WorldWideScience

Sample records for surface reflectance calibration

  1. Early Evaluation of the VIIRS Calibration, Cloud Mask and Surface Reflectance Earth Data Records

    Science.gov (United States)

    Vermote, Eric; Justice, Chris; Csiszar, Ivan

    2014-01-01

    Surface reflectance is one of the key products fromVIIRS and as withMODIS, is used in developing several higherorder land products. The VIIRS Surface Reflectance (SR) Intermediate Product (IP) is based on the heritageMODIS Collection 5 product (Vermote, El Saleous, & Justice, 2002). The quality and character of surface reflectance depend on the accuracy of the VIIRS Cloud Mask (VCM), the aerosol algorithms and the adequate calibration of the sensor. The focus of this paper is the early evaluation of the VIIRS SR product in the context of the maturity of the operational processing system, the Interface Data Processing System (IDPS). After a brief introduction, the paper presents the calibration performance and the role of the surface reflectance in calibration monitoring. The analysis of the performance of the cloud mask with a focus on vegetation monitoring (no snow conditions) shows typical problems over bright surfaces and high elevation sites. Also discussed is the performance of the aerosol input used in the atmospheric correction and in particular the artifacts generated by the use of the Navy Aerosol Analysis and Prediction System. Early quantitative results of the performance of the SR product over the AERONET sites showthatwith the fewadjustments recommended, the accuracy iswithin the threshold specifications. The analysis of the adequacy of the SR product (Land PEATE adjusted version) in applications of societal benefits is then presented. We conclude with a set of recommendations to ensure consistency and continuity of the JPSS mission with the MODIS Land Climate Data Record.

  2. Impact of MODIS Sensor Calibration Updates on Greenland Ice Sheet Surface Reflectance and Albedo Trends

    Science.gov (United States)

    Casey, Kimberly A.; Polashenski, Chris M.; Chen, Justin; Tedesco, Marco

    2017-01-01

    We evaluate Greenland Ice Sheet (GrIS) surface reflectance and albedo trends using the newly released Collection 6 (C6) MODIS (Moderate Resolution Imaging Spectroradiometer) products over the period 2001-2016. We find that the correction of MODIS sensor degradation provided in the new C6 data products reduces the magnitude of the surface reflectance and albedo decline trends obtained from previous MODIS data (i.e., Collection 5, C5). Collection 5 and 6 data product analysis over GrIS is characterized by surface (i.e., wet vs. dry) and elevation (i.e., 500-2000 m, 2000 m and greater) conditions over the summer season from 1 June to 31 August. Notably, the visible-wavelength declining reflectance trends identified in several bands of MODIS C5 data from previous studies are only slightly detected at reduced magnitude in the C6 versions over the dry snow area. Declining albedo in the wet snow and ice area remains over the MODIS record in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analyses of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to Greenland Ice Sheet albedo change. Investigators using MODIS data for other ocean, atmosphere and/or land analyses are urged to consider similar re-examinations of trends previously established using C5 data.

  3. Impact of MODIS sensor calibration updates on Greenland Ice Sheet surface reflectance and albedo trends

    Science.gov (United States)

    Casey, Kimberly A.; Polashenski, Chris M.; Chen, Justin; Tedesco, Marco

    2017-08-01

    We evaluate Greenland Ice Sheet (GrIS) surface reflectance and albedo trends using the newly released Collection 6 (C6) MODIS (Moderate Resolution Imaging Spectroradiometer) products over the period 2001-2016. We find that the correction of MODIS sensor degradation provided in the new C6 data products reduces the magnitude of the surface reflectance and albedo decline trends obtained from previous MODIS data (i.e., Collection 5, C5). Collection 5 and 6 data product analysis over GrIS is characterized by surface (i.e., wet vs. dry) and elevation (i.e., 500-2000 m, 2000 m and greater) conditions over the summer season from 1 June to 31 August. Notably, the visible-wavelength declining reflectance trends identified in several bands of MODIS C5 data from previous studies are only slightly detected at reduced magnitude in the C6 versions over the dry snow area. Declining albedo in the wet snow and ice area remains over the MODIS record in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analyses of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to Greenland Ice Sheet albedo change. Investigators using MODIS data for other ocean, atmosphere and/or land analyses are urged to consider similar re-examinations of trends previously established using C5 data.

  4. Impact of MODIS sensor calibration updates on Greenland Ice Sheet surface reflectance and albedo trends

    Directory of Open Access Journals (Sweden)

    K. A. Casey

    2017-08-01

    Full Text Available We evaluate Greenland Ice Sheet (GrIS surface reflectance and albedo trends using the newly released Collection 6 (C6 MODIS (Moderate Resolution Imaging Spectroradiometer products over the period 2001–2016. We find that the correction of MODIS sensor degradation provided in the new C6 data products reduces the magnitude of the surface reflectance and albedo decline trends obtained from previous MODIS data (i.e., Collection 5, C5. Collection 5 and 6 data product analysis over GrIS is characterized by surface (i.e., wet vs. dry and elevation (i.e., 500–2000 m, 2000 m and greater conditions over the summer season from 1 June to 31 August. Notably, the visible-wavelength declining reflectance trends identified in several bands of MODIS C5 data from previous studies are only slightly detected at reduced magnitude in the C6 versions over the dry snow area. Declining albedo in the wet snow and ice area remains over the MODIS record in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analyses of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to Greenland Ice Sheet albedo change. Investigators using MODIS data for other ocean, atmosphere and/or land analyses are urged to consider similar re-examinations of trends previously established using C5 data.

  5. Quantitative surface topography determination by Nomarski reflection microscopy. 2: Microscope modification, calibration, and planar sample experiments

    International Nuclear Information System (INIS)

    Hartman, J.S.; Gordon, R.L.; Lessor, D.L.

    1980-01-01

    The application of reflective Nomarski differential interference contrast microscopy for the determination of quantitative sample topography data is presented. The discussion includes a review of key theoretical results presented previously plus the experimental implementation of the concepts using a commercial Momarski microscope. The experimental work included the modification and characterization of a commercial microscope to allow its use for obtaining quantitative sample topography data. System usage for the measurement of slopes on flat planar samples is also discussed. The discussion has been designed to provide the theoretical basis, a physical insight, and a cookbook procedure for implementation to allow these results to be of value to both those interested in the microscope theory and its practical usage in the metallography laboratory

  6. Synchrotron radiation based micro X-ray fluorescence analysis of the calibration samples used in surface sensitive total reflection and grazing emission X-ray fluorescence techniques

    Science.gov (United States)

    Kubala-Kukuś, A.; Banaś, D.; Pajek, M.; Szlachetko, J.; Jagodziński, P.; Susini, J.; Salomé, M.

    2013-12-01

    Total reflection X-ray fluorescence (TXRF) and grazing emission X-ray fluorescence (GEXRF) are surface sensitive techniques and can be used for detailed surface studies of different materials, including ultra-low concentration contamination or the lateral and depth distributions of elements. The calibration procedure typically used involves placing a micro-droplet (˜μl) of the standard solution onto a silicon wafer (or quartz backing). After evaporation of the solvent, the residual amount of elements is used as a reference standard. Knowledge of the distribution of residue material on the substrate surface is crucial for precise quantification. In the present work the investigation of the lateral distribution of elements in the multielemental calibrating samples, containing the 23 most commonly studied elements, by using the synchrotron radiation based micro X-ray fluorescence is presented. The goal of this project was the study of a uniformity of the elemental distributions and determination of the residual elements morphology depending on the temperature of the drying process. The X-ray images were compared with optical and SEM images. Paper presents in details the experimental setup, sample preparation procedures, measurements and results. In the analysis of the X-ray images of the sample dried in high temperature the censoring approach was applied improving the quality of statistical analysis. The information on the elements distribution in the calibrating samples can be useful for developing more accurate calibration procedures applied in quantitative analysis of surface sensitive TXRF and GEXRF techniques.

  7. Cross-calibration of Medium Resolution Earth Observing Satellites by Using EO-1 Hyperion-derived Spectral Surface Reflectance from "Lunar Cal Sites"

    Science.gov (United States)

    Ungar, S.

    2017-12-01

    Over the past 3 years, the Earth Observing-one (EO-1) Hyperion imaging spectrometer was used to slowly scan the lunar surface at a rate which results in up to 32X oversampling to effectively increase the SNR. Several strategies, including comparison against the USGS RObotic Lunar Observatory (ROLO) mode,l are being employed to estimate the absolute and relative accuracy of the measurement set. There is an existing need to resolve discrepancies as high as 10% between ROLO and solar based calibration of current NASA EOS assets. Although the EO-1 mission was decommissioned at the end of March 2017, the development of a well-characterized exoatmospheric spectral radiometric database, for a range of lunar phase angles surrounding the fully illuminated moon, continues. Initial studies include a comprehensive analysis of the existing 17-year collection of more than 200 monthly lunar acquisitions. Specific lunar surface areas, such as a lunar mare, are being characterized as potential "lunar calibration sites" in terms of their radiometric stability in the presence of lunar nutation and libration. Site specific Hyperion-derived lunar spectral reflectance are being compared against spectrographic measurements made during the Apollo program. Techniques developed through this activity can be employed by future high-quality orbiting imaging spectrometers (such as HyspIRI and EnMap) to further refine calibration accuracies. These techniques will enable the consistent cross calibration of existing and future earth observing systems (spectral and multi-spectral) including those that do not have lunar viewing capability. When direct lunar viewing is not an option for an earth observing asset, orbiting imaging spectrometers can serve as transfer radiometers relating that asset's sensor response to lunar values through near contemporaneous observations of well characterized stable CEOS test sites. Analysis of this dataset will lead to the development of strategies to ensure more

  8. Fringe-reflection photogrammetry based on poses calibration with planar mirror reflection

    Science.gov (United States)

    Xiao, Yong-Liang; Zhong, Jianxin; Zhang, Qican; Su, Xianyu; You, Zhisheng

    2017-10-01

    Since liquid crystal display (LCD) screen locates outside of the camera's field of view in fringe-reflection photogrammetry, fringes displayed on LCD screen are obtained through specular reflection by a fixed camera. Thus, the pose calibration between camera and LCD screen is one of the main challenges in fringe-reflection photogrammetry. A markerless planar mirror is used to reflect the LCD screen more than three times, and the fringes are mapped into the fixed camera. The geometrical calibration can be accomplished by estimating the pose between the camera and virtual image of fringes. With the help of the relation between their pose, incidence and reflection ray can be unified in the camera frame, forward triangulation intersection can be operated in the camera frame to measure 3D coordinate of specular surface. In the final optimization, constraint bundle adjustment is operated to refine simultaneously the camera intrinsic parameters including distortion coefficients, estimated geometrical pose between LCD screen and camera, 3D coordinate of specular surface, with the help of absolute phase collinear constraint. Results of simulations and experiments demonstrate that the pose calibration with planar mirror reflection is simple, feasible and constraint bundle adjustment can enhance the three-dimensional coordinate measurement accuracy in fringe-reflection photogrammetry.

  9. Spectral emissivity of surface blackbody calibrators

    DEFF Research Database (Denmark)

    Clausen, Sønnik

    2007-01-01

    in emissivity using similar materials can be reduced to 0.5-1% by optimizing the coating process and the surface geometry. Results are discussed and an equation for calculation of the equivalent blackbody surface temperature from FTIR spectra is presented, including reflected ambient radiation. It is in most......The normal spectral emissivity of commercial infrared calibrators is compared with measurements of anodized aluminum samples and grooved aluminum surfaces coated with Pyromark. Measurements performed by FTIR spectroscopy in the wavelength interval from 2 to 20 mu m and at temperatures between 5...... and 550 degrees C are presented with absolute uncertainties from 0.25% to 1% in spectral regions with sufficient signal and no significant atmospheric gas absorption. A large variation in emissivity with wavelength is observed for some surfaces, i.e., from 1% to 3% to more than 10%. The variation...

  10. Calibration of alpha surface contamination monitor

    International Nuclear Information System (INIS)

    Freitas, I.S.M. de; Goncalez, O.L.

    1990-01-01

    In this work, the results, as well as the methodology, of the calibration of an alpha surface contamination monitor are presented. The calibration factors are obtained by least-squares fitting with effective variance. (author)

  11. Test surfaces useful for calibration of surface profilometers

    Science.gov (United States)

    Yashchuk, Valeriy V; McKinney, Wayne R; Takacs, Peter Z

    2013-12-31

    The present invention provides for test surfaces and methods for calibration of surface profilometers, including interferometric and atomic force microscopes. Calibration is performed using a specially designed test surface, or the Binary Pseudo-random (BPR) grating (array). Utilizing the BPR grating (array) to measure the power spectral density (PSD) spectrum, the profilometer is calibrated by determining the instrumental modulation transfer.

  12. Suomi NPP VIIRS Reflective Solar Bands Operational Calibration Reprocessing

    Directory of Open Access Journals (Sweden)

    Slawomir Blonski

    2015-12-01

    Full Text Available Radiometric calibration coefficients for the VIIRS (Visible Infrared Imaging Radiometer Suite reflective solar bands have been reprocessed from the beginning of the Suomi NPP (National Polar-orbiting Partnership mission until present. An automated calibration procedure, implemented in the NOAA (National Oceanic and Atmospheric Administration JPSS (Joint Polar Satellite System operational data production system, was applied to reprocess onboard solar calibration data and solar diffuser degradation measurements. The latest processing parameters from the operational system were used to include corrected solar vectors, optimized directional dependence of attenuation screens transmittance and solar diffuser reflectance, updated prelaunch calibration coefficients without an offset term, and optimized Robust Holt-Winters filter parameters. The parameters were consistently used to generate a complete set of the radiometric calibration coefficients for the entire duration of the Suomi NPP mission. The reprocessing has demonstrated that the automated calibration procedure can be successfully applied to all solar measurements acquired from the beginning of the mission until the full deployment of the automated procedure in the operational processing system. The reprocessed calibration coefficients can be further used to reprocess VIIRS SDR (Sensor Data Record and other data products. The reprocessing has also demonstrated how the automated calibration procedure can be used during activation of the VIIRS instruments on the future JPSS satellites.

  13. Calibration of areal surface topography measuring instruments

    Science.gov (United States)

    Seewig, J.; Eifler, M.

    2017-06-01

    The ISO standards which are related to the calibration of areal surface topography measuring instruments are the ISO 25178-6xx series which defines the relevant metrological characteristics for the calibration of different measuring principles and the ISO 25178-7xx series which defines the actual calibration procedures. As the field of areal measurement is however not yet fully standardized, there are still open questions to be addressed which are subject to current research. Based on this, selected research results of the authors in this area are presented. This includes the design and fabrication of areal material measures. For this topic, two examples are presented with the direct laser writing of a stepless material measure for the calibration of the height axis which is based on the Abbott- Curve and the manufacturing of a Siemens star for the determination of the lateral resolution limit. Based on these results, as well a new definition for the resolution criterion, the small scale fidelity, which is still under discussion, is presented. Additionally, a software solution for automated calibration procedures is outlined.

  14. Intercomparison of Approaches to the Empirical Line Method for Vicarious Hyperspectral Reflectance Calibration

    Directory of Open Access Journals (Sweden)

    Joseph D. Ortiz

    2017-09-01

    Full Text Available Analysis of visible remote sensing data research requires removing atmospheric effects by conversion from radiance to at-surface reflectance. This conversion can be achieved through theoretical radiative transfer models, which yield good results when well-constrained by field observations, although these measurements are often lacking. Additionally, radiative transfer models often perform poorly in marine or lacustrine settings or when complex air masses with variable aerosols are present. The empirical line method (ELM measures reference targets of known reflectance in the scene. ELM methods require minimal environmental observations and are conceptually simple. However, calibration coefficients are unique to the image containing the reflectance reference. Here we compare the conversion of hyperspectral radiance observations obtained with the NASA Glenn Research Center Hyperspectral Imager to at-surface reflectance factor using two reflectance reference targets. The first target employs spherical convex mirrors, deployed on the water surface to reflect ambient direct solar and hemispherical sky irradiance to the sensor. We calculate the mirror gain using near concurrent at-sensor reflectance, integrated mirror radiance, and in situ water reflectance. The second target is the Lambertian-like blacktop surface at Maumee Bay State Park, Oregon, OH, where reflectance was measured concurrently by a downward looking, spectroradiometer on the ground, the aerial hyperspectral imager and an upward looking spectroradiometer on the aircraft. These methods allows us to produce an independently calibrated at-surface water reflectance spectrum, when atmospheric conditions are consistent. We compare the mirror and blacktop-corrected spectra to the in situ water reflectance, and find good agreement between methods. The blacktop method can be applied to all scenes, while the mirror calibration method, based on direct observation of the light illuminating the

  15. Reflective terahertz (THz) imaging: system calibration using hydration phantoms

    Science.gov (United States)

    Bajwa, Neha; Garritano, James; Lee, Yoon Kyung; Tewari, Priyamvada; Sung, Shijun; Maccabi, Ashkan; Nowroozi, Bryan; Babakhanian, Meghedi; Sanghvi, Sajan; Singh, Rahul; Grundfest, Warren; Taylor, Zachary

    2013-02-01

    Terahertz (THz) hydration sensing continues to gain traction in the medical imaging community due to its unparalleled sensitivity to tissue water content. Rapid and accurate detection of fluid shifts following induction of thermal skin burns as well as remote corneal hydration sensing have been previously demonstrated in vivo using reflective, pulsed THz imaging. The hydration contrast sensing capabilities of this technology were recently confirmed in a parallel 7 Tesla Magnetic Resonance (MR) imaging study, in which burn areas are associated with increases in local mobile water content. Successful clinical translation of THz sensing, however, still requires quantitative assessments of system performance measurements, specifically hydration concentration sensitivity, with tissue substitutes. This research aims to calibrate the sensitivity of a novel, reflective THz system to tissue water content through the use of hydration phantoms for quantitative comparisons of THz hydration imagery.Gelatin phantoms were identified as an appropriate tissue-mimicking model for reflective THz applications, and gel composition, comprising mixtures of water and protein, was varied between 83% to 95% hydration, a physiologically relevant range. A comparison of four series of gelatin phantom studies demonstrated a positive linear relationship between THz reflectivity and water concentration, with statistically significant hydration sensitivities (p hydration). The THz-phantom interaction is simulated with a three-layer model using the Transfer Matrix Method with agreement in hydration trends. Having demonstrated the ability to accurately and noninvasively measure water content in tissue equivalent targets with high sensitivity, reflective THz imaging is explored as a potential tool for early detection and intervention of corneal pathologies.

  16. REFLECTANCE CALIBRATION SCHEME FOR AIRBORNE FRAME CAMERA IMAGES

    Directory of Open Access Journals (Sweden)

    U. Beisl

    2012-07-01

    Full Text Available The image quality of photogrammetric images is influenced by various effects from outside the camera. One effect is the scattered light from the atmosphere that lowers contrast in the images and creates a colour shift towards the blue. Another is the changing illumination during the day which results in changing image brightness within an image block. In addition, there is the so-called bidirectional reflectance of the ground (BRDF effects that is giving rise to a view and sun angle dependent brightness gradient in the image itself. To correct for the first two effects an atmospheric correction with reflectance calibration is chosen. The effects have been corrected successfully for ADS linescan sensor data by using a parametrization of the atmospheric quantities. Following Kaufman et al. the actual atmospheric condition is estimated by the brightness of a dark pixel taken from the image. The BRDF effects are corrected using a semi-empirical modelling of the brightness gradient. Both methods are now extended to frame cameras. Linescan sensors have a viewing geometry that is only dependent from the cross track view zenith angle. The difference for frame cameras now is to include the extra dimension of the view azimuth into the modelling. Since both the atmospheric correction and the BRDF correction require a model inversion with the help of image data, a different image sampling strategy is necessary which includes the azimuth angle dependence. For the atmospheric correction a sixth variable is added to the existing five variables visibility, view zenith angle, sun zenith angle, ground altitude, and flight altitude – thus multiplying the number of modelling input combinations for the offline-inversion. The parametrization has to reflect the view azimuth angle dependence. The BRDF model already contains the view azimuth dependence and is combined with a new sampling strategy.

  17. A climatology of visible surface reflectance spectra

    International Nuclear Information System (INIS)

    Zoogman, Peter; Liu, Xiong; Chance, Kelly; Sun, Qingsong; Schaaf, Crystal; Mahr, Tobias; Wagner, Thomas

    2016-01-01

    We present a high spectral resolution climatology of visible surface reflectance as a function of wavelength for use in satellite measurements of ozone and other atmospheric species. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument is planned to measure backscattered solar radiation in the 290–740 nm range, including the ultraviolet and visible Chappuis ozone bands. Observation in the weak Chappuis band takes advantage of the relative transparency of the atmosphere in the visible to achieve sensitivity to near-surface ozone. However, due to the weakness of the ozone absorption features this measurement is more sensitive to errors in visible surface reflectance, which is highly variable. We utilize reflectance measurements of individual plant, man-made, and other surface types to calculate the primary modes of variability of visible surface reflectance at a high spectral resolution, comparable to that of TEMPO (0.6 nm). Using the Moderate-resolution Imaging Spectroradiometer (MODIS) Bidirection Reflectance Distribution Function (BRDF)/albedo product and our derived primary modes we construct a high spatial resolution climatology of wavelength-dependent surface reflectance over all viewing scenes and geometries. The Global Ozone Monitoring Experiment–2 (GOME-2) Lambertian Equivalent Reflectance (LER) product provides complementary information over water and snow scenes. Preliminary results using this approach in multispectral ultraviolet+visible ozone retrievals from the GOME-2 instrument show significant improvement to the fitting residuals over vegetated scenes. - Highlights: • Our goals was visible surface reflectance for satellite trace gas measurements. • Captured the range of surface reflectance spectra through EOF analysis. • Used satellite surface reflectance products for each given scene to anchor EOFs. • Generated a climatology of time/geometry dependent surface reflectance spectra. • Demonstrated potential to

  18. Global Space-Based Inter-Calibration System Reflective Solar Calibration Reference: From Aqua MODIS to S-NPP VIIRS

    Science.gov (United States)

    Xiong, Xiaoxiong; Angal, Amit; Butler, James; Cao, Changyong; Doelling, Daivd; Wu, Aisheng; Wu, Xiangqian

    2016-01-01

    The MODIS has successfully operated on-board the NASA's EOS Terra and Aqua spacecraft for more than 16 and 14 years, respectively. MODIS instrument was designed with stringent calibration requirements and comprehensive on-board calibration capability. In the reflective solar spectral region, Aqua MODIS has performed better than Terra MODIS and, therefore, has been chosen by the Global Space-based Inter-Calibration System (GSICS) operational community as the calibration reference sensor in cross-sensor calibration and calibration inter-comparisons. For the same reason, it has also been used by a number of earth observing sensors as their calibration reference. Considering that Aqua MODIS has already operated for nearly 14 years, it is essential to transfer its calibration to a follow-on reference sensor with a similar calibration capability and stable performance. The VIIRS is a follow-on instrument to MODIS and has many similar design features as MODIS, including their on-board calibrators (OBC). As a result, VIIRS is an ideal candidate to replace MODIS to serve as the future GSICS reference sensor. Since launch, the S-NPP VIIRS has already operated for more than 4 years and its overall performance has been extensively characterized and demonstrated to meet its overall design requirements. This paper provides an overview of Aqua MODIS and S-NPP VIIRS reflective solar bands (RSB) calibration methodologies and strategies, traceability, and their on-orbit performance. It describes and illustrates different methods and approaches that can be used to facilitate the calibration reference transfer, including the use of desert and Antarctic sites, deep convective clouds (DCC), and the lunar observations.

  19. LBA-ECO LC-18 Hyperion 30-m Surface Reflectance, Mato Grosso, Brazil: July 2004

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This image was collected by the Hyperion sensor on 10-July-2004 at 13:16:16 GMT. It was calibrated to apparent surface reflectance using the ACORN...

  20. LBA-ECO LC-18 Hyperion 30-m Surface Reflectance, Mato Grosso, Brazil: July 2004

    Data.gov (United States)

    National Aeronautics and Space Administration — This image was collected by the Hyperion sensor on 10-July-2004 at 13:16:16 GMT. It was calibrated to apparent surface reflectance using the ACORN atmospheric...

  1. A climatology of visible surface reflectance spectra

    Science.gov (United States)

    Zoogman, Peter; Liu, Xiong; Chance, Kelly; Sun, Qingsong; Schaaf, Crystal; Mahr, Tobias; Wagner, Thomas

    2016-09-01

    We present a high spectral resolution climatology of visible surface reflectance as a function of wavelength for use in satellite measurements of ozone and other atmospheric species. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument is planned to measure backscattered solar radiation in the 290-740 nm range, including the ultraviolet and visible Chappuis ozone bands. Observation in the weak Chappuis band takes advantage of the relative transparency of the atmosphere in the visible to achieve sensitivity to near-surface ozone. However, due to the weakness of the ozone absorption features this measurement is more sensitive to errors in visible surface reflectance, which is highly variable. We utilize reflectance measurements of individual plant, man-made, and other surface types to calculate the primary modes of variability of visible surface reflectance at a high spectral resolution, comparable to that of TEMPO (0.6 nm). Using the Moderate-resolution Imaging Spectroradiometer (MODIS) Bidirection Reflectance Distribution Function (BRDF)/albedo product and our derived primary modes we construct a high spatial resolution climatology of wavelength-dependent surface reflectance over all viewing scenes and geometries. The Global Ozone Monitoring Experiment-2 (GOME-2) Lambertian Equivalent Reflectance (LER) product provides complementary information over water and snow scenes. Preliminary results using this approach in multispectral ultraviolet+visible ozone retrievals from the GOME-2 instrument show significant improvement to the fitting residuals over vegetated scenes.

  2. A Bayesian Reflection on Surfaces

    Directory of Open Access Journals (Sweden)

    David R. Wolf

    1999-10-01

    Full Text Available Abstract: The topic of this paper is a novel Bayesian continuous-basis field representation and inference framework. Within this paper several problems are solved: The maximally informative inference of continuous-basis fields, that is where the basis for the field is itself a continuous object and not representable in a finite manner; the tradeoff between accuracy of representation in terms of information learned, and memory or storage capacity in bits; the approximation of probability distributions so that a maximal amount of information about the object being inferred is preserved; an information theoretic justification for multigrid methodology. The maximally informative field inference framework is described in full generality and denoted the Generalized Kalman Filter. The Generalized Kalman Filter allows the update of field knowledge from previous knowledge at any scale, and new data, to new knowledge at any other scale. An application example instance, the inference of continuous surfaces from measurements (for example, camera image data, is presented.

  3. Reflection of Slow Electrons from Solid Surface

    Science.gov (United States)

    Mustafaev, Alexander; Ainov, Matsak; Kaganovich, Igor; Demidov, Vladimir

    2013-09-01

    Given that progress of future plasma technologies depends on control of electron coefficient reflection r0, the development of methods of measurement and control of r0 is of great importance. Published experimental data on r0 for slow electrons are inconsistent and sometime give large values up to r0 ~ 0 , 8 and even higher. This talk presents a technique for r0 measurements in low pressure plasmas in the presence of transverse magnetic field. It is found that for poly-crystal surface, effective reflection coefficient can really reach value of 0.8. It is demonstrated that it is connected to additional reflection from potential barrier near the surfaces. The contribution of electron reflection from the barrier and the surface has been divided and studied. The data have been confirmed at different mono-crystal surfaces. This work was supported by DoE Fusion Energy Sciences contract DE-SC0001939 and Education Ministry of the RF.

  4. Specular Reflection from Rough Surfaces Revisited

    Science.gov (United States)

    Yasuda, Kensei; Kim, Alvin; Cho, Hayley; Timofejev, Timofej; Walecki, Wojciech J.; Klep, James; Edelson, Amy S.; Walecki, Abigail S.; Walecki, Eve S.; Walecki, Peter S.

    2016-01-01

    In his beautiful paper, Hasan Fakhruddin reported observations of mirror-like reflections in the rough surface of a ground glass plate. Similar effects have been recently employed for metrology of the roughness of optical diffusers used in modern light emitting device illumination systems. We report the observations of specular reflection in…

  5. Calibration guidelines for surface texture instruments - horizontal axis

    DEFF Research Database (Denmark)

    Andreasen, Jan Lasson; Shem, R. Krüger

    The present report is a documentation of the work carried out at DTU, on TASK 5.1: PROCEDURES FOR CALIBRATION IN X- AND Y- DIRECTION the project with contract SMT4-CT97-2176 with title: Calibration Standards for Surface Topography Measuring Systems down to Nanometric Scale. After a short introduc...

  6. Simulation Tool for GNSS Ocean Surface Reflections

    OpenAIRE

    Høeg, Per; von Benzon, Hans-Henrik; Durgonics, Tibor

    2015-01-01

    GNSS coherent and incoherent reflected signals have the potential of deriving large scale parameters of ocean surfaces, as barotropic variability, eddy currents and fronts, Rossby waves, coastal upwelling, mean ocean surfaceheights, and patterns of the general ocean circulation. In the reflection zone the measurements may deriveparameters as sea surface roughness, winds, waves, heights and tilts from the spectral measurements. Previous measurements from the top of mountains and airplanes have...

  7. A high-reflective surface measurement method based on conoscopic holography technology

    Science.gov (United States)

    Cheng, Xu; Li, ZhongWei; Shi, YuSheng; Zhao, HengShuang; Zhan, Guomin

    2014-11-01

    Measuring high-reflective surfaces using optical method is always a big challenging problem. This paper presents a high-reflective surface measurement method based on conoscopic holography technology using a 4D motion platform equipped with a conoscopic holography optical probe. There are two key problems needed to solve before the automate scan of the complex shape surface: the coordinate calibration and the path planning. To improve the calibration efficiency and accuracy, the coordinate calibration is divided into two parts: the rough calibration and the accurate registration. The path planning consists of two aspects including: the path points generation and the path points verification. In addition, by scanning the objects having high-reflective surfaces, such as the metal blades, coins and other work-pieces, the efficiency of the measurement method has been verified.

  8. On automatic visual inspection of reflective surfaces

    DEFF Research Database (Denmark)

    Kulmann, Lionel

    1995-01-01

    lighting methods in a framework, general usable for inspecting reflective surfaces. Special attention has been given to the design of illumination techniques to enhance defects of highly reflective aluminum sheets. The chosen optical system setup has been used to enhance surface defects of other reflective......This thesis descrbes different methods to perform automatic visual inspection of reflective manufactured products, with the aim of increasing productivity, reduce cost and improve the quality level of the production. We investigate two different systems performing automatic visual inspection....... The first is the inspection of highly reflective aluminum sheets, used by the Danish company Bang & Olufsen, as a part of the exterior design and general appearance of their audio and video products. The second is the inspection of IBM hard disk read/write heads for defects during manufacturing. We have...

  9. Multitemporal Cross-Calibration of the Terra MODIS and Landsat 7 ETM+ Reflective Solar Bands

    Science.gov (United States)

    Angal, Amit; Xiong, Xiaoxiong; Wu, Aisheng; Changler, Gyanesh; Choi, Taeyoyung

    2013-01-01

    In recent years, there has been a significant increase in the use of remotely sensed data to address global issues. With the open data policy, the data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Enhanced Thematic Mapper Plus (ETM+) sensors have become a critical component of numerous applications. These two sensors have been operational for more than a decade, providing a rich archive of multispectral imagery for analysis of mutitemporal remote sensing data. This paper focuses on evaluating the radiometric calibration agreement between MODIS and ETM+ using the near-simultaneous and cloud-free image pairs over an African pseudo-invariant calibration site, Libya 4. To account for the combined uncertainties in the top-of-atmosphere (TOA) reflectance due to surface and atmospheric bidirectional reflectance distribution function (BRDF), a semiempirical BRDF model was adopted to normalize the TOA reflectance to the same illumination and viewing geometry. In addition, the spectra from the Earth Observing-1 (EO-1) Hyperion were used to compute spectral corrections between the corresponding MODIS and ETM+ spectral bands. As EO-1 Hyperion scenes were not available for all MODIS and ETM+ data pairs, MODerate resolution atmospheric TRANsmission (MODTRAN) 5.0 simulations were also used to adjust for differences due to the presence or lack of absorption features in some of the bands. A MODIS split-window algorithm provides the atmospheric water vapor column abundance during the overpasses for the MODTRAN simulations. Additionally, the column atmospheric water vapor content during the overpass was retrieved using the MODIS precipitable water vapor product. After performing these adjustments, the radiometric cross-calibration of the two sensors was consistent to within 7%. Some drifts in the response of the bands are evident, with MODIS band 3 being the largest of about 6% over 10 years, a change that will be corrected in Collection 6 MODIS processing.

