reflective sensing probes having an extended bandwidth from 500 MHz through 2.5 GHz. This new technique was validated experimentally against known electrical propagation delay standards. Results of the measured propagation delay with this type of automatic electronic calibration method was found to agree with results using a vector network analyzer with a traditional S11 single port error correction calibration methodology to within 4% of the measurement, 95% confidence, with a standard error of +/-18.6 ps for the delay measurements. At this level of performance, the proposed low-cost technique exhibits superior performance, over the typical geosciences time-domain reflectometer "TDR", instruments in common use in soil moisture testing and is suitable for use in cotton gin moisture sensing. PMID:22163514

  17. Microwave Dielectric Sensing of Moisture Content in Shelled Peanuts Independent of Bulk Density and with Temperature Compensation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A dielectric method for rapid and nondestructive sensing of moisture content in shelled peanuts from free space measurement of attenuation, phase shift, and their corresponding dielectric properties at microwave frequencies is presented. Results of moisture prediction with three density-independent...

  18. Spatiotemporal analysis of soil moisture in using active and passive remotely sensed data and ground observations

    NASA Astrophysics Data System (ADS)

    Li, H.; Fang, B.; Lakshmi, V.

    2015-12-01

    Abstract: Soil moisture plays a vital role in ecosystem, biological processes, climate, weather and agriculture. The Soil Moisture Active Passive (SMAP) improves data by combining the advantages and avoiding the limitation of passive microwave remote sensing (low resolution), and active microwave (challenge of soil moisture retrieval). This study will advance the knowledge of the application of soil moisture by using the Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12) data as well as data collected at Walnut Gulch Arizona in August 2015 during SMAPVEX15. Specifically, we will analyze the 5m radar data from Unmanned Airborne Vehicle Synthetic Aperture Radar (UAVSAR) to study spatial variability within the PALS radiometer pixel. SMAPVEX12/15 and SMAP data will also be analyzed to evaluate disaggregation algorithms. The analytical findings will provide valuable information for policy-makers to initiate and adjust protocols and regulations for protecting land resources and improving environmental conditions. Keywords: soil moisture, Remote Sensing (RS), spatial statistic

  19. Satellite Microwave Remote Sensing for Environmental Modeling of Mosquito Population Dynamics.

    PubMed

    Chuang, Ting-Wu; Henebry, Geoffrey M; Kimball, John S; Vanroekel-Patton, Denise L; Hildreth, Michael B; Wimberly, Michael C

    2012-10-01

    Environmental variability has important influences on mosquito life cycles and understanding the spatial and temporal patterns of mosquito populations is critical for mosquito control and vector-borne disease prevention. Meteorological data used for model-based predictions of mosquito abundance and life cycle dynamics are typically acquired from ground-based weather stations; however, data availability and completeness are often limited by sparse networks and resource availability. In contrast, environmental measurements from satellite remote sensing are more spatially continuous and can be retrieved automatically. This study compared environmental measurements from the NASA Advanced Microwave Scanning Radiometer on EOS (AMSR-E) and in situ weather station data to examine their ability to predict the abundance of two important mosquito species (Aedes vexans and Culex tarsalis) in Sioux Falls, South Dakota, USA from 2005 to 2010. The AMSR-E land parameters included daily surface water inundation fraction, surface air temperature, soil moisture, and microwave vegetation opacity. The AMSR-E derived models had better fits and higher forecasting accuracy than models based on weather station data despite the relatively coarse (25-km) spatial resolution of the satellite data. In the AMSR-E models, air temperature and surface water fraction were the best predictors of Aedes vexans, whereas air temperature and vegetation opacity were the best predictors of Cx. tarsalis abundance. The models were used to extrapolate spatial, seasonal, and interannual patterns of climatic suitability for mosquitoes across eastern South Dakota. Our findings demonstrate that environmental metrics derived from satellite passive microwave radiometry are suitable for predicting mosquito population dynamics and can potentially improve the effectiveness of mosquito-borne disease early warning systems. PMID:23049143

  20. Satellite Microwave Remote Sensing for Environmental Modeling of Mosquito Population Dynamics

    PubMed Central

    Chuang, Ting-Wu; Henebry, Geoffrey M.; Kimball, John S.; VanRoekel-Patton, Denise L.; Hildreth, Michael B.; Wimberly, Michael C.

    2012-01-01

    Environmental variability has important influences on mosquito life cycles and understanding the spatial and temporal patterns of mosquito populations is critical for mosquito control and vector-borne disease prevention. Meteorological data used for model-based predictions of mosquito abundance and life cycle dynamics are typically acquired from ground-based weather stations; however, data availability and completeness are often limited by sparse networks and resource availability. In contrast, environmental measurements from satellite remote sensing are more spatially continuous and can be retrieved automatically. This study compared environmental measurements from the NASA Advanced Microwave Scanning Radiometer on EOS (AMSR-E) and in situ weather station data to examine their ability to predict the abundance of two important mosquito species (Aedes vexans and Culex tarsalis) in Sioux Falls, South Dakota, USA from 2005 to 2010. The AMSR-E land parameters included daily surface water inundation fraction, surface air temperature, soil moisture, and microwave vegetation opacity. The AMSR-E derived models had better fits and higher forecasting accuracy than models based on weather station data despite the relatively coarse (25-km) spatial resolution of the satellite data. In the AMSR-E models, air temperature and surface water fraction were the best predictors of Aedes vexans, whereas air temperature and vegetation opacity were the best predictors of Cx. tarsalis abundance. The models were used to extrapolate spatial, seasonal, and interannual patterns of climatic suitability for mosquitoes across eastern South Dakota. Our findings demonstrate that environmental metrics derived from satellite passive microwave radiometry are suitable for predicting mosquito population dynamics and can potentially improve the effectiveness of mosquito-borne disease early warning systems. PMID:23049143

  1. Photonic compressive sensing with a micro-ring-resonator-based microwave photonic filter

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Ding, Yunhong; Zhu, Zhijing; Chi, Hao; Zheng, Shilie; Zhang, Xianmin; Jin, Xiaofeng; Galili, Michael; Yu, Xianbin

    2016-08-01

    A novel approach to realize photonic compressive sensing (CS) with a multi-tap microwave photonic filter is proposed and demonstrated. The system takes both advantages of CS and photonics to capture wideband sparse signals with sub-Nyquist sampling rate. The low-pass filtering function required in the CS is realized in a photonic way by using a frequency comb and a dispersive element. The frequency comb is realized by shaping an amplified spontaneous emission (ASE) source with an on-chip micro-ring resonator, which is beneficial to the integration of photonic CS. A proof-of-concept experiment for a two-tone signal acquisition with frequencies of 350 MHz and 1.25 GHz is experimentally demonstrated with a compression factor up to 16.

  2. Microwave assisted synthesis of copper oxide and its application in electrochemical sensing

    NASA Astrophysics Data System (ADS)

    Felix, S.; Bala Praveen Chakkravarthy, R.; Nirmala Grace, A.

    2015-02-01

    Copper oxide nanopowders were prepared using copper acetate as the precursor and polyethylene glycol (PEG) as stabilizer in ethanol medium. The mixture containing copper acetate, sodium hydroxide and PEG was irradiated with microwave and nanometric copper oxide particles were formed within 8 min. The prepared nanoparticles were characterized using x-ray diffraction, UV-vis spectroscopy and scanning electron microscopy. The average particle size was found to be ~ 4 nm. This was used to modify glassy carbon electrode with PVDF & DMF as binder and used for sensing of carbohydrates (glucose and sucrose) and H2O2. The copper oxide nanoparticles showed excellent sensitivity in the range of 0.1 mM to 1 mM when choronoamperometry was carried out at 0.6 V Vs. Ag/AgCl. The observed sensitivity is much higher when compared with conventional micron sized copper oxide particles.

  3. Scattering in remote sensing in the visible and microwave spectral range and in traffic control

    NASA Astrophysics Data System (ADS)

    Böttger, U.; Kühne, R.; Thiessenhusene, K.-U.

    2003-05-01

    The treatment of scattering processes in remote sensing for interpretation of satellite data is demonstrated in the visible and microwave spectral range comparing the two spectral ranges. Analogies and distinctions in the treatment of the scattering processes are shown. Based on this cognition an approach for traffic simulation is outlined. Simulating the traffic of a part of a city, a whole city or a larger area in an acceptable time is one of the tasks in recent traffic research. One possible approach is the areal treatment of the road network. That means that single streets are not resolved but are introduced into simulations only by parameters that correspond to a specific traffic area resistance. The aim of this work is to outline such a possibility using experiences obtained from the theory of radiative transport to simulate scattering processes and applying them to the very complex system of traffic simulation.

  4. A new algorithm to measure sea ice concentration from passive microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Repina, Irina; Sharkov, Evgeniy; Komarova, Nataliya; Raev, Mikhail; Tikhonov, Vasilii; Boyarskiy, Dmitriy

    Studies of spatial and temporal properties of sea ice distribution in polar regions help to monitor global environmental changes and reveal their natural and anthropogenic factors, as well as make forecasts of weather, marine transportation and fishing conditions, assess perspectives of mineral mining on the continental shelf, etc. Contact methods of observation are often insufficient to meet the goals, very complicated technically and organizationally and not always safe for people involved. Remote sensing techniques are believed to be the best alternative. Its include monitoring of polar regions by means of passive microwave sensing with the aim to determine spatial distribution, types, thickness and snow cover of ice. However, the algorithms employed today to retrieve sea ice characteristics from passive microwave sensing data for different reasons give significant errors, especially in summer period and also near ice edges and in cases of open ice. One of the error sources is the current practice of using empirical dependencies and adjustment coefficients for the retrieval of ice characteristics and neglecting the physics of the process. We discuss an electrodynamic model of the sea surface - sea ice - snow cover - atmosphere system developed with account taken of physical and structural properties of the ambient. Model calculations of ice brightness temperature in different concentrations and snow covers are in good agreement with SSM/I measurement data. On the base of this model we develop a new algorithm for the retrieval of sea ice concentration from passive microwave sensing data - Variation Arctic Sea Ice Algorithm (VASIA). In contrast to the well-known techniques (NASA TEAM, Bootstrap, ASI, NORSEX et al), it takes into account the real physical parameters of ice, snow and open water rather than empirical and adjustment coefficients. Satellite data were provided by the POLE-RT-Fields SSM/I and SSMIS data collection for polar regions retrieved from the

  5. Remote sensing of precipitable water over the oceans from Nimbus-7 microwave measurements

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Change, H. D.; Chang, A. T. C.

    1981-01-01

    Global maps of precipitable water over derived from scanning multichannel microwave radiometer (SMMR) data reveal salient features associated with ocean currents and the large scale general circulation in the atmosphere. Nimbus-7 SMMR brightness temperature measurements in the 21 and 18 GHz channels are used to sense the precipitable water in the atmospheric over oceans. The difference in the brightness temperature (T sub 21 -T sub 18), both in the horizontal and vertical polarization, is found to be essentially a function of the precipitable water in the atmosphere. An equation, based on the physical consideration of the radiative transfer in the microwave region, is developed to relate the precipitable water to (T sub 21 - T sub 18). It shows that the signal (T sub 21- T sub 18) does not suffer severely from the noise introduced by variations in the sea surface temperature, surface winds, and liquid water content in non rain clouds. The rms deviation between the estimated precipitable water from SMMR data and that given by the closely coincident ship radiosondes is about 0.25 g/ sq cm

  6. Microwave remote sensing of physically buried objects in the Negev desert: Implications for subsurface Martian exploration

    NASA Astrophysics Data System (ADS)

    Daniels, Julian; Blumberg, Dan G.; Vulfson, Leonid D.; Kotlyar, Alex L.; Freiliker, Valentin; Ronen, Gefen; Ben-Asher, Jiftach

    2003-03-01

    We report the remote detection of a physically buried specular reflecting object using microwave radar at Ashalim in the northern region of the Negev desert, Israel. Such detection provides an important terrestrial analogy for the potential detection of specularly reflecting subsurfaces under the desiccated regolith on Mars, such as ground-ice and liquid water. At Ashalim, a scatterometer operating in the P-band (441 MHz, 68 cm) was mounted on a cherry picker truck at a height of 8 m and used to detect two triangular aluminum mesh reflectors (forming a one meter square area reflector) buried down to a depth of 8 cm in dry sand. The decrease in measured backscattered power with increasing burial depth of the reflector is clearly evident. The experimental results compare well with a theoretical model that incorporates radar absorption effects arising in the sandy subsurface layer and radar interference effects arising from phase differences between reflections from the surface and buried reflector. This experiment and the associated modeling approach is the first of a series of planned experiments, which we outline for the detection and the theoretical evaluation of buried reflectors using remote microwave and VHF radar. We identify many potential subject areas for subsurface remote sensing in the Martian domain, particularly groundwater/ground-ice.

  7. Remote Sensing Simulation Activities for Earthlings

    ERIC Educational Resources Information Center

    Krockover, Gerald H.; Odden, Thomas D.

    1977-01-01

    Suggested are activities using a Polaroid camera to illustrate the capabilities of remote sensing. Reading materials from the National Aeronautics and Space Administration (NASA) are suggested. Methods for (1) finding a camera's focal length, (2) calculating ground dimension photograph simulation, and (3) limiting size using film resolution are…

  8. Symbol Sense Behavior in Digital Activities

    ERIC Educational Resources Information Center

    Bokhove, Christian; Drijvers, Paul

    2010-01-01

    The algebraic expertise that mathematics education is aiming for includes both procedural skills and conceptual understanding. To capture the latter, notions such as symbol sense, gestalt view and visual salience have been developed. We wonder if digital activities can be designed that not only require procedural algebraic skills, but also invite…

  9. The NASA Airborne Earth Science Microwave Imaging Radiometer (AESMIR): A New Sensor for Earth Remote Sensing

    NASA Technical Reports Server (NTRS)

    Kim, Edward

    2003-01-01

    The Airborne Earth Science Microwave Imaging Radiometer (AESMIR) is a versatile new airborne imaging radiometer recently developed by NASA. The AESMIR design is unique in that it performs dual-polarized imaging at all standard passive microwave frequency bands (6-89 GHz) using only one sensor headscanner package, providing an efficient solution for Earth remote sensing applications (snow, soil moisture/land parameters, precipitation, ocean winds, sea surface temperature, water vapor, sea ice, etc.). The microwave radiometers themselves will incorporate state-of-the-art receivers, with particular attention given to instrument calibration for the best possible accuracy and sensitivity. The single-package design of AESMIR makes it compatible with high-altitude aircraft platforms such as the NASA ER-2s. The arbitrary 2-axis gimbal can perform conical and cross-track scanning, as well as fixed-beam staring. This compatibility with high-altitude platforms coupled with the flexible scanning configuration, opens up previously unavailable science opportunities for convection/precip/cloud science and co-flying with complementary instruments, as well as providing wider swath coverage for all science applications. By designing AESMIR to be compatible with these high-altitude platforms, we are also compatible with the NASA P-3, the NASA DC-8, C-130s and ground-based deployments. Thus AESMIR can provide low-, mid-, and high- altitude microwave imaging. Parallel filter banks allow AESMIR to simultaneously simulate the exact passbands of multiple satellite radiometers: SSM/I, TMI, AMSR, Windsat, SSMI/S, and the upcoming GPM/GMI and NPOESS/CMIS instruments --a unique capability among aircraft radiometers. An L-band option is also under development, again using the same scanner. With this option, simultaneous imaging from 1.4 to 89 GHz will be feasible. And, all receivers except the sounding channels will be configured for 4-Stokes polarimetric operation using high-speed digital

  10. Relationships between evaprorative fraction and remotely sensed vegetation index and microwave brightness temperature for semiarid rangelands

    NASA Technical Reports Server (NTRS)

    Kustas, W. P.; Schimugge, T. J.; Humes, K. S.; Jackson, T. J.; Parry, R.; Weltz, M. A.; Moran, M. S.

    1993-01-01

    Measurements of the microwave brightness temperature (TB) with the Pushbroom Microwave Radiometer (PBMR) over the Walnut Gulch Experiment Watershed were made on selected days during the MONSOON 90 field campaign. The PBMR is an L-band instrument (21-cm wavelength) that can provide estimates of near-surface soil moisture over a variety of surfaces. Aircraft observations in the visible and near-infrared wavelengths collected on selected days also were used to compute a vegetation index. Continuous micrometeorological measurements and daily soil moisture samples were obtained at eight locations during experimental period. Two sites were instrumented with time domain reflectometry probes to monitor the soil moisture profile. The fraction of available energy used for evapotranspiration was computed by taking the ratio of latent heat flux (LE) to the sum of net radiation (Rn) and soil heat flux (G). This ratio is commonly called the evaporative fraction (EF) and normally varies between 0 and 1 under daytime convective conditions with minimal advection. A wide range of environmental conditions existed during the field campaign, resulting in average EF values for the study area varying from 0.4 to 0.8 and values of TB ranging from 220 to 280 K. Comparison between measured TB and EF for the eight locations showed an inverse relationship. Other days were included in the analysis by estimating TB with the soil moisture data. Because transpiration from the vegetation is more strongly coupled to root zone soil moisture, significant scatter in this relationship existed at high values of TB or dry near-surface soil moisture conditions. The variation in EF under dry near-surface soil moisture conditions was correlated to the amount of vegetation cover estimated with a remotely sensed vegetation index. These findings indicate that information obtained from optical and microwave data can be used for quantifying the energy balance of semiarid areas. The microwave data can indicate

  11. A Comparison between Lightning Activity and Passive Microwave Measurements

    NASA Technical Reports Server (NTRS)

    Kevin, Driscoll T.; Hugh, Christian J.; Goodman, Steven J.

    1999-01-01

    A recent examination of data from the Lightning Imaging Sensor (LIS) and the TRMM Microwave Imager (TMI) suggests that storm with the highest frequency of lightning also possess the most pronounced microwave scattering signatures at 37 and 85 GHz. This study demonstrates a clear dependence between lightning and the passive microwave measurements, and accentuates how direct the relationship really is between cloud ice and lightning activity. In addition, the relationship between the quantity of ice content and the frequency of lightning (not just the presence of lightning) , is consistent throughout the seasons in a variety of regimes. Scatter plots will be presented which show the storm-averaged brightness temperatures as a function of the lightning density of the storms (L/Area) . In the 85 GHz and 37 GHz scatter plots, the brightness temperature is presented in the form Tb = k1 x log10(L/Area) + k2, where the slope of the regression, k1, is 58 for the 85 GHz relationship and 30.7 for the 37 GHz relationship. The regression for both these fits showed a correlation of 0.76 (r2 = 0.58), which is quite promising considering the simple procedure used to make the comparisons, which have not yet even been corrected for the view angle differences between the instruments, or the polarization corrections in the microwave imager.

  12. Connecting forest ecosystem and microwave backscatter models

    NASA Technical Reports Server (NTRS)

    Kasischke, Eric S.; Christensen, Norman L., Jr.

    1990-01-01

    A procedure is outlined to connect data obtained from active microwave remote sensing systems with forest ecosystem models. The hierarchy of forest ecosystem models is discussed, and the levels at which microwave remote sensing data can be used as inputs are identified. In addition, techniques to utilize forest ecosystem models to assist in the validation of theoretical microwave backscatter models are identified. Several examples to illustrate these connecting processes are presented.

  13. Crystallization and activation of silicon by microwave rapid annealing

    NASA Astrophysics Data System (ADS)

    Kimura, Shunsuke; Ota, Kosuke; Hasumi, Masahiko; Suzuki, Ayuta; Ushijima, Mitsuru; Sameshima, Toshiyuki

    2016-07-01

    A combination of the carbon-powder absorber with microwave irradiation is proposed as a rapid heat method. 2-μm-diameter carbon powders with a packing density of 0.08 effectively absorbed 2.45 GHz 1000-W-microwave and heated themselves to 1163 °C for 26 s. The present heat treatment recrystallized n-type crystalline silicon surfaces implanted with 1.0 × 10^{15}hbox {-cm}^{-2}-boron and phosphorus atoms with crystalline volume ratios of 0.99 and 0.93, respectively, by microwave irradiation at 1000 W for 20 s. Activation and carrier generation were simultaneously achieved with a sheet resistivity of 62 Ω / hbox {sq}. A high photo-induced-carrier effective lifetime of 1.0 × 10^{-4} s was also achieved. Typical electrical current-rectified characteristic and solar cell characteristic with an efficiency of 12.1 % under 100-mW/cm2-air-mass-1.5 illumination were obtained. Moreover, heat treatment with microwave irradiation at 1000 W for 22 s successfully crystallized silicon thin films with thicknesses ranging from 2.4 to 50 nm formed on quartz substrates. Nano-crystalline cluster structure with a high volume ratio of 50 % was formed in the 1.8-nm (initial 2.4-nm)-thick silicon films. Photoluminescence around 1.77 eV was observed for the 1.8-nm-thick silicon films annealed at 260 °C in 1.3 × 106-Pa-H2O-vapor for 3 h after the microwave heating.

  14. Global Mapping of Landscape Freeze-Thaw Status Using Spaceborne Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kimball, J. S.; McDonald, K. C.; Glassy, J.

    2009-12-01

    The freeze-thaw (F/T) status of the landscape is closely linked to surface energy budget and hydrological activity, vegetation phenology, terrestrial carbon budgets and land-atmosphere trace gas exchange. Spaceborne microwave radars and radiometers are ideally suited for global F/T monitoring due to insensitivity to signal degradation by atmospheric contamination, and solar illumination effects are uniquely capable of detecting the distinct change in landscape dielectric properties between predominantly frozen and thawed states, and provide a surrogate measure of a range of biophysical processes associated with the F/T signal, especially at high latitudes. In this study, we utilized multi-frequency satellite microwave radiometry from the Special Sensor Microwave Imager (SSM/I) and Advanced Microwave Scanning Radiometer for EOS (AMSR-E), and SeaWinds Ku-band scatterometry to map global patterns and daily variations in terrestrial F/T cycles using a temporal change detection based classification of daily brightness temperatures and radar backscatter involving seasonal threshold and temporal edge detection algorithms. We developed a global F/T classification domain by examining biophysical cold temperature constraints to vegetation growing seasons and land cover, open water and terrain heterogeneity. We evaluated daily F/T patterns from individual sensors using various band frequencies, polarizations and AM/PM overpass data. The F/T classification accuracy was assessed relative to surface air temperatures from WMO weather stations, regional climate patterns and terrain heterogeneity. The microwave sensors produced similar F/T spatial and temporal patterns, with mean annual classification accuracy of 85 (+/-5) % relative to in situ weather station records, while global F/T time series and corresponding annual frozen/unfrozen periods were quantified over a 20 year record. These results are being used to construct a consistent, systematic long-term global record of F

  15. Active and Passive Microwave Retrieval Algorithm for Hydrometeor Concentration Profiles: Application to the HAMP Instrument

    NASA Astrophysics Data System (ADS)

    Orlandi, E.; Mech, M.; Crewell, S.; Lammert, A.

    2012-12-01

    Clouds and precipitation play an important role in the atmospheric water cycle and radiation budget. Unfortunately, the understanding of the processes involved in cloud and precipitation formation and their description in global and regional models are still poor. To improve our understanding of these processes and to reduce model uncertainties, new observation and retrieval techniques are needed. The upcoming Global Precipitation Mission (GPM) provides a combination of a 36 GHz cloud radar and a suite of passive microwave instruments. In the retrieval development process for this and other upcoming missions, airborne platforms are a useful tool to test the algorithms exploiting the synergy of active and passive microwave instruments, and to validate satellite retrievals. In this respect HAMP (Microwave Package for HALO, the High Altitude Long Range aircraft), consisting of a 36 GHz Doppler cloud radar and a 26-channel radiometer, is an ideal test-bed. HAMP radiometers have frequencies along absorption lines (22, 60, 118 and 183 GHz) and in window regions, overlapping with those of AMSU A and B. HAMP will participate in early 2013 in the dedicated remote sensing HALO mission NARVAL (Next-generation Aircraft Remote-sensing for VALidation studies). During NARVAL, the HALO payload will include a water vapor lidar and drop sondes in addition to HAMP. The NARVAL campaign will thus be a excellent opportunity to test a newly developed retrieval algorithm, which exploits the synergy between passive and active microwave observations. In this work we present a Bayesian algorithm to retrieve precipitation rate, liquid and frozen hydrometeor concentration, as well as temperature and humidity profiles from the synergetic use of active and passive microwave nadir observations. Temperature and humidity are derived solely from passive radiometer measurements while the combined cloud radar and radiometer observations are used to retrieve hydrometeor concentration profiles. Lidar

  16. AMISS - Active and passive MIcrowaves for Security and Subsurface imaging

    NASA Astrophysics Data System (ADS)

    Soldovieri, Francesco; Slob, Evert; Turk, Ahmet Serdar; Crocco, Lorenzo; Catapano, Ilaria; Di Matteo, Francesca

    2013-04-01

    The FP7-IRSES project AMISS - Active and passive MIcrowaves for Security and Subsurface imaging is based on a well-combined network among research institutions of EU, Associate and Third Countries (National Research Council of Italy - Italy, Technische Universiteit Delft - The Netherlands, Yildiz Technical University - Turkey, Bauman Moscow State Technical University - Russia, Usikov Institute for Radio-physics and Electronics and State Research Centre of Superconductive Radioelectronics "Iceberg" - Ukraine and University of Sao Paulo - Brazil) with the aims of achieving scientific advances in the framework of microwave and millimeter imaging systems and techniques for security and safety social issues. In particular, the involved partners are leaders in the scientific areas of passive and active imaging and are sharing their complementary knowledge to address two main research lines. The first one regards the design, characterization and performance evaluation of new passive and active microwave devices, sensors and measurement set-ups able to mitigate clutter and increase information content. The second line faces the requirements to make State-of-the-Art processing tools compliant with the instrumentations developed in the first line, suitable to work in electromagnetically complex scenarios and able to exploit the unexplored possibilities offered by new instrumentations. The main goals of the project are: 1) Development/improvement and characterization of new sensors and systems for active and passive microwave imaging; 2) Set up, analysis and validation of state of art/novel data processing approach for GPR in critical infrastructure and subsurface imaging; 3) Integration of state of art and novel imaging hardware and characterization approaches to tackle realistic situations in security, safety and subsurface prospecting applications; 4) Development and feasibility study of bio-radar technology (system and data processing) for vital signs detection and

  17. Annual South American forest loss estimates based on passive microwave remote sensing (1990-2010)

    NASA Astrophysics Data System (ADS)

    van Marle, M. J. E.; van der Werf, G. R.; de Jeu, R. A. M.; Liu, Y. Y.

    2015-07-01

    Consistent forest loss estimates are important to understand the role of forest loss and deforestation in the global carbon cycle, for biodiversity studies, and to estimate the mitigation potential of reducing deforestation. To date, most studies have relied on optical satellite data and new efforts have greatly improved our quantitative knowledge on forest dynamics. However, most of these studies yield results for only a relatively short time period or are limited to certain countries. We have quantified large-scale forest losses over a 21 year period (1990-2010) in the tropical biomes of South America using remotely sensed vegetation optical depth (VOD). This passive microwave satellite-based indicator of vegetation water content and vegetation density has a much coarser spatial resolution than optical but its temporal resolution is higher and VOD is not impacted by aerosols and cloud cover. We used the merged VOD product of the Advanced Microwave Scanning Radiometer (AMSR-E) and Special Sensor Microwave Imager (SSM/I) observations, and developed a change detection algorithm to quantify spatial and temporal variations in forest loss dynamics. Our results compared favorably to the newly developed Global Forest Change (GFC) maps based on Landsat data and available for the 2001 onwards period (r2 = 0.90 when comparing annual country-level estimates), which allowed us to convert our results to forest loss area and compute these from 1990 onwards. We found that South American forest exhibited substantial interannual variability without a clear trend during the 1990s, but increased from 2000 until 2004. After 2004, forest loss decreased again, except for two smaller peaks in 2007 and 2010. For a large part, these trends were driven by changes in Brazil, which was responsible for 56 % of the total South American forest loss over our study period according to our results. One of the key findings of our study is that while forest losses decreased in Brazil after 2005

  18. Annual South American forest loss estimates based on passive microwave remote sensing (1990-2010)

    NASA Astrophysics Data System (ADS)

    van Marle, M. J. E.; van der Werf, G. R.; de Jeu, R. A. M.; Liu, Y. Y.

    2016-02-01

    Consistent forest loss estimates are important to understand the role of forest loss and deforestation in the global carbon cycle, for biodiversity studies, and to estimate the mitigation potential of reducing deforestation. To date, most studies have relied on optical satellite data and new efforts have greatly improved our quantitative knowledge on forest dynamics. However, most of these studies yield results for only a relatively short time period or are limited to certain countries. We have quantified large-scale forest loss over a 21-year period (1990-2010) in the tropical biomes of South America using remotely sensed vegetation optical depth (VOD). This passive microwave satellite-based indicator of vegetation water content and vegetation density has a much coarser spatial resolution than optical data but its temporal resolution is higher and VOD is not impacted by aerosols and cloud cover. We used the merged VOD product of the Advanced Microwave Scanning Radiometer (AMSR-E) and Special Sensor Microwave Imager (SSM/I) observations, and developed a change detection algorithm to quantify spatial and temporal variations in forest loss dynamics. Our results compared reasonably well with the newly developed Landsat-based Global Forest Change (GFC) maps, available for the 2001 onwards period (r2 = 0.90 when comparing annual country-level estimates). This allowed us to convert our identified changes in VOD to forest loss area and compute these from 1990 onwards. We also compared these calibrated results to PRODES (r2 = 0.60 when comparing annual state-level estimates). We found that South American forest exhibited substantial interannual variability without a clear trend during the 1990s, but increased from 2000 until 2004. After 2004, forest loss decreased again, except for two smaller peaks in 2007 and 2010. For a large part, these trends were driven by changes in Brazil, which was responsible for 56 % of the total South American forest loss area over our study

  19. Evaluation of a microwave and infrared human-presence sensing system for agricultural equipment.

    PubMed

    Shutske, J M; Gilbert, W; Chaplin, J

    2001-11-01

    The potential use of electronic safety sensors to protect operators from agricultural equipment with rotating hazards has been identified and discussed as a possible means to prevent traumatic entanglement injury. A multi-sensor human-presence sensing system to protect persons approaching a rotating PTO shaft powering a stationary implement was developed using commercially available, passive infrared and microwave sensors. A control and data acquisition system was designed and constructed to evaluate sensor performance and response. The sensor system performed well during 822 warm weather test passes in which a person approached the potentially hazardous area near the drawbar and PTO/IID located between an IH 986 test tractor and a self-unloading forage wagon. During the 822 test passes, there were no false alarms and no misses. Operators approached the hazard space walking from 92 to 227 cm/second. During tests, the sensing system yielded warning times generally between 0.5 and 1.0 seconds, providing an estimate of the time available to accomplish machine shutdown or operator warnings. Additional cold weather tests caused the control and data acquisition hardware to function erratically. This work suggests that multi-sensor human detection systems have the potential to reduce false alarms through redundancy when more than one sensor is required to detect a person before the system signals a "detect" condition. However, the use of multiple, redundant sensors also increases the potential for a "miss." Further work is needed to determine whether these types of sensor can yield timely enough information to prevent injury via mechanical shutdown or operator warnings. PMID:11787754

  20. Measurement of heart rate variability and stress evaluation by using microwave reflectometric vital signal sensing

    NASA Astrophysics Data System (ADS)

    Nagae, Daisuke; Mase, Atsushi

    2010-09-01

    In this paper, we present two robust signal processing techniques for stress evaluation using a microwave reflectometric cardiopulmonary sensing instrument. These techniques enable the heart rate variability (HRV) to be recovered from measurements of body-surface dynamic motion, which is subsequently used for the stress evaluation. Specifically, two novel elements are introduced: one is a reconfiguration of the HRV from the cross-correlation function between a measurement signal and a template signal which is constructed by averaging periodic component over a measurement time. The other is a reconstruction of the HRV from the time variation of the heartbeat frequency; this is evaluated by a repetition of the maximum entropy method. These two signal processing techniques accomplish the reconstruction of the HRV, though they are completely different algorithms. For validations of our model, an experimental setup is presented and several sets of experimental data are analyzed using the two proposed signal processing techniques, which are subsequently used for the stress evaluation. The results presented herein are consistent with electrocardiogram data.

  1. Microwave Remote Sensing of Soil Moisture for Estimation of Soil Properties

    NASA Technical Reports Server (NTRS)

    Mattikalli, Nandish M.; Engman, Edwin T.; Jackson, Thomas J.

    1997-01-01

    Surface soil moisture dynamics was derived using microwave remote sensing, and employed to estimate soil physical and hydraulic properties. The L-band ESTAR radiometer was employed in an airborne campaign over the Little Washita watershed, Oklahoma during June 10-18, 1992. Brightness temperature (TB) data were employed in a soil moisture inversion algorithm which corrected for vegetation and soil effects. Analyses of spatial TB and soil moisture dynamics during the dry-down period revealed a direct relationship between changes in TB, soil moisture and soil texture. Extensive regression analyses were carried out which yielded statistically significant quantitative relationships between ratio of percent sand to percent clay (RSC, a term derived to quantify soil texture) and saturated hydraulic conductivity (Ksat) in terms of change components of TB and surface soil moisture. Validation of results indicated that both RSC and Ksat can be estimated with reasonable accuracy. These findings have potential applications for deriving spatial distributions of RSC and Ksat over large areas.

  2. A mathematical characterization of vegetation effect on microwave remote sensing from the Earth

    NASA Technical Reports Server (NTRS)

    Choe, Y.; Tsang, L.

    1983-01-01

    In passive microwave remote sensing of the earth, a theoretical model that utilizes the radiative transfer equations was developed to account for the volume scattering effects of the vegetation canopy. Vegetation canopies such as alfalfa, sorghum, and corn are simulated by a layer of ellipsoidal scatterers and cylindrical structures. The ellipsoidal scatterers represent the leaves of vegetation and are randomly positioned and oriented. The orientation of ellipsoids is characterized by a probability density function of Eulerian angles of rotation. The cylindrical structures represent the stalks of vegetation and their radii are assumed to be much smaller than their lengths. The underlying soil is represented by a half-space medium with a homogeneous permittivity and uniform temperature profile. The radiative transfer quations are solved by a numerical method using a Gaussian quadrature formula to compute both the vertical and horizontal polarized brightness temperature as a function of observation angle. The theory was applied to the interpretation of experimental data obtained from sorghum covered fields near College Station, Texas.

  3. Passive/Active Microwave Soil Moisture Disaggregation Using SMAPVEX12 Data

    NASA Astrophysics Data System (ADS)

    Fang, B.; Lakshmi, V.; Bindlish, R.; Jackson, T. J.; Colliander, A.

    2015-12-01

    The SMAPVEX12 experiment was conducted during June-July 2012 in Manitoba, Canada with the goal of collecting remote sensing data and ground measurements for the development and testing of soil moisture retrieval algorithms under different vegetation and soil conditions for the SMAP (Soil Moisture Active Passive) satellite launched in January 2015. The aircraft based soil moisture data provided by the passive/active microwave sensor PALS (Passive and Active L and S band System) has a nominal spatial resolution of 1500 m. In this study, a change detection algorithm is used for disaggregation of coarse passive microwave soil moisture retrievals with radar backscatter coefficients obtained with the higher spatial resolution UAVSAR (Unmanned Air Vehicle Synthetic Aperture Radar). The accuracy of the disaggregated change in soil moisture was evaluated using ground based soil moisture measurements. Results show that the disaggregation products are well correlated to in situ measurements. Based on the R2, the highest resolution disaggregated product at 5 m exhibits soil moisture heterogeneity that reflects the distribution of the crops. The difference of spatial standard deviation between the disaggregated and in situ soil moisture ranges from <0.001-0.131 m3/m3 also proves the spatial capability of the change detection algorithm at 5 m scale.

  4. Active structural waveguide for sensing application

    NASA Astrophysics Data System (ADS)

    Czajkowski, Karol; Kochanowicz, Marcin; Zmojda, Jacek; Miluski, Piotr; Dorosz, Dominik

    2014-05-01

    In the article a microstructural active optical fiber for sensing application was presented. Construction consists of three hexagonal rings and a core made of SiO2 - Al2O3 - Sb2O3 glass co-doped with 1Yb2O3/0.1Tm2O3 [mol%]. Developed optical fiber is characterized by upconversion luminescence (λp=980nm) at 480nm (Tm3+: 1G4→3H6) and 650 nm (Tm3+ : 1G4→3F4). Population of thulium levels was attained in result of the Yb 3+→Tm3+ upconversion energy transfer. Sensing application of elaborated active photonic structure was presented on the example of aqueous fluorescein solution. Fabricated microstructural optical fiber enables to measure of the fluorescein solutions with the concentration of (0.25 - 5.42)·10-4 [mol%]. Sensitivity of the elaborated measurement setup is 1.51·104 [1/mol%].

  5. Dynamics of Active Sensing and Perceptual Selection

    PubMed Central

    Schroeder, Charles E; Wilson, Donald A.; Radman, Thomas; Scharfman, Helen; Lakatos, Peter

    2010-01-01

    Sensory processing is often regarded as a passive process in which a biological sensors like photo- and mechanoreceptors transducer physical energy into a neural code. Recent findings, however, suggest that: 1) most sensory processing is active, and largely determined by motor/attentional sampling routines, 2) due to rhythmicity in the motor routine, as well as to its entrainment of ambient rhythms in sensory regions, sensory inflow tends to be rhythmic, and 3) attentional manipulation of rhythms in sensory pathways is instrumental to perceptual selection. These observations outline the essentials of an Active Sensing paradigm, and argue for increased emphasis on the study of sensory processes as specific to the dynamic motor/attentional context in which inputs are acquired. PMID:20307966

  6. Hierarchical curiosity loops and active sensing.

    PubMed

    Gordon, Goren; Ahissar, Ehud

    2012-08-01

    A curious agent acts so as to optimize its learning about itself and its environment, without external supervision. We present a model of hierarchical curiosity loops for such an autonomous active learning agent, whereby each loop selects the optimal action that maximizes the agent's learning of sensory-motor correlations. The model is based on rewarding the learner's prediction errors in an actor-critic reinforcement learning (RL) paradigm. Hierarchy is achieved by utilizing previously learned motor-sensory mapping, which enables the learning of other mappings, thus increasing the extent and diversity of knowledge and skills. We demonstrate the relevance of this architecture to active sensing using the well-studied vibrissae (whiskers) system, where rodents acquire sensory information by virtue of repeated whisker movements. We show that hierarchical curiosity loops starting from optimally learning the internal models of whisker motion and then extending to object localization result in free-air whisking and object palpation, respectively. PMID:22386787

  7. Dynamics of Active Sensing and perceptual selection.

    PubMed

    Schroeder, Charles E; Wilson, Donald A; Radman, Thomas; Scharfman, Helen; Lakatos, Peter

    2010-04-01

    Sensory processing is often regarded as a passive process in which biological receptors like photoreceptors and mechanoreceptors transduce physical energy into a neural code. Recent findings, however, suggest that: first, most sensory processing is active, and largely determined by motor/attentional sampling routines; second, owing to rhythmicity in the motor routine, as well as to its entrainment of ambient rhythms in sensory regions, sensory inflow tends to be rhythmic; third, attentional manipulation of rhythms in sensory pathways is instrumental to perceptual selection. These observations outline the essentials of an Active Sensing paradigm, and argue for increased emphasis on the study of sensory processes as specific to the dynamic motor/attentional context in which inputs are acquired. PMID:20307966

  8. A monostatic microwave transmission experiment for line integrated precipitation and humidity remote sensing

    NASA Astrophysics Data System (ADS)

    Chwala, Christian; Kunstmann, Harald; Hipp, Susanne; Siart, Uwe

    2014-07-01

    Near-surface water vapor and precipitation are central hydrometeorological observables which are still difficult to quantify accurately above the point scale. Both play an important role in modeling and remote sensing of the hydrologic cycle. We present details on the development of a new microwave transmission experiment that is capable of providing line integrated estimates of both humidity and precipitation near the surface. The system is located at a hydrometeorological test site (TERENO-prealpine) in Southern Germany. Path length is kept short at 660 m to minimize the likelihood of different precipitation types and intensities along the path. It uses a monostatic configuration with a combined transmitter/receiver unit and a 70 cm trihedral reflector. The transmitter/receiver unit simultaneously operates at 22.235 GHz and 34.8 GHz with a pulse repetition rate of 25 kHz and alternating horizontal and vertical polarization, which enable the analysis of the impact of the changing drop size distribution on the rain rate retrieval. Due to the coherence and the high phase stability of the system, it allows for a sensitive observation of the propagation phase delay. Thereof, time series of line integrated refractivity can be determined. This proxy is then post-processed to absolute humidity and compared to station observations. We present the design of the system and show an analysis of selected periods for both, precipitation and humidity observations. The theoretically expected dependence of attenuation and differential attenuation on the DSD was reproduced with experimental data. A decreased performance was observed when using a fixed A-R power law. Humidity data derived from the phase delay measurement showed good agreement with in situ measurements.

  9. Ground-based microwave remote sensing of temperature inversions in the Bergen valley, Norway

    NASA Astrophysics Data System (ADS)

    Wolf, Tobias; Esau, Igor; Reuder, Joachim

    2014-05-01

    The temperature profiles in the urbanized Bergen valley, Norway, are characterized by wintertime temperature inversions, which have a strong impact on the surface layer air quality in the city. We present the results from two years of vertical temperature profile measurements obtained with the ground-based microwave temperature profiler MTP-5HE and show the advantages of ground-based remote sensing with this instrument for the monitoring of atmospheric temperature inversions. From a subset of the final, filtered dataset we found that the mean difference between temperatures measured with the MTP-5HE and an automatic meteorological station (AMS) on a nearby mountain was as low as -0.03 ± 0.78 K during inversion free conditions and -0.06 ± 0.71 K during ground-based temperature inversions. The only selection criterion for this subset was a wind speed of more than 5 m/s and to ensure comparability between the location of the AMS and the central valley atmosphere. We found two regimes of ground-based inversions: Non-persistent inversions lasting shorter than 2 hours that are mostly thinner than 100 m and more persistent inversions often reaching 270 m above sea level. The height of the shorter inversions was consistent with the maximum height of inversions found in a previous study based on tethersonde measurements. Ground-based inversions mostly occurred during situations characterized by weak winds in the ERA-Interim reanalysis, to a large degree independent from wind direction. A distinct south-easterly tail in the ERA-Interim wind distribution with wind speeds as high as 16 m/s might have been connected to a wake effect from a nearby mountain. The strong channeling effect within the valley that was also found in previous studies was evident. The ground-based remote sensing was particularly useful for the monitoring of elevated temperature inversions between 170 m and 720 m above sea level. This kind of inversions has not been observed in this valley before. They

  10. Regional Characterization of Landscape Freeze/Thaw Transitions Using Spaceborne Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Podest, E.; McDonald, K. C.; Kimball, J. S.

    2005-12-01

    Boreal forests contain much of the Earth's terrestrial carbon storage in vegetation and seasonally frozen and permafrost soils. The annual freeze/thaw cycle drives the length of the growing season in these landscapes and is a major factor determining annual productivity and associated CO2 exchange with the atmosphere. Satellite microwave remote sensing is sensitive to landscape freeze/thaw state and is an effective tool for this purpose since large inaccessible areas can be monitored regardless of atmospheric conditions or solar illumination. We examined the spatial and temporal characteristics of the seasonal freeze/thaw transition across Alaska and Canada using time series spaceborne radar backscatter measurements from ERS (C-band, 100m, VV-polarization) and JERS (L-band, 100m, HH-polarization), and SeaWinds on QuikSCAT (Ku-band, 25km, HH and VV polarization) sensors. We examined remote sensing based freeze/thaw dynamics in relation to terrain, elevation and land cover complexity, and the relative effects of fire disturbance on these processes, as well as sensor frequency and spatial scale on sensor retrieval accuracy. All sensors examined were sensitive to landscape freeze/thaw state transitions, though sensitivity varies by sensor frequency and landscape component (e.g. vegetation, snow). The study regions analyzed exhibit high spatial heterogeneity in freeze/thaw dynamics associated with complex topography, surface water and land cover composition. Freeze/thaw spatial heterogeneity was detected at high (100m) resolution data. The backscatter freeze-thaw response was inversely proportional to elevation, with the seasonal thaw wave initiating at lower elevations and extending to higher elevations. The observed radar thaw signal also varied by aspect and land cover, with south-facing and deciduous forest sites thawing earlier relative to north-facing and coniferous forest sites. Relatively coarse resolution (25km) SeaWinds data provide for daily assessment of

  11. Degradation and dechlorination of pentachlorophenol by microwave-activated persulfate.

    PubMed

    Qi, Chengdu; Liu, Xitao; Zhao, Wei; Lin, Chunye; Ma, Jun; Shi, Wenxiao; Sun, Qu; Xiao, Hao

    2015-03-01

    The degradation performance of pentachlorophenol (PCP) by the microwave-activated persulfate (MW/PS) process was investigated in this study. The results indicated that degradation efficiency of PCP in the MW/PS process followed pseudo-first-order kinetics, and compared with conventional heating, microwave heating has a special effect of increasing the reaction rate and reducing the process time. A higher persulfate concentration and reaction temperature accelerated the PCP degradation rate. Meanwhile, increasing the pH value and ionic strength of the phosphate buffer slowed down the degradation rate. The addition of ethanol and tert-butyl alcohol as hydroxyl radical and sulfate radical scavengers proved that the sulfate radicals were the dominant active species in the MW/PS process. Gas chromatography-mass spectrometry (GC-MS) was employed to identify the intermediate products, and then a plausible degradation pathway involving dechlorination, hydrolysis, and mineralization was proposed. The acute toxicity of PCP, as tested with Photobacterium phosphoreum, Vibrio fischeri, and Vibrio qinghaiensis, was negated quickly during the MW/PS process, which was in agreement with the nearly complete mineralization of PCP. These results showed that the MW/PS process could achieve a high mineralization level in a short time, which provided an efficient way for PCP elimination from wastewater. PMID:25328098

  12. Microwave sensing of moisture content and bulk density in flowing grain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Moisture content and bulk density were determined from measurement of the dielectric properties of flowing wheat kernels at a single microwave frequency (5.8 GHz). The measuring system consisted of two high-gain microwave patch antennas mounted on opposite sides of rectangular chute and connected to...