  10. Anisotropic reflectance characteristics of natural Earth surfaces.

    Science.gov (United States)

    Brennan, B; Bandeen, W R

    1970-02-01

    The patterns of reflection of solar radiation from cloud, water, and land surfaces were measured with an aircraft-borne medium resolution radiometer. Reflectances in the 0.2-4.0-micro and 0.55-0.85-micro portions of the electromagnetic spectrum were investigated. Results indicate that the reflectance characteristics of most of the surface types measured are anisotropic. The anisotropy is dependent on the type of surface and the angles of incidence and reflection. In general, the anisotropy increases with increasing solar zenith angle. Clouds and forests show similar reflectance patterns, with forward and backward scattering peaks. Ocean surfaces yield a pattern similar to those of the clouds and forests but with an additional peak which is associated with sun glitter. Reflectances measured in the 0.2-4.0-micro band are generally lower than those in the 0.55-0.85-micro band under cloudy conditions. Anisotropy and spectral bandwidth should be accounted for when computing the albedo of the earth from narrow field-of-view measurements from satellites; otherwise, large errors may be expected to occur.

  11. Lunar surface reflectance by LALT aboard KAGUYA

    Science.gov (United States)

    Noda, H.; Araki, H.; Ishihara, Y.; Tazawa, S.; Sasaki, S.; Kawano, N.

    2009-12-01

    The Laser Altimeter (LALT) aboard Japanese lunar explorer KAGUYA (SELENE) is a ranging instrument which measures the distance between the satellite and the lunar surface with accuracy of 1 m by detecting the timing delay of the reflected laser light. The main science goal of the LALT is to obtain the lunar global topographic data including polar regions for the study of the origin and the evolution of the Moon [1]. Besides, the LALT is equipped with an intensity monitor of the returned pulses. The intensity of the returned pulses contains information concerning surface roughness and reflectance of the footprints, which will contribute to the study of the lunar surface maturity and age. The reflectance at LALT wavelength (1064nm) is sensitive to the surface maturity and composition. The data should be particularly important at lunar polar regions where camera instruments should suffer from phase angle effects in the surface reflectance and moreover cannot obtain reflectance data at the permanently shadowed area. The normal operation of the LALT began on 30th, December 2007 after two months’ commissioning phase. Before the end of the normal operation phase in October 2008, the LALT measured more than 10 million range data. Unfortunately, due to the laser power decrease and also possible smaller surface reflectance than the expected value before launch (15 % at 1 micro meter), the return pulse intensity during the nominal mission phase is so small that they are not reliable enough to discuss the surface property. During the extended mission phase, which started November 2008, the satellite altitude decreased to 50 km. Due to the malfunction of the reaction wheel and high-voltage instruments were shutdown, the observation was suspended until 11th of February, 2009. LALT successfully resumed observation on 12th February and continued observation until the controlled crash of KAGUYA onto the Moon on 10th of June, 2009. Thanks to the lower orbit during this phase, the

  12. Surface composition of Mercury from reflectance spectrophotometry

    Science.gov (United States)

    Vilas, Faith

    1988-01-01

    The controversies surrounding the existing spectra of Mercury are discussed together with the various implications for interpretations of Mercury's surface composition. Special attention is given to the basic procedure used for reducing reflectance spectrophotometry data, the factors that must be accounted for in the reduction of these data, and the methodology for defining the portion of the surface contributing the greatest amount of light to an individual spectrum. The application of these methodologies to Mercury's spectra is presented.

  13. Reflectance spectroscopy and asteroid surface mineralogy

    International Nuclear Information System (INIS)

    Gaffey, M.J.; Bell, J.F.; Cruikshank, D.P.

    1989-01-01

    Information available from reflectance spectroscopy on the surface mineralogy of asteroids is discussed. Current spectral interpretive procedures used in the investigations of asteroid mineralogy are described. Present understanding of the nature and history of asteroids is discussed together with some still unresolved issues such as the source of ordinary chondrites. 100 refs

  14. Use of reflective surfaces on roadway embankment

    DEFF Research Database (Denmark)

    Jørgensen, Anders Stuhr; Doré, Guy

    2007-01-01

    Temperature measurements have been used to study the effect of two reflective surfaces on a roadway embankment in Forêt Montmorency, Québec, Canada. Both tested materials, Mapelastic (from MAPEI) and Colored Slurry (from Tech-Mix), have lead to a reduction in n-factor and proved to have very good...

  15. Conversion from surface wave to surface wave on reflection

    DEFF Research Database (Denmark)

    Novitsky, Andrey

    2010-01-01

    can be transmitted without changing its direction (nevertheless the amplitude varies). For other media parameters, only normally incident surface waves can be converted to surface waves. We propose applications of the predicted conversion as a beam splitter and polarization filter for surface waves.......We discuss the reflection and transmission of an incident surface wave to a pure surface wave state at another interface. This is allowed only for special media parameters: at least one of the media must be magnetic. We found such material characteristics that the obliquely incident surface wave...

  16. Light calibration and quality assessment methods for Reflectance Transformation Imaging applied to artworks' analysis

    Science.gov (United States)

    Giachetti, A.; Daffara, C.; Reghelin, C.; Gobbetti, E.; Pintus, R.

    2015-06-01

    In this paper we analyze some problems related to the acquisition of multiple illumination images for Polynomial Texture Maps (PTM) or generic Reflectance Transform Imaging (RTI). We show that intensity and directionality nonuniformity can be a relevant issue when acquiring manual sets of images with the standard highlight-based setup both using a flash lamp and a LED light. To maintain a cheap and flexible acquisition setup that can be used on field and by non-experienced users we propose to use a dynamic calibration and correction of the lights based on multiple intensity and direction estimation around the imaged object during the acquisition. Preliminary tests on the results obtained have been performed by acquiring a specifically designed 3D printed pattern in order to see the accuracy of the acquisition obtained both for spatial discrimination of small structures and normal estimation, and on samples of different types of paper in order to evaluate material discrimination. We plan to design and build from our analysis and from the tools developed and under development a set of novel procedures and guidelines that can be used to turn the cheap and common RTI acquisition setup from a simple way to enrich object visualization into a powerful method for extracting quantitative characterization both of surface geometry and of reflective properties of different materials. These results could have relevant applications in the Cultural Heritage domain, in order to recognize different materials used in paintings or investigate the ageing status of artifacts' surface.

  17. Simultaneous calibration of surface flow and baseflow simulations: A revisit of the SWAT model calibration framework

    Science.gov (United States)

    Accurate analysis of water flow pathways from rainfall to streams is critical for simulating water use, climate change impact, and contaminant transport. In this study, we developed a new scheme to simultaneously calibrate surface flow (SF) and baseflow (BF) simulations of Soil and Water Assessment ...

  18. VIIRS reflective solar bands on-orbit calibration and performance: a three-year update

    Science.gov (United States)

    Sun, Junqiang; Wang, Menghua

    2014-11-01

    The on-orbit calibration of the reflective solar bands (RSBs) of VIIRS and the result from the analysis of the up-to-date 3 years of mission data are presented. The VIIRS solar diffuser (SD) and lunar calibration methodology are discussed, and the calibration coefficients, called F-factors, for the RSBs are given for the latest reincarnation. The coefficients derived from the two calibrations are compared and the uncertainties of the calibrations are discussed. Numerous improvements are made, with the major improvement to the calibration result come mainly from the improved bidirectional reflectance factor (BRF) of the SD and the vignetting functions of both the SD screen and the sun-view screen. The very clean results, devoid of many previously known noises and artifacts, assures that VIIRS has performed well for the three years on orbit since launch, and in particular that the solar diffuser stability monitor (SDSM) is functioning essentially without flaws. The SD degradation, or H-factors, for most part shows the expected decline except for the surprising rise on day 830 lasting for 75 days signaling a new degradation phenomenon. Nevertheless the SDSM and the calibration methodology have successfully captured the SD degradation for RSB calibration. The overall improvement has the most significant and direct impact on the ocean color products which demands high accuracy from RSB observations.

  19. Alignment and calibration of total internal reflection fluorescence microscopy systems.

    Science.gov (United States)

    Toomre, Derek

    2012-04-01

    Live cell fluorescent microscopy is important in elucidating dynamic cellular processes such as cell signaling, membrane trafficking, and cytoskeleton remodeling. Often, transient intermediate states are revealed only when imaged and quantitated at the single-molecule, vesicle, or organelle level. Such insight depends on the spatiotemporal resolution and sensitivity of a given microscopy method. Confocal microscopes optically section the cell and improve image contrast and axial resolution (>600 nm) compared with conventional epifluorescence microscopes. Another approach, which can selectively excite fluorophores in an even thinner optical plane (microscopy (TIRFM). The key principle of TIRFM is that a thin, exponentially decaying, evanescent field of excitation can be generated at the interface of two mediums of different refractive index (RI) (e.g., the glass coverslip and the biological specimen); as such, TIRFM is ill-suited to deep imaging of cells or tissue. However, for processes near the lower cell cortex, the sensitivity of TIRFM is exquisite. The recent availability of a very high numerical-aperture (NA) objective lens (>1.45) and turnkey TIRFM systems by all the major microscopy manufacturers has made TIRFM increasingly accessible and attractive to biologists, especially when performed in a quantitative manner and complemented with orthogonal genetic and molecular manipulations. This protocol describes the procedure for alignment and calibration of TIRFM systems using standard cellular samples. The goal is to correctly collimate and align the TIRF illuminator vis-à-vis the downstream optics. For illustration, a 488-nm laser and green fluorescent protein (GFP) filter cube are used.

  20. Radiation pressure calibration and test mass reflectivities for LISA Pathfinder

    Science.gov (United States)

    Korsakova, Natalia; Kaune, Brigitte; LPF Collaboration

    2017-05-01

    This paper describes a series of experiments which were carried out during the main operations of LISA Pathfinder. These experiments were performed by modulating the power of the measurement and reference beams. In one series of experiments the beams were sequentially switched on and off. In the other series of experiments the powers of the beams were modulated within 0.1% and 1% of the constant power. These experiments use recordings of the total power measured on the photodiodes to infer the properties of the Optical Metrology System (OMS), such as reflectivities of the test masses and change of the photodiode efficiencies with time. In the first case the powers are back propagated from the different photodiodes to the same place on the optical bench to express the unknown quantities in the measurement with the complimentary photodiode measurements. They are combined in the way that the only unknown left is the test mass reflectivities. The second experiment compared two estimates of the force applied to the test masses due to the radiation pressure that appears because of the beam modulations. One estimate of the force is inferred from the measurements of the powers on the photodiodes and propagation of this measurement to the test masses. The other estimation of the force is done by calculating it from the change in the main scientific output of the instrument - differential displacement of the two test masses.

  1. Simulation Tool for GNSS Ocean Surface Reflections

    DEFF Research Database (Denmark)

    Høeg, Per; von Benzon, Hans-Henrik; Durgonics, Tibor

    2015-01-01

    . This impedance concept gives an accurate lower boundary condition in the determination of the electromagnetic field, and makes itpossible to simulate reflections and the effects of transitions between different mediums. A semi-isotropic Philipsspectrum is used to represent the air-sea interaction.Simulated GPS...... on the solution of the parabolic equation. The parabolic equation in our simulator is solvedusing the split-step sine transformation. The Earth’s surface is modeled with the use of an impedance model. The value of the Earth impedance is given as a function of the range along the surface of the Earth...

  2. ASTER L2 Surface Reflectance SWIR and ASTER L2 Surface Reflectance VNIR V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The ASTER L2 Surface Reflectance is a multi-file product that contains atmospherically corrected data for both the Visible Near-Infrared (VNIR) and Shortwave...

  3. Self-Calibration Method Based on Surface Micromaching of Light Transceiver Focal Plane for Optical Camera

    Directory of Open Access Journals (Sweden)

    Jin Li

    2016-10-01

    Full Text Available In remote sensing photogrammetric applications, inner orientation parameter (IOP calibration of remote sensing camera is a prerequisite for determining image position. However, achieving such a calibration without temporal and spatial limitations remains a crucial but unresolved issue to date. The accuracy of IOP calibration methods of a remote sensing camera determines the performance of image positioning. In this paper, we propose a high-accuracy self-calibration method without temporal and spatial limitations for remote sensing cameras. Our method is based on an auto-collimating dichroic filter combined with a surface micromachining (SM point-source focal plane. The proposed method can autonomously complete IOP calibration without the need of outside reference targets. The SM procedure is used to manufacture a light transceiver focal plane, which integrates with point sources, a splitter, and a complementary metal oxide semiconductor sensor. A dichroic filter is used to fabricate an auto-collimation light reflection element. The dichroic filter, splitter, and SM point-source focal plane are integrated into a camera to perform an integrated self-calibration. Experimental measurements confirm the effectiveness and convenience of the proposed method. Moreover, the method can achieve micrometer-level precision and can satisfactorily complete real-time calibration without temporal or spatial limitations.

  4. Gafchromic EBT2 film dosimetry in reflection mode with a novel plan-based calibration method.

    Science.gov (United States)

    Mendez, I; Hartman, V; Hudej, R; Strojnik, A; Casar, B

    2013-01-01

    A dosimetric system formed by Gafchromic EBT2 radiochromic film and Epson Expression 10000XL flatbed scanner was commissioned for dosimetry. In this paper, several open questions concerning the commissioning of radiochromic films for dosimetry were addressed: (a) is it possible to employ this dosimetric system in reflection mode; (b) if so, can the methods used in transmission mode also be used in reflection mode; (c) is it possible to obtain accurate absolute dose measurements with Gafchromic EBT2 films; (d) which calibration method should be followed; (e) which calibration models should be used; and (f) does three-color channel dosimetry offer a significant improvement over single channel dosimetry. The purpose of this paper is to help clarify these questions. In this study, films were scanned in reflection mode, the effect of surrounding film was evaluated and the feasibility of EBT2 film dosimetry in reflection mode was studied. EBT2's response homogeneity has been reported to lead to excessive dose uncertainties. To overcome this problem, a new plan-based calibration method was implemented. Plan-based calibration can use every pixel and each of the three color channels of the scanned film to obtain the parameters of the calibration model. A model selection analysis was conducted to select lateral correction and sensitometric curve models. The commonly used calibration with fragments was compared with red-channel plan-based calibration and with three-channel plan-based calibration. No effect of surrounding film was found in this study. The film response inhomogeneity in EBT2 films was found to be important not only due to differences in the fog but also due to differences in sensitivity. The best results for lateral corrections were obtained using absolute corrections independent of the dose. With respect to the sensitometric curves, an empirical polynomial fit of order 4 was found to obtain results equivalent to a gamma-distributed single hit model based on

  5. Reduction of Glass Surface Reflectance by Ion Beam Surface Modification

    Energy Technology Data Exchange (ETDEWEB)

    Mark Spitzer

    2011-03-11

    This is the final report for DOE contract DE-EE0000590. The purpose of this work was to determine the feasibility of the reduction of the reflection from the front of solar photovoltaic modules. Reflection accounts for a power loss of approximately 4%. A solar module having an area of one square meter with an energy conversion efficiency of 18% generates approximately 180 watts. If reflection loss can be eliminated, the power output can be increased to 187 watts. Since conventional thin-film anti-reflection coatings do not have sufficient environmental stability, we investigated the feasibility of ion beam modification of the glass surface to obtain reduction of reflectance. Our findings are generally applicable to all solar modules that use glass encapsulation, as well as commercial float glass used in windows and other applications. Ion implantation of argon, fluorine, and xenon into commercial low-iron soda lime float glass, standard float glass, and borosilicate glass was studied by implantation, annealing, and measurement of reflectance. The three ions all affected reflectance. The most significant change was obtained by argon implantation into both low-iron and standard soda-lime glass. In this way samples were formed with reflectance lower than can be obtained with a single-layer coatings of magnesium fluoride. Integrated reflectance was reduced from 4% to 1% in low-iron soda lime glass typical of the glass used in solar modules. The reduction of reflectance of borosilicate glass was not as large; however borosilicate glass is not typically used in flat plate solar modules. Unlike conventional semiconductor ion implantation doping, glass reflectance reduction was found to be tolerant to large variations in implant dose, meaning that the process does not require high dopant uniformity. Additionally, glass implantation does not require mass analysis. Simple, high current ion implantation equipment can be developed for this process; however, before the process

  6. The reflective surface of the MAGIC telescope

    Science.gov (United States)

    Doro, M.; Bastieri, D.; Biland, A.; Dazzi, F.; Font, L.; Garczarczyk, M.; Ghigo, M.; Giro, E.; Goebel, F.; Kosyra, R.; Lorenz, E.; Mariotti, M.; Mirzoyan, R.; Peruzzo, L.; Pareschi, G.; Zapatero, J.

    2008-09-01

    The atmospheric Cherenkov telescope MAGIC for ground-based gamma-ray astronomy is operating since late 2003 on the Canary island of La Palma. Its 17 m diameter mirror is composed of 964 square all-aluminum mirrors of ˜0.5m side, making up a parabola of 236 m2 area. Each mirror is composed of a sandwich of two thin aluminum layers interspaced by a honeycomb structure that ensures rigidity, high temperature conductivity and low weight. The surface of each raw blank is diamond milled to provide high reflectivity and a slightly different focal length to fit the overall parabolic shape of the reflector. We report about the stability and performance of the surface exposed to the atmosphere for over 3 years. For the construction of the clone of the first telescope, dubbed MAGIC II, major improvements of the design and performance of the reflective surface were required. Given the good experience with aluminum mirrors, a similar assembly was tested, but the area was increased to 1 m2, which allowed to skip the inter-alignment of four mirrors within a panel and to reduce substantially the weight. The increased rigidity of the mirror unit resulted in an improved focussing quality. In addition, a second class of mirrors will be installed in the outermost part of the reflector, namely glass mirrors obtained by cold-slumping replica technique. Details on the construction of both type MAGIC II new mirrors and the 17 m reflector will be presented.

  7. Calibration and verification of surface contamination meters --- Procedures and techniques

    International Nuclear Information System (INIS)

    Schuler, C; Butterweck, G.; Wernli, C.; Bochud, F.; Valley, J.-F.

    2007-03-01

    A standardised measurement procedure for surface contamination meters (SCM) is presented. The procedure aims at rendering surface contamination measurements to be simply and safely interpretable. Essential for the approach is the introduction and common use of the radionuclide specific quantity 'guideline value' specified in the Swiss Radiation Protection Ordinance as unit for the measurement of surface activity. The according radionuclide specific 'guideline value count rate' can be summarized as verification reference value for a group of radionuclides ('basis guideline value count rate'). The concept can be generalized for SCM of the same type or for SCM of different types using he same principle of detection. A SCM multi source calibration technique is applied for the determination of the instrument efficiency. Four different electron radiation energy regions, four different photon radiation energy regions and an alpha radiation energy region are represented by a set of calibration sources built according to ISO standard 8769-2. A guideline value count rate representing the activity per unit area of a surface contamination of one guideline value can be calculated for any radionuclide using instrument efficiency, radionuclide decay data, contamination source efficiency, guideline value averaging area (100 cm 2 ), and radionuclide specific guideline value. n this way, instrument responses for the evaluation of surface contaminations are obtained for radionuclides without available calibration sources as well as for short-Iived radionuclides, for which the continuous replacement of certified calibration sources can lead to unreasonable costs. SCM verification is based on surface emission rates of reference sources with an active area of 100 cm 2 . The verification for a given list of radionuclides is based on the radionuclide specific quantity guideline value count rate. Guideline value count rates for groups of radionuclides can be represented within the maximum

  8. Advances in calibration methods for micro- and nanoscale surfaces

    Science.gov (United States)

    Leach, R. K.; Giusca, C. L.; Coupland, J. M.

    2012-04-01

    Optical surface topography measuring instrument manufacturers often quote accuracies of the order of nanometres and claim that the instruments can reliably measure a range of surfaces with structures on the micro- to nanoscale. However, for many years there has been debate about the interpretation of the data from optical surface topography measuring instruments. Optical artefacts in the output data and a lack of a calibration infrastructure mean that it can be difficult to get optical instruments to agree with contact stylus instruments. In this paper, the current situation with areal surface topography measurements is discussed along with the ISO specification standards that are in draft form. An infrastructure is discussed whereby the ISO-defined metrological characteristics of optical instruments can be determined, but these characteristics do not allow the instrument to measure complex surfaces. Current research into methods for determining the transfer function of optical instruments is reviewed, which will allow the calibration of optical instruments to measure complex surfaces, at least in the case of weak scattering. The ability of some optical instruments to measure outside the spatial bandwidth limitation of the numerical aperture is presented and some general outlook for future work given.

  9. Formation of Reflecting Surfaces Based on Spline Methods

    Science.gov (United States)

    Zamyatin, A. V.; Zamyatina, E. A.

    2017-11-01

    The article deals with problem of reflecting barriers surfaces generation by spline methods. The cases of reflection when a geometric model is applied are considered. The surfaces of reflecting barriers are formed in such a way that they contain given points and the rays reflected at these points and hit at the defined points of specified surface. The reflecting barrier surface is formed by cubic splines. It enables a comparatively simple implementation of proposed algorithms in the form of software applications. The algorithms developed in the article can be applied in architecture and construction design for reflecting surface generation in optics and acoustics providing the geometrical model of reflex processes is used correctly.

  10. Calibration

    International Nuclear Information System (INIS)

    Greacen, E.L.; Correll, R.L.; Cunningham, R.B.; Johns, G.G.; Nicolls, K.D.

    1981-01-01

    Procedures common to different methods of calibration of neutron moisture meters are outlined and laboratory and field calibration methods compared. Gross errors which arise from faulty calibration techniques are described. The count rate can be affected by the dry bulk density of the soil, the volumetric content of constitutional hydrogen and other chemical components of the soil and soil solution. Calibration is further complicated by the fact that the neutron meter responds more strongly to the soil properties close to the detector and source. The differences in slope of calibration curves for different soils can be as much as 40%

  11. Monitoring the On-Orbit Calibration of Terra MODIS Reflective Solar Bands Using Simultaneous Terra MISR Observations

    Science.gov (United States)

    Angal, Amit; Xiong, Xiaoxiong; Wu, Aisheng

    2016-01-01

    On December 18, 2015, the Terra spacecraft completed 16 years of successful operation in space. Terra has five instruments designed to facilitate scientific measurements of the earths land, ocean, and atmosphere. The Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multiangle Imaging Spectroradiometer (MISR) instruments provide information for the temporal studies of the globe. After providing over 16 years of complementary measurements, a synergistic use of the measurements obtained from these sensors is beneficial for various science products. The 20 reflective solar bands (RSBs) of MODIS are calibrated using a combination of solar diffuser and lunar measurements, supplemented by measurements from pseudoinvariant desert sites. MODIS views the on-board calibrators and the earth via a two-sided scan mirror at three spatial resolutions: 250 m using 40 detectors in bands 1 and 2, 500 m using 20 detectors in bands 3 and 4, and 1000 m using 10 detectors in bands 819 and 26. Simultaneous measurements of the earths surface are acquired in a push-broom fashion by MISR at nine view angles spreading out in the forward and backward directions along the flight path. While the swath width for MISR acquisitions is 360 km, MODIS scans a wider swath of 2330 km via its two-sided scan mirror. The reflectance of the MODIS scan mirror has an angle dependence characterized by the response versus scan angle (RVS). Its on-orbit change is derived using the gain from a combination of on-board and earth-view measurements. The on-orbit RVS for MODIS has experienced a significant change, especially for the short-wavelength bands. The on-orbit RVS change for the short-wavelength bands (bands 3, 8, and 9) at nadir is observed to be greater than 10 over the mission lifetime. Due to absence of a scanning mechanism, MISR can serve as an effective tool to evaluate and monitor the on-orbit performance of the MODIS RVS. Furthermore, it can also monitor the detector and scan

  12. Aqua and Terra MODIS RSB Calibration Comparison Using BRDF Modeled Reflectance

    Science.gov (United States)

    Chang, Tiejun; Xiong, Xiaoxiong; Angal, Amit; Wu, Aisheng; Geng, Xu

    2017-01-01

    The inter-comparison of MODIS reflective solar bands onboard Aqua and Terra is very important for assessment of each instrument's calibration. One of the limitations is the lack of simultaneous nadir overpasses. Their measurements over a selected Earth view target have significant differences in solar and view angles, which magnify the effects of atmospheric scattering and Bidirectional Reflectance Distribution Function (BRDF). In this work, an intercomparison technique is formulated after correction for site's BRDF and atmospheric effects. The reflectance measurements over Libya desert sites 1, 2, and 4 from both the Aqua and Terra MODIS are regressed to a BRDF model with an adjustable coefficient accounting for calibration difference. The ratio between Aqua and Terra reflectance measurements are derived for bands 1 to 9 and the results from different sites show good agreement. For year 2003, the ratios are in the range of 0.985 to1.010 for band 1 to 9. Band 3 shows the lowest ratio 0.985 and band 1 shows the highest ratio 1.010. For the year 2014, the ratio ranges from approximately 0.983 for bands 2 and 1.012 for band 8. The BRDF corrected reflectance for the two instruments are also derived for every year from 2003 to 2014 for stability assessment. Bands 1 and 2 show greater than 1 differences between the two instruments. Aqua bands 1 and 2 show downward trends while Terra bands 1 and 2 show upward trends. Bands 8 and 9 of both Aqua and Terra show large variations of reflectance measurement over time.

  13. Calibration of Surface Plasmon Resonance Imager for Biochemical Detection

    Directory of Open Access Journals (Sweden)

    T. Ktari

    2012-01-01

    Full Text Available We present a new Surface Plasmon Resonance imager (SPRi based on immobilized T4-phage for bacteria detection. First, we present the sensitivity of the SPR imager towards refractive index variation for biosensor application. The SPR imager can be calibrated versus different percentage of triethylene glycol mixture in ultrapure water. The system can be used as a refractometer with sensitivity below 5×10−5 in the range of 1.33300–1.34360. Second, bacteriophage (T4-phage can be physisorbed on gold microarray spots for bacteria detection. The kinetic physisorption of different concentrations of T4-phages can be observed in real time. Finally, two types of bacteria such as E. coli (gram negative and Lactobacillus (gram positive were used for positive and negative tests. The results show a selectivity of T4-phage toward E. coli with a detection limit below 104 CFU/mL and with good reproducibility.

  14. Infrared spectral reflectances of asteroid surfaces

    Science.gov (United States)

    Larson, H. P.; Veeder, G. J.

    1979-01-01

    This review compares the types of compositional information produced by three complementary techniques used in infrared observations of asteroid surfaces: broadband JHKL photometry, narrow band photometry, and multiplex spectroscopy. The high information content of these infrared observations permits definitive interpretations of asteroid surface compositions in terms of the major meteoritic minerals (olivine, pyroxene, plagioclase feldspar, hydrous silicates, and metallic Ni-Fe). These studies emphasize the individuality of asteroid surface compositions, the inadequacy of simple comparisons with spectra of meteorites, and the need to coordinate spectral measurements of all types to optimize diagnostic capabilities.

  15. Calibration Standards for Surface Topography Measuring Systems down to Nanometric Range

    DEFF Research Database (Denmark)

    Trumpold, H.; De Chiffre, Leonardo; Andreasen, Jan Lasson

    Background For the precise and accurate measurement of surface topography a whole range of surface detection systems is available. With their application in research and production problems arise due to the lack of traceable standard artefacts for the instrument calibration in X, Y and Z directions...... to be replicated during all stages of the replication processes. Procedures for cleaning glass, PVC, PC, PMM and Ni-surfaces have been developed and tested. Calibration procedures for calibration standards and for calibrating instruments in X-, Y- and Z-direction have been developed and tested. Proposals...... in industries ranging from automotive manufacture to ultraprecision manufacture of data storage systems and compact discs. Objectives The project is concerned with developing calibration standards including their production methods and calibration procedures as a consistent means of calibrating different types...

  16. Characterization and flip angle calibration of 13C surface coils for hyperpolarization studies

    DEFF Research Database (Denmark)

    Hansen, Rie Beck; Gutte, Henrik; Larsen, Majbrit M E

    The aim of the present work is to address the challenge of optimal The aim of the present work is to address the challenge of optimal flflip angle calibration of ip angle calibration of C surface coils in C surface coils in hyperpolarization studies. To this end, we characterize the spatial pro h...

  17. Calibration of a distributed hydrology and land surface model using energy flux measurements

    DEFF Research Database (Denmark)

    Larsen, Morten Andreas Dahl; Refsgaard, Jens Christian; Jensen, Karsten H.

    2016-01-01

    In this study we develop and test a calibration approach on a spatially distributed groundwater-surface water catchment model (MIKE SHE) coupled to a land surface model component with particular focus on the water and energy fluxes. The model is calibrated against time series of eddy flux measure...

  18. Method and apparatus for aligning laser reflective surfaces

    International Nuclear Information System (INIS)

    Caruolo, A.B.; Davis, J.W.; Walch, A.P.

    1975-01-01

    Methods and apparatus used in the alignment of high power laser systems to obtain optimum performance are disclosed. An external source of visible radiation provides an alignment beam which is reflected along the axis of a resonator. Reflecting surfaces of the resonator are aligned with respect to the axis located by the visible beam

  19. Estimating surface reflectance from Himawari-8/AHI reflectance channels Using 6SV

    Science.gov (United States)

    Lee, Kyeong-sang; Choi, Sungwon; Seo, Minji; Seong, Noh-hun; Han, Kyung-soo

    2017-04-01

    TOA (Top Of Atmospheric) reflectance observed by satellite is modified by the influence of atmosphere such as absorbing and scattering by molecular and gasses. Removing TOA reflectance attenuation which is caused by the atmospheric is essential. surface reflectance with compensated atmospheric effects used as important input data for land product such as Normalized Difference Vegetation Index (NDVI), Land Surface Albedo (LSA) and etc. In this study, we Second Simulation of a Satellite Signal in the Solar Spectrum Vector (6SV) Radiative Transfer Model (RTM) for atmospheric correction and estimating surface reflectance from Himawari-8/Advanced Himawari Imager (AHI) reflectance channels. 6SV has the advantage that it has high accuracy by performing the atmospheric correction by dividing the width of the satellite channel by 2.5 nm, but it is slow to use in the operation. So, we use LUT approach to reduce the computation time and avoid the intensive calculation required for retrieving surface reflectance. Estimated surface reflectance data were compared with PROBA-V S1 data to evaluate the accuracy. As a result Root Mean Square Error (RMSE) and bias were about 0.05 and -0.02. It is considered that this error is due to the difference of angle component and Spectral Response Function (SRF) of each channel.

  20. 100% reflectivity from a monolithic dielectric microstructured surface

    OpenAIRE

    Brückner, F.; Clausnitzer, T.; Burmeister, O.; Friedrich, D.; Kley, E.; Danzmann, K.; Tünnermann, A.; Schnabel, R.

    2008-01-01

    Here, we propose a new mirror architecture which is solely based upon a monolithic dielectric micro-structured surface. Hence, the mirror device, which consists of a possibly mono-crystalline bulk material, can in principle simultaneously provide perfect reflectivity and lowest mechanical loss. By specifically structuring the monolithic surface, resulting in T-shaped ridges of a subwavelength grating, a resonant behavior of light coupling can be realized, leading to theoretically 100% reflect...

  1. Transitioning MODIS to VIIRS observations for Land: Surface Reflectance results, Status and Long-term Prospective

    Science.gov (United States)

    Vermote, E.

    2015-12-01

    Surface reflectance is one of the key products from VIIRS and as with MODIS, is used in developing several higher-order land products. The VIIRS Surface Reflectance (SR) IP is based on the heritage MODIS Collection 5 product (Vermote et al. 2002). The quality and character of surface reflectance depends on the accuracy of the VIIRS Cloud Mask (VCM) and aerosol algorithms and of course on the adequate calibration of the sensor. Early evaluation of the VIIRS SR product in the context of the maturity of the operational processing system known as the Interface Data Processing System (IDPS), has been a major focus of work to-date, but is now evolving into the development of a VIIRS suite of Climate Data Records produced by the NASA Land Science Investigator Processing System (SIPS). We will present the calibration performance and the role of the surface reflectance in calibration monitoring, the performance of the cloud mask with a focus on vegetation monitoring (no snow conditions), the performance of the aerosol input used in the atmospheric correction with quantitative results of the performance of the SR product over AERONET sites. Based on those elements and further assessment, we will address the readiness of the SR product for the production of higher-order land products such as Vegetation Indices, Albedo and LAI/FPAR, the its application to agricultural monitoring and in particular the integration of VIIRS data into the global agricultural monitoring (GLAM) system developed at UMd. Finally from the lessons learned, we will articulate a set of critical recommendations to ensure consistency and continuity of the JPSS mission with the MODIS data record.

  2. Calibration and Industrial Application of Instrument for Surface Mapping based on AFM

    DEFF Research Database (Denmark)

    Hansen, Hans Nørgaard; Kofod, Niels; De Chiffre, Leonardo

    2002-01-01

    The paper describes the calibration and application of an integrated system for topographic characterisation of fine surfaces on large workpieces. The system, consisting of an atomic force microscope mounted on a coordinate measuring machine, was especially designed for surface mapping, i.......e., measurement and tiling of adjacent areas. A calibration procedure was proposed involving a glass artefact featuring chromium lines with different pitch distances, giving the possibility to identify the exact position of single surface areas. The calibrated system was used to surface map a hip joint prosthesis...

  3. Diffuse reflection of ultracold neutrons from low-roughness surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Atchison, F.; Daum, M.; Henneck, R.; Horisberger, M.; Kirch, K.; Lauss, B.; Mtchedlishvili, A.; Meier, M.; Petzoldt, G.; Schelldorfer, R.; Zsigmond, G. [Paul Scherrer Institut, PSI, Villigen (Switzerland); Heule, S.; Knecht, A. [Paul Scherrer Institut, PSI, Villigen (Switzerland); University Zuerich, Zuerich (Switzerland); Kasprzak, M. [Paul Scherrer Institut, PSI, Villigen (Switzerland); Stefan Meyer Institut, Vienna (Austria); Kuzniak, M. [Paul Scherrer Institut, PSI, Villigen (Switzerland); Jagiellonian University, Smoluchowski Institute of Physics, Cracow (Poland); Plonka-Spehr, C. [Institut Laue Langevin, ILL, Grenoble (France); Straumann, U. [University Zuerich, Zuerich (Switzerland)

    2010-04-15

    We report a measurement of the reflection of ultracold neutrons from flat, large-area plates of different Fermi potential materials with low surface roughness. The results were used to test two diffuse reflection models, the well-known Lambert model and the micro-roughness model which is based on wave scattering. The Lambert model fails to reproduce the diffuse reflection data. The surface roughness b and correlation length w, obtained by fitting the micro-roughness model to the data are in the range 1{<=}b{<=}3 nm and 10{<=}w{<=}120 nm, in qualitative agreement with independent measurements using atomic force microscopy. (orig.)

  4. Diffuse reflection of ultracold neutrons from low-roughness surfaces

    International Nuclear Information System (INIS)

    Atchison, F.; Daum, M.; Henneck, R.; Horisberger, M.; Kirch, K.; Lauss, B.; Mtchedlishvili, A.; Meier, M.; Petzoldt, G.; Schelldorfer, R.; Zsigmond, G.; Heule, S.; Knecht, A.; Kasprzak, M.; Kuzniak, M.; Plonka-Spehr, C.; Straumann, U.

    2010-01-01

    We report a measurement of the reflection of ultracold neutrons from flat, large-area plates of different Fermi potential materials with low surface roughness. The results were used to test two diffuse reflection models, the well-known Lambert model and the micro-roughness model which is based on wave scattering. The Lambert model fails to reproduce the diffuse reflection data. The surface roughness b and correlation length w, obtained by fitting the micro-roughness model to the data are in the range 1≤b≤3 nm and 10≤w≤120 nm, in qualitative agreement with independent measurements using atomic force microscopy. (orig.)

  5. On the reflection point where light reflects to a known destination on quadratic surfaces.

    Science.gov (United States)

    Gonçalves, Nuno

    2010-01-15

    We address the problem of determining the reflection point on a specular surface where a light ray that travels from a source to a target is reflected. The specular surfaces considered are those expressed by a quadratic equation. So far, there is no closed form explicit equation for the general solution of this determination of the reflection point, and the usual approach is to use the Snell law or the Fermat principle whose equations are derived in multidimensional nonlinear minimizations. We prove in this Letter that one can impose a set of three restrictions to the reflection point that can impose a set of three restrictions that culminates in a very elegant formalism of searching the reflection point in a unidimensional curve in space. This curve is the intersection of two quadratic equations. Some applications of this framework are also discussed.

  6. A light reflecting apparatus including a multi-aberration light reflecting surface

    Science.gov (United States)

    Sawicki, R.H.; Sweatt, W.

    1985-11-21

    A light reflecting apparatus including a multi-aberration bendable light reflecting surface is disclosed herein. This apparatus includes a structural assembly comprised of a rectangular plate which is resiliently bendable, to a limited extent, and which has a front side defining the multi-aberration light reflecting surface and an opposite back side, and a plurality of straight leg members rigidly connected with the back side of the plate and extending rearwardly therefrom. The apparatus also includes a number of different adjustment mechanisms, each of which is connected with specific ones of the leg members. These mechanisms are adjustably movable in different ways for applying corresponding forces to the leg members in order to bend the rectangular plate and light reflecting surface into different predetermined curvatures and which specifically include quadratic and cubic curvatures corresponding to different optical aberrations.

  7. Calibration of the surface array of the Pierre Auger Observatory

    International Nuclear Information System (INIS)

    Aglietta, M.; Alision, P.S.; Arneodo, F.; Barnhill, D.; Bauleo, P.; Beatty, J.J.; Bertou, X.; Bonifazi, C.; Busca, N.; Creusot, A.; Dornic, D.; Etchegoyen, A.; Filevitch, A.; Ghia, P.L.; Grunfeld, C.M.; Lhenry-Yvon, I.; Medina, M.C.; Moreno, E.; Navarra, G.; Nitz, D.; Ohnuki, T.

    2005-01-01

    The ground array of the Pierre Auger Observatory will consist of 1600 water Cherenkov detectors, deployed over 3000 km 2 . The remoteness and large number of detectors required a simple, automatic remote calibration procedure. The primary physics calibration is based on the average charge deposited by a vertical and central throughgoing muon, determined with good precision at the detector via a novel rate-based technique and later with higher precision via charge histograms. This value is named the vertical-equivalent muon (VEM). The VEM and the other parameters needed to maintain this calibration over the full energy range and to assess the quality of the detector are measured every minute. This allows an accurate determination of the energy deposited in each detector when an atmospheric cosmic ray shower occurs

  8. A fiber-coupled displacement measuring interferometer for determination of the posture of a reflective surface

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Shuai; Hu, Peng-Cheng, E-mail: hupc@hit.edu.cn; Ding, Xue-Mei, E-mail: X.M.Ding@outlook.com; Tan, Jiu-Bin [Harbin Institute of Technology, D-403 Science Park, 2 Yikuang Street, Harbin 150080 (China)

    2016-08-15

    A fiber-coupled displacement measuring interferometer capable of determining of the posture of a reflective surface of a measuring mirror is proposed. The newly constructed instrument combines fiber-coupled displacement and angular measurement technologies. The proposed interferometer has advantages of both the fiber-coupled and the spatially beam-separated interferometer. A portable dual-position sensitive detector (PSD)-based unit within this proposed interferometer measures the parallelism of the two source beams to guide the fiber-coupling adjustment. The portable dual PSD-based unit measures not only the pitch and yaw of the retro-reflector but also measures the posture of the reflective surface. The experimental results of displacement calibration show that the deviations between the proposed interferometer and a reference one, Agilent 5530, at two different common beam directions are both less than ±35 nm, thus verifying the effectiveness of the beam parallelism measurement. The experimental results of angular calibration show that deviations of pitch and yaw with the auto-collimator (as a reference) are less than ±2 arc sec, thus proving the proposed interferometer’s effectiveness for determination of the posture of a reflective surface.

  9. A fiber-coupled displacement measuring interferometer for determination of the posture of a reflective surface

    Science.gov (United States)

    Mao, Shuai; Hu, Peng-Cheng; Ding, Xue-Mei; Tan, Jiu-Bin

    2016-08-01

    A fiber-coupled displacement measuring interferometer capable of determining of the posture of a reflective surface of a measuring mirror is proposed. The newly constructed instrument combines fiber-coupled displacement and angular measurement technologies. The proposed interferometer has advantages of both the fiber-coupled and the spatially beam-separated interferometer. A portable dual-position sensitive detector (PSD)-based unit within this proposed interferometer measures the parallelism of the two source beams to guide the fiber-coupling adjustment. The portable dual PSD-based unit measures not only the pitch and yaw of the retro-reflector but also measures the posture of the reflective surface. The experimental results of displacement calibration show that the deviations between the proposed interferometer and a reference one, Agilent 5530, at two different common beam directions are both less than ±35 nm, thus verifying the effectiveness of the beam parallelism measurement. The experimental results of angular calibration show that deviations of pitch and yaw with the auto-collimator (as a reference) are less than ±2 arc sec, thus proving the proposed interferometer's effectiveness for determination of the posture of a reflective surface.

  10. Shape from specular reflection in calibrated environments and the integration of spatial normal fields

    KAUST Repository

    Balzer, Jonathan

    2011-09-01

    Reflections of a scene in a mirror surface contain information on its shape. This information is accessible by measurement through an optical metrology technique called deflectometry. The result is a field of normal vectors to the unknown surface having the remarkable property that it equally changes in all spatial directions, unlike normal maps occurring, e.g., in Shape from Shading. Its integration into a zero-order reconstruction of the surface thus deserves special attention. We develop a novel algorithm for this purpose which is relatively straightforward to implement yet outperforms existing ones in terms of efficiency and robustness. Experimental results on synthetic and real data complement the theoretical discussion. © 2011 IEEE.

  11. Improved Calibration of Reflectance Data from the LRO Lunar Orbiter Laser Altimeter (LOLA) and Implications for Space Weathering

    Science.gov (United States)

    Lemelin, M.; Lucey, P. G.; Neumann, G. A.; Mazarico, E. M.; Barker, M. K.; Kakazu, A.; Trang, D.; Smith, D. E.; Zuber, M. T.

    2016-01-01

    The Lunar Orbiter Laser Altimeter (LOLA) experiment on Lunar Reconnaissance Orbiter (LRO) is a laser altimeter that also measures the strength of the return pulse from the lunar surface. These data have been used to estimate the reflectance of the lunar surface, including regions lacking direct solar illumination. A new calibration of these data is presented that features lower uncertainties overall and more consistent results in the polar regions. We use these data, along with newly available maps of the distribution of lunar maria, also derived from LRO instrument data, to investigate a newly discovered dependence of the albedo of the lunar maria on latitude (Hemingway et al., [2015]). We confirm that there is an increase in albedo with latitude in the lunar maria, and confirm that this variation is not an artifact arising from the distribution of compositions within the lunar maria, using data from the Lunar Prospector Neutron Spectrometer. Radiative transfer modeling of the albedo dependence within the lunar maria is consistent with the very weak to absent dependence of albedo on latitude in the lunar highlands; the lower abundance of the iron source for space weathering products in the lunar highlands weakens the latitude dependence to the extent that it is only weakly detectable in current data. In addition, photometric mod- els and normalization may take into account the fact that the lunar albedo is latitude dependent, but this dependence can cause errors in normalized reflectance of at most 2% for the majority of near-nadir geometries. We also investigate whether the latitude dependent albedo may have obscured detection of small mare deposits at high latitudes. We find that small regions at high latitudes with low roughness similar to the lunar maria are not mare deposits that may have been misclassified owing to high albedos imposed by the latitude dependence. Finally, we suggest that the only modest correlations among space weathering indicators defined

  12. Reflection properties of hydrogen ions at helium irradiated tungsten surfaces

    International Nuclear Information System (INIS)

    Doi, K; Tawada, Y; Kato, S; Sasao, M; Kenmotsu, T; Wada, M; Lee, H T; Ueda, Y; Tanaka, N; Kisaki, M; Nishiura, M; Matsumoto, Y; Yamaoka, H

    2016-01-01

    Nanostructured W surfaces prepared by He bombardment exhibit characteristic angular distributions of hydrogen ion reflection upon injection of 1 keV H + beam. A magnetic momentum analyzer that can move in the vacuum chamber has measured the angular dependence of the intensity and the energy of reflected ions. Broader angular distributions were observed for He-irradiated tungsten samples compared with that of the intrinsic polycrystalline W. Both intensity and energy of reflected ions decreased in the following order: the polycrystalline W, the He-bubble containing W, and the fuzz W. Classical trajectory Monte Carlo simulations based on Atomic Collision in Amorphous Target code suggests that lower atom density near the surface can make the reflection coefficients lower due to increasing number of collisions. (paper)

  13. SU-E-J-221: Advantages of a New Surface Imaging Calibration Method for SRS Treatments

    International Nuclear Information System (INIS)

    Paxton, A; Manger, R; Pawlicki, T; Kim, G

    2014-01-01

    Purpose: The present calibration method used for the AlignRT surface imaging system relies on the placement of a calibration plate at the linac isocenter using isocenter surrogates (crosshairs, room lasers, etc.). This work investigated the potential advantages of a new calibration method that shifts the AlignRT isocenter to be coincident with the linac MV beam isocenter. Methods: To quantify the potential uncertainties associated with the present calibration method for SRS treatments, the calibration plate was intentionally shifted away from isocenter +/−3mm in the longitudinal and lateral directions and +/−1mm in the longitudinal, lateral, and vertical directions. A head phantom was placed in a mock SRS treatment position and monitored with the AlignRT system. The AlignRT-indicated offsets were recorded at 270, 315, 0, 45, and 90° couch angles for each intentional calibration misalignment. The new isocenter calibration was applied after each misalignment, and the measurements were repeated and compared to the previous results. Results: With intentional longitudinal and lateral shifts of +/−3mm and +/−1mm in the calibration plate, the average indicated offsets at couch rotations of +/−90° were 4.3mm and 1.6mm, respectively. This was in agreement with the theoretical offset of sqrt(2)*(intentional shift of the calibration plate). Since vertical shifts were along the rotation axis of the couch, these shifts had little effect on the offsets with changing couch angle. When the new calibration was applied, the indicated offsets were all within 0.5mm for all couch angles. These offsets were in agreement with the known magnitude of couch walkout. Conclusion: The potential pitfalls of the present calibration method have been established, and the advantages of the new calibration method have been demonstrated. This new calibration method effectively removes the potential miscalibration artifacts of the present calibration method, giving the AlignRT user more

  14. Phase analysis for three-dimensional surface reconstruction of apples using structured-illumination reflectance imaging

    Science.gov (United States)

    Lu, Yuzhen; Lu, Renfu

    2017-05-01

    Three-dimensional (3-D) shape information is valuable for fruit quality evaluation. This study was aimed at developing phase analysis techniques for reconstruction of the 3-D surface of fruit from the pattern images acquired by a structuredillumination reflectance imaging (SIRI) system. Phase-shifted sinusoidal patterns, distorted by the fruit geometry, were acquired and processed through phase demodulation, phase unwrapping and other post-processing procedures to obtain phase difference maps relative to the phase of a reference plane. The phase maps were then transformed into height profiles and 3-D shapes in a world coordinate system based on phase-to-height and in-plane calibrations. A reference plane-based approach, coupled with the curve fitting technique using polynomials of order 3 or higher, was utilized for phase-to-height calibrations, which achieved superior accuracies with the root-mean-squared errors (RMSEs) of 0.027- 0.033 mm for a height measurement range of 0-91 mm. The 3rd-order polynomial curve fitting technique was further tested on two reference blocks with known heights, resulting in relative errors of 3.75% and 4.16%. In-plane calibrations were performed by solving a linear system formed by a number of control points in a calibration object, which yielded a RMSE of 0.311 mm. Tests of the calibrated system for reconstructing the surface of apple samples showed that surface concavities (i.e., stem/calyx regions) could be easily discriminated from bruises from the phase difference maps, reconstructed height profiles and the 3-D shape of apples. This study has laid a foundation for using SIRI for 3-D shape measurement, and thus expanded the capability of the technique for quality evaluation of horticultural products. Further research is needed to utilize the phase analysis techniques for stem/calyx detection of apples, and optimize the phase demodulation and unwrapping algorithms for faster and more reliable detection.

  15. Reflection characteristics of a composite planar AMC surface

    Directory of Open Access Journals (Sweden)

    Ruey-Bing Hwang

    2012-03-01

    Full Text Available This study investigates the reflection characteristics of a composite Artificial Magnetic Conductor (AMC surface consisting of multiple orthogonal gradient AMC surfaces arranged in a two-dimensional periodic pattern. The gradient AMC surface in this study consists of square metal patches of variable size printed on a grounded dielectric substrate. Due to the orthogonal placement of the gradient AMC surface, the incident energy of a plane wave normally incident on the composite AMC surface will be reflected into four major lobes away from the impinging direction. To achieve a systematical design, a simple formula based on array antenna theory was developed to determine the reflection pattern of the gradient AMC surface illuminated by a normal incident plane wave. A time-domain full-wave simulation was also carried out to calculate the electromagnetic fields in the structure and the far-field patterns. The scattering patterns of the structure were measured in an electromagnetic anechoic chamber. Results confirm the design principle and procedures in this research. Since such a composite AMC surface can be easily fabricated using the standard printed circuit board technique without via-hole process, it may have potential applications in beam-steering and radar cross section reduction.

  16. Relationship between microstructure of the skin surface and surface reflection based on geometric optics.

    Science.gov (United States)

    Yoshida, Kenichiro; Miyaki, Masahiro; Ojima, Nobutoshi; Iwata, Kayoko

    2012-06-01

    The behavior of reflected light in skin affects skin appearance and provides clues as to the internal condition of the skin. Surface topography is one of the central physical factors contributing to surface reflection. We tried to clarify the relationship between microstructure of the skin surface and surface reflection based on geometric optics. Microstructures and surface reflections in the left cheeks of adult females were evaluated. Skin topography was acquired measuring replicas using confocal laser microscopy. Surface topography was used to calculate arithmetical mean deviation of the surface (S(a)), and geometric index from gradient of the surface (S(grad)), which is expected to correlate with the directionality of surface reflection (DoSR) based on geometric optics. A surface reflection image was acquired from differently polarized pictures of a face, and the index of surface reflection (I(obs)) was calculated as the average pixel value of the area of shine. Correlations between indices were then evaluated. S(grad) and S(a) showed significant correlation (preflection from the reflection model than S(a). In addition, S(grad) can explain differences in DoSR for some panelists even in the case of an identical S(a). The topographic element involved in DoSR was extracted from height mapping. S(grad) reflects the ratio of flat area, offering a more effective indicator than S(a) for distinguishing topographic characteristics with respect to surface reflection. Copyright © 2012 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

  17. Effective area calibration of the reflection grating spectrometers of XMM-Newton. II. X-ray spectroscopy of DA white dwarfs

    NARCIS (Netherlands)

    Kaastra, J.S.|info:eu-repo/dai/nl/070911134; Lanz, T.M.|info:eu-repo/dai/nl/304846147; Hubeny, I.; Paerels, F.

    2009-01-01

    Context. White dwarf spectra have been widely used as a calibration source for X-ray and EUV instruments. The in-flight effective area calibration of the reflection grating spectrometers (RGS) of XMM-Newton depend upon the availability of reliable calibration sources. Aims. We investigate how well

  18. Quality Assessment of Landsat Surface Reflectance Products Using MODIS Data

    Science.gov (United States)

    Feng, Min; Huang, Chengquan; Channan, Saurabh; Vermote, Eric; Masek, Jeffrey G.; Townshend, John R.

    2012-01-01

    Surface reflectance adjusted for atmospheric effects is a primary input for land cover change detection and for developing many higher level surface geophysical parameters. With the development of automated atmospheric correction algorithms, it is now feasible to produce large quantities of surface reflectance products using Landsat images. Validation of these products requires in situ measurements, which either do not exist or are difficult to obtain for most Landsat images. The surface reflectance products derived using data acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS), however, have been validated more comprehensively. Because the MODIS on the Terra platform and the Landsat 7 are only half an hour apart following the same orbit, and each of the 6 Landsat spectral bands overlaps with a MODIS band, good agreements between MODIS and Landsat surface reflectance values can be considered indicators of the reliability of the Landsat products, while disagreements may suggest potential quality problems that need to be further investigated. Here we develop a system called Landsat-MODIS Consistency Checking System (LMCCS). This system automatically matches Landsat data with MODIS observations acquired on the same date over the same locations and uses them to calculate a set of agreement metrics. To maximize its portability, Java and open-source libraries were used in developing this system, and object-oriented programming (OOP) principles were followed to make it more flexible for future expansion. As a highly automated system designed to run as a stand-alone package or as a component of other Landsat data processing systems, this system can be used to assess the quality of essentially every Landsat surface reflectance image where spatially and temporally matching MODIS data are available. The effectiveness of this system was demonstrated using it to assess preliminary surface reflectance products derived using the Global Land Survey (GLS) Landsat

  19. Error Budget for a Calibration Demonstration System for the Reflected Solar Instrument for the Climate Absolute Radiance and Refractivity Observatory

    Science.gov (United States)

    Thome, Kurtis; McCorkel, Joel; McAndrew, Brendan

    2013-01-01

    A goal of the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission is to observe highaccuracy, long-term climate change trends over decadal time scales. The key to such a goal is to improving the accuracy of SI traceable absolute calibration across infrared and reflected solar wavelengths allowing climate change to be separated from the limit of natural variability. The advances required to reach on-orbit absolute accuracy to allow climate change observations to survive data gaps exist at NIST in the laboratory, but still need demonstration that the advances can move successfully from to NASA and/or instrument vendor capabilities for spaceborne instruments. The current work describes the radiometric calibration error budget for the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. The goal of the CDS is to allow the testing and evaluation of calibration approaches, alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a test-bed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. The resulting SI-traceable error budget for reflectance retrieval using solar irradiance as a reference and methods for laboratory-based, absolute calibration suitable for climatequality data collections is given. Key components in the error budget are geometry differences between the solar and earth views, knowledge of attenuator behavior when viewing the sun, and sensor behavior such as detector linearity and noise behavior. Methods for demonstrating this error budget are also presented.

  20. An instrument for the measurement of road surface reflection properties

    DEFF Research Database (Denmark)

    Corell, Dennis Dan; Sørensen, K.

    2017-01-01

    Road surface reflection data in the form of standard r-tables serve as input for design calculations of road lighting installations on traffic roads. However, in several countries the use of the standard r-tables has not been verified by measurement in a long period of time, while the types of road...

  1. Quality-factor and reflection-coefficient estimation using reflected surface waves

    NARCIS (Netherlands)

    Draganov, D.S.; Ruigrok, E.N.; Ghose, R.; Mikesell, D.; Van Wijk, K.

    2014-01-01

    We propose a method for estimating the reflection coefficient of a subvertical boundary and the the quality factor of the medium between a receiver and the subvertical boundary. The method uses surface waves from transient deterministic sources and is inspired by the occurrence of non-physical

  2. Copper-assisted, anti-reflection etching of silicon surfaces

    Science.gov (United States)

    Toor, Fatima; Branz, Howard

    2014-08-26

    A method (300) for etching a silicon surface (116) to reduce reflectivity. The method (300) includes electroless deposition of copper nanoparticles about 20 nanometers in size on the silicon surface (116), with a particle-to-particle spacing of 3 to 8 nanometers. The method (300) includes positioning (310) the substrate (112) with a silicon surface (116) into a vessel (122). The vessel (122) is filled (340) with a volume of an etching solution (124) so as to cover the silicon surface (116). The etching solution (124) includes an oxidant-etchant solution (146), e.g., an aqueous solution of hydrofluoric acid and hydrogen peroxide. The silicon surface (116) is etched (350) by agitating the etching solution (124) with, for example, ultrasonic agitation, and the etching may include heating (360) the etching solution (124) and directing light (365) onto the silicon surface (116). During the etching, copper nanoparticles enhance or drive the etching process.

  3. Mercury's Surface Magnetic Field Determined from Proton-Reflection Magnetometry

    Science.gov (United States)

    Winslow, Reka M.; Johnson, Catherine L.; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Lillis, Robert J.; Korth, Haje; Slavin, James A.; Solomon, Sean C.; Zurbuchen, Thomas H.; hide

    2014-01-01

    Solar wind protons observed by the MESSENGER spacecraft in orbit about Mercury exhibit signatures of precipitation loss to Mercury's surface. We apply proton-reflection magnetometry to sense Mercury's surface magnetic field intensity in the planet's northern and southern hemispheres. The results are consistent with a dipole field offset to the north and show that the technique may be used to resolve regional-scale fields at the surface. The proton loss cones indicate persistent ion precipitation to the surface in the northern magnetospheric cusp region and in the southern hemisphere at low nightside latitudes. The latter observation implies that most of the surface in Mercury's southern hemisphere is continuously bombarded by plasma, in contrast with the premise that the global magnetic field largely protects the planetary surface from the solar wind.

  4. THE CHARGE STATE OF POLYCYCLIC AROMATIC HYDROCARBONS ACROSS REFLECTION NEBULAE: PAH CHARGE BALANCE AND CALIBRATION

    Energy Technology Data Exchange (ETDEWEB)

    Boersma, C.; Bregman, J.; Allamandola, L. J., E-mail: Christiaan.Boersma@nasa.gov [NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-0001 (United States)

    2016-11-20

    Low-resolution Spitzer spectral map data (>1700 spectra) of ten reflection nebulae (RNe) fields are analyzed using the data and tools available through the NASA Ames PAH IR Spectroscopic Database. The PAH emission is broken down into PAH charge state using a database fitting approach. Here, the physics of the PAH emission process is taken into account and uses target appropriate parameters, e.g., a stellar radiation model for the exciting star. The breakdown results are combined with results derived using the traditional PAH band strength approach, which interprets particular PAH band strength ratios as proxies for the PAH charge state, e.g., the 6.2/11.2 μ m PAH band strength ratio. These are successfully calibrated against their database equivalent; the PAH ionized fraction ( f {sub i} ). The PAH ionized fraction is converted into the PAH ionization parameter, which relates the PAH ionized fraction to the strength of the radiation field, gas temperature and electron density. The behavior of the 12.7 μ m PAH band is evaluated as a tracer for PAH ionization and erosion. The plot of the 8.6 versus 11.2 μ m PAH band strength for the northwest photo-dominated region (PDR) in NGC 7023 is shown to be a robust diagnostic template for the PAH ionized fraction. Remarkably, most of the other RNe fall within the limits set by NGC 7023. Finally, PAH spectroscopic templates are constructed and verified as principal components. Template spectra derived from NGC 7023 and NGC 2023 compare extremely well with each other, with those derived for NGC 7023 successfully reproducing the PAH emission observed from NGC 2023.

  5. Excitations of surface plasmon polaritons by attenuated total reflection, revisited

    International Nuclear Information System (INIS)

    Barchesi, D.; Otto, A.

    2013-01-01

    Many textbooks and review papers are devoted to plasmonics based on a selection of the numerous bibliography. But none describes the details of the first culmination of plasmonics in 1968, when surface plasmons become a field of optics. The coupling of light with the surface plasmon leads to the surface plasmon polariton (SPP). Therefore, the authors chose to associate historical insight (not avoiding a personal touch), a modern mathematical formulation of the excitation of the SPP by attenuated total reflection (ATR), considered as well understood since decades, and experimental applications since 1969, including recent developments.

  6. An instrument for the measurement of road surface reflection properties

    DEFF Research Database (Denmark)

    Corell, Dennis Dan; Sørensen, K.

    2017-01-01

    Road surface reflection data in the form of standard r-tables serve as input for design calculations of road lighting installations on traffic roads. However, in several countries the use of the standard r-tables has not been verified by measurement in a long period of time, while the types of road...... surfaces in use have changed - for instance to road surface types with less noise from wheel passages. Because of this, a co-operation between the road administrations of the Nordic countries (abbreviated NMF) decided to construct a portable instrument to be used on selections of traffic roads within...

  7. Reflectance variability of surface coatings reveals characteristic eigenvalue spectra

    Science.gov (United States)

    Medina, José M.; Díaz, José A.; Barros, Rui

    2012-10-01

    We have examined the trial-to-trial variability of the reflectance spectra of surface coatings containing effect pigments. Principal component analysis of reflectances was done at each detection angle separately. A method for classification of principal components is applied based on the eigenvalue spectra. It was found that the eigenvalue spectra follow characteristic power laws and depend on the detection angle. Three different subsets of principal components were examined to separate the relevant spectral features related to the pigments from other noise sources. Reconstruction of the reflectance spectra by taking only the first subset indicated that reflectance variability was higher at near-specular reflection, suggesting a correlation with the trial-to-trial deposition of effect pigments. Reconstruction by using the second subset indicates that variability was higher at short wavelengths. Finally, reconstruction by using only the third subset indicates that reflectance variability was not totally random as a function of the wavelength. The methods employed can be useful in the evaluation of color variability in industrial paint application processes.

  8. Calibration of Modulation Transfer Function of Surface Profilometers with 1D and 2D Binary Pseudo-random Array Standards

    International Nuclear Information System (INIS)

    Yashchuk, Valeriy V.; McKinney, Wayne R.; Takacs, Peter Z.

    2008-01-01

    We suggest and describe the use of a binary pseudo-random grating as a standard test surface for calibration of the modulation transfer function of microscopes. Results from calibration of a MicromapTM-570 interferometric microscope are presented.

  9. Enhanced Single Seed Trait Predictions in Soybean (Glycine max) and Robust Calibration Model Transfer with Near-Infrared Reflectance Spectroscopy.

    Science.gov (United States)

    Hacisalihoglu, Gokhan; Gustin, Jeffery L; Louisma, Jean; Armstrong, Paul; Peter, Gary F; Walker, Alejandro R; Settles, A Mark

    2016-02-10

    Single seed near-infrared reflectance (NIR) spectroscopy predicts soybean (Glycine max) seed quality traits of moisture, oil, and protein. We tested the accuracy of transferring calibrations between different single seed NIR analyzers of the same design by collecting NIR spectra and analytical trait data for globally diverse soybean germplasm. X-ray microcomputed tomography (μCT) was used to collect seed density and shape traits to enhance the number of soybean traits that can be predicted from single seed NIR. Partial least-squares (PLS) regression gave accurate predictive models for oil, weight, volume, protein, and maximal cross-sectional area of the seed. PLS models for width, length, and density were not predictive. Although principal component analysis (PCA) of the NIR spectra showed that black seed coat color had significant signal, excluding black seeds from the calibrations did not impact model accuracies. Calibrations for oil and protein developed in this study as well as earlier calibrations for a separate NIR analyzer of the same design were used to test the ability to transfer PLS regressions between platforms. PLS models built from data collected on one NIR analyzer had minimal differences in accuracy when applied to spectra collected from a sister device. Model transfer was more robust when spectra were trimmed from 910 to 1679 nm to 955-1635 nm due to divergence of edge wavelengths between the two devices. The ability to transfer calibrations between similar single seed NIR spectrometers facilitates broader adoption of this high-throughput, nondestructive, seed phenotyping technology.

  10. Spectrally adjusted surface reflectance and its dependence with NDVI for Landsat and Sentinel 2

    Science.gov (United States)

    Villaescusa, J. L.; Franch, B.; Roger, J. C.; Vermote, E.; Justice, C. O.

    2017-12-01

    Cross-calibration between sensors is necessary to bring measurements to a common radiometric scale; it allows a more complete monitoring of land surface processes and enhances data continuity and harmonization. However, differences in the Relative Spectral Response (RSR) of sensors generate uncertainties in the process (Teillet et al., 2004). For this reason, compensating for these differences is of great importance and can be achieved by using a spectral band adjustment factor (SBAF), which establishes a relationship between two spectrally adjusted bands. Nonetheless, this relationship has been shown to depend greatly on the surface's NDVI (Trishchenko et al., 2002) and therefore needs to be corrected. In this work, we use the Sentinel 2 and Landsat sensor's RSRs for both the Red and NIR bands to find the most accurate metric towards performing said relationship, and use surface reflectance spectral libraries with a wide variety of classes that include NDVI values ranging from -0.1 to 1 to analyze its dependence. We compute a quadratic fit of the metric used vs the surface's NDVI and propose an adjusted correction equation dependent on the NDVI value for both bands of all Landsat and Sentinel 2 sensors. Key words: Radiometric calibration, RSR, Spectral Adjustment, Landsat, Sentinel 2.

  11. Design and calibration of a scanning tunneling microscope for large machined surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Grigg, D.A.; Russell, P.E.; Dow, T.A.

    1988-12-01

    During the last year the large sample STM has been designed, built and used for the observation of several different samples. Calibration of the scanner for prope dimensional interpretation of surface features has been a chief concern, as well as corrections for non-linear effects such as hysteresis during scans. Several procedures used in calibration and correction of piezoelectric scanners used in the laboratorys STMs are described.

  12. Influence of composition and roughness on the pigment mapping of paintings using mid-infrared fiberoptics reflectance spectroscopy (mid-IR FORS) and multivariate calibration.

    Science.gov (United States)

    Sessa, Clarimma; Bagán, Héctor; García, Jose Francisco

    2014-10-01

    Mid-infrared fiberoptics reflectance spectroscopy (mid-IR FORS) is a very interesting technique for artwork characterization purposes. However, the fact that the spectra obtained are a mixture of surface (specular) and volume (diffuse) reflection is a significant drawback. The physical and chemical features of the artwork surface may produce distortions in the spectra that hinder comparison with reference databases acquired in transmission mode. Several studies attempted to understand the influence of the different variables and propose procedures to improve the interpretation of the spectra. This article is focused on the application of mid-IR FORS and multivariate calibration to the analysis of easel paintings. The objectives are the evaluation of the influence of the surface roughness on the spectra, the influence of the matrix composition for the classification of unknown spectra, and the capability of obtaining pigment composition mappings. A first evaluation of a fast procedure for spectra management and pigment discrimination is discussed. The results demonstrate the capability of multivariate methods, principal component analysis (PCA), and partial least squares discrimination analysis (PLS-DA), to model the distortions of the reflectance spectra and to delimitate and discriminate areas of uniform composition. The roughness of the painting surface is found to be an important factor affecting the shape and relative intensity of the spectra. A mapping of the major pigments of a painting is possible using mid-IR FORS and PLS-DA when the calibration set is a palette that includes the potential pigments present in the artwork mixed with the appropriate binder and that shows the different paint textures.