  13. NASA's Potential Contributions to Avalanche Forecasting Using Active and Passive Microwave Measurements

    NASA Technical Reports Server (NTRS)

    Blonski, Slawomir

    2007-01-01

    This Candidate Solution is based on using active and passive microwave measurements acquired from NASA satellites to improve USDA (U.S. Department of Agriculture) Forest Service forecasting of avalanche danger. Regional Avalanche Centers prepare avalanche forecasts using ground measurements of snowpack and mountain weather conditions. In this Solution, range of the in situ observations is extended by adding remote sensing measurements of snow depth, snow water equivalent, and snowfall rate acquired by satellite missions that include Aqua, CloudSat, future GPM (Global Precipitation Measurement), and the proposed SCLP (Snow and Cold Land Processes). Measurements of snowpack conditions and time evolution are improved by combining the in situ and satellite observations with a snow model. Recurring snow observations from NASA satellites increase accuracy of avalanche forecasting, which helps the public and the managers of public facilities make better avalanche safety decisions.

  14. Microwave-assisted rapid synthesis of luminescent gold nanoclusters for sensing Hg2+ in living cells using fluorescence imaging.

    PubMed

    Shang, Li; Yang, Linxiao; Stockmar, Florian; Popescu, Radian; Trouillet, Vanessa; Bruns, Michael; Gerthsen, Dagmar; Nienhaus, G Ulrich

    2012-07-21

    A microwave-assisted strategy for synthesizing dihydrolipoic acid (DHLA) capped fluorescent gold nanoclusters (AuNCs) has been developed. Irradiation with microwaves during synthesis enhanced the fluorescence quantum yield (QY) of AuNCs by about five-fold and shortened the reaction time from hours to several minutes. The as-synthesized DHLA-AuNCs possessed bright near-infrared fluorescence (QY: 2.9%), ultrasmall hydrodynamic diameter (3.3 nm), good colloidal stability over the physiologically relevant pH range of 5-10 as well as low cytotoxicity toward HeLa cells. Moreover, these DHLA-AuNCs were capable of sensing Hg(2+) through the specific interaction between Hg(2+) and Au(+) on the surface of AuNCs; the limit of detection (LOD) was 0.5 nM. A potential application in imaging intracellular Hg(2+) in HeLa cells was demonstrated by using spinning disc confocal microscopy. PMID:22460520

  15. Spaceborne Microwave Instrument for High Resolution Remote Sensing of the Earth's Surface Using a Large-Aperture Mesh Antenna

    NASA Technical Reports Server (NTRS)

    Njoku, E.; Wilson, W.; Yueh, S.; Freeland, R.; Helms, R.; Edelstein, W.; Sadowy, G.; Farra, D.; West, R.; Oxnevad, K.

    2001-01-01

    This report describes a two-year study of a large-aperture, lightweight, deployable mesh antenna system for radiometer and radar remote sensing of the Earth from space. The study focused specifically on an instrument to measure ocean salinity and Soil moisture. Measurements of ocean salinity and soil moisture are of critical . importance in improving knowledge and prediction of key ocean and land surface processes, but are not currently obtainable from space. A mission using this instrument would be the first demonstration of deployable mesh antenna technology for remote sensing and could lead to potential applications in other remote sensing disciplines that require high spatial resolution measurements. The study concept features a rotating 6-m-diameter deployable mesh antenna, with radiometer and radar sensors, to measure microwave emission and backscatter from the Earth's surface. The sensors operate at L and S bands, with multiple polarizations and a constant look angle, scanning across a wide swath. The study included detailed analyses of science requirements, reflector and feedhorn design and performance, microwave emissivity measurements of mesh samples, design and test of lightweight radar electronic., launch vehicle accommodations, rotational dynamics simulations, and an analysis of attitude control issues associated with the antenna and spacecraft, The goal of the study was to advance the technology readiness of the overall concept to a level appropriate for an Earth science emission.

  16. Use of in situ and modelled soil moisture estimates to evaluate microwave remotely sensed products in southwestern France

    NASA Astrophysics Data System (ADS)

    Albergel, C.; Rüdiger, C.; Calvet, J.-C.; Carrer, D.; Pellarin, T.

    2009-04-01

    A long term data acquisition effort of profile soil moisture is currently underway at 13 automatic weather stations located in southwestern France. This ground network was developed in order to validate remote sensing and model soil moisture estimates. As a first step, an exponential filter and its recursive formulation were used in order to estimate the Soil Water Index (SWI) from in-situ surface soil moisture measurements (SSM, at a depth of 5 cm) and comparing those to observations at 30cm. Most often than not, the estimated SWI correlates well with the in-situ measurements. The only parameter required is a characteristic time length T, where a single value of T=6 days allows to estimate soil moisture at a depth of 30cm from observations at 5cm for the whole group of station. A synthetic soil moisture data set covering continental France is also used. From this data set the added value of using the filter to estimate the SWI is demonstrated. Also, soil moisture measured in-situ at 5 cm is used to evaluate the normalized SSM estimates derived from coarse-resolution (25 km) active microwave data of the ASCAT scatterometer instrument (onboard METOP), issued by EUMETSAT, for a period of 6 months (April-September) in 2007. In order to remove the seasonal trend, the satellite and the in-situ time series soil moisture observations are transformed into normalised anomalies. Nine stations present significant correlation levels. For two stations, a significant correlation is obtained when considering only part of the ASCAT data. The soil moisture measured in-situ at those stations, at 30 cm, is used to estimate the characteristic time length (T) of an exponential filter applied to the ASCAT product. The best correlation between a soil water index derived from ASCAT and the in-situ soil moisture observations at 30 cm is obtained with a T-value of 14 days.

  17. Remote sensing of snow properties by passive microwave radiometry: GSFC truck experiment

    NASA Technical Reports Server (NTRS)

    Chang, A. T. C.; Rango, A.; Shiue, J.

    1980-01-01

    Recent results indicate that microwave radiometry has the potential for inferring the snow depth and water equivalent information from snowpacks. In order to assess this potential for determining the water equivalent of a snowpack, it is necessary to understand the microwave emission and scattering behavior of the snow at various wavelengths under carefully controlled conditions. Truck-mounted microwave instrumentation was used to study the microwave characteristics of the snowpack in the Colorado Rocky Mountain region during the winters of 1977 to 78 and 7978 to 79. The spectral signatures of C, X, K sub u, and K sub a band radiometers with dual polarization were used, together with measurements of snowpack density, temperature an ram profiles, liquid water content, and rough characterization of the crystal sizes. These data compared favorably with calculated results based on recent microscopic scattering models.

  18. Sensors and methods for weather-independent remote sensing with microwaves

    NASA Technical Reports Server (NTRS)

    Keydel, W.

    1981-01-01

    Sensors and methods of radar and microwave radiometry which operate in the millimeter wave range are discussed. The properties of electromagnetic waves are discussed as well as the resolution capacity and measurement accuracy of sensor systems.

  19. Study of MARS for Explorations of Landing Sites Using Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Calla, O. P. N.

    2015-10-01

    Highlight the role of Microwave Sensors in exploration of Mars and the type of Sensors that could be used for providing information about Mars and give some details of the laboratory experiments using terrestrial analog of martian soil.

  20. Cross-Product Comparison of Multiple Resolution Microwave Remote Sensing Data Sets Supporting Global Mapping of Inundated Wetlands

    NASA Astrophysics Data System (ADS)

    Podest, E.; Schroeder, R.; McDonald, K. C.; Pinto, N.; Willacy, K.; Whitcomb, J.; Moghaddam, M.; Hess, L. L.; Zimmermann, R.

    2010-12-01

    Inundated vegetation and open water bodies are common features across the landscape and exert major impacts on hydrologic processes and surface-atmosphere carbon exchange. Their carbon dioxide and methane emissions can have a large impact on global climate. It is therefore of great importance to assess their spatial extent and temporal variations in order to improve upon carbon balance estimates. Despite their importance in the global cycling of carbon and water and climate forecasting, they remain poorly characterized and modeled, primarily because of the scarcity of suitable regional-to-global remote sensing data for characterizing wetlands distribution and dynamics. Spaceborne synthetic aperture radar (SAR) offers an effective tool for characterizing these ecosystems since it is particularly sensitive to surface water and to vegetation structure, and it allows monitoring large inaccessible areas on a temporal basis regardless of atmospheric conditions or solar illumination. We are assembling a multi-year Earth System Data Record (ESDR) of global inundated wetlands to facilitate investigations on their role in climate, biogeochemistry, hydrology, and biodiversity. The ESDR is comprised of (1) fine-resolution (100m) maps of wetland extent, vegetation type, and seasonal inundation extent, derived from L-band SAR data from the Advanced Land Observing Satellite (ALOS) Phased Array L-Band SAR (PALSAR) and the Japanese Earth Resources Satellite (JERS) SAR, for continental-scale areas covering crucial wetland regions, and (2) global multi-temporal mappings of inundation extent at 25 km resolution derived from data sets from combined passive and active microwave remote sensing instruments (AMSR-E, QuikSCAT). We present a comparative analysis of the high-resolution SAR-based data sets and the coarse resolution inundation data sets for wetland ecosystems in the Amazonian tropics and the northern high latitudes of Alaska, Canada, and Eurasia. We compare information content

  1. Photonic compressive sensing for analog-to-information conversion with a delay-line based microwave photonic filter

    NASA Astrophysics Data System (ADS)

    Zhu, Zhijing; Chi, Hao; Jin, Tao; Zheng, Shilie; Jin, Xiaofeng; Zhang, Xianmin

    2016-07-01

    Compressive sensing (CS) in the photonic domain is highly promising for analog-to-information conversion of sparse signals due to its potential capability of high input bandwidth and digitization with sub-Nyquist sampling. In this paper, we suggest that the concept of delay-line based microwave photonic filter be used in photonic CS to realize the low-pass filtering (LPF) function which is required in CS. A microwave photonic filter (MPF) with a dispersive element and fiber delay lines is applied in photonic CS to achieve better performance and flexibility. In the approach, the input radio-frequency signal and the pseudorandom bit sequence (PRBS) are modulated on a multi-wavelength optical carrier and propagate through a dispersive element. The modulated optical signal is split into multiple channels with tunable delay lines. The multiple wavelengths, dispersive element and multiple channels constitute a reconfigurable low-pass microwave filter. Experiment and simulations are presented to demonstrate the feasibility and potentials of this approach.

  2. New potentially active pyrazinamide derivatives synthesized under microwave conditions.

    PubMed

    Jandourek, Ondrej; Dolezal, Martin; Kunes, Jiri; Kubicek, Vladimir; Paterova, Pavla; Pesko, Matus; Buchta, Vladimir; Kralova, Katarina; Zitko, Jan

    2014-01-01

    A series of 18 N-alkyl substituted 3-aminopyrazine-2-carboxamides was prepared in this work according to previously experimentally set and proven conditions using microwave assisted synthesis methodology. This approach for the aminodehalogenation reaction was chosen due to higher yields and shorter reaction times compared to organic reactions with conventional heating. Antimycobacterial, antibacterial, antifungal and photosynthetic electron transport (PET) inhibiting in vitro activities of these compounds were investigated. Experiments for the determination of lipophilicity were also performed. Only a small number of substances with alicyclic side chain showed activity against fungi which was the same or higher than standards and the biological efficacy of the compounds increased with rising lipophilicity. Nine pyrazinamide derivatives also inhibited PET in spinach chloroplasts and the IC50 values of these compounds varied in the range from 14.3 to 1590.0 μmol/L. The inhibitory activity was connected not only with the lipophilicity, but also with the presence of secondary amine fragment bounded to the pyrazine ring. Structure-activity relationships are discussed as well. PMID:24995919

  3. Observations of cloud liquid water path over oceans: Optical and microwave remote sensing methods

    NASA Technical Reports Server (NTRS)

    Lin, Bing; Rossow, William B.

    1994-01-01

    Published estimates of cloud liquid water path (LWP) from satellite-measured microwave radiation show little agreement, even about the relative magnitudes of LWP in the tropics and midlatitudes. To understand these differences and to obtain more reliable estimate, optical and microwave LWP retrieval methods are compared using the International Satellite Cloud Climatology Project (ISCCP) and special sensor microwave/imager (SSM/I) data. Errors in microwave LWP retrieval associated with uncertainties in surface, atmosphere, and cloud properties are assessed. Sea surface temperature may not produce great LWP errors, if accurate contemporaneous measurements are used in the retrieval. An uncertainty of estimated near-surface wind speed as high as 2 m/s produces uncertainty in LWP of about 5 mg/sq cm. Cloud liquid water temperature has only a small effect on LWP retrievals (rms errors less than 2 mg/sq cm), if errors in the temperature are less than 5 C; however, such errors can produce spurious variations of LWP with latitude and season. Errors in atmospheric column water vapor (CWV) are strongly coupled with errors in LWP (for some retrieval methods) causing errors as large as 30 mg/sq cm. Because microwave radiation is much less sensitive to clouds with small LWP (less than 7 mg/sq cm) than visible wavelength radiation, the microwave results are very sensitive to the process used to separate clear and cloudy conditions. Different cloud detection sensitivities in different microwave retrieval methods bias estimated LWP values. Comparing ISCCP and SSM/I LWPs, we find that the two estimated values are consistent in global, zonal, and regional means for warm, nonprecipitating clouds, which have average LWP values of about 5 mg/sq cm and occur much more frequently than precipitating clouds. Ice water path (IWP) can be roughly estimated from the differences between ISCCP total water path and SSM/I LWP for cold, nonprecipitating clouds. IWP in the winter hemisphere is about

  4. Recent improvements in retrieving near-surface air temperature and humidity using microwave remote sensing (Invited)

    NASA Astrophysics Data System (ADS)

    Roberts, J. B.

    2010-12-01

    Detailed studies of the energy and water cycles require accurate estimation of the turbulent fluxes of moisture and heat across the atmosphere-ocean interface at regional to basin scale. Providing estimates of these latent and sensible heat fluxes over the global ocean necessitates the use of satellite or reanalysis-based estimates of near surface variables. Recent studies have shown that errors in the surface (10 meter) estimates of humidity and temperature are currently the largest sources of uncertainty in the production of turbulent fluxes from satellite observations. Therefore, emphasis has been placed on reducing the systematic errors in the retrieval of these parameters from microwave radiometers. This study discusses recent improvements in the retrieval of air temperature and humidity through improvements in the choice of algorithms (linear vs. nonlinear) and the choice of microwave sensors. Particular focus is placed on improvements using a neural network approach with a single sensor (Special Sensor Microwave/Imager) and the use of combined sensors from the NASA AQUA satellite platform. The latter algorithm utilizes the unique sampling available on AQUA from the Advanced Microwave Scanning Radiometer (AMSR-E) and the Advanced Microwave Sounding Unit (AMSU-A). Current estimates of uncertainty in the near-surface humidity and temperature from single and multi-sensor approaches are discussed and used to estimate errors in the turbulent fluxes.

  5. Recent Improvements in Retrieving Near-Surface Air Temperature and Humidity Using Microwave Remote Sensing

    NASA Technical Reports Server (NTRS)

    Roberts, J. Brent

    2010-01-01

    Detailed studies of the energy and water cycles require accurate estimation of the turbulent fluxes of moisture and heat across the atmosphere-ocean interface at regional to basin scale. Providing estimates of these latent and sensible heat fluxes over the global ocean necessitates the use of satellite or reanalysis-based estimates of near surface variables. Recent studies have shown that errors in the surface (10 meter)estimates of humidity and temperature are currently the largest sources of uncertainty in the production of turbulent fluxes from satellite observations. Therefore, emphasis has been placed on reducing the systematic errors in the retrieval of these parameters from microwave radiometers. This study discusses recent improvements in the retrieval of air temperature and humidity through improvements in the choice of algorithms (linear vs. nonlinear) and the choice of microwave sensors. Particular focus is placed on improvements using a neural network approach with a single sensor (Special Sensor Microwave/Imager) and the use of combined sensors from the NASA AQUA satellite platform. The latter algorithm utilizes the unique sampling available on AQUA from the Advanced Microwave Scanning Radiometer (AMSR-E) and the Advanced Microwave Sounding Unit (AMSU-A). Current estimates of uncertainty in the near-surface humidity and temperature from single and multi-sensor approaches are discussed and used to estimate errors in the turbulent fluxes.

  6. Ultra-short FBG based distributed sensing using shifted optical Gaussian filters and microwave-network analysis.

    PubMed

    Cheng, Rui; Xia, Li; Sima, Chaotan; Ran, Yanli; Rohollahnejad, Jalal; Zhou, Jiaao; Wen, Yongqiang; Yu, Can

    2016-02-01

    Ultrashort fiber Bragg gratings (US-FBGs) have significant potential as weak grating sensors for distributed sensing, but the exploitation have been limited by their inherent broad spectra that are undesirable for most traditional wavelength measurements. To address this, we have recently introduced a new interrogation concept using shifted optical Gaussian filters (SOGF) which is well suitable for US-FBG measurements. Here, we apply it to demonstrate, for the first time, an US-FBG-based self-referencing distributed optical sensing technique, with the advantages of adjustable sensitivity and range, high-speed and wide-range (potentially >14000 με) intensity-based detection, and resistance to disturbance by nonuniform parameter distribution. The entire system is essentially based on a microwave network, which incorporates the SOGF with a fiber delay-line between the two arms. Differential detections of the cascaded US-FBGs are performed individually in the network time-domain response which can be obtained by analyzing its complex frequency response. Experimental results are presented and discussed using eight cascaded US-FBGs. A comprehensive numerical analysis is also conducted to assess the system performance, which shows that the use of US-FBGs instead of conventional weak FBGs could significantly improve the power budget and capacity of the distributed sensing system while maintaining the crosstalk level and intensity decay rate, providing a promising route for future sensing applications. PMID:26906822

  7. Comparative study of carbon dioxide sensing by Sn-doped TiO2 nanoparticles synthesized by microwave-assisted and solid-state diffusion route

    NASA Astrophysics Data System (ADS)

    Nemade, K. R.; Waghuley, S. A.

    2015-04-01

    Gas sensor based on Sn-doped titanium dioxide (TiO2) nanoparticles has been fabricated and evaluated for carbon dioxide (CO2) sensing. The Sn-doped TiO2 nanoparticles were synthesized by microwave-assisted and solid-state diffusion route. The structure and morphology of resulting samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ultraviolet-visible (UV-VIS) spectroscopy was employed to study the optical properties. The weight loss of samples was analyzed through thermo gravimetric analysis (TGA). The Sn-doped TiO2 nanoparticles synthesized through microwave route exhibited good sensing characteristics.

  8. Microwave radiometer experiment of soil moisture sensing at BARC test site during summer 1981

    NASA Technical Reports Server (NTRS)

    Wang, J.; Jackson, T.; Engman, E. T.; Gould, W.; Fuchs, J.; Glazer, W.; Oneill, P.; Schmugge, T. J.; Mcmurtrey, J., III

    1984-01-01

    Soil moisture was measured by truck mounted microwave radiometers at the frequencies of 1.4 GHz, 5 GHz, and 10.7 GHz. The soil textures in the two test sites were different so that the soil type effect of microwave radiometric response could be studied. Several fields in each test site were prepared with different surface roughnesses and vegetation covers. Ground truth on the soil moisture, temperature, and the biomass of the vegetation was acquired in support of the microwave radiometric measurements. Soil bulk density for each of the fields in both test sites was sampled. The soils in both sites were measured mechanically and chemically. A tabulation of the measured data is presented and the sensors and operational problems associated with the measurements are discussed.

  9. Snow Depth Spatial Distribution Using Microwave Remote Sensing at the Puna Tsang River Basin in Bhutan

    NASA Astrophysics Data System (ADS)

    Duran-Ballen, S.; Tsutsui, H.; Koike, T.

    2012-12-01

    Spatial distribution of snow amount derived from satellite observations has been previously achieved for flat region. But for mountainous regions, spatial distribution of snow amount has not been addressed because remote sensing instruments are very sensitive to the effect of the terrain slope; and because there is no available data for validation. This study focuses on the estimation of snow amount using a microwave radiative transfer model (RTM) in mountain region. AMSR-E satellite observations of brightness temperature (Tb) at 18.7GHz and 36.5GHz frequencies are compared to calculated values of Tb in Lookup Tables generated by the RTM model. The model uses a snow algorithm to derive the snow depth and temperature spatial distribution over the target region. This snow algorithm has been previously validated in a flat region using in-situ recorded snow-depth data. In this study, the local slope in mountainous terrain, where the local incidence angle is different than the 55 degree incidence angle from the satellite, is taken into account. The local incidence angle is calculated from the scalar product between the radiometer scanning vector and the surface normal vector of the local slope. The terrain DEM is used to calculate the slope and aspect of each terrain grid. Then, with the geolocation of the satellite as it passes over, the local incidence angle is computed. AMSR-E data resolution is about 25x25 km but at this resolution we can not meaningfully express the topographic terrain. Therefore, a DEM resolution of 1x1 km is used. To overcome the difference of spatial resolution between the satellite observation and the terrain grid, the approach is to estimate the Tb for the 18.7GHz and 36.5GHz frequencies with the local incidence angle for each terrain grid. Then, an averaged Tb for each footprint is computed from the weighted average of the Tb of each terrain grid based on the count of occurrence of the same local incidence angle. Then, the averaged Tb is

  10. Spaceborne microwave remote sensing of seasonal freeze-thaw processes in theterrestrial high l atitudes : relationships with land-atmosphere CO2 exchange

    NASA Technical Reports Server (NTRS)

    McDonald, Kyle C.; Kimball, John S.; Zhao, Maosheng; Njoku, Eni; Zimmermann, Reiner; Running, Steven W.

    2004-01-01

    Landscape transitions between seasonally frozen and thawed conditions occur each year over roughly 50 million square kilometers of Earth's Northern Hemisphere. These relatively abrupt transitions represent the closest analog to a biospheric and hydrologic on/off switch existing in nature, affecting surface meteorological conditions, ecological trace gas dynamics, energy exchange and hydrologic activity profoundly. We utilize time series satellite-borne microwave remote sensing measurements from the Special Sensor Microwave Imager (SSM/I) to examine spatial and temporal variability in seasonal freeze/thaw cycles for the pan-Arctic basin and Alaska. Regional measurements of spring thaw timing are derived using daily brightness temperature measurements from the 19 GHz, horizontally polarized channel, separately for overpasses with 6 AM and 6 PM equatorial crossing times. Spatial and temporal patterns in regional freeze/thaw dynamics show distinct differences between North America and Eurasia, and boreal forest and Arctic tundra biomes. Annual anomalies in the timing of thawing in spring also correspond closely to seasonal atmospheric CO2 concentration anomalies derived from NOAA CMDL arctic and subarctic monitoring stations. Classification differences between AM and PM overpass data average approximately 5 days for the region, though both appear to be effective surrogates for monitoring annual growing seasons at high latitudes.

  11. Spaceborne Microwave Remote Sensing of Seasonal Freeze-Thaw Processes in the Terrestrial High Latitudes: Relationships with Land-Atmosphere CO2 exchange

    NASA Technical Reports Server (NTRS)

    McDonald, Kyle C.; Kimball, John S.; Zhao, Maosheng; Njoku, Eni; Zimmermann, Reiner; Running, Steven W.

    2004-01-01

    Landscape transitions between seasonally frozen and thawed conditions occur each year over roughly 50 million square kilometers of Earth's Northern Hemisphere. These relatively abrupt transitions represent the closest analog to a biospheric and hydrologic on/off switch existing in nature, affecting surface meteorological conditions, ecological trace gas dynamics, energy exchange and hydrologic activity profoundly. We utilize time series satellite-borne microwave remote sensing measurements from the Special Sensor Microwave Imager (SSM/I) to examine spatial and temporal variability in seasonal freeze/thaw cycles for the pan-Arctic basin and Alaska. Regional measurements of spring thaw timing are derived using daily brightness temperature measurements from the 19 GHz, horizontally polarized channel, separately for overpasses with 6 AM and 6 PM equatorial crossing times. Spatial and temporal patterns in regional freeze/thaw dynamics show distinct differences between North America and Eurasia, and boreal forest and Arctic tundra biomes. Annual anomalies in the timing of thawing in spring also correspond closely to seasonal atmospheric CO2 concentration anomalies derived from NOAA CMDL arctic and subarctic monitoring stations. Classification differences between AM and PM overpass data average approximately 5 days for the region, though both appear to be effective surrogates for monitoring annual growing seasons at high latitudes.

  12. Application of NASA's modern era retrospective-analysis in Global Wetlands Mappings Derived from Coarse-Resolution Satellite Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Schröder, R.; McDonald, K. C.; Podest, E.; Jones, L. A.; Kimball, J. S.; Pinto, N.; Zimmermann, R.; Küppers, M.

    2011-12-01

    The sensitivity of Earth's wetlands to observed shifts in global precipitation and temperature patterns and their ability to produce large quantities of methane gas are key global change questions. Global methane emissions are typically estimated via process-based models calibrated to individual wetland sites. Regardless of the complexity of these process-based models, accurate geographical distribution and seasonality of recent global wetland extent are typically not accounted for in such an approach, which may explain the large variations in estimated global methane emissions as well as the significant interannual variations in the observed atmospheric growth rate of methane. Spatially comprehensive ground observation networks of large-scale inundation patterns are very sparse because they require large fiscal, technological and human resources. Satellite remote sensing of global inundation dynamics thus can support the ability for a complete synoptic view of past and current inundation dynamics over large areas that otherwise could not be assessed. Coarse-resolution (~25km) satellite data from passive and active microwave instruments are well suited for the global observation of large-scale inundation patterns because they are primarily sensitive to the associated dielectric properties of the landscape and cover large areas within a relatively short amount of time (up to daily repeat in high latitudes). This study summarizes a new remote sensing technique for quantifying global daily surface water fractions based on combined passive-active microwave remote sensing data sets from the AMSR-E and QuikSCAT instruments over a 7 year period (July 2002 - July 2009). We apply these data with ancillary land cover maps from MODIS to: 1) define the potential global domain of surface water impacted land; 2) establish land cover driven predictive equations for implementing a dynamic mixture model adjusted to total column water vapor obtained from NASA's modern era

  13. Orbiting multi-beam microwave radiometer for soil moisture remote sensing

    NASA Technical Reports Server (NTRS)

    Shiue, J. C.; Lawrence, R. W.

    1985-01-01

    The effects of soil moisture and other factors on soil surface emissivity are reviewed and design concepts for a multibeam microwave radiometer with a 15 m antenna are described. Characteristic antenna gain and radiation patterns are shown and losses due to reflector roughness are estimated.

  14. The advanced microwave precipitation radiometer: A new aircraft radiometer for passive precipitation remote sensing

    NASA Technical Reports Server (NTRS)

    Hood, Robbie E.; Spencer, Roy W.; James, Mark W.

    1991-01-01

    Past studies of passive microwave measurements of precipitating systems have yielded broad empirical relationships between hydrometeors and microwave transmission. In general, these relationships fall into two categories of passive microwave precipitation retrievals rely upon the observed effect of liquid precipitation to increase the brightness temperature of a radiometrically cold background such as an ocean surface. A scattering-based method is based upon the effect that frozen hydrometeors tend to decrease the brightness temperature of a radiometrically warm background such as land. One step toward developing quantitative brightness temperature-rain rate relationships is the recent construction of a new aircraft instrument sponsored by National Aeronautics and Space Administration/Marshall Space Flight Center (NASA/MSFC). This instrument is the Advanced Microwave Precipitation Radiometer (AMPR) designed and built by Georgia Tech Research Institute to fly aboard high altitude research aircraft such as the NASA ER-2. The AMPR and its accompanying data acquisition system are mounted in the Q-bay compartment of the NASA ER-2.

  15. Microwave Remote Sensing of Ocean Surface Wind Speed and Rain Rates over Tropical Storms

    NASA Technical Reports Server (NTRS)

    Swift, C. T.; Dehority, D. C.; Black, P. G.; Chien, J. Z.

    1984-01-01

    The value of using narrowly spaced frequencies within a microwave band to measure wind speeds and rain rates over tropical storms with radiometers is reviewed. The technique focuses on results obtained in the overflights of Hurricane Allen during 5 and 8 of August, 1980.

  16. Application of near-field microwave sensing techniques for segregation detection in concrete members

    NASA Astrophysics Data System (ADS)

    Bois, K. J.; Benally, A. D.; Zoughi, R.; Nowak, P. S.

    2000-05-01

    In this presentation, a simple, low-cost near-field microwave nondestructive inspection technique for segregation detection in concrete members is presented. This process employs information from the measured magnitude of reflection coefficient at the aperture of an open-ended rectangular waveguide sensor. These measurements, whose results will be presented, were conducted using a Hewlett-Packard HP8510B network analyzer. However, in practice a simple and relatively inexpensive inspection apparatus constructed from discrete microwave components can easily be employed. It is shown that the standard deviation of magnitude of reflection coefficient measurement is linearly correlated with the aggregate density in concrete. Furthermore, for concrete in which the aggregate has segregated, this measurable parameter will change as a function of vertical position of the microwave scan. Results correlating the microwave measurements to the actual aggregate density of a well consolidated concrete specimen and a specimen in which the aggregate has segregated will be presented. Finally, the simple and low cost application of this method for in situ detection of aggregate segregation in concrete structures will be discussed.

  17. Hybrid Architecture Active Wavefront Sensing and Control

    NASA Technical Reports Server (NTRS)

    Feinberg, Lee; Dean, Bruce; Hyde, Tupper

    2010-01-01

    A method was developed for performing relatively high-speed wavefront sensing and control to overcome thermal instabilities in a segmented primary mirror telescope [e.g., James Webb Space Telescope (JWST) at L2], by using the onboard fine guidance sensor (FGS) to minimize expense and complexity. This FGS performs centroiding on a bright star to feed the information to the pointing and control system. The proposed concept is to beam split the image of the guide star (or use a single defocused guide star image) to perform wavefront sensing using phase retrieval techniques. Using the fine guidance sensor star image for guiding and fine phasing eliminates the need for other, more complex ways of achieving very accurate sensing and control that is needed for UV-optical applications. The phase retrieval occurs nearly constantly, so passive thermal stability over fourteen days is not required. Using the FGS as the sensor, one can feed segment update information to actuators on the primary mirror that can update the primary mirror segment fine phasing with this frequency. Because the thermal time constants of the primary mirror are very slow compared to this duration, the mirror will appear extremely stable during observations (to the level of accuracy of the sensing and control). The sensing can use the same phase retrieval techniques as the JWST by employing an additional beam splitter, and having each channel go through a weak lens (one positive and one negative). The channels can use common or separate detectors. Phase retrieval can be performed onboard. The actuation scheme would include a coarse stage able to achieve initial alignment of several millimeters of range (similar to JWST and can use a JWST heritage sensing approach in the science camera) and a fine stage capable of continual updates.

  18. Microwave remote sensing of rain-on-snow events in the subarctic with AMSR2 and GPM observations

    NASA Astrophysics Data System (ADS)

    Brucker, L.; Munchak, S. J.

    2014-12-01

    Climate change in high northern latitudes is predicted to be greater in winter than in summer, and to have increasing, widespread impacts in northern ecosystems. Some of the resulting unknowns are the effects of an increasing frequency of sudden, short-lasting winter warming events, which can lead to rain on snow (ROS). Very little is known about ROS in northern regions, and even less about its cumulative impact on surface energy balance, permafrost, snow melt, and hydrological processes. Since, wintertime warming events have become more frequent in sub-Arctic regions, ROS event characteristics (frequency, extent, and duration) may represent new and relevant climate indicators. However, ROS event detection is challenging.In this presentation, we propose new approaches to monitor the occurrence of ROS events using satellite passive and active microwave sensors. Specifically, we utilize observations from Advanced Microwave Scanning Radiometer 2 (AMSR2), Global Precipitation Measurements (GPM) Microwave Imager (GMI), and GPM Dual-frequency Precipitation Radar (DPR). GPM was launched in February, 2014. It operates multiple radiometers (in the frequency range 10 - 183 GHz), and two radars (Ku and Ka bands). GPM observations are used to quantify rainfall or snowfall rates and are thus appropriate to monitor ROS events up to 66° North.Our satellite monitoring of the ROS event is based on both temporal and spectral variations in the satellite observations. We discuss the observed ROS radiometric signatures using a Multi-Layer microwave emission model based on the Dense Media Radiative Transfer theory (DMRT-ML). In addition, our monitoring is evaluated against atmospheric reanalysis from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim, and NASA Modern-Era Retrospective analysis for Research and Applications (MERRA). This initial evaluation in winter months shows that the proposed ROS detection using microwave sensors occur in areas that are shown

  19. Error characterisation of global active and passive microwave soil moisture datasets

    NASA Astrophysics Data System (ADS)

    Dorigo, W. A.; Scipal, K.; Parinussa, R. M.; Liu, Y. Y.; Wagner, W.; de Jeu, R. A. M.; Naeimi, V.

    2010-12-01

    Understanding the error structures of remotely sensed soil moisture observations is essential for correctly interpreting observed variations and trends in the data or assimilating them in hydrological or numerical weather prediction models. Nevertheless, a spatially coherent assessment of the quality of the various globally available datasets is often hampered by the limited availability over space and time of reliable in-situ measurements. As an alternative, this study explores the triple collocation error estimation technique for assessing the relative quality of several globally available soil moisture products from active (ASCAT) and passive (AMSR-E and SSM/I) microwave sensors. The triple collocation is a powerful statistical tool to estimate the root mean square error while simultaneously solving for systematic differences in the climatologies of a set of three linearly related data sources with independent error structures. Prerequisite for this technique is the availability of a sufficiently large number of timely corresponding observations. In addition to the active and passive satellite-based datasets, we used the ERA-Interim and GLDAS-NOAH reanalysis soil moisture datasets as a third, independent reference. The prime objective is to reveal trends in uncertainty related to different observation principles (passive versus active), the use of different frequencies (C-, X-, and Ku-band) for passive microwave observations, and the choice of the independent reference dataset (ERA-Interim versus GLDAS-NOAH). The results suggest that the triple collocation method provides realistic error estimates. Observed spatial trends agree well with the existing theory and studies on the performance of different observation principles and frequencies with respect to land cover and vegetation density. In addition, if all theoretical prerequisites are fulfilled (e.g. a sufficiently large number of common observations is available and errors of the different datasets are

  20. Microwave and Beam Activation of Nanostructured Catalysts for Environmentally Friendly, Energy Efficient Heavy Crude Oil Processing

    SciTech Connect

    2009-03-01

    This factsheet describes a study whose goal is initial evaluation and development of energy efficient processes which take advantage of the benefits offered by nanostructured catalysts which can be activated by microwave, RF, or radiation beams.

  1. Effects of microwave heating on porous structure of regenerated powdered activated carbon used in xylose.

    PubMed

    Li, Wei; Wang, Xinying; Peng, Jinhui

    2014-01-01

    The regeneration of spent powdered activated carbons used in xylose decolourization by microwave heating was investigated. Effects of microwave power and microwave heating time on the adsorption capacity of regenerated activated carbons were evaluated. The optimum conditions obtained are as follows: microwave power 800W; microwave heating time 30min. Regenerated activated carbon in this work has high adsorption capacities for the amount of methylene blue of 16 cm3/0.1 g and the iodine number of 1000.06mg/g. The specific surface areas of fresh commercial activated carbon, spent carbon and regenerated activated carbon were calculated according to the Brunauer, Emmett and Teller method, and the pore-size distributions of these carbons were characterized by non-local density functional theory (NLDFT). The results show that the specific surface area and the total pore volume of regenerated activated carbon are 1064 m2/g and 1.181 mL/g, respectively, indicating the feasibility of regeneration of spent powdered activated carbon used in xylose decolourization by microwave heating. The results of surface fractal dimensions also confirm the results of isotherms and NLDFT. PMID:24645431

  2. Microwave remote sensing of soil moisture, volume 1. [Guymon, Oklahoma and Dalhart, Texas

    NASA Technical Reports Server (NTRS)

    Mcfarland, M. J. (Principal Investigator); Theis, S. W.; Rosenthal, W. D.; Jones, C. L.

    1982-01-01

    Multifrequency sensor data from NASA's C-130 aircraft were used to determine which of the all weather microwave sensors demonstrated the highest correlation to surface soil moisture over optimal bare soil conditions, and to develop and test techniques which use visible/infrared sensors to compensate for the vegetation effect in this sensor's response to soil moisture. The L-band passive microwave radiometer was found to be the most suitable single sensor system to estimate soil moisture over bare fields. The perpendicular vegetation index (PVI) as determined from the visible/infrared sensors was useful as a measure of the vegetation effect on the L-band radiometer response to soil moisture. A linear equation was developed to estimate percent field capacity as a function of L-band emissivity and the vegetation index. The prediction algorithm improves the estimation of moisture significantly over predictions from L-band emissivity alone.

  3. High altitude airborne remote sensing mission using the advanced microwave precipitation radiometer (AMPR)

    NASA Technical Reports Server (NTRS)

    Galliano, J.; Platt, R. H.; Spencer, Roy; Hood, Robbie

    1991-01-01

    The advanced microwave precipitation radiometer (AMPR) is an airborne multichannel imaging radiometer used to better understand how the earth's climate structure works. Airborne data results from the October 1990 Florida thunderstorm mission in Jacksonville, FL, are described. AMPR data on atmospheric precipitation in mesoscale storms were retrieved at 10.7, 19.35, 37.1, and 85.5 GHz onboard the ER-2 aircraft at an altitude of 20 km. AMPR's three higher-frequency data channels were selected to operate at the same frequencies as the spaceborne special sensor microwave/imager (SSM/I) presently in orbit. AMPR uses two antennas to receive the four frequencies: the lowest frequency channel uses a 9.7-in aperture lens antennas, while the three higher-frequency channels share a separate 5.3-in aperture lens antenna. The radiometer's temperature resolution performance is summarized.

  4. Passive microwave remote sensing of soil moisture from an aircraft platform

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Schmugge, T. J.; Oneill, P.

    1984-01-01

    A series of experiments were conducted over several years using an aircraft platform to study the relationship between passive microwave data and surface soil moisture. Sensor systems included thermal infrared and multifrequency passive microwave instruments. Aircraft measurements were obtained concurrently with ground observations of soil moisture and land cover. Test sites included areas in both humid and semiarid regions of the United States that were typical of these regions. Data analyses indicated that the basic cause and effect relationships between the sensor measurements and soil moisture can be extrapolated from theory and small scale tests to larger resolution elements observed by the aircraft. Pastures in different climatic regions showed similar responses. Vegetation canopy attenuation was verified. Based on these studies the optimal surface soil moisture sensor using passive techniques was a 21-cm wavelength radiometer.

  5. On the use of passive microwaves at 37 GHz in remote sensing of vegetation

    NASA Technical Reports Server (NTRS)

    Kerr, Y. H.; Njoku, E. G.

    1993-01-01

    Recently, a number of studies have investigated the use of the 37 GHz channels of the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) for vegetation monitoring and for studying synergisms between the SMMR and the NOAA Advanced Very High Resolution Radiometer (AVHRR). The approaches are promising but raise a number of issues concerning interpretation of the results, specifically on the relative effects of vegetation and other surface and atmospheric characteristics on the observed signal. This article analyzes the 37 GHz Microwave Polarization Difference Temperature (MPDT) in terms of its sensitivity to surface and atmospheric parameters. For this, a radiative transfer model is used which indicates some limitations of the MPDT index and suggests the importance of accounting for atmospheric effects in the data analysis. An alternative approach to the MPDT, including lower SMMR frequencies than 37 GHz, is discussed.

  6. Microwave sensing technology issues related to a global change technology architecture trade study

    NASA Technical Reports Server (NTRS)

    Campbell, Thomas G.; Shiue, Jim; Connolly, Denis; Woo, Ken

    1991-01-01

    The objectives are to enable the development of lighter and less power consuming, high resolution microwave sensors which will operate at frequencies from 1 to 200 GHz. These systems will use large aperture antenna systems (both reflector and phased arrays) capable of wide scan angle, high polarization purity, and utilize sidelobe suppression techniques as required. Essentially, the success of this technology program will enable high resolution microwave radiometers from geostationary orbit, lightweight and more efficient radar systems from low Earth orbit, and eliminate mechanical scanning methods to the fullest extent possible; a main source of platform instability in large space systems. The Global Change Technology Initiative (GCTI) will develop technology which will enable the use of satellite systems for Earth observations on a global scale.

  7. Use of a cloud-sensing radar and a microwave radiometer as a stratus cloud profiler

    SciTech Connect

    Frisch, A.S.; Fairall, C.W.; Snider, J.B.

    1994-12-31

    Remote sensors such as radar offer an alternate approach to the study of could and drizzle properties. Combining stratus cloud measurements from a K{sub {alpha}}-band radar and microwave radiometer can give profiles of liquid water and droplet distribution. In addition, in drizzle, the radar measurements can be used to estimate drizzle parameters such as number concentration, liquid water, and droplet distribution.

  8. Wave theory for microwave remote sensing of a half-space random medium with three-dimensional variations

    NASA Technical Reports Server (NTRS)

    Tsang, L.; Kong, J. A.

    1979-01-01

    The two-variable expansion technique is used to solve for the mean Green's functions from the Dyson equation under the nonlinear approximation for a half-space random medium with three-dimensional correlation functions. The Bethe-Salpeter equations are then solved under the ladder approximation. The radiative transfer equations, which have been applied extensively in the study of microwave remote sensing problems, are derived under these approximations. The limiting cases of large and small horizontal correlation lengths are discussed. It is found that there is only one propagation constant except for the case of large horizontal correlation lengths, in which there are two propagation constants. It is shown that boundary layer appears in first-order solutions and does not appear in zeroth-order solutions.

  9. Microwave assisted combustion synthesis of nanocrystalline CoFe{sub 2}O{sub 4} for LPG sensing

    SciTech Connect

    Chaudhari, Prashant; Acharya, S. A. Darunkar, S. S.; Gaikwad, V. M.

    2015-08-28

    A microwave-assisted citrate precursor method has been utilized for synthesis of nanocrystalline powders of CoFe{sub 2}O{sub 4}. The process takes only a few minutes to obtain as-synthesized CoFe{sub 2}O{sub 4}. Structural properties of the synthesized material were investigated by X-ray diffraction; scanning electron microscopy, Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy. The gas sensing properties of thick film of CoFe{sub 2}O{sub 4} prepared by screen printing towards Liquid Petroleum Gas (LPG) revealed that CoFe{sub 2}O{sub 4} thick films are sensitive and shows maximum sensitivity at 350°C for 2500 ppm of LPG.

  10. The development of a stepped frequency microwave radiometer and its application to remote sensing of the Earth

    NASA Technical Reports Server (NTRS)

    Harrington, R. F.

    1980-01-01

    The design, development, application, and capabilities of a variable frequency microwave radiometer are described. This radiometer demonstrated the versatility, accuracy, and stability required to provide contributions to the geophysical understanding of ocean and ice processes. A closed-loop feedback method was used, whereby noise pulses were added to the received electromagnetic radiation to achieve a null balance in a Dicke switched radiometer. Stability was achieved through the use of a constant temperature enclosure around the low loss microwave front end. The Dicke reference temperature was maintained to an absolute accuracy of 0.1 K using a closed-loop proportional temperature controller. A microprocessor based digital controller operates the radiometer and records the data on computer compatible tapes. This radiometer exhibits an absolute accuracy of better than 0.5 K when the sensitivity is 0.1 K. The sensitivity varies between 0.0125 K and 1.25 K depending upon the bandwidth and integration time selected by the digital controller. Remote sensing experiments were conducted from an aircraft platform and the first radiometeric mapping of an ocean polar front; exploratory experiments to measure the thickness of lake ice; first discrimination between first year and multiyear ice below 10 GHz; and the first known measurements of frequency sensitive characteristics of sea ice.

  11. Active Sensing System with In Situ Adjustable Sensor Morphology

    PubMed Central

    Nurzaman, Surya G.; Culha, Utku; Brodbeck, Luzius; Wang, Liyu; Iida, Fumiya

    2013-01-01

    Background Despite the widespread use of sensors in engineering systems like robots and automation systems, the common paradigm is to have fixed sensor morphology tailored to fulfill a specific application. On the other hand, robotic systems are expected to operate in ever more uncertain environments. In order to cope with the challenge, it is worthy of note that biological systems show the importance of suitable sensor morphology and active sensing capability to handle different kinds of sensing tasks with particular requirements. Methodology This paper presents a robotics active sensing system which is able to adjust its sensor morphology in situ in order to sense different physical quantities with desirable sensing characteristics. The approach taken is to use thermoplastic adhesive material, i.e. Hot Melt Adhesive (HMA). It will be shown that the thermoplastic and thermoadhesive nature of HMA enables the system to repeatedly fabricate, attach and detach mechanical structures with a variety of shape and size to the robot end effector for sensing purposes. Via active sensing capability, the robotic system utilizes the structure to physically probe an unknown target object with suitable motion and transduce the arising physical stimuli into information usable by a camera as its only built-in sensor. Conclusions/Significance The efficacy of the proposed system is verified based on two results. Firstly, it is confirmed that suitable sensor morphology and active sensing capability enables the system to sense different physical quantities, i.e. softness and temperature, with desirable sensing characteristics. Secondly, given tasks of discriminating two visually indistinguishable objects with respect to softness and temperature, it is confirmed that the proposed robotic system is able to autonomously accomplish them. The way the results motivate new research directions which focus on in situ adjustment of sensor morphology will also be discussed. PMID:24416094

  12. Error characterisation of global active and passive microwave soil moisture data sets

    NASA Astrophysics Data System (ADS)

    Dorigo, W. A.; Scipal, K.; Parinussa, R. M.; Liu, Y. Y.; Wagner, W.; de Jeu, R. A. M.; Naeimi, V.

    2010-08-01

    Understanding the error structures of remotely sensed soil moisture products is essential for correctly interpreting observed variations and trends in the data or assimilating them in hydrological or numerical weather prediction models. Nevertheless, a spatially coherent assessment of the quality of the various globally available data sets is often hampered by the limited availability over space and time of reliable in-situ measurements. This study explores the triple collocation error estimation technique for assessing the relative quality of several globally available soil moisture products from active (ASCAT) and passive (AMSR-E and SSM/I) microwave sensors. The triple collocation technique is a powerful tool to estimate the root mean square error while simultaneously solving for systematic differences in the climatologies of a set of three independent data sources. In addition to the scatterometer and radiometer data sets, we used the ERA-Interim and GLDAS-NOAH reanalysis soil moisture data sets as a third, independent reference. The prime objective is to reveal trends in uncertainty related to different observation principles (passive versus active), the use of different frequencies (C-, X-, and Ku-band) for passive microwave observations, and the choice of the independent reference data set (ERA-Interim versus GLDAS-NOAH). The results suggest that the triple collocation method provides realistic error estimates. Observed spatial trends agree well with the existing theory and studies on the performance of different observation principles and frequencies with respect to land cover and vegetation density. In addition, if all theoretical prerequisites are fulfilled (e.g. a sufficiently large number of common observations is available and errors of the different data sets are uncorrelated) the errors estimated for the remote sensing products are hardly influenced by the choice of the third independent data set. The results obtained in this study can help us in

  13. Investigating Baseline, Alternative and Copula-based Algorithm for combining Airborne Active and Passive Microwave Observations in the SMAP Context

    NASA Astrophysics Data System (ADS)

    Montzka, C.; Lorenz, C.; Jagdhuber, T.; Laux, P.; Hajnsek, I.; Kunstmann, H.; Entekhabi, D.; Vereecken, H.

    2015-12-01

    The objective of the NASA Soil Moisture Active & Passive (SMAP) mission is to provide global measurements of soil moisture and freeze/thaw states. SMAP integrates L-band radar and radiometer instruments as a single observation system combining the respective strengths of active and passive remote sensing for enhanced soil moisture mapping. Airborne instruments will be a key part of the SMAP validation program. Here, we present an airborne campaign in the Rur catchment, Germany, in which the passive L-band system Polarimetric L-band Multi-beam Radiometer (PLMR2) and the active L-band system F-SAR of DLR were flown simultaneously on the same platform on six dates in 2013. The flights covered the full heterogeneity of the area under investigation, i.e. all types of land cover and experimental monitoring sites with in situ sensors. Here, we used the obtained data sets as a test-bed for the analysis of three active-passive fusion techniques: A) The SMAP baseline algorithm: Disaggregation of passive microwave brightness temperature by active microwave backscatter and subsequent inversion to soil moisture, B), the SMAP alternative algorithm: Estimation of soil moisture by passive sensor data and subsequent disaggregation by active sensor backscatter and C) Copula-based combination of active and passive microwave data. For method C empirical Copulas were generated and theoretical Copulas fitted both on the level of the raw products brightness temperature and backscatter as well as two soil moisture products. Results indicate that the regression parameters for method A and B are dependent on the radar vegetation index (RVI). Similarly, for method C the best performance was gained by generating separate Copulas for individual land use classes. For more in-depth analyses longer time series are necessary as can obtained by airborne campaigns, therefore, the methods will be applied to SMAP data.

  14. Microwave heating enhances antioxidant and emulsifying activities of ovalbumin glycated with glucose in solid-state.

    PubMed

    Tu, Zong-Cai; Hu, Yue-Ming; Wang, Hui; Huang, Xiao-Qin; Xia, Shi-Qi; Niu, Pei-Pei

    2015-03-01

    The aim of this study was to characterize the properties of ovalbumin (OVA) after glycated with glucose under microwave heating. For this purpose, microwave at 480 and 640 W power levels were used for heating the OVA-glucose system in solid-state for 0, 5, 10, 15, 20 and 25 min, respectively. The results indicated that the protein molecular weight was increased after glycated with glucose under microwave treatment, the pH of the system was decreased with the increase of microwave treatment power and time, while the UV absorbance, browning intensity, antioxidant activities as well as the emulsifying activity and emulsion stability of the Maillard reaction products (MRPs) were increased in according with the raise of microwave treatment power and time. The reaction time of microwave treatment is much shorter than those using traditional methods, suggesting that microwave irradiation is a novel and efficient approach to promote Maillard reaction (MR) in dry state and improve protein antioxidant and functional properties. PMID:25745213

  15. Volcanic eruption source parameters from active and passive microwave sensors

    NASA Astrophysics Data System (ADS)

    Montopoli, Mario; Marzano, Frank S.; Cimini, Domenico; Mereu, Luigi

    2016-04-01

    It is well known, in the volcanology community, that precise information of the source parameters characterising an eruption are of predominant interest for the initialization of the Volcanic Transport and Dispersion Models (VTDM). Source parameters of main interest would be the top altitude of the volcanic plume, the flux of the mass ejected at the emission source, which is strictly related to the cloud top altitude, the distribution of volcanic mass concentration along the vertical column as well as the duration of the eruption and the erupted volume. Usually, the combination of a-posteriori field and numerical studies allow constraining the eruption source parameters for a given volcanic event thus making possible the forecast of ash dispersion and deposition from future volcanic eruptions. So far, remote sensors working at visible and infrared channels (cameras and radiometers) have been mainly used to detect, track and provide estimates of the concentration content and the prevailing size of the particles propagating within the ash clouds up to several thousand of kilometres far from the source as well as track back, a-posteriori, the accuracy of the VATDM outputs thus testing the initial choice made for the source parameters. Acoustic wave (infrasound) and microwave fixed scan radar (voldorad) were also used to infer source parameters. In this work we want to put our attention on the role of sensors operating at microwave wavelengths as complementary tools for the real time estimations of source parameters. Microwaves can benefit of the operability during night and day and a relatively negligible sensitivity to the presence of clouds (non precipitating weather clouds) at the cost of a limited coverage and larger spatial resolution when compared with infrared sensors. Thanks to the aforementioned advantages, the products from microwaves sensors are expected to be sensible mostly to the whole path traversed along the tephra cloud making microwaves particularly

  16. Theoretical study of thermally activated magnetization switching under microwave assistance: Switching paths and barrier height

    NASA Astrophysics Data System (ADS)

    Suto, H.; Kudo, K.; Nagasawa, T.; Kanao, T.; Mizushima, K.; Sato, R.; Okamoto, S.; Kikuchi, N.; Kitakami, O.

    2015-03-01

    Energy barrier height for magnetization switching is theoretically studied for a system with uniaxial anisotropy in a circularly polarized microwave magnetic field. A formulation of the Landau-Lifshitz-Gilbert equation in a rotating frame introduces an effective energy that includes the effects of both the microwave field and static field. This allows the effective-energy profiles to rigorously describe the switching paths and corresponding barrier height, which govern thermally activated magnetization switching under microwave assistance. We show that fixed points and limit cycles in the rotating frame lead to various switching paths and that under certain conditions, switching becomes a two-step process with an intermediate state.

  17. Active/passive microwave sensor comparison of MIZ-ice concentration estimates. [Marginal Ice Zone (MIZ)

    NASA Technical Reports Server (NTRS)

    Burns, B. A.; Cavalieri, D. J.; Keller, M. R.

    1986-01-01

    Active and passive microwave data collected during the 1984 summer Marginal Ice Zone Experiment in the Fram Strait (MIZEX 84) are used to compare ice concentration estimates derived from synthetic aperture radar (SAR) data to those obtained from passive microwave imagery at several frequencies. The comparison is carried out to evaluate SAR performance against the more established passive microwave technique, and to investigate discrepancies in terms of how ice surface conditions, imaging geometry, and choice of algorithm parameters affect each sensor. Active and passive estimates of ice concentration agree on average to within 12%. Estimates from the multichannel passive microwave data show best agreement with the SAR estimates because the multichannel algorithm effectively accounts for the range in ice floe brightness temperatures observed in the MIZ.

  18. Galactic Noise and Passive Microwave Remote Sensing from Space At L-Band

    NASA Technical Reports Server (NTRS)

    LeVine, David M.; Abraham, Saji; Hildebrand Peter H. (Technical Monitor)

    2002-01-01

    The spectral window at L-band (1.4 GHz) is important for passive remote sensing of soil moisture and ocean salinity from space, parameters that are needed to understand the hydrologic cycle and ocean circulation. At this frequency, radiation from extraterrestrial (mostly galactic) sources is strong and, unlike the constant cosmic background, this radiation is spatially variable. This paper presents a modern radiometric map of the celestial sky at L-band and a solution for the problem of determining what portion of the sky is seen by a radiometer in orbit. The data for the radiometric map is derived from recent radio astronomy surveys and is presented as equivalent brightness temperature suitable for remote sensing applications. Examples using orbits and antennas representative of those contemplated for remote sensing of soil moisture and sea surface salinity from space are presented to illustrate the signal levels to be expected. Near the galactic plane, the contribution can exceed several Kelvin.

  19. Passive microwave sensing of soil moisture content: Soil bulk density and surface roughness

    NASA Technical Reports Server (NTRS)

    Wang, J. R.

    1982-01-01

    Microwave radiometric measurements over bare fields of different surface roughnesses were made at the frequencies of 1.4 GHz, 5 GHz, and 10.7 GHz to study the frequency dependence as well as the possible time variation of surface roughness. The presence of surface roughness was found to increase the brightness temperature of soils and reduce the slope of regression between brightness temperature and soil moisture content. The frequency dependence of the surface roughness effect was relatively weak when compared with that of the vegetation effect. Radiometric time series observation over a given field indicated that field surface roughness might gradually diminish with time, especially after a rainfall or irrigation. This time variation of surface roughness served to enhance the uncertainty in remote soil moisture estimate by microwave radiometry. Three years of radiometric measurements over a test site revealed a possible inconsistency in the soil bulk density determination, which turned out to be an important factor in the interpretation of radiometric data.

  20. Atmospheric effect on microwave polarimetric passive remote sensing of ocean surfaces

    NASA Astrophysics Data System (ADS)

    Yeang, Chen-Pang; Yueh, Simon H.; Ding, Kung-Hau; Kong, Jin Au

    1999-03-01

    A theoretical emission model of combined ocean surface and atmosphere is presented to predict the microwave emissivity of the ocean. The modeled ocean surface is one-dimensional with a random rough profile. The electromagnetic scattering from the surface is calculated based on the extended boundary condition method. Realizations of rough surfaces are created using Monte Carlo simulations. The bistatic scattering coefficients are computed from the ensemble average. The millimeter-wave propagation model is used to evaluate the absorption of microwave radiation at all height levels in the atmosphere. An expression for the observed brightness temperatures is derived by solving the radiative transfer equations. The radiative transfer model results show a good agreement with the measured data from the 1995 NASA Jet Propulsion Laboratory WIND radiometer (WINDRAD) campaign. An approximate model is provided to estimate the atmospheric effect on the ocean brightness temperatures based on the overall atmospheric attenuation. The approximate model also compares well with the WINDRAD data. Further comparisons are made between the approximate formula and the radiative transfer results on the ratio of the third Stokes parameter in the atmosphere to the one in free space by varying the atmospheric conditions, surface roughness, and radiation frequencies. The approximate formula shows its usefulness for the prediction of the ocean brightness temperatures.

  1. Characterization of Aroma-Active Compounds in Microwave Blanced Peanuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microwave blanching of peanuts has been explored as an alternative to conventional oven methods based on its speed of operation, energy savings, and efficiency of process control. Although processing times can be greatly reduced,the occurrence of stale/floral and ashy off-flavors has been reported a...

  2. A multifrequency evaluation of active and passive microwave sensors for oil spill detection and assessment

    NASA Technical Reports Server (NTRS)

    Fenner, R. G.; Reid, S. C.; Solie, C. H.

    1980-01-01

    An evaluation is given of how active and passive microwave sensors can best be used in oil spill detection and assessment. Radar backscatter curves taken over oil spills are presented and their effect on synthetic aperture radar (SAR) imagery are discussed. Plots of microwave radiometric brightness variations over oil spills are presented and discussed. Recommendations as to how to select the best combination of frequency, viewing angle, and sensor type for evaluation of various aspects of oil spills are also discussed.

  3. Update on active chem-bio sensing

    NASA Astrophysics Data System (ADS)

    Swim, Cynthia; Vanderbeek, Richard; Emge, Darren; Wong, Anna

    2005-05-01

    The US Army Edgewood Chemical Biological Center (ECBC) is the leader in development of military systems for chemical and biological defense, in collaboration with all Services, other Government laboratories, academia, and industry. Chemical and biological optical sensing principles, unique capabilities, state-of-the-art sensors, and emerging technologies will be discussed. In order to acquire highly quantified data, study the effects of variables such as particle size distribution on backscatter coefficients, perform iterative aerosol algorithm development, and characterize breadboards, a novel "windowless" Vortex Chamber utilizing air curtains was developed and built at ECBC. The chamber has been successfully shown to contain a cloud of known size, concentration, and particle size distribution for 10-15 minutes. Near-term plans are focused on characterization of breadboards for standoff bio discrimination and deducing absolute backscatter coefficients from Vortex Chamber data.

  4. Remote sensing application to regional activities

    NASA Technical Reports Server (NTRS)

    Shahrokhi, F.; Jones, N. L.; Sharber, L. A.

    1976-01-01

    Two agencies within the State of Tennessee were identified whereby the transfer of aerospace technology, namely remote sensing, could be applied to their stated problem areas. Their stated problem areas are wetland and land classification and strip mining studies. In both studies, LANDSAT data was analyzed with the UTSI video-input analog/digital automatic analysis and classification facility. In the West Tennessee area three land-use classifications could be distinguished; cropland, wetland, and forest. In the East Tennessee study area, measurements were submitted to statistical tests which verified the significant differences due to natural terrain, stripped areas, various stages of reclamation, water, etc. Classifications for both studies were output in the form of maps of symbols and varying shades of gray.

  5. Low-cost electronic microwave calibration for rapid on-line moisture sensing of seedcotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to improve rapid on-line moisture sensing of seedcotton in cotton gins, a means by which to establish a reliable wide-band electronic calibration is critically needed. This calibration is needed to center the circuit due to changes in the internal signal delays and attenuations caused by te...

  6. A physical algorithm to measure sea ice concentration from passive microwave remote sensing data

    NASA Astrophysics Data System (ADS)

    Tikhonov, V. V.; Repina, I. A.; Raev, M. D.; Sharkov, E. A.; Ivanov, V. V.; Boyarskii, D. A.; Alexeeva, T. A.; Komarova, N. Yu.

    2015-10-01

    A conceptually new algorithm of sea ice concentration retrieval in polar regions from satellite microwave radiometry data is discussed. The algorithm design favorably contrasts with that of known modern algorithms. Its design is based on a physical emission model of the "sea surface - sea ice - snow cover - atmosphere" system. No tie-points are used in the algorithm. All the calculation expressions are derived from theoretical modeling. The design of the algorithm minimizes the impact of atmospheric variability on sea ice concentration retrieval. Beside estimating sea ice concentration, the algorithm makes it possible to indicate ice areas with melting snow and melt ponds. The algorithm is simple to use, no complicated or time consuming calculations are involved.

  7. Passive microwave remote sensing of soil moisture - The effect of tilled row structure

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Newton, R. W.; Rouse, J. W., Jr.

    1980-01-01

    The tilled row structure in agricultural fields is one of the important factors affecting observations of microwave emission from such fields. Measurements of this effect were performed with L-band and X-band radiometers mounted on a mobile truck on a bare 40 m x 45 m row tilled field; the soil moisture content during measurements ranged from 10 to 30% by dry weight. Results showed that the variations of the antenna temperatures with incident angle changed with the azimuth angle measured from the row direction. It is found that the observed difference between horizontally and vertically polarized antenna temperatures is due to the change in the local angle of field emission within the antenna field of view caused by the large-scale row structure.

  8. Ground-based microwave remote sensing of water vapor in the mesosphere and stratosphere

    NASA Technical Reports Server (NTRS)

    Croskey, Charles L.; Olivero, John J.; Martone, Joseph P.

    1991-01-01

    A ground-based, portable microwave radiometer that will be used to measure water vapor in the 30-80-km altitude region, and is to operate 24 hr a day, is described. The thermally excited 22.235-GHz rotational-transition line of water vapor is employed. The emission from this region produces a signal with an apparent brightness temperature of the order 0.1 to 0.5 K. A steerable reflector is used to provide optimal viewing angles, depending on the geographic location and season. Periodic tipping curve scans by this reflector permit determination of the amount of tropospheric correction that is applied to the data. All local oscillators in the receiver are crystal-controlled so that narrow-band spectral analysis of the received line shape can be performed.

  9. The Passive Microwave Remote Sensing of Soil Moisture: the Effect of Tilled Row Structure

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Newton, R. W.; Rouse, J. W.

    1979-01-01

    The tilled rowstructure is known to be one of the important factors affecting the observations of the microwave emission from a natural surface. Measurements of this effect were carried out with both I and X band radiometers mounted on a mobile truck on a bare 40 m x 45 m row tilled field. The soil moisture content during the measurements ranged from approximately 10 percent to approximately 30 percent by dry weight. The results of these measurements showed that the variations of the antenna temperatures with incident angle theta changed with the azimuthal angle a measured from the row direction. A numerical calculation based on a composite surface roughness was made and found to predict the observed features within the model's limit of accuracy. It was concluded that the difference between the horizontally and vertically polarized temperatures was due to the change in the local angle of field emission within the antenna field of view caused by the large scale row structure.

  10. Using Multi-Dimensional Microwave Remote Sensing Information for the Retrieval of Soil Surface Roughness

    NASA Astrophysics Data System (ADS)

    Marzahn, P.; Ludwig, R.

    2016-06-01

    In this Paper the potential of multi parametric polarimetric SAR (PolSAR) data for soil surface roughness estimation is investigated and its potential for hydrological modeling is evaluated. The study utilizes microwave backscatter collected from the Demmin testsite in the North-East Germany during AgriSAR 2006 campaign using fully polarimetric L-Band airborne SAR data. For ground truthing extensive soil surface roughness in addition to various other soil physical properties measurements were carried out using photogrammetric image matching techniques. The correlation between ground truth roughness indices and three well established polarimetric roughness estimators showed only good results for Re[ρRRLL] and the RMS Height s. Results in form of multitemporal roughness maps showed only satisfying results due to the fact that the presence and development of particular plants affected the derivation. However roughness derivation for bare soil surfaces showed promising results.

  11. Passive Microwave Remote Sensing of Rainfall Considering the Effects of Wind and Nonprecipitating Clouds

    NASA Technical Reports Server (NTRS)

    Qihang Li.; Bras, Rafael L.; Veneziano, Daniele

    1996-01-01

    It has long been shown both in theory and in observation that emission from rain drops in a raining cloud results in upwelling brightness temperature above that caused by the sea surface alone. High brightness temperatures at microwave frequencies (e.g. 37 and 19 GHz) have usually been quantitatively associated with rainfall using physical or statistical models. By comparing concurrent special sensor microwave/imager and radar data, however, we noticed many cases where there is no appreciable rainfall in a field of view (FOV) which exhibits high brightness temperature (T(sub B)) at 37 and 19 GHz. On the basis of calculations and past literature it is shown that such high brightness temperatures can be caused by nonprecipitating clouds and by wind. The effect of the wind is to create wave and high-emissivity foam on the sea surface. A model is developed to relate T(sub B) to the fractional coverage of rain, f, within a FOV. The parameters of the model are calibrated by fitting the model to the observed brightness temperature and fractional rain coverage data. The critical parameter of the model, T(sub B min.), which is the threshold brightness temperature for the presence of rain, depends on the strength of the storm. The strength of the storm is characterized by the fraction of the FOVs within a large area that have T(sub B) higher than 240 K, which is readily obtainable from satellite data alone. The instantaneous FOV rain rate R can then be obtained through the f approximately R relationship which is empirically derived using radar data. An algorithm has been proposed based on the T(sub B) approximately f and f approximately R relationship. Application of the algorithm to TOGA-COARE and Darwin storms results in reasonable instantaneous FOV rain estimate. When averaged over the entire radar scan, a more accurate and unbiased areal rain estimate can be achieved.

  12. Synergism of active and passive microwave data for estimating bare surface soil moisture

    NASA Technical Reports Server (NTRS)

    Saatchi, Sasan S.; Njoku, Eni G.; Wegmueller, Urs

    1993-01-01

    Active and passive microwave sensors were applied effectively to the problem of estimating the surface soil moisture in a variety of environmental conditions. Research to date has shown that both types of sensors are also sensitive to the surface roughness and the vegetation cover. In estimating the soil moisture, the effect of the vegetation and roughness are often corrected either by acquiring multi-configuration (frequency and polarization) data or by adjusting the surface parameters in order to match the model predictions to the measured data. Due to the limitations on multi-configuration spaceborne data and the lack of a priori knowledge of the surface characteristics for parameter adjustments, it was suggested that the synergistic use of the sensors may improve the estimation of the soil moisture over the extreme range of naturally occurring soil and vegetation conditions. To investigate this problem, the backscattering and emission from a bare soil surface using the classical rough surface scattering theory were modeled. The model combines the small perturbation and the Kirchhoff approximations in conjunction with the Peak formulation to cover a wide range of surface roughness parameters with respect to frequency for both active and passive measurements. In this approach, the same analytical method was used to calculate the backscattering and emissivity. Therefore, the active and passive simulations can be combined at various polarizations and frequencies in order to estimate the soil moisture more actively. As a result, it is shown that (1) the emissivity is less dependent on the surface correlation length, (2) the ratio of the backscattering coefficient (HH) over the surface reflectivity (H) is almost independent of the soil moisture for a wide range of surface roughness, and (3) this ratio can be approximated as a linear function of the surface rms height. The results were compared with the data obtained by a multi-frequency radiometer

  13. Scanning near field microwave microscopy based on an active resonator

    NASA Astrophysics Data System (ADS)

    Qureshi, Naser; Kolokoltsev, Oleg; Ordonez-Romero, Cesar Leonardo

    2014-03-01

    A large number of recent implementations of near field scanning microwave microscopy (NFSMM) have been based on the perturbation of a resonant cavity connected to a sharp scanning probe. In this work we present results from an alternative approach: the perturbation of a microwave source connected to a scanning tip. Based on a yittrium iron garnet (YIG) cavity ring resonator this scanning probe system has a quality factor greater than 106, which allows us to detect very small frequency shifts, which translates to a very high sensitivity in sample impedance measurements. Using a selection of representative semiconductor, metal and biological samples we show how this approach leads to unusually high sensitivity and spatial resolution. Work supported by a grant from PAPIIT, UNAM 104513.

  14. Making Sense of Multiple Physical Activity Recommendations.

    ERIC Educational Resources Information Center

    Corbin, Charles B.; LeMasurier, Guy; Franks, B. Don

    2002-01-01

    This digest provides basic information designed to help people determine which of the many physical activity guidelines are most appropriate for use in specific situations. After an introduction, the digest focuses on: "Factors to Consider in Selecting Appropriate Physical Activity Guidelines" (group credibility and purpose, benefits to be…

  15. Microwave-assisted activation for electroless nickel plating on PMMA microspheres

    NASA Astrophysics Data System (ADS)

    Chen, Yen-Chung; Liu, Robert Lian-Huey; Chen, Xin-Liang; Shu, Hsiou-Jeng; Ger, Ming-Der

    2011-05-01

    A novel microwave-assisted activation method for electroless plating on PMMA microspheres is presented in this study. When the microwave irradiation was applied during the activation step, the amount of the Pd species adsorbed on PMMA surfaces was much higher than that of sample pretreated with a conventional activation process without microwave irradiation. With this activation method, it was also shown that the adsorbed Pd species with a size of 4-6 nm were uniformly distributed on the surfaces of the PMMA microspheres, thus a smooth and uniform nickel-phosphorus coating on the PMMA microspheres was obtained by subsequent electroless plating. The samples after each step were characterized by XPS, TEM, ICP and SEM.

  16. Dual-tunable multiferroic active ring filter for microwave photonic oscillators

    NASA Astrophysics Data System (ADS)

    Vitko, V. V.; Nikitin, A. A.; Ustinov, A. B.; Kalinikos, B. A.

    2015-12-01

    A theoretical model of a microwave active ring filter based on a ferrite-ferroelectric layered structure serving as a waveguide for spin-electromagnetic waves is developed. An experimental prototype of the device is fabricated and characterized. The device is implemented as an active-ring resonator with a microwave amplifier and a ferrite-ferroelectric delay line. The resonance properties of this system are studied theoretically and experimentally. The results show dual control of central frequency of the filter with magnetic and electric fields. An effective Q-factor of 50 000 and tuning by 5 MHz with an electric field are achieved at 8 GHz.

  17. Development of a one-dimensional electro-thermophysical model of the snow sea-ice system: Arctic climate processes and microwave remote sensing applications

    NASA Astrophysics Data System (ADS)

    Hanesiak, John Michael

    Snow covered sea ice plays a crucial role in the earth's climate. This includes polar biology, local, regional and world weather and ocean circulations as well as indigenous people's way of life. Recent research has indicated significant climate change in the polar regions, especially the Canadian arctic. Polar climate processes are also among the most poorly misrepresented within global circulation models (GCMs). The goal of this thesis is to improve our understanding and capability to simulate arctic climate processes in a predictive sense. An electro-thermophysical relationship exists between the thermophysical characteristics (climate variables and processes) and electrical properties (dielectrics) that control microwave remote sensing of snow-covered first- year sea ice (FYI). This work explicitly links microwave dielectrics and a thermodynamic model of snow and sea ice by addressing four key issues. These includes: (1)ensure the existing one-dimensional sea ice models treat the surface energy balance (SEB) and snow/ice thermodynamics in the appropriate time scales we see occurring in field experiments, (2)ensure the snow/ice thermodynamics are not compromised by differences in environmental and spatial representation within components of the SEB, (3)ensure the snow layer is properly handled in the modeling environment, and (4)how we can make use of satellite microwave remote sensing data within the model environment. Results suggest that diurnal processes are critical and need to be accounted for in modeling snow-covered FYI, similar to time scales acting in microwave remote sensing signatures. Output from the coupled snow sea-ice model provides the required input to microwave dielectric models of snow and sea ice to predict microwave penetration depths within the snow and sea ice (an Electro-Thermophysical model of the Snow Sea Ice System (ETSSIS)). Results suggest ETSSIS can accurately simulate microwave penetration depths in the cold dry snow season and

  18. Cost-sensitive Bayesian control policy in human active sensing

    PubMed Central

    Ahmad, Sheeraz; Huang, He; Yu, Angela J.

    2014-01-01

    An important but poorly understood aspect of sensory processing is the role of active sensing, the use of self-motion such as eye or head movements to focus sensing resources on the most rewarding or informative aspects of the sensory environment. Here, we present behavioral data from a visual search experiment, as well as a Bayesian model of within-trial dynamics of sensory processing and eye movements. Within this Bayes-optimal inference and control framework, which we call C-DAC (Context-Dependent Active Controller), various types of behavioral costs, such as temporal delay, response error, and sensor repositioning cost, are explicitly minimized. This contrasts with previously proposed algorithms that optimize abstract statistical objectives such as anticipated information gain (Infomax) (Butko and Movellan, 2010) and expected posterior maximum (greedy MAP) (Najemnik and Geisler, 2005). We find that C-DAC captures human visual search dynamics better than previous models, in particular a certain form of “confirmation bias” apparent in the way human subjects utilize prior knowledge about the spatial distribution of the search target to improve search speed and accuracy. We also examine several computationally efficient approximations to C-DAC that may present biologically more plausible accounts of the neural computations underlying active sensing, as well as practical tools for solving active sensing problems in engineering applications. To summarize, this paper makes the following key contributions: human visual search behavioral data, a context-sensitive Bayesian active sensing model, a comparative study between different models of human active sensing, and a family of efficient approximations to the optimal model. PMID:25520640

  19. Cost-sensitive Bayesian control policy in human active sensing.

    PubMed

    Ahmad, Sheeraz; Huang, He; Yu, Angela J

    2014-01-01

    An important but poorly understood aspect of sensory processing is the role of active sensing, the use of self-motion such as eye or head movements to focus sensing resources on the most rewarding or informative aspects of the sensory environment. Here, we present behavioral data from a visual search experiment, as well as a Bayesian model of within-trial dynamics of sensory processing and eye movements. Within this Bayes-optimal inference and control framework, which we call C-DAC (Context-Dependent Active Controller), various types of behavioral costs, such as temporal delay, response error, and sensor repositioning cost, are explicitly minimized. This contrasts with previously proposed algorithms that optimize abstract statistical objectives such as anticipated information gain (Infomax) (Butko and Movellan, 2010) and expected posterior maximum (greedy MAP) (Najemnik and Geisler, 2005). We find that C-DAC captures human visual search dynamics better than previous models, in particular a certain form of "confirmation bias" apparent in the way human subjects utilize prior knowledge about the spatial distribution of the search target to improve search speed and accuracy. We also examine several computationally efficient approximations to C-DAC that may present biologically more plausible accounts of the neural computations underlying active sensing, as well as practical tools for solving active sensing problems in engineering applications. To summarize, this paper makes the following key contributions: human visual search behavioral data, a context-sensitive Bayesian active sensing model, a comparative study between different models of human active sensing, and a family of efficient approximations to the optimal model. PMID:25520640

  20. Future Radiometer Systems for Earth Remote Sensing

    NASA Technical Reports Server (NTRS)

    Wilson, William J.; Njoku, Eni G.

    2000-01-01

    This paper will describe a new exciting concept for using microwave systems for Earth remote sensing. This concept will use a 6-m diameter mesh deployable antenna with active and passive systems to provide moderate spatial resolution images at L and S-band microwave frequencies.

  1. Ambient vibration monitoring of slender structures by microwave interferometer remote sensing

    NASA Astrophysics Data System (ADS)

    Gikas, Vassilis

    2012-11-01

    This paper examines the potential of microwave radar interferometry for monitoring the dynamic behaviour of large civil engineering works. It provides an overview of the method, its principles of operation with particular emphasis given on the IBIS-S system. Two areas of application are considered and the results of the analyses are presented and discussed. The first experimental study involves the monitoring of the dynamic response of a tall power plant chimney due to wind load. The second example examines the dynamic behaviour of a long cable-stayed bridge. In this case, the focus is placed on the effects that individual traffic events impose on the vibration response of the main span of the bridge deck and the bridge pylons. Analysis of the results provides detailed displacement time-histories and the dominant frequencies observed at the top of the chimney and along the bridge deck and the top of the towers. Also, cross-comparisons and discussions with the results obtained at the same structures using different sensor configurations are provided.

  2. Passive and Active Sensing Technologies for Structural Health Monitoring

    NASA Astrophysics Data System (ADS)

    Do, Richard

    A combination of passive and active sensing technologies is proposed as a structural health monitoring solution for several applications. Passive sensing is differentiated from active sensing in that with the former, no energy is intentionally imparted into the structure under test; sensors are deployed in a pure detection mode for collecting data mined for structural health monitoring purposes. In this thesis, passive sensing using embedded fiber Bragg grating optical strain gages was used to detect varying degrees of impact damage using two different classes of features drawn from traditional spectral analysis and auto-regressive time series modeling. The two feature classes were compared in detail through receiver operating curve performance analysis. The passive detection problem was then augmented with an active sensing system using ultrasonic guided waves (UGWs). This thesis considered two main challenges associated with UGW SHM including in-situ wave propagation property determination and thermal corruption of data. Regarding determination of wave propagation properties, of which dispersion characteristics are the most important, a new dispersion curve extraction method called sparse wavenumber analysis (SWA) was experimentally validated. Also, because UGWs are extremely sensitive to ambient temperature changes on the structure, it significantly affects the wave propagation properties by causing large errors in the residual error in the processing of the UGWs from an array. This thesis presented a novel method that compensates for uniform temperature change by considering the magnitude and phase of the signal separately and applying a scalable transformation.

  3. Determination of land surface temperature and soil moisture from Tropical Rainfall Measuring Mission/Microwave Imager remote sensing data

    NASA Astrophysics Data System (ADS)

    Wen, Jun; Su, Zhongbo; Ma, Yaoming

    2003-01-01

    An analytical algorithm for the determination of land surface temperature and soil moisture from the Tropical Rainfall Measuring Mission/Microwave Imager (TRMM/TMI) remote sensing data has been developed in this study. The error analyses indicate that the uncertainties of the enrolled parameters will not cause serious errors in the proposed algorithm. By applying the proposed algorithm to TRMM/TMI remote sensing data collected during the Global Energy and Water Experiment (GEWEX) Asian Monsoon Experiment (GAME)/Tibet Intensive Observation Period field campaign in 1998 (IOP'98), the temporal and regional distributions of land surface temperature and volumetric soil moisture are evaluated over the central Tibetan plateau area. To validate the proposed method, the ground-measured surface temperature and volumetric soil moisture are compared to TRMM/TMI-derived land surface temperature and soil Fresnel reflectivity respectively. The results show that the estimated surface temperature is in good agreement with ground measurements; their difference and correlation coefficient are 0.52 ± 2.41 K and 0.80, respectively. A quasi-linear relationship exists between estimated Fresnel reflectivity and ground-measured volumetric soil moisture with a correlation coefficient 0.82. The land surface thermal status can also be clearly identified from the regional distribution of the estimated land surface temperature; the mountainous area and water bodies have a very lower surface temperature, while the river basin shows a higher surface temperature compared to the mountainous area. The southeastern part of the selected area has lower soil moisture, while the river basin exhibits high soil moisture. It is therefore concluded that the proposed algorithm is successful for the retrieval of land surface temperature and soil moisture using TRMM/TMI data over the study area.

  4. Modeling multi-layer effects in passive microwave remote sensing of dry snow using Dense Media Radiative Transfer Theory (DMRT) based on quasicrystalline approximation

    USGS Publications Warehouse

    Liang, D.; Xu, X.; Tsang, L.; Andreadis, K.M.; Josberger, E.G.

    2008-01-01

    The Dense Media Radiative Transfer theory (DMRT) of Quasicrystalline Approximation of Mie scattering by sticky particles is used to study the multiple scattering effects in layered snow in microwave remote sensing. Results are illustrated for various snow profile characteristics. Polarization differences and frequency dependences of multilayer snow model are significantly different from that of the single-layer snow model. Comparisons are also made with CLPX data using snow parameters as given by the VIC model. ?? 2007 IEEE.

  5. Combined effect of microwave and activated carbon on the remediation of polychlorinated biphenyl-contaminated soil.

    PubMed

    Liu, Xitao; Yu, Gang

    2006-04-01

    The application of microwave and activated carbon for the treatment of polychlorinated biphenyl (PCB) contaminated soil was explored in this study with a model compound of 2,4,5-trichlorobiphenyl (PCB29). PCB-contaminated soil was treated in a quartz reactor by microwave irradiation at 2450MHz with the addition of granular activated carbon (GAC). In this procedure, GAC acted as microwave absorbent for reaching high temperature and reductant for dechlorination. A sheltered type-K thermocouple was applied to record the temperature rising courses. It was shown that the addition of GAC could effectively promote the temperature rising courses. The determination of PCB residues in soil by gas chromatography (GC) revealed that rates of PCB removal were highly dependent on microwave power, soil moisture content, and the amount of GAC added. GC with mass spectrum (MS) detector and ion chromatography were employed for the analysis of degradation intermediates and chlorine ions, respectively. It was suggested that microwave irradiation with the assistance of activated carbon might be a potential technology for the remediation of PCB-contaminated soil. PMID:16213557

  6. Active vibrissal sensing in rodents and marsupials

    PubMed Central

    Mitchinson, Ben; Grant, Robyn A.; Arkley, Kendra; Rankov, Vladan; Perkon, Igor; Prescott, Tony J.

    2011-01-01

    In rats, the long facial whiskers (mystacial macrovibrissae) are repetitively and rapidly swept back and forth during exploration in a behaviour known as ‘whisking’. In this paper, we summarize previous evidence from rats, and present new data for rat, mouse and the marsupial grey short-tailed opossum (Monodelphis domestica) showing that whisking in all three species is actively controlled both with respect to movement of the animal's body and relative to environmental structure. Using automatic whisker tracking, and Fourier analysis, we first show that the whisking motion of the mystacial vibrissae, in the horizontal plane, can be approximated as a blend of two sinusoids at the fundamental frequency (mean 8.5, 11.3 and 7.3 Hz in rat, mouse and opossum, respectively) and its second harmonic. The oscillation at the second harmonic is particularly strong in mouse (around 22 Hz) consistent with previous reports of fast whisking in that species. In all three species, we found evidence of asymmetric whisking during head turning and following unilateral object contacts consistent with active control of whisker movement. We propose that the presence of active vibrissal touch in both rodents and marsupials suggests that this behavioural capacity emerged at an early stage in the evolution of therian mammals. PMID:21969685

  7. Microwave-assisted synthesis of SnO2 nanorods for oxygen gas sensing at room temperature

    PubMed Central

    Azam, Ameer; Habib, Sami S; Salah, Numan A; Ahmed, Faheem

    2013-01-01

    High-quality single-crystalline SnO2 nanorods were synthesized using a microwave-assisted solution method. The nanorods were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), ultraviolet-visible and Raman spectroscopy, Brunauer–Emmett–Teller (BET), and electrical resistance measurements. The XRD pattern indicated the formation of single-phase SnO2 nanorods with rutile structure. FE-SEM and TEM images revealed tetragonal nanorods of about 450–500 nm in length and 60–80 nm in diameter. The nanorods showed a higher BET surface area of 288 m2/g, much higher than that of previously reported work. The Raman scattering spectra indicated a typical rutile phase of the SnO2. The absorption spectrum showed an absorption peak centered at 340 nm, and the band-gap value was found to be 3.64 eV. The gas-sensing properties of the SnO2 nanorods for oxygen gas with different concentrations were measured at room temperature. It was found that the value of resistance increased with the increase in oxygen gas concentration in the test chamber. The SnO2 nanorods exhibited high sensitivity and rapid response-recovery characteristics to oxygen gas, and could detect oxygen concentration as low as 1, 3, 5, and 10 ppm. PMID:24143091

  8. Optical and ammonia-sensing properties of SnO2 nanoparticles synthesized using a 900 W microwave

    NASA Astrophysics Data System (ADS)

    Klinbumrung, Arrak; Thongtem, Titipun; Phuruangrat, Anukorn; Thongtem, Somchai

    2016-08-01

    SnO2 nanoparticles were successfully synthesized using a 900 W microwave for 10, 20, and 30 min. Tetragonal SnO2 nanoparticles composed of Sn and O were detected by X-ray diffraction (XRD), selected area electron diffraction (SEAD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, and transmission electron microscopy (TEM). The SnO2 nanoparticles processed for 30 min were the best crystals. The 3.5 eV energy gap and 395 nm emission wavelength were determined by UV–visible absorption and photoluminescence (PL) spectroscopy. The gas-sensing performance of SnO2 nanoparticles during exposure to an NH3–air mixture was studied at different working temperatures and NH3 concentrations. At 1055 ppm NH3 and 350 °C, the SnO2 nanoparticles showed a sensitivity of 9.2 with the response and recovery times of 9 and 37 s, respectively.

  9. Fast Numerical Algorithms for 3-D Scattering from PEC and Dielectric Random Rough Surfaces in Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Lisha

    We present fast and robust numerical algorithms for 3-D scattering from perfectly electrical conducting (PEC) and dielectric random rough surfaces in microwave remote sensing. The Coifman wavelets or Coiflets are employed to implement Galerkin's procedure in the method of moments (MoM). Due to the high-precision one-point quadrature, the Coiflets yield fast evaluations of the most off-diagonal entries, reducing the matrix fill effort from O(N2) to O( N). The orthogonality and Riesz basis of the Coiflets generate well conditioned impedance matrix, with rapid convergence for the conjugate gradient solver. The resulting impedance matrix is further sparsified by the matrix-formed standard fast wavelet transform (SFWT). By properly selecting multiresolution levels of the total transformation matrix, the solution precision can be enhanced while matrix sparsity and memory consumption have not been noticeably sacrificed. The unified fast scattering algorithm for dielectric random rough surfaces can asymptotically reduce to the PEC case when the loss tangent grows extremely large. Numerical results demonstrate that the reduced PEC model does not suffer from ill-posed problems. Compared with previous publications and laboratory measurements, good agreement is observed.

  10. Retrieval of data from ground-based microwave sensing of the middle atmosphere: Comparison of two inversion techniques

    SciTech Connect

    Jarchow, C.; Hartogh, P.

    1995-12-31

    Since the discovery of the ozone hole over Antarctica the interest in measuring atmospheric trace gas distributions has greatly increased. First of all scientists are interested in monitoring the long term behavior of the ozone layer over the Antarctic and also over the Arctic region, but in addition one is also interested in measuring and monitoring not so well known trace gases which are assumed to play a central role in ozone depletion. In microwave remote sensing of atmospheric trace gases a retrieval technique has been widely adopted during the last years. The authors found some difficulties in applying this method to the analysis of long term ground-based observations due to the large variability of the tropospheric transmission. The corresponding changes of the data quality and the weight of the apriori profile in the inversion algorithm can lead to an artificial correlation between the retrieved profiles and the transmission. In addition an assessment of the inversion only from the error bars of the profile is impossible since they don`t respond linearly to the errors of the spectra. It is shown that an inversion algorithm according to Backus-Gilbert`s philosophy will avoid these difficulties.

  11. Development of a rainfall model to study rainfall over South Africa using satellite microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Mishra, Anoop Kumar; Rawat, Kishan Singh

    2015-01-01

    In this study, a rainfall model is developed to study rainfall over South Africa (10° to 40°E, 35° to 20°S) using a set of rainfall signatures derived from Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) observations at 0.25 deg×0.25 deg spatial grid. Based on measurements at 19-, 21-, and 85-GHz channels of TMI, the scattering index (SI) is derived. Polarization corrected temperature (PCT) is calculated using measurements at the 85-GHz channel. SI, PCT, and their combinations are tested as rain signatures over South Africa. These rain signatures (i.e., PCT and SI and their combinations) are collocated against precipitation radar (PR) onboard TRMM to derive a relationship between rain rate and rain signatures. Rainfall retrieval is attempted using linear as well as nonlinear regressions. The results have been validated using an independent dataset of PR. It is reported that a nonlinear regression outperforms a linear algorithm. Statistical validation with an independent dataset of PR exhibits the correlation coefficients (CCs) of 0.60, 0.64, and 0.66, and root mean square errors (RMSEs) of 5.82, 6.42, and 5.76 mm/h from observations of SI, PCT, and a combination of SI and PCT, respectively, using linear regressions. When nonlinear regression is used, the CC of 0.69, 0.68, and 0.70 and RMSE of 4.75, 4.89, and 4.38 mm/h are observed from the SI, PCT, and the combination of SI and PCT, respectively.

  12. Model-estimated microwave emissions from rain systems for remote sensing applications

    NASA Astrophysics Data System (ADS)

    Smirnov, Mikhail T.; Meischner, Peter F.

    1996-12-01

    A simple model for estimating the upward and downward microwave emission from rain layer types above ground is presented. The emission properties of the rain layers are estimated from physical quantities such as the optical depth, the single-scattering albedo, the physical temperature, and a given drop size distribution for Mie scattering calculations. The underlying surface is characterized by the emissivity and the physical temperature. The transparency coefficient q and the reflection coefficient r of the rain layer are expressed by these physical quantities. The brightness temperature then is given by the physical temperature T, q, and r. The radiation transfer is estimated by the method of layer addition, described by Sobolev [1956], which avoids the necessity of solving the equation of radiation transfer. The accuracy of this simple model was estimated by comparisons with three-dimensional Monte Carlo calculations. The error is estimated to be less than 3 K for common situations and less than 8 K for unrealistic high optical depths. It is shown that any one of the quantities rain rate, rain layer depth, and physical temperature can be estimated with sufficient accuracy if the others are known. The basic model has been extended for application to inhomogeneous cloud layers and to include differences in brightness temperatures for horizontal and vertical polarizations for oblate raindrops. The main intended application of this model is rain rate estimation from space with low data processing efforts, especially for the Priroda mission. The model was tested for the downwelling emission during the field experiment CLEOPATRA by measurements with a polarimetric weather radar and rain gauges. The results verify the principles, and promising agreement was found at least for stratiform rain. The polarimetric extension of the model too showed promising results under quite different measurement conditions in Russia and southern Germany.

  13. Passive microwave remote sensing of rainfall with SSM/I: Algorithm development and implementation

    NASA Technical Reports Server (NTRS)

    Ferriday, James G.; Avery, Susan K.

    1994-01-01

    A physically based algorithm sensitive to emission and scattering is used to estimate rainfall using the Special Sensor Microwave/Imager (SSM/I). The algorithm is derived from radiative transfer calculations through an atmospheric cloud model specifying vertical distributions of ice and liquid hydrometeors as a function of rain rate. The algorithm is structured in two parts: SSM/I brightness temperatures are screened to detect rainfall and are then used in rain-rate calculation. The screening process distinguishes between nonraining background conditions and emission and scattering associated with hydrometeors. Thermometric temperature and polarization thresholds determined from the radiative transfer calculations are used to detect rain, whereas the rain-rate calculation is based on a linear function fit to a linear combination of channels. Separate calculations for ocean and land account for different background conditions. The rain-rate calculation is constructed to respond to both emission and scattering, reduce extraneous atmospheric and surface effects, and to correct for beam filling. The resulting SSM/I rain-rate estimates are compared to three precipitation radars as well as to a dynamically simulated rainfall event. Global estimates from the SSM/I algorithm are also compared to continental and shipboard measurements over a 4-month period. The algorithm is found to accurately describe both localized instantaneous rainfall events and global monthly patterns over both land and ovean. Over land the 4-month mean difference between SSM/I and the Global Precipitation Climatology Center continental rain gauge database is less than 10%. Over the ocean, the mean difference between SSM/I and the Legates and Willmott global shipboard rain gauge climatology is less than 20%.

  14. Microwave open-ended coaxial dielectric probe: interpretation of the sensing volume re-visited

    PubMed Central

    2014-01-01

    Background Tissue dielectric properties are specific to physiological changes and consequently have been pursued as imaging biomarkers of cancer and other pathological disorders. However, a recent study (Phys Med Biol 52:2637–2656, 2007; Phys Med Biol 52:6093–6115, 2007), which utilized open-ended dielectric probing techniques and a previously established sensing volume, reported that the dielectric property contrast may only be 10% or less between breast cancer and normal fibroglandular tissue whereas earlier data suggested ratios of 4:1 and higher may exist. Questions about the sensing volume of this probe relative to the amount of tissue interrogated raise the distinct possibility that the conclusions drawn from that study may have been over interpreted. Methods We performed open-ended dielectric probe measurements in two-layer compositions consisting of a background liquid and a planar piece of Teflon that was translated to predetermined distances away from the probe tip to assess the degree to which the probe produced property estimates representative of the compositional averages of the dielectric properties of the two materials resident within a small sensing volume around the tip of the probe. Results When Teflon was in contact with the probe, the measured properties were essentially those of pure Teflon whereas the properties were nearly identical to those of the intervening liquid when the Teflon was located more than 2 mm from the probe tip. However, when the Teflon was moved closer to the probe tip, the dielectric property measurements were not linearly related to the compositional fraction of the two materials, but reflected nearly 50% of those of the intervening liquid at separation distances as small as 0.2 mm, and approximately 90% of the liquid when the Teflon was located 0.5 mm from the probe tip. Conclusion These results suggest that the measurement methods reported in the most recent breast tissue dielectric property study are not likely

  15. Browsing Image Collections with Representations of Common-Sense Activities.

    ERIC Educational Resources Information Center

    Gordon, Andrew S.