  13. Application of anti-reflection structures on curved surfaces

    Science.gov (United States)

    Yamamoto, Kazuya; Yamamoto, Takeshi; Takaoka, Toshimitsu; Seigo, Masafumi; Kitagawa, Seiichiro

    2012-02-01

    Conventional lens manufacturing is accomplished by injection molding followed by application of a thin film anti-reflection coating. This requires several production steps, each with the associated constraints. Here we report a technique for production of injection molded lenses with conical sub-wavelength grating anti-reflection structures. While similar structures have been made in the past, our technique allows the sub-wavelength structure to be created on curved surfaces during the injection molding process, reducing the number of steps in the manufacturing process. The advantage of this new technology is that anti-reflection function is created without any additional process(es) conventionally required but by a single injection molding process to make lens normally, through which substantial cost saving will be achieved.

  14. Continuous Calibration Improvement in Solar Reflective Bands: Landsat 5 Through Landsat 8

    Science.gov (United States)

    Mishra, Nischal; Helder, Dennis; Barsi, Julia; Markham, Brian

    2016-01-01

    Launched in February 2013, the Operational Land Imager (OLI) on-board Landsat 8 continues to perform exceedingly well and provides high science quality data globally. Several design enhancements have been made in the OLI instrument relative to prior Landsat instruments: pushbroom imaging which provides substantially improved Signal-to-Noise Ratio (SNR), spectral bandpasses refinement to avoid atmospheric absorption features, 12 bit data resolution to provide a larger dynamic range that limits the saturation level, a set of well-designed onboard calibrators to monitor the stability of the sensor. Some of these changes such as refinements in spectral bandpasses compared to earlier Landsats and well-designed on-board calibrator have a direct impact on the improved radiometric calibration performance of the instrument from both the stability of the response and the ability to track the changes. The on-board calibrator lamps and diffusers indicate that the instrument drift is generally less than 0.1% per year across the bands. The refined bandpasses of the OLI indicate that temporal uncertainty of better than 0.5% is possible when the instrument is trended over vicarious targets such as Pseudo Invariant Calibration Sites (PICS), a level of precision that was never achieved with the earlier Landsat instruments. The stability measurements indicated by on-board calibrators and PICS agree much better compared to the earlier Landsats, which is very encouraging and bodes well for the future Landsat missions too.

  15. Implementation of solar-reflective surfaces: Materials and utility programs

    Energy Technology Data Exchange (ETDEWEB)

    Bretz, S.; Akbari, H.; Rosenfeld, A.; Taha, H.

    1992-06-01

    This report focuses on implementation issues for using solar-reflective surfaces to cool urban heat islands, with specific examples for Sacramento, California. Advantages of solar-reflective surfaces for reducing energy use are: (1) they are cost-effective if albedo is increased during routine maintenance; (2) the energy savings coincide with peak demand for power; (3) there are positive effects on environmental quality; and (4) the white materials have a long service life. Important considerations when choosing materials for mitigating heat islands are identified as albedo, emissivity, durability, cost, pollution and appearance. There is a potential for increasing urban albedo in Sacramento by an additional 18%. Of residential roofs, we estimate that asphalt shingle and modified bitumen cover the largest area, and that built-up roofing and modified bitumen cover the largest area of commercial buildings. For all of these roof types, albedo may be increased at the time of re-roofing without any additional cost. When a roof is repaired, a solar-reflective roof coating may be applied to significantly increase albedo and extend the life of the root Although a coating may be cost-effective if applied to a new roof following installation or to an older roof following repair, it is not cost-effective if the coating is applied only to save energy. Solar-reflective pavement may be cost-effective if the albedo change is included in the routine resurfacing schedule. Cost-effective options for producing light-colored pavement may include: (1) asphalt concrete, if white aggregate is locally available; (2) concrete overlays; and (3) newly developed white binders and aggregate. Another option may be hot-rolled asphalt, with white chippings. Utilities could promote solar-reflective surfaces through advertisement, educational programs and cost-sharing of road resurfacing.

  16. Asteroid surface materials: mineralogical characterizations from reflectance spectra

    International Nuclear Information System (INIS)

    Gaffey, M.J.; McCord, T.B.

    1978-01-01

    The interpretation of diagnostic parameters in the spectral reflectance data for asteroids provides a means of characterizing the mineralogy and petrology of asteroid surface materials. An interpretive technique based on a quantitative understanding of the functional relationship between the optical properties of a mineral assemblage and its mineralogy, petrology and chemistry can provide a considerably more sophisticated characterization of a single material than any matching or classification technique for those objects bright enough to allow spectral reflectance measurements. Albedos derived from radiometry and polarization data for individual asteroids can be used with spectral data to establish the spectral albedo, to define the optical density of the surface material and, in general to constrain mineralogical interpretations. (Auth.)

  17. Calibration facilities of airborne, surface and borehole gamma ray spectrometric survey systems

    International Nuclear Information System (INIS)

    Sarma, C.V.R.; Raghuwanshi, S.S.; Sreehari, R.; Johri, N.K.

    2009-01-01

    The gamma-ray spectrometric surveys for uranium exploration are based upon the detection of gamma-rays emitted by the primordial radio nuclides of Uranium (Bi-214), Thorium (Tl-208) and K-40. However, the instrumentation with gamma radiation detectors for surface, airborne, borehole surveys requires to be calibrated for processing of field acquired data. Various calibration procedures are being adopted for this purpose in Atomic Minerals Directorate for Exploration and Research in India and elsewhere in the world. The airborne and portable gamma-ray spectrometric survey systems are calibrated on indigenously constructed and suitably spiked concrete calibration pads at the Civil Airport at Nagpur, India over very low activity zone of Deccan traps. Using these pads sensitivities and Compton scattering factors are computed for these systems. For the calibration of gamma-ray borehole logging probes, concretized boreholes have been constructed at premises of AMD Headquarters Hyderabad which are called the primary standards. The concentrations of these standards and results found for the sensitivities of different probes and systems are given in Table 1 thru Table 5. These calibration standards at Hyderabad and Nagpur are now the National facilities and are being constantly used for calibration purposes not only for the gamma ray spectrometers designed by AMD, but also for the imported gamma ray spectrometric systems acquired by various other organizations in India. This paper describes the details of these calibration facilities. There are two more calibration facilities for airborne gamma-ray spectrometric survey systems which are located at Devarakonda, A.P. and Mahalarbadi in Maharashtra, The concentrations of U, Th, K of Devarakonda Test Strip, A.P. are given in Table 2. (author)

  18. Calibration of a distributed hydrological model using satellite data of land surface temperature

    Science.gov (United States)

    Corbari, Chiara; Mancini, Marco; Ravazzani, Giovanni

    2013-04-01

    Calibration and validation of distributed models at basin scale generally refer to external variables, which are integrated catchment model outputs, and usually depend on the comparison between simulated and observed discharges at the available rivers cross sections, which are usually very few. However distributed models allow an internal validation due to their intrinsic structure, so that internal processes and variables of the model can be controlled in each cell of the domain. In particular this work investigates the potentiality to control evapotranspiration and its spatial and temporal variability through the detection of land surface temperature (LST) from satellite remote sensing. This study proposes a methodology for the calibration of distributed hydrological models at basin scale using remote sensing data of land surface temperature. The distributed energy water balance model, Flash-flood Event-based Spatially-distributed rainfall-runoff Transformation - Energy Water Balance model (FEST-EWB) will be calibrated in the Upper Po river basin (Italy) closed at the river cross section of Ponte della Becca with a total catchment area of about 38000 km2. The model algorithm solves the system of energy and mass balances in term of the representative pixel equilibrium temperature (RET) that governs the fluxes of energy and mass over the basin domain. This equilibrium surface temperature, which is a critical model state variable, is comparable to the land surface temperature (LST) from satellite. So a pixel to pixel semi-automatic calibration procedure of soil and vegetation parameter is presented through the comparison between the model internal state variable RET and the remotely observed LST. A similar calibration procedure will also be applied performing the traditional calibration using only discharge measurements. 260 diurnal and nocturne LST MODIS products are compared with FEST-EWB land surface temperature over the 11 years of simulation from 2000 to 2010

  19. Near Surface Seismic Reflection Imaging: Great Potential Under Critical Eye

    Science.gov (United States)

    Miller, R. D.; Peterie, S.; Judy, B. E.

    2014-12-01

    Seismic-reflection imaging has long been a mainstay in the oil and gas exploration community with mind boggling advancements in just the last decade, but its application to engineering, environmental, and groundwater problems has not seen the same level of utilization. A great deal of the problem lies in the many assumptions that are valid for deep exploration that are violated in the very complex near surface. Large channel systems with acquisition geometries conducive for both deep and shallow targets are many times assumed to be capable of extending the imaging depth window. In reality, constraints of the source and sensor/recording systems must be considered, where large powerful sources are needed to image exploration depths while low-energy, high-frequency sources are required for the shallow and thin targets in the near surface. Attempts to make one size fit all will result in artifacts that result in bogus images and characterizations in the shallow subsurface.Narrow optimum offsets, highly attenuative materials, extreme velocity variability, wavefield interference, and low signal-to-noise ratios provide an ideal breeding ground for the generation of artifacts on near-surface seismic-reflection data. With the cost of shallow reflection data being so high relative to other geophysical methods and invasive sampling, sometimes a single failure can hinder the growth in the use of the method. The method is extremely powerful and has the potential to provide vast quantities of information critical to understand the distributed hydrogeological and biogeochemical processes that elude borehole investigations. It is imperative that data be acquired in its rawest possible form and be processed with an eye to each operation. Cost savings sometimes result in one-size-fits-all acquisition and automated processing flows. Attention to detail and following signal from origination to characterization is essential.

  20. Assessment of SNPP VIIRS VIS NIR Radiometric Calibration Stability Using Aqua MODIS and Invariant Surface Targets

    Science.gov (United States)

    Wu, Aisheng; Xiong, Xiaoxiong; Cao, Changyong; Chiang, Kwo-Fu

    2016-01-01

    The first Visible Infrared Imaging Radiometer Suite (VIIRS) is onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite. As a primary sensor, it collects imagery and radiometric measurements of the land, atmosphere, cryosphere, and oceans in the spectral regions from visible (VIS) to long-wave infrared. NASA's National Polar-orbiting Partnership (NPP) VIIRS Characterization Support Team has been actively involved in the VIIRS radiometric and geometric calibration to support its Science Team Principal Investigators for their independent quality assessment of VIIRS Environmental Data Records. This paper presents the performance assessment of the radiometric calibration stability of the VIIRS VIS and NIR spectral bands using measurements from SNPP VIIRS and Aqua MODIS simultaneous nadir overpasses and over the invariant surface targets at the Libya-4 desert and Antarctic Dome Concordia snow sites. The VIIRS sensor data records (SDRs) used in this paper are reprocessed by the NASA SNPP Land Product Evaluation and Analysis Tool Element. This paper shows that the reprocessed VIIRS SDRs have been consistently calibrated from the beginning of the mission, and the calibration stability is similar to or better than MODIS. Results from different approaches indicate that the calibrations of the VIIRS VIS and NIR spectral bands are maintained to be stable to within 1% over the first three-year mission. The absolute calibration differences between VIIRS and MODIS are within 2%, with an exception for the 0.865-m band, after correction of their spectral response differences.

  1. Micro reflectance difference techniques: Optical probes for surface exploration

    Energy Technology Data Exchange (ETDEWEB)

    Lastras-Martinez, L.F.; Del Pozo-Zamudio, O.; Herrera-Jasso, R.; Ulloa-Castillo, N.A.; Balderas-Navarro, R.E.; Ortega-Gallegos, J.; Lastras-Martinez, A. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi, S.L.P. (Mexico)

    2012-06-15

    Micro reflectance difference spectroscopy ({mu}-RDS) is a promising tool for the in-situ and ex-situ characterization of semiconductors surfaces and interfaces. We discuss and compare two different approaches used to measure {mu}-RD spectra. One is based on a charge-coupled device (CCD) camera, while the other uses a laser and a XY translation stage. To show the performance of these systems, we have measured surface optical anisotropies of GaSb(001) sample on which anisotropic strains have been generated by preferential mechanical polishing along [110] and [1 anti 10] directions. The spectrometers are complementary and the selection of one of them depends on the sample to be investigated and on experimental conditions. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Assessment of polarization correction impact on the calibration of Terra MODIS reflective solar bands

    Science.gov (United States)

    Wu, Aisheng; Angal, Amit; Geng, Xu; Xiong, Xiaoxiong

    2017-09-01

    The Moderate-Resolution Imaging Spectroradiometer (MODIS), launched in 1999 on Terra and 2002 on Aqua spacecraft respectively, is a scanning radiometer that covers a wavelength range from 0.4 μm to 14.4 μm and scans the Earth over an angular range from -55° to +55°. After a few years in the Terra mission, it became extremely challenging to characterize the changes in the sensor gain and response versus scan angle (RVS) at short wavelengths due to significant degradation and increased polarization sensitivity. To better characterize the system-level degradation, the MODIS Characterization Support Team (MCST) developed an enhanced approach in Collection-6 (C6) L1B algorithm by supplementing the on-board calibration data with the Earth-scene response trends at various scan angles obtained from the pseudo-invariant desert sites. However, the trends at short wavelengths experienced significant impact due to the increased polarization sensitivity, especially at the end of scan. In this study, a polarization correction algorithm developed by MCST is applied to the Terra MODIS RSB response trends obtained from the desert sites. The trends after polarization correction are used to derive the gain and RVS based on the existing MODIS C6 calibration algorithm. Impact of the polarization correction is examined for gain, RVS and their fitting uncertainties over the entire mission. The results of this study provide useful information on how to further improve accuracy and stability of the calibrated L1B product.

  3. Review on common calibration and measuremnt practises for mesuring free form surface on CMMs

    DEFF Research Database (Denmark)

    Savio, Enrico; De Chiffre, Leonardo

    The present review outlines the state of the art of the traceability of measuring free form surfaces on coordinate measuring machines (CMMs). A general introduction to free from surfaces and to the way free form surfaces are inspected in industry at present is given.and some problems regarding...... the traceability of measuring of free form surfaces on CMMs outlined. A newly developed procedure for performance verification on CMMs with respect to free form measurements is described, and some investigations regarding this method are reviewed. The investigations are concerned with two new tests, the Spiral...... Test and the Cylinder Test developed as a coorperation between the University of Padova and the Technical University of Denmark. Experiments conducted by means of calibrated objects and CAD models created in an independent and external system, using calibrated dimensions are described. The experiments...

  4. Surface refraction of sound waves affects calibration of three-dimensional ultrasound.

    Science.gov (United States)

    Ballhausen, Hendrik; Ballhausen, Bianca Désirée; Lachaine, Martin; Li, Minglun; Parodi, Katia; Belka, Claus; Reiner, Michael

    2015-05-27

    Three-dimensional ultrasound (3D-US) is used in planning and treatment during external beam radiotherapy. The accuracy of the technique depends not only on the achievable image quality in clinical routine, but also on technical limitations of achievable precision during calibration. Refraction of ultrasound waves is a known source for geometric distortion, but such an effect was not expected in homogenous calibration phantoms. However, in this paper we demonstrate that the discontinuity of the refraction index at the phantom surface may affect the calibration unless the ultrasound probe is perfectly perpendicular to the phantom. A calibration phantom was repeatedly scanned with a 3D-US system (Elekta Clarity) by three independent observers. The ultrasound probe was moved horizontally at a fixed angle in the sagittal plane. The resulting wedge shaped volume between probe and phantom was filled with water to couple in the ultrasound waves. Because the speed of sound in water was smaller than the speed of sound in Zerdine, the main component of the phantom, the angle of the ultrasound waves inside the phantom increased. This caused an apparent shift in the calibration features which was recorded as a function of the impeding angle. To confirm the magnitude and temperature dependence, the experiment was repeated by two of the observers with a mixture of ice and water at 0 °C and with thermalized tap water at 21 °C room temperature. During the first series of measurements, a linear dependency of the displacements dx of the calibration features on the angle α of the ultrasound probe was observed. The three observers recorded significantly nonzero (p sound of 1,402 m/s at the melting point of ice. At 21 °C, slopes of 0.11 and 0.12 mm/° were recorded in agreement with the first experiment at about room temperature. The difference to the theoretical expectation of 0.07 mm/° was not significant (p = 0.09). The surface refraction of sound waves my affect the

  5. Self-calibrated dynamical optical biochip system using surface plasmon resonance imaging: application to genotyping

    Science.gov (United States)

    Hottin, Jérôme; Moreau, Julien; Spadavecchia, Jolanda; Bellemain, Alain; Lecerf, Laure; Goossens, Michel; Canva, Michael

    2008-04-01

    The present paper summarizes some of our work in the field of genetic diagnosis using Surface Plasmon Resonance Imaging. The optical setup and its capability are presented, as well as the gold surface functionalization used. Results obtained with oligonucleotides targets, specific to Cystic Fibrosis disease, in high and low concentration are shown. The self-calibration method we have developed to reduce data dispersion in genetic diagnosis applications is described.

  6. On-Orbit Performance and Calibration Improvements For the Reflective Solar Bands of Terra and Aqua MODIS

    Science.gov (United States)

    Angal, Amit; Xiong, Xiaoxiong; Wu, Aisheng; Chen, Hongda; Geng, Xu; Link, Daniel; Li, Yonghong; Wald, Andrew; Brinkmann, Jake

    2016-01-01

    Moderate Resolution Imaging Spectroradiometer (MODIS) is the keystone instrument for NASAs EOS Terra and Aqua missions, designed to extend and improve heritage sensor measurements and data records of the land, oceans and atmosphere. The reflective solar bands (RSB) of MODIS covering wavelengths from 0.41 micrometers to 2.2 micrometers, are calibrated on-orbit using a solar diffuser (SD), with its on-orbit bi-directional reflectance factor (BRF) changes tracked using a solar diffuser stability monitor (SDSM). MODIS is a scanning radiometer using a two-sided paddle-wheel mirror to collect earth view (EV) data over a range of (+/-)55 deg. off instrument nadir. In addition to the solar calibration provided by the SD and SDSM system, lunar observations at nearly constant phase angles are regularly scheduled to monitor the RSB calibration stability. For both Terra and Aqua MODIS, the SD and lunar observations are used together to track the on-orbit changes of RSB response versus scan angle (RVS) as the SD and SV port are viewed at different angles of incidence (AOI) on the scan mirror. The MODIS Level 1B (L1B) Collection 6 (C6) algorithm incorporated several enhancements over its predecessor Collection 5 (C5) algorithm. A notable improvement was the use of the earth-view (EV) response trends from pseudo-invariant desert targets to characterize the on-orbit RVS for select RSB (Terra bands 1-4, 8, 9 and Aqua bands 8, 9) and the time, AOI, and wavelength-dependent uncertainty. The MODIS Characterization Support Team (MCST) has been maintaining and enhancing the C6 algorithm since its first update in November, 2011 for Aqua MODIS, and February, 2012 for Terra MODIS. Several calibration improvements have been incorporated that include extending the EV-based RVS approach to other RSB, additional correction for SD degradation at SWIR wavelengths, and alternative approaches for on-orbit RVS characterization. In addition to the on-orbit performance of the MODIS RSB, this paper

  7. Contact-free calibration of an asymmetric multi-layer interferometer for the surface force balance

    Science.gov (United States)

    Balabajew, Marco; van Engers, Christian D.; Perkin, Susan

    2017-12-01

    The Surface Force Balance (SFB, also known as Surface Force Apparatus, SFA) has provided important insights into many phenomena within the field of colloid and interface science. The technique relies on using white light interferometry to measure the distance between surfaces with sub-nanometer resolution. Up until now, the determination of the distance between the surfaces required a so-called "contact calibration," an invasive procedure during which the surfaces are brought into mechanical contact. This requirement for a contact calibration limits the range of experimental systems that can be investigated with SFB, for example, it precludes experiments with substrates that would be irreversibly modified or damaged by mechanical contact. Here we present a non-invasive method to measure absolute distances without performing a contact calibration. The method can be used for both "symmetric" and "asymmetric" systems. We foresee many applications for this general approach including, most immediately, experiments using single layer graphene electrodes in the SFB which may be damaged when brought into mechanical contact.

  8. CLARREO: Reference Inter-Calibration on Orbit With Reflected Solar Spectrometer

    Science.gov (United States)

    Lukashin, C.; Roithmayr, C.; Currey, C.; Wielicki, B.; Goldin, D.; Sun, W.

    2016-01-01

    The CLARREO approach for reference intercalibration is based on obtaining coincident highly accurate spectral reflectance and reflected radiance measurements, and establish an on-orbit reference for existing Earth viewing reflected solar radiation sensors: CERES and VIIRS on JPSS satellites, AVHRR and follow-on imagers on MetOp, and imagers on GEO platforms. The mission goal is to be able to provide CLARREO RS reference observations that are matched in space, time, and viewing angles with measurements from the aforementioned instruments, with sampling sufficient to overcome the random error sources from imperfect data matching and instrument noise. The intercalibration method is to monitor over time changes in targeted sensor response function parameters: effective offset, gain, nonlinearity, spectral degradation, and sensitivity to polarization of optics.

  9. Interferometry of a reflective axicon surface with a small cone angle using an optical inner surface

    Science.gov (United States)

    Gao, Huimin; Zhang, Xiaodong; Fang, Fengzhou

    2017-09-01

    Reflective axicons, widely used in optical alignment and Bessel-Gauss beam generation, require a highly accurate cone angle and surface metrology. However, current methods focus on the cone angle measurement and it is still difficult to measure the surface of a reflective axicon with a small cone angle. An interferometer measurement method using an optical inner surface is proposed to obtain the surface and cone angle simultaneously. The optical axis of the axicon and the optical inner surface should align together and be parallel to the beam light from the interferometer. The interference fringe would be obtained by the optical system consisting of the axicon and the optical inner surface. The theoretical model is established and analyzed through ray tracing theory, and is verified by optical simulation software. Fabrication errors in the axicon and the inner surface, and misalignment of the measurement setup are investigated systematically and separated in the measurement process. In the experiments, the reflective axicon with a cone angle of about 90° was measured by the proposed method, the results of which show good agreement with a stylus profiler (Taylor-Hobson PGI 3D) in cone angle trend and generatrix error. Experimental results prove the feasibility of the proposed method. This economical and effective method can be widely used with all types of reflective axicons, and it can obtain the surface error map of the axicon as well as the inner cylinder at the same time. The uncertainty and resolution of the proposed method is based on the performance of the interferometer. The uncertainty of alignment angle errors is less than 10-10 rad; the lateral resolution is 53.8 µm.

  10. Interferometry of a reflective axicon surface with a small cone angle using an optical inner surface

    International Nuclear Information System (INIS)

    Gao, Huimin; Zhang, Xiaodong; Fang, Fengzhou

    2017-01-01

    Reflective axicons, widely used in optical alignment and Bessel–Gauss beam generation, require a highly accurate cone angle and surface metrology. However, current methods focus on the cone angle measurement and it is still difficult to measure the surface of a reflective axicon with a small cone angle. An interferometer measurement method using an optical inner surface is proposed to obtain the surface and cone angle simultaneously. The optical axis of the axicon and the optical inner surface should align together and be parallel to the beam light from the interferometer. The interference fringe would be obtained by the optical system consisting of the axicon and the optical inner surface. The theoretical model is established and analyzed through ray tracing theory, and is verified by optical simulation software. Fabrication errors in the axicon and the inner surface, and misalignment of the measurement setup are investigated systematically and separated in the measurement process. In the experiments, the reflective axicon with a cone angle of about 90° was measured by the proposed method, the results of which show good agreement with a stylus profiler (Taylor-Hobson PGI 3D) in cone angle trend and generatrix error. Experimental results prove the feasibility of the proposed method. This economical and effective method can be widely used with all types of reflective axicons, and it can obtain the surface error map of the axicon as well as the inner cylinder at the same time. The uncertainty and resolution of the proposed method is based on the performance of the interferometer. The uncertainty of alignment angle errors is less than 10 −10 rad; the lateral resolution is 53.8 µ m. (paper)

  11. MODIS/Terra Surface Reflectance 8-Day L3 Global 250m SIN Grid V005

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  12. MODIS/Terra Surface Reflectance 8-Day L3 Global 500m SIN Grid V005

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  13. MODIS/Terra Surface Reflectance Daily L2G Global 250m SIN Grid V005

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  14. Collection and corrections of oblique multiangle hyperspectral bidirectional reflectance imagery of the water surface

    Science.gov (United States)

    Bostater, Charles R.; Oney, Taylor S.

    2017-10-01

    Hyperspectral images of coastal waters in urbanized regions were collected from fixed platform locations. Surf zone imagery, images of shallow bays, lagoons and coastal waters are processed to produce bidirectional reflectance factor (BRF) signatures corrected for changing viewing angles. Angular changes as a function of pixel location within a scene are used to estimate changes in pixel size and ground sampling areas. Diffuse calibration targets collected simultaneously from within the image scene provides the necessary information for calculating BRF signatures of the water surface and shorelines. Automated scanning using a pushbroom hyperspectral sensor allows imagery to be collected on the order of one minute or less for different regions of interest. Imagery is then rectified and georeferenced using ground control points within nadir viewing multispectral imagery via image to image registration techniques. This paper demonstrates the above as well as presenting how spectra can be extracted along different directions in the imagery. The extraction of BRF spectra along track lines allows the application of derivative reflectance spectroscopy for estimating chlorophyll-a, dissolved organic matter and suspended matter concentrations at or near the water surface. Imagery is presented demonstrating the techniques to identify subsurface features and targets within the littoral and surf zones.

  15. Viscoelasticity evaluation of rubber by surface reflection of supersonic wave.

    Science.gov (United States)

    Omata, Nobuaki; Suga, Takahiro; Furusawa, Hirokazu; Urabe, Shinichi; Kondo, Takeru; Ni, Qing-Qing

    2006-12-22

    The main characteristic of rubber is a viscoelasticity. So it is important to research the characteristic of the viscoelasticity of the high frequency band for the friction between a rubber material and the hard one with roughness, for instance, the tire and the road. As for the measurement of the viscoelasticity of rubber, DMA (dynamic mechanical analysis) is general. However, some problems are pointed out to the measurement of the high frequency band by DMA. Then, we evaluated the viscoelasticity characteristic by the supersonic wave measurement. However, attenuation of rubber is large, and when the viscoelasticity is measured by the supersonic wave therefore, it is inconvenient and limited in a past method by means of bottom reflection. In this report, we tried the viscoelasticity evaluation by the method of using complex surface reflection coefficient and we compared with the friction coefficient under wide-range friction velocity. As a result, some relationships had been found for two properties. We report the result that character of viscoelasticity of rubber was comparable to friction coefficient.

  16. Mars analog minerals' spectral reflectance characteristics under Martian surface conditions

    Science.gov (United States)

    Poitras, J. T.; Cloutis, E. A.; Salvatore, M. R.; Mertzman, S. A.; Applin, D. M.; Mann, P.

    2018-05-01

    We investigated the spectral reflectance properties of minerals under a simulated Martian environment. Twenty-eight different hydrated or hydroxylated phases of carbonates, sulfates, and silica minerals were selected based on past detection on Mars through spectral remote sensing data. Samples were ground and dry sieved to Mars, only losing adsorbed H2O while maintaining their diagnostic spectral features. Sulfates were less stable, often with shifts in the band position of the SO, Fe, and OH absorption features. Silicas displayed spectral shifts related to SiOH and hydration state of the mineral surface, while diagnostic bands for quartz were stable. Previous detection of carbonate minerals based on 2.3-2.5 μm and 3.4-3.9 μm features appears to be consistent with our results. Sulfate mineral detection is more questionable since there can be shifts in band position related to SO4. The loss of the 0.43 μm Fe3+ band in many of the sulfates indicate that there are fewer potential candidates for Fe3+ sulfates to permanently exist on the Martian surface based on this band. The gypsum sample changed phase to basanite during desiccation as demonstrated by both reflectance and XRD. Silica on Mars has been detected using band depth ratio at 1.91 and 1.96 μm and band minimum position of the 1.4 μm feature, and the properties are also used to determine their age. This technique continues to be useful for positive silica identifications, however, silica age appears to be less consistent with our laboratory data. These results will be useful in spectral libraries for characterizing Martian remote sensed data.

  17. X-Ray Reflectivity from the Surface of a Liquid Crystal:

    DEFF Research Database (Denmark)

    Pershan, P.S.; Als-Nielsen, Jens Aage

    1984-01-01

    X-ray reflectivity from the surface of a nematic liquid crystal is interpreted as the coherent superposition of Fresnel reflection from the surface and Bragg reflection from smectic order induced by the surface. Angular dependence of the Fresnel effect yields information on surface structure....... Measurement of the intensity of diffuse critical scattering relative to the Fresnel reflection yields the absolute value of the critical part of the density-density correlation function....

  18. Radiometric calibration of the reflective bands of NS001-Thematic Mapper Simulator (TMS) and modular multispectral radiometers (MMR)

    Science.gov (United States)

    Markham, Brian L.; Wood, Frank M., Jr.; Ahmad, Suraiya P.

    1988-01-01

    The NS001 Thematic Mapper Simulator scanner (TMS) and several modular multispectral radiometers (MMRs) are among the primary instruments used in the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE). The NS001 has a continuously variable gain setting. Calibration of the NS001 data is influenced by drift in the dark current level of up to six counts during a mirror scan at typical gain settings. The MMR instruments are being used in their 1 deg FOV configuration on the helicopter and 15 deg FOV on the ground.

  19. Standard test method for calibration of surface/stress measuring devices

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    Return to Contents page 1.1 This test method covers calibration or verification of calibration, or both, of surface-stress measuring devices used to measure stress in annealed and heat-strengthened or tempered glass using polariscopic or refractometry based principles. 1.2 This test method is nondestructive. 1.3 This test method uses transmitted light, and therefore, is applicable to light-transmitting glasses. 1.4 This test method is not applicable to chemically tempered glass. 1.5 Using the procedure described, surface stresses can be measured only on the “tin” side of float glass. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  20. Evaluation of the planar sources surface homogeneity used to instruments calibration

    Energy Technology Data Exchange (ETDEWEB)

    Vivolo, Vitor [Instituto de Pesquisas Energeticas e Nucleares, Comissao Nacional de Energia Nuclear/SP, C.P. 11049, CEP 05422-970 Sao Paulo (Brazil)], E-mail: vivolo@ipen.br; Penha Albuquerque Potiens, Maria da [Instituto de Pesquisas Energeticas e Nucleares, Comissao Nacional de Energia Nuclear/SP, C.P. 11049, CEP 05422-970 Sao Paulo (Brazil)], E-mail: mppalbu@ipen.br

    2010-04-15

    The surface homogeneity of planar sources used to calibrate contamination detectors is important considering that their dimensions are bigger than the most kind of detectors tested and the positioning in relation to the source may vary in each measurement. Using a special pancake detector the counting efficiency of alpha and beta sources was measured in several positioning covering all area of the sources. The {sup 14}C source showed the worse performance and the {sup 241}Am source showed the best behavior.