    2001-01-01

    Describes a methodology for creating networks of subject terms by manually representing a large number of common-sense activities that are broadly related to image subject terms. Application of this methodology to the Library of Congress Thesaurus for Graphic Materials produced 768 representations that supported users of a prototype browsing-based…

  16. Estimating Land Surface Fluxes Using Microwave and Thermal Remote Sensing Data During SMEX02/SMACEX

    NASA Astrophysics Data System (ADS)

    Li, F.; Kustas, W. P.; Jackson, T. J.; Bindlish, R.; Prueger, J. H.

    2005-05-01

    A two-source (soil + vegetation) energy balance model using microwave-derived near-surface soil moisture (TSMSM) as input was applied to a corn and soybean production region in central Iowa. Six days of the Polarimetric Scanning Radiometer (PSR) derived soil moisture data and Landsat derived vegetation information as well as local meteorological data were used to run the model. These data were acquired during the Soil Moisture Experiment in 2002 (SMEX02) and the Soil Moisture Atmosphere Coupling Experiment (SMACEX). The PSR derived soil moisture maps at 800 m resolution which were resampled to 30 m. At this higher resolution, a flux footprint model was applied to weight pixels within the source area of the flux tower measurements. The root mean square difference (RMSD) values between TSMSM estimated and tower measured net radiation, Rn, and soil heat flux, G, were within 25 Wm-2. The TSMSM model also produced reasonable estimates of sensible heat (H) and latent heat flux (LE) with both RMSD values for H and LE being within 55 Wm-2. The TSMSM model output was also compared with estimates from the two-source model version using radiometric surface temperature observations (TSMTH) from Landsat. The results from two Landsat overpasses under partial canopy cover on July 1, 2002, and near full cover on July 8 indicate that TSMSM gave similar results (slightly better) to TSMTH for July 1, but did not perform as well for July 8. When the two models were in good agreement, the surface temperature estimated from TSMSM agreed closely with the Landsat radiometric temperature observations. By contrast, when TSMSM output gave greater differences with TSMTH flux estimates and tower measurements such as July 8, the TSMSM model generally computed lower LE and higher H than TSMTH and the tower measurements. This resulted in TSMSM producing significantly higher surface temperatures than Landsat radiometric temperature observations. Both soil moisture and fractional vegetation cover

  17. Active Wave Propagation and Sensing in Plates

    NASA Technical Reports Server (NTRS)

    Ghoshal, Anindya; Martin, William N.; Sundaresan, Mannur J.; Schulz, Mark J.; Ferguson, Frederick

    2001-01-01

    Health monitoring of aerospace structures can be done using an active interrogation approach with diagnostic Lamb waves. Piezoelectric patches are often used to generate the waves, and it is helpful to understand how these waves propagate through a structure. To give a basic understanding of the actual physical process of wave propagation, a model is developed to simulate asymmetric wave propagation in a panel and to produce a movie of the wave motion. The waves can be generated using piezoceramic patches of any size or shape. The propagation, reflection, and interference of the waves are represented in the model. Measuring the wave propagation is the second important aspect of damage detection. Continuous sensors are useful for measuring waves because of the distributed nature of the sensor and the wave. Two sensor designs are modeled, and their effectiveness in measuring acoustic waves is studied. The simulation model developed is useful to understand wave propagation and to optimize the type of sensors that might be used for health monitoring of plate-like structures.

  18. Investigation of the effects of summer melt on the calculation of sea ice concentration using active and passive microwave data

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J.; Burns, Barbara A.; Onstott, Robert G.

    1990-01-01

    The effects of ice surface melt on microwave signatures and errors in the calculation of sea ice concentration are examined, using active and passive microwave data sets from the Marginal Ice Zone Experiment aircraft flights in the Fram Strait region. Consideration is given to the possibility of using SAR to supplement passive microwave data to unambiguously discriminate between open water areas and ponded floes. Coincident active multichannel microwave radiometer and SAR measurements of individual floes are used to describe the effects of surface melt on sea ice concentration calculations.

  19. In vitro anti-quorum sensing activity of phytol.

    PubMed

    Pejin, Boris; Ciric, Ana; Glamoclija, Jasmina; Nikolic, Milos; Sokovic, Marina

    2015-01-01

    Anti-quorum sensing activity of the diterpene phytol was evaluated in vitro for the first time. This compound (at three sub-MIC concentrations - 0.5, 0.25 and 0.125 MIC, respectively) reduced the formation of Pseudomonas aeruginosa PAO1 biofilm in the range of 74.00-84.33% exhibiting higher activity than the both positive controls used, streptomycin and ampicillin. Phytol (0.5 MIC) also effectively reduced P. aeruginosa twitching and flagella motility. Indeed, the bacteria treated were incapable of producing a twitching zone and had almost round, smooth and regular colony edges. Finally, the tested compound (0.5 MIC) exhibited good P. aeruginosa pyocyanin inhibitory activity (51.94%) practically to the same extent as streptomycin (52.09%). According to the experimental data obtained, this phytol property may inspire design of medical foods targeting P. aeruginosa quorum sensing activity. PMID:25103916

  20. Interferometric synthetic aperture microwave radiometry for the remote sensing of the earth

    NASA Technical Reports Server (NTRS)

    Ruf, Christopher S.; Swift, Calvin T.; Tanner, Alan B.; Le Vine, David M.

    1988-01-01

    Interferometric aperture synthesis is presented as an alternative to real aperture measurements of the earth's brightness temperature from low earth orbit. The signal-to-noise performance of a single interferometric measurement is considered, and the noise characteristics of the brightness temperature image produced from the interferometer measurements are discussed. The sampling requirements of the measurements and the resulting effects of the noise in the measurements on the image are described. The specific case of the electronically steered thinned array radiometer (ESTAR) currently under construction is examined. The ESTAR prototype is described in detail sufficient to permit a performance evaluation of its spatial and temperature resolution. Critical aspects of an extension of the ESTAR sensor to a larger spaceborne system are considered. Of particular importance are the number and placement of antenna elements in the imaging array. A comparison of the implementation methodologies of radio astronomy and earth remote sensing is presented along with the effects of the source brightness distribution, the antenna array configuration and the method used for array scanning.

  1. Optically powered active sensing system for Internet Of Things

    NASA Astrophysics Data System (ADS)

    Gao, Chen; Wang, Jin; Yin, Long; Yang, Jing; Jiang, Jian; Wan, Hongdan

    2014-10-01

    Internet Of Things (IOT) drives a significant increase in the extent and type of sensing technology and equipment. Sensors, instrumentation, control electronics, data logging and transmission units comprising such sensing systems will all require to be powered. Conventionally, electrical powering is supplied by batteries or/and electric power cables. The power supply by batteries usually has a limited lifetime, while the electric power cables are susceptible to electromagnetic interference. In fact, the electromagnetic interference is the key issue limiting the power supply in the strong electromagnetic radiation area and other extreme environments. The novel alternative method of power supply is power over fiber (PoF) technique. As fibers are used as power supply lines instead, the delivery of the power is inherently immune to electromagnetic radiation, and avoids cumbersome shielding of power lines. Such a safer power supply mode would be a promising candidate for applications in IOT. In this work, we built up optically powered active sensing system, supplying uninterrupted power for the remote active sensors and communication modules. Also, we proposed a novel maximum power point tracking technique for photovoltaic power convertors. In our system, the actual output efficiency greater than 40% within 1W laser power. After 1km fiber transmission and opto-electric power conversion, a stable electric power of 210mW was obtained, which is sufficient for operating an active sensing system.

  2. Comparison of sea surface winds derived from active and passive microwaves instruments on the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    De Biasio, Francesco; Zecchetto, Stefano

    2013-04-01

    In order to characterize the energy and momentum fluxes at the air-sea interface, the surface wind vector must be known with adequate spatial and temporal coverages. Satellite-borne active and passive microwaves instruments perform such measurements. In the Mediterranean Sea, and in general in enclosed or semi-enclosed basins, an adequate coverage is yet more difficult to achieve than in open sea, because of the presence of vast coastal areas and elevated orography near the coastline. This study aims to compare the performance of three of such instruments (two actives and one passive) over several years of activity over the Mediterranean Sea, in order to delve into the possibility of using the three data-sets as a common reference for marine meteorology investigations, dramatically improving the availability of surface wind data in the Mediterranean Sea. They are the METOP-A ASCAT scatterometer, the QuikSCAT SeaWinds scatterometer and the Coriolis WindSat radiometer. ASCAT and QuikSCAT data are freely available for download, at spatial resolution of 25 km by 25 km and 12.5 km by 12.5 km, from the Physical Oceanography Distributed Active Archive Center PO.DAAC (http://podaac.jpl.nasa.gov). ASCAT near real time data have 2 hours latency. The time span covered by these data is March 2007-present for ASCAT, July 1999-November 2009 for QuikSCAT. In the Mediterranean Sea the nominal temporal coverage is less then 2 hit per point per day for both. WindSat data have spatial resolution of 25 km by 25 km, cover the period February 2003-present, and are freely available for download from Remote Sensing Systems (http://www.ssmi.com). They are available as delayed datasets covering one day at a time. The two collocated datasets cover the period February 2003 - November 2009 (WindSat - QuikSCAT) and March 2009 - November 2010 (WindSat - ASCAT), and offer the means to perform: - a comparison of the performances of active and passive microwaves instruments; - a very long

  3. Soil Moisture Active and Passive Microwave Products: Intercomparison and Evaluation over a Sahelian Site

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper presents a comparison and an evaluation of five soil moisture products based on satellite-based passive and active microwave measurements. Products are evaluated for 2005-2006 against ground measurements obtained from the soil moisture network deployed in Mali (Sahel) in the framework of ...

  4. Microwave-Assisted Copper-Catalyzed Oxidative Cyclization of Acrylamides with Non-Activated Ketones.

    PubMed

    Zhao, Yaping; Sharma, Nandini; Sharma, Upendra K; Li, Zhenghua; Song, Gonghua; Van der Eycken, Erik V

    2016-04-18

    An operationally simple and efficient microwave-assisted protocol for the oxidative cyclization of acrylamide derivatives with non-activated ketones to generate 3,3-disubstituted oxindoles is described. The reaction proceeds by a copper-catalyzed tandem radical addition/cyclization strategy and tolerates a series of functional groups with moderate to excellent yields. PMID:26868308

  5. Assimilation of active and passive microwave observations for improved estimates of soil moisture and crop growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An Ensemble Kalman Filter-based data assimilation framework that links a crop growth model with active and passive (AP) microwave models was developed to improve estimates of soil moisture (SM) and vegetation biomass over a growing season of soybean. Complementarities in AP observations were incorpo...

  6. Inhibitory effect of microwaved thinned nectarine extracts on polyphenol oxidase activity.

    PubMed

    Redondo, Diego; Venturini, María E; Oria, Rosa; Arias, Esther

    2016-04-15

    By-products from agricultural practices or from the fruit processing industry are a source of bioactive compounds that could be used in the food industry. Such by-products include thinned fruits, which are expected to contain high quantities of interesting compounds. One possible application of this fruits is the prevention of the enzymatic browning suffered by fruits and vegetables after minimal processing. The aim of this study is to determine the in vitro and in vivo activity of microwaved extracts obtained from thinned nectarines. It has been observed that in vitro the extracts obtained after the application of high microwave power levels (500, 1000 and 1500 W) are mixed type inhibitors of polyphenoloxidase enzyme, showing an irreversible inactivation. This inhibition could be attributed to the Maillard reaction products formed during the microwave treatment. In vivo, a solution of 2% of the extract obtained at 1500 W inhibited the enzymatic browning in minimally processed peaches for 8 days of storage. PMID:26616994

  7. Depolarization effects in the active remote sensing of random media

    NASA Technical Reports Server (NTRS)

    Zuniga, M.; Kong, J. A.; Tsang, L.

    1980-01-01

    Backscattering cross sections for depolarization are derived for the active remote sensing of a two-layer random medium. It is shown that the depolarization effects arise as a second-order term in albedo under the Born approximation. The results of the backscattering cross sections are illustrated as functions of frequency and incident angles and used to match experimental data collected from a vegetation field.

  8. Synergistic activation of quorum sensing in Vibrio harveyi.

    PubMed

    Mandabi, Aviad; Ganin, Hadas; Meijler, Michael M

    2015-09-15

    Autoinducer-2 (AI-2) has been suggested to serve as a ubiquitous quorum sensing (QS) signal that mediates intra- and interspecies cross-talk between bacteria. To add tools for the study of its function in bacterial communication, we present a new and an improved synthetic route to AI-2 and aromatic analogues. We used this strategy to prepare naphthyl-DPD, and observed remarkably high synergistic activity at low nanomolar concentrations for this analogue in Vibrio harveyi. PMID:26248803

  9. Characteristics of self-sensing actuation for active control

    SciTech Connect

    Barney, P.; Redmond, J.; Smith, D.

    1996-12-31

    The benefits of a collocated sensor actuator pair are well known within the controls community. Generally speaking, collocation offers the use of simple control algorithms with reduced instabilities due to spillover. One method for achieving collocation is the implementation of a ``sentuator`` in which a piezoelectric element functions simultaneously as both a sensor and an actuator. Past work in utilizing a sentuator has primarily been limited to piezoelectric films and patches mounted to flexible structures. Additional papers have provided information and methodology for dealing with the non-linear aspects of a piezoceramic sentuator. The need arises for methods of self-sensing when performing active vibration control of very stiff structures. A method for understanding and using self-sensing lead zirconate titanate stacks for active vibration control is presented. This paper specifically provides a basic understanding of self-sensing methods as applied to stiff structures for the purposes of control. The discussion of the methodology is followed by a simple example in which active vibration control is applied to a model of a boring bar with embedded PZT stacks.

  10. Latest developments in active remote sensing at INO

    NASA Astrophysics Data System (ADS)

    Babin, F.; Forest, R.; Bourliaguet, B.; Cantin, D.; Cottin, P.; Pancrati, O.; Turbide, S.; Lambert-Girard, S.; Cayer, F.; Lemieux, D.; Cormier, J.-F.; Châteauneuf, F.

    2012-09-01

    Remote sensing or stand-off detection using controlled light sources is a well known and often used technique for atmospheric and surface spatial mapping. Today, ground based, vehicle-borne and airborne systems are able to cover large areas with high accuracy and good reliability. This kind of detection based on LiDAR (Light Detection and Ranging) or active Differential Optical Absorption Spectroscopy (DOAS) technologies, measures optical responses from controlled illumination of targets. Properties that can be recorded include volume back-scattering, surface reflectivity, molecular absorption, induced fluorescence and Raman scattering. The various elastic and inelastic backscattering responses allow the identification or characterization of content of the target volumes or surfaces. INO has developed instrumentations to measure distance to solid targets and monitor particles suspended in the air or in water in real time. Our full waveform LiDAR system is designed for use in numerous applications in environmental or process monitoring such as dust detection systems, aerosol (pesticide) drift monitoring, liquid level sensing or underwater bathymetric LiDARs. Our gated imaging developments are used as aids in visibility enhancement or in remote sensing spectroscopy. Furthermore, when coupled with a spectrograph having a large number of channels, the technique becomes active multispectral/hyperspectral detection or imaging allowing measurement of ultra-violet laser induced fluorescence (UV LIF), time resolved fluorescence (in the ns to ms range) as well as gated Raman spectroscopy. These latter techniques make possible the stand-off detection of bio-aerosols, drugs, explosives as well as the identification of mineral content for geological survey. This paper reviews the latest technology developments in active remote sensing at INO and presents on-going projects conducted to address future applications in environmental monitoring.

  11. Measuring thermal budgets of active volcanoes by satellite remote sensing

    NASA Technical Reports Server (NTRS)

    Glaze, L.; Francis, P. W.; Rothery, D. A.

    1989-01-01

    Thematic Mapper measurements of the total radiant energy flux Q at Lascar volcano in north Chile for December 1984 are reported. The results are consistent with the earlier suggestion that a lava lake is the source of a reported thermal budget anomaly, and with values for 1985-1986 that are much lower, suggesting that fumarolic activity was then a more likely heat source. The results show that satellite remote sensing may be used to monitor the activity of a volcano quantitatively, in a way not possible by conventional ground studies, and may provide a method for predicting eruptions.

  12. Estimating Sea Surface Salinity and Wind Using Combined Passive and Active L-Band Microwave Observations

    NASA Technical Reports Server (NTRS)

    Yueh, Simon H.; Chaubell, Mario J.

    2012-01-01

    Several L-band microwave radiometer and radar missions have been, or will be, operating in space for land and ocean observations. These include the NASA Aquarius mission and the Soil Moisture Active Passive (SMAP) mission, both of which use combined passive/ active L-band instruments. Aquarius s passive/active L-band microwave sensor has been designed to map the salinity field at the surface of the ocean from space. SMAP s primary objectives are for soil moisture and freeze/thaw detection, but it will operate continuously over the ocean, and hence will have significant potential for ocean surface research. In this innovation, an algorithm has been developed to retrieve simultaneously ocean surface salinity and wind from combined passive/active L-band microwave observations of sea surfaces. The algorithm takes advantage of the differing response of brightness temperatures and radar backscatter to salinity, wind speed, and direction, thus minimizing the least squares error (LSE) measure, which signifies the difference between measurements and model functions of brightness temperatures and radar backscatter. The algorithm uses the conjugate gradient method to search for the local minima of the LSE. Three LSE measures with different measurement combinations have been tested. The first LSE measure uses passive microwave data only with retrieval errors reaching 1 to 2 psu (practical salinity units) for salinity, and 1 to 2 m/s for wind speed. The second LSE measure uses both passive and active microwave data for vertical and horizontal polarizations. The addition of active microwave data significantly improves the retrieval accuracy by about a factor of five. To mitigate the impact of Faraday rotation on satellite observations, the third LSE measure uses measurement combinations invariant under the Faraday rotation. For Aquarius, the expected RMS SSS (sea surface salinity) error will be less than about 0.2 psu for low winds, and increases to 0.3 psu at 25 m/s wind speed

  13. Intracellular sensing of complement C3 activates cell autonomous immunity

    PubMed Central

    Tam, Jerry C.H.; Bidgood, Susanna R.; McEwan, William A.; James, Leo C.

    2014-01-01

    Pathogens traverse multiple barriers during infection including cell membranes. Here we show that during this transition pathogens carry covalently attached complement C3 into the cell, triggering immediate signalling and effector responses. Sensing of C3 in the cytosol activates MAVS-dependent signalling cascades and induces proinflammatory cytokine secretion. C3 also flags viruses for rapid proteasomal degradation, thereby preventing their replication. This system can detect both viral and bacterial pathogens but is antagonized by enteroviruses, such as rhinovirus and poliovirus, which cleave C3 using their 3C protease. The antiviral Rupintrivir inhibits 3C protease and prevents C3 cleavage, rendering enteroviruses susceptible to intracellular complement sensing. Thus, complement C3 allows cells to detect and disable pathogens that have invaded the cytosol. PMID:25190799

  14. Intracellular sensing of complement C3 activates cell autonomous immunity.

    PubMed

    Tam, Jerry C H; Bidgood, Susanna R; McEwan, William A; James, Leo C

    2014-09-01

    Pathogens traverse multiple barriers during infection, including cell membranes. We found that during this transition, pathogens carried covalently attached complement C3 into the cell, triggering immediate signaling and effector responses. Sensing of C3 in the cytosol activated mitochondrial antiviral signaling (MAVS)-dependent signaling cascades and induced proinflammatory cytokine secretion. C3 also flagged viruses for rapid proteasomal degradation, preventing their replication. This system could detect both viral and bacterial pathogens but was antagonized by enteroviruses, such as rhinovirus and poliovirus, which cleave C3 using their 3C protease. The antiviral rupintrivir inhibited 3C protease and prevented C3 cleavage, rendering enteroviruses susceptible to intracellular complement sensing. Thus, complement C3 allows cells to detect and disable pathogens that have invaded the cytosol. PMID:25190799

  15. Rapid Synthesis and Antiviral Activity of (Quinazolin-4-Ylamino)Methyl-Phosphonates Through Microwave Irradiation

    PubMed Central

    Luo, Hui; Hu, Deyu; Wu, Jian; He, Ming; Jin, Linhong; Yang, Song; Song, Baoan

    2012-01-01

    This study describes the simple synthesis of new (quinazolin-4-ylamino) methylphosphonates via microwave irradiation. Substituted-2-aminobenzonitrile reacted with 1,1-dimethoxy-N,N-dimethylmethanamine at a reflux condition to obtain N′-(substituted-2-cyanophenyl)-N,N-dimethylformamidine (1). The subsequent reaction of this intermediate product with α-aminophosphonate (2) in a solution containing glacial acetic acid in 2-propanol through microwave irradiation resulted in the formation of (quinazolin-4-ylamino)methyl-phosphonate derivatives 3a to 3x, which were unequivocally characterized by the spectral data and elemental analysis. The influence of the reaction conditions on the yield of 3a was investigated to optimize the synthetic conditions. The relative optimal conditions for the synthesis of 3a include a 1:1 molar ratio of N′-(2-cyanophenyl)-N,N-dimethylformamidine to diethyl amino(phenyl)methylphosphonate and a 4:1 volume ratio of isopropanol to HOAc in the solvent mixture, at a reaction temperature of 150 °C, with a microwave power of 100 W and a corresponding pressure of 150 psi for 20 min in the microwave synthesizer. The yield of 3a was approximately 79%, whereas those of 3b to 3x were approximately 77% to 86%. Some of the synthesized compounds displayed weak to good anti-Tobacco mosaic virus (TMV) activity. PMID:22837660

  16. A change detection approach to flood mapping in urban areas using very high-resolution microwave remote sensing imagery

    NASA Astrophysics Data System (ADS)

    Giustarini, L.; Hostache, R.; Matgen, P.; Schumann, G.; Bates, P. D.; Mason, D. C.

    2012-04-01

    Very high-resolution Synthetic Aperture Radar sensors represent an alternative to aerial photography for delineating floods in built-up environments where flood risk is highest. However, even with currently available SAR image resolutions of 3 m and higher, signal returns from man-made structures hamper the accurate mapping of flooded areas. Enhanced image processing algorithms and a better exploitation of image archives are required to facilitate the use of microwave remote sensing data for monitoring flood dynamics in urban areas. This work presents a new way to efficiently process SAR data for enhanced flood detection. The purpose is to develop a fully automatic image classification method based on image statistics that can be applied to all existing SAR data sets and to different types of flooded regions, including urban settlements. A hybrid methodology combining radiometric thresholding, region growing and change detection is introduced as an approach enabling the automated, objective and reliable flood extent extraction from very high-resolution urban SAR images. The method is based on the calibration of a statistical distribution of "open water" backscatter values inferred from SAR images of floods. SAR images acquired during dry conditions enable the identification of i) areas that are located in "shadow" regions and are therefore not visible to the sensor and ii) areas that systematically behave as specular reflectors (e.g. smooth tarmac, permanent water bodies). Change detection with respect to a pre-flood reference image thereby reduces over-detection of inundated areas. A case study of the July 2007 Severn River flood (UK) observed by the very high-resolution SAR sensor on board TerraSAR-X as well as airborne photography highlights advantages and limitations of the proposed method. We conclude that the fully automated SAR-based flood mapping technique overcomes some limitations of state-of-the-art methods normally used. However, further technological

  17. Structure and activity of the acid-sensing ion channels

    PubMed Central

    Sherwood, Thomas W.; Frey, Erin N.

    2012-01-01

    The acid-sensing ion channels (ASICs) are a family of proton-sensing channels expressed throughout the nervous system. Their activity is linked to a variety of complex behaviors including fear, anxiety, pain, depression, learning, and memory. ASICs have also been implicated in neuronal degeneration accompanying ischemia and multiple sclerosis. As a whole, ASICs represent novel therapeutic targets for several clinically important disorders. An understanding of the correlation between ASIC structure and function will help to elucidate their mechanism of action and identify potential therapeutics that specifically target these ion channels. Despite the seemingly simple nature of proton binding, multiple studies have shown that proton-dependent gating of ASICs is quite complex, leading to activation and desensitization through distinct structural components. This review will focus on the structural aspects of ASIC gating in response to both protons and the newly discovered activators GMQ and MitTx. ASIC modulatory compounds and their action on proton-dependent gating will also be discussed. This review is dedicated to the memory of Dale Benos, who made a substantial contribution to our understanding of ASIC activity. PMID:22843794

  18. Renewable phenols production by catalytic microwave pyrolysis of Douglas fir sawdust pellets with activated carbon catalysts.

    PubMed

    Bu, Quan; Lei, Hanwu; Wang, Lu; Wei, Yi; Zhu, Lei; Liu, Yupeng; Liang, Jing; Tang, Juming

    2013-08-01

    The effects of different activated carbon (AC) catalysts based on various carbon sources on products yield and chemical compositions of upgraded pyrolysis oils were investigated using microwave pyrolysis of Douglas fir sawdust pellets. Results showed that high amounts of phenols were obtained (74.61% and 74.77% in the upgraded bio-oils by DARCO MRX (wood based) and DARCO 830 (lignite coal based) activated carbons, respectively). The catalysts recycling test of the selected catalysts indicated that the carbon catalysts can be reused for at least 3-4 times and produced high concentrations of phenol and phenolic compounds. The chemical reaction mechanism for phenolics production during microwave pyrolysis of biomass was analyzed. PMID:23765005

  19. Implications of RFI at L-Band on Passive Microwave Remote Sensing of Soil Moisture from Space: Experience with ESTAR During SGP97

    NASA Technical Reports Server (NTRS)

    LeVine, David M.

    2000-01-01

    Passive microwave remote sensing in the protected band at 1.413 GHz (L-band) is important for monitoring parameters of the ocean and land surface such as soil moisture and sea surface salinity. These parameters are needed for understanding energy exchange between the surface and atmosphere and therefore are important for improving our understanding of weather and climate change. Although the band at 1.413 GHz is protected for passive use, airborne radiometers experience problems with RFI. For example, during the Southern Great Plains Experiment (1997) the ESTAR radiometer experienced significant RFI associated with airports, presumably air traffic control radar. This is a potential problem for future sensors in space planned for remote sensing of the earth surface in this frequency band.

  20. Wageningen UR Unmanned Aerial Remote Sensing Facility - Overview of activities

    NASA Astrophysics Data System (ADS)

    Bartholomeus, Harm; Keesstra, Saskia; Kooistra, Lammert; Suomalainen, Juha; Mucher, Sander; Kramer, Henk; Franke, Jappe

    2016-04-01

    To support environmental management there is an increasing need for timely, accurate and detailed information on our land. Unmanned Aerial Systems (UAS) are increasingly used to monitor agricultural crop development, habitat quality or urban heat efficiency. An important reason is that UAS technology is maturing quickly while the flexible capabilities of UAS fill a gap between satellite based and ground based geo-sensing systems. In 2012, different groups within Wageningen University and Research Centre have established an Unmanned Airborne Remote Sensing Facility. The objective of this facility is threefold: a) To develop innovation in the field of remote sensing science by providing a platform for dedicated and high-quality experiments; b) To support high quality UAS services by providing calibration facilities and disseminating processing procedures to the UAS user community; and c) To promote and test the use of UAS in a broad range of application fields like habitat monitoring, precision agriculture and land degradation assessment. The facility is hosted by the Laboratory of Geo-Information Science and Remote Sensing (GRS) and the Department of Soil Physics and Land Management (SLM) of Wageningen University together with the team Earth Informatics (EI) of Alterra. The added value of the Unmanned Aerial Remote Sensing Facility is that compared to for example satellite based remote sensing more dedicated science experiments can be prepared. This includes for example higher frequent observations in time (e.g., diurnal observations), observations of an object under different observation angles for characterization of BRDF and flexibility in use of camera's and sensors types. In this way, laboratory type of set ups can be tested in a field situation and effects of up-scaling can be tested. In the last years we developed and implemented different camera systems (e.g. a hyperspectral pushbroom system, and multispectral frame cameras) which we operated in projects all

  1. Active microwave investigation of snowpacks: Experimental documentation, Colorado 1979-1980

    NASA Technical Reports Server (NTRS)

    Stiles, W. H.; Ulaby, F. T.; Aslam, A.; Abdelrazik, M.

    1981-01-01

    During the winter of 1979-1980, the University of Kansas Microwave Active Spectrometer systems measured the backscattering properties of snowpacks under varying conditions at four test sites in Colorado. In addition to the radar data over 1-35 GHz, ground-truth measurements of the atmospheric, snow, and soil characteristics were obtained for each radar data set. The test sites, data acquisition procedures, and data that were acquired in this experiment are presented and described.

  2. Microwave-assisted extraction of polysaccharides from Yupingfeng powder and their antioxidant activity

    PubMed Central

    Wang, Dan; Zhang, Bi-Bo; Qu, Xiao-Xia; Gao, Feng; Yuan, Min-Yong

    2015-01-01

    Background: Microwave-assisted reflux extraction of polysaccharides YPF-P from the famous Chinese traditional drug, Yupingfeng powder, optimization of extracting conditions and evaluation of their antioxidant activity were conducted in this study. Results: Single factor effect trends were achieved through yields and contends of YPF-P obtained from different extracting conditions. Then through a three-level, four-variable Box-Behnken design of response surface methodology adopting yield as response, the optimal conditions were determined as follows: Material/solvent ratio 1:23.37, microwave power 560 W, Extraction temperature 64°C, and extraction time 9.62 min. Under the optimal conditions, the YPF-P extraction yield was 3.23%, and its content was detected as 38.52%. In antioxidant assays, the YPF-P was tested to possess 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities with an IC50 value of 0.262 mg/ml. In addition, YPF-P was also proved to have relatively low ferric reducing antioxidant power (FRAP), compared to Vc, through FRAP assay. Conclusion: In the microwave assisted reflux extraction research, good YPF-P yield was achieved from materials with relatively low YPF-P content. And for the first time, both DPPH and FRAP assays were conducted on YPF-P, which proved that the antioxidant activity of YPF-P contributed to the functions of this medicine. PMID:26246730

  3. Peroxide-assisted microwave activation of pyrolysis char for adsorption of dyes from wastewater.

    PubMed

    Nair, Vaishakh; Vinu, R

    2016-09-01

    In this study, mesoporous activated biochar with high surface area and controlled pore size was prepared from char obtained as a by-product of pyrolysis of Prosopis juliflora biomass. The activation was carried out by a simple process that involved H2O2 treatment followed by microwave pyrolysis. H2O2 impregnation time and microwave power were optimized to obtain biochar with high specific surface area and high adsorption capacity for commercial dyes such as Remazol Brilliant Blue and Methylene Blue. Adsorption parameters such as initial pH of the dye solution and adsorbent dosage were also optimized. Pore size distribution, surface morphology and elemental composition of activated biochar were thoroughly characterized. H2O2 impregnation time of 24h and microwave power of 600W produced nanostructured biochar with narrow and deep pores of 357m(2)g(-1) specific surface area. Langmuir and Langmuir-Freundlich isotherms described the adsorption equilibrium, while pseudo second order model described the kinetics of adsorption. PMID:27268436

  4. Drimendiol, a drimane sesquiterpene with quorum sensing inhibition activity.

    PubMed

    Paza, Cristian; Cárcamo, Gerardo; Silva, Mario; Becerra, José; Urrutia, Homero; Sossa, Katherine

    2013-02-01

    Quorum sensing (QS) is a regulatory mechanism that enables bacteria to make collective decisions such as an increase in virulence factors and biofilm production. Inhibitors of QS are important research tools in the discovery of new potential anti-bacterial agents. Polygodial, drimenol and drimendiol are drimane sesquiterpenoids isolated from Drimys winteri, a Chilean native tree. Their QS activity, when tested on Chromobacterium violaceum ATCC 12472, showed that drimendiol is an inhibitor of QS, decreasing violaceine production in C violaceum and decreasing biofilm formation of Pseudomonas syringae strains. Consequently it increased the biocide effects of CuSO4 on biofilms of P. syringae. PMID:23513712

  5. Remote sensing of environmental impact of land use activities

    NASA Technical Reports Server (NTRS)

    Paul, C. K.

    1977-01-01

    The capability to monitor land cover, associated in the past with aerial film cameras and radar systems, was discussed in regard to aircraft and spacecraft multispectral scanning sensors. A proposed thematic mapper with greater spectral and spatial resolutions for the fourth LANDSAT is expected to usher in new environmental monitoring capability. In addition, continuing improvements in image classification by supervised and unsupervised computer techniques are being operationally verified for discriminating environmental impacts of human activities on the land. The benefits of employing remote sensing for this discrimination was shown to far outweigh the incremental costs of converting to an aircraft-satellite multistage system.

  6. CARER: Efficient Dynamic Sensing for Continuous Activity Monitoring

    PubMed Central

    Au, Lawrence K.; Bui, Alex A.T.; Batalin, Maxim A.; Xu, Xiaoyu; Kaiser, William J.

    2016-01-01

    Advancement in wireless health sensor systems has triggered rapidly expanding research in continuous activity monitoring for chronic disease management or promotion and assessment of physical rehabilitation. Wireless motion sensing is increasingly important in treatments where remote collection of sensor measurements can provide an in-field objective evaluation of physical activity patterns. The well-known challenge of limited operating lifetime of energy-constrained wireless health sensor systems continues to present a primary limitation for these applications. This paper introduces CARER, a software system that supports a novel algorithm that exploits knowledge of context and dynamically schedules sensor measurement episodes within an energy consumption budget while ensuring classification accuracy. The sensor selection algorithm in the CARER system is based on Partially Observable Markov Decision Process (POMDP). The parameters for the POMDP algorithm can be obtained through standard maximum likelihood estimation. Sensor data are also collected from multiple locations of the subjects body, providing estimation of an individual's daily activity patterns. PMID:22254783

  7. Polyphenolic contents and antioxidant activities of Lawsonia inermis leaf extracts obtained by microwave-assisted hydrothermal method.

    PubMed

    Zohourian, Tayyebeh Haleh; Quitain, Armando T; Sasaki, Mitsuru; Goto, Motonobu

    2011-01-01

    Extracts obtained by microwave-assisted hydrothermal extraction of Lawsonia inermis leaves were evaluated for the presence of polyphenolic compounds and antioxidant activities. Extraction experiments were performed in temperature-controlled mode at a range of 100 to 200 degrees C, and extraction time of 5 to 30 min, and microwave-controlled mode at a power from 300-700 W, in irradiation time of 30 to 120 s. Polyphenolic contents were measured using Folin-Ciocalteau method, while antioxidant properties were analyzed using DPPH radical scavenging activities (RSA) expressed in BHA equivalents. Results showed that best values of RSA were obtained at mild temperature range of 100-120 degrees C. Controlling microwave power at short irradiation time gave better results than temperature-controlled treatment as well. Furthermore, comparison with the result obtained at room temperature confirmed that the use of microwave was more effective for extracting polar components that normally possess higher antioxidant activities. PMID:24428109

  8. Influence of microwave parameters and water activity on radical generation in rice starch.

    PubMed

    Fan, Daming; Liu, Yixiao; Hu, Bo; Lin, Lufen; Huang, Luelue; Wang, Liyun; Zhao, Jianxin; Zhang, Hao; Chen, Wei

    2016-04-01

    Radical generation in rice starch under microwave treatment as well as the related chemical bond changes were investigated by electron paramagnetic resonance (EPR) and Raman spectroscopy. Samples with water activity of 0.4 and 0.7 have been treated and analyzed. It was found that microwave power level and water content could influence the amount of radicals along with the radical components and their contribution. Raman spectra showed corresponding changes in vibrational features of chemical bonds. During storage the signal intensity started to drop after a short period of increase. Rice starch radicals were relatively stable and could exist a long time in room temperature. Through signal simulation, 3 main components were separated from the original spectra and the evolving process was investigated. The main component was the radical located on C1 position in the glucose ring. PMID:26593462

  9. Slow potentials and spike unit activity of the cerebral cortex of rabbits exposed to microwaves

    SciTech Connect

    Chizhenkova, R.A.

    1988-01-01

    Unanesthetized rabbits exposed to 12.5-cm microwaves at a field intensity of 40 mW/cm/sup 2/ in the region of the head showed an increase in the number of slow waves and spindle-shaped firings in the EEG and a change in the discharge frequency of neurons in the visual cortex in 41-52% of the cases. An enhancement of the evoked response of visual cortex neurons to light was observed in 61% of the cases and a facilitation of the driving response in 80% of all cases. It is concluded that the evoked response is a more sensitive indicator of the microwave effect than background activity. The effects of the fields were most distinctly observed with the driving response.

  10. NASA Activities as they Relate to Microwave Technology for Aerospace Communications Systems

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.

    2011-01-01

    This presentation discusses current NASA activities and plans as they relate to microwave technology for aerospace communications. The presentations discusses some examples of the aforementioned technology within the context of the existing and future communications architectures and technology development roadmaps. Examples of the evolution of key technology from idea to deployment are provided as well as the challenges that lay ahead regarding advancing microwave technology to ensure that future NASA missions are not constrained by lack of communication or navigation capabilities. The presentation closes with some examples of emerging ongoing opportunities for establishing collaborative efforts between NASA, Industry, and Academia to encourage the development, demonstration and insertion of communications technology in pertinent aerospace systems.

  11. Active region studies with coordinated SOHO, microwave, and magnetograph observations

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    1992-01-01

    The scientific justification for an observing campaign to study the quantitative magnetic and plasma properties of coronal loops in active regions is presented. The SOHO (Solar and Heliospheric Observatory) instruments of primary relevance are CDS (Coronal Diagnostic Spectrometer), EIT, SUMER (Solar Ultraviolet Measurement of Emitted Radiation), and MDI. The primary ground based instruments would be the VLA (Very Large Array), the Owens Valley Radio Observatory, and vector and longitudinal field magnetographs. Similar campaigns have successfully been carried out with the Solar Maximum Mission x-ray polychromator and the Soft X-ray Imaging Sounding Rocket Payload (CoMStOC '87), the Goddard Solar EUV Rocket Telescope and Spectrograph, the Lockheed Solar Plasma Diagnostics Experiment rocket payload, and the Soft X-ray Telescope in Yohkoh (CoMStoc '92). The scientific payoff from such a campaign is discussed in light of the results from these previous campaigns.

  12. Compact Microwave Fourier Spectrum Analyzer

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

    2009-01-01

    A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.

  13. Soft Active Materials for Actuation, Sensing, and Electronics

    NASA Astrophysics Data System (ADS)

    Kramer, Rebecca Krone

    Future generations of robots, electronics, and assistive medical devices will include systems that are soft and elastically deformable, allowing them to adapt their morphology in unstructured environments. This will require soft active materials for actuation, circuitry, and sensing of deformation and contact pressure. The emerging field of soft robotics utilizes these soft active materials to mimic the inherent compliance of natural soft-bodied systems. As the elasticity of robot components increases, the challenges for functionality revert to basic questions of fabrication, materials, and design - whereas such aspects are far more developed for traditional rigid-bodied systems. This thesis will highlight preliminary materials and designs that address the need for soft actuators and sensors, as well as emerging fabrication techniques for manufacturing stretchable circuits and devices based on liquid-embedded elastomers.

  14. Applications of airborne remote sensing in atmospheric sciences research

    NASA Technical Reports Server (NTRS)

    Serafin, R. J.; Szejwach, G.; Phillips, B. B.

    1984-01-01

    This paper explores the potential for airborne remote sensing for atmospheric sciences research. Passive and active techniques from the microwave to visible bands are discussed. It is concluded that technology has progressed sufficiently in several areas that the time is right to develop and operate new remote sensing instruments for use by the community of atmospheric scientists as general purpose tools. Promising candidates include Doppler radar and lidar, infrared short range radiometry, and microwave radiometry.

  15. Microwave discharge electrodeless lamps (MDEL). Part IV. Novel self-ignition system incorporating metallic microwave condensing cones to activate MDELs in photochemical reactions.

    PubMed

    Horikoshi, Satoshi; Tsuchida, Akihiro; Sakai, Hideki; Abe, Masahiko; Sato, Susumu; Serpone, Nick

    2009-11-01

    A metallic condensing cone that concentrates microwave radiation (equivalent to an optical lens) has been developed and used as part of a system to activate a microwave discharge electrodeless lamp (MDEL) in the oxidative treatment of wastewaters by aiding the novel self-ignition of the lamp on irradiation at low microwave power levels. This approach to self-ignition can potentially lead to considerable energy savings in such treatments. System performance was examined for the ignition power of microwaves of such MDEL devices in water, whose usefulness was assessed by investigating the photolytic transformation of aqueous solutions of representatives of three classes of contaminants: chlorinated phenols, herbicides and endocrine disruptors, specifically 4-chlorophenol (4-CP), 2,4-dichlorophenoxyacetic acid (2,4-D) and 4,4'-isopropylidenediphenol (bisphenol-A; BPA), respectively, taken as model wastewaters in air-equilibrated, in oxygen-saturated and in TiO2-containing aqueous media. The results are discussed in terms of the dynamics of the photo-induced degradation processes. PMID:19862422

  16. Frequency Based Volcanic Activity Detection through Remotely Sensed Data

    NASA Astrophysics Data System (ADS)

    Worden, A. K.; Dehn, J.; Webley, P. W.

    2015-12-01

    Satellite remote sensing has proved to offer a useful and relatively inexpensive method for monitoring large areas where field work is logistically unrealistic, and potentially dangerous. Current sensors are able to detect the majority of explosive volcanic activity; those that tend to effect and represent larger scale changes in the volcanic systems, eventually relating to ash producing periods of extended eruptive activity, and effusive activity. As new spaceborne sensors are developed, the ability to detect activity improves so that a system to gauge the frequency of volcanic activity can be used as a useful monitoring tool. Four volcanoes were chosen for development and testing of a method to monitor explosive activity: Stromboli (Italy); Shishaldin and Cleveland (Alaska, USA); and Karymsky (Kamchatka, Russia). Each volcano studied had similar but unique signatures of pre-cursory and eruptive activity. This study has shown that this monitoring tool could be applied to a wide range of volcanoes and still produce useful and robust data. Our method deals specifically with the detection of small scale explosive activity. The method described here could be useful in an operational setting, especially at remote volcanoes that have the potential to impact populations, infrastructure, and the aviation community. A number of important factors will affect the validity of application of this method. They are: (1) the availability of a continuous and continually populated dataset; (2) appropriate and reasonable sensor resolutions; (3) a recorded history of the volcano's previous activity; and, if available, (4) some ground-based monitoring system. We aim to develop the method further to be able to capture and evaluate the frequency of other volcanic processes such as lava flows, phreatomagmatic eruptions and dome growth and collapse. The work shown here has served to illustrate the capability of this method and monitoring tool for use at remote, un-instrumented volcanoes.

  17. Microwave Sintering and Optical Properties of Sm3+-Activated KSrPO4 Phosphors

    NASA Astrophysics Data System (ADS)

    Wu, Chun-Sen; Lin, Bor-Tsuen; Jean, Ming-Der

    2014-02-01

    The microwave sintering and photoluminescence properties of KSr1- x PO4: xSm3+ phosphors have been investigated. KSrPO4 phosphates activated by various concentrations of Sm3+ ions ( x = 0.007, 0.009, 0.01, 0.03) were microwave sintered at 1200°C for 3 h under air atmosphere. x-Ray diffraction patterns showed that all phosphor samples exhibited a single phase without any extraneous phases. Scanning electron microscopy images showed that the particle size increased with the Sm3+ concentration and that the particle morphology was fine and uniform. The photoluminescence results showed that a concentration quenching effect occurred when the concentration of Sm3+ ions reached x = 0.01. Decay time measurement results showed that the lifetime decreased gradually from 3.12 ms to 2.34 ms as the Sm3+ concentration increased. All the chromaticity ( x, y) values of the microwave-sintered KSrPO4:Sm3+ phosphors were located in the red region (0.57, 0.41).

  18. Microwave hydrothermal synthesis of AgInS{sub 2} with visible light photocatalytic activity

    SciTech Connect

    Zhang, Wenjuan; Li, Danzhen; Chen, Zhixin; Sun, Meng; Li, Wenjuan; Lin, Qiang; Fu, Xianzhi

    2011-07-15

    Highlights: {yields} AgInS{sub 2} nanoparticles were synthesized by a microwave hydrothermal method. {yields} This method involves no organic solvents, catalysts, or surfactants. {yields} AgInS{sub 2} showed higher activity for photocatalytic degradation MO than TiO{sub 2-x}N{sub x}. {yields} Holes, O{sub 2}{center_dot}{sup -}, and H{sub 2}O{sub 2} played an important role in the photocatalytic process. -- Abstract: AgInS{sub 2} nanoparticles with superior visible light photocatalytic activity were successfully synthesized by a microwave hydrothermal method. This method is a highly efficient and rapid route that involves no organic solvents, catalysts, or surfactants. The photocatalytic activity of AgInS{sub 2} nanoparticles was investigated through the degradation of dyes under visible light irradiation. Compared with TiO{sub 2-x}N{sub x}, AgInS{sub 2} has exhibited a superior activity for photocatalytic degradation MO under the same condition. The experiment results showed that superoxide radicals (O{sub 2}{center_dot}{sup -}), hydrogen peroxides (H{sub 2}O{sub 2}) and holes (h{sup +}) were the mainly active species for the degradation of organic pollutants over AgInS{sub 2}. Through the determination of flat band potential, the energy band structure of the sample was obtained. A possible mechanism for the degradation of organic pollutant over AgInS{sub 2} was proposed.

  19. Satellite passive microwave remote sensing for estimating diurnal variation of leaf water content, as a proxy of evapotranspiration, in the Dry Chaco Forest, Argentina

    NASA Astrophysics Data System (ADS)

    Barraza Bernadas, V.; Grings, F.; Ferrazzoli, P.; Carbajo, A.; Fernandez, R.; Karszenbaum, H.

    2012-12-01

    Evapotranspiration (ET) is a key component of water cycle, which is strongly linked with environmental condition and vegetation functioning. Since it is very difficult to robustly estimate it from remote sensing data at regional scale it is usually inferred from other proxies using water balance. This work describes a procedure to estimate ET in a dry forest by monitoring diurnal variation of leaf water content (LWC), using multitemporal passive microwave remote sensing observations. Hourly observations provide the opportunity to monitor repetitive diurnal variations of passive microwave observations, which can only be accounted by changes in LWC (which is itself related to water vapor that enters to the atmosphere from land surface). To this end, we calculated the vegetation frequency index (FI) as FI= 2*(TBKa-TBX)/ ((TBKa +TBX)), where TBKa and TBX indicate brightness temperatures at 37 and 10.6 GHz respectively. There is both theoretical and experimental evidence that link this index to microwave to LWC. The index was computed for vertical polarization, because it presents higher correlation with vegetation state. At diurnal temporal scale, changes in LWC are commonly very small. Nevertheless, it was previously shown that passive remote sensing data (FI computed using Ku and Ka bands) acquired at different hours can be used to estimate the seasonal changes in ET. In this work, we present a procedure based on the hourly changes of FI, which are interpreted as changes in LWC. In order to present a quantitative estimation, the discrete forest model described in (Ferrazzoli and Guerriero, 1996) has been used to simulate the variations of FI with LWC. To illustrate the procedure, AMSR-E and WINDSAT data from 2007-2009 at X and Ka bands were used, and up to four observations per day at four different local times (2.30 am, 7.00 am, 2.30 pm and 7.00 pm) were analyzed. The region addressed is the area of the Dry Chaco forest located in Bermejo River Basin in Argentina

  20. Microwave Assisted Synthesis, Antifungal Activity, and DFT Study of Some Novel Triazolinone Derivatives

    PubMed Central

    Sun, Na-Bo; Jin, Jian-Zhong; He, Fang-Yue

    2015-01-01

    A series of some novel 1,2,4-triazol-5(4H)-one derivatives were designed and synthesized under microwave irradiation via multistep reaction. The structures of 1,2,4-triazoles were confirmed by 1H NMR, MS, FTIR, and elemental analysis. The antifungal activities of 1,2,4-triazoles were determined. The antifungal activity results indicated that the compounds 5c, 5f, and 5h exhibited good activity against Pythium ultimum, and the compounds 5b and 5c displayed good activity against Corynespora cassiicola. Theoretical calculation of the compound 5c was carried out with B3LYP/6-31G (d). The full geometry optimization was carried out using 6-31G(d) basis set, and the frontier orbital energy and electrostatic potential were discussed, and the structure-activity relationship was also studied. PMID:25861651

  1. Application of active spaceborne remote sensing for understanding biases between passive cloud water path retrievals

    NASA Astrophysics Data System (ADS)

    Lebsock, Matthew; Su, Hui

    2014-07-01

    Bias between the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) version 2 and the Moderate Resolution Imaging Spectroradiometer (MODIS) collection 5.1 cloud liquid water path (Wc) products are explored with the aid of coincident active observations from the CloudSat radar and the CALIPSO lidar. In terms of detection, the active observations provide precise separation of cloudy from clear sky and precipitating from nonprecipitating clouds. In addition, they offer a unique quantification of precipitation water path (Wp) in warm clouds. They also provide an independent quantification of Wc that is based on an accurate surface reference technique, which is an independent arbiter between the two passive approaches. The results herein establish the potential for CloudSat and CALIPSO to provide an independent assessment of bias between the conventional passive remote sensing methods from reflected solar and emitted microwave radiation. After applying a common data filter to the observations to account for sampling biases, AMSR-E is biased high relative to MODIS in the global mean by 26.4 gm-2. The RMS difference in the regional patterns is 32.4 gm-2, which highlights a large geographical dependence in the bias which is related to the tropical transitions from stratocumulus to cumulus cloud regimes. The contributions of four potential sources for this bias are investigated by exploiting the active observations: (1) bias in MODIS related to solar zenith angle dependence accounts for -2.3 gm-2, (2) bias in MODIS due to undersampling of cloud edges accounts for 4.2 gm-2, (3) a wind speed and water vapor-dependent "clear-sky biase" in the AMSR-E retrieval accounts for 6.3 gm-2, and (4) evidence suggests that much of the remaining 18 gm-2 bias is related to the assumed partitioning of the observed emission signal between cloud and precipitation water in the AMSR-E retrieval. This is most evident through the correlations between the regional mean patterns of Wp and the Wc

  2. Polarity-enhanced gas-sensing performance of Au-loaded ZnO nanospindles synthesized via precipitation and microwave irradiation

    NASA Astrophysics Data System (ADS)

    Li, Yan; Lv, Tan; Zhao, Fang-Xian; Lian, Xiao-Xue; Zou, Yun-Ling; Wang, Qiong

    2016-05-01

    Loading noble metal and exploring suitable morphology to achieve excellent gas-sensing performance is very crucial for the fabrication of gas sensors. We have successfully synthesized Au-loaded ZnO (Au/ZnO) nanospindles (NSs) through a really facile procedure involving a precipitation and subsequent microwave irradiation. The as-prepared products have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The formation and gas-sensing mechanism of Au/ZnO NSs were discussed. The SEM micrographs revealed an interesting morphological evolution of the Au/ZnO NSs with Au-loading content ranging from 0 at. % to 7 at. %. The nanostructures were employed for gas-sensing measurement toward various gases. It indicated that the Au/ZnO NSs based sensor showed a highly enhanced response (226.81) to 400 ppm acetone gas at a relatively low working temperature (270°C), and exhibited a fast response (1 s) and recovery speed (10 s). The highly enhanced acetone gas sensitivity of Au/ZnO NSs based sensor could be attributed to its enhanced polarity owing to the peculiar morphology, Schottcky barriers, as well as catalytic effect of Au NPs. [Figure not available: see fulltext.

  3. Sensing and antibacterial activity of imidazolium-based conjugated polydiacetylenes.

    PubMed

    Lee, Songyi; Cheng, Hua; Chi, Meiying; Xu, Qingling; Chen, Xiaoqiang; Eom, Chi-Yong; James, Tony D; Park, Sungsu; Yoon, Juyoung

    2016-03-15

    In the current study, we report the first example of polydiacetylenes (PDAs), where our PDA-based system acts as both a sensing probe and killer for bacteria. The contact of imidazolium and imidazole-derived PDA with various bacterial strains including MRSA (methicillin-resistant Staphylococcus aureus) and ESBL-EC (extended-spectrum β-lactamase-producing Escherichia coli) results in a distinct blue-to-red colorimetric change of the solution as well as a rapid disruption of the bacterial membrane, which is demonstrated by transmission electron microscopy and confocal microscopy. Zeta potential analysis supports that antibacterial activity of the PDA solution originates from an electrostatic interaction between the negatively charged bacterial cell surface and the positively charged polymers. These results suggest that the PDA has a great potential to carry out the dual roles of a probe and killer for bacteria. PMID:26547428

  4. Active Sensing and Its Application to Sensor Node Reconfiguration

    PubMed Central

    Lee, Sooyong

    2014-01-01

    This paper presents a perturbation/correlation-based active sensing method and its application to sensor node configuration for environment monitoring. Sensor networks are widely used as data measurement tools, especially in dangerous environments. For large scale environment monitoring, a large number of nodes is required. For optimal measurements, the placement of nodes is very important. Nonlinear spring force-based configuration is introduced. Perturbation/correlation-based estimation of the gradient is developed and it is much more robust because it does not require any differentiation. An algorithm for tuning the stiffness using the estimated gradient for node reconfiguration is presented. The performance of the proposed algorithm is discussed with simulation results. PMID:25299949

  5. Non-Invasive UWB Sensing of Astronauts' Breathing Activity

    PubMed Central

    Baldi, Marco; Cerri, Graziano; Chiaraluce, Franco; Eusebi, Lorenzo; Russo, Paola

    2015-01-01

    The use of a UWB system for sensing breathing activity of astronauts must account for many critical issues specific to the space environment. The aim of this paper is twofold. The first concerns the definition of design constraints about the pulse amplitude and waveform to transmit, as well as the immunity requirements of the receiver. The second issue concerns the assessment of the procedures and the characteristics of the algorithms to use for signal processing to retrieve the breathing frequency and respiration waveform. The algorithm has to work correctly in the presence of surrounding electromagnetic noise due to other sources in the environment. The highly reflecting walls increase the difficulty of the problem and the hostile scenario has to be accurately characterized. Examples of signal processing techniques able to recover breathing frequency in significant and realistic situations are shown and discussed. PMID:25558995

  6. Sensitivity of Active and Passive Microwave Observations to Soil Moisture during Growing Corn

    NASA Astrophysics Data System (ADS)

    Judge, J.; Monsivais-Huertero, A.; Liu, P.; De Roo, R. D.; England, A. W.; Nagarajan, K.

    2011-12-01

    Soil moisture (SM) in the root zone is a key factor governing water and energy fluxes at the land surface and its accurate knowledge is critical to predictions of weather and near-term climate, nutrient cycles, crop-yield, and ecosystem productivity. Microwave observations, such as those at L-band, are highly sensitive to soil moisture in the upper few centimeters (near-surface). The two satellite-based missions dedicated to soil moisture estimation include, the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission and the planned NASA Soil Moisture Active/Passive (SMAP) [4] mission. The SMAP mission will include active and passive sensors at L-band to provide global observations of SM, with a repeat coverage of every 2-3 days. These observations can significantly improve root zone soil moisture estimates through data assimilation into land surface models (LSMs). Both the active (radar) and passive (radiometer) microwave sensors measure radiation quantities that are functions of soil dielectric constant and exhibit similar sensitivities to SM. In addition to the SM sensitivity, radar backscatter is highly sensitive to roughness of soil surface and scattering within the vegetation. These effects may produce a much larger dynamic range in backscatter than that produced due to SM changes alone. In this study, we discuss the field observations of active and passive signatures of growing corn at L-band from several seasons during the tenth Microwave, Water and Energy Balance Experiment (MicroWEX-10) conducted in North Central Florida, and to understand the sensitivity of these signatures to soil moisture under dynamic vegetation conditions. The MicroWEXs are a series of season-long field experiments conducted during the growing seasons of sweet corn, cotton, and energy cane over the past six years (for example, [22]). The corn was planted on July 5 and harvested on September 23, 2011 during MicroWEX-10. The size of the field was 0.04 km2 and the soils

  7. Effect of microphysics scheme in cloud resolving models in passive microwave remote sensing of precipitation over ocean

    NASA Astrophysics Data System (ADS)

    Kim, Ju-Hye; Shin, Dong-Bin; Kummerow, Christian

    2014-05-01

    Physically-based rainfall retrievals from passive microwave sensors often make use of cloud resolving models (CRMs) to build a-priori databases of potential rain structures. Each CRM, however, has its own assumptions on the cloud microphysics. Hence, approximated microphysics may cause uncertainties in the a-priori information resulting in inaccurate rainfall estimates. This study first builds a-priori databases by combining the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) observations and simulations from the Weather Research and Forecasting (WRF) model with six different cloud microphysics schemes. The microphysics schemes include the Purdue Lin (LIN), WRF-Single-Moment 6 (WSM6), Goddard Cumulus Ensemble (GCE), Thompson (THOM), WRF-Double-Moment 6 (WDM6), and Morrison (MORR) schemes. As expected, the characteristics of the a-priori databases are inherited from the individual cloud microphysics schemes. There are several distinct differences in the databases. Particularly, excessive graupel and snow exist with the LIN and THOM schemes, while more rainwater is incorporated into the a-priori information with WDM6 than with any of the other schemes. Major results show that convective rainfall regions are not well captured by the LIN and THOM schemes-based retrievals with correlations of 0.56 and 0.73. Rainfall distributions and their quantities retrieved from the WSM6 and WDM6 schemes-based estimations, however, show relatively better agreement with the PR observations with correlations of 0.79 and 0.81, respectively. Based on the comparisons of the various microphysics schemes in the retrievals, it appears that differences in the a-priori databases considerably affect the properties of rainfall estimations. This study also includes the discrepancy of estimated rain rate from passive radiometer and active radar for two rainfall systems of different cloud microphysics near the Yellow Sea. The first case have high cloud top (HCT) with large ice

  8. Non-contact determination of parasympathetic activation induced by a full stomach using microwave radar.

    PubMed

    Gotoh, Shinji; Suzuki, Satoshi; Imuta, Hayato; Kagawa, Masayuki; Badarch, Zorig; Matsui, Takemi

    2009-09-01

    In order to evaluate parasympathetic activation which causes driving errors, without placing any burden on the monitored individuals, we conducted a non-contact parasympathetic activation monitoring through the back of a chair using a compact 24-GHz microwave-radar. We measured the high-frequency (HF, 0.15-0.4 Hz) power spectrum of heart rate variability (HRV) which reflects parasympathetic activation, induced by a full stomach. All participants had a large all-you-can-eat meal with beverages for lunch within 20 min. Before and after the large meals for durations of 10 min, the non-contact measurement was conducted for seven healthy male volunteers (mean age: 23 +/- 1-year-old). In both non-contact (microwave radar) and contact (ECG as a reference) measurement, HF shows similar variations before and after large meal. Large meal significantly (p < 0.05) increased non-contact-derived HF from 1,026 +/- 510 to 1,893 +/- 613 ms(2) (922 +/- 628 to 1,861 +/- 940 ms(2), p < 0.05). This technique allows parasympathetic activation monitoring for safety precautions. PMID:19579041

  9. Soil Moisture Retrieval from Active/Passive Microwave Observation Synergy Using a Neural Network Approach

    NASA Astrophysics Data System (ADS)

    Kolassa, J.; Gentine, P.; Aires, F.; Prigent, C.

    2014-12-01

    In November 2014 NASA will launch the Soil Moisture Active/Passive (SMAP) mission carrying an L-band radiometer and radar sensor to observe surface soil moisture globally. This new type of instrument requires the development of innovative retrieval algorithms that are able to account for the different surface contributions to the satellite signal and at the same time can optimally exploit the synergy of active and passive microwave data. In this study, a neural network (NN) based retrieval algorithm has been developed using the example of active microwave observations from ASCAT and passive microwave observations from AMSR-E. In a first step, different preprocessing techniques, aiming to highlight the various contributions to the satellite signal, have been investigated. It was found that in particular for the passive microwave observations, the use of multiple frequencies and preprocessing steps could help the retrieval to disentangle the effects of soil moisture, vegetation and surface temperature. A spectral analysis investigated the temporal patterns in the satellite observations and thus assessed which soil moisture temporal variations could realistically be retrieved. The preprocessed data was then used in a NN based retrieval to estimate daily volumetric surface soil moisture at the global scale for the period 2002-2013. It could be shown that the synergy of data from the two sensors yielded a significant improvement of the retrieval performance demonstrating the benefit of multi-sensor approaches as proposed for SMAP. A comparison with a more traditional retrieval product merging approach furthermore showed that the NN technique is better able to exploit the complementarity of information provided by active and passive sensors. The soil moisture retrieval product was evaluated in the spatial, temporal and frequency domain against retrieved soil moisture from WACMOS and SMOS, modeled fields from ERA-interim/Land and in situ observations from the

  10. Active Microwave Pulse Compressor Using an Electron-Beam Triggered Switch

    NASA Astrophysics Data System (ADS)

    Ivanov, O. A.; Lobaev, M. A.; Vikharev, A. L.; Gorbachev, A. M.; Isaev, V. A.; Hirshfield, J. L.; Gold, S. H.; Kinkead, A. K.

    2013-03-01

    A high-power active microwave pulse compressor is described that operates by modulating the quality factor of an energy storage cavity by means of mode conversion controlled by a triggered electron-beam discharge across a switch cavity. This Letter describes the principle of operation, the design of the switch cavity, the configuration used for the tests, and the experimental results. The pulse compressor produced output pulses with 140-165 MW peak power, record peak power gains of 16∶1-20∶1, and FWHM pulse duration of 16-20 ns at a frequency of 11.43 GHz.

  11. Active microwave pulse compressor using an electron-beam triggered switch.

    PubMed

    Ivanov, O A; Lobaev, M A; Vikharev, A L; Gorbachev, A M; Isaev, V A; Hirshfield, J L; Gold, S H; Kinkead, A K

    2013-03-15

    A high-power active microwave pulse compressor is described that operates by modulating the quality factor of an energy storage cavity by means of mode conversion controlled by a triggered electron-beam discharge across a switch cavity. This Letter describes the principle of operation, the design of the switch cavity, the configuration used for the tests, and the experimental results. The pulse compressor produced output pulses with 140-165 MW peak power, record peak power gains of 16∶1-20∶1, and FWHM pulse duration of 16-20 ns at a frequency of 11.43 GHz. PMID:25166547

  12. Remote sensing for active volcano monitoring in Barren Island, India

    SciTech Connect

    Bhattacharya, A.; Reddy, C.S.S.; Srivastav, S.K. )

    1993-08-01

    The Barren Island Volcano, situated in the Andaman Sea of the Bay of Bengal, erupted recently (March, 1991) after a prolonged period of quiescence of about 188 years. This resumed activity coincides with similar outbreaks in the Philippines and Japan, which are located in an identical tectonic environment. This study addresses (1) remote sensing temporal monitoring of the volcanic activity, (2) detecting hot lava and measuring its pixel-integrated and subpixel temperatures, and (3) the importance of SWIR bands for high temperature volcanic feature detection. Seven sets of TM data acquired continuously from 3 March 1991 to 8 July 1991 have been analyzed. It is concluded that detectable pre-eruption warming took place around 25 March 1991 and volcanic activity started on 1 April 1991. It is observed that high temperature features, such as an erupting volcano, can register emitted thermal radiance in SWIR bands. Calculation of pixel-integrated and sub-pixel temperatures related to volcanic vents has been made, using the dual-band method. 6 refs.

  13. Active sensing in the categorization of visual patterns

    PubMed Central

    Yang, Scott Cheng-Hsin; Lengyel, Máté; Wolpert, Daniel M

    2016-01-01

    Interpreting visual scenes typically requires us to accumulate information from multiple locations in a scene. Using a novel gaze-contingent paradigm in a visual categorization task, we show that participants' scan paths follow an active sensing strategy that incorporates information already acquired about the scene and knowledge of the statistical structure of patterns. Intriguingly, categorization performance was markedly improved when locations were revealed to participants by an optimal Bayesian active sensor algorithm. By using a combination of a Bayesian ideal observer and the active sensor algorithm, we estimate that a major portion of this apparent suboptimality of fixation locations arises from prior biases, perceptual noise and inaccuracies in eye movements, and the central process of selecting fixation locations is around 70% efficient in our task. Our results suggest that participants select eye movements with the goal of maximizing information about abstract categories that require the integration of information from multiple locations. DOI: http://dx.doi.org/10.7554/eLife.12215.001 PMID:26880546

  14. Ultra-fast selective sensing of ethanol and petrol using microwave-range metamaterial complementary split-ring resonators

    NASA Astrophysics Data System (ADS)

    Rawat, Vaishali; Dhobale, Sandip; Kale, S. N.

    2014-10-01

    An extremely compact metamaterial microstrip sensor based on complementary split-ring-resonators (CSRRs) has been fabricated for chemical sensing. This device exhibits a resonance with high rejection at 4.5 GHz, which demonstrates concomitant variations when exposed to liquids of various permittivity values. The resonance frequency of CSRR is sensitive to the change in nearby dielectric material. The sensing of petrol shows a shift in frequency with a sharp dip in transmission, while, with ethanol, the frequency shift is accompanied with increase in the power of the signal. The ultra-fast reversibility and repeatability offers good headway towards hybrid fuel sensing applications.

  15. Quorum Sensing Inhibiting Activity of Streptomyces coelicoflavus Isolated from Soil.

    PubMed

    Hassan, Ramadan; Shaaban, Mona I; Abdel Bar, Fatma M; El-Mahdy, Areej M; Shokralla, Shadi

    2016-01-01

    Quorum sensing (QS) systems communicate bacterial population and stimulate microbial pathogenesis through signaling molecules. Inhibition of QS signals potentially suppresses microbial infections. Antimicrobial properties of Streptomyces have been extensively studied, however, less is known about quorum sensing inhibitory (QSI) activities of Streptomyces. This study explored the QSI potential of Streptomyces isolated from soil. Sixty-five bacterial isolates were purified from soil samples with morphological characteristics of Streptomyces. The three isolates: S6, S12, and S17, exhibited QSI effect by screening with the reporter, Chromobacterium violaceum. Isolate S17 was identified as Streptomyces coelicoflavus by sequencing of the hypervariable regions (V1-V6) of 16S rRNA and was assigned gene bank number KJ855087. The QSI effect of the cell-free supernatant of isolate S17 was not abolished by proteinase K indicating the non-enzymatic activity of QSI components of S17. Three major compounds were isolated and identified, using spectroscopic techniques (1D, 2D NMR, and Mass spectrometry), as behenic acid (docosanoic acid), borrelidin, and 1H-pyrrole-2-carboxylic acid. 1H-pyrrole-2-carboxylic acid inhibited QS and related virulence factors of Pseudomonas aeruginosa PAO1 including; elastase, protease, and pyocyanin without affecting Pseudomonas viability. At the molecular level, 1H-pyrrole-2-carboxylic acid suppressed the expression of QS genes (lasI, lasR, lasA, lasB, rhlI, rhlR, pqsA, and pqsR). Moreover, QSI activity of S17 was assessed under different growth conditions and ISP2 medium supplemented with glucose 0.4% w/v and adjusted at pH 7, showed the highest QSI action. In conclusion, 1H-pyrrole-2-carboxylic acid, one of the major metabolites of Streptomyces isolate S17, inhibited QS and virulence determinants of P. aeruginosa PAO1. The findings of the study open the scope to exploit the in vivo efficacy of this active molecule as anti-pathogenic and anti

  16. Quorum Sensing Inhibiting Activity of Streptomyces coelicoflavus Isolated from Soil

    PubMed Central

    Hassan, Ramadan; Shaaban, Mona I.; Abdel Bar, Fatma M.; El-Mahdy, Areej M.; Shokralla, Shadi

    2016-01-01

    Quorum sensing (QS) systems communicate bacterial population and stimulate microbial pathogenesis through signaling molecules. Inhibition of QS signals potentially suppresses microbial infections. Antimicrobial properties of Streptomyces have been extensively studied, however, less is known about quorum sensing inhibitory (QSI) activities of Streptomyces. This study explored the QSI potential of Streptomyces isolated from soil. Sixty-five bacterial isolates were purified from soil samples with morphological characteristics of Streptomyces. The three isolates: S6, S12, and S17, exhibited QSI effect by screening with the reporter, Chromobacterium violaceum. Isolate S17 was identified as Streptomyces coelicoflavus by sequencing of the hypervariable regions (V1–V6) of 16S rRNA and was assigned gene bank number KJ855087. The QSI effect of the cell-free supernatant of isolate S17 was not abolished by proteinase K indicating the non-enzymatic activity of QSI components of S17. Three major compounds were isolated and identified, using spectroscopic techniques (1D, 2D NMR, and Mass spectrometry), as behenic acid (docosanoic acid), borrelidin, and 1H-pyrrole-2-carboxylic acid. 1H-pyrrole-2-carboxylic acid inhibited QS and related virulence factors of Pseudomonas aeruginosa PAO1 including; elastase, protease, and pyocyanin without affecting Pseudomonas viability. At the molecular level, 1H-pyrrole-2-carboxylic acid suppressed the expression of QS genes (lasI, lasR, lasA, lasB, rhlI, rhlR, pqsA, and pqsR). Moreover, QSI activity of S17 was assessed under different growth conditions and ISP2 medium supplemented with glucose 0.4% w/v and adjusted at pH 7, showed the highest QSI action. In conclusion, 1H-pyrrole-2-carboxylic acid, one of the major metabolites of Streptomyces isolate S17, inhibited QS and virulence determinants of P. aeruginosa PAO1. The findings of the study open the scope to exploit the in vivo efficacy of this active molecule as anti-pathogenic and anti

  17. Active self-sensing scheme development for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Lee, Sang Jun; Sohn, Hoon

    2006-12-01

    Smart materials such as lead zirconate titanate (PZT) have been widely used for generating and measuring guided waves in solid media. The guided waves are then used to detect local defects for structural health monitoring (SHM) applications. In this study, a self-sensing system, composed of self-sensing algorithms and a self-sensing circuit equivalent to a charge amplifier, is developed so that a single PZT wafer can be used for simultaneous actuation and sensing. First, a PZT wafer is modeled as a single capacitor and a voltage source, and a so-called scaling factor, defined as the ratio of the PZT capacitance to the capacitance of the feedback capacitor in the self-sensing circuit, is estimated by applying known waveforms to the PZT wafer. Then, the mechanical response of the PZT wafer coupled with the host structure's response is extracted from the measured PZT output voltage when an arbitrary excitation is applied to the same PZT wafer. While existing self-sensing techniques focus on vibration controls, the proposed self-sensing scheme attempts to improve the accuracy of extracted sensing signals in the time domain. The simplicity, adaptability and autonomous nature of the proposed self-sensing scheme make it attractive for continuous monitoring of structures in the field. The effectiveness of the proposed self-sensing scheme is investigated through numerical simulations and experiments on a cantilever beam.

  18. High accuracy laboratory spectroscopy to support active greenhouse gas sensing

    NASA Astrophysics Data System (ADS)

    Long, D. A.; Bielska, K.; Cygan, A.; Havey, D. K.; Okumura, M.; Miller, C. E.; Lisak, D.; Hodges, J. T.

    2011-12-01

    Recent carbon dioxide (CO2) remote sensing missions have set precision targets as demanding as 0.25% (1 ppm) in order to elucidate carbon sources and sinks [1]. These ambitious measurement targets will require the most precise body of spectroscopic reference data ever assembled. Active sensing missions will be especially susceptible to subtle line shape effects as the narrow bandwidth of these measurements will greatly limit the number of spectral transitions which are employed in retrievals. In order to assist these remote sensing missions we have employed frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) [2], a high-resolution, ultrasensitive laboratory technique, to measure precise line shape parameters for transitions of O2, CO2, and other atmospherically-relevant species within the near-infrared. These measurements have led to new HITRAN-style line lists for both 16O2 [3] and rare isotopologue [4] transitions in the A-band. In addition, we have performed detailed line shape studies of CO2 transitions near 1.6 μm under a variety of broadening conditions [5]. We will address recent measurements in these bands as well as highlight recent instrumental improvements to the FS-CRDS spectrometer. These improvements include the use of the Pound-Drever-Hall locking scheme, a high bandwidth servo which enables measurements to be made at rates greater than 10 kHz [6]. In addition, an optical frequency comb will be utilized as a frequency reference, which should allow for transition frequencies to be measured with uncertainties below 10 kHz (3×10-7 cm-1). [1] C. E. Miller, D. Crisp, P. L. DeCola, S. C. Olsen, et al., J. Geophys. Res.-Atmos. 112, D10314 (2007). [2] J. T. Hodges, H. P. Layer, W. W. Miller, G. E. Scace, Rev. Sci. Instrum. 75, 849-863 (2004). [3] D. A. Long, D. K. Havey, M. Okumura, C. E. Miller, et al., J. Quant. Spectrosc. Radiat. Transfer 111, 2021-2036 (2010). [4] D. A. Long, D. K. Havey, S. S. Yu, M. Okumura, et al., J. Quant. Spectrosc

  19. Remote sensor response study in the regime of the microwave radiation-induced magnetoresistance oscillations

    SciTech Connect

    Ye, Tianyu; Mani, R. G.; Wegscheider, W.

    2013-11-04

    A concurrent remote sensing and magneto-transport study of the microwave excited two dimensional electron system (2DES) at liquid helium temperatures has been carried out using a carbon detector to remotely sense the microwave activity of the 2D electron system in the GaAs/AlGaAs heterostructure during conventional magneto-transport measurements. Various correlations are observed and reported between the oscillatory magnetotransport and the remotely sensed reflection. In addition, the oscillatory remotely sensed signal is shown to exhibit a power law type variation in its amplitude, similar to the radiation-induced magnetoresistance oscillations.

  20. Synthesis of PbMoO4 nanoparticles by microwave-assisted hydrothermal process and their photocatalytic activity.

    PubMed

    Song, Young In; Lim, Kwon Taek; Lee, Gun Dae; Lee, Man Sig; Hong, Seong-Soo

    2014-11-01

    Lead molybdate (PbMoO4) was successfully synthesized using a microwave-assisted method and characterized by XRD, Raman spectroscopy, SEM, PL and DRS. We also investigated the photocatalytic activity of these materials for the decomposition of Rhodamin B under UV-light irradiation. The XRD and Raman results revealed the successful synthesis of 42-52 nm, well-crystallized PbMoO4 crystals with the microwave-assisted hydrothermal method. The PbMoO4 catalysts prepared using the microwave-assisted process enhanced the photocatalytic activity compared to that prepared by hydrothermal method and the catalysts prepared at a solution pH = 11 and temperature of 105 degrees C showed the highest photocatalytic activity. The PL peaks appeared at about 540 nm for all catalysts and the excitonic PL signal was proportional to the photocatalytic activity for the decomposition of Rhodamin B. PMID:25958553

  1. Short term prediction of dynamic hydra precipitation activity using a microwave radiometer over Eastern Himalaya, India

    NASA Astrophysics Data System (ADS)

    Singh, S.

    2015-12-01

    First ever study of the feasibility of ground based radiometric study to predict a very short term based rain precipitation study has been conducted in eastern Himalaya, Darjeeling (27.01°N, 88.15°E, 2200 masl). Short term prediction or nowcasting relates to forecasting convective precipitation for time periods less than a few hours to avoid its effect on agriculture, aviation and lifestyle. Theoretical models involving radiometric predictions are not well understood and lack in temporal and spatial resolution. In this study specific utilization of a microwave Radiometer (Radiometrics Corporation, USA) for online monitoring of precipitable rainfall activity has been observed repeatability of data has been established. Previous few studies have shown the increase of water vapour and corresponding Brightness Temperature, but in mountain climatic conditions over Darjeeling, due to presence of fog 90 % of the year, water vapour monitoring related predictions can lead to false alarms. The measurement of blackbody emission noise in the bands of 23.8 GHz and 31.4 GHz, using a quadratic regression retrieval algorithm is converted to atmospheric parameters like integrated water vapour and liquid water content. It has been found in our study that the liquid water shows significant activity prior to precipitation events even for mild and stratiform rainfall. The alarm can be generated well 20 mins before the commencement of actual rain events even in the upper atmosphere of 6 Kms, measured by a rain radar also operating in 24 Ghz microwave band. Although few rain events were found and reported which do not respond in the microwave liquid water channel. Efforts to identify such rain events and their possible explanation is going on and shall be reported in near future. Such studies are important to predict flash flooding in the Himalayas. Darjeeling owing to its geographical conditions experiences mild to very heavy rain. Such studies help improve aspects of Himalayas as

  2. Statistical Analysis of the Correlation between Microwave Emission Anomalies and Seismic Activity Based on AMSR-E Satellite Data

    NASA Astrophysics Data System (ADS)

    qin, kai; Wu, Lixin; De Santis, Angelo; Zhang, Bin

    2016-04-01

    Pre-seismic thermal IR anomalies and ionosphere disturbances have been widely reported by using the Earth observation system (EOS). To investigate the possible physical mechanisms, a series of detecting experiments on rock loaded to fracturing were conducted. Some experiments studies have demonstrated that microwave radiation energy will increase under the loaded rock in specific frequency and the feature of radiation property can reflect the deformation process of rock fracture. This experimental result indicates the possibility that microwaves are emitted before earthquakes. Such microwaves signals are recently found to be detectable before some earthquake cases from the brightness temperature data obtained by the microwave-radiometer Advanced Microwave-Scanning Radiometer for the EOS (AMSR-E) aboard the satellite Aqua. This suggested that AMSR-E with vertical- and horizontal-polarization capability for six frequency bands (6.925, 10.65, 18.7, 23.8, 36.5, and 89.0 GHz) would be feasible to detect an earthquake which is associated with rock crash or plate slip. However, the statistical analysis of the correlation between satellite-observed microwave emission anomalies and seismic activity are firstly required. Here, we focus on the Kamchatka peninsula to carry out a statistical study, considering its high seismicity activity and the dense orbits covering of AMSR-E in high latitudes. 8-years (2003-2010) AMSR-E microwave brightness temperature data were used to reveal the spatio-temporal association between microwave emission anomalies and 17 earthquake events (M>5). Firstly, obvious spatial difference of microwave brightness temperatures between the seismic zone at the eastern side and the non-seismic zone the western side within the Kamchatka peninsula are found. Secondly, using both vertical- and horizontal-polarization to extract the temporal association, it is found that abnormal changes of microwave brightness temperatures appear generally 2 months before the

  3. Temporal Signatures of Taste Quality Driven by Active Sensing

    PubMed Central

    Sun, Chengsan; Hill, David L.

    2014-01-01

    Animals actively acquire sensory information from the outside world, with rodents sniffing to smell and whisking to feel. Licking, a rapid motor sequence used for gustation, serves as the primary means of controlling stimulus access to taste receptors in the mouth. Using a novel taste-quality discrimination task in head-restrained mice, we measured and compared reaction times to four basic taste qualities (salt, sour, sweet, and bitter) and found that certain taste qualities are perceived inherently faster than others, driven by the precise biomechanics of licking and functional organization of the peripheral gustatory system. The minimum time required for accurate perception was strongly dependent on taste quality, ranging from the sensory-motor limits of a single lick (salt, ∼100 ms) to several sampling cycles (bitter, >500 ms). Further, disruption of sensory input from the anterior tongue significantly impaired the speed of perception of some taste qualities, with little effect on others. Overall, our results show that active sensing may play an important role in shaping the timing of taste-quality representations and perception in the gustatory system. PMID:24872546

  4. Degradation of Active Brilliant Red X-3B by a microwave discharge electrodeless lamp in the presence of activated carbon.

    PubMed

    Fu, Jie; Wen, Teng; Wang, Qing; Zhang, Xue-Wei; Zeng, Qing-Fu; An, Shu-Qing; Zhu, Hai-Liang

    2010-06-01

    Degradation of Active Brilliant Red X-3B (X-3B) in aqueous solution by a microwave discharge electrodeless lamp (MDEL) in the presence of activated carbon was investigated. The preliminary results proved this method could effectively degrade X-3B in aqueous solution. The removal percentages of colour and chemical oxygen demand were up to approximately 99% and 66%, respectively, at the conditions of 0.8 g/L dye concentration, 20 g/L activated carbon, pH 7.0 and 8 min microwave irradiation time. The degradation basically belonged to first-order reaction kinetics and its rate constant was 0.42 min(-1). No aromatic organics were detected in the final treated solution, indicating that the mineralization was relatively complete. By studying the change in solution properties, it could be concluded that MDEL-assisted oxidation was the dominant reaction mechanism. In addition, the influence of operational parameters and reuse of activated carbon were also discussed. PMID:20586239

  5. Spanish activities (research and industrial applications) in the field of microwave material treatment

    SciTech Connect

    Catala Civera, J.M.; Reyes Davo, E.R. de los

    1996-12-31

    The GCM (Microwave Heating Group) within the Communications Department at the Technical University of Valencia is dedicated to the study of microwaves and their use in the current industrial processes in the Valencian Community and in Spain. To this end, a microwave heating laboratory has been developed and the benefits of incorporating microwave technologies into current industrial processes have been demonstrated. In this paper some of the industrial applications which are being investigated are presented.

  6. Efficient Catalytic Activity BiFeO3 Nanoparticles Prepared by Novel Microwave-Assisted Synthesis.

    PubMed

    Zou, Jing; Gong, Wanyun; Ma, Jinai; Li, Lu; Jiang, Jizhou

    2015-02-01

    A novel microwave-assisted sol-gel method was applied to the synthesis of the single-phase perovskite bismuth ferrite nanoparticles (BFO NPs) with the mean diameter ca. 73.7 nm. The morphology was characterized by scanning electron microscope (SEM). The X-ray diffraction (XRD) revealed the rhombohedral phase with R3c space group. The weak ferromagnetic behavior at room temperature was affirmed by the vibrating sample magnetometer (VSM). According to the UV-vis diffuse reflectance spectrum (UV-DSR), the band gap energy of BFO NPs was determined to be 2.18 eV. The electrochemical activity was evaluated by BFO NPs-chitosan-glassy carbon electrode (BFO-CS-GCE) sensor for detection of p-nitrophenol contaminants. The material showed an efficient oxidation catalytic activity by degrading methylene blue (MB). It was found that the degradation efficiency of 10 mg L-1 MB at pH 6.0 was above 90.9% after ultrasound- and microwave-combined-assisted (US-MW) irradiation for 15 min with BFO NPs as catalyst and H202 as oxidant. A possible reaction mechanism of degradation of MB was also proposed. PMID:26353647

  7. Low-level microwave irradiation and central cholinergic activity: a dose-response study

    SciTech Connect

    Lai, H.; Carino, M.A.; Horita, A.; Guy, A.W.

    1989-01-01

    Rats were irradiated with circularly polarized, 2,450-MHz pulsed microwaves (2-microseconds pulses, 500 pulses per second (pps)) for 45 min in the cylindrical waveguide system of Guy et al. Immediately after exposure, sodium-dependent high-affinity choline uptake, an indicator of cholinergic activity in neural tissue, was measured in the striatum, frontal cortex, hippocampus, and hypothalamus. The power density was set to give average whole-body specific absorption rates (SAR) of 0.3, 0.45, 0.6, 0.75, 0.9, or 1.2 W/kg to study the dose-response relationship between the rate of microwave energy absorption and cholinergic activity in the different areas of the brain. Decrease in choline uptake was observed in the striatum at a SAR of 0.75 W/kg and above, whereas for the frontal cortex and hippocampus, decreases in choline uptake were observed at a SAR of 0.45 W/kg and above. No significant effect was observed in the hypothalamus at the irradiation power densities studied. The probit analysis was used to determine the SAR50 in each brain area, i.e., the SAR at which 50% of maximum response was elicited. SAR50 values for the striatum, frontal cortex, and hippocampus were 0.65, 0.38, and 0.44 W/kg, respectively.

  8. Diurnal variations of stratospheric ozone measured by ground-based microwave remote sensing at the Mauna Loa NDACC site: measurement validation and GEOSCCM model comparison

    NASA Astrophysics Data System (ADS)

    Parrish, A.; Boyd, I. S.; Nedoluha, G. E.; Bhartia, P. K.; Frith, S. M.; Kramarova, N. A.; Connor, B. J.; Bodeker, G. E.; Froidevaux, L.; Shiotani, M.; Sakazaki, T.

    2014-07-01

    There is presently renewed interest in diurnal variations of stratospheric and mesospheric ozone for the purpose of supporting homogenization of records of various ozone measurements that are limited by the technique employed to being made at certain times of day. We have made such measurements for 19 years using a passive microwave remote sensing technique at the Mauna Loa Observatory (MLO) in Hawaii, which is a primary station in the Network for Detection of Atmospheric Composition Change (NDACC). We have recently reprocessed these data with hourly time resolution to study diurnal variations. We inspected differences between pairs of the ozone spectra (e.g., day and night) from which the ozone profiles are derived to determine the extent to which they may be contaminated by diurnally varying systematic instrumental or measurement effects. These are small, and we have reduced them further by selecting data that meet certain criteria that we established. We have calculated differences between profiles measured at different times: morning-night, afternoon-night, and morning-afternoon and have intercompared these with like profiles derived from the Aura Microwave Limb Sounder (Aura-MLS), the Upper Atmosphere Research Satellite Microwave Limb Sounder (UARS-MLS), the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES), and Solar Backscatter Ultraviolet version 2 (SBUV/2) measurements. Differences between averages of coincident profiles are typically < 1.5% of typical nighttime values over most of the covered altitude range with some exceptions. We calculated averages of ozone values for each hour from the Mauna Loa microwave data, and normalized these to the average for the first hour after midnight for comparison with corresponding values calculated with the Goddard Earth Observing System Chemistry Climate Model (GEOSCCM). We found that the measurements and model output mostly agree to better than 1.5% of the midnight value, with one noteworthy exception

  9. Hydrological Application of Remote Sensing: Surface States -- Snow

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K.; Kelly, Richard E. J.; Foster, James L.; Chang, Alfred T. C.

    2004-01-01

    Remote sensing research of snow cover has been accomplished for nearly 40 years. The use of visible, near-infrared, active and passive-microwave remote sensing for the analysis of snow cover is reviewed with an emphasis on the work on the last decade.

  10. Predicting eruptions from precursory activity using remote sensing data hybridization

    NASA Astrophysics Data System (ADS)

    Reath, K. A.; Ramsey, M. S.; Dehn, J.; Webley, P. W.

    2016-07-01

    Many volcanoes produce some level of precursory activity prior to an eruption. This activity may or may not be detected depending on the available monitoring technology. In certain cases, precursors such as thermal output can be interpreted to make forecasts about the time and magnitude of the impending eruption. Kamchatka (Russia) provides an ideal natural laboratory to study a wide variety of eruption styles and precursory activity prior to an eruption. At Bezymianny volcano for example, a clear increase in thermal activity commonly occurs before an eruption, which has allowed predictions to be made months ahead of time. Conversely, the eruption of Tolbachik volcano in 2012 produced no discernable thermal precursors before the large scale effusive eruption. However, most volcanoes fall between the extremes of consistently behaved and completely undetectable, which is the case with neighboring Kliuchevskoi volcano. This study tests the effectiveness of using thermal infrared (TIR) remote sensing to track volcanic thermal precursors using data from both the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Advanced Very High Resolution Radiometer (AVHRR) sensors. It focuses on three large eruptions that produced different levels and durations of effusive and explosive behavior at Kliuchevskoi. Before each of these eruptions, TIR spaceborne sensors detected thermal anomalies (i.e., pixels with brightness temperatures > 2 °C above the background temperature). High-temporal, low-spatial resolution (i.e., ~ hours and 1 km) AVHRR data are ideal for detecting large thermal events occurring over shorter time scales, such as the hot material ejected following strombolian eruptions. In contrast, high-spatial, low-temporal resolution (i.e., days to weeks and 90 m) ASTER data enables the detection of much lower thermal activity; however, activity with a shorter duration will commonly be missed. ASTER and AVHRR data are combined to track low

  11. Specific quorum sensing-disrupting activity (A QSI) of thiophenones and their therapeutic potential.

    PubMed

    Yang, Qian; Scheie, Anne Aamdal; Benneche, Tore; Defoirdt, Tom

    2015-01-01

    Disease caused by antibiotic resistant pathogens is becoming a serious problem, both in human and veterinary medicine. The inhibition of quorum sensing, bacterial cell-to-cell communication, is a promising alternative strategy to control disease. In this study, we determined the quorum sensing-disrupting activity of 20 thiophenones towards the quorum sensing model bacterium V. harveyi. In order to exclude false positives, we propose a new parameter (AQSI) to describe specific quorum sensing activity. AQSI is defined as the ratio between inhibition of quorum sensing-regulated activity in a reporter strain and inhibition of the same activity when it is independent of quorum sensing. Calculation of AQSI allowed to exclude five false positives, whereas the six most active thiophenones (TF203, TF307, TF319, TF339, TF342 and TF403) inhibited quorum sensing at 0.25 μM, with AQSI higher than 10. Further, we determined the protective effect and toxicity of the thiophenones in a highly controlled gnotobiotic model system with brine shrimp larvae. There was a strong positive correlation between the specific quorum sensing-disrupting activity of the thiophenones and the protection of brine shrimp larvae against pathogenic V. harveyi. Four of the most active quorum sensing-disrupting thiophenones (TF 203, TF319, TF339 and TF342) were considered to be promising since they have a therapeutic potential of at least 10. PMID:26647822

  12. Specific quorum sensing-disrupting activity (AQSI) of thiophenones and their therapeutic potential

    PubMed Central

    Yang, Qian; Aamdal Scheie, Anne; Benneche, Tore; Defoirdt, Tom

    2015-01-01

    Disease caused by antibiotic resistant pathogens is becoming a serious problem, both in human and veterinary medicine. The inhibition of quorum sensing, bacterial cell-to-cell communication, is a promising alternative strategy to control disease. In this study, we determined the quorum sensing-disrupting activity of 20 thiophenones towards the quorum sensing model bacterium V. harveyi. In order to exclude false positives, we propose a new parameter (AQSI) to describe specific quorum sensing activity. AQSI is defined as the ratio between inhibition of quorum sensing-regulated activity in a reporter strain and inhibition of the same activity when it is independent of quorum sensing. Calculation of AQSI allowed to exclude five false positives, whereas the six most active thiophenones (TF203, TF307, TF319, TF339, TF342 and TF403) inhibited quorum sensing at 0.25 μM, with AQSI higher than 10. Further, we determined the protective effect and toxicity of the thiophenones in a highly controlled gnotobiotic model system with brine shrimp larvae. There was a strong positive correlation between the specific quorum sensing-disrupting activity of the thiophenones and the protection of brine shrimp larvae against pathogenic V. harveyi. Four of the most active quorum sensing-disrupting thiophenones (TF 203, TF319, TF339 and TF342) were considered to be promising since they have a therapeutic potential of at least 10. PMID:26647822

  13. Earth Observing System/Advanced Microwave SoundingUnit-A (EOS/AMSU-A): Acquisition activities plan

    NASA Technical Reports Server (NTRS)

    Schwantje, Robert

    1994-01-01

    This is the acquisition activities plan for the software to be used in the Earth Observing System (EOS) Advanced Microwave Sounding Unit-A (AMSU-A) system. This document is submitted in response to Contract NAS5-323 14 as CDRL 508. The procurement activities required to acquire software for the EOS/AMSU-A program are defined.

  14. Investigation of temporal-spatial parameters of an urban heat island on the basis of passive microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Khaikine, M. N.; Kuznetsova, I. N.; Kadygrov, E. N.; Miller, E. A.

    2006-02-01

    Quantitative measurements of the impact of an urban environment on the thermal state of the atmospheric boundary layer are presented. Temperature profiles up to the height of 600 m were obtained in a continuous series of measurements by three microwave profilers MTP-5 located in different areas of Moscow. The influence of this large city on urban heat island (UHI) parameters was estimated on occasions with stationary atmospheric processes and during cases with frontal passage. Two types of UHI were identified: one with a dome of urban warmth at all levels, and another with a low warm dome in combination with a lens of cold air above.