  1. An optimized calibration method for surface measurements with MOSFETs in shaped-beam radiosurgery.

    Science.gov (United States)

    Sors, A; Cassol, E; Latorzeff, I; Duthil, P; Sabatier, J; Lotterie, J A; Redon, A; Berry, I; Franceries, X

    2014-02-01

    Nowadays MOSFET dosimeters are widely used for dose verification in radiotherapy procedures. Although their sensitive area satisfies size requirements for small field dosimetry, their use in radiosurgery has rarely been reported. The aim of this study is to propose and optimize a calibration method to perform surface measurements in 6 MV shaped-beam radiosurgery for field sizes down to 18 × 18 mm(2). The effect of different parameters such as recovery time between 2 readings, batch uniformity and build-up cap attenuation was studied. Batch uniformity was found to be within 2% and isocenter dose attenuation due to the build-up cap over the MOSFET was near 2% irrespective of field size. Two sets of sensitivity coefficients (SC) were determined for TN-502RD MOSFET dosimeters using experimental and calculated calibration; the latter being developed using an inverse square law model. Validation measurements were performed on a realistic head phantom in irregular fields. MOSFET dose values obtained by applying either measured or calculated SC were compared. For calibration, optimal results were obtained for an inter-measurement time lapse of 5 min. We also found that fitting the SC values with the inverse square law reduced the number of measurements required for calibration. The study demonstrated that combining inverse square law and Sterling-Worthley formula resulted in an underestimation of up to 4% of the dose measured by MOSFETs for complex beam geometries. With the inverse square law, it is possible to reduce the number of measurements required for calibration for multiple field-SSD combinations. Our results suggested that MOSFETs are suitable sensors for dosimetry when used at the surface in shaped-beam radiosurgery down to 18 × 18 mm(2). Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  2. A framework for modeling connections between hydraulics, water surface roughness, and surface reflectance in open channel flows

    Science.gov (United States)

    Legleiter, Carl; Mobley, Curtis D.; Overstreet, Brandon

    2017-01-01

    This paper introduces a framework for examining connections between the flow field, the texture of the air-water interface, and the reflectance of the water surface and thus evaluating the potential to infer hydraulic information from remotely sensed observations of surface reflectance. We used a spatial correlation model describing water surface topography to illustrate the application of our framework. Nondimensional relations between model parameters and flow intensity were established based on a prior flume study. Expressing the model in the spatial frequency domain allowed us to use an efficient Fourier transform-based algorithm for simulating water surfaces. Realizations for both flume and field settings had water surface slope distributions positively correlated with velocity and water surface roughness. However, most surface facets were gently sloped and thus unlikely to yield strong specular reflections; the model exaggerated the extent of water surface features, leading to underestimation of facet slopes. A ray tracing algorithm indicated that reflectance was greatest when solar and view zenith angles were equal and the sensor scanned toward the Sun to capture specular reflections of the solar beam. Reflected energy was concentrated in a small portion of the sky, but rougher water surfaces reflected rays into a broader range of directions. Our framework facilitates flight planning to avoid surface-reflected radiance while mapping other river attributes, or to maximize this component to exploit relationships between hydraulics and surface reflectance. This initial analysis also highlighted the need for improved models of water surface topography in natural rivers.

  3. A framework for modeling connections between hydraulics, water surface roughness, and surface reflectance in open channel flows

    Science.gov (United States)

    Legleiter, Carl J.; Mobley, Curtis D.; Overstreet, Brandon T.

    2017-09-01

    This paper introduces a framework for examining connections between the flow field, the texture of the air-water interface, and the reflectance of the water surface and thus evaluating the potential to infer hydraulic information from remotely sensed observations of surface reflectance. We used a spatial correlation model describing water surface topography to illustrate the application of our framework. Nondimensional relations between model parameters and flow intensity were established based on a prior flume study. Expressing the model in the spatial frequency domain allowed us to use an efficient Fourier transform-based algorithm for simulating water surfaces. Realizations for both flume and field settings had water surface slope distributions positively correlated with velocity and water surface roughness. However, most surface facets were gently sloped and thus unlikely to yield strong specular reflections; the model exaggerated the extent of water surface features, leading to underestimation of facet slopes. A ray tracing algorithm indicated that reflectance was greatest when solar and view zenith angles were equal and the sensor scanned toward the Sun to capture specular reflections of the solar beam. Reflected energy was concentrated in a small portion of the sky, but rougher water surfaces reflected rays into a broader range of directions. Our framework facilitates flight planning to avoid surface-reflected radiance while mapping other river attributes, or to maximize this component to exploit relationships between hydraulics and surface reflectance. This initial analysis also highlighted the need for improved models of water surface topography in natural rivers.

  4. Airborne hyperspectral observations of surface and cloud directional reflectivity using a commercial digital camera

    Directory of Open Access Journals (Sweden)

    A. Ehrlich

    2012-04-01

    Full Text Available Spectral radiance measurements by a digital single-lens reflex camera were used to derive the directional reflectivity of clouds and different surfaces in the Arctic. The camera has been calibrated radiometrically and spectrally to provide accurate radiance measurements with high angular resolution. A comparison with spectral radiance measurements with the Spectral Modular Airborne Radiation measurement sysTem (SMART-Albedometer showed an agreement within the uncertainties of both instruments (6% for both. The directional reflectivity in terms of the hemispherical directional reflectance factor (HDRF was obtained for sea ice, ice-free ocean and clouds. The sea ice, with an albedo of ρ = 0.96 (at 530 nm wavelength, showed an almost isotropic HDRF, while sun glint was observed for the ocean HDRF (ρ = 0.12. For the cloud observations with ρ = 0.62, the cloudbow – a backscatter feature typically for scattering by liquid water droplets – was covered by the camera. For measurements above heterogeneous stratocumulus clouds, the required number of images to obtain a mean HDRF that clearly exhibits the cloudbow has been estimated at about 50 images (10 min flight time. A representation of the HDRF as a function of the scattering angle only reduces the image number to about 10 (2 min flight time.

    The measured cloud and ocean HDRF have been compared to radiative transfer simulations. The ocean HDRF simulated with the observed surface wind speed of 9 m s−1 agreed best with the measurements. For the cloud HDRF, the best agreement was obtained by a broad and weak cloudbow simulated with a cloud droplet effective radius of Reff = 4 μm. This value agrees with the particle sizes derived from in situ measurements and retrieved from the spectral radiance of the SMART-Albedometer.

  5. Cuban-Brazilian comparison of the calibration procedures for surface contamination monitors

    International Nuclear Information System (INIS)

    Salas, Gonzalo W.; Garcia, Jose A.T.; Ramos, Manoel M.O.

    2007-01-01

    The calibration laboratory of the CPHR, Centro de Proteccion e Higiene de las Radiaciones, is the only laboratory that performs calibrations of radiation protection instruments in Cuba. Recently they started a cooperation project with IAEA, code number CUB3002-01 with the task title 'Assuring and Demonstrating the safety of radioactive Waste Management'. Within the frame of this project they have a compromise to implement the calibration service for surface contamination monitors, for which they received instruments and sources. In 2006 the Laboratorio Nacional de Metrologia das Radiacoes Ionizantes (LNMRI) from the Instituto de Radioprotecao e Dosimetria, IRD/CNEN, was invited to perform a mission to CPHR in order to evaluate the level of implementation of the service trough the insertion of the service in the Quality Assurance System of their laboratory, and perform a comparison exercise to test the calibration method implemented. The results were evaluated by the methodology recommended in the ISO/IEC 43-1 standard. These results show that all values from both laboratories are comparable for most radionuclides except for Cl-36. The preliminary investigation about this situation is presented in the paper. (author)

  6. Reference-free total reflection X-ray fluorescence analysis of semiconductor surfaces with synchrotron radiation.

    Science.gov (United States)

    Beckhoff, Burkhard; Fliegauf, Rolf; Kolbe, Michael; Müller, Matthias; Weser, Jan; Ulm, Gerhard

    2007-10-15

    Total reflection X-ray fluorescence (TXRF) analysis is a well-established method to monitor lowest level contamination on semiconductor surfaces. Even light elements on a wafer surface can be excited effectively when using high-flux synchrotron radiation in the soft X-ray range. To meet current industrial requirements in nondestructive semiconductor analysis, the Physikalisch-Technische Bundesanstalt (PTB) operates dedicated instrumentation for analyzing light element contamination on wafer pieces as well as on 200- and 300-mm silicon wafer surfaces. This instrumentation is also suited for grazing incidence X-ray fluorescence analysis and conventional energy-dispersive X-ray fluorescence analysis of buried and surface nanolayered structures, respectively. The most prominent features are a high-vacuum load-lock combined with an equipment front end module and a UHV irradiation chamber with an electrostatic chuck mounted on an eight-axis manipulator. Here, the entire surface of a 200- or a 300-mm wafer can be scanned by monochromatized radiation provided by the plane grating monochromator beamline for undulator radiation in the PTB laboratory at the electron storage ring BESSY II. This beamline provides high spectral purity and high photon flux in the range of 0.078-1.86 keV. In addition, absolutely calibrated photodiodes and Si(Li) detectors are used to monitor the exciting radiant power respectively the fluorescence radiation. Furthermore, the footprint of the excitation radiation at the wafer surface is well-known due to beam profile recordings by a CCD during special operation conditions at BESSY II that allow for drastically reduced electron beam currents. Thus, all the requirements of completely reference-free quantitation of TXRF analysis are fulfilled and are to be presented in the present work. The perspectives to arrange for reference-free quantitation using X-ray tube-based, table-top TXRF analysis are also addressed.

  7. Land Surface Reflectance Retrieval from Hyperspectral Data Collected by an Unmanned Aerial Vehicle over the Baotou Test Site

    Science.gov (United States)

    Duan, Si-Bo; Li, Zhao-Liang; Tang, Bo-Hui; Wu, Hua; Ma, Lingling; Zhao, Enyu; Li, Chuanrong

    2013-01-01

    To evaluate the in-flight performance of a new hyperspectral sensor onboard an unmanned aerial vehicle (UAV-HYPER), a comprehensive field campaign was conducted over the Baotou test site in China on 3 September 2011. Several portable reference reflectance targets were deployed across the test site. The radiometric performance of the UAV-HYPER sensor was assessed in terms of signal-to-noise ratio (SNR) and the calibration accuracy. The SNR of the different bands of the UAV-HYPER sensor was estimated to be between approximately 5 and 120 over the homogeneous targets, and the linear response of the apparent reflectance ranged from approximately 0.05 to 0.45. The uniform and non-uniform Lambertian land surface reflectance was retrieved and validated using in situ measurements, with root mean square error (RMSE) of approximately 0.01–0.07 and relative RMSE of approximately 5%–12%. There were small discrepancies between the retrieved uniform and non-uniform Lambertian land surface reflectance over the homogeneous targets and under low aerosol optical depth (AOD) conditions (AOD = 0.18). However, these discrepancies must be taken into account when adjacent pixels had large land surface reflectance contrast and under high AOD conditions (e.g. AOD = 1.0). PMID:23785513

  8. Land surface reflectance retrieval from hyperspectral data collected by an unmanned aerial vehicle over the Baotou test site.

    Science.gov (United States)

    Duan, Si-Bo; Li, Zhao-Liang; Tang, Bo-Hui; Wu, Hua; Ma, Lingling; Zhao, Enyu; Li, Chuanrong

    2013-01-01

    To evaluate the in-flight performance of a new hyperspectral sensor onboard an unmanned aerial vehicle (UAV-HYPER), a comprehensive field campaign was conducted over the Baotou test site in China on 3 September 2011. Several portable reference reflectance targets were deployed across the test site. The radiometric performance of the UAV-HYPER sensor was assessed in terms of signal-to-noise ratio (SNR) and the calibration accuracy. The SNR of the different bands of the UAV-HYPER sensor was estimated to be between approximately 5 and 120 over the homogeneous targets, and the linear response of the apparent reflectance ranged from approximately 0.05 to 0.45. The uniform and non-uniform Lambertian land surface reflectance was retrieved and validated using in situ measurements, with root mean square error (RMSE) of approximately 0.01-0.07 and relative RMSE of approximately 5%-12%. There were small discrepancies between the retrieved uniform and non-uniform Lambertian land surface reflectance over the homogeneous targets and under low aerosol optical depth (AOD) conditions (AOD = 0.18). However, these discrepancies must be taken into account when adjacent pixels had large land surface reflectance contrast and under high AOD conditions (e.g. AOD = 1.0).

  9. Improved Aerosol Optical Thickness, Columnar Water Vapor, and Surface Reflectance Retrieval from Combined CASI and SASI Airborne Hyperspectral Sensors

    Directory of Open Access Journals (Sweden)

    Hang Yang

    2017-02-01

    Full Text Available An increasingly common requirement in remote sensing is the integration of hyperspectral data collected simultaneously from different sensors (and fore-optics operating across different wavelength ranges. Data from one module are often relied on to correct information in the other, such as aerosol optical thickness (AOT and columnar water vapor (CWV. This paper describes problems associated with this process and recommends an improved strategy for processing remote sensing data, collected from both visible to near-infrared and shortwave infrared modules, to retrieve accurate AOT, CWV, and surface reflectance values. This strategy includes a workflow for radiometric and spatial cross-calibration and a method to retrieve atmospheric parameters and surface reflectance based on a radiative transfer function. This method was tested using data collected with the Compact Airborne Spectrographic Imager (CASI and SWIR Airborne Spectrographic Imager (SASI from a site in Huailai County, Hebei Province, China. Various methods for retrieving AOT and CWV specific to this region were assessed. The results showed that retrieving AOT from the remote sensing data required establishing empirical relationships between 465.6 nm/659 nm and 2105 nm, augmented by ground-based reflectance validation data, and minimizing the merit function based on AOT@550 nm optimization. The paper also extends the second-order difference algorithm (SODA method using Powell’s methods to optimize CWV retrieval. The resulting CWV image has fewer residual surface features compared with the standard methods. The derived remote sensing surface reflectance correlated significantly with the ground spectra of comparable vegetation, cement road and soil targets. Therefore, the method proposed in this paper is reliable enough for integrated atmospheric correction and surface reflectance retrieval from hyperspectral remote sensing data. This study provides a good reference for surface

  10. Sensitivity analysis and development of calibration methodology for near-surface hydrogeology model of Laxemar

    International Nuclear Information System (INIS)

    Aneljung, Maria; Sassner, Mona; Gustafsson, Lars-Goeran

    2007-11-01

    This report describes modelling where the hydrological modelling system MIKE SHE has been used to describe surface hydrology, near-surface hydrogeology, advective transport mechanisms, and the contact between groundwater and surface water within the SKB site investigation area at Laxemar. In the MIKE SHE system, surface water flow is described with the one-dimensional modelling tool MIKE 11, which is fully and dynamically integrated with the groundwater flow module in MIKE SHE. In early 2008, a supplementary data set will be available and a process of updating, rebuilding and calibrating the MIKE SHE model based on this data set will start. Before the calibration on the new data begins, it is important to gather as much knowledge as possible on calibration methods, and to identify critical calibration parameters and areas within the model that require special attention. In this project, the MIKE SHE model has been further developed. The model area has been extended, and the present model also includes an updated bedrock model and a more detailed description of the surface stream network. The numerical model has been updated and optimized, especially regarding the modelling of evapotranspiration and the unsaturated zone, and the coupling between the surface stream network in MIKE 11 and the overland flow in MIKE SHE. An initial calibration has been made and a base case has been defined and evaluated. In connection with the calibration, the most important changes made in the model were the following: The evapotranspiration was reduced. The infiltration capacity was reduced. The hydraulic conductivities of the Quaternary deposits in the water-saturated part of the subsurface were reduced. Data from one surface water level monitoring station, four surface water discharge monitoring stations and 43 groundwater level monitoring stations (SSM series boreholes) have been used to evaluate and calibrate the model. The base case simulations showed a reasonable agreement

  11. A Harmonized Landsat-Sentinel-2 Surface Reflectance product: a resource for Agricultural Monitoring

    Science.gov (United States)

    Masek, J. G.; Claverie, M.; Ju, J.; Vermote, E.; Justice, C. O.

    2015-12-01

    The combination of Landsat and Sentinel-2 data offers a unique opportunity to observe globally the land every 2-3 days at medium (reflectance data from Landsat and Sentinel-2 missions and to deliver them to the community in a combined, seamless form. The HLS will be beneficial for global agricultural monitoring applications that require medium spatial resolution and weekly or more frequent observations. In particular, the provided opportunity to track crop phenology at the scale of individual fields will support detailed mapping of crop type and type-specific vegetation conditions. To create a compatible set of radiometric measurements, the HLS product relies on rigorous pre- and post-launch cross-calibration (Landsat-8 OLI and Sentinel-2 MSI) activities. The processing chain includes the following components: atmospheric correction, cloud/shadow masking, nadir BRDF-adjustment, spectral-adjustment, regridding, and temporal composite. The atmospheric correction and cloud masking is based on the OLI atmospheric correction developed at NASA-GSFC and has been adapted to the MSI data. The BRDF-adjustment is based on a disaggregation technique using MODIS-based BRDF coefficients. The technique has been evaluated using the multi-angular acquisition from the SPOT 4 and 5 (Take5) experiments. The spectral-adjustment relies on a linear regression that has been calibrated and evaluated using synthetic data and surface reflectance processed from a large number of hyperspectral EO-1 Hyperion scenes. Finally, significant effort is placed on product validation and evaluation. The delivered data set will include surface reflectance products at different levels: Using the native gridding, i.e. UTM, 30m for Landsat-8, and UTM, 10-20m for Sentinel-2 Using a common global gridding (Sinusoidal, 30m) Temporal composite (Sinusoidal, 30m, 5-day) During the first year of operation of Sentinel-2A, the HLS will be prototyped over a selection of 30 sites that includes some of the JECAM sites

  12. Improving the Ar I and II branching ratio calibration method: Monte Carlo simulations of effects from photon scattering/reflecting in hollow cathodes

    Science.gov (United States)

    Lawler, J. E.; Den Hartog, E. A.

    2018-03-01

    The Ar I and II branching ratio calibration method is discussed with the goal of improving the technique. This method of establishing a relative radiometric calibration is important in ongoing research to improve atomic transition probabilities for quantitative spectroscopy in astrophysics and other fields. Specific suggestions are presented along with Monte Carlo simulations of wavelength dependent effects from scattering/reflecting of photons in a hollow cathode.

  13. Variability of Surface Reflection Amplitudes of GPR Horn Antenna Depending on Distance between Antenna and Surface

    Directory of Open Access Journals (Sweden)

    Komačka Jozef

    2016-05-01

    Full Text Available The study focused on variability of surface reflections amplitudes of GPR horn antenna in relation to distance between an antenna and a surface is presented in the paper. The air-coupled antenna with the central frequency of 1 GHz was used in the investigation. Four types of surfaces (dry pavement, wet pavement, metal plate and composite layer from gypsum and wood were tested. The distance of antenna above the surfaces was changed in the range from 37.5 cm to 53.5 cm. The amplitudes of negative and positive peaks and their variability were analysed in relation to the distance of antenna above the surfaces. Moreover, the influence of changes in the peaks of negative and positive amplitudes on the total amplitudes was assessed. It was found out the amplitudes of negative peaks for all investigated surfaces were relatively consistent in the range from 40.5 cm to 48.5 cm and the moderate decline was identified in the case of amplitudes of positive peaks in the range of distances from 37.5 cm to 51.5 cm. This decline influences the tendency of total amplitudes. Based on the results of analysis it can be stated the distance of air-coupled antenna above the surface can influence the value of total amplitude and the differences depend on the type of surface.

  14. Miniaturized Laser-Induced Breakdown Spectroscopy for the in-situ analysis of the Martian surface: Calibration and quantification

    International Nuclear Information System (INIS)

    Rauschenbach, I.; Jessberger, E.K.; Pavlov, S.G.; Huebers, H.-W.

    2010-01-01

    We report on our ongoing studies to develop Laser-Induced Breakdown Spectroscopy (LIBS) for planetary surface missions to Mars and other planets and moons, like Jupiter's moon Europa or the Earth's moon. Since instruments for space missions are severely mass restricted, we are developing a light-weight miniaturized close-up LIBS instrument to be installed on a lander or rover for the in-situ geochemical analysis of planetary surface rocks and coarse fines. The total mass of the instrument will be ∼ 1 kg in flight configuration. Here we report on a systematic performance study of a LIBS instrument equipped with a prototype laser of 216 g total mass and an energy of 1.8 mJ. The LIBS measurements with the prototype laser and the comparative measurements with a regular 40 mJ laboratory laser were both performed under Martian atmospheric conditions. We calibrated 14 major and minor elements by analyzing 18 natural samples of certified composition. The calibration curves define the limits of detection that are > 5 ppm for the lab laser and > 400 ppm for the prototype laser, reflecting the different analyzed sample masses of ∼ 20 μg and ∼ 2 μg, respectively. To test the accuracy we compared the LIBS compositions, determined with both lasers, of Mars analogue rocks with certified or independently measured compositions and found agreements typically within 10-20%. In addition we verified that dust coverage is effectively removed from rock surfaces by the laser blast. Our study clearly demonstrates that a close-up LIBS instrument (spot size ∼ 50 μm) will decisively enhance the scientific output of planetary lander missions by providing a very large number of microscopic elemental analyses.

  15. Interactions of light with rough dielectric surfaces - Spectral reflectance and polarimetric properties

    Science.gov (United States)

    Yon, S. A.; Pieters, C. M.

    1988-01-01

    The nature of the interactions of visible and NIR radiation with the surfaces of rock and mineral samples was investigated by measuring the reflectance and the polarization properties of scattered and reflected light for slab samples of obsidian and fine-grained basalt, prepared to controlled surface roughness. It is shown that the degree to which radiation can penetrate a surface and then scatter back out, an essential criterion for mineralogic determinations based on reflectance spectra, depends not only upon the composition of the material, but also on its physical condition such as sample grain size and surface roughness. Comparison of the experimentally measured reflectance and polarization from smooth and rough slab materials with the predicted models indicates that single Fresnel reflections are responsible for the largest part of the reflected intensity resulting from interactions with the surfaces of dielectric materials; multiple Fresnel reflections are much less important for such surfaces.

  16. RTM-based Teleseismic Reflection Tomography with Free Surface Multiples

    Science.gov (United States)

    Burdick, S. A.; De Hoop, M. V.; van der Hilst, R. D.

    2013-12-01

    Receiver function analysis of teleseismic converted and free surface reflected phases has long been a cornerstone of lithospheric studies. Discontinuities in elastic properties are revealed by deconvolving the incident wavefield from scattered phases and projecting the time differences to depth to form an image. The accuracy of the image is determined to a large extent by the accuracy of the method and background velocity model used, but popular approaches for projecting receiver functions to depth commonly rely on simplifying assumptions of a 1D velocity and planar discontinuities. In tectonically complex regions like subduction zones and rift systems, strong heterogeneity can create an ambiguous tradeoff between the background velocity and the depth of the discontinuities. Furthermore, such structures are apt to create caustics at high frequencies, rendering ray-based methods inadequate. In order to better constrain the background velocity and correctly place the discontinuities at depth, we employ a novel reverse-time migration (RTM) based reflection tomography method. We adapt our reflection tomography from exploration seismology for use with teleseismic phases. Active source methods for exploration have focused on the annihilation of extended images - image gathers formed with different subsurface angle or offset information - as a means of judging the accuracy of the model. Applying these approaches to teleseismic data is untenable because 1) the sparse and uneven distribution of earthquake sources leads to the incomplete construction of extended image, 2) the imperfect separation and source deconvolution of the scattered wavefield render previous error measurements unreliable, and 3) the planar geometry of incoming arrivals makes measures of subsurface offset insensitive to perturbations in the model. To overcome these obstacles, we have developed a flexible approach based on pairwise single-source image correlations. We determine the success of the RTM and

  17. Classification and calibration of metal exposure using leaf-level and simulated canopy-level reflectance data

    Science.gov (United States)

    Wilson, Machelle Denise

    Remote sensing technologies with high spatial and spectral resolution show a great deal of promise in addressing critical environmental monitoring issues, but the ability to analyze and interpret the data lags behind the technology. Robust analytical methods are required before the wealth of data available through remote sensing can be applied to a wide range of environmental problems for which remote detection is the best method, e.g. inaccessible areas, sites with potentially hazardous contamination, sites that need routine and frequent monitoring, and where information about the spatial context of such conditions is critical to understanding the location, distribution, or spread of adverse conditions. In this study we compare the effectiveness of several statistical methodologies for the classification and calibration on a data set consisting of leaf-level reflectance from the salt marsh plant Frankenia that has been exposed to varying levels of copper toxicity. We also test these methodologies on simulated canopy-level reflectance produced by feeding the leaf-level data in the SAILH canopy reflectance model. The classification methods compared were support vector classification (SVC) of exposed and non-exposed plants based on the reflectance data, and partial least squares compression of the reflectance data followed by classification using logistic discrimination (PLS/LD). PLS/LD was performed in two ways. We used the continuous concentration data as the response during compression, and then used the binary response required during logistic discrimination. We also used a binary response (-1 for non-exposed, and 1 for exposed) during compression followed by logistic discrimination. The statistic we used to compare the effectiveness of the methodologies was the leave-one-out cross validation estimate of the prediction error. We also calculated the theoretical (probably approximately correct or PAC) bounds on the prediction error of the support vector machine

  18. Mercapto-based coupling agent for improved thermophotovoltaic device back surface reflector adhesion and reflectance

    Energy Technology Data Exchange (ETDEWEB)

    Wernsman, Bernard; Fiedor, Joseph N.; Irr, Lawrence G.; Palmisiano, Marc N.

    2016-10-04

    A back surface reflector (BSR) is described. The BSR includes a reflecting layer, a substrate and an adhesion layer between the reflecting layer and the substrate. The adhesion layer includes 3-mercaptopropyl (trimethoxy) silane (a.k.a. Merc).

  19. Reconstruction of Satellite-Retrieved Land-Surface Reflectance Based on Temporally-Continuous Vegetation Indices

    Directory of Open Access Journals (Sweden)

    Zhiqiang Xiao

    2015-07-01

    Full Text Available Land-surface reflectance, estimated from satellite observations through atmospheric corrections, is an essential parameter for further retrieval of various high level land-surface parameters, such as leaf area index (LAI, fraction of absorbed photosynthetically active radiation (FAPAR, and surface albedo. Although great efforts have been made, land-surface reflectance products still contain considerable noise caused by, e.g., cloud or mixed-cloud pixels, which results in temporal and spatial inconsistencies in subsequent downstream products. In this study, a new method is developed to remove the residual clouds in the Moderate Resolution Imaging Spectroradiometer (MODIS land-surface reflectance product and reconstruct time series of surface reflectance for the red, near infrared (NIR, and shortwave infrared (SWIR bands. A smoothing method is introduced to calculate upper envelopes of vegetation indices (VIs from the surface reflectance data and the cloud contaminated reflectance data are identified using the time series VIs and the upper envelopes of the time series VIs. Surface reflectance was then reconstructed according to cloud-free surface reflectance by incorporating the upper envelopes of the time series VIs as constraint conditions. The method was applied to reconstruct time series of surface reflectance from MODIS/TERRA surface reflectance product (MOD09A1. Temporal consistency analysis indicates that the new method can reconstruct temporally-continuous time series of land-surface reflectance. Comparisons with cloud-free MODIS/AQUA surface reflectance product (MYD09A1 over the BELMANIP (Benchmark Land Multisite Analysis and Intercomparison of Products sites in 2003 demonstrate that the new method provides better performance for the red band (R2 = 0.8606 and RMSE = 0.0366 and NIR band (R2 = 0.6934 and RMSE = 0.0519, than the time series cloud detection (TSCD algorithm (R2 = 0.5811 and RMSE = 0.0649; and R2 = 0.5005 and RMSE = 0

  20. Control and Calibration of a Staubli RX130 Robotic Arm for Construction of Surface Current Coils

    Science.gov (United States)

    Vanmeter, Patrick; Crawford, Christopher; Guler, Emre; Fugal, Mario; Irvin, Bradley

    2013-10-01

    Precision low energy neutron experiments require extremely uniform magnetic fields for manipulating the neutron spin. Such fields can be generated with surface current coils-precision 3-dimensional printed circuits. We are developing a facility to etch out these circuits on copper-plated curved forms using a high-speed spindle attached to the end-effector of a Staubli RX130 six-axis robotic arm. We describe our mathematical model of the robotic links and the software system we designed to control the motion of the arm and to prevent collisions during actuations. We developed a calibration procedure to achieve accuracy of 30 microns in the position of drill.

  1. Surface applicator calibration and commissioning of an electronic brachytherapy system for nonmelanoma skin cancer treatment

    Energy Technology Data Exchange (ETDEWEB)

    Rong, Yi; Welsh, James S. [Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792 and University of Wisconsin Cancer Center-Riverview, Riverview Hospital Association, Wisconsin Rapids, Wisconsin 54494 (United States); Department of Human Oncology and Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792 and University of Wisconsin Cancer Center-Riverview, Riverview Hospital Association, Wisconsin Rapids, Wisconsin 54494 (United States)

    2010-10-15

    Purpose: The Xoft Axxent x-ray source has been used for treating nonmelanoma skin cancer since the surface applicators became clinically available in 2009. The authors report comprehensive calibration procedures for the electronic brachytherapy (eBx) system with the surface applicators. Methods: The Xoft miniature tube (model S700) generates 50 kVp low-energy x rays. The new surface applicators are available in four sizes of 10, 20, 35, and 50 mm in diameter. The authors' tests include measurements of dose rate, air-gap factor, output stability, depth dose verification, beam flatness and symmetry, and treatment planning with patient specific cutout factors. The TG-61 in-air method was used as a guideline for acquiring nominal dose-rate output at the skin surface. A soft x-ray parallel-plate chamber (PTW T34013) and electrometer was used for the output commissioning. GafChromic EBT films were used for testing the properties of the treatment fields with the skin applicators. Solid water slabs were used to verify the depth dose and cutout factors. Patients with basal cell or squamous cell carcinoma were treated with eBx using a calibrated Xoft system with the low-energy x-ray source and the skin applicators. Results: The average nominal dose-rate output at the skin surface for the 35 mm applicator is 1.35 Gy/min with {+-}5% variation for 16 sources. The dose-rate output and stability (within {+-}5% variation) were also measured for the remaining three applicators. For the same source, the output variation is within 2%. The effective source-surface distance was calculated based on the air-gap measurements for four applicator sizes. The field flatness and symmetry are well within 5%. Percentage depth dose in water was provided by factory measurements and can be verified using solid water slabs. Treatment duration was calculated based on the nominal dose rate, the prescription fraction size, the depth dose percentage, and the cutout factor. The output factor needs

  2. Evaluation of the homogeneity of reference flat sources used in calibration of surface contamination monitors

    International Nuclear Information System (INIS)

    Silva Junior, I.A.; Xavier, M.; Siqueira, P.T.D.; Potiens, M.P.A.

    2014-01-01

    The aim of this study was to re-evaluate the uniformity of the wide area reference sources of the Calibration Laboratory of Instruments (LCI-IPEN) used in the calibration of surface contamination monitors, according the recommendations of the ISO 8769 standard and the NRPB. In this work used six wide area reference sources of 150 cm 2 of 241 Am, 14 C, 36 Cl, 137 Cs, 90 Sr+ 90 Y and 99 Tc with reference dates between 1996 and 1997 and three sources of 100 cm 2 of 14 C, 137 Cs and 60 Co were used with reference dates 2007. Measurements were performed with a radiation monitor of the Thermo, model FH40GX with a pancake probe, model FHZ732GM. We also made several models on paper with the objective of define each measurement position and an aluminum plate with a square hole (6.25 cm 2 ) in its center, allowing the passage of the radiation only through the hole. Each wide area reference source was positioned in setup and measurements were performed in order to cover the entire surface of the source. The values of the uniformity obtained partially confirm previous data obtained in another study conducted by LCI-IPEN, showing that some wide area reference sources 150 cm 2 in disagree with ISO 8769. In the former work, just the source of 241 Am (7.3%) was within the range specified by the standard, now have sources of 241 Am (5.7%), 137 Cs (8.8%), 90 Sr+ 9 '0Y (8, 8%) and 99 Tc (9.2%) with values within the specified uniformity. The sources of 14 C (53.3%) and 36 Cl (16.6%) were outside the specified. The wide area reference sources of 100 cm 2 , show disagreement in values of uniformity of the sources 14 C (46.7%) and 60 Co (10.4%). The values of the uniformity of the wide area reference sources show that some fonts can not be used in calibrations, because not in accordance with the value of uniformity specified in ISO 8769:2010, this is a conditions to believe a laboratory according to ISO 17025, show the laboratory performs its services with a high quality. The

  3. Comparison of ultraviolet Bi-directional Reflectance Distribution Function (BRDF) measurements of diffusers used in the calibration of the Total Ozone Mapping Spectrometer (TOMS)

    NARCIS (Netherlands)

    Butler, J.J.; Park, H.; Barnes, P.Y.; Early, E.A.; Eijk-Olij, C. van; Zoutman, A.E.; Buller-Leeuwen, S. van; Groote Schaarsberg, J.

    2002-01-01

    The measurement and long-term monitoring of global total ozone by ultraviolet albedo measuring satellite instruments require accurate and precise determination of the Bi-directional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in the pre-launch calibration of those

  4. Sensitivity analysis and development of calibration methodology for near-surface hydrogeology model of Forsmark

    International Nuclear Information System (INIS)

    Aneljung, Maria; Gustafsson, Lars-Goeran

    2007-04-01

    The hydrological modelling system MIKE SHE has been used to describe near-surface groundwater flow, transport mechanisms and the contact between ground- and surface water at the Forsmark site. The surface water system at Forsmark is described with the 1D modelling tool MIKE 11, which is fully and dynamically integrated with MIKE SHE. In spring 2007, a new data freeze will be available and a process of updating, rebuilding and calibrating the MIKE SHE model will start, based on the latest data set. Prior to this, it is important to gather as much knowledge as possible on calibration methods and to define critical calibration parameters and areas within the model. In this project, an optimization of the numerical description and an initial calibration of the MIKE SHE model has been made, and an updated base case has been defined. Data from 5 surface water level monitoring stations, 4 surface water discharge monitoring stations and 32 groundwater level monitoring stations (SFM soil boreholes) has been used for model calibration and evaluation. The base case simulations generally show a good agreement between calculated and measured water levels and discharges, indicating that the total runoff from the area is well described by the model. Moreover, with two exceptions (SFM0012 and SFM0022) the base case results show very good agreement between calculated and measured groundwater head elevations for boreholes installed below lakes. The model also shows a reasonably good agreement between calculated and measured groundwater head elevations or depths to phreatic surfaces in many other points. The following major types of calculation-measurement differences can be noted: Differences in groundwater level amplitudes due to transpiration processes. Differences in absolute mean groundwater head, due to differences between borehole casing levels and the interpolated DEM. Differences in absolute mean head elevations, due to local errors in hydraulic conductivity values

  5. A non-invasive diffuse reflectance calibration-free method for absolute determination of exogenous biochemicals concentration in biological tissues

    Science.gov (United States)

    Lappa, Alexander V.; Kulikovskiy, Artem N.; Busarov, Oleg G.