  15. Realistic Instrumentation Platform for Active and Passive Optical Remote Sensing.

    PubMed

    Brydegaard, Mikkel; Merdasa, Aboma; Gebru, Alem; Jayaweera, Hiran; Svanberg, Sune

    2016-02-01

    We describe the development of a novel versatile optical platform for active and passive remote sensing of environmental parameters. Applications include assessment of vegetation status and water quality. The system is also adapted for ecological studies, such as identification of flying insects including agricultural pests. The system is based on two mid-size amateur astronomy telescopes, continuous-wave diode lasers at different wavelengths ranging from violet to the near infrared, and detector facilities including quadrant photodiodes, two-dimensional and line scan charge-coupled device cameras, and a compact digital spectrometer. Application examples include remote Ramanlaser-induced fluorescence monitoring of water quality at 120 m distance, and insect identification at kilometer ranges using the recorded wing beat frequency and its spectrum of overtones. Because of the low cost this developmental platform is very suitable for advanced research projects in developing countries and has, in fact, been multiplied during hands-on workshops and is now being used by a number of groups at African universities. PMID:26772187

  16. Active sensing via movement shapes spatiotemporal patterns of sensory feedback.

    PubMed

    Stamper, Sarah A; Roth, Eatai; Cowan, Noah J; Fortune, Eric S

    2012-05-01

    Previous work has shown that animals alter their locomotor behavior to increase sensing volumes. However, an animal's own movement also determines the spatial and temporal dynamics of sensory feedback. Because each sensory modality has unique spatiotemporal properties, movement has differential and potentially independent effects on each sensory system. Here we show that weakly electric fish dramatically adjust their locomotor behavior in relation to changes of modality-specific information in a task in which increasing sensory volume is irrelevant. We varied sensory information during a refuge-tracking task by changing illumination (vision) and conductivity (electroreception). The gain between refuge movement stimuli and fish tracking responses was functionally identical across all sensory conditions. However, there was a significant increase in the tracking error in the dark (no visual cues). This was a result of spontaneous whole-body oscillations (0.1 to 1 Hz) produced by the fish. These movements were costly: in the dark, fish swam over three times further when tracking and produced more net positive mechanical work. The magnitudes of these oscillations increased as electrosensory salience was degraded via increases in conductivity. In addition, tail bending (1.5 to 2.35 Hz), which has been reported to enhance electrosensory perception, occurred only during trials in the dark. These data show that both categories of movements - whole-body oscillations and tail bends - actively shape the spatiotemporal dynamics of electrosensory feedback. PMID:22496294

  17. An integrated active sensing system for damage identifcation and prognosis

    SciTech Connect

    Wait, J. R.; Park, G. H.; Sohn, H.; Farrar, C. R.

    2004-01-01

    This paper illustrates an integrated approach for identifying structural damage. Two damage identification techniques, Lamb wave propagation and impedance-based methods, are investigated utilizing piezoelectric (PZT) actuators/sensors. The Lamb wave propagation and the impedance methods operate in high frequency ranges (typically > 30 kHz) at which there are measurable changes in structural responses even for incipient damage such as small cracks, debonding, delamination, and loose connections. In Lamb wave propagation, one PZT is used to launch an elastic wave through the structure, and responses are measured by an array of sensors. The technique used for the Lamb wave propagation method looks for the possibility of damage by tracking changes in transmission velocity and wave attenuation/reflections. Experimental results show that this method works well for surface anomalies. The impedance method monitors the variations in structural mechanical impedance, which is coupled with the electrical impedance of the PZT. Through monitoring the measured electrical impedance and comparing it to a baseline measurement, a decision can be made about whether or not structural damage has occurred or is imminent. In addition, significant advances have been made recently by incorporating advanced statistic-based signal processing techniques into the impedance methods. To date, several sets of experiments have been conducted on a cantilevered aluminum plate and composite plate to demonstrate the feasibility of this combined active sensing technology.

  18. Active adjoint modeling method in microwave induced thermoacoustic tomography for breast tumor.

    PubMed

    Zhu, Xiaozhang; Zhao, Zhiqin; Wang, Jinguo; Chen, Guoping; Liu, Qing Huo

    2014-07-01

    To improve the model-based inversion performance of microwave induced thermoacoustic tomography for breast tumor imaging, an active adjoint modeling (AAM) method is proposed. It aims to provide a more realistic breast acoustic model used for tumor inversion as the background by actively measuring and reconstructing the structural heterogeneity of human breast environment. It utilizes the reciprocity of acoustic sensors, and adapts the adjoint tomography method from seismic exploration. With the reconstructed acoustic model of breast environment, the performance of model-based inversion method such as time reversal mirror is improved significantly both in contrast and accuracy. To prove the advantage of AAM, a checkerboard pattern model and anatomical realistic breast models have been used in full wave numerical simulations. PMID:24956614

  19. Microwave-assisted, one-pot syntheses and fungicidal activity of polyfluorinated 2-benzylthiobenzothiazoles.

    PubMed

    Huang, Wei; Yang, Guang-Fu

    2006-12-15

    Polyfluorinated 2-benzylthiobenzothiazoles 3a-l are prepared via a microwave-assisted, one-pot procedure. The advantages, such as good to excellent yields, shorter reaction time (14-21min), readily available starting material, and simple purification procedure, distinguish the present protocol from other existing methods used for the synthesis of 2-benzylthiobenzothiazoles. Bioassay indicated that most of the compounds showed significant fungicidal activity against Rhizoctonia solani, Botrytis cinereapers, and Dothiorella gregaria at a dosage of 50microg/mL. Interestingly, compared to the control of commercial fungicide, triadimefon, compound 3c exhibited much higher activities against R. solani, B. cinereapers, and D. gregaria, which showed that the polyfluorinated 2-benzylthiobenzothiazoles can be used as lead compound for developing novel fungicides. PMID:17008103

  20. Bioinspired active whisker sensor for robotic vibrissal tactile sensing

    NASA Astrophysics Data System (ADS)

    Ju, Feng; Ling, Shih-Fu

    2014-12-01

    A whisker transducer (WT) inspired by rat’s vibrissal tactile perception is proposed based on a transduction matrix model characterizing the electro-mechanical transduction process in both forward and backward directions. It is capable of acting as an actuator to sweep the whisker and simultaneously as a sensor to sense the force, motion, and mechanical impedance at whisker tip. Its validity is confirmed by numerical simulation using a finite element model. A prototype is then fabricated and its transduction matrix is determined by parameter identification. The calibrated WT can accurately sense mechanical impedance which is directly related to stiffness, mass and damping. Subsequent vibrissal tactile sensing of sandpaper texture reveals that the real part of mechanical impedance sensed by WT is correlated with sandpaper roughness. Texture discrimination is successfully achieved by inputting the real part to a k-means clustering algorithm. The mechanical impedance sensing ability as well as other features of the WT such as simultaneous-actuation-and-sensing makes it a good solution to robotic tactile sensing.

  1. Fe-, Co-, and Ni-Loaded Porous Activated Carbon Balls as Lightweight Microwave Absorbents.

    PubMed

    Li, Guomin; Wang, Liancheng; Li, Wanxi; Xu, Yao

    2015-11-16

    Porous activated carbon ball (PACB) composites impregnated with iron, cobalt, nickel and/or their oxides were synthesized through a wet chemistry method involving PACBs as the carrier to load Fe(3+), Co(2+), and Ni(2+) ions and a subsequent carbothermal reduction at different annealing temperatures. The results show that the pyrolysis products of nitrates and/or the products from the carbothermal reduction are embedded in the pores of the PACBs, with different distributions, resulting in different crystalline phases. The as-prepared PACB composites possessed high specific surface areas of 791.2-901.5 m(2)  g(-1) and low densities of 1.1-1.3 g cm(-3). Minimum reflection loss (RL) values of -50.1, -20.6, and -20.4 dB were achieved for Fe-PACB (annealed at 500 °C), Co-PACB (annealed at 800 °C), and Ni-PACB (annealed at 800 °C) composites, respectively. Moreover, the influence of the amount of the magnetic components in the PACB composites on the microwave-absorbing performances was investigated, further confirming that the dielectric loss was the primary contributor to microwave absorption. PMID:26373310

  2. Cellulose/CaCO3 nanocomposites: microwave ionic liquid synthesis, characterization, and biological activity.

    PubMed

    Ma, Ming-Guo; Dong, Yan-Yan; Fu, Lian-Hua; Li, Shu-Ming; Sun, Run-Cang

    2013-02-15

    The purposes of this article are to synthesize the biomass-based hybrid nanocomposites using green method in green solvent and evaluate its biological activity. In this paper, microwave-assisted ionic liquid method is applied to the preparation of cellulose/CaCO(3) hybrid nanocomposites in the alkali extraction cellulose using CaCl(2) and Na(2)CO(3) as starting reactants. The ionic liquid acts as the excellent solvent for absorbing microwave and the dissolution of cellulose, and the synthesis of cellulose/CaCO(3) nanocomposites. The influences of reaction parameters such as the cellulose concentration and the types of solvent on the products were investigated. The increasing cellulose concentration favored the growth of CaCO(3). The morphologies of CaCO(3) changed from polyhedral to cube to particle with increasing cellulose concentration. Moreover, the solvents had an effect on the shape and dispersion of CaCO(3). Cytotoxicity experiments demonstrated that the cellulose/CaCO(3) nanocomposites had good biocompatibility and could be a candidate for the biomedical applications. PMID:23399205

  3. Biopolymers Regulate Silver Nanoparticle under Microwave Irradiation for Effective Antibacterial and Antibiofilm Activities

    PubMed Central

    Velusamy, Palaniyandi; Su, Chia-Hung; Venkat Kumar, Govindarajan; Adhikary, Shritama; Pandian, Kannaiyan; Gopinath, Subash C. B.; Chen, Yeng; Anbu, Periasamy

    2016-01-01

    In the current study, facile synthesis of carboxymethyl cellulose (CMC) and sodium alginate capped silver nanoparticles (AgNPs) was examined using microwave radiation and aniline as a reducing agent. The biopolymer matrix embedded nanoparticles were synthesized under various experimental conditions using different concentrations of biopolymer (0.5, 1, 1.5, 2%), volumes of reducing agent (50, 100, 150 μL), and duration of heat treatment (30 s to 240 s). The synthesized nanoparticles were analyzed by scanning electron microscopy, UV-Vis spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy for identification of AgNPs synthesis, crystal nature, shape, size, and type of capping action. In addition, the significant antibacterial efficacy and antibiofilm activity of biopolymer capped AgNPs were demonstrated against different bacterial strains, Staphylococcus aureus MTCC 740 and Escherichia coli MTCC 9492. These results confirmed the potential for production of biopolymer capped AgNPs grown under microwave irradiation, which can be used for industrial and biomedical applications. PMID:27304672

  4. The killing activity of microwaves on some non-sporogenic and sporogenic medically important bacterial strains.

    PubMed

    Najdovski, L; Dragas, A Z; Kotnik, V

    1991-12-01

    The killing activity of microwaves of 2450 MHz frequency and 325 W, 650 W and 1400 W power on some bacterial strains was investigated. Vegetative strains of Staphylococcus aureus, Streptococcus pyogenes Group A, Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis and spores of Bacillus subtilis and Bacillis stearothermophilus in aqueous suspensions were exposed to 325 W and 650 W waves for different lengths of time. Enterococcus faecalis and spores of B. subtilis and B. stearothermophilus were exposed additionally to 1400 W waves in aqueous and 'dried' suspensions. Vegetative bacteria were promptly killed in 5 min or less, E. faecalis being slightly more resistant. Bacterial spores were only killed in aqueous suspension when a 1400 W setting was used for 10 to 20 min. Bacterial spores adhering to the tube walls after the aqueous suspension was poured out were reduced in number. We assume that the conventional microwave ovens available on the market may be used for a high level of disinfection but not for sterilization, and only then if sufficient water is present. PMID:1686036

  5. Biopolymers Regulate Silver Nanoparticle under Microwave Irradiation for Effective Antibacterial and Antibiofilm Activities.

    PubMed

    Velusamy, Palaniyandi; Su, Chia-Hung; Venkat Kumar, Govindarajan; Adhikary, Shritama; Pandian, Kannaiyan; Gopinath, Subash C B; Chen, Yeng; Anbu, Periasamy

    2016-01-01

    In the current study, facile synthesis of carboxymethyl cellulose (CMC) and sodium alginate capped silver nanoparticles (AgNPs) was examined using microwave radiation and aniline as a reducing agent. The biopolymer matrix embedded nanoparticles were synthesized under various experimental conditions using different concentrations of biopolymer (0.5, 1, 1.5, 2%), volumes of reducing agent (50, 100, 150 μL), and duration of heat treatment (30 s to 240 s). The synthesized nanoparticles were analyzed by scanning electron microscopy, UV-Vis spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy for identification of AgNPs synthesis, crystal nature, shape, size, and type of capping action. In addition, the significant antibacterial efficacy and antibiofilm activity of biopolymer capped AgNPs were demonstrated against different bacterial strains, Staphylococcus aureus MTCC 740 and Escherichia coli MTCC 9492. These results confirmed the potential for production of biopolymer capped AgNPs grown under microwave irradiation, which can be used for industrial and biomedical applications. PMID:27304672

  6. Effects of microwave irradiation on dewaterability and extracellular polymeric substances of waste activated sludge.

    PubMed

    Peng, Ge; Ye, Fenxia; Ye, Yangfang

    2013-03-01

    The effects of microwave irradiation on filterability and dewaterability of waste activated sludge measured by capillary suction time (CST) and dry solids in sludge cake were investigated. The results showed that the optimum irradiation time improved filterability, but that further increase of the time was detrimental. Dewaterability was enhanced significantly and increased with microwave time. Filterability and dewaterability were improved 25 to 28% and 1.3 times at the optimum times of 30 and 90 seconds for the sludge of 5 g total suspended solids (TSS)/L and 7 g TSS/L, respectively. The floc size decreased slightly. Loosely bound extracellular polymeric substances (LB-EPS) decreased under optimum time, but tightly bound extracellular polymeric substances did not change significantly after short irradiation time. The results implied that LB-EPS played a more important role in the observed changes of filterability and dewaterability and that the double-layered extracellular polymeric substances extraction method showed marked implications to dewaterability. PMID:23581243

  7. Predictive Analysis of Landslide Activity Using Remote Sensing Data

    NASA Astrophysics Data System (ADS)

    Markuzon, N.; Regan, J.; Slesnick, C.

    2012-12-01

    Landslides are historically one of the most damaging geohazard phenomena in terms of death tolls and socio-economic losses. Therefore, understanding the underlying causes of landslides and how environmental phenomena affect their frequency and severity is of critical importance. Of specific importance for mitigating future damage is increasing our understanding of how climate change will affect landslide severity, occurrence rates, and damage. We are developing data driven models aimed at predicting landslide activity. The models learn multi-dimensional weather and geophysical patterns associated with historical landslides and estimate location-dependent probabilities for landslides under current or future weather and geophysical conditions. Our approach uses machine learning algorithms capable of determining non-linear associations between dependent variables and landslide occurrence without requiring detailed knowledge of geomorphology. Our primary goal in year one of the project is to evaluate the predictive capabilities of data mining models in application to landslide activity, and to analyze if the approach will discover previously unknown variables and/or relationships important to landslide occurrence, frequency or severity. The models include remote sensing and ground-based data, including weather, landcover, slope, elevation and drainage information as well as urbanization data. The historical landslide dataset we used to build our preliminary models was compiled from City of Seattle landslide files, United States Geological Survey reports, newspaper articles, and a verified subset of the Seattle Landslide Database that consists of all reported landslides within Seattle, WA, between 1948 and 1999. Most of the landslides analyzed to-date are shallow. Using statistical analysis and unsupervised clustering methods we have thus far identified subsets of weather conditions that lead to a significantly higher landslide probability, and have developed

  8. Ground-Based Passive Microwave Remote Sensing Observations of Soil Moisture at S and L Band with Insight into Measurement Accuracy

    NASA Technical Reports Server (NTRS)

    Laymon, Charles A.; Crosson, William L.; Jackson, Thomas J.; Manu, Andrew; Tsegaye, Teferi D.; Soman, V.; Arnold, James E. (Technical Monitor)

    2001-01-01

    Accurate estimates of spatially heterogeneous algorithm variables and parameters are required in determining the spatial distribution of soil moisture using radiometer data from aircraft and satellites. A ground-based experiment in passive microwave remote sensing of soil moisture was conducted in Huntsville, Alabama from July 1-14, 1996 to study retrieval algorithms and their sensitivity to variable and parameter specification. With high temporal frequency observations at S and L band, we were able to observe large scale moisture changes following irrigation and rainfall events, as well as diurnal behavior of surface moisture among three plots, one bare, one covered with short grass and another covered with alfalfa. The L band emitting depth was determined to be on the order of 0-3 or 0-5 cm below 0.30 cubic centimeter/cubic centimeter with an indication of a shallower emitting depth at higher moisture values. Surface moisture behavior was less apparent on the vegetated plots than it was on the bare plot because there was less moisture gradient and because of difficulty in determining vegetation water content and estimating the vegetation b parameter. Discrepancies between remotely sensed and gravimetric, soil moisture estimates on the vegetated plots point to an incomplete understanding of the requirements needed to correct for the effects of vegetation attenuation. Quantifying the uncertainty in moisture estimates is vital if applications are to utilize remotely-sensed soil moisture data. Computations based only on the real part of the complex dielectric constant and/or an alternative dielectric mixing model contribute a relatively insignificant amount of uncertainty to estimates of soil moisture. Rather, the retrieval algorithm is much more sensitive to soil properties, surface roughness and biomass.

  9. Synthesis of n-way active topology for wide-band RF/microwave applications

    NASA Astrophysics Data System (ADS)

    Ravelo, Blaise

    2012-05-01

    A novel architecture of n-way active topology for RF/microwave module applications is developed. This architecture is based on the use of active cell composed of a field effect transistor (FET) in cascade with shunt resistor. A theoretic analysis illustrating the S-parameters calculation was established. The expressions of the n-way power divider output gains were demonstrated. A synthesis method of active power-splitter or/and 180° balun in function of the considered FET stage number constituting each outer branch was proposed. A simple active power-splitter was designed using an even number of FET between the input-output branches. In addition, a variable gain active power-splitter was simulated. The FETs are biased at Vds = 6 V and Ids = 25 mA. So, insertion losses above -1.5 dB, return losses better than -15 dB and excellent isolation below -30 dB at all three ports were obtained from 0.5 to 5.5 GHz. Using odd number of FET stage, an active balun was realised. Then, simulations of active balun showing a perfectly constant differential out-phase (180° ± 5°), insertion losses above -1.5 dB and an excellent isolation below -30 dB for all three ports, from 0.3 to 4.5 GHz were performed.

  10. Investigation of atmospheric boundary layer temperature, turbulence, and wind parameters on the basis of passive microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Kadygrov, Evgeny N.; Shur, Genrih N.; Viazankin, Anton S.

    2003-06-01

    The MTP-5, a microwave temperature profiler, has been widely used since 1991 for investigation of the atmospheric boundary layer (ABL). The MTP-5 is an angular scanning single-channel instrument with a central frequency of about 60 GHz, designed to provide continuous, unattended observations. It can measure the thermal emission of the atmosphere with high sensitivity (0.03 K at 1 s integration time) from different zenith angles. On the basis of this measurement, it is possible to retrieve temperature profiles at the altitude range up to 600 m, to calculate wind speed and wind direction at the lowest 250 m, and to get information about some parameters of atmospheric turbulence. This report presents some applications of the MTP-5 instrument data collected in 1998-2001 within a number of international field projects: the dynamics of ABL temperature inversion in a mountain valley (Mesoscale Alpine Program (MAP)), as well as along an island coast (north part of Sakhalin Island, Russia-Japan Project); continuous measurements of the ABL temperature profile provided from a special scientific train that crossed the territory of Russia (the Transcontinental Observations of the Chemistry of the Atmosphere Project (TROICA)); and simultaneous measurements of the ABL temperature profile provided over the central and northern part of Moscow in a continuous mode (the Global Urban Research Meteorology and Environment Project (GURME)). In 1999, two MTP-5 instruments were installed on a platform that was rotating in the azimuth direction at the 310 m Obninsk Meteorological Research Tower (Meteo Tower) to validate the method and microwave equipment for measurement of wind speed and wind direction and investigation of atmospheric turbulence. Spectral analyses of the integrated signal provided an opportunity to estimate the inertial subrange low-frequency limit and its height dependence for thermal turbulence at the lowest 200 m layer. Wavelet analysis of the signal made it possible to

  11. The Challenge of Active Optical Sensing from Extreme Orbits

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.

    2004-01-01

    A review of the history and current state of atmospheric sensing lidar from Earth orbit was conducted and it was found that space based earth remote sensing is still in its infancy with only one limited success extended duration autonomous mission to date. An analysis of the basic requirements for some candidate geo-synchronous lidar concepts was completed and it was concluded that significant basic work is required in all areas of lidar development.

  12. Effects of low power microwave radiation on biological activity of Collagenase enzyme and growth rate of S. Cerevisiae yeast

    NASA Astrophysics Data System (ADS)

    Alsuhaim, Hamad S.; Vojisavljevic, Vuk; Pirogova, E.

    2013-12-01

    Recently, microwave radiation, a type/subset of non-ionizing electromagnetic radiation (EMR) has been widely used in industry, medicine, as well as food technology and mobile communication. Use of mobile phones is rapidly growing. Four years from now, 5.1 billion people will be mobile phone users around the globe - almost 1 billion more mobile users than the 4.3 billion people worldwide using them now. Consequently, exposure to weak radiofrequency/microwave radiation generated by these devices is markedly increasing. Accordingly, public concern about potential hazards on human health is mounting [1]. Thermal effects of radiofrequency/microwave radiation are very well-known and extensively studied. Of particular interest are non-thermal effects of microwave exposures on biological systems. Nonthermal effects are described as changes in cellular metabolism caused by both resonance absorption and induced EMR and are often accompanied by a specific biological response. Non-thermal biological effects are measurable changes in biological systems that may or may not be associated with adverse health effects. In this study we studied non-thermal effects of low power microwave exposures on kinetics of L-lactate dehydrogenase enzyme and growth rate of yeast Saccharomyces Cerevisiae strains type II. The selected model systems were continuously exposed to microwave radiation at the frequency of 968MHz and power of 10dBm using the designed and constructed (custom made) Transverse Electro-Magnetic (TEM) cell [2]. The findings reveal that microwave radiation at 968MHz and power of 10dBm inhibits L-lactate dehydrogenase enzyme activity by 26% and increases significantly (15%) the proliferation rate of yeast cells.

  13. Diurnal variations of stratospheric ozone measured by ground-based microwave remote sensing at the Mauna Loa NDACC site: measurement validation and GEOSCCM model comparison

    NASA Astrophysics Data System (ADS)

    Parrish, A.; Boyd, I. S.; Nedoluha, G. E.; Bhartia, P. K.; Frith, S. M.; Kramarova, N. A.; Connor, B. J.; Bodeker, G. E.; Froidevaux, L.; Shiotani, M.; Sakazaki, T.

    2013-12-01

    There is presently renewed interest in diurnal variations of stratospheric and mesospheric ozone for the purpose of supporting homogenization of records of various ozone measurements that are limited by the technique employed to being made at certain times of day. We have made such measurements for 18 yr using a passive microwave remote sensing technique at the Mauna Loa Observatory in Hawaii, which is a primary station in the Network for Detection of Atmospheric Composition Change (NDACC). We have recently reprocessed these data with hourly time resolution to study diurnal variations. We inspected differences between pairs of the ozone spectra (e.g. day and night) from which the ozone profiles are derived to determine the extent to which they may be contaminated by diurnally varying systematic instrumental or measurement effects. These are small, and we have reduced them further by selecting data that meet certain criteria that we established. We have calculated differences between profiles measured at different times: morning-night, afternoon-night, and morning-afternoon and have intercompared these with like profiles derived from Aura-MLS, UARS-MLS, SMILES, and SBUV/2 measurements. Differences between averages of coincident profiles are typically <1.5% of typical nightime values over most of the covered altitude range with some exceptions. We calculated averages of ozone values for each hour from the Mauna Loa microwave data, and normalized these to the average for the first hour after midnight for comparison with corresponding values calculated with the Goddard Earth Observing System Chemistry Climate Model (GEOSCCM). We found that the measurements and model output mostly agree to better than 1.5% of the midnight value, with one noteworthy exception: the measured morning-night values are significantly (2-3%) higher than the modeled ones from 3.2 to 1.8 hPa (~39-43 km), and there is evidence that the measured values are increasing compared to the modeled values

  14. Identification of sewage leaks by active remote-sensing methods

    NASA Astrophysics Data System (ADS)

    Goldshleger, Naftaly; Basson, Uri

    2016-04-01

    The increasing length of sewage pipelines, and concomitant risk of leaks due to urban and industrial growth and development is exposing the surrounding land to contamination risk and environmental harm. It is therefore important to locate such leaks in a timely manner, to minimize the damage. Advances in active remote sensing Ground Penetrating Radar (GPR) and Frequency Domain Electromagnetic (FDEM) technologies was used to identify leaking potentially responsible for pollution and to identify minor spills before they cause widespread damage. This study focused on the development of these electromagnetic methods to replace conventional acoustic methods for the identification of leaks along sewage pipes. Electromagnetic methods provide an additional advantage in that they allow mapping of the fluid-transport system in the subsurface. Leak-detection systems using GPR and FDEM are not limited to large amounts of water, but enable detecting leaks of tens of liters per hour, because they can locate increases in environmental moisture content of only a few percentage along the pipes. The importance and uniqueness of this research lies in the development of practical tools to provide a snapshot and monitoring of the spatial changes in soil moisture content up to depths of about 3-4 m, in open and paved areas, at relatively low cost, in real time or close to real time. Spatial measurements performed using GPR and FDEM systems allow monitoring many tens of thousands of measurement points per hectare, thus providing a picture of the spatial situation along pipelines and the surrounding. The main purpose of this study was to develop a method for detecting sewage leaks using the above-proposed geophysical methods, since their contaminants can severely affect public health. We focused on identifying, locating and characterizing such leaks in sewage pipes in residential and industrial areas.

  15. Using high-resolution soil moisture modelling to assess the uncertainty of microwave remotely sensed soil moisture products at the correct spatial and temporal support

    NASA Astrophysics Data System (ADS)

    Wanders, N.; Karssenberg, D.; Bierkens, M. F. P.; Van Dam, J. C.; De Jong, S. M.

    2012-04-01

    Soil moisture is a key variable in the hydrological cycle and important in hydrological modelling. When assimilating soil moisture into flood forecasting models, the improvement of forecasting skills depends on the ability to accurately estimate the spatial and temporal patterns of soil moisture content throughout the river basin. Space-borne remote sensing may provide this information with a high temporal and spatial resolution and with a global coverage. Currently three microwave soil moisture products are available: AMSR-E, ASCAT and SMOS. The quality of these satellite-based products is often assessed by comparing them with in-situ observations of soil moisture. This comparison is however hampered by the difference in spatial and temporal support (i.e., resolution, scale), because the spatial resolution of microwave satellites is rather low compared to in-situ field measurements. Thus, the aim of this study is to derive a method to assess the uncertainty of microwave satellite soil moisture products at the correct spatial support. To overcome the difference in support size between in-situ soil moisture observations and remote sensed soil moisture, we used a stochastic, distributed unsaturated zone model (SWAP, van Dam (2000)) that is upscaled to the support of different satellite products. A detailed assessment of the SWAP model uncertainty is included to ensure that the uncertainty in satellite soil moisture is not overestimated due to an underestimation of the model uncertainty. We simulated unsaturated water flow up to a depth of 1.5m with a vertical resolution of 1 to 10 cm and on a horizontal grid of 1 km2 for the period Jan 2010 - Jun 2011. The SWAP model was first calibrated and validated on in-situ data of the REMEDHUS soil moisture network (Spain). Next, to evaluate the satellite products, the model was run for areas in the proximity of 79 meteorological stations in Spain, where model results were aggregated to the correct support of the satellite

  16. Mapping UK snow accumulation using satellite passive microwave and visible-infrared remote sensing observations: two case studies from 2009 and 2010

    NASA Astrophysics Data System (ADS)

    Kelly, Richard

    2010-05-01

    In February 2009, an unusually significant snow storm deposited considerable amounts of snow in the UK for the first time in several years. A more persistent event deposited larger amounts of snow between December 2009 and January 2010; during this time snow cover duration exceeded a month in some locations and on 7 January, England Scotland and Wales were almost completely covered in snow as observed by NASA's Moderate Resolution Imaging Spectroradiometer (MODIS). Such widespread snow cover has not been observed since 1963 and 1979. Information about snow quantity and distribution in the UK is sparse and while some official observations are made, most observations are made through community-based observers or via more esoteric online social networks. Furthermore, daily snow accumulation maps are not easily obtainable for the UK. Coupled with unusually cold temperatures which began in mid December, these case studies provide an excellent opportunity to re-evaluate the role of satellite passive microwave observations for estimating snow water equivalent in the UK. Satellite remote sensing observations were obtained for the two snow event periods. MODIS observations are used to determine the location of the snow when cloud does not obscure the field of view. Passive microwave observations from the Advanced Microwave Scanning Radiometer - EOS (AMSR-E) are used to estimate SWE. In the first instance, AMSR-E estimates from the standard NASA algorithm are tested. On account of the documented radio frequency interference at 10 GHz the estimates are deemed unsuitable. A re-configured algorithm is developed at the native sampling resolution (10 km in along and across track) projected to a UTM grid. The re-configured approach to estimate SWE uses 18, 23 36 and 89GHz channels (vertical and horizontal polarization) and uses a frequency ratio approach, rather than difference, to minimize the physical temperature effect on brightness temperatures at 18, 36 and 89 GHz. It also

  17. Microwave acid digestion and preconcentration neutron activation analysis of biological and diet samples for iodine.

    PubMed

    Rao, R R; Chatt, A

    1991-07-01

    A simple preconcentration neutron activation analysis (PNAA) method has been developed for the determination of low levels of iodine in biological and nutritional materials. The method involves dissolution of the samples by microwave digestion in the presence of acids in closed Teflon bombs and preconcentration of total iodine, after reduction to iodide with hydrazine sulfate, by coprecipitation with bismuth sulfide. The effects of different factors such as acidity, time for complete precipitation, and concentrations of bismuth, sulfide, and diverse ions on the quantitative recovery of iodide have been studied. The absolute detection limit of the PNAA method is 5 ng of iodine. Precision of measurement, expressed in terms of relative standard deviation, is about 5% at 100 ppb and 10% at 20 ppb levels of iodine. The PNAA method has been applied to several biological reference materials and total diet samples. PMID:1897721

  18. Synthetic aperture microwave imaging with active probing for fusion plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Shevchenko, Vladimir F.; Freethy, Simon J.; Huang, Billy K.; Vann, Roddy G. L.

    2014-08-01

    A Synthetic Aperture Microwave Imaging (SAMI) system has been designed and built to obtain 2-D images at several frequencies from fusion plasmas. SAMI uses a phased array of linearly polarised antennas. The array configuration has been optimised to achieve maximum synthetic aperture beam efficiency. The signals received by antennas are down-converted to the intermediate frequency range and then recorded in a full vector form. Full vector signals allow beam focusing and image reconstruction in both real time and a post-processing mode. SAMI can scan over 16 pre-programmed frequencies in the range of 10-35GHz with a switching time of 300ns. The system operates in 2 different modes simultaneously: both a 'passive' imaging of plasma emission and also an 'active' imaging of the back-scattered signal of the radiation launched by one of the antennas from the same array. This second mode is similar to so-called Doppler backscattering (DBS) reflectometry with 2-D resolution of the propagation velocity of turbulent structures. Both modes of operation show good performance in fusion plasma experiments on Mega Amp Spherical Tokamak (MAST). We have obtained the first ever 2-D images of BXO mode conversion windows. With active probing, first ever turbulence velocity maps have been obtained. We present an overview of the diagnostic and discuss recent results. In contrast to quasi-optical microwave imaging systems SAMI requires neither big aperture viewing ports nor large 2-D detector arrays to achieve the desired imaging resolution. The number of effective 'pixels' of the synthesized image is proportional to the number of receiving antennas squared. Thus only a small number of optimised antennas is sufficient for the majority of applications. Possible implementation of SAMI on ITERand DEMO is discussed.

  19. Synthetic aperture microwave imaging with active probing for fusion plasma diagnostics

    SciTech Connect

    Shevchenko, Vladimir F.; Freethy, Simon J.; Huang, Billy K.

    2014-08-21

    A Synthetic Aperture Microwave Imaging (SAMI) system has been designed and built to obtain 2-D images at several frequencies from fusion plasmas. SAMI uses a phased array of linearly polarised antennas. The array configuration has been optimised to achieve maximum synthetic aperture beam efficiency. The signals received by antennas are down-converted to the intermediate frequency range and then recorded in a full vector form. Full vector signals allow beam focusing and image reconstruction in both real time and a post-processing mode. SAMI can scan over 16 pre-programmed frequencies in the range of 10-35GHz with a switching time of 300ns. The system operates in 2 different modes simultaneously: both a 'passive' imaging of plasma emission and also an 'active' imaging of the back-scattered signal of the radiation launched by one of the antennas from the same array. This second mode is similar to so-called Doppler backscattering (DBS) reflectometry with 2-D resolution of the propagation velocity of turbulent structures. Both modes of operation show good performance in fusion plasma experiments on Mega Amp Spherical Tokamak (MAST). We have obtained the first ever 2-D images of BXO mode conversion windows. With active probing, first ever turbulence velocity maps have been obtained. We present an overview of the diagnostic and discuss recent results. In contrast to quasi-optical microwave imaging systems SAMI requires neither big aperture viewing ports nor large 2-D detector arrays to achieve the desired imaging resolution. The number of effective 'pixels' of the synthesized image is proportional to the number of receiving antennas squared. Thus only a small number of optimised antennas is sufficient for the majority of applications. Possible implementation of SAMI on ITERand DEMO is discussed.

  20. Retrieval of Precipitation Profiles from Multiresolution, Multifrequency Active and Passive Microwave Observations.

    NASA Astrophysics Data System (ADS)

    Grecu, Mircea; Olson, William S.; Anagnostou, Emmanouil N.

    2004-04-01

    In this study, a technique for estimating vertical profiles of precipitation from multifrequency, multiresolution active and passive microwave observations is investigated. The technique is applicable to the Tropical Rainfall Measuring Mission (TRMM) observations, and it is based on models that simulate high-resolution brightness temperatures as functions of observed reflectivity profiles and a parameter related to the raindrop size distribution. The modeled high-resolution brightness temperatures are used to determine normalized brightness temperature polarizations at the microwave radiometer resolution. An optimal estimation procedure is employed to minimize the differences between the simulated and observed normalized polarizations by adjusting the drop size distribution parameter. The impact of other unknowns that are not independent variables in the optimal estimation, but affect the retrievals, is minimized through statistical parameterizations derived from cloud model simulations. The retrieval technique is investigated using TRMM observations collected during the Kwajalein Experiment (KWAJEX). These observations cover an area extending from 5° to 12°N latitude and from 166° to 172°E longitude from July to September 1999 and are coincident with various ground-based observations, facilitating a detailed analysis of the retrieved precipitation. Using the method developed in this study, precipitation estimates consistent with both the passive and active TRMM observations are obtained. Various parameters characterizing these estimates, that is, the rain rate, precipitation water content, drop size distribution intercept, and the mass- weighted mean drop diameter, are in good qualitative agreement with independent experimental and theoretical estimates. Combined rain estimates are, in general, higher than the official TRMM precipitation radar (PR)-only estimates for the area and the period considered in the study. Ground-based precipitation estimates, derived

  1. Phenolic Content and Antioxidant Activity of Extracts from Whole Buckwheat (Fagopyrum esculentum Moench) With or Without Microwave Irradiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of this study was to evaluate the effectiveness of extracting phenolic compounds and antioxidant activity from buckwheat with water, 50% aqueous ethanol, or 100% ethanol using microwave irradiation or a water bath for 15 min at various temperatures (23 – 150 °C). The phenolic content of...

  2. Role of the conducting layer substrate on TiO2 nucleation when using microwave activated chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Zumeta, I.; Espinosa, R.; Ayllón, J. A.; Vigil, E.

    2002-12-01

    Nanostructured TiO2 is used in novel dye sensitized solar cells. Because of their interaction with light, thin TiO2 films are also used as coatings for self-cleaning glasses and tiles. Microwave activated chemical bath deposition represents a simple and cost-effective way to obtain nanostructured TiO2 films. It is important to study, in this technique, the role of the conducting layer used as the substrate. The influence of microwave-substrate interactions on TiO2 deposition is analysed using different substrate positions, employing substrates with different conductivities, and also using different microwave radiation powers for film deposition. We prove that a common domestic microwave oven with a large cavity and inhomogeneous radiation field can be used with equally satisfactory results. The transmittance spectra of the obtained films were studied and used to analyse film thickness and to obtain gap energy values. The results, regarding different indium-tin oxide resistivities and different substrate positions in the oven cavity, show that the interaction of the microwave field with the conducting layer is determinant in layer deposition. It has also been found that film thickness increases with the power of the applied radiation while the gap energies of the TiO2 films decrease approaching the 3.2 eV value reported for bulk anatase. This indicates that these films are not crystalline and it agrees with x-ray spectra that do not reveal any peak.

  3. Upstream Anti-sense Promoters are Hubs of Transcription Factor Binding and Active Histone Modifications

    PubMed Central

    Scruggs, Benjamin S.; Gilchrist, Daniel A.; Nechaev, Sergei; Muse, Ginger W.; Burkholder, Adam; Fargo, David C.; Adelman, Karen

    2015-01-01

    SUMMARY Anti-sense transcription originating upstream of mammalian protein-coding genes is a well-documented phenomenon, but remarkably little is known about the regulation or function of anti-sense promoters and the non-coding RNAs they generate. Here we define at nucleotide resolution the divergent transcription start sites (TSSs) near mouse mRNA genes. We find that coupled sense and anti-sense TSSs precisely define the boundaries of a nucleosome-depleted region (NDR) that is highly enriched in transcription factor (TF) motifs. Notably, as the distance between sense and anti-sense TSSs increases, so does the size of the NDR, the level of signal-dependent TF binding and gene activation. We further discover a group of anti-sense TSSs in macrophages with an enhancer-like chromatin signature. Interestingly, this signature identifies divergent promoters that are activated during immune challenge. We propose that anti-sense promoters serve as platforms for TF binding and establishment of active chromatin to further regulate or enhance sense-strand mRNA expression. PMID:26028540

  4. Microwave remote sensing: Active and passive. Volume 2 - Radar remote sensing and surface scattering and emission theory

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Moore, R. K.; Fung, A. K.

    1982-01-01

    The fundamental principles of radar backscattering measurements are presented, including measurement statistics, Doppler and pulse discrimination techniques, and associated ambiguity functions. The operation of real and synthetic aperture sidelooking airborne radar systems is described, along with the internal and external calibration techniques employed in scattering measurements. Attention is given to the physical mechanisms responsible for the scattering emission behavior of homogeneous and inhomogeneous media, through a discussion of surface roughness, dielectric properties and inhomogeneity, and penetration depth. Simple semiempirical models are presented. Theoretical models involving greater mathematical sophistication are also given for extended ocean and bare soil surfaces, and the more general case of a vegetation canopy over a rough surface.

  5. Aircraft active and passive microwave validation of sea ice concentration from the Defense Meteorological Satellite Program special sensor microwave imager

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Crawford, J. P.; Drinkwater, M. R.; Eppler, D. T.; Farmer, L. D.; Jentz, R. R.; Wackerman, C. C.

    1991-01-01

    Results are presented of a series of coordinate special sensor microwave imager (SSM/I) underflights that were carried out during March 1988 with NASA and Navy aircraft over portions of the Bering, Beaufort, and Chukchi seas. NASA DC-8 AMMR data from Bering Sea ice edge crossings were used to verify that the ice edge location, defined as the position of the initial ice bands encountered by the aircraft, corresponds to an SSM/I ice concentration of 15 percent. Direct comparison of SSM/I and aircraft ice concentrations for regions having at least 80 percent aircraft coverage reveals that the SSM/I total ice concentration is lower on average by 2.4 +/-2.4 percent. For multiyear ice, NASA and Navy flights across the Beaufort and Chukchi seas show that the SSM/I algorithm correctly maps the large-scale distribution of multiyear ice: the zone of first-year ice off the Alaskan coast, the large areas of mixed first-year and multiyear ice, and the region of predominantly multiyear ice north of the Canadian archipelago.

  6. Bridging the Past with Today's Microwave Remote Sensing: A Case Study of Long Term Inundation Patterns in the Mekong River Delta

    NASA Astrophysics Data System (ADS)

    Jensen, K.; McDonald, K. C.; Schroeder, R.; Tessler, Z. D.

    2015-12-01

    Surface inundation extent and its predictability vary tremendously across the globe. This dynamic is being and has been captured by three general categories of satellite imagery: 1) low-spatial-resolution microwave sensors with global coverage and a long record of observations (e.g., SSM/I), 2) optical sensors with high spatial and temporal resolution and global coverage, but with cloud contamination (e.g. MODIS), and 3) in more ''snapshot'' form by high-resolution synthetic aperture radar (SAR) sensors. We explore the ability to bridge techniques that can exploit the higher spatial resolution of more recent data products back in time with the help of the temporal evolution of lower resolution products. We present a study of long term (20+ year) inundation patterns in the Mekong River Delta using baseline observations from the Surface Water Microwave Product Series (SWAMPS), an inundation area fraction product derived at 25km scale from active and passive microwave instruments (ERS, QuikSCAT, ASCAT, and SSM/I) that spans from Jan. 1992 to Jun. 2015. Every hydrological basin has unique characteristics - such as its topography, land cover / land use, and space-time variability - thus, a downscaling algorithm needs to take into account these idiosyncrasies. We merge SWAMPS with topographical information derived from 30m SRTM DEM, river networks from USGS HydroSHEDS, and assess the best statistical procedure to "learn" from two sets of classified SAR data: (1) L-band imaging radar from ALOS PALSAR, 2007-2010, and (2) C-band imagery from the Sentinel-1 mission (2014 to present). We present a comparison of retrospective downscaled flood extent with Landsat imagery and recent observations from SMAP. With a higher spatial resolution of past flooding extent, we can improve our understanding of how delta surface hydrology responds to local and regional events. This is important both in the short-term for accurate flood prediction, as well as on longer-term planning horizons.

  7. Rapid microwave-assisted synthesis of molecularly imprinted polymers on carbon quantum dots for fluorescent sensing of tetracycline in milk.

    PubMed

    Hou, Juan; Li, Huiyu; Wang, Long; Zhang, Ping; Zhou, Tianyu; Ding, Hong; Ding, Lan

    2016-01-01

    In this paper, a novel, selective and eco-friendly sensor for the detection of tetracycline was developed by grafting imprinted polymers onto the surface of carbon quantum dots. A simple microwave-assisted approach was utilized to fabricate the fluorescent imprinted composites rapidly for the first time, which could shorten the polymerization time and simplify the experimental procedure dramatically. The novel composites not only demonstrated excellent fluorescence stability and special binding sites, but also could selectively accumulate target analytes. Under optimal conditions, the relative fluorescence intensity of the composites decreased linearly with increasing the concentration of tetracycline from 20 nM to 14 µM. The detection limit of tetracycline was 5.48 nM. The precision and reproducibility of the proposed sensor were also acceptable. Significantly, the practicality of this ultrasensitive sensor for tetracycline detection in milk was further validated, revealing the advantages of simplicity, sensitivity, selectivity and low cost. This approach combines the high selective adsorption property of molecular imprinted polymers and the sensitivity of fluorescence detection. It is envisioned that the development of fluorescent molecularly imprinted composites will offer a new way of thinking for rapid analysis in complex samples. PMID:26695231

  8. Active Remote Sensing of Natural Resources: Course Notes. Science Series No. 5. Final Technical Report.

    ERIC Educational Resources Information Center

    Maxwell, Eugene L.

    Presented is a portion of a research project which developed materials for teaching remote sensing of natural resources on an interdisciplinary basis at the graduate level. This volume contains notes developed for a course in active remote sensing. It is concerned with those methods or systems which generate the electromagnetic energy…

  9. Medical applications of microwaves

    NASA Astrophysics Data System (ADS)

    Vrba, Jan; Lapes, M.

    2004-04-01

    Medical applications of microwaves (i.e. a possibility to use microwave energy and/or microwave technique and technology for therapeutical purposes) are a quite new and a very rapidly developing field. Microwave thermotherapy is being used in medicine for the cancer treatment and treatment of some other diseases since early eighties. In this contribution we would like to offer general overview of present activities in the Czech Republic, i.e. clinical applications and results, technical aspects of thermo therapeutic equipment and last but not least, prospective diagnostics based on microwave principals ant technology and instrumentation.

  10. Preparation of activated carbon from coconut shell chars in pilot-scale microwave heating equipment at 60 kW

    SciTech Connect

    Li Wei; Peng Jinhui Zhang Libo; Yang Kunbin; Xia Hongying; Zhang Shimin; Guo Shenghui

    2009-02-15

    Experiments to prepare activated carbon by microwave heating indicated that microwave energy can decrease reaction temperature, save the energy and shorten processing time remarkably compared to conventional heating, owing to its internal and volumetric heating effects. The above results were based on the laboratory-scale experiments. It is desirable to develop a pilot-scale microwave heating equipment and investigate the parameters with the aim of technological industrialization. In the present study, the components and features of the self-invented equipment were introduced. The temperature rise curves of the chars were obtained. Iodine numbers of the activated carbons all exceed the state standard of China under the following conditions: 25 kg/h charging rate, 0.42 rev/min turning rate of ceramic tube, flow rate of steam at pressure of 0.01 MPa and 40 kW microwave heating power after 60 kW pre-activation for 30 min. Pore structure of the sample obtained at a time point of 46 h, which contained BET surface area, and pore size distributions of micropores and total pores, was tested by nitrogen adsorption at 77 K.

  11. Experimental study on removal of NO using adsorption of activated carbon/reduction decomposition of microwave heating.