    2014-03-01

    The paper presents a new method for distant non-destructive determination of concentration of light absorbing admixtures in turbid media. In particular, it is intended for non-invasive in vivo control of accumulation in patient tissues of various biochemicals introduced to the patients for chemotherapy, photodynamic therapy or diagnostics. It is require that the admixture absorption spectrum should have a clearly marked peak in the wavelength region where the pure medium one varies regularly. Fluorescence of admixtures is not required. The method uses the local diffuse reflectance spectroscopy with optical fiber probe including one emitting and two reading There are several features in the method: the value to be determined is absolute concentration of admixtures; the method needs no calibration measurements on phantoms; it needs no reference measurements on sample with zero admixture concentration; it uses a two parametric kinetic light propagation model and original algorithms to resolve direct and inverse tasks of radiation transport theory. Experimental testing passed with tissue equivalent phantoms and different admixtures, including a chlorine photosensitizer, showed accuracy under 10% in all cases.

  6. Calibration of the scales of areal surface topography measuring instruments: part 3. Resolution

    International Nuclear Information System (INIS)

    Giusca, Claudiu L; Leach, Richard K

    2013-01-01

    Calibration of the scales of areal surface topography measuring instruments requires testing of the resolution. Several designs of artefact that allow testing of the resolution of such instruments are currently available; however, analysis methods need to be developed to provide comparable results. A novel method for determining the lateral resolution of areal surface topography measuring instruments is presented. The method uses a type ASP (star-shaped) material measure. To demonstrate the validity of the method, the resolution of a phase shifting interferometer was determined based on the ISO definition of the lateral period limit. Using the proposed method, the type ASP material measure, which is often used to judge qualitatively an instrument's resolution, can be used to quantitatively estimate the resolution of instruments using the topography data. (paper)

  7. Overcoming the reference large-area sources non-uniformity in surface area monitor calibration

    Energy Technology Data Exchange (ETDEWEB)

    Junior, Iremar Alves S.; Siqueira, Paulo de T.D.; Xavier, Marcs; Nascimento, Eduardo do; Potiens, Maria da Penha A., E-mail: iremarjr@usp.br, E-mail: ptsiquei@ipen.br, E-mail: mxavier@ipen.br, E-mail: eduardon@ufba.br, E-mail: mppalbu@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    This paper describes a study using MCNP5 simulations, a Monte Carlo based radiation transport code, in order to evaluate the possibility of using reference large-area sources that do not meet the uniformity recommendations of the ISO 8769:2010 in surface contamination monitors calibration. {sup 14}C, {sup 36}Cl, {sup 99}Tc, {sup 137}Cs and {sup 90}Sr + {sup 90}Y large area reference sources were simulated as well as the setup and the detector probe. Simulations were carried out for both uniform and non-uniform surface distributions. In the case of uniform distribution, specific weights for each region were considered, as obtained in the uniformity evaluation measurements. To each simulation, it was considered the average number of signals generated in each detector probe, i.e., it was determined the fraction of stories depositing energy in the corresponding gas filled region of the detector. Simulations results show differences in detection efficiency values up to 15%. (author)

  8. VIIRS/NPP Surface Reflectance 8-Day L3 Global 500m SIN Grid V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The 8-day Visible Infrared Imaging Radiometer Suite (VIIRS) Surface Reflectance (VNP09H1) Version 1 composite product provides an estimate of land surface...

  9. Binary Pseudo-Random Gratings and Arrays for Calibration of Modulation Transfer Functions of Surface Profilometers

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Samuel K.; Anderson, Erik D.; Cambie, Rossana; McKinney, Wayne R.; Takacs, Peter Z.; Stover, John C.; Voronov, Dmitriy L.; Yashchuk, Valeriy V.

    2009-09-11

    A technique for precise measurement of the modulation transfer function (MTF), suitable for characterization of a broad class of surface profilometers, is investigated in detail. The technique suggested in [Proc. SPIE 7077-7, (2007), Opt. Eng. 47(7), 073602-1-5 (2008)]is based on use of binary pseudo-random (BPR) gratings and arrays as standard MTF test surfaces. Unlike most conventional test surfaces, BPR gratings and arrays possess white-noise-like inherent power spectral densities (PSD), allowing the direct determination of the one- and two-dimensional MTF, respectively, with a sensitivity uniform over the entire spatial frequency range of a profiler. In the cited work, a one dimensional realization of the suggested method based on use of BPR gratings has been demonstrated. Here, a high-confidence of the MTF calibration technique is demonstrated via cross comparison measurements of a number of two dimensional BPR arrays using two different interferometric microscopes and a scatterometer. We also present the results of application of the experimentally determined MTF correction to the measurement taken with the MicromapTM-570 interferometric microscope of the surface roughness of a super-polished test mirror. In this particular case, without accounting for the instrumental MTF, the surface rms roughness over half of the instrumental spatial frequency bandwidth would be underestimated by a factor of approximately 1.4.

  10. Light Reflection from Water Surfaces Perturbed by Falling Rain Droplets

    Science.gov (United States)

    Molesini, Giuseppe; Vannoni, Maurizio

    2009-01-01

    An account of peculiar light patterns produced by reflection in a pool under falling rain droplets was recently reported by Molesini and Vannoni (2008 Eur. J. Phys. 29 403-11). The mathematical approach, however, only covered the case of a symmetrical location of a light source and the observer's eyes with respect to the vertical of the falling…

  11. An instrument for the measurement of road surface reflection properties

    DEFF Research Database (Denmark)

    Corell, Dennis Dan; Sørensen, K.

    2017-01-01

    surfaces in use have changed - for instance to road surface types with less noise from wheel passages. Because of this, a co-operation between the road administrations of the Nordic countries (abbreviated NMF) decided to construct a portable instrument to be used on selections of traffic roads within...

  12. Orientation effect of ion flux splitting reflected from Wehner cone on solid surface

    CERN Document Server

    Bratchenko, M I; Rozhkov, V V

    2001-01-01

    It is shown that simple geometrical model of specular reflection of particles from the surface of Wehner cone (frequently observed feature of solid surface macroscopic topography developed under ion bombardment) can describe qualitatively the essential characteristics of the reflected particles flux splitting effect predicted earlier by means of computer simulation methods.

  13. A Monte Carlo reflectance model for soil surfaces with three-dimensional structure

    Science.gov (United States)

    Cooper, K. D.; Smith, J. A.

    1985-01-01

    A Monte Carlo soil reflectance model has been developed to study the effect of macroscopic surface irregularities larger than the wavelength of incident flux. The model treats incoherent multiple scattering from Lambertian facets distributed on a periodic surface. Resulting bidirectional reflectance distribution functions are non-Lambertian and compare well with experimental trends reported in the literature. Examples showing the coupling of the Monte Carlo soil model to an adding bidirectional canopy of reflectance model are also given.

  14. Land surface model performance using cosmic-ray and point-scale soil moisture measurements for calibration

    Directory of Open Access Journals (Sweden)

    J. Iwema

    2017-06-01

    Full Text Available At very high resolution scale (i.e. grid cells of 1 km2, land surface model parameters can be calibrated with eddy-covariance flux data and point-scale soil moisture data. However, measurement scales of eddy-covariance and point-scale data differ substantially. In our study, we investigated the impact of reducing the scale mismatch between surface energy flux and soil moisture observations by replacing point-scale soil moisture data with observations derived from Cosmic-Ray Neutron Sensors (CRNSs made at larger spatial scales. Five soil and evapotranspiration parameters of the Joint UK Land Environment Simulator (JULES were calibrated against point-scale and Cosmic-Ray Neutron Sensor soil moisture data separately. We calibrated the model for 12 sites in the USA representing a range of climatic, soil, and vegetation conditions. The improvement in latent heat flux estimation for the two calibration solutions was assessed by comparison to eddy-covariance flux data and to JULES simulations with default parameter values. Calibrations against the two soil moisture products alone did show an advantage for the cosmic-ray technique. However, further analyses of two-objective calibrations with soil moisture and latent heat flux showed no substantial differences between both calibration strategies. This was mainly caused by the limited effect of calibrating soil parameters on soil moisture dynamics and surface energy fluxes. Other factors that played a role were limited spatial variability in surface fluxes implied by soil moisture spatio-temporal stability, and data quality issues.

  15. Liquid Atomization Induced by Pulse Laser Reflection underneath Liquid Surface

    Science.gov (United States)

    Utsunomiya, Yuji; Kajiwara, Takashi; Nishiyama, Takashi; Nagayama, Kunihito; Kubota, Shiro; Nakahara, Motonao

    2009-05-01

    We observed a novel effect of pulse laser reflection at the interface between transparent materials with different refractive indices. The electric field intensity doubles when a laser beam is completely reflected from a material with a higher refractive index to a material with a lower index. This effect appreciably reduces pulse laser ablation threshold of transparent materials. We performed experiments to observe the entire ablation process for laser incidence on the water-air interface using pulse laser shadowgraphy with high-resolution film; the minimum laser fluence for laser ablation at the water-air interface was approximately 12-16 J/cm2. We confirmed that this laser ablation occurs only when the laser beam is incident on the water-air interface from water. Many slender liquid ligaments extend like a milk crown and seem to be atomized at the tip. Their detailed structures can be resolved only by pulse laser photography using high-resolution film.

  16. Reflectivity reduction of retro-reflector installed in LHD due to plasma surface interaction

    International Nuclear Information System (INIS)

    Yoshida, N.; Ohtawa, Y.; Ebihara, A.; Akiyama, T.; Tokitani, M.; Ashikawa, N.; Kawahata, K.

    2008-10-01

    Optical reflectivity of the retro-reflector installed in LHD as the first mirror was reduced seriously by plasma wall interaction. In order to understand the mechanism of the reflectivity reduction, optical and material properties of the mirror surfaces have been examined extensively. It was found that the deposited impurity layers caused the serious reduction of the reflectivity. Formation of iron oxide, bulges structure and He bubbles are the major factors for the reflectivity reduction in the wide wave length range. (author)

  17. Sr/Ca-Sea surface temperature calibration in the branching Caribbean coral Acropora palmata

    Science.gov (United States)

    Gallup, Christina D.; Olson, Donna M.; Edwards, R. Lawrence; Gruhn, Leah M.; Winter, Amos; Taylor, Frederick W.

    2006-02-01

    We measured Sr/Ca ratios by thermal ionization mass spectrometry in radial and axial growth of modern Caribbean Acropora palmata corals. Comparison of our results with sea surface temperature (SST) allows radial and axial Sr/Ca-SST calibrations of Sr/Ca (mmol/mol) = 11.30 - 0.07072 × SST (°C) and Sr/Ca (mmol/mol) = 11.32 - 0.06281 x SST (°C), respectively. Application of the calibrations to fossil Acropora palmata from the last glacial maximum in Barbados (Guilderson et al., 1994) imply ~7°C cooler conditions than the present, much larger than the 1-1.5° cooling suggested by modern analog technique foraminifera-based estimates (Trend-Staid and Prell, 2002). If the foraminifera-based estimates are correct, then the excess cooling suggested by the Barbados corals could be explained by a 5% shift in the marine Sr/Ca ratio or an addition of ~20% abiotic secondary aragonite.

  18. Self Calibration of a 2-wavelength Pyrometer

    Science.gov (United States)

    Ng, Daniel

    1998-01-01

    Pyrometers require calibrations to determine their instrument constants before they can be used in remote temperature measurements. These constants reflect the combined effects of detector response, the transmissivities of intervening optical media (windows and gases) and the emissivity of the measured surface. We describe here the principal and the demonstration of self calibrating 2-wavelength pyrometer.

  19. Removal of Surface-Reflected Light for the Measurement of Remote-Sensing Reflectance from an Above-Surface Platform

    Science.gov (United States)

    2010-12-06

    REPORT DATE IDD-MM- YYYY) 14-02-2011 2. REPORT TYPE Journal Article 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Removal of Surface...impossible to obtain Rr, from measurements of vertical profiles of Lu and Elt [6]. During the experiment, the surface was calm [see Fig. 8(a)] and

  20. Free hand proprioception is well calibrated to verbal estimates of slanted surfaces.

    Science.gov (United States)

    Shaffer, Dennis M; Taylor, Ally

    2017-02-01

    We investigate the relationship between verbal and hand proprioception of slant. In Experiment 1 we demonstrate that verbally estimating free hand orientation produces overestimates by a factor of 1.67. These values are similar to those seen for verbal overestimates of slanted surfaces. In Experiment 2, participants positioned their hand to a ramp at 1 of 4 different orientations, and then verbally estimated the orientation of either their hand or the ramp. We show that verbal estimates of the ramp are a product of the orientation of their hand and the perception of the orientation of their hand. We discuss how this work is consistent with the proprioception calibration hypothesis that proposes that similar biases exist in both verbal estimates of visually perceived slant and proprioceptively perceived hand orientation and how this may explain free hand estimates to outdoor hills that are greater than actual hill orientation by a factor of ~2, but are still less than verbal (over)estimates.

  1. Calibration and validation of a small-scale urban surface water flood event using crowdsourced images

    Science.gov (United States)

    Green, Daniel; Yu, Dapeng; Pattison, Ian

    2017-04-01

    Surface water flooding occurs when intense precipitation events overwhelm the drainage capacity of an area and excess overland flow is unable to infiltrate into the ground or drain via natural or artificial drainage channels, such as river channels, manholes or SuDS. In the UK, over 3 million properties are at risk from surface water flooding alone, accounting for approximately one third of the UK's flood risk. The risk of surface water flooding is projected to increase due to several factors, including population increases, land-use alterations and future climatic changes in precipitation resulting in an increased magnitude and frequency of intense precipitation events. Numerical inundation modelling is a well-established method of investigating surface water flood risk, allowing the researcher to gain a detailed understanding of the depth, velocity, discharge and extent of actual or hypothetical flood scenarios over a wide range of spatial scales. However, numerical models require calibration of key hydrological and hydraulic parameters (e.g. infiltration, evapotranspiration, drainage rate, roughness) to ensure model outputs adequately represent the flood event being studied. Furthermore, validation data such as crowdsourced images or spatially-referenced flood depth collected during a flood event may provide a useful validation of inundation depth and extent for actual flood events. In this study, a simplified two-dimensional inertial based flood inundation model requiring minimal pre-processing of data (FloodMap-HydroInundation) was used to model a short-duration, intense rainfall event (27.8 mm in 15 minutes) that occurred over the Loughborough University campus on the 28th June 2012. High resolution (1m horizontal, +/- 15cm vertical) DEM data, rasterised Ordnance Survey topographic structures data and precipitation data recorded at the University weather station were used to conduct numerical modelling over the small (present during the flood event via the

  2. Preparation of surface conductive and highly reflective silvered polyimide films by surface modification and in situ self-metallization technique

    International Nuclear Information System (INIS)

    Wu Zhanpeng; Wu Dezhen; Qi Shengli; Zhang Teng; Jin Riguang

    2005-01-01

    Double surface conductive and reflective flexible silvered polyimide films have been prepared by alkali hydroxylation of polyimide film surface and incorporation of silver ions through subsequent ion exchange. Thermal curing of silver(I) polyamate precursor leads to re-cycloimidization of modified surface with concomitant silver reduction, yielding a reflective and conductive silver surface approaching that of native metal. The reflective and conductive surface evolves only when the cure temperature rises to 300 deg. C. The metallized films usually retain the essential mechanical properties of the parent films. Films were characterized by transmission electron microscopy (TEM), scanning electron microscopy and tapping mode atomic force microscopy (AFM). AFM demonstrates that the diameter of close-packed silver particles of the silver layers was about 50-150 nm. TEM shows that thickness of silver layer on the polyimide film surface is about 400-600 nm

  3. High quality broadband spatial reflections of slow Rayleigh surface acoustic waves modulated by a graded grooved surface

    KAUST Repository

    Xu, Yanlong

    2015-01-21

    We report high quality broadband spatial reflections of Rayleigh surface acoustic waves (SAWs) through a graded grooved surface. High quality means that no wave is allowed to transmit and the incident wave is nearly all reflected to the input side. The graded grooved surface is structured by drilling one dimensional array of graded grooves with increased depths on a flat surface. We investigate SAW dispersion relations, wave field distribution at several typical SAW wavelengths, and time evolution of a Gaussian pulse through the graded grooved surface. Results show that the input broadband Rayleigh SAWs can be slowed, spatially enhanced and stopped, and finally reflected to the input side. The study suggests that engraving the flat surface can be used as an efficient and economical way to manipulate Rayleigh SAWs, which has potential application in novel SAW devices such as filters, reflectors, sensors, energy harvesters, and diodes.

  4. Spectral reflectance of surface soils: Relationships with some soil properties

    Science.gov (United States)

    Kiesewetter, C. H.

    1983-01-01

    Using a published atlas of reflectance curves and physicochemical properties of soils, a statistical analysis was carried out. Reflectance bands which correspond to five of the wavebands used by NASA's Thematic Mapper were examined for relationships to specific soil properties. The properties considered in this study include: Sand Content, Silt Content, Clay Content, Organic Matter Content, Cation Exchange Capacity, Iron Oxide Content and Moisture Content. Regression of these seven properties on the mean values of five TM bands produced results that indicate that the predictability of the properties can be increased by stratifying the data. The data was stratified by parent material, taxonomic order, temperature zone, moisture zone and climate (combined temperature and moisture). The best results were obtained when the sample was examined by climatic classes. The middle Infra-red bands, 5 and 7, as well as the visible bands, 2 and 3, are significant in the model. The near Infra-red band, band 4, is almost as useful and should be included in any studies. General linear modeling procedures examined relationships of the seven properties with certain wavebands in the stratified samples.

  5. Estimating aerodynamic resistance of rough surfaces from angular reflectance

    Science.gov (United States)

    Current wind erosion and dust emission models neglect the heterogeneous nature of surface roughness and its geometric anisotropic effect on aerodynamic resistance, and over-estimate the erodible area by assuming it is not covered by roughness elements. We address these shortfalls with a new model wh...

  6. Vicarious calibration of the solar reflection channels of radiometers onboard satellites through the field campaigns with measurements of refractive index and size distribution of aerosols

    Science.gov (United States)

    Arai, K.

    A comparative study on vicarious calibration for the solar reflection channels of radiometers onboard satellite through the field campaigns between with and without measurements of refractive index and size distribution of aerosols is made. In particular, it is noticed that the influence due to soot from the cars exhaust has to be care about for the test sites near by a heavy trafficked roads. It is found that the 0.1% inclusion of soot induces around 10% vicarious calibration error so that it is better to measure refractive index properly at the test site. It is found that the vicarious calibration coefficients with the field campaigns at the different test site, Ivanpah (near road) and Railroad (distant from road) shows approximately 10% discrepancy. It seems that one of the possible causes for the difference is the influence due to soot from cars exhaust.

  7. Angular calibration of surface slope measuring profilers with a bendable mirror

    Science.gov (United States)

    Artemiev, Nikolay A.; Smith, Brian V.; Domning, Edward E.; Chow, Ken P.; Lacey, Ian; Yashchuk, Valeriy V.

    2014-09-01

    Performance of state-of-the-art surface slope measuring profilers, such as the Advanced Light Source's (ALS) long trace profiler (LTP-II) and developmental LTP (DLTP) is limited by the instrument's systematic error. The systematic error is specific for a particular measurement arrangement and, in general, depends on both the measured surface slope value and the position along a surface under test. Here we present an original method to characterize or measure the instrument's systematic error using a bendable X-ray mirror as a test surface. The idea of the method consists of extracting the systematic error from multiple measurements performed at different mirror bendings. An optimal measurement strategy for the optic, under different settings of the benders, and the method of accurate fitting of the measured slope variations with characteristic functions are discussed. We describe the procedure of separation of the systematic error of an actual profiler from surface slope variation inherent to the optic. The obtained systematic error, expressed as a function of the angle of measurement, is useful as a calibration of the instrument arranged to measure an optic with a close curvature and length. We show that accounting for the systematic error enables the optimal setting of bendable optics to the desired ideal shape with accuracy limited only by the experimental noise. Application of the method in the everyday metrology practice increases the accuracy of the measurements and allows measurements of highly curved optics with accuracy similar to those achieved with flat optics. This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  8. STACKING ON COMMON REFLECTION SURFACE WITH MULTIPARAMETER TRAVELTIME

    Directory of Open Access Journals (Sweden)

    Montes V. Luis A.

    2006-12-01

    Full Text Available Commonly seismic images are displayed in time domain because the model in depth can be known only in well logs. To produce seismic sections, pre and post stack processing approaches use time or depth velocity models whereas the common reflection method does not, instead it requires a set of parameters established for the first layer. A set of synthetic data of an anticline model, with sources and receivers placed on a flat topography, was used to observe the performance of this method. As result, a better reflector recovering compared against conventional processing sequence was observed.
    The procedure was extended to real data, using a dataset acquired on a zone characterized by mild topography and quiet environment reflectors in the Eastern Colombia planes, observing an enhanced and a better continuity of the reflectors in the CRS stacked section.

  9. Surface Bubbles in the Bathtub and Reflections on Ripple Tanks

    Science.gov (United States)

    Greenslade, Thomas B.

    2012-01-01

    Bathtubs are splendid places for studying physics! Recently I was happily splashing about and noticed that the light from the lamp above me was being focused as bright spots on the bottom of the tub. Closer inspection showed that the spots were surrounded by dark rings. This pattern turned out to be due to the lensing effect of bubbles floating on the surface of the water.

  10. Unmanned aerial system nadir reflectance and MODIS nadir BRDF-adjusted surface reflectances intercompared over Greenland

    Directory of Open Access Journals (Sweden)

    J. F. Burkhart

    2017-07-01

    Full Text Available Albedo is a fundamental parameter in earth sciences, and many analyses utilize the Moderate Resolution Imaging Spectroradiometer (MODIS bidirectional reflectance distribution function (BRDF/albedo (MCD43 algorithms. While derivative albedo products have been evaluated over Greenland, we present a novel, direct comparison with nadir surface reflectance collected from an unmanned aerial system (UAS. The UAS was flown from Summit, Greenland, on 210 km transects coincident with the MODIS sensor overpass on board the Aqua and Terra satellites on 5 and 6 August 2010. Clear-sky acquisitions were available from the overpasses within 2 h of the UAS flights. The UAS was equipped with upward- and downward-looking spectrometers (300–920 nm with a spectral resolution of 10 nm, allowing for direct integration into the MODIS bands 1, 3, and 4. The data provide a unique opportunity to directly compare UAS nadir reflectance with the MODIS nadir BRDF-adjusted surface reflectance (NBAR products. The data show UAS measurements are slightly higher than the MODIS NBARs for all bands but agree within their stated uncertainties. Differences in variability are observed as expected due to different footprints of the platforms. The UAS data demonstrate potentially large sub-pixel variability of MODIS reflectance products and the potential to explore this variability using the UAS as a platform. It is also found that, even at the low elevations flown typically by a UAS, reflectance measurements may be influenced by haze if present at and/or below the flight altitude of the UAS. This impact could explain some differences between data from the two platforms and should be considered in any use of airborne platforms.

  11. Evaluation of depth of surface-breaking slit by nondestructive self-calibrating technique using laser based ultrasound

    International Nuclear Information System (INIS)

    Lee, Joon Hyun; Choi, Sang Woo; Ha, Sang Bong

    2002-01-01

    It is required to evaluate nondestructively the crack depth of surface-breaking cracks for the assurance of safety of structure. Optical generation of ultrasound produces well defined pulses with a repeatable frequency content, that are free of any mechanical resonances; they are broad band and are ideal for the measurement of attenuation and scattering over a wide frequency range. Self-calibrating surface signal transmission measurement is very sensitive and practical tool for surface-breaking crack depth. In his paper, the self-calibrating technique by laser-based ultrasound is used to evaluate the depth of surface-breaking crack of material. It is suggested that the relationship between the signal transmission and crack depth can be used as a practical model for predicting the surface-breaking crack depths from the signal transmission measured in structure

  12. The TMS-1 corneal topography measurement applied to calibrated ellipsoidal convex surfaces.

    Science.gov (United States)

    Douthwaite, W A; Matilla, M T

    1996-03-01

    The purpose of this report is to assess the accuracy of the TMS-1 videokeratoscope (Computed Anatomy Inc.) by using convex ellipsoidal surfaces. The ellipsoids were calibrated using Form Talysurf analysis, which allowed for subsequent calculation of the vertex radius and p value. The videokeratoscope was used to examine the same ellipsoids. The data provided by the instrument software were used to plot a graph of r2 verses y2, where r is the measured radius at y, the distance from the corneal point being measured to the optical axis of the instrument. The intercept on the ordinate of this graph gives the vertex radius, and the slope give the p value. The results arising from the Talysurf and the TMS-1 techniques were compared. The TMS-1 videokeratoscope gave readings for the vertex radius that were generally higher than those of the Talysurf analysis. The vertex radius was up to 0.09 mm greater. The p value results were similar by the two methods for p values of approximately 0.8; however, the TMS-1 results were higher, and the discrepancy increased as the p value approached that of a paraboloid. Although the videokeratoscope may be useful in comparative studies of the cornea, there must be some doubt about the absolute values displayed as the surface becomes increasingly aspheric.

  13. LBA-ECO CD-34 Hyperion 30-m Surface Reflectance, Amazon Basin: 2002-2005

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains 20 multispectral surface reflectance images collected by the EO-1 satellite Hyperion sensor at 30-m resolution and covering the entire Amazon...

  14. MODIS/Terra Surface Reflectance Daily L2G Global 250m SIN Grid V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MOD09GQ Version 6 product provides an estimate of the surface spectral reflectance of Terra MODIS 250 m bands 1-2 corrected for atmospheric conditions such as...

  15. LiDAR Relative Reflectivity Surface (2011) for the St. Thomas East End Reserve, St. Thomas

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a LiDAR (Light Detection & Ranging) 0.3x0.3 meter resolution relative seafloor reflectivity surface for the St. Thomas East End Reserve...

  16. CLPX-Satellite: EO-1 Hyperion Surface Reflectance, Snow-Covered Area, and Grain Size

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of apparent surface reflectance, subpixel snow-covered area and grain size collected from the Hyperion hyperspectral imager. The Hyperion...

  17. NOAA Climate Data Record (CDR) of AVHRR Surface Reflectance, Version 4

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains gridded daily surface reflectance and brightness temperatures derived from the Advanced Very High Resolution Radiometer (AVHRR) sensors onboard...

  18. ASTER L2 Surface Reflectance VNIR and Crosstalk Corrected SWIR V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The ASTER L2 Surface Reflectance is a multi-file product that contains atmospherically corrected data for both the Visible Near-Infrared (VNIR) and Shortwave...

  19. MODIS/Aqua Surface Reflectance 8-Day L3 Global 250m SIN Grid V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MYD09Q1 Version 6 product provides an estimate of the surface spectral reflectance of AQUA MODIS Bands 1-2 corrected for atmospheric conditions such as gasses,...

  20. MODIS/Aqua Surface Reflectance Daily L3 Global 0.05Deg CMG V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MYD09CMG Version 6 product provides an estimate of the surface spectral reflectance of AQUA MODIS Bands 1-7 resampled to 5600 m pixel resolution and corrected...

  1. VIIRS/NPP Surface Reflectance Daily L3 Global 0.05 Deg CMG V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The Visible Infrared Imaging Radiometer Suite (VIIRS) daily surface reflectance Climate Modeling Grid (VNP09CMG) Version 1 product provides an estimate of land...

  2. MODIS/Aqua Surface Reflectance 8-Day L3 Global 500m SIN Grid V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MYD09A1 Version 6 product provides an estimate of the surface spectral reflectance of AQUA MODIS Bands 1-7 corrected for atmospheric conditions such as gasses,...

  3. Simulation and Measurement of Angle Resolved Reflectance from Black Si Surfaces

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Wu, Kaiyu; Schmidt, Michael Stenbæk

    2015-01-01

    In this work angle-resolved reflectance from nanostructured Si surfaces realized by maskless RIE texturing has been simulated and measured. The simulation and experimental measurement data show the same trend. Experimentally a total reflectance below 1% for incident angles below 30o and specular...

  4. Backscattered EM-wave manipulation using low cost 1-bit reflective surface at W-band

    Science.gov (United States)

    Taher Al-Nuaimi, Mustafa K.; Hong, Wei; He, Yejun

    2018-04-01

    The design of low cost 1-bit reflective (non-absorptive) surfaces for manipulation of backscattered EM-waves and radar cross section (RCS) reduction at W-band is presented in this article. The presented surface is designed based on the reflection phase cancellation principle. The unit cell used to compose the proposed surface has an obelus (division symbol of short wire and two disks above and below) like shape printed on a grounded dielectric material. Using this unit cell, surfaces that can efficiently manipulate the backscattered RCS pattern by using the proposed obelus-shaped unit cell (as ‘0’ element) and its mirrored unit cell (as ‘1’ element) in one surface with a 180°  ±  35° reflection phase difference between their reflection phases are designed. The proposed surfaces can generate various kinds of backscattered RCS patterns, such as single, three, or four lobes or even a low-level (reduced RCS) diffused reflection pattern when those two unit cells are distributed randomly across the surface aperture. For experimental characterization purposes, a 50  ×  50 mm2 surface is fabricated and measured.

  5. Vicarious Calibration of sUAS Microbolometer Temperature Imagery for Estimation of Radiometric Land Surface Temperature

    Directory of Open Access Journals (Sweden)

    Alfonso Torres-Rua

    2017-06-01

    Full Text Available In recent years, the availability of lightweight microbolometer thermal cameras compatible with small unmanned aerial systems (sUAS has allowed their use in diverse scientific and management activities that require sub-meter pixel resolution. Nevertheless, as with sensors already used in temperature remote sensing (e.g., Landsat satellites, a radiance atmospheric correction is necessary to estimate land surface temperature. This is because atmospheric conditions at any sUAS flight elevation will have an adverse impact on the image accuracy, derived calculations, and study replicability using the microbolometer technology. This study presents a vicarious calibration methodology (sUAS-specific, time-specific, flight-specific, and sensor-specific for sUAS temperature imagery traceable back to NIST-standards and current atmospheric correction methods. For this methodology, a three-year data collection campaign with a sUAS called “AggieAir”, developed at Utah State University, was performed for vineyards near Lodi, California, for flights conducted at different times (early morning, Landsat overpass, and mid-afternoon” and seasonal conditions. From the results of this study, it was found that, despite the spectral response of microbolometer cameras (7.0 to 14.0 μm, it was possible to account for the effects of atmospheric and sUAS operational conditions, regardless of time and weather, to acquire accurate surface temperature data. In addition, it was found that the main atmospheric correction parameters (transmissivity and atmospheric radiance significantly varied over the course of a day. These parameters fluctuated the most in early morning and partially stabilized in Landsat overpass and in mid-afternoon times. In terms of accuracy, estimated atmospheric correction parameters presented adequate statistics (confidence bounds under ±0.1 for transmissivity and ±1.2 W/m2/sr/um for atmospheric radiance, with a range of RMSE below 1.0 W/m2/sr

  6. Replication and dimensional quality control of industrial nanoscale surfaces using calibrated AFM measurements and SEM image processing

    DEFF Research Database (Denmark)

    Tosello, Guido; Hansen, Hans Nørgaard; Marinello, F.

    2010-01-01

    application of AFM to calibrate height, depth and pitch of sub-micrometer features and SEM image processing to detect replication accuracy in terms of number of replicated features. Surface replication is analyzed using a metrological approach: nano-features on nickel stampers and injection...

  7. Retrieval and Validation of aerosol optical properties from AHI measurements: impact of surface reflectance assumption

    Science.gov (United States)

    Lim, H.; Choi, M.; Kim, J.; Go, S.; Chan, P.; Kasai, Y.

    2017-12-01

    This study attempts to retrieve the aerosol optical properties (AOPs) based on the spectral matching method, with using three visible and one near infrared channels (470, 510, 640, 860nm). This method requires the preparation of look-up table (LUT) approach based on the radiative transfer modeling. Cloud detection is one of the most important processes for guaranteed quality of AOPs. Since the AHI has several infrared channels, which are very advantageous for cloud detection, clouds can be removed by using brightness temperature difference (BTD) and spatial variability test. The Yonsei Aerosol Retrieval (YAER) algorithm is basically utilized on a dark surface, therefore a bright surface (e.g., desert, snow) should be removed first. Then we consider the characteristics of the reflectance of land and ocean surface using three visible channels. The known surface reflectivity problem in high latitude area can be solved in this algorithm by selecting appropriate channels through improving tests. On the other hand, we retrieved the AOPs by obtaining the visible surface reflectance using NIR to normalized difference vegetation index short wave infrared (NDVIswir) relationship. ESR tends to underestimate urban and cropland area, we improved the visible surface reflectance considering urban effect. In this version, ocean surface reflectance is using the new cox and munk method which considers ocean bidirectional reflectance distribution function (BRDF). Input of this method has wind speed, chlorophyll, salinity and so on. Based on validation results with the sun-photometer measurement in AErosol Robotic NETwork (AERONET), we confirm that the quality of Aerosol Optical Depth (AOD) from the YAER algorithm is comparable to the product from the Japan Aerospace Exploration Agency (JAXA) retrieval algorithm. Our future update includes a consideration of improvement land surface reflectance by hybrid approach, and non-spherical aerosols. This will improve the quality of YAER

  8. Total internal reflection fluorescence anisotropy imaging microscopy: setup, calibration, and data processing for protein polymerization measurements in living cells

    Science.gov (United States)

    Ströhl, Florian; Wong, Hovy H. W.; Holt, Christine E.; Kaminski, Clemens F.

    2018-01-01

    Fluorescence anisotropy imaging microscopy (FAIM) measures the depolarization properties of fluorophores to deduce molecular changes in their environment. For successful FAIM, several design principles have to be considered and a thorough system-specific calibration protocol is paramount. One important calibration parameter is the G factor, which describes the system-induced errors for different polarization states of light. The determination and calibration of the G factor is discussed in detail in this article. We present a novel measurement strategy, which is particularly suitable for FAIM with high numerical aperture objectives operating in TIRF illumination mode. The method makes use of evanescent fields that excite the sample with a polarization direction perpendicular to the image plane. Furthermore, we have developed an ImageJ/Fiji plugin, AniCalc, for FAIM data processing. We demonstrate the capabilities of our TIRF-FAIM system by measuring β -actin polymerization in human embryonic kidney cells and in retinal neurons.

  9. Simulated Fizeau ring fringes in transmission through spherical and plane reflected surfaces

    Science.gov (United States)

    Ramadan, W. A.; Wahba, H. H.

    2018-01-01

    In this paper, we present simulated Fizeau ring fringes. These fringes are constructed due to multiple reflection between highly reflected partially transmitted spherical and plane surfaces. The real paths of rays and consequently their amplitudes and phases have been determined when they reached the image plane. This plane is located at a certain distance above the interferometer. In these calculations, the impact of the image plane position, the radius of the spherical surface and the distance between the two surfaces on the fringe intensity distribution are investigated. A quite interesting result of our calculation is that the number of the interfered rays is varied and could be only two, even for a highly reflected surfaces. Three different estimated visualizations are included to give an overview imagination of the impact of the different parameter variation. These could be helpful for researchers for testing of spherical surfaces using interference-based methods.

  10. Reflection of diffuse light from dielectric one-dimensional rough surfaces.

    Science.gov (United States)

    González-Alcalde, Alma K; Méndez, Eugenio R; Terán, Emiliano; Cuppo, Fabio L S; Olivares, J A; García-Valenzuela, Augusto

    2016-03-01

    We study the reflection of diffuse light from 1D randomly rough dielectric interfaces. Results for the reflectance under diffuse illumination are obtained by rigorous numerical simulations and then contrasted with those obtained for flat surfaces. We also explore the possibility of using perturbation theories and conclude that they are limited for this type of study. Numerical techniques based on Kirchhoff approximation and reduced Rayleigh equations yield better results. We find that, depending on the refractive index contrast and nature of the irregularities, the roughness can increase or decrease the diffuse reflectance of the surface.

  11. NPP/VIIRS Atmospherically Corrected Surface Reflectance 6-Min L2 Swath 375m, 750m NRT

    Data.gov (United States)

    National Aeronautics and Space Administration — The VNP09_NRT is a Near Real Time (NRT) S-NPP/VIIRS 375 m, 750 m Atmospherically Corrected Surface Reflectance product. The NPP/VIIRS surface reflectance products...

  12. MODIS/Aqua Near Real Time (NRT) Surface Reflectance Daily L2G Global 250m SIN Grid

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS Near Real Time (NRT) Surface Reflectance products are an estimate of the surface spectral reflectance as it would be measured at ground level in the...

  13. VIIRS/NPP Surface Reflectance Daily L2G Global 1km and 500m SIN Grid V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The Visible Infrared Imaging Radiometer Suite (VIIRS) daily surface reflectance (VNP09GA) Version 1 product provides an estimate of land surface reflectance from the...

  14. The sparkle of the eye: the impact of ocular surface wetness on corneal light reflection.

    Science.gov (United States)

    Goto, Eiki; Dogru, Murat; Sato, Enrique Adan; Matsumoto, Yukihiro; Takano, Yoji; Tsubota, Kazuo

    2011-04-01

    To measure the sparkle of the human eye evaluated by the intensity of corneal light reflection in normal subjects and dry eye patients to investigate whether ocular surface wetness has an impact on the sparkle of the eye. Prospective case-control study. We examined a consecutive series of eight dry eye patients with Sjögren syndrome (SS, 15 eyes), as well as eight normal subjects (16 eyes). The specular corneal surface light reflection was quantitatively measured with an ophthalmic slit-lamp microscope and image capturing system under fixed conditions of light source, incident angle, and detector sensitivity. The intensity of images from subjects' corneal light reflection was quantified with image analysis software along with the measurement of grade of self-reported brilliancy of the eye, corneal fluorescein staining score, tear film break-up time, and Schirmer test value. The intensity of corneal light reflection was also compared before and after dry eye treatment. The mean intensity of corneal light reflection was significantly lower in dry eye patients (125.0 ± 40.1) than normal subjects (167.6 ± 36.6, P=.004). Grade of self-reported brilliancy of the eye, corneal fluorescein staining scores, tear film break-up time, and Schirmer test values showed good correlation to the intensity of corneal light reflection. After punctal plug treatment, the intensity of corneal light reflection significantly increased from 125.0 ± 40.1 to 167.2 ± 45.0 (Plight reflection representing the sparkle of the eye was significantly more intense in normal subjects compared to dry eye patients, and was increased after punctal plug treatment. The intensity of corneal light reflection appeared to correlate well with tear film stability, volume, and ocular surface desiccation. We showed that tears contributed not only to ocular surface wetness but also to the extent of the light reflection from the eye. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Reflection of plane waves from free surface of a microstretch elastic ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The problem of reflection of plane waves from free surface of a microstretch elastic solid half-space is studied. The energy ratios for ... axis is taken normal to free surface in downward direction. The region z > 0 is occupied by linear ... Superposed dots on the right hand side of above equations denote the second partial ...

  16. LANL MTI calibration team experience

    Science.gov (United States)

    Bender, Steven C.; Atkins, William H.; Clodius, William B.; Little, Cynthia K.; Christensen, R. Wynn

    2004-01-01

    The Multispectral Thermal Imager (MTI) was designed as an imaging radiometer with absolute calibration requirements established by Department of Energy (DOE) mission goals. Particular emphasis was given to water surface temperature retrieval using two mid wave and three long wave infrared spectral bands, the fundamental requirement was a surface temperature determination of 1K at the 68% confidence level. For the ten solar reflective bands a one-sigma radiometric performance goal of 3% was established. In order to address these technical challenges a calibration facility was constructed containing newly designed sources that were calibrated at NIST. Additionally, the design of the payload and its onboard calibration system supported post launch maintenance and update of the ground calibration. The on-orbit calibration philosophy also included vicarious techniques using ocean buoys, playas and other instrumented sites; these became increasingly important subsequent to an electrical failure which disabled the onboard calibration system. This paper offers various relevant lessons learned in the eight-year process of reducing to practice the calibration capability required by the scientific mission. The discussion presented will include observations pertinent to operational and procedural issues as well as hardware experiences; the validity of some of the initial assumptions will also be explored.

  17. Temperature comparison of different reflective surfaces of a solar thermal collector

    Science.gov (United States)

    Koh, Yit Yan; Chua, Yaw Long; Chin, Kiat Keong

    2017-09-01

    With the rapid depletion of fossil fuels, the search for application of alternative energy sources becomes more important than ever before. Solar energy has been identified as one of the major renewable energy that will contribute to power generation is years to come. There are two major categories of solar energy applications. Solar thermal collector is one of it. This paper presents an investigation on the effect of different reflecting surfaces on solar thermal collector. Three different reflective surfaces were applied on the surface of the solar thermal collector. Data was collected and analyzed. From the results, the aluminum mirror sheet performed best.

  18. Reflections

    Directory of Open Access Journals (Sweden)

    Joanne Embree

    2001-01-01

    Full Text Available Ideally, editorials are written one to two months before publication in the Journal. It was my turn to write this one. I had planned to write the first draft the evening after my clinic on Tuesday, September 11. It didn't get done that night or during the next week. Somehow, the topic that I had originally chosen just didn't seem that important anymore as I, along my friends and colleagues, reflected on the changes that the events of that day were likely to have on our lives.

  19. Binary pseudo-random gratings and arrays for calibration of the modulation transfer function of surface profilometers: recent developments

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Samuel K.; Soldate, Paul; Anderson, Erik H.; Cambie, Rossana; Marchesini, Stefano; McKinney, Wanye R.; Takacs, Peter Z.; Voronov, Dmitry L.; Yashchuk, Valeriy V.

    2009-07-07

    The major problem of measurement of a power spectral density (PSD) distribution of the surface heights with surface profilometers arises due to the unknown Modulation Transfer Function (MTF) of the instruments. The MTF tends to distort the PSD at higher spatial frequencies. It has been suggested [Proc. SPIE 7077-7, (2007), Opt. Eng. 47 (7), 073602-1-5 (2008)] that the instrumental MTF of a surface profiler can be precisely measured using standard test surfaces based on binary pseudo-random (BPR) patterns. In the cited work, a one dimensional (1D) realization of the suggested method based on use of BPR gratings has been demonstrated. Here, we present recent achievements made in fabricating and using two-dimensional (2D) BPR arrays that allow for a direct 2D calibration of the instrumental MTF. The 2D BPRAs were used as standard test surfaces for 2D MTF calibration of the MicromapTM-570 interferometric microscope with all available objectives. The effects of fabrication imperfections on the efficiency of calibration are also discussed.

  20. Calibration of GOES-derived solar radiation data using a distributed network of surface measurements in Florida, USA

    Science.gov (United States)

    Sumner, David M.; Pathak, Chandra S.; Mecikalski, John R.; Paech, Simon J.; Wu, Qinglong; Sangoyomi, Taiye; Babcock, Roger W.; Walton, Raymond

    2008-01-01

    Solar radiation data are critically important for the estimation of evapotranspiration. Analysis of visible-channel data derived from Geostationary Operational Environmental Satellites (GOES) using radiative transfer modeling has been used to produce spatially- and temporally-distributed datasets of solar radiation. An extensive network of (pyranometer) surface measurements of solar radiation in the State of Florida has allowed refined calibration of a GOES-derived daily integrated radiation data product. This refinement of radiation data allowed for corrections of satellite sensor drift, satellite generational change, and consideration of the highly-variable cloudy conditions that are typical of Florida. To aid in calibration of a GOES-derived radiation product, solar radiation data for the period 1995–2004 from 58 field stations that are located throughout the State were compiled. The GOES radiation product was calibrated by way of a three-step process: 1) comparison with ground-based pyranometer measurements on clear reference days, 2) correcting for a bias related to cloud cover, and 3) deriving month-by-month bias correction factors. Pre-calibration results indicated good model performance, with a station-averaged model error of 2.2 MJ m–2 day–1 (13 percent). Calibration reduced errors to 1.7 MJ m–2 day–1 (10 percent) and also removed time- and cloudiness-related biases. The final dataset has been used to produce Statewide evapotranspiration estimates.

  1. Estimates of radiance reflected towards the zenith at the surface of the sea

    Directory of Open Access Journals (Sweden)

    E. Aas

    2010-10-01

    Full Text Available Remote sensing of water colour by ship-mounted sensors represents an important tool for the validation of satellite products and the monitoring of water quality. The recorded radiance from the sea has to be corrected for the surface-reflected radiance from sun and sky in order to obtain the water-leaving radiance. Here the simple case of radiance reflected towards the zenith is studied. A set of observed sky radiance and solar irradiance data from Oslo has been used together with a Gaussian slope distribution for the sea surface in order to estimate the reflected radiance. The spectral range studied is 405–650 nm, the solar zenith angles are in the range 37°–76°, and the wind speeds are up to 10 m s−1. The analysis of the results show that the reflected radiance has to be separated into three contributions: sky radiance and sun rays reflected at the foam-free surface and irradiance reflected by whitecaps and foam. It is then demonstrated that by using four input values, namely the downward irradiance, the sky radiance from the zenith, the solar zenith angle and the wind speed, it is possible to obtain by simple expressions estimates of the reflected radiance that only differ from the former calculated values by relative errors of less than 5%. The analysis also indicates that for the spectral range studied neither the water-leaving radiance nor the surface-reflected radiance can be disregarded relative to the other one in the Case 2 waters of the Oslofjord-Skagerrak area. The results form a first step towards the study of reflected radiance in viewing angles differing from the nadir direction.

  2. Suppressing light reflection from polycrystalline silicon thin films through surface texturing and silver nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Akhter, Perveen [Department of Physics, University at Albany-SUNY, Albany, New York 12222 (United States); Huang, Mengbing, E-mail: mhuang@albany.edu; Kadakia, Nirag; Spratt, William; Malladi, Girish; Bakhru, Hassarum [SUNY College of Nanoscale Science and Engineering, Albany, New York 12203 (United States)

    2014-09-21

    This work demonstrates a novel method combining ion implantation and silver nanostructures for suppressing light reflection from polycrystalline silicon thin films. Samples were implanted with 20-keV hydrogen ions to a dose of 10¹⁷/cm², and some of them received an additional argon ion implant to a dose of 5×10¹⁵ /cm² at an energy between 30 and 300 keV. Compared to the case with a single H implant, the processing involved both H and Ar implants and post-implantation annealing has created a much higher degree of surface texturing, leading to a more dramatic reduction of light reflection from polycrystalline Si films over a broadband range between 300 and 1200 nm, e.g., optical reflection from the air/Si interface in the AM1.5 sunlight condition decreasing from ~30% with an untextured surface to below 5% for a highly textured surface after post-implantation annealing at 1000°C. Formation of Ag nanostructures on these ion beam processed surfaces further reduces light reflection, and surface texturing is expected to have the benefit of diminishing light absorption losses within large-size (>100 nm) Ag nanoparticles, yielding an increased light trapping efficiency within Si as opposed to the case with Ag nanostructures on a smooth surface. A discussion of the effects of surface textures and Ag nanoparticles on light trapping within Si thin films is also presented with the aid of computer simulations.

  3. Methods of creating solar-reflective nonwhite surfaces and their application to residential roofing materials

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen; Berdahl, Paul; Akbari, Hashem [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Miller, William [Oak Ridge National Laboratory, PO Box 2008, MS6070, Oak Ridge, TN 37831 (United States); Joedicke, Ingo [ISP Mineral Products, Inc., 34 Charles St., Hagerstown, MD 21740 (United States); Reilly, Joseph [American Rooftile Coatings, 250 Viking Avenue, Brea, CA 92821 (United States); Suzuki, Yoshi [MCA Clay Tile, 1985 Sampson Avenue, Corona, CA 92879 (United States); Vondran, Michelle [Steelscape Inc., 1200 Arrow Route, Rancho Cucamonga, CA 91730 (United States)

    2007-02-15

    We describe methods for creating solar-reflective nonwhite surfaces and their application to a wide variety of residential roofing materials, including metal, clay tile, concrete tile, wood, and asphalt shingle. Reflectance in the near-infrared (NIR) spectrum (0.7-2.5{mu}m) is maximized by coloring a topcoat with pigments that weakly absorb and (optionally) strongly backscatter NIR radiation, and by adding an NIR-reflective basecoat (e.g., one colored with titanium dioxide rutile white) if both the topcoat and the substrate weakly reflect NIR radiation. Coated steel and glazed clay-tile roofing products achieved NIR reflectances of up to 0.50 and 0.75, respectively, using only cool topcoats. Gray-cement concrete tiles achieved NIR reflectances as high as 0.60 with coatings colored by NIR-scattering pigments. Such tiles could attain NIR reflectances of up to 0.85 by overlaying a white basecoat with a topcoat colored by NIR-transparent organic pigments. Granule-surfaced asphalt shingles achieved NIR reflectances as high as 0.45 when the granules were covered with a white basecoat and a cool color topcoat. (author)

  4. Ultrasonic calibration assembly

    International Nuclear Information System (INIS)

    1981-01-01

    Ultrasonic transducers for in-service inspection of nuclear reactor vessels have several problems associated with them which this invention seeks to overcome. The first is that of calibration or referencing a zero start point for the vertical axis of transducer movement to locate a weld defect. The second is that of verifying the positioning (vertically or at a predetermined angle). Thirdly there is the problem of ascertaining the speed per unit distance in the operating medium of the transducer beam prior to the actual inspection. The apparatus described is a calibration assembly which includes a fixed, generally spherical body having a surface for reflecting an ultrasonic beam from one of the transducers which can be moved until the reflection from the spherical body is the highest amplitude return signal indicating radial alignment from the body. (U.K.)

  5. Sensitivity analysis of 6S-based look-up table for surface reflectance retrieval

    Science.gov (United States)

    Lee, Chang Suk; Yeom, Jong Min; Lee, Han Lim; Kim, Jae-Jin; Han, Kyung-Soo

    2015-02-01

    We created a look-up table (LUT) based on the Second Simulation of the Satellite Signal in the Solar Spectrum (6S) radiative transfer model, which reduces large errors in the surface reflectance retrieval under high solar zenith angle (SZA) conditions. The LUT was calculated in 10° SZA intervals containing pre-computed atmospheric correction coefficients as a function of discretized pre-defined input parameters. In order to validate the performance of the LUT, we compared the retrieved surface reflectance using the LUT against a retrieval performed using the simplified method of atmospheric correction (SMAC). These results were validated against MODIS reflectance data (MOD09). The surface reflectance obtained using the LUT was highly correlated with the MOD09, with a coefficient of determination (R2) of 0.88 (red band) and 0.94 (NIR). The retrieved surface reflectance had a root mean-squared error of 0.0132 (red band) and 0.0191 (NIR). Accuracy of surface reflectance retrieved using our LUT with a 10° SZA interval was better than that of the obtained using SMAC. However, certain errors were still present particularly at high SZAs. In order to increase the accuracy at high SZAs, new LUT was computed with a finer SZA interval (5°) at high SZAs. In both red and NIR bands, the R2, fine SZA interval LUT (0.92) were compared to the coarse SZA interval LUT (0.74) of around 65°. Additionally, the run time for surface reflectance retrievals with our LUT was almost comparable to that of the SMAC, an operational model. This study demonstrates that proper SZAs interval for making LUT in high SZA range.

  6. Iterative discrete ordinates solution of the equation for surface-reflected radiance

    Science.gov (United States)

    Radkevich, Alexander

    2017-11-01

    This paper presents a new method of numerical solution of the integral equation for the radiance reflected from an anisotropic surface. The equation relates the radiance at the surface level with BRDF and solutions of the standard radiative transfer problems for a slab with no reflection on its surfaces. It is also shown that the kernel of the equation satisfies the condition of the existence of a unique solution and the convergence of the successive approximations to that solution. The developed method features two basic steps: discretization on a 2D quadrature, and solving the resulting system of algebraic equations with successive over-relaxation method based on the Gauss-Seidel iterative process. Presented numerical examples show good coincidence between the surface-reflected radiance obtained with DISORT and the proposed method. Analysis of contributions of the direct and diffuse (but not yet reflected) parts of the downward radiance to the total solution is performed. Together, they represent a very good initial guess for the iterative process. This fact ensures fast convergence. The numerical evidence is given that the fastest convergence occurs with the relaxation parameter of 1 (no relaxation). An integral equation for BRDF is derived as inversion of the original equation. The potential of this new equation for BRDF retrievals is analyzed. The approach is found not viable as the BRDF equation appears to be an ill-posed problem, and it requires knowledge the surface-reflected radiance on the entire domain of both Sun and viewing zenith angles.

  7. Polydiagnostic calibration performed on a low pressure surface wave sustained argon plasma

    Science.gov (United States)

    de Vries, N.; Palomares, J. M.; Iordanova, E. I.; van Veldhuizen, E. M.; van der Mullen, J. J. A. M.

    2008-10-01

    The electron density and electron temperature of a low pressure surface wave sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined more precisely. The electron density, ne, is determined with Thomson scattering (TS), absolute continuum measurements, Stark broadening and an extrapolation of the atomic state distribution function (ASDF). The electron temperature, Te, is obtained using TS and absolute line intensity (ALI) measurements combined with a collisional-radiative (CR) model for argon. At an argon pressure of 15 mbar, the ne values obtained with TS and Stark broadening agree with each other within the error bars and are equal to (4 ± 0.5) × 1019 m-3, whereas the ne value (2 ± 0.5) × 1019 m-3 obtained from the continuum is about 30% lower. This suggests that the used formula and cross-section values for the continuum method have to be reconsidered. The electron density determined by means of extrapolation of the ASDF to the continuum is too high (~1020 m-3). This is most probably related to the fact that the plasma is strongly ionizing so that the extrapolation method is not justified. At 15 mbar, the Te values obtained with TS are equal to 13 400 ± 1100 K while the ALI/CR-model yields an electron temperature that is about 10% lower. It can be concluded that the passive results are in good or fair agreement with the active results. Therefore, the calibrated passive methods can be applied to other plasmas in a similar regime for which active diagnostic techniques cannot be used.

  8. Polydiagnostic calibration performed on a low pressure surface wave sustained argon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Vries, N de; Iordanova, E I; Van Veldhuizen, E M; Mullen, J J A M van der [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Palomares, J M [Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain)], E-mail: j.j.a.m.v.d.Mullen@tue.nl

    2008-10-21

    The electron density and electron temperature of a low pressure surface wave sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined more precisely. The electron density, n{sub e}, is determined with Thomson scattering (TS), absolute continuum measurements, Stark broadening and an extrapolation of the atomic state distribution function (ASDF). The electron temperature, T{sub e}, is obtained using TS and absolute line intensity (ALI) measurements combined with a collisional-radiative (CR) model for argon. At an argon pressure of 15 mbar, the n{sub e} values obtained with TS and Stark broadening agree with each other within the error bars and are equal to (4 {+-} 0.5) x 10{sup 19} m{sup -3}, whereas the n{sub e} value (2 {+-} 0.5) x 10{sup 19} m{sup -3} obtained from the continuum is about 30% lower. This suggests that the used formula and cross-section values for the continuum method have to be reconsidered. The electron density determined by means of extrapolation of the ASDF to the continuum is too high ({approx}10{sup 20} m{sup -3}). This is most probably related to the fact that the plasma is strongly ionizing so that the extrapolation method is not justified. At 15 mbar, the T{sub e} values obtained with TS are equal to 13 400 {+-} 1100 K while the ALI/CR-model yields an electron temperature that is about 10% lower. It can be concluded that the passive results are in good or fair agreement with the active results. Therefore, the calibrated passive methods can be applied to other plasmas in a similar regime for which active diagnostic techniques cannot be used.

  9. Analysis of calibrated sea clutter and boat reflectivity data at C- and X-band in South African coastal waters

    CSIR Research Space (South Africa)

    Herselman, PLR

    2007-10-01

    Full Text Available The temporal characteristics of low grazing angle sea clutter and boat reflectivity are considered for both fixed and stepped frequency waveforms under a range of environmental conditions and geometrical configurations. Detectability of boats using...

  10. Response-surface fits and calibration transfer for the correction of the oxygen effect in the quantification of carbon dioxide via FTIR spectroscopy.

    Science.gov (United States)

    Seichter, Felicia; Vogt, Josef; Radermacher, Peter; Mizaikoff, Boris

    2017-06-15

    During routine Fourier-Transform Infrared Spectroscopy (FTIR) based quantification of carbon dioxide in breath, it is necessary to account for a non-linear signal response to the analyte concentration and disturbance factors arising from the gas background matrix. These factors as well as day-to-day fluctuation should be corrected via calibration. We present a novel strategy to combine the information of previous calibrations with a minimal number of actual calibration measurements to obtain a precise calibration. After decomposition of the FTIR spectra via principal component analysis (PCA) into scores (corresponding to intensity) and loadings (corresponding to spectral curves), an empirical response surface fit equation between scores, analyte concentration and disturbance factors is established. The fit equation can be characterized via the coefficients determined by calibration. Out of a pool of coefficients gained from several calibrations, a multivariate inter-day distribution is generated. By requiring the coefficient set of the actual calibration to be a sample of the multivariate inter-day distribution, the number of necessary routine calibration samples is reduced to two. The corresponding coefficients are determined using the Lagrange Multipliers approach and the inter-day variability of coefficients is estimated using Bayesian statistics and Hierarchical models. The best calibration parameters in terms of calibration equation, wavelength region, preprocessing options and choice of routine calibration samples were determined; optimized for minimal number of calibration samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Surface reflectance of Antarctic bryophytes and protection from UV and visible light

    International Nuclear Information System (INIS)

    Robinson, S.A.; Wasley, J.; Turnbull, J.

    2000-01-01

    Full text: As well as determining the amount of solar radiation available for photosynthesis, the surface reflectance and absorptance characteristics of plants are their first defence against damaging effects of solar radiation. The solar spectrum can be damaging to plants in many ways. At shorter wavelengths, UV-B (280-320 nm) radiation can cause lesions in nucleic acid and proteins. Excess levels of visible radiation (400-750) can cause photoinhibition whilst high absorbtance of longer wavelengths (>750) leads to increases in temperature that can be detrimental in some environments. The adaptation of surface reflectance properties of vascular plants to particular environments are well known in some ecosystems. For example in desert ecosystems pubescent leaf surfaces that increase reflectance are common and have been demonstrated to be important to protection from photoinhibition. The epidermal characteristics of some plants are also known to change in absorptance, due to the accumulation of specific compounds. For example flavonoids which are effective screens against UV-B radiation, increase upon exposure to UV-B radiation. In this study we surveyed the natural variability in surface reflectance in mosses growing in continental Antarctica. Antarctica is experiencing large increases in incident UV-B radiation due to reductions in concentrations of stratospheric ozone. Additionally over the summer months (November January), when moss is exposed to direct sunlight, levels of visible solar radiation are also high, increasing the likelihood of photoinhibitory damage in moss. Our aim in this study is to describe the natural variability in the surface reflectance characteristics of moss, such that we have a baseline with which to assess future changes in response to changes in global climate, and imposed experimental treatments, and also to develop hypotheses with respect to how mosses have adapted to the cold and arid antarctic environment. Variability in surface

  12. Application of the complex cepstrum to the location of acoustic sources near reflective surfaces

    Science.gov (United States)

    Fuller, C. R.; Tavakkoli, S.; Elliott, K. B.; Hurst, C. J.; Obrien, W. F.

    1987-01-01

    The complex cepstrum is used to correct bearing estimations of acoustic sources in the presence of a reflective surface. An automated liftering procedure is used which zeros out a block portion of the cepstrum including the echo information. The problem of the resulting distortion is alleviated by applying a coherence criterion to the recovered direct signals at each microphone. Thus to a large degree the interactive nature of cepstral processing is overcome for this application. For the test signals and geometries considered the cepstrum is shown to accurately correct for bearing errors in acoustic signals contaminated with reflections from nearby surfaces.

  13. Selection of representative calibration sample sets for near-infrared reflectance spectroscopy to predict nitrogen concentration in grasses

    DEFF Research Database (Denmark)

    Shetty, Nisha; Rinnan, Åsmund; Gislum, René

    2012-01-01

    squares regression (PLSR), a chemometric method, has been applied on NIR spectroscopy data for the determination of the nitrogen (N) concentration in these grass samples. The sample selection method based on NIR spectral data proposed by Puchwein and the CADEX (computer aided design of experiments......) and interaction (cultivar × year fixed) random procedures to see the influence of different factors on sample selection. Puchwein's method performed best with lowest RMSEP followed by CADEX, interaction random, year random, cultivar random and complete random. Out of 118 samples of the complete calibration set...

  14. Numerical study of three-dimensional sound reflection from corrugated surface waves.

    Science.gov (United States)

    Choo, Youngmin; Song, H C; Seong, Woojae

    2016-10-01

    When a sound wave propagates in a water medium bounded by a smooth surface wave, reflection from a wave crest can lead to focusing and result in rapid variation of the received waveform as the surface wave moves [Tindle, Deane, and Preisig, J. Acoust. Soc. Am. 125, 66-72 (2009)]. In prior work, propagation paths have been constrained to be in a plane parallel to the direction of corrugated surface waves, i.e., a two-dimensional (2-D) propagation problem. In this paper, the azimuthal dependence of sound propagation as a three-dimensional (3-D) problem is investigated using an efficient, time-domain Helmholtz-Kirchhoff integral formulation. When the source and receiver are in the plane orthogonal to the surface wave direction, the surface wave curvature vanishes in conventional 2-D treatments and the flat surface simply moves up and down, resulting in minimal temporal variation of the reflected signal intensity. On the other hand, the 3-D propagation analysis reveals that a focusing phenomenon occurs in the reflected signal due to the surface wave curvature formed along the orthogonal plane, i.e., out-of-plane scattering.

  15. Comparison and uncertainty evaluation of different calibration protocols and ionization chambers for low-energy surface brachytherapy dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Candela-Juan, C., E-mail: ccanjuan@gmail.com [Radiation Oncology Department, La Fe University and Polytechnic Hospital, Valencia 46026 (Spain); Vijande, J. [Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, Burjassot 46100, Spain and Instituto de Física Corpuscular (UV-CSIC), Paterna 46980 (Spain); García-Martínez, T. [Radiation Oncology Department, Hospital La Ribera, Alzira 46600 (Spain); Niatsetski, Y.; Nauta, G.; Schuurman, J. [Elekta Brachytherapy, Veenendaal 3905 TH (Netherlands); Ouhib, Z. [Radiation Oncology Department, Lynn Regional Cancer Center, Boca Raton Community Hospital, Boca Raton, Florida 33486 (United States); Ballester, F. [Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Perez-Calatayud, J. [Radiation Oncology Department, La Fe University and Polytechnic Hospital, Valencia 46026, Spain and Department of Radiotherapy, Clínica Benidorm, Benidorm 03501 (Spain)

    2015-08-15

    Purpose: A surface electronic brachytherapy (EBT) device is in fact an x-ray source collimated with specific applicators. Low-energy (<100 kVp) x-ray beam dosimetry faces several challenges that need to be addressed. A number of calibration protocols have been published for x-ray beam dosimetry. The media in which measurements are performed are the fundamental difference between them. The aim of this study was to evaluate the surface dose rate of a low-energy x-ray source with small field applicators using different calibration standards and different small-volume ionization chambers, comparing the values and uncertainties of each methodology. Methods: The surface dose rate of the EBT unit Esteya (Elekta Brachytherapy, The Netherlands), a 69.5 kVp x-ray source with applicators of 10, 15, 20, 25, and 30 mm diameter, was evaluated using the AAPM TG-61 (based on air kerma) and International Atomic Energy Agency (IAEA) TRS-398 (based on absorbed dose to water) dosimetry protocols for low-energy photon beams. A plane parallel T34013 ionization chamber (PTW Freiburg, Germany) calibrated in terms of both absorbed dose to water and air kerma was used to compare the two dosimetry protocols. Another PTW chamber of the same model was used to evaluate the reproducibility between these chambers. Measurements were also performed with two different Exradin A20 (Standard Imaging, Inc., Middleton, WI) chambers calibrated in terms of air kerma. Results: Differences between surface dose rates measured in air and in water using the T34013 chamber range from 1.6% to 3.3%. No field size dependence has been observed. Differences are below 3.7% when measurements with the A20 and the T34013 chambers calibrated in air are compared. Estimated uncertainty (with coverage factor k = 1) for the T34013 chamber calibrated in water is 2.2%–2.4%, whereas it increases to 2.5% and 2.7% for the A20 and T34013 chambers calibrated in air, respectively. The output factors, measured with the PTW chambers

  16. SU-F-BRA-09: New Efficient Method for Xoft Axxent Electronic Brachytherapy Source Calibration by Pre-Characterizing Surface Applicators

    Energy Technology Data Exchange (ETDEWEB)

    Pai, S [iCAD Inc., Los Gatos, CA (United States)

    2015-06-15

    Purpose: The objective is to improve the efficiency and efficacy of Xoft™ Axxent™ electronic brachytherapy (EBT) calibration of the source & surface applicator using AAPM TG-61 formalism. Methods: Current method of Xoft EBT source calibration involves determination of absolute dose rate of the source in each of the four conical surface applicators using in-air chamber measurements & TG61 formalism. We propose a simplified TG-61 calibration methodology involving initial characterization of surface cone applicators. This is accomplished by calibrating dose rates for all 4 surface applicator sets (for 10 sources) which establishes the “applicator output ratios” with respect to the selected reference applicator (20 mm applicator). After the initial time, Xoft™ Axxent™ source TG61 Calibration is carried out only in the reference applicator. Using the established applicator output ratios, dose rates for other applicators will be calculated. Results: 200 sources & 8 surface applicator sets were calibrated cumulatively using a Standard Imaging A20 ion-chamber in accordance with manufacturer-recommended protocols. Dose rates of 10, 20, 35 & 50mm applicators were normalized to the reference (20mm) applicator. The data in Figure 1 indicates that the normalized dose rate variation for each applicator for all 200 sources is better than ±3%. The average output ratios are 1.11, 1.02 and 0.49 for the 10 mm,35 mm and 50 mm applicators, respectively, which are in good agreement with the manufacturer’s published output ratios of 1.13, 1.02 and 0.49. Conclusion: Our measurements successfully demonstrate the accuracy of a new calibration method using a single surface applicator for Xoft EBT sources and deriving the dose rates of other applicators. The accuracy of the calibration is improved as this method minimizes the source position variation inside the applicator during individual source calibrations. The new method significantly reduces the calibration time to less

  17. In situ probing of surface hydrides on hydrogenated amorphous silicon using attenuated total reflection infrared spectroscopy

    CERN Document Server

    Kessels, W M M; Sanden, M C M; Aydil, E S

    2002-01-01

    An in situ method based on attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) is presented for detecting surface silicon hydrides on plasma deposited hydrogenated amorphous silicon (a-Si:H) films and for determining their surface concentrations. Surface silicon hydrides are desorbed by exposing the a-Si:H films to low energy ions from a low density Ar plasma and by comparing the infrared spectrum before and after this low energy ion bombardment, the absorptions by surface hydrides can sensitively be separated from absorptions by bulk hydrides incorporated into the film. An experimental comparison with other methods that utilize isotope exchange of the surface hydrogen with deuterium showed good agreement and the advantages and disadvantages of the different methods are discussed. Furthermore, the determination of the composition of the surface hydrogen bondings on the basis of the literature data on hydrogenated crystalline silicon surfaces is presented, and quantification of the h...