    PubMed

    Shuang-Chen, Ma; Yao, Juan-Juan; Gao, Li

    2012-01-01

    Experimental studies were carried out on flue gas denitrification using activated carbon irradiated by microwave. The effects of microwave irradiation power (reaction temperature), the flow rate of flue gas, the concentration of NO and the flue gas coexisting compositions on the adsorption property of activated carbon and denitrification efficiency were investigated. The results show that: the higher of microwave power, the higher of denitrification efficiency; denitrification efficiency would be greater than 99% and adsorption capacity of NO is relatively stable after seven times regeneration if the microwave power is more than 420 W; adsorption capacity of NO in activated carbon bed is 33.24 mg/g when the space velocity reaches 980 per hour; adsorption capacity declines with increasing of the flow rate of flue gas; the change in denitrification efficiency is not obvious with increasing oxygen content in the flue gas; and the maximum adsorption capacity of NO was observed when moisture in flue gas was about 5.88%. However, the removal efficiency of NO reduces with increasing moisture, and adsorption capacity and removal efficiency of NO reduce with increasing of SO2 concentration in the flue gas. PMID:22988643

  12. Activities of the Remote Sensing Information Sciences Research Group

    NASA Technical Reports Server (NTRS)

    Estes, J. E.; Botkin, D.; Peuquet, D.; Smith, T.; Star, J. L. (Principal Investigator)

    1984-01-01

    Topics on the analysis and processing of remotely sensed data in the areas of vegetation analysis and modelling, georeferenced information systems, machine assisted information extraction from image data, and artificial intelligence are investigated. Discussions on support field data and specific applications of the proposed technologies are also included.

  13. Sense of Cohesion among Community Activists Engaging in Volunteer Activity

    ERIC Educational Resources Information Center

    Levy, Drorit; Itzhaky, Haya; Zanbar, Lea; Schwartz, Chaya

    2012-01-01

    The present article attempts to shed light on the direct and indirect contribution of personal resources and community indices to Sense of Cohesion among activists engaging in community volunteer work. The sample comprised 481 activists. Based on social systems theory, three levels of variables were examined: (1) inputs, which included personal…

  14. Remote sensing research activities related to academic institutions

    NASA Technical Reports Server (NTRS)

    Myers, V. I.

    1980-01-01

    The role of research in the educational setting is discussed. Curriculum developments for integrating teaching and research are described. Remote sensing technology is used as an example of bridging the gap between research and application. Recommendations are presented for strengthing research groups.

  15. Monitoring boreal ecosystem phenology with integrated active/passive microwave remote sensing

    NASA Technical Reports Server (NTRS)

    McDonald, K. C.; Njoku, E.; Kimball, J.; Running, S.; Thompson, C.; Lee, J. K.

    2002-01-01

    The important role of the high latitudes in the functioning of global processes is becoming well established. The size and remoteness of arctic and boreal ecosystems, however, pose a challenge to quantification of both terrestrial ecosystem processes and their feedbacks to regional and global climate conditions. Boreal and arctic regions form a complex land cover mosaic where vegetation structure, condition and distribution are strongly regulated by environmental factors such as moisture availability, permafrost, growing season length, disturbance and soil nutrients.

  16. Acute low-level microwave exposure and central cholinergic activity: studies on irradiation parameters

    SciTech Connect

    Lai, H.; Horita, A.; Guy, A.W.

    1988-01-01

    Sodium-dependent high-affinity choline uptake was measured in the striatum, frontal cortex, hippocampus, and hypothalamus of rats after acute exposure (45 min) to pulsed (2 microseconds, 500 pps) or continuous-wave 2,450-MHz microwaves in cylindrical waveguides or miniature anechoic chambers. In all exposure conditions, the average whole-body specific absorption rate was at 0.6 W/kg. Decrease in choline uptake was observed in the frontal cortex after microwave exposure in all of the above irradiation conditions. Regardless of the exposure system used, hippocampal choline uptake was decreased after exposure to pulsed but not continuous-wave microwaves. Striatal choline uptake was decreased after exposure to either pulsed or continuous-wave microwaves in the miniature anechoic chamber. No significant change in hypothalamic choline uptake was observed under any of the exposure conditions studied. We conclude that depending on the parameters of the radiation, microwaves can elicit specific and generalized biological effects.

  17. An integrated approach to the remote sensing of floating ice

    NASA Technical Reports Server (NTRS)

    Campbell, W. J.; Ramseier, R. O.; Weeks, W. F.; Gloersen, P.

    1976-01-01

    Review article on remote sensing applications to glaciology. Ice parameters sensed include: ice cover vs open water, ice thickness, distribution and morphology of ice formations, vertical resolution of ice thickness, ice salinity (percolation and drainage of brine; flushing of ice body with fresh water), first-year ice and multiyear ice, ice growth rate and surface heat flux, divergence of ice packs, snow cover masking ice, behavior of ice shelves, icebergs, lake ice and river ice; time changes. Sensing techniques discussed include: satellite photographic surveys, thermal IR, passive and active microwave studies, microwave radiometry, microwave scatterometry, side-looking radar, and synthetic aperture radar. Remote sensing of large aquatic mammals and operational ice forecasting are also discussed.

  18. Microwave hydrology: A trilogy

    NASA Technical Reports Server (NTRS)

    Stacey, J. M.; Johnston, E. J.; Girard, M. A.; Regusters, H. A.

    1985-01-01

    Microwave hydrology, as the term in construed in this trilogy, deals with the investigation of important hydrological features on the Earth's surface as they are remotely, and passively, sensed by orbiting microwave receivers. Microwave wavelengths penetrate clouds, foliage, ground cover, and soil, in varying degrees, and reveal the occurrence of standing liquid water on and beneath the surface. The manifestation of liquid water appearing on or near the surface is reported by a microwave receiver as a signal with a low flux level, or, equivalently, a cold temperature. Actually, the surface of the liquid water reflects the low flux level from the cosmic background into the input terminals of the receiver. This trilogy describes and shows by microwave flux images: the hydrological features that sustain Lake Baykal as an extraordinary freshwater resource; manifestations of subsurface water in Iran; and the major water features of the Congo Basin, a rain forest.

  19. Shape effect on the antibacterial activity of silver nanoparticles synthesized via a microwave-assisted method.

    PubMed

    Hong, Xuesen; Wen, Junjie; Xiong, Xuhua; Hu, Yongyou

    2016-03-01

    Silver nanoparticles (AgNPs) are used as sustained-release bactericidal agents for water treatment. Among the physicochemical characteristics of AgNPs, shape is an important parameter relevant to the antibacterial activity. Three typically shaped AgNPs, nanocubes, nanospheres, and nanowires, were prepared via a microwave-assisted method and characterized by TEM, UV-vis, and XRD. The antibacterial activity of AgNPs was determined by OD growth curves tests, MIC tests, and cell viability assay against Escherichia coli. The interaction between AgNPs and bacterial cells was observed by TEM. The results showed that the three differently shaped AgNPs were nanoscale, 55 ± 10 nm in edge length for nanocubes, 60 ± 15 nm in diameter for nanospheres, 60 ± 10 nm in diameter and 2-4 μm in length for nanowires. At the bacterial concentration of 10(4) CFU/mL, the MIC of nanocubes, nanospheres, and nanowires were 37.5, 75, and 100 μg/mL, respectively. Due to the worst contact with bacteria, silver nanowires exhibited the weakest antibacterial activity compared with silver nanocubes and silver nanospheres. Besides, silver nanocubes mainly covered by {100} facets showed stronger antibacterial activity than silver nanospheres covered by {111} facets. It suggests that the shape effect on the antibacterial activity of AgNPs is attributed to the specific surface areas and facets reactivity; AgNPs with larger effective contact areas and higher reactive facets exhibit stronger antibacterial activity. PMID:26511259

  20. Comparison between Neural Network and Fuzzy Logic system for Soil Moisture Estimation using Microwave Remote Sensing Data

    NASA Astrophysics Data System (ADS)

    Lakhankar, T. Y.; Ghedira, H.; Khanbilvardi, R. M.

    2004-12-01

    Artificial neural networks and Fuzzy logic have been applied to a wide range of problems in several disciplines. They have been successfully applied to image processing, and have shown a great potential in the classification of remote sensing data. However, a successful application of these methods in remote sensing data classification requires a good comprehension of the effect of their internal parameters and especially those that are related to the algorithm structure and to the training process. In this work we report the application of backpropagation neural network and fuzzy logic in estimating the soil moisture level using Synthetic Aperture Radar (SAR) data. The potential of SAR images in spatial soil moisture estimation depends on the ability of these algorithms to define the complex relationship that exists between the backscattered energy and the moisture content of the soil. A study area located in Oklahoma (97d35'W, 36d15'N) has been chosen for this project. Several textural measures derived from Radarsat-1 images acquired in Scansar Mode during the summer of 1997 were used as input for two algorithms. The soil moisture data measured by ESTAR Instrument (Electronically Scanned Thinned Array Radiometer) during the SGP97 campaign (operated by NASA) were used as truth data in the training process. The effect of some parameters related to the training process on classification performance was investigated for both methods. The preliminary results showed that for neural networks, the variations of the number of hidden layers and the number of nodes by layer have no significant effect on classification accuracy. However, the retained threshold value used in the output layer affects significantly the overall classification. Concerning, the fuzzy logic algorithm, the preliminary results showed that the cluster radius selection have a significant effect on classification accuracy.

  1. Microwave-assisted preparation and adsorption performance of activated carbon from biodiesel industry solid reside: influence of operational parameters.

    PubMed

    Foo, K Y; Hameed, B H

    2012-01-01

    Preparation of activated carbon has been attempted using KOH as activating agent by microwave heating from biodiesel industry solid residue, oil palm empty fruit bunch (EFBAC). The significance of chemical impregnation ratio (IR), microwave power and activation time on the properties of activated carbon were investigated. The optimum condition has been identified at the IR of 1.0, microwave power of 600 W and activation time of 7 min. EFBAC was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement, determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue as dye model compound. The optimum conditions resulted in activated carbon with a monolayer adsorption capacity of 395.30 mg/g and carbon yield of 73.78%, while the BET surface area and total pore volume were corresponding to 1372 m2/g and 0.76 cm3/g, respectively. PMID:22050840

  2. Active Ground Optical Remote Sensing for Improved Monitoring of Seedling Stress in Nurseries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Active ground optical remote sensing (AGORS) devices mounted on overhead irrigation booms could help to improve seedling quality by autonomously monitoring seedling stress. In contrast to traditionally used passive optical sensors, AGORS devices operate independently of ambient light conditions and ...

  3. Modeling Chemical Detection Sensitivities of Active and Passive Remote Sensing Systems

    SciTech Connect

    Scharlemann, E T

    2003-07-28

    During nearly a decade of remote sensing programs under the auspices of the U. S. Department of Energy (DOE), LLNL has developed a set of performance modeling codes--called APRS--for both Active and Passive Remote Sensing systems. These codes emphasize chemical detection sensitivity in the form of minimum detectable quantities with and without background spectral clutter and in the possible presence of other interfering chemicals. The codes have been benchmarked against data acquired in both active and passive remote sensing programs at LLNL and Los Alamos National Laboratory (LANL). The codes include, as an integral part of the performance modeling, many of the data analysis techniques developed in the DOE's active and passive remote sensing programs (e.g., ''band normalization'' for an active system, principal component analysis for a passive system).

  4. Quorum Sensing Activity of Enterobacter asburiae Isolated from Lettuce Leaves

    PubMed Central

    Lau, Yin Yin; Sulaiman, Joanita; Chen, Jian Woon; Yin, Wai-Fong; Chan, Kok-Gan

    2013-01-01

    Bacterial communication or quorum sensing (QS) is achieved via sensing of QS signaling molecules consisting of oligopeptides in Gram-positive bacteria and N-acyl homoserine lactones (AHL) in most Gram-negative bacteria. In this study, Enterobacteriaceae isolates from Batavia lettuce were screened for AHL production. Enterobacter asburiae, identified by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) was found to produce short chain AHLs. High resolution triple quadrupole liquid chromatography mass spectrometry (LC/MS) analysis of the E. asburiae spent supernatant confirmed the production of N-butanoyl homoserine lactone (C4-HSL) and N–hexanoyl homoserine lactone (C6-HSL). To the best of our knowledge, this is the first report of AHL production by E. asburiae. PMID:24152877

  5. Hybrid architecture active wavefront sensing and control system, and method

    NASA Technical Reports Server (NTRS)

    Feinberg, Lee D. (Inventor); Dean, Bruce H. (Inventor); Hyde, Tristram T. (Inventor)

    2011-01-01

    According to various embodiments, provided herein is an optical system and method that can be configured to perform image analysis. The optical system can comprise a telescope assembly and one or more hybrid instruments. The one or more hybrid instruments can be configured to receive image data from the telescope assembly and perform a fine guidance operation and a wavefront sensing operation, simultaneously, on the image data received from the telescope assembly.

  6. Coordinated sensing and active repair for self-healing

    NASA Astrophysics Data System (ADS)

    Hurley, D. A.; Huston, D. R.

    2011-02-01

    Self-repairing structural systems have the potential for improved performance ranges and lifetimes over conventional systems. Self-healing materials are not a new phenomenon and have been used in automotive and aeronautical applications for over a century. The bulk of these systems operate by using damage to directly initiate a repair response without any supervisory coordination. Integrating sensing and supervisory control technologies with self-healing may improve the safety and reliability of critical components and structures. This project illustrates the benefit of an integrated sensing, control, and self-healing system using laboratory scale test beds. A thermoplastic polymer embedded with resistive heating wires acts as the self-healing material. Damage is detected using an electro-optical sensing scheme based on photoresistors and a PC handling control duties. As damage occurs it is detected, located, and characterized. The key to this project is the integration of sensor feedback to control healing so that repairs are executed, monitored, and completed on the basis of continuous sensor data. This proof-of-concept prototype can likely be expanded and improved with alternative sensor options, self-healing materials, and system architecture.

  7. Microwave-assisted synthesis of 4'-azaflavones and their N-alkyl derivatives with biological activities.

    PubMed

    Yaşar, Ahmet; Akpinar, Kurtuluş; Burnaz, Nesibe Arslan; Küçük, Murat; Karaoğlu, Sengül Alpay; Doğan, Neşe; Yayli, Nurettin

    2008-05-01

    4'-Azaflavone (=2-(pyridin-4-yl)-4H-1-benzopyran-4-one; 4) and 3-[(pyridin-4-yl)methyl]-4'-azaflavone (5) were synthesized by a simple environmentally friendly microwave-assisted one-pot method through the cyclization of 3-hydroxy-1-(2-hydroxyphenyl)-3-(pyridin-4-yl)propan-1-one (1), (E)-2'-hydroxy-4-azachalcone (2; chalcone=1,3-diphenylprop-2-en-1-one), and 2'-hydroxy-2-[(hydroxy)(pyridin-4-yl)methyl]-4''-azachalcone (3) under solventless conditions using silica-supported NaHSO(4), followed by treatment with base. In addition, N-alkyl-substituted 4'-azaflavonium bromides 6 and 7 were prepared from compounds 4 and 5, respectively. The antimicrobial and antioxidant activities of compounds 1-7 were tested. The N-alkyl-substituted 4'-azaflavonium bromides 6 and 7 showed high antimicrobial activity against the Gram-positive bacteria and the fungus tested, with MIC values close to those of reference antimicrobials ampicilline and fluconazole. The alkylated compounds 6 and 7 also showed a good antioxidant character in the two antioxidant methods, DPPH (=1,1-diphenyl-2-picrylhydrazyl) radical-scavenging and ferric reducing/antioxidant power (FRAP) tests. PMID:18493968

  8. Microwave plasma doping: Arsenic activation and transport in germanium and silicon

    NASA Astrophysics Data System (ADS)

    Miyoshi, Hidenori; Oka, Masahiro; Ueda, Hirokazu; Ventzek, Peter L. G.; Sugimoto, Yasuhiro; Kobayashi, Yuuki; Nakamura, Genji; Hirota, Yoshihiro; Kaitsuka, Takanobu; Kawakami, Satoru

    2016-04-01

    Microwave RLSA™ plasma doping technology has enabled conformal doping of non-planar semiconductor device structures. An important attribute of RLSA™ plasma doping is that it does not impart physical damage during processing. In this work, carrier activation measurements for AsH3 based plasma doping into silicon (Si) and germanium (Ge) using rapid thermal annealing are presented. The highest carrier concentrations are 3.6 × 1020 and 4.3 × 1018 cm-3 for Si and Ge, respectively. Secondary ion mass spectrometry depth profiles of arsenic in Ge show that intrinsic dopant diffusion for plasma doping followed by post activation anneal is much slower than for conventional ion implantation. This is indicative of an absence of defects. The comparison is based on a comparison of diffusion times at identical annealing temperatures. The absence of defects, like those generated in conventional ion implantation, in RLSA™ based doping processes makes RLSA™ doping technology useful for damage free conformal doping of topographic structures.

  9. Microwave synthesis and photocatalytic activity of Tb(3+) doped BiVO4 microcrystals.

    PubMed

    Wang, Ying; Liu, Fuyang; Hua, Yingjie; Wang, Chongtai; Zhao, Xudong; Liu, Xiaoyang; Li, Hongdong

    2016-12-01

    Tb(3+) doped BiVO4 has been successfully synthesized by a simple microwave-assisted hydrothermal method at 140°C for 30min. The structure, morphology and optical property of the Tb(3+) doped BiVO4 products have been systematically investigated. This study indicates that the incorporation of Tb(3+) could induce the conversion of structure from monoclinic to tetragonal for BiVO4. Furthermore, the as-obtained Tb(3+) doped BiVO4 samples showed an obvious morphological change: the hollow square rod-like BiVO4 crystal gradually changed to spindle-like crystal. The Tb(3+) doped BiVO4 products exhibited extraordinary photocatalytic activity for Methylene Blue (MB) degradation under visible light irradiation. The doped BiVO4 at a molar ratio of 2at% (Tb and Bi) with a mixture of monoclinic and tetragonal phases showed and prominent photocatalytic degradation rate, which reached 99.9% in 120min. The results suggest that the differences in the photocatalytic activity of these BiVO4 crystals with different Tb(3+) doping concentrations can be attributed to the change of crystalline phases, and the coexistence of the monoclinic/tetragonal phases in BiVO4 products, which improve the efficient charge separation and transportation. PMID:27565962

  10. Monitoring of Vibrio harveyi quorum sensing activity in real time during infection of brine shrimp larvae

    PubMed Central

    Defoirdt, Tom; Sorgeloos, Patrick

    2012-01-01

    Quorum sensing, bacterial cell-to-cell communication, has been linked to the virulence of pathogenic bacteria. Indeed, in vitro experiments have shown that many bacterial pathogens regulate the expression of virulence genes by this cell-to-cell communication process. Moreover, signal molecules have been detected in samples retrieved from infected hosts and quorum sensing disruption has been reported to result in reduced virulence in different host–pathogen systems. However, data on in vivo quorum sensing activity of pathogens during infection of a host are currently lacking. We previously reported that quorum sensing regulates the virulence of Vibrio harveyi in a standardised model system with gnotobiotic brine shrimp (Artemia franciscana) larvae. Here, we monitored quorum sensing activity in Vibrio harveyi during infection of the shrimp, using bioluminescence as a read-out. We found that wild-type Vibrio harveyi shows a strong increase in quorum sensing activity early during infection. In this respect, the bacteria behave remarkably similar in different larvae, despite the fact that only half of them survive the infection. Interestingly, when expressed per bacterial cell, Vibrio harveyi showed around 200-fold higher maximal quorum sensing-regulated bioluminescence when associated with larvae than in the culture water. Finally, the in vivo quorum sensing activity of mutants defective in the production of one of the three signal molecules is consistent with their virulence, with no detectable in vivo quorum sensing activity in AI-2- and CAI-1-deficient mutants. These results indicate that AI-2 and CAI-1 are the dominant signals during infection of brine shrimp. PMID:22673627

  11. Monitoring of Vibrio harveyi quorum sensing activity in real time during infection of brine shrimp larvae.

    PubMed

    Defoirdt, Tom; Sorgeloos, Patrick

    2012-12-01

    Quorum sensing, bacterial cell-to-cell communication, has been linked to the virulence of pathogenic bacteria. Indeed, in vitro experiments have shown that many bacterial pathogens regulate the expression of virulence genes by this cell-to-cell communication process. Moreover, signal molecules have been detected in samples retrieved from infected hosts and quorum sensing disruption has been reported to result in reduced virulence in different host-pathogen systems. However, data on in vivo quorum sensing activity of pathogens during infection of a host are currently lacking. We previously reported that quorum sensing regulates the virulence of Vibrio harveyi in a standardised model system with gnotobiotic brine shrimp (Artemia franciscana) larvae. Here, we monitored quorum sensing activity in Vibrio harveyi during infection of the shrimp, using bioluminescence as a read-out. We found that wild-type Vibrio harveyi shows a strong increase in quorum sensing activity early during infection. In this respect, the bacteria behave remarkably similar in different larvae, despite the fact that only half of them survive the infection. Interestingly, when expressed per bacterial cell, Vibrio harveyi showed around 200-fold higher maximal quorum sensing-regulated bioluminescence when associated with larvae than in the culture water. Finally, the in vivo quorum sensing activity of mutants defective in the production of one of the three signal molecules is consistent with their virulence, with no detectable in vivo quorum sensing activity in AI-2- and CAI-1-deficient mutants. These results indicate that AI-2 and CAI-1 are the dominant signals during infection of brine shrimp. PMID:22673627

  12. Urban rainfall estimation employing commercial microwave links

    NASA Astrophysics Data System (ADS)

    Overeem, Aart; Leijnse, Hidde; Uijlenhoet, Remko; ten Veldhuis, Marie-claire

    2015-04-01

    Urban areas often lack rainfall information. To increase the number of rainfall observations in cities, microwave links from operational cellular telecommunication networks may be employed. Although this new potential source of rainfall information has been shown to be promising, its quality needs to be demonstrated more extensively. In the Rain Sense kickstart project of the Amsterdam Institute for Advanced Metropolitan Solutions (AMS), sensors and citizens are preparing Amsterdam for future weather. Part of this project is rainfall estimation using new measurement techniques. Innovative sensing techniques will be utilized such as rainfall estimation from microwave links, umbrellas for weather sensing, low-cost sensors at lamp posts and in drainage pipes for water level observation. These will be combined with information provided by citizens in an active way through smartphone apps and in a passive way through social media posts (Twitter, Flickr etc.). Sensor information will be integrated, visualized and made accessible to citizens to help raise citizen awareness of urban water management challenges and promote resilience by providing information on how citizens can contribute in addressing these. Moreover, citizens and businesses can benefit from reliable weather information in planning their social and commercial activities. In the end city-wide high-resolution rainfall maps will be derived, blending rainfall information from microwave links and weather radars. This information will be used for urban water management. This presentation focuses on rainfall estimation from commercial microwave links. Received signal levels from tens of microwave links within the Amsterdam region (roughly 1 million inhabitants) in the Netherlands are utilized to estimate rainfall with high spatial and temporal resolution. Rainfall maps will be presented and compared to a gauge-adjusted radar rainfall data set. Rainfall time series from gauge(s), radars and links will be compared.

  13. Classification methods for monitoring Arctic sea ice using OKEAN passive/active two-channel microwave data

    USGS Publications Warehouse

    Belchansky, Gennady I.; Douglas, David C.

    2000-01-01

    This paper presents methods for classifying Arctic sea ice using both passive and active (2-channel) microwave imagery acquired by the Russian OKEAN 01 polar-orbiting satellite series. Methods and results are compared to sea ice classifications derived from nearly coincident Special Sensor Microwave Imager (SSM/I) and Advanced Very High Resolution Radiometer (AVHRR) image data of the Barents, Kara, and Laptev Seas. The Russian OKEAN 01 satellite data were collected over weekly intervals during October 1995 through December 1997. Methods are presented for calibrating, georeferencing and classifying the raw active radar and passive microwave OKEAN 01 data, and for correcting the OKEAN 01 microwave radiometer calibration wedge based on concurrent 37 GHz horizontal polarization SSM/I brightness temperature data. Sea ice type and ice concentration algorithms utilized OKEAN's two-channel radar and passive microwave data in a linear mixture model based on the measured values of brightness temperature and radar backscatter, together with a priori knowledge about the scattering parameters and natural emissivities of basic sea ice types. OKEAN 01 data and algorithms tended to classify lower concentrations of young or first-year sea ice when concentrations were less than 60%, and to produce higher concentrations of multi-year sea ice when concentrations were greater than 40%, when compared to estimates produced from SSM/I data. Overall, total sea ice concentration maps derived independently from OKEAN 01, SSM/I, and AVHRR satellite imagery were all highly correlated, with uniform biases, and mean differences in total ice concentration of less than four percent (sd<15%).

  14. Variations of mesoscale and large-scale sea ice morphology in the 1984 Marginal Ice Zone Experiment as observed by microwave remote sensing

    NASA Technical Reports Server (NTRS)

    Campbell, W. J.; Josberger, E. G.; Gloersen, P.; Johannessen, O. M.; Guest, P. S.

    1987-01-01

    The data acquired during the summer 1984 Marginal Ice Zone Experiment in the Fram Strait-Greenland Sea marginal ice zone, using airborne active and passive microwave sensors and the Nimbus 7 SMMR, were analyzed to compile a sequential description of the mesoscale and large-scale ice morphology variations during the period of June 6 - July 16, 1984. Throughout the experiment, the long ice edge between northwest Svalbard and central Greenland meandered; eddies were repeatedly formed, moved, and disappeared but the ice edge remained within a 100-km-wide zone. The ice pack behind this alternately diffuse and compact edge underwent rapid and pronounced variations in ice concentration over a 200-km-wide zone. The high-resolution ice concentration distributions obtained in the aircraft images agree well with the low-resolution distributions of SMMR images.

  15. Making sense(s) in dementia: a multisensory and motor-based group activity program.

    PubMed

    Cruz, Joana; Marques, Alda; Barbosa, Ana; Figueiredo, Daniela; Sousa, Liliana X

    2013-03-01

    Lack of engagement in meaningful activities is associated with poor quality of life in dementia; thus, the development of these activities has been recommended. This pilot study aimed to develop a multisensory and motor-based group activity program for residents with dementia and assess its impact on residents' behavior. The program was designed using a multisensory and motor-based approach in sixteen 45-minute weekly sessions tailored to residents' characteristics. Four residents with advanced dementia participated in the program. The frequency and duration of the residents' behavior were assessed using video recordings. All residents participated in the proposed activities, although they were more participative and communicative in some sessions than in others. Group activity programs based on multisensory and motor stimulation can be a promising approach for people with advanced dementia; however, further research is needed. This study may serve as reference to the implementation of future programs aiming to increase person-centeredness of the care provided. PMID:23307794

  16. A New Way of Sensing: Need-Based Activation of Antibiotic Resistance by a Flux-Sensing Mechanism

    PubMed Central

    Fritz, Georg; Dintner, Sebastian; Treichel, Nicole Simone; Radeck, Jara; Gerland, Ulrich; Gebhard, Susanne

    2015-01-01

    ABSTRACT Sensing of and responding to environmental changes are of vital importance for microbial cells. Consequently, bacteria have evolved a plethora of signaling systems that usually sense biochemical cues either via direct ligand binding acting as “concentration sensors” or by responding to downstream effects on bacterial physiology, such as structural damage to the cell. Here, we describe a novel, alternative signaling mechanism that effectively implements a “flux sensor” to regulate antibiotic resistance. It relies on a sensory complex consisting of a histidine kinase and an ABC transporter, in which the transporter fulfills the dual role of both the sensor of the antibiotic and the mediator of resistance against it. Combining systems biological modeling with in vivo experimentation, we show that these systems in fact respond to changes in activity of individual resistance transporters rather than to changes in the antibiotic concentration. Our model shows that the cell thereby adjusts the rate of de novo transporter synthesis to precisely the level needed for protection. Such a flux-sensing mechanism may serve as a cost-efficient produce-to-demand strategy, controlling a widely conserved class of antibiotic resistance systems. PMID:26199330

  17. Young Scientists Explore the Five Senses. Book 4--Intermediate Level. A Good Apple Activity Book.

    ERIC Educational Resources Information Center

    DeBruin, Jerry

    Designed to develop creativity in young learners, this book contains interdisciplinary activities which focus on the theme of the five senses. Activity pages are provided that can serve as front and back covers of a student booklet and the suggested activities can be duplicated for insertion between the covers resulting in a booklet for each…

  18. Frequency requirements for active earth observation sensors

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The foundation and rationale for the selection of microwave frequencies for active remote sensing usage and for subsequent use in determination of sharing criteria and allocation strategies for the WARC-79 are presented.

  19. Permafrost vulnerability and active layer thickness increases over the high northern latitudes inferred from satellite remote sensing and process model assessments

    NASA Astrophysics Data System (ADS)

    Park, Hotaek; Kim, Youngwook

    2016-04-01

    Permafrost extent (PE) and active layer thickness (ALT) are important for assessing high northern latitude (HNL) ecological and hydrological processes, and potential land-atmosphere carbon and climate feedbacks. We developed a new approach to infer PE from satellite microwave remote sensing of daily landscape freeze-thaw (FT) status. Our results document, for the first time, the use of satellite microwave FT observations for monitoring permafrost extent and condition. The FT observations define near-surface thermal status used to determine permafrost extent and stability over a 30-year (1980-2009) satellite record. The PE results showed similar performance against independent inventory and process model (CHANGE) estimates, but with larger differences over heterogeneous permafrost subzones. A consistent decline in the ensemble mean of permafrost areas (‑0.33 million km2 decade‑1; p < 0.05) coincides with regional warming (0.4 °C decade‑1; p < 0.01), while more than 40% (9.6 million km2) of permafrost areas are vulnerable to degradation based on the 30-year PE record. ALT estimates determined from satellite (MODIS) and ERA-Interim temperatures, and CHANGE simulations, compared favorably with independent field observations and indicate deepening ALT trends consistent with widespread permafrost degradation under recent climate change. The integration of remote sensing and modeling of permafrost and active layer conditions developed from this study may facilitate regular and effective regional monitoring of these parameters, and expand applications of remote sensing for examining permafrost-related feedbacks and consequences for biogeochemical and hydrological cycling in the Arctic.

  20. Microwave-assisted digestion using nitric acid for heavy metals and sulfated ash testing in active pharmaceutical ingredients.

    PubMed

    Pluhácek, T; Hanzal, J; Hendrych, J; Milde, D

    2016-04-01

    The monitoring of inorganic impurities in active pharmaceutical ingredients plays a crucial role in the quality control of the pharmaceutical production. The heavy metals and residue on ignition/sulfated ash methods employing microwave-assisted digestion with concentrated nitric acid have been demonstrated as alternatives to inappropriate compendial methods recommended in United States Pharmacopoeia (USP) and European Pharmacopoeia (Ph. Eur.). The recoveries using the heavy metals method ranged between 89% and 122% for nearly all USP and Ph. Eur. restricted elements as well as the recoveries of sodium sulfate spikes were around 100% in all tested matrices. The proposed microwave-assisted digestion method allowed simultaneous decomposition of 15 different active pharmaceutical ingredients with sample weigh up to 1 g. The heavy metals and sulfated ash procedures were successfully applied to the determination of heavy metals and residue on ignition/sulfated ash content in mycophenolate mofetil, nicergoline and silymarin. PMID:27209695

  1. P-doped TiO2 with superior visible-light activity prepared by rapid microwave hydrothermal method

    NASA Astrophysics Data System (ADS)

    Niu, Jinfen; Lu, Pan; Kang, Mei; Deng, Kunfa; Yao, Binghua; Yu, Xiaojiao; Zhang, Qian

    2014-11-01

    Phosphorous-doped anatase TiO2 powders (P-TiO2) were prepared by rapid microwave hydrothermal method. The resulting materials were characterized by XRD, SEM, XPS, DRS and N2 adsorption. P-doping decreased the band gap and enlarged the surface area of P-doped samples than that of undoped TiO2 samples. Therefore, the photocatalytic degradation of methyl blue (MB) and tetracycline hydrochloride (Tc) experiments showed that the P-TiO2 catalysts, especially the two-steps-controlling products P-TiO2-2, exhibited higher degradation efficiency than the undoped TiO2 and commercial P25 under visible-light irradiation. Hydroxyl radicals (rad OH) have been confirmed to be the active species during the photocatalytic oxidation reaction. The microwave hydrothermal method confirms to be very suitable for the synthesis of superior visible-light activity P-doped samples.

  2. Active microwave measurements of sea ice under fall conditions: The RADARSAT/FIREX fall experiment. [in the Canadian Arctic

    NASA Technical Reports Server (NTRS)

    Onstott, R. G.; Kim, Y. S.; Moore, R. K.

    1984-01-01

    A series of measurements of the active microwave properties of sea ice under fall growing conditions was conducted. Ice in the inland waters of Mould Bay, Crozier Channel, and intrepid inlet and ice in the Arctic Ocean near Hardinge Bay was investigated. Active microwave data were acquired using a helicopter borne scatterometer. Results show that multiyear ice frozen in grey or first year ice is easily detected under cold fall conditions. Multiyear ice returns were dynamic due to response to two of its scene constituents. Floe boundaries between thick and thin ice are well defined. Multiyear pressure ridge returns are similar in level to background ice returns. Backscatter from homogeneous first year ice is seen to be primarily due to surface scattering. Operation at 9.6 GHz is more sensitive to the detailed changes in scene roughness, while operation at 5.6 GHz seems to track roughness changes less ably.

  3. Microwave-assisted silica coating and photocatalytic activities of ZnO nanoparticles

    SciTech Connect

    Siddiquey, Iqbal Ahmed; Furusawa, Takeshi; Sato, Masahide; Suzuki, Noboru

    2008-12-01

    A new and rapid method for silica coating of ZnO nanoparticles by the simple microwave irradiation technique is reported. Silica-coated ZnO nanoparticles were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), CHN elemental analysis and zeta potential measurements. The FT-IR spectra and XPS clearly confirmed the silica coating on ZnO nanoparticles. The results of XPS analysis showed that the elements in the coating at the surface of the ZnO nanoparticles were Zn, O and Si. HR-TEM micrographs revealed a continuous and uniform dense silica coating layer of about 3 nm in thickness on the surface of ZnO nanoparticles. In addition, the silica coating on the ZnO nanoparticles was confirmed by the agreement in the zeta potential of the silica-coated ZnO nanoparticles with that of SiO{sub 2}. The results of the photocatalytic degradation of methylene blue (MB) in aqueous solution showed that silica coating effectively reduced the photocatalytic activity of ZnO nanoparticles. Silica-coated ZnO nanoparticles showed excellent UV shielding ability and visible light transparency.

  4. Retrieval of Precipitation Profiles from Multiresolution, Multifrequency, Active and Passive Microwave Observations

    NASA Technical Reports Server (NTRS)

    Grecu, Mircea; Anagnostou, Emmanouil N.; Olson, William S.; Starr, David OC. (Technical Monitor)

    2002-01-01

    In this study, a technique for estimating vertical profiles of precipitation from multifrequency, multiresolution active and passive microwave observations is investigated using both simulated and airborne data. The technique is applicable to the Tropical Rainfall Measuring Mission (TRMM) satellite multi-frequency active and passive observations. These observations are characterized by various spatial and sampling resolutions. This makes the retrieval problem mathematically more difficult and ill-determined because the quality of information decreases with decreasing resolution. A model that, given reflectivity profiles and a small set of parameters (including the cloud water content, the intercept drop size distribution, and a variable describing the frozen hydrometeor properties), simulates high-resolution brightness temperatures is used. The high-resolution simulated brightness temperatures are convolved at the real sensor resolution. An optimal estimation procedure is used to minimize the differences between simulated and observed brightness temperatures. The retrieval technique is investigated using cloud model synthetic and airborne data from the Fourth Convection And Moisture Experiment. Simulated high-resolution brightness temperatures and reflectivities and airborne observation strong are convolved at the resolution of the TRMM instruments and retrievals are performed and analyzed relative to the reference data used in observations synthesis. An illustration of the possible use of the technique in satellite rainfall estimation is presented through an application to TRMM data. The study suggests improvements in combined active and passive retrievals even when the instruments resolutions are significantly different. Future work needs to better quantify the retrievals performance, especially in connection with satellite applications, and the uncertainty of the models used in retrieval.

  5. Preparation of Granular Red Mud Adsorbent using Different Binders by Microwave Pore - Making and Activation Method

    NASA Astrophysics Data System (ADS)

    Le, Thiquynhxuan; Wang, Hanrui; Ju, Shaohua; Peng, Jinhui; Zhou, Liexing; Wang, Shixing; Yin, Shaohua; Liu, Chao

    2016-04-01

    In this work, microwave energy is used for preparing a granular red mud (GRM) adsorbent made of red mud with different binders, such as starch, sodium silicate and cement. The effects of the preparation parameters, such as binder type, binder addition ratio, microwave heating temperature, microwave power and holding time, on the absorption property of GRM are investigated. The BET surface area, strength, pore structure, XRD and SEM of the GRM absorbent are analyzed. The results show that the microwave roasting has a good effect on pore-making of GRM, especially when using organic binder. Both the BET surface area and the strength of GRM obtained by microwave heating are significantly higher than that by conventional heating. The optimum conditions are obtained as follows: 6:100 (w/w) of starch to red mud ratio, microwave roasting with a power of 2.6 kW at 500℃ for holding time of 30 min. The BET surface area, pore volume and average pore diameter of GRM prepared at the optimum conditions are 15.58 m2/g, 0.0337 cm3/g and 3.1693 A0, respectively.

  6. Using Airborne Microwave Remotely Sensed Root-Zone Soil Moisture and Flux Measurements to Improve Regional Predictions of Carbon Fluxes in a Terrestrial Biosphere Model

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Antonarakis, A. S.; Medvigy, D.; Burgin, M. S.; Crow, W. T.; Milak, S.; Jaruwatanadilok, S.; Truong-Loi, M.; Moghaddam, M.; Saatchi, S. S.; Cuenca, R. H.; Moorcroft, P. R.

    2013-12-01

    North American ecosystems are critical components of the global carbon cycle, exchanging large amounts of carbon dioxide and other gases with the atmosphere. Net ecosystem exchange (NEE) of CO2 between atmosphere and ecosystems quantifies these carbon fluxes, but current continental-scale estimates contain high levels of uncertainty. Root-zone soil moisture (RZSM) and its spatial and temporal heterogeneity influences NEE and improved estimates can help reduce uncertainty in NEE estimates. We used the RZSM measurements from the Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) mission, and the carbon, water and energy fluxes observed by the eddy-covariance flux towers to constrain the Ecosystem Demography Model 2.2 (ED2.2) to improve its predictions of carbon fluxes. The parameters of the ED2.2 model were first optimized at seven flux tower sites in North America, which represent six different biomes, by constraining the model against a suite of flux measurements and forest inventory measurements through a Bayesian Markov-Chain Monte Carlo framework. We further applied the AirMOSS RZSM products to constrain the ED2.2 model to achieve better estimates of regional NEE. Evaluation against flux tower measurements and forest dynamics measurements shows that the constrained ED2.2 model produces improved predictions of monthly to annual carbon fluxes. The remote sensing based RZSM can further help improve the spatial patterns and temporal variations of model NEE. The results demonstrate that model-data fusion can substantially improve model performance and highlight the important role of RZSM in regulating the spatial and temporal heterogeneities of carbon fluxes.

  7. Snow depth retrieval algorithm of saline-alkali land in the western Jilin Province of China using passive microwave remote sensing data

    NASA Astrophysics Data System (ADS)

    Sun, Mingbo; Gu, Lingjia; Ren, Ruizhi; Fu, Haoyang

    2015-09-01

    The western region of Jilin Province is an important part of fragile ecological environment in Northeast China where the soil salinization problem is particularly obvious. Meanwhile, it belongs to a typical snow-covered area and has a northerly continental monsoon climate, with long, cold winters and short, warm summers. It has one single large snowfall period of six month. Therefore, in this paper, the western Jilin Province was selected as the study area and divided into five land surface types including water bodies, grassland, farmland, slight saline-alkali land, moderate and severe saline-alkali land. Furthermore, the two snow depth retrieval algorithms of Chang algorithm and FY3B operational retrieval algorithm were validated and analyzed by using FY-3B/MWRI passive microwave remote sensing data. The main research focused on the analysis of the snow depth covered on the other four different land surface types except water bodies. Based on the five years' observation data from 2011 to 2015, the changes of snow depth on the four land surface types were analyzed and compared with that of MODIS 09A1 snow cover data. The analysis results demonstrated that the snow depth in farmland type is greater than that in grassland type. In addition, the snow depth in slight saline-alkali land type is greater than that in the moderate and severe saline-alkali land type. The study results also showed that the snow depth of Chang's algorithm is more accurate than that of FY3B operational retrieval algorithm in the study area. This research provided important information to the research of snow depth in saline-alkali land area.

  8. Microwave applications range from under the soil to the stratosphere

    NASA Astrophysics Data System (ADS)

    Bierman, Howard

    1990-11-01

    While the current cutback in defense spending had a negative impact on the microwave industry, microwave technology is now being applied to improve mankind's health, to clean up the environment, and provide more food. The paper concentrates on solutions for traffic jams and collision avoidance, the application of microwave hyperthermia to detect and destroy cancer cells, applications for controlling ozone-layer depletion, for investigating iceberg activity and ocean-current patterns in the Arctic, and for measuring soil-moisture content to improve crop efficiency. An experimental 60-GHz communication system for maintaining contact with up to 30 vehicles is described, along with dielectric-loaded lens and multimicrostrip hyperthermia applicators, and microwave equipment for NASA's upper-atmosphere research satellite and ESA's remote-sensing satellite. Stripline techniques to monitor process control on semiconductor wafer and paper production lines are also outlined.

  9. Microwave accelerated synthesis of zinc oxide nanoplates and their enhanced photocatalytic activity under UV and solar illuminations

    NASA Astrophysics Data System (ADS)

    Anas, S.; Rahul, S.; Babitha, K. B.; Mangalaraja, R. V.; Ananthakumar, S.

    2015-11-01

    Photoactive zinc based nanoplates were developed through a rapid microwave synthesis. A low temperature thermolysis reaction in a surfactant medium was initially performed for producing microwave active zinc based polar precursors. Using these precursors, the zinc oxide nanopowder having platelet morphologies were prepared. The nanoplatelets exhibited random growth with non-polar (1 0 1) surface as the major growth plane. The structural and functional features of the resultant zinc oxide samples were monitored using XRD, FTIR, TEM and PL. The photocatalytic activities of the samples were investigated through the standard photoreduction kinetics using the methylene blue dye. The catalytic efficiencies of the samples were checked both under UV and sunlight. A comparative study was also performed with the standard TiO2 sample. The analyses revealed that the microwave derived zinc oxide have higher catalytic efficiency, than the standard titania samples, both under UV and sunlight illuminations. The unique nature of the zinc oxide non-polar surfaces can be attributed due to the presence of more active two dimensional open surfaces and the higher content of oxygen defect concentrations.

  10. The apparent quorum-sensing inhibitory activity of pyrogallol is a side effect of peroxide production.

    PubMed

    Defoirdt, Tom; Pande, Gde Sasmita Julyantoro; Baruah, Kartik; Bossier, Peter

    2013-06-01

    There currently is more and more interest in the use of natural products, such as tea polyphenols, as therapeutic agents. The polyphenol compound pyrogallol has been reported before to inhibit quorum-sensing-regulated bioluminescence in Vibrio harveyi. Here, we report that the addition of 10 mg · liter(-1) pyrogallol protects both brine shrimp (Artemia franciscana) and giant river prawn (Macrobrachium rosenbergii) larvae from pathogenic Vibrio harveyi, whereas the compound showed relatively low toxicity (therapeutic index of 10). We further demonstrate that the apparent quorum-sensing-disrupting activity is a side effect of the peroxide-producing activity of this compound rather than true quorum-sensing inhibition. Our results emphasize that verification of minor toxic effects by using sensitive methods and the use of appropriate controls are essential when characterizing compounds as being able to disrupt quorum sensing. PMID:23545532

  11. Aircraft remote sensing of soil moisture and hydrologic parameters, Taylor Creek, Florida, and Little River, Georgia, 1979 data report

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Schmugge, T. J.; Allen, L. H., Jr.; Oneill, P.; Slack, R.; Wang, J.; Engman, E. T.

    1981-01-01

    Experiments were conducted to evaluate aircraft remote sensing techniques for hydrology in a wide range of physiographic and climatic regions using several sensor platforms. The data were collected in late 1978 and during 1979 in two humid areas--Taylor Creek, Fla., and Little River, Ga. Soil moisture measurements and climatic observations are presented as well as the remote sensing data collected using thermal infrared, passive microwave, and active microwave systems.

  12. Microwave-assisted Synthesis and antifungal activity of coumarin[8,7-e][1,3]oxazine derivatives.

    PubMed

    Zhang, Ming-Zhi; Zhang, Rong-Rong; Yin, Wen-Zheng; Yu, Xiang; Zhang, Ya-Ling; Liu, Pin; Gu, Yu-Cheng; Zhang, Wei-Hua

    2016-08-01

    The synthesis of novel coumarin[8,7-e][1,3]oxazine derivatives through a microwave-assisted three-component one-pot Mannich reaction is described in this study. All the target compounds were evaluated in vitro for their antifungal activity against Botrytis cinerea, Colletotrichum capsici, Alternaria solani, Gibberella zeae, Rhizoctonia solani, and Alternaria mali. The preliminary bioassays showed that 5e, 5m, and 5s exhibited good antifungal activity and the most active compound was 5m with an [Formula: see text] value as low as 2.1 nM against Botrytis cinerea. PMID:26880591

  13. Identifying the Influence of Variable Ice Types on Passive and Active Microwave Measurements for the Purpose of SWE Retrieval

    NASA Astrophysics Data System (ADS)

    Gunn, G. E.; Duguay, C. R.; Derksen, C.

    2010-12-01

    Dual polarized airborne passive microwave (PM) brightness temperatures (Tbs) at 6.9, 19 and 37 GHz H/V and satellite X-band (9.65 GHz VV/VH) active microwave backscatter measurements were combined with coincident in-situ measurements of snow and ice characteristics to determine the potential of unique emission/interaction caused by variable ice properties. Algorithms designed to estimate snow water equivalent (SWE) using the common brightness temperature difference approach (37GHz - 19 GHz) continually underestimate in-situ levels when applied to pure-ice pixels in the Canadian subarctic. Ice thickness measurements were positively correlated with 19 GHz vertically polarised (V pol) passive microwave emissions (R= 0.67), and negatively with 19 GHz horizontally polarised (H pol) emissions (R = -0.79), indicating that surface conditions at the ice/snow interface affect the emissivity at H pol. This study examines the effect of ice types on coincident passive and active microwave measurements for free-floating ice in two lakes (Sitidgi, Husky Lakes). Ice types are delineated using the SAR segmentation program MAGIC (MAp Guided Ice Classification) that has previously been used to characterize sea ice types. Based on output ice types produced by MAGIC, the relationship between active and passive microwave measurements is examined. Output ice classes corresponded well to those measured at coincident in-situ sampling sites. Emissions at 19 GHz H and cross-polarised X-band backscatter (9.65 GHz) increase coincident to ice types that exhibit more scattering potential. Clear ice exhibits the lowest return, followed by a transition zone between clear ice and grey ice. Grey ice exhibits higher returns as a result of the inclusion of spherical air bubbles, followed by rafted ice, which exhibits an excess of scattering potential. Concurrently, transects of dual polarized 6.9 and 19 GHz PM Tbs exhibited a positive relationship with cross-polarized active microwave backscatter (VH

  14. All in a Sniff: Olfaction as a Model for Active Sensing

    PubMed Central

    Wachowiak, Matt

    2011-01-01

    Summary Sensation is an active process involving the selective sampling and central processing of external stimuli in space and time. Olfaction in particular depends strongly on active sensing due to the fact that - at least in mammals - inhalation of air into the nasal cavity is required for odor detection. This seemingly simple first step in odor sensation profoundly shapes nearly all aspects of olfactory system function, from the distribution of odorant receptors to the functional organization of central processing to the perception of odors. The dependence of olfaction on inhalation also allows for profound modulation of olfactory processing by changes in odor sampling strategies in coordination with attentional state and sensory demands. This review discusses the role of active sensing in shaping olfactory system function at multiple levels and draws parallels with other sensory modalities to highlight the importance of an active sensing perspective in understanding how sensory systems work in the behaving animal. PMID:21943596

  15. Assessment of Anti-Quorum Sensing Activity for Some Ornamental and Medicinal Plants Native to Egypt

    PubMed Central

    Zaki, Ahmed A.; Shaaban, Mona I.; Hashish, Nadia E.; Amer, Mohamed A.; Lahloub, Mohamed-Farid

    2013-01-01

    This study investigated the effects of some plant extracts on the bacterial communication system, expressed as quorum sensing (QS) activity. Quorum sensing has a directly proportional effect on the amount of certain compounds, such as pigments, produced by the bacteria. Alcohol extracts of 23 ornamental and medicinal plants were tested for anti-QS activity by the Chromobacterium violaceum assay using the agar cup diffusion method. The screening revealed the anti-QS activity of six plants; namely the leaves of Adhatoda vasica Nees, Bauhinia purpurea L., Lantana camara L., Myoporum laetum G. Forst.; the fruits of Piper longum L.; and the aerial parts of Taraxacum officinale F.H. Wigg. PMID:23641343

  16. Remote sensing of Earth terrain

    NASA Technical Reports Server (NTRS)

    Kong, J. A.

    1992-01-01

    Research findings are summarized for projects dealing with the following: application of theoretical models to active and passive remote sensing of saline ice; radiative transfer theory for polarimetric remote sensing of pine forest; scattering of electromagnetic waves from a dense medium consisting of correlated Mie scatterers with size distribution and applications to dry snow; variance of phase fluctuations of waves propagating through a random medium; theoretical modeling for passive microwave remote sensing of earth terrain; polarimetric signatures of a canopy of dielectric cylinders based on first and second order vector radiative transfer theory; branching model for vegetation; polarimetric passive remote sensing of periodic surfaces; composite volume and surface scattering model; and radar image classification.

  17. Improving the biogas production performance of municipal waste activated sludge via disperser induced microwave disintegration.

    PubMed

    Kavitha, S; Rajesh Banu, J; Vinoth Kumar, J; Rajkumar, M

    2016-10-01

    In this study, the influence of disperser induced microwave pretreatment was investigated to analyze the proficiency of floc disruption on subsequent disintegration and biodegradability process. Initially, the flocs in the sludge was disrupted through disperser at a specific energy input of 25.3kJ/kgTS. The upshot of the microwave disintegration presents that the solids reduction and solubilization of floc disrupted (disperser induced microwave pretreated) sludge was found to be 17.33% and 22% relatively greater than that achieved in microwave pretreated (9.3% and 16%) sludge alone. The biodegradability analysis, affords an evaluation of parameter confidence and correlation determination. The eventual biodegradability of microwave pretreated, and floc disrupted sludges were computed to be 0.15(gCOD/gCOD) and 0.28(gCOD/gCOD), respectively. An economic assessment of this study offers a positive net profit of about 104.8USD/ton of sludge in floc disrupted sample. PMID:26897472

  18. A self-sensing active magnetic bearing based on a direct current measurement approach.

    PubMed

    Niemann, Andries C; van Schoor, George; du Rand, Carel P

    2013-01-01

    Active magnetic bearings (AMBs) have become a key technology in various industrial applications. Self-sensing AMBs provide an integrated sensorless solution for position estimation, consolidating the sensing and actuating functions into a single electromagnetic transducer. The approach aims to reduce possible hardware failure points, production costs, and system complexity. Despite these advantages, self-sensing methods must address various technical challenges to maximize the performance thereof. This paper presents the direct current measurement (DCM) approach for self-sensing AMBs, denoting the direct measurement of the current ripple component. In AMB systems, switching power amplifiers (PAs) modulate the rotor position information onto the current waveform. Demodulation self-sensing techniques then use bandpass and lowpass filters to estimate the rotor position from the voltage and current signals. However, the additional phase-shift introduced by these filters results in lower stability margins. The DCM approach utilizes a novel PA switching method that directly measures the current ripple to obtain duty-cycle invariant position estimates. Demodulation filters are largely excluded to minimize additional phase-shift in the position estimates. Basic functionality and performance of the proposed self-sensing approach are demonstrated via a transient simulation model as well as a high current (10 A) experimental system. A digital implementation of amplitude modulation self-sensing serves as a comparative estimator. PMID:24030681

  19. A Self-Sensing Active Magnetic Bearing Based on a Direct Current Measurement Approach

    PubMed Central

    Niemann, Andries C.; van Schoor, George; du Rand, Carel P.

    2013-01-01

    Active magnetic bearings (AMBs) have become a key technology in various industrial applications. Self-sensing AMBs provide an integrated sensorless solution for position estimation, consolidating the sensing and actuating functions into a single electromagnetic transducer. The approach aims to reduce possible hardware failure points, production costs, and system complexity. Despite these advantages, self-sensing methods must address various technical challenges to maximize the performance thereof. This paper presents the direct current measurement (DCM) approach for self-sensing AMBs, denoting the direct measurement of the current ripple component. In AMB systems, switching power amplifiers (PAs) modulate the rotor position information onto the current waveform. Demodulation self-sensing techniques then use bandpass and lowpass filters to estimate the rotor position from the voltage and current signals. However, the additional phase-shift introduced by these filters results in lower stability margins. The DCM approach utilizes a novel PA switching method that directly measures the current ripple to obtain duty-cycle invariant position estimates. Demodulation filters are largely excluded to minimize additional phase-shift in the position estimates. Basic functionality and performance of the proposed self-sensing approach are demonstrated via a transient simulation model as well as a high current (10 A) experimental system. A digital implementation of amplitude modulation self-sensing serves as a comparative estimator. PMID:24030681

  20. Characteristics of active spectral sensor for plant sensing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant stress has been estimated by spectral signature using both passive and active sensors. As optical sensors measure reflected light from a target, changes in illumination conditions critically affect sensor response. Active spectral sensors minimize the illumination effects by producing their ...

  1. Microwave ECR Ion Thruster Development Activities at NASA Glenn Research Center

    NASA Technical Reports Server (NTRS)

    Foster, John E.; Patterson, Michael J.

    2002-01-01

    Outer solar system missions will have propulsion system lifetime requirements well in excess of that which can be satisfied by ion thrusters utilizing conventional hollow cathode technology. To satisfy such mission requirements, other technologies must be investigated. One possible approach is to utilize electrodeless plasma production schemes. Such an approach has seen low power application less than 1 kW on earth-space spacecraft such as ARTEMIS which uses the rf thruster the RIT 10 and deep space missions such as MUSES-C which will use a microwave ion thruster. Microwave and rf thruster technologies are compared. A microwave-based ion thruster is investigated for potential high power ion thruster systems requiring very long lifetimes.

  2. Active regulation of receptor ratios controls integration of quorum-sensing signals in Vibrio harveyi

    PubMed Central

    Teng, Shu-Wen; Schaffer, Jessica N; Tu, Kimberly C; Mehta, Pankaj; Lu, Wenyun; Ong, N P; Bassler, Bonnie L; Wingreen, Ned S

    2011-01-01

    Quorum sensing is a chemical signaling mechanism used by bacteria to communicate and orchestrate group behaviors. Multiple feedback loops exist in the quorum-sensing circuit of the model bacterium Vibrio harveyi. Using fluorescence microscopy of individual cells, we assayed the activity of the quorum-sensing circuit, with a focus on defining the functions of the feedback loops. We quantitatively investigated the signaling input–output relation both in cells with all feedback loops present as well as in mutants with specific feedback loops disrupted. We found that one of the feedback loops regulates receptor ratios to control the integration of multiple signals. Together, the feedback loops affect the input–output dynamic range of signal transmission and the noise in the output. We conclude that V. harveyi employs multiple feedback loops to simultaneously control quorum-sensing signal integration and to ensure signal transmission fidelity. PMID:21613980

  3. Advantages and Limitations in using Active Remote Sensing Technology for Disaster Damage Assessment

    NASA Astrophysics Data System (ADS)

    Tauhidur Rahman, Muhammad

    2013-04-01

    Following any major natural or man-made disaster, rapid monitoring and assessment of infrastructures and environmental damages are essential for successful rescue and relief operations. While pre- and post-disaster data from passive remote sensing imageries have played a major role in assessing damages on a damage/no damage basis for over four decades, latest advances in active remote sensing technologies such as Radar and Lidar are also becoming quite useful. The goal of this paper is to first explain the basic theories and analytical techniques involved in using active remote sensing data for assessing damages following a major natural disaster. It will then discuss some of the advantages and limitations often faced by researchers and disaster management personnel when using data from these sensors. Finally, it will highlight how data from Lidar and other active sensors were used to assess damages from three recent major disasters.

  4. Zinc activates damage-sensing TRPA1 ion channels

    PubMed Central

    Hu, Hongzhen; Bandell, Michael; Petrus, Matt J.; Zhu, Michael X.; Patapoutian, Ardem

    2009-01-01

    Zinc is an essential biological trace element. It is required for the structure or function of over 300 proteins, and is increasingly recognized for its role in cell signaling. However, high concentrations of zinc have cytotoxic effects, and overexposure to zinc can cause pain and inflammation through unknown mechanisms. Here we show that zinc excites nociceptive somatosensory neurons and causes nociception in mice through TRPA1, a cation channel previously shown to mediate the pungency of wasabi and cinnamon through cysteine-modification. Zinc activates TRPA1 through a novel mechanism that requires zinc influx through TRPA1 channels and subsequent activation via specific intracellular cysteine and histidine residues. TRPA1 is highly sensitive to intracellular zinc, as low nanomolar concentrations activate TRPA1 and modulate its sensitivity. These findings identify TRPA1 as a major target for the sensory effects of zinc, and support an emerging role for zinc as a signaling molecule that can modulate sensory transmission. PMID:19202543

  5. Microwave-Assisted Simultaneous Extraction of Luteolin and Apigenin from Tree Peony Pod and Evaluation of Its Antioxidant Activity

    PubMed Central

    Wang, Hongzheng; Yang, Lei; Zu, Yuangang; Zhao, Xiuhua

    2014-01-01

    An efficient microwave-assisted extraction (MAE) technique was employed in simultaneous extraction of luteolin and apigenin from tree peony pod. The MAE procedure was optimized using response surface methodology (RSM) and compared with other conventional extraction techniques of macerate extraction (ME) and heat reflux extraction (HRE). The optimal conditions of MAE were as follows: employing 70% ethanol volume fraction as solvent, soaking time of 4 h, liquid-solid ratio of 10 (mL/g), microwave irradiation power of 265 W, microwave irradiation time of 9.6 min, and 3 extraction cycles. Under the optimal conditions, 151 μg/g luteolin and 104 μg/g apigenin were extracted from the tree peony pod. Compared with ME and HRE, MAE gave the highest extraction efficiency. The antioxidant activities of the extracts obtained by MAE, ME, and HRE were evaluated using a 2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) free radical-scavenging assay, a ferric reducing antioxidant power assay (FRAP), and a reducing power assay. Meanwhile, the structural changes of the unprocessed and processed tree peony pod samples were analyzed by scanning electron microscopy. PMID:25405227

  6. Activities of the US Geological Survey in Applications of Remote Sensing in the Chesapeake Bay Region

    NASA Technical Reports Server (NTRS)

    Wray, J. R.

    1978-01-01

    The application of remote sensing in the Chesapeake Bay region has been a central concern of three project activities of the U.S. Geological Survey: two are developmental, and one is operational. The two developmental activities were experiments in land-use and land-cover inventory and change detection using remotely sensed data from aircraft and from the LANDSAT and Skylab satellites. One of these is CARETS (Central Atlantic Regional Ecological Test Site). The other developmental task is the Census Cities Experiment in Urban Change Detection. The present major concern is an operational land-use and land-cover data-analysis program, including a supporting geographical information system.

  7. Making Sense of Total VET Activity: An Initial Market Analysis

    ERIC Educational Resources Information Center

    National Centre for Vocational Education Research (NCVER), 2016

    2016-01-01

    Following the successful first national publication of total vocational education and training (VET) activity and presentation of various informative data products, NCVER has continued to undertake further analysis of the submitted data. This paper is the first in a suite of the National Centre for Vocational Education Research (NCVER) authored…

  8. Making Sense of Participation in Cultural Activities for Children

    ERIC Educational Resources Information Center

    Hultgren, Frances; Johansson, Barbro

    2013-01-01

    Introduction: This paper investigates participatory practices in library activities for young children and their care-givers in a specific cultural context. Method: Using an ethnographic approach data were collected through participant observations of songtimes for babies and toddlers, and interviews and group interviews with staff and…

  9. Changes of antioxidant activity and formation of 5-hydroxymethylfurfural in honey during thermal and microwave processing.

    PubMed

    Kowalski, Stanisław

    2013-11-15

    The paper presents the results of microwave irradiation and conventional heating of honey. These two kinds of thermal treatment result in the formation of 5-hydroxymethyl-2-furfural (HMF), and changes in the antioxidant potential of honeys, which were studied as well. Four types of honey (honeydew, lime, acacia, buckwheat) were analyzed. Honey samples were subjected to conventional heating in a water bath (WB) at 90°C up to 60min or to the action of a microwave field (MW) with constant power of 1.26W/g of the sample up to 6min. Changes in the antioxidant capacity of honeys were measured as a percentage of free radical (ABTS(+)and DPPH) scavenging ability. Changes in the total polyphenols content (TPC) (equivalents of gallic acid mg/100g of honey) were also determined. Formation of HMF in honey treated with a microwave field was faster in comparison with the conventional process. Changes in the antioxidant properties of honey subjected to thermal or microwave processing might have been botanical origin dependent. PMID:23790927

  10. Retrieval of spinach crop parameters by microwave remote sensing with back propagation artificial neural networks: A comparison of different transfer functions

    NASA Astrophysics Data System (ADS)

    Prasad, Rajendra; Pandey, A.; Singh, K. P.; Singh, V. P.; Mishra, R. K.; Singh, D.

    2012-08-01

    Back propagation artificial natural network (BPANN) is a well known and widely used machine learning methodology in the field of remote sensing. In this paper an attempt is made to retrieve the spinach crop parameters like biomass, leaf area index, average plant height and soil moisture content by using the X-band scattering coefficients with BPANN at different growth stages of this crop. The maturity age of this crop was found to be 45 days from the date of sowing. After 45 days from the date of sowing, this crop was cut at a certain height for production. Then, it is a point of interest to investigate the microwave response of variation in production. Significant variations in all the crop parameters were observed after cutting the crop and consequently made the problem more critical. Our work confirms the utility of BPANN in handling such a non-linear data set. The BPANN is essentially a network of simple processing nodes arranged into different layers as input, hidden and the output. The input layer propagates components of a particular input vector after weighting these with synaptic weights to each node in the hidden layer. At each node, these weighted input vector components are added. Each hidden layer computes output corresponding to these weighted sum through a non-linear/linear function (e.g. LOGSIG, TANSIG and PURLIN). These functions are known as transfer functions. Thus, each of the hidden layer nodes compute output values, which become inputs to the nodes of the output layer. At nodes of output layer also a weighted sum of outputs of previous layer (hidden layer) are obtained and processed through a transfer function. Thus, the output layer nodes compute the network output for the particular input vector. In this paper, output nodes use linear transfer function. Different transfer functions e.g. TANSIG, LOGSIG and PURELIN were used and the performance of the ANN was optimized by changing the number of neurons in the hidden layers. The present

  11. The effects of vegetation and soil hydraulic properties on passive microwave sensing of soil moisture: Data report for the 1982 fiels experiments

    NASA Technical Reports Server (NTRS)

    Oneill, P.; Jackson, T.; Blanchard, B. J.; Vandenhoek, R.; Gould, W.; Wang, J.; Glazar, W.; Mcmurtrey, J., III

    1983-01-01

    Field experiments to (1) study the biomass and geometrical structure properties of vegetation canopies to determine their impact on microwave emission data, and (2) to verify whether time series microwave data can be related to soil hydrologic properties for use in soil type classification. Truck mounted radiometers at 1.4 GHz and 5 GHz were used to obtain microwave brightness temperatures of bare vegetated test plots under different conditions of soil wetness, plant water content and canopy structure. Observations of soil moisture, soil temperature, vegetation biomass and other soil and canopy parameters were made concurrently with the microwave measurements. The experimental design and data collection procedures for both experiments are documented and the reduced data are presented in tabular form.

  12. Botswana water and surface energy balance research program. Part 2: Large scale moisture and passive microwaves

    NASA Technical Reports Server (NTRS)

    Vandegriend, A. A.; Owe, M.; Chang, A. T. C.

    1992-01-01

    The Botswana water and surface energy balance research program was developed to study and evaluate the integrated use of multispectral satellite remote sensing for monitoring the hydrological status of the Earth's surface. The research program consisted of two major, mutually related components: a surface energy balance modeling component, built around an extensive field campaign; and a passive microwave research component which consisted of a retrospective study of large scale moisture conditions and Nimbus scanning multichannel microwave radiometer microwave signatures. The integrated approach of both components are explained in general and activities performed within the passive microwave research component are summarized. The microwave theory is discussed taking into account: soil dielectric constant, emissivity, soil roughness effects, vegetation effects, optical depth, single scattering albedo, and wavelength effects. The study site is described. The soil moisture data and its processing are considered. The relation between observed large scale soil moisture and normalized brightness temperatures is discussed. Vegetation characteristics and inverse modeling of soil emissivity is considered.

  13. Remote sensing and image interpretation

    NASA Technical Reports Server (NTRS)

    Lillesand, T. M.; Kiefer, R. W. (Principal Investigator)

    1979-01-01

    A textbook prepared primarily for use in introductory courses in remote sensing is presented. Topics covered include concepts and foundations of remote sensing; elements of photographic systems; introduction to airphoto interpretation; airphoto interpretation for terrain evaluation; photogrammetry; radiometric characteristics of aerial photographs; aerial thermography; multispectral scanning and spectral pattern recognition; microwave sensing; and remote sensing from space.

  14. Does Active Learning through an Antisense Jigsaw Make Sense?

    NASA Astrophysics Data System (ADS)

    Seetharaman, Mahadevan; Musier-Forsyth, Karin

    2003-12-01

    Three journal articles on nucleic acid antisense modification strategies were assigned to 12 students as part of an active learning "jigsaw" exercise for a graduate-level chemistry course on nucleic acids. Each student was required to read one of the three articles. This assignment was preceded by an hour-long lecture on the basic concepts in antisense antigene technology. On the day of the jigsaw, the students with the same article (three groups of four students) discussed their article briefly, and then formed four new groups where no one had read the same article. Each student spent about five minutes teaching his or her article to the other group members, using specific questions provided to guide the discussion. This exercise laid the foundation for bringing the discussion to the entire class, where most of the students actively participated. To test the students' comprehension of the reading materials, a problem set was designed that required not only an understanding of the three articles, but also application of the concepts learned. The effectiveness of this active learning strategy and its applicability to other topics are discussed in this article.

  15. Active sensing associated with spatial learning reveals memory-based attention in an electric fish.

    PubMed

    Jun, James J; Longtin, André; Maler, Leonard

    2016-05-01

    Active sensing behaviors reveal what an animal is attending to and how it changes with learning. Gymnotus sp, a gymnotiform weakly electric fish, generates an electric organ discharge (EOD) as discrete pulses to actively sense its surroundings. We monitored freely behaving gymnotid fish in a large dark "maze" and extracted their trajectories and EOD pulse pattern and rate while they learned to find food with electrically detectable landmarks as cues. After training, they more rapidly found food using shorter, more stereotyped trajectories and spent more time near the food location. We observed three forms of active sensing: sustained high EOD rates per unit distance (sampling density), transient large increases in EOD rate (E-scans) and stereotyped scanning movements (B-scans) were initially strong at landmarks and food, but, after learning, intensified only at the food location. During probe (no food) trials, after learning, the fish's search area and intense active sampling was still centered on the missing food location, but now also increased near landmarks. We hypothesize that active sensing is a behavioral manifestation of attention and essential for spatial learning; the fish use spatial memory of landmarks and path integration to reach the expected food location and confine their attention to this region. PMID:26961107

  16. Characterization of Deep Tunneling Activity through Remote-Sensing Techniques

    SciTech Connect

    R. G. Best, P. J. Etzler, and J. D. Bloom

    1997-10-01

    This work is a case study demonstrating the uses of multispectral and multi-temporal imagery to characterize deep tunneling activity. A drainage tunnel excavation in Quincy, MA is the case locality. Data used are aerial photographs (digitized) and Daedalus 3600 MSS image data that were collected in July and October of 1994. Analysis of the data includes thermal characterization, spectral characterization, multi-temporal analysis, and volume estimation using digital DEM generation. The results demonstrate the type of information that could be generated by multispectral, multi-temporal data if the study locality were a clandestine excavation site with restricted surface access.

  17. Dielectric elastomer vibrissal system for active tactile sensing

    NASA Astrophysics Data System (ADS)

    Conn, Andrew T.; Pearson, Martin J.; Pipe, Anthony G.; Welsby, Jason; Rossiter, Jonathan

    2012-04-01

    Rodents are able to dexterously navigate confined and unlit environments by extracting spatial and textural information with their whiskers (or vibrissae). Vibrissal-based active touch is suited to a variety of applications where vision is occluded, such as search-and-rescue operations in collapsed buildings. In this paper, a compact dielectric elastomer vibrissal system (DEVS) is described that mimics the vibrissal follicle-sinus complex (FSC) found in rodents. Like the vibrissal FSC, the DEVS encapsulates all sensitive mechanoreceptors at the root of a passive whisker within an antagonistic muscular system. Typically, rats actively whisk arrays of macro-vibrissae with amplitudes of up to +/-25°. It is demonstrated that these properties can be replicated by exploiting the characteristic large actuation strains and passive compliance of dielectric elastomers. A prototype DEVS is developed using VHB 4905 and embedded strain gauges bonded to the root of a tapered whisker. The DEVS is demonstrated to produce a maximum rotational output of +/-22.8°. An electro-mechanical model of the DEVS is derived, which incorporates a hyperelastic material model and Euler- Bernoulli beam equations. The model is shown to predict experimental measurements of whisking stroke amplitude and whisker deflection.

  18. Passive and active EO sensing of small surface vessels

    NASA Astrophysics Data System (ADS)

    Steinvall, Ove; Berglund, Folke; Allard, Lars; Öhgren, Johan; Larsson, Hâkan; Amselem, Elias; Gustafsson, Frank; Repasi, Endre; Lutzmann, Peter; Göhler, Benjamin; Hammer, Marcus; McEwen, Kennedy; McEwan, Ken

    2015-10-01

    The detection and classification of small surface targets at long ranges is a growing need for naval security. This paper will present an overview of a measurement campaign which took place in the Baltic Sea in November 2014. The purpose was to test active and passive EO sensors (10 different types) for the detection, tracking and identification of small sea targets. The passive sensors were covering the visual, SWIR, MWIR and LWIR regions. Active sensors operating at 1.5 μm collected data in 1D, 2D and 3D modes. Supplementary sensors included a weather station, a scintillometer, as well as sensors for positioning and attitude determination of the boats. Three boats in the class 4-9 meters were used as targets. After registration of the boats at close range they were sent out to 5-7 km distance from the sensor site. At the different ranges the target boats were directed to have different aspect angles relative to the direction of observation. Staff from IOSB Fraunhofer in Germany and from Selex (through DSTL) in UK took part in the tests beside FOI who was arranging the trials. A summary of the trial and examples of data and imagery will be presented.

  19. Interactive Change Detection Using High Resolution Remote Sensing Images Based on Active Learning with Gaussian Processes

    NASA Astrophysics Data System (ADS)

    Ru, Hui; Yu, Huai; Huang, Pingping; Yang, Wen

    2016-06-01

    Although there have been many studies for change detection, the effective and efficient use of high resolution remote sensing images is still a problem. Conventional supervised methods need lots of annotations to classify the land cover categories and detect their changes. Besides, the training set in supervised methods often has lots of redundant samples without any essential information. In this study, we present a method for interactive change detection using high resolution remote sensing images with active learning to overcome the shortages of existing remote sensing image change detection techniques. In our method, there is no annotation of actual land cover category at the beginning. First, we find a certain number of the most representative objects in unsupervised way. Then, we can detect the change areas from multi-temporal high resolution remote sensing images by active learning with Gaussian processes in an interactive way gradually until the detection results do not change notably. The artificial labelling can be reduced substantially, and a desirable detection result can be obtained in a few iterations. The experiments on Geo-Eye1 and WorldView2 remote sensing images demonstrate the effectiveness and efficiency of our proposed method.

  20. Active and Passive Sensing from Geosynchronous and Libration Orbits

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark; Raymond, Carol; Hildebrand, Peter

    2003-01-01

    The development of the LEO (EOS) missions has led the way to new technologies and new science discoveries. However, LEO measurements alone cannot cost effectively produce high time resolution measurements needed to move the science to the next level. Both GEO and the Lagrange points, L1 and L2, provide vantage points that will allow higher time resolution measurements. GEO is currently being exploited by weather satellites, but the sensors currently operating at GEO do not provide the spatial or spectral resolution needed for atmospheric trace gas, ocean or land surface measurements. It is also may be possible to place active sensors in geostationary orbit. It seems clear, that the next era in earth observation and discovery will be opened by sensor systems operating beyond near earth orbit.

  1. Active Teaching Strategies for a Sense of Salience: End-of-Life Communication

    ERIC Educational Resources Information Center

    Kopp, Mary L.

    2013-01-01

    This study compared active teaching strategies with passive lecture by evaluating cognitive, affective, and psychomotor learning outcomes, while highlighting end-of-life communication in nursing education. The problem addressed was twofold: First, passive lecture prevents transfer to situational decision-making, or a sense of salience (Benner,…

  2. More than Activities: Using a "Sense of Place" to Enrich Student Experience in Adventure Sport

    ERIC Educational Resources Information Center

    Leather, Mark; Nicholls, Fiona

    2016-01-01

    There has been increasing interest in recent years in the significance of a sense of place in the literature of outdoor adventure education. In the UK relationships between outdoor education and the environment still appear largely focused on the science of the natural environment and the activity in question. In this paper, we present empirical…

  3. Molten salt-supported polycondensation of optically active diacid monomers with an aromatic thiazole-bearing diamine using microwave irradiation

    PubMed Central

    Mallakpour, Shadpour; Zadehnazari, Amin

    2013-01-01

    Microwave heating was used to prepare optically active thiazole-bearing poly(amide-imide)s. Polymerization reactions were carried out in the molten tetrabutylammonium bromide as a green molten salt medium and triphenyl phosphite as the homogenizer. Structural elucidation of the compounds was performed by Fourier transform infrared and NMR spectroscopic data and elemental analysis results. The polymeric samples were readily soluble in various organic solvents, forming low-colored and flexible thin films via solution casting. They showed high thermal stability with decomposition temperature being above 360 °C. They were assembled randomly in a nanoscale size. PMID:25685498

  4. Soil Active Layer Freeze/Thaw Detection Using Combined L- and P-Band Radar Remote Sensing

    NASA Astrophysics Data System (ADS)

    Du, J.; Kimball, J. S.; Moghaddam, M.

    2014-12-01

    Monitoring of soil active layer freeze-thaw (FT) dynamics is critical for studying high-latitude ecosystem and environmental changes. We evaluated the potential of inferring FT state dynamics within a tundra soil profile using combined L- and P-band radar remote sensing and forward radiative transfer modeling of backscatter characteristics. A first-order two-layer soil scattering model (FTSS) was developed in this study to analyze soil multi-layer scattering effects. The FTSS was evaluated against other sophisticated modeling approaches and showed comparable performance. The FTSS was then applied to analyzing L- and P-band microwave responses to layered soil. We find that soil volume scattering is rather weak for the two frequencies for frozen or dry soil with mean particle size below 10mm diameter. Dielectric contrast between adjacent soil layers can contribute to total backscatter at both L- and P-band with more significant impact on P-band than L-band signals depending on the depth of soil profile. Combined L- and P-band radar data are shown to have greater utility than single channel observations in detecting soil FT dynamics and dielectric profile inhomogeneity. Further analysis using available airborne synthetic aperture radar (SAR) data and in-situ measurements also confirm that soil profile heterogeneity can be effectively detected using combined L- and P-band radar backscatter data. This study demonstrates the potential of lower frequency SARs from airborne missions, including UAV-SAR and AirMOSS, for Arctic and alpine assessment of soil active layer properties.

  5. Models to support active sensing of biological aerosol clouds

    NASA Astrophysics Data System (ADS)

    Brown, Andrea M.; Kalter, Jeffrey M.; Corson, Elizabeth C.; Chaudhry, Zahra; Boggs, Nathan T.; Brown, David M.; Thomas, Michael E.; Carter, Christopher C.

    2013-05-01

    Elastic backscatter LIght Detection And Ranging (LIDAR) is a promising approach for stand-off detection of biological aerosol clouds. Comprehensive models that explain the scattering behavior from the aerosol cloud are needed to understand and predict the scattering signatures of biological aerosols under varying atmospheric conditions and against different aerosol backgrounds. Elastic signatures are dependent on many parameters of the aerosol cloud, with two major components being the size distribution and refractive index of the aerosols. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) has been in a unique position to measure the size distributions of released biological simulant clouds using a wide assortment of aerosol characterization systems that are available on the commercial market. In conjunction with the size distribution measurements, JHU/APL has also been making a dedicated effort to properly measure the refractive indices of the released materials using a thin-film absorption technique and laboratory characterization of the released materials. Intimate knowledge of the size distributions and refractive indices of the biological aerosols provides JHU/APL with powerful tools to build elastic scattering models, with the purpose of understanding, and ultimately, predicting the active signatures of biological clouds.

  6. Microbial growth and quorum sensing antagonist activities of herbal plants extracts.

    PubMed

    Al-Hussaini, Reema; Mahasneh, Adel M

    2009-01-01

    Antimicrobial and antiquorum sensing (AQS) activities of fourteen ethanolic extracts of different parts of eight plants were screened against four Gram-positive, five Gram-negative bacteria and four fungi. Depending on the plant part extract used and the test microorganism, variable activities were recorded at 3 mg per disc. Among the Grampositive bacteria tested, for example, activities of Laurus nobilis bark extract ranged between a 9.5 mm inhibition zone against Bacillus subtilis up to a 25 mm one against methicillin resistant Staphylococcus aureus. Staphylococcus aureus and Aspergillus fumigatus were the most susceptible among bacteria and fungi tested towards other plant parts. Of interest is the tangible antifungal activity of a Tecoma capensis flower extract, which is reported for the first time. However, minimum inhibitory concentrations (MIC's) for both bacteria and fungi were relatively high (0.5-3.0 mg). As for antiquorum sensing activity against Chromobacterium violaceum, superior activity (>17 mm QS inhibition) was associated with Sonchus oleraceus and Laurus nobilis extracts and weak to good activity (8-17 mm) was recorded for other plants. In conclusion, results indicate the potential of these plant extracts in treating microbial infections through cell growth inhibition or quorum sensing antagonism, which is reported for the first time, thus validating their medicinal use. PMID:19783935

  7. Impacts of microwave pretreatments on the semi-continuous anaerobic digestion of dairy waste activated sludge

    SciTech Connect

    Uma Rani, R.; Adish Kumar, S.; Kaliappan, S.; Yeom, IckTae; Rajesh Banu, J.

    2013-05-15

    Highlights: ► Microwave pretreatment of dairy WAS was studied. ► MW pretreatment at 70% intensity for 12 min, COD solubilization was 18.6%. ► Biogas production and SS reduction was 35% and 14% higher than control. ► In digester at 15 days SRT with medium OLR, SS and VS reduction was 67% and 64%. ► Biogas and methane production was 57% and 49% higher than control, in digesters. - Abstract: Microwave (MW) irradiation is one of the new and possible methods used for pretreating the sludge. Following its use in different fields, this MW irradiation method has proved to be more appropriate in the field of environmental research. In this paper, we focused on the effects of MW irradiation at different intensities on solubilization, biodegradation and anaerobic digestion of sludge from the dairy sludge. The changes in the soluble fractions of the organic matter, the biogas yield, the methane content in the biogas were used as control parameters for evaluating the efficiency of the MW pretreatment. Additionally, the energetic efficiency was also examined. In terms of an energetic aspect, the most economical pretreatment of sludge was at 70% intensity for 12 min irradiation time. At this, COD solubilization, SS reduction and biogas production were found to be 18.6%, 14% and 35% higher than the control, respectively. Not only the increase in biogas production was investigated, excluding protein and carbohydrate hydrolysis was also performed successfully by this microwave pretreatment even at low irradiation energy input. Also, experiments were carried out in semi continuous anaerobic digesters, with 3.5 L working volume. Combining microwave pretreatment with anaerobic digestion led to 67%, 64% and 57% of SS reduction, VS reduction and biogas production higher than the control, respectively.

  8. Microwave quantum illumination.

    PubMed

    Barzanjeh, Shabir; Guha, Saikat; Weedbrook, Christian; Vitali, David; Shapiro, Jeffrey H; Pirandola, Stefano

    2015-02-27

    Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here, we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or quantum radar, is shown to be superior to that of any classical microwave radar of equal transmitted energy. PMID:25768743

  9. Microwave-activated nanodroplet vaporization for highly efficient tumor ablation with real-time monitoring performance.

    PubMed

    Xu, Jinshun; Chen, Yu; Deng, Liming; Liu, Jianxin; Cao, Yang; Li, Pan; Ran, Haitao; Zheng, Yuanyi; Wang, Zhigang

    2016-11-01

    The fast development of nanotechnology has provided a new efficient strategy for enhancing the therapeutic efficiency of various treatment modalities against cancer. However, the improvement of minimally invasive microwave therapy based on nanomaterials has not been realized. In this work, we successfully designed and synthesized a novel folate-targeted nanodroplet (TPN) with a composite mixture of perfluorocarbons as the core and lipid as the shell, which exerts the distinctive dual functions as the adjuvant for highly efficient percutaneous ultrasound imaging-guided microwave ablation (MWA) of tumors. Based on the unique phase-changeable performance of TPN nanosystem, a novel microwave-droplet vaporization (MWDV) strategy was proposed, for the first time, to overcome the critical issues of traditional acoustic-droplet vaporization (ADV) and optical-droplet vaporization (ODV) for cancer theranostics. Especially, the elaborately designed TPN can overcome the challenges of indistinct imaging of ablation margin and the limited ablation zone of MWA modality against cancer. The high efficiency of this new MWDV strategy has been systematically elucidated in vitro, ex vivo and in vivo. Therefore, such a successful demonstration of the role of nanomaterials (TPN in this case) in ultrasound imaging-guided MWA therapy against cancer provides a highly feasible strategy to effectively enhance the MWA outcome with the specific features of high efficiency and biosafety. PMID:27573134

  10. Microwave Ovens

    MedlinePlus

    ... Required Reports for the Microwave Oven Manufacturers or Industry Exemption from Certain Reporting and Recordkeeping Requirements for ... Microwave Ovens (PDF) (PDF - 2.5MB) FDA eSubmitter Industry Guidance - Documents of Interest Notifications to Industry (PDF ...

  11. Activities of Asian Students and Young Scientists on Photogrammetry and Remote Sensing

    NASA Astrophysics Data System (ADS)

    Miyazaki, H.; Lo, C.-Y.; Cho, K.

    2012-07-01

    This paper reports a history and future prospects of the activities by Asian students and young scientists on photogrammetry and remote sensing. For future growths of academic fields, active communications among students and young scientists are indispensable. In some countries and regions in Asia, local communities are already established by youths and playing important roles of building networks among various schools and institutes. The networks are expected to evolve innovative cooperations after the youths achieve their professions. Although local communities are getting solid growth, Asian youths had had little opportunities to make contacts with youths of other countries and regions. To promote youth activities among Asian regions, in 2007, Asian Association on Remote Sensing (AARS) started a series of programs involving students and young scientists within the annual conferences, the Asian Conference on Remote Sensing (ACRS). The programs have provided opportunities and motivations to create networks among students and young scientists. As a result of the achievements, the number of youth interested and involved in the programs is on growing. In addition, through the events held in Asian region by ISPRS Student Consortium (ISPRSSC) and WG VI/5, the Asian youths have built friendly partnership with ISPRSSC. Currently, many Asian youth are keeping contacts with ACRS friends via internet even when they are away from ACRS. To keep and expand the network, they are planning to establish an Asian youth organization on remote sensing. This paper describes about the proposals and future prospects on the Asian youth organization.

  12. Microwave Oven Observations.

    ERIC Educational Resources Information Center

    Sumrall, William J.; Richardson, Denise; Yan, Yuan

    1998-01-01

    Explains a series of laboratory activities which employ a microwave oven to help students understand word problems that relate to states of matter, collect data, and calculate and compare electrical costs to heat energy costs. (DDR)

  13. The world mountain Damavand: documentation and monitoring of human activities using remote sensing data

    NASA Astrophysics Data System (ADS)

    Kostka, Robert

    The use of different remote sensing data is demonstrated by example of the world mountain, Mt. Damavand (5671 m) in the Alborz Mountains, Iran. Several types of satellite data were required to master the complex task of preparing a monograph of this mountain: SSEOP images of NASA, Russian KFA-1000 pictures, CORONA panoramic images of NASA and Russian KVR-1000 orthoimages. Examples of climatic studies, transportation routes, water resources, conservation areas and relicts of human land-use are presented in order to show the potential of remote sensing data. The right choice of image data is a top priority in applied remote sensing in order to obtain significant results in the documentation and monitoring of human activities.

  14. Investigation of remote sensing techniques of measuring soil moisture

    NASA Technical Reports Server (NTRS)

    Newton, R. W. (Principal Investigator); Blanchard, A. J.; Nieber, J. L.; Lascano, R.; Tsang, L.; Vanbavel, C. H. M.

    1981-01-01

    Major activities described include development and evaluation of theoretical models that describe both active and passive microwave sensing of soil moisture, the evaluation of these models for their applicability, the execution of a controlled field experiment during which passive microwave measurements were acquired to validate these models, and evaluation of previously acquired aircraft microwave measurements. The development of a root zone soil water and soil temperature profile model and the calibration and evaluation of gamma ray attenuation probes for measuring soil moisture profiles are considered. The analysis of spatial variability of soil information as related to remote sensing is discussed as well as the implementation of an instrumented field site for acquisition of soil moisture and meteorologic information for use in validating the soil water profile and soil temperature profile models.

  15. Structural sensing of interior sound for active control of noise in structural-acoustic cavities.

    PubMed

    Bagha, Ashok K; Modak, S V

    2015-07-01

    This paper proposes a method for structural sensing of acoustic potential energy for active control of noise in a structural-acoustic cavity. The sensing strategy aims at global control and works with a fewer number of sensors. It is based on the established concept of radiation modes and hence does not add too many states to the order of the system. Acoustic potential energy is sensed using a combination of a Kalman filter and a frequency weighting filter with the structural response measurements as the inputs. The use of Kalman filter also makes the system robust against measurement noise. The formulation of the strategy is presented using finite element models of the system including that of sensors and actuators so that it can be easily applied to practical systems. The sensing strategy is numerically evaluated in the framework of Linear Quadratic Gaussian based feedback control of interior noise in a rectangular box cavity with a flexible plate with single and multiple pairs of piezoelectric sensor-actuator patches when broadband disturbances act on the plate. The performance is compared with an "acoustic filter" that models the complete transfer function from the structure to the acoustic domain. The sensing performance is also compared with a direct estimation strategy. PMID:26233001

  16. Remote sensing of atmospheric water vapor, liquid water and wind speed at the ocean surface by passive microwave techniques from the Nimbus-5 satellite

    NASA Technical Reports Server (NTRS)

    Chang, A. T. C.; Wilheit, T. T.

    1977-01-01

    The microwave brightness temperature measurements for Nimbus-5 electrically scanned microwave radiometer and Nimbus E microwave spectrometer are used to retrieve the atmospheric water vapor, liquid water and wind speed by a quasi-statistical retrieval technique. It is shown that the brightness temperature can be utilized to yield these parameters under various weather conditions. Observations at 19.35 GHz, 22.235 GHz and 31.4 GHz were input to the regression equations. The retrieved values of these parameters for portions of two Nimbus-5 orbits are presented. Then comparison between the retrieved parameters and the available observations on the total water vapor content and the surface wind speed are made. The estimated errors for retrieval are approximately 0.15 g/sq cm for water vapor content, 6.5 mg/sq cm for liquid water content and 6.6 m/sec for surface wind speed.

  17. Passive Microwave Radiometry of Land:Contributions of Tom Schmugge and Anatoli Shutko

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent advances and the state of the art of land surface remote sensing using passive microwave techniques owes its heritage to the contributions of Tom Schmugge and Anatolij Shutko over the last 30 years. These contributions cover a range of activities including fundamental theory, controlled condi...

  18. Evaluation of a Modified SEBAL Algorithm to Estimate Actual Evapotranspiration in Cotton Ecosystems of Central Asia using Microwave and Optical Remote Sensing Data

    NASA Astrophysics Data System (ADS)

    Knoefel, Patrick; Conrad, Christopher

    2015-04-01

    Being recognized as an essential component of both the water and the energy cycle, actual evapotranspiration (ETa) plays in important role in order to describe the complex interactions within the climate system of the Earth. Here, remote sensing is a powerful tool to estimate regional ETa to support the regional water management. For instance, the water withdrawal of the agricultural sector in OECD countries is on average about 44 %, but in the states of Central Asia it achieves more than 90 %. This fact is identified as one of the main reasons for the increasing water scarcity in this region. An accuracy assessment of the methods used for determining ETa is necessary concerning an appropriate use of the model results to support agriculture and irrigation management. Within Central Asia the Khorezm region in Uzbekistan is a case study region for the problems of irrigated agriculture. For Khorezm the seasonal ETa based on MODIS data was calculated for the years 2009 - 2011 using a partly modified surface energy balance algorithm for land (SEBAL). SEBAL was implemented based on MODIS time series to calculate the energy balance components like net radiation (Rn), sensible heat (H), latent heat (LE), and soil heat flux (G). Whilst SEBAL is using an empirical equation for the estimation of G, a more physically based method was introduced in this study. This method uses microwave soil moisture products (ASAR and ASCAT-SSM) as an additional model input. The input parameters and the model results of all energy balance components (Rn, H, LE, and G) were intensively validated by field measurements with an eddy covariance system and soil sensors. The model shows very good performance for Rn with average model efficiency (NSE) of 0.68 and small relative errors (rRMSE) of about 10%. For turbulent heat fluxes good results can be achieved with NSE of 0.31 for H and 0.55 for LE, the rRMSE are about 21% (H) and 18% (LE). Soil heat flux estimation could be improved using the

  19. On the haptic nature of the active electric sense of fish.

    PubMed

    Caputi, Angel A; Aguilera, Pedro A; Carolina Pereira, Ana; Rodríguez-Cattáneo, Alejo

    2013-11-01

    Electroreception is a sensory modality present in chondrichthyes, actinopterygii, amphibians, and mammalian monotremes. The study of this non-intuitive sensory modality has provided insights for better understanding of sensory systems in general and inspired the development of innovative artificial devices. Here we review evidence obtained from the analysis of electrosensory images, neurophysiological data from the recording of unitary activity in the electrosensory lobe, and psychophysical data from analysis of novelty responses provoked in well-defined stimulus conditions, which all confirm that active electroreception has a short range, and that the influence of exploratory movements on object identification is strong. In active electric images two components can be identified: a "global" image profile depending on the volume, shape and global impedance of an object and a "texture" component depending on its surface attributes. There is a short range of the active electric sense and the progressive "blurring" of object image with distance. Consequently, the lack of precision regarding object location, considered together, challenge the current view of this sense as serving long range electrolocation and the commonly used metaphor of "electric vision". In fact, the active electric sense shares more commonalities with human active touch than with teleceptive senses as vision or audition. Taking into account that other skin exteroceptors and proprioception may be congruently stimulated during fish exploratory movements we propose that electric, mechanoceptive and proprioceptive sensory modalities found in electric fish could be considered together as a single haptic sensory system. This article is part of a Special Issue entitled Neural Coding 2012. PMID:23727613

  20. Total synthesis of protosappanin A and its derivatives via palladium catalyzed ortho C-H activation/C-C cyclization under microwave irradiation.

    PubMed

    Liu, Jiaqi; Zhou, Xuan; Wang, Chenglong; Fu, Wanyong; Chu, Wenyi; Sun, Zhizhong

    2016-04-14

    A total synthesis method for protosappanin A, which is a complex natural product with many biological activities, was developed with 6 linear steps. Dibenzo[b,d]oxepinones as the key intermediates of the synthetic route were prepared by a palladium-catalyzed ortho C-H activation/C-C cyclization under microwave irradiation. 25 derivatives of protosappanin A were obtained. PMID:26997503