  18. Observation on Surface Change of Fragile Glass: Temperature - Time Dependence Studied by X-Ray Reflectivity

    International Nuclear Information System (INIS)

    Kikkawa, Hiroyuki; Kitahara, Amane; Takahashi, Isao

    2004-01-01

    The structural change of a fragile glass surface close to the glass transition temperature Tg is studied by using X-ray reflectivity. Measurements were performed on surfaces of maltitol, which is a typical polyalcohol fragile glass with Tg = 320K. Upon both heating and cooling, we find the following features which are also noticed in silicate glass surfaces: (i) On heating, the surface morphology indicates a variation at temperatures below Tg; (ii) A drastic increase in surface roughness occurs at a temperature about 333K on heating, which is 13K higher than Tg; (iii) During the cooling of the sample, formation of a low-density surface layer (3nm at 293K) is observed. Prior to the crystallization, nm - μm sized domains were grown at the surface, which might not be reported for other glasses

  19. Negligible water surface charge determined using Kelvin probe and total reflection X-ray fluorescence techniques.

    Science.gov (United States)

    Shapovalov, Vladimir L; Möhwald, Helmuth; Konovalov, Oleg V; Knecht, Volker

    2013-09-07

    The water surface charge has been extensively debated in recent decades. Electrophoretic mobilities of air bubbles in water and disjoining pressures between the surfaces of aqueous films suggest that the surface of water exhibits a significant negative charge. This is commonly attributed to a strong adsorption of hydroxide ions at the interface, though spectroscopic measurements and simulation studies suggest surface depletion of hydroxide ions. Alternatively, the negative surface charge could arise from surface contamination with trace charged surfactants. We have probed the variation in the surface charge of water with pH by measuring surface potentials using the Kelvin probe technique. Independently, the abundance in the interfacial layer of "reporter ions" (Rb(+) and Br(-)), which must be affected by a charged surface, has been monitored using the total reflection X-ray fluorescence (TRXF) technique. Special care was taken to prove the high sensitivity of this technique as well as to avoid surface contaminants. The magnitude of the surface charge was found to be below 1 e per 500 nm(2) (TRXF). No evidence of variations in the surface potential between pH 2-3 and pH 9-12 was detected within the accuracies of the methods (5 mV for Kelvin probe and 2 mV for TRXF). Hence, our findings suggest that the clean water surface exhibits negligible charge in a wide pH range.

  20. Calibration of the modulation transfer function of surface profilometers with binary pseudo-random test standards: expanding the application range

    Energy Technology Data Exchange (ETDEWEB)

    Yashchuk, Valeriy V.; Anderson, Erik H.; Barber, Samuel K.; Bouet, Nathalie; Cambie, Rossana; Conley, Raymond; McKinney, Wayne R.; Takacs, Peter Z.; Voronov, Dmitriy L.

    2011-03-14

    A modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays [Proc. SPIE 7077-7 (2007), Opt. Eng. 47, 073602 (2008)] has been proven to be an effective MTF calibration method for a number of interferometric microscopes and a scatterometer [Nucl. Instr. and Meth. A616, 172 (2010)]. Here we report on a further expansion of the application range of the method. We describe the MTF calibration of a 6 inch phase shifting Fizeau interferometer. Beyond providing a direct measurement of the interferometer's MTF, tests with a BPR array surface have revealed an asymmetry in the instrument's data processing algorithm that fundamentally limits its bandwidth. Moreover, the tests have illustrated the effects of the instrument's detrending and filtering procedures on power spectral density measurements. The details of the development of a BPR test sample suitable for calibration of scanning and transmission electron microscopes are also presented. Such a test sample is realized as a multilayer structure with the layer thicknesses of two materials corresponding to BPR sequence. The investigations confirm the universal character of the method that makes it applicable to a large variety of metrology instrumentation with spatial wavelength bandwidths from a few nanometers to hundreds of millimeters.

  1. Calibration of the modulation transfer function of surface profilometers with binary pseudo-random test standards: Expanding the application range

    Energy Technology Data Exchange (ETDEWEB)

    Yashchuk, Valeriy V; Anderson, Erik H.; Barber, Samuel K.; Bouet, Nathalie; Cambie, Rossana; Conley, Raymond; McKinney, Wayne R.; Takacs, Peter Z.; Voronov, Dmitriy L.

    2010-07-26

    A modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays [Proc. SPIE 7077-7 (2007), Opt. Eng. 47(7), 073602-1-5 (2008)] has been proven to be an effective MTF calibration method for a number of interferometric microscopes and a scatterometer [Nucl. Instr. and Meth. A 616, 172-82 (2010]. Here we report on a significant expansion of the application range of the method. We describe the MTF calibration of a 6 inch phase shifting Fizeau interferometer. Beyond providing a direct measurement of the interferometer's MTF, tests with a BPR array surface have revealed an asymmetry in the instrument's data processing algorithm that fundamentally limits its bandwidth. Moreover, the tests have illustrated the effects of the instrument's detrending and filtering procedures on power spectral density measurements. The details of the development of a BPR test sample suitable for calibration of scanning and transmission electron microscopes are also presented. Such a test sample is realized as a multilayer structure with the layer thicknesses of two materials corresponding to BPR sequence. The investigations confirm the universal character of the method that makes it applicable to a large variety of metrology instrumentation with spatial wavelength bandwidths from a few nanometers to hundreds of millimeters.

  2. Calibration of the modulation transfer function of surface profilometers with binary pseudo-random test standards: expanding the application range

    International Nuclear Information System (INIS)

    Yashchuk, Valeriy V.; Anderson, Erik H.; Barber, Samuel K.; Bouet, Nathalie; Cambie, Rossana; Conley, Raymond; McKinney, Wayne R.; Takacs, Peter Z.; Voronov, Dmitriy L.

    2011-01-01

    A modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays (Proc. SPIE 7077-7 (2007), Opt. Eng. 47, 073602 (2008)) has been proven to be an effective MTF calibration method for a number of interferometric microscopes and a scatterometer (Nucl. Instr. and Meth. A616, 172 (2010)). Here we report on a further expansion of the application range of the method. We describe the MTF calibration of a 6 inch phase shifting Fizeau interferometer. Beyond providing a direct measurement of the interferometer's MTF, tests with a BPR array surface have revealed an asymmetry in the instrument's data processing algorithm that fundamentally limits its bandwidth. Moreover, the tests have illustrated the effects of the instrument's detrending and filtering procedures on power spectral density measurements. The details of the development of a BPR test sample suitable for calibration of scanning and transmission electron microscopes are also presented. Such a test sample is realized as a multilayer structure with the layer thicknesses of two materials corresponding to BPR sequence. The investigations confirm the universal character of the method that makes it applicable to a large variety of metrology instrumentation with spatial wavelength bandwidths from a few nanometers to hundreds of millimeters.

  3. High-resolution x-ray scatter and reflectivity study of sputtered IR surfaces

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Abdali, S.; Hornstrup, Allan

    1993-01-01

    In recent years there has been an increased interest in the possible use of Ir as the reflecting surface in X-ray telescope programs. An X-ray study of such surfaces produced by sputtering of Ir on highly polished Zerodur flats is presented here. The study was performed using Fe K(alpha) 1 (6...... result shows that an Ir coating can be produced with nominal bulk density....

  4. Near-surface 3D reflections seismic survey; Sanjigen senso hanshaho jishin tansa

    Energy Technology Data Exchange (ETDEWEB)

    Nakahigashi, H.; Mitsui, H.; Nakano, O.; Kobayashi, T. [DIA Consultants Co. Ltd., Tokyo (Japan)

    1997-05-27

    Faults are being actively investigated across Japan since the Great Hanshin-Awaji Earthquake. Discussed in this report is the application of the 3D near-surface reflection seismic survey in big cities. Data from trenching and drilling is used for the geological interpretation of the surroundings of a fault, and the reflection seismic survey is used to identify the position, etc., of the fault. In this article, when the results obtained from the experimental field are examined, it is found that the conventional 2D imaging reflection survey betrays the limit of its capability when the geological structure is complicated, that the 3D reflection seismic survey, on the contrary, is capable of high-precision imaging and, when augmented by drilling, etc., becomes capable of a more detailed interpretation, and that it also contributes effectively to the improvement of local disaster prevention in big cities. Using as the model the Tachikawa fault that runs near JR Tachikawa Station, embodiment of the 3D reflection seismic survey is reviewed. For the acquisition of data excellent in quality in a 3D reflection seismic survey conducted utilizing the roads in the sector chosen for experiment in the urban area, the shock generating points and receiving points should be positioned by taking into account the parameters in the bin arranging process so that the mid-points will be regularly distributed on the surface. 3 refs., 11 figs., 1 tab.

  5. LiDAR Relative Reflectivity Surface (2011) for Fish Bay, St. John

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a LiDAR (Light Detection & Ranging) 0.3x0.3 meter resolution relative seafloor reflectivity surface for Fish Bay, St. John in the U.S....

  6. LiDAR Relative Reflectivity Surface (2011) for Coral Bay, St. John

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a LiDAR (Light Detection & Ranging) 0.3x0.3 meter resolution relative seafloor reflectivity surface for Coral Bay, St. John in the U.S....

  7. Introducing a mini-catamaran to perform reflectance measurements above and below the water surface

    Science.gov (United States)

    Froidefond, Jean-Marie; Ouillon, Sylvain

    2005-02-01

    An innovative platform is tested to perform reflectance measurements at sea. This platform is a mini-catamaran with two hulls 1m long and set 0.7m apart, fitted with optical sensors. It can be used far away from an oceanographic ship to avoid its hull influencing the measurement. Reflectance measurements were performed with a TriOS radiance sensor placed +2cm or -2cm from the water surface and a TriOS irradiance sensor. Tests were carried out in calm seas and with cloud cover. The processing to derive marine radiances from raw measurements is detailed. When the radiance sensor is above the interface, it limits the sky reflections on the targeted surface and the radiance is identical to that deduced from measurements below the surface. When the sensor is placed at +3cm abovewater or higher, glint affects the measurements. The mini-catamaran shows a good ability to measure marine reflectance with an adapted measurement protocol. Except for very turbid waters, it seems preferable to perform upwelling radiance measurements below the surface.

  8. Total reflection PIXE (TPIXE) and RBS for surface and trace element analysis.

    NARCIS (Netherlands)

    van Kan, J.A.; Vis, R.D.

    1996-01-01

    MeV proton and α beams at small incident angles (0-35 mrad) were used to analyse flat surfaces such as Si wafers and coated quartz substrates. X-rays and backscattered particles were detected in a total reflection geometry. Using TPIXE a quick and simultaneous detection of different trace elements

  9. The normalization of surface anisotropy effects present in SEVIRI reflectances by using the MODIS BRDF method

    DEFF Research Database (Denmark)

    Proud, Simon Richard; Zhang, Qingling; Schaaf, Crystal

    2014-01-01

    A modified version of the MODerate resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF) algorithm is presented for use in the angular normalization of surface reflectance data gathered by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI......) aboard the geostationary Meteosat Second Generation (MSG) satellites. We present early and provisional daily nadir BRDF-adjusted reflectance (NBAR) data in the visible and near-infrared MSG channels. These utilize the high temporal resolution of MSG to produce BRDF retrievals with a greatly reduced...... acquisition period than the comparable MODIS products while, at the same time, removing many of the angular perturbations present within the original MSG data. The NBAR data are validated against reflectance data from the MODIS instrument and in situ data gathered at a field location in Africa throughout 2008...

  10. Suppressing light reflection from polycrystalline silicon thin films through surface texturing and silver nanostructures

    International Nuclear Information System (INIS)

    Akhter, Perveen; Huang, Mengbing; Kadakia, Nirag; Spratt, William; Malladi, Girish; Bakhru, Hassarum

    2014-01-01

    This work demonstrates a novel method combining ion implantation and silver nanostructures for suppressing light reflection from polycrystalline silicon thin films. Samples were implanted with 20-keV hydrogen ions to a dose of 10 17 /cm 2 , and some of them received an additional argon ion implant to a dose of 5 × 10 15 /cm 2 at an energy between 30 and 300 keV. Compared to the case with a single H implant, the processing involved both H and Ar implants and post-implantation annealing has created a much higher degree of surface texturing, leading to a more dramatic reduction of light reflection from polycrystalline Si films over a broadband range between 300 and 1200 nm, e.g., optical reflection from the air/Si interface in the AM1.5 sunlight condition decreasing from ∼30% with an untextured surface to below 5% for a highly textured surface after post-implantation annealing at 1000 °C. Formation of Ag nanostructures on these ion beam processed surfaces further reduces light reflection, and surface texturing is expected to have the benefit of diminishing light absorption losses within large-size (>100 nm) Ag nanoparticles, yielding an increased light trapping efficiency within Si as opposed to the case with Ag nanostructures on a smooth surface. A discussion of the effects of surface textures and Ag nanoparticles on light trapping within Si thin films is also presented with the aid of computer simulations.

  11. Methods of Creating Solar-Reflective Nonwhite Surfaces and theirApplication to Residential Roofing Materials

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen; Berdahl, Paul; Akbari, Hashem; Miller, William; Joedicke, Ingo; Reilly, Joseph; Suzuki, Yoshi; Vondran, Michelle

    2005-05-24

    We describe methods for creating solar-reflective nonwhitesurfaces and their application to a wide variety of residential roofingmaterials, including metal, clay tile, concrete tile, wood, and asphaltshingle. Reflectance in the near-infrared (NIR) spectrum (0.7 2.5mu m) ismaximized by coloring a topcoatwith pigments that weakly absorb and(optionally) strongly backscatter NIR radiation, and adding anNIR-reflective basecoat (e.g., titanium dioxide white) if both thetopcoat and substrate weakly reflect NIR radiation. Coated steel andglazed clay tile roofing products achieved NIRreflectances of up to 0.50and 0.75, respectively, using only cool topcoats. Gray concrete tilesachieve NIR reflectances as high as 0.60 when thickly coated withNIR-scattering pigments, and could attain an NIR reflectances as high as0.85 by overlaying a titanium-dioxide basecoat with a topcoat colored byNIR-transparent organic pigments. Granule-surfaced asphalt shinglesachieved NIR reflectances as high as 0.45 when a cool color topcoat wasapplied over a thick white basecoat.

  12. A problem finding in calibration of Si(Au) surface-barrier semiconductor detector and a simple resolved method

    International Nuclear Information System (INIS)

    Song Zhangyong; Ruan Fangfang; Lu Rongchun; Chinese Academy of Sccience, Beijing; Yang Zhihu; Tan Jilian; Shao Caojie; Cai Xiaohong; Zhang Hongqiang; Shao Jianxiong; Cui Ying; Xie Jiangshan; Gao Zhimin

    2007-01-01

    In calibration of Si(Au) surface-barrier semiconductor detector, we find the peak-channel of 241 Am standard radioactive source shift with the position and the size of incident window. The reason may be result from the non-uniformity of Au-layer plated on Si-layer, because it may increase the probability of electron-vacancy pair recombination, but the exact reason is not clear. Dut to this problem is disadvantage to heavy ion-atom impact experiment; we resolve it by fixing up the position and the size of incident window and calibrating two sets of spectrometers, which placed symmetrically in the target room. Thus, this two set of apparatus can measure the back-scattered ions simultaneously in ion-atom impact experiment. We could obtain reliable experimental results by comparing with the two back-scattering spectra. (authors)

  13. Lactoperoxidase catalyzed radioiodination of cell surface immunoglobulin: incorporated radioactivity may not reflect relative cell surface Ig density

    International Nuclear Information System (INIS)

    Wilder, R.L.; Yuen, C.C.; Mage, R.G.

    1979-01-01

    Rabbit and mouse splenic lymphocytes were radioiodinated by the lactoperoxidase technique, extracted with non-ionic detergent, immunoprecipitated with high titered rabbit anti-kappa antisera, and compared by SDS-PAGE. Mouse sIg peaks were reproducibly larger in size than rabbit sIg peaks (often greater than 10 times). Neither differences in incorporation of label into the rabbit cell surface, nor differences in average sIg density explain this result. Total TCA-precipitable radioactivity was similar in each species. Estimation of the relative amounts of sIg in the mouse and rabbit showed similar average sIg densities. Differences in detergent solubility, proteolytic lability, or antisera used also do not adequately account for this difference. Thus, these data indicate that radioactivity incorporated after lactoperoxidase catalyzed cell surface radioiodination may not reflect cell surface Ig density. Conclusions about cell surface density based upon relative incorporation of radioactivity should be confirmed by other approaches

  14. Critical coupling of surface plasmons in graphene attenuated total reflection geometry

    Energy Technology Data Exchange (ETDEWEB)

    Cuevas, Mauro, E-mail: cuevas@df.uba.ar [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Facultad de Ingeniería y Tecnología Informática, Universidad de Belgrano, Villanueva 1324, C1426BMJ, Buenos Aires (Argentina); Grupo de Electromagnetismo Aplicado, Departamento de Física, FCEN, Universidad de Buenos Aires and IFIBA, Ciudad Universitaria, Pabellón I, C1428EHA, Buenos Aires (Argentina)

    2016-12-09

    We study the optical response of an attenuated total reflection (ATR) structure in Otto configuration with graphene sheet, paying especial attention to the occurrence of total absorption. Our results show that due to excitation of surface plasmons on the graphene sheet, two different conditions of total absorption may occur. At these conditions, the energy loss of the surface plasmon by radiation is equal to its energy loss by absorption into the graphene sheet. We give necessary conditions on ATR parameters for the existence of total absorption. - Highlights: • Attenuated total reflection (ATR) structure with graphene sheet. • Surface plasmons and power matched condition. • Necessary conditions on ATR parameters for the existence of total absorption.

  15. A compact ESPI system for displacement measurements of specular reflecting or optical rough surfaces

    DEFF Research Database (Denmark)

    Hansen, R.S.

    2004-01-01

    A stable and compact speckle interferometer for doing out-of-plane displacement measurements on reflective as well as diffusely scattering object surfaces is demonstrated. The set-up is based on a nearly path length compensated interferometer of the Fizeau type and uses diffuse illumination...... of the object combined with a speckled reference wave. This combination eliminates the need for special optical components, and the interferometer can be built of commonly available components. The diffuse illumination wave is obtained by scattering coherent light from a diffusely scattering surface....... The speckled reference wave is established by reflecting a part of the diffuse illumination wave from a glass plate placed in front of the object. Besides relaxing the alignment tolerances of the set-up, the diffuse illumination eliminates the need for any preparation of the surface under test, which turns...

  16. Intensity distributions of reflected surface channeling protons scattered on surfaces of electron-bombarded alkali halide crystals

    Science.gov (United States)

    Fukazawa, Y.; Kihara, K.; Iwamoto, K.; Susuki, Y.

    2013-11-01

    We have examined the surface-channeling of 550 keV protons on electron-bombarded KBr(0 0 1) surfaces at grazing incidence. On the surface, electron-stimulated desorption (ESD) resulting from the irradiation of 5 keV electrons changes the surface morphology. In order to investigate the change of the surface morphology, the luminous intensity distributions observed on a fluorescent screen (scattering patterns) of the reflected protons under the surface-channeling conditions are measured. Normalized specular intensity of the protons oscillates, and the results of computer simulations show that the period of the intensity oscillation agrees with the period of layer-by-layer desorption. The measured period of the oscillation is comparable to the simulated one, i.e., the period of the desorption, however, the measured amplitude of the oscillation is weak. This shows that the layer-by-layer desorption of the experimental surface is observed but is not as remarkable as that of the perfect surface introduced in the simulation.

  17. Intensity distributions of reflected surface channeling protons scattered on surfaces of electron-bombarded alkali halide crystals

    Energy Technology Data Exchange (ETDEWEB)

    Fukazawa, Y., E-mail: yukofu@cc.osaka-kyoiku.ac.jp; Kihara, K.; Iwamoto, K.; Susuki, Y.

    2013-11-15

    We have examined the surface-channeling of 550 keV protons on electron-bombarded KBr(0 0 1) surfaces at grazing incidence. On the surface, electron-stimulated desorption (ESD) resulting from the irradiation of 5 keV electrons changes the surface morphology. In order to investigate the change of the surface morphology, the luminous intensity distributions observed on a fluorescent screen (scattering patterns) of the reflected protons under the surface-channeling conditions are measured. Normalized specular intensity of the protons oscillates, and the results of computer simulations show that the period of the intensity oscillation agrees with the period of layer-by-layer desorption. The measured period of the oscillation is comparable to the simulated one, i.e., the period of the desorption, however, the measured amplitude of the oscillation is weak. This shows that the layer-by-layer desorption of the experimental surface is observed but is not as remarkable as that of the perfect surface introduced in the simulation.

  18. Probing Ultrafast Electron Dynamics at Surfaces Using Soft X-Ray Transient Reflectivity Spectroscopy

    Science.gov (United States)

    Baker, L. Robert; Husek, Jakub; Biswas, Somnath; Cirri, Anthony

    The ability to probe electron dynamics with surface sensitivity on the ultrafast time scale is critical for understanding processes such as charge separation, injection, and surface trapping that mediate efficiency in catalytic and energy conversion materials. Toward this goal, we have developed a high harmonic generation (HHG) light source for femtosecond soft x-ray reflectivity. Using this light source we investigated the ultrafast carrier dynamics at the surface of single crystalline α-Fe2O3, polycrystalline α-Fe2O3, and the mixed metal oxide, CuFeO2. We have recently demonstrated that CuFeO2 in particular is a selective catalyst for photo-electrochemical CO2 reduction to acetate; however, the role of electronic structure and charge carrier dynamics in mediating catalytic selectivity has not been well understood. Soft x-ray reflectivity measurements probe the M2,3, edges of the 3d transition metals, which provide oxidation and spin state resolution with element specificity. In addition to chemical state specificity, these measurements are also surface sensitive, and by independently simulating the contributions of the real and imaginary components of the complex refractive index, we can differentiate between surface and sub-surface contributions to the excited state spectrum. Accordingly, this work demonstrates the ability to probe ultrafast carrier dynamics in catalytic materials with element and chemical state specificity and with surface sensitivity.

  19. The effect of surface texture on total reflection of neutrons and X-rays from modified interfaces

    DEFF Research Database (Denmark)

    Goldar, A.; Roser, S.J.; Hughes, A.

    2002-01-01

    X-ray and neutron scattering from macroscopically rough surfaces and interfaces is considered and a new method of analysis based on the variation of the shape of the total reflection edge in the reflectivity profile is proposed. It was shown that in the limit that the correlation length...... and the height of the surface roughness are larger than the wavelength (at least 100 times bigger) of the incoming beam, the total reflection edge in the reflection profile becomes rounded. This technique allows direct analysis of the variation of the reflectivity pro le in terms of the structure of the surface...

  20. Evaluation of BRDF Archetypes for Representing Surface Reflectance Anisotropy Using MODIS BRDF Data

    Directory of Open Access Journals (Sweden)

    Hu Zhang

    2015-06-01

    Full Text Available Bidirectional reflectance distribution function (BRDF archetypes extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS BRDF/Albedo product over the global Earth Observing System Land Validation Core Sites can be used to simplify BRDF models. The present study attempts to evaluate the representativeness of BRDF archetypes for surface reflectance anisotropy. Five-year forward-modeled MODIS multi-angular reflectance (MCD-ref and aditional actual MODIS multi-angular observations (MCD-obs in four growing periods in 2008 over three tiles were taken as validation data. First, BRDF archetypes in the principal plane were qualitatively compared with the time-series MODIS BRDF product of randomly sampled pixels. Secondly, BRDF archetypes were used to fit MCD-ref, and the average root-mean-squared errors (RMSEs over each tile were examined for these five years. Finally, both BRDF archetypes and the MODIS BRDF were used to fit MCD-obs, and the histograms of the fit-RMSEs were compared. The consistency of the directional reflectance between the BRDF archetypes and MODIS BRDFs in nadir-view, hotspot and entire viewing hemisphere at 30° and 50° solar geometries were also examined. The results confirm that BRDF archetypes are representative of surface reflectance anisotropy for available snow-free MODIS data.

  1. Correlation characteristics of signals reflected by the wavy surface of ocean in mirror direction

    Science.gov (United States)

    Zhitkovskiy, Y. Y.; Nosov, A. V.; Savelyev, V. V.

    1985-06-01

    An experimental study was carried out to determine the correlation characteristics of pseudonoise signals reflected from a wave-covered surface in the mirror direction. The major measured quantity was the reciprocal correlation coefficient between the transmitted signal and the reflected signal. The transmitter was lowered from a ship on a 150 m cable. The receiver and preamplifier were lowered to the same depth from a buoy which was allowed to drift from the ship to a distance of 100-500 m, the changing distance changing the angle of the beam reflected from the surface of the ocean back down to the hydrophone. The radiator transmitted a pulsed signal with a pseudonoise carrier. The results were interpreted within the framework of ordinary correlation theory by processing several recordings, calculating the sign and ordinary correlation coefficients to determine the variation in sign correlation coefficient as a function of the ordinary correlation coefficient. Graphs of the average variation are presented. It was found that the medium did not distort the signal as it propagated through the water mass (within the limits of experimental accuracy). The correlation coefficient between the transmitted and reflected signals is thus determined entirely by the characteristics of reradiation of the sound by the wavecovered surface.

  2. Aerosol Optical Retrieval and Surface Reflectance from Airborne Remote Sensing Data over Land

    Directory of Open Access Journals (Sweden)

    Cristiana Bassani

    2010-06-01

    Full Text Available Quantitative analysis of atmospheric optical properties and surface reflectance can be performed by applying radiative transfer theory in the Atmosphere-Earth coupled system, for the atmospheric correction of hyperspectral remote sensing data. This paper describes a new physically-based algorithm to retrieve the aerosol optical thickness at 550nm (τ550 and the surface reflectance (ρ from airborne acquired data in the atmospheric window of the Visible and Near-Infrared (VNIR range. The algorithm is realized in two modules. Module A retrieves τ550 with a minimization algorithm, then Module B retrieves the surface reflectance ρ for each pixel of the image. The method was tested on five remote sensing images acquired by an airborne sensor under different geometric conditions to evaluate the reliability of the method. The results, τ550 and ρ, retrieved from each image were validated with field data contemporaneously acquired by a sun-sky radiometer and a spectroradiometer, respectively. Good correlation index, r, and low root mean square deviations, RMSD, were obtained for the τ550 retrieved by Module A (r2 = 0.75, RMSD = 0.08 and the ρ retrieved by Module B (r2 ≤ 0.9, RMSD ≤ 0.003. Overall, the results are encouraging, indicating that the method is reliable for optical atmospheric studies and the atmospheric correction of airborne hyperspectral images. The method does not require additional at-ground measurements about at-ground reflectance of the reference pixel and aerosol optical thickness.

  3. Characterizing the surface heterogeneity of fire effects using multi-temporal reflective wavelength data

    CSIR Research Space (South Africa)

    Roy, DP

    2005-10-10

    Full Text Available of fire effects using multi-temporal reflective wavelength data D. P. Roy a; T. Landmann ba Department of Geography, College Park, and NASA Goddard, Space Flight Center, University of Maryland. Code 614.5 (B32), Greenbelt, MD 20771. USAb CSIR Environmentek... Characterizing the surface heterogeneity of fire effects using multi-temporal reflective wavelength data D. P. ROY*{ and T. LANDMANN{ {Department of Geography, University of Maryland, College Park, and NASA Goddard, Space Flight Center, Code 614.5 (B32...

  4. Using Bayesian Model Averaging (BMA) to calibrate probabilistic surface temperature forecasts over Iran

    Energy Technology Data Exchange (ETDEWEB)

    Soltanzadeh, I. [Tehran Univ. (Iran, Islamic Republic of). Inst. of Geophysics; Azadi, M.; Vakili, G.A. [Atmospheric Science and Meteorological Research Center (ASMERC), Teheran (Iran, Islamic Republic of)

    2011-07-01

    Using Bayesian Model Averaging (BMA), an attempt was made to obtain calibrated probabilistic numerical forecasts of 2-m temperature over Iran. The ensemble employs three limited area models (WRF, MM5 and HRM), with WRF used with five different configurations. Initial and boundary conditions for MM5 and WRF are obtained from the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) and for HRM the initial and boundary conditions come from analysis of Global Model Europe (GME) of the German Weather Service. The resulting ensemble of seven members was run for a period of 6 months (from December 2008 to May 2009) over Iran. The 48-h raw ensemble outputs were calibrated using BMA technique for 120 days using a 40 days training sample of forecasts and relative verification data. The calibrated probabilistic forecasts were assessed using rank histogram and attribute diagrams. Results showed that application of BMA improved the reliability of the raw ensemble. Using the weighted ensemble mean forecast as a deterministic forecast it was found that the deterministic-style BMA forecasts performed usually better than the best member's deterministic forecast. (orig.)

  5. Using Bayesian Model Averaging (BMA to calibrate probabilistic surface temperature forecasts over Iran

    Directory of Open Access Journals (Sweden)

    I. Soltanzadeh

    2011-07-01

    Full Text Available Using Bayesian Model Averaging (BMA, an attempt was made to obtain calibrated probabilistic numerical forecasts of 2-m temperature over Iran. The ensemble employs three limited area models (WRF, MM5 and HRM, with WRF used with five different configurations. Initial and boundary conditions for MM5 and WRF are obtained from the National Centers for Environmental Prediction (NCEP Global Forecast System (GFS and for HRM the initial and boundary conditions come from analysis of Global Model Europe (GME of the German Weather Service. The resulting ensemble of seven members was run for a period of 6 months (from December 2008 to May 2009 over Iran. The 48-h raw ensemble outputs were calibrated using BMA technique for 120 days using a 40 days training sample of forecasts and relative verification data. The calibrated probabilistic forecasts were assessed using rank histogram and attribute diagrams. Results showed that application of BMA improved the reliability of the raw ensemble. Using the weighted ensemble mean forecast as a deterministic forecast it was found that the deterministic-style BMA forecasts performed usually better than the best member's deterministic forecast.

  6. Calibration of a Species-Specific Spectral Vegetation Index for Leaf Area Index (LAI Monitoring: Example with MODIS Reflectance Time-Series on Eucalyptus Plantations

    Directory of Open Access Journals (Sweden)

    Guerric le Maire

    2012-11-01

    Full Text Available The leaf area index (LAI is a key characteristic of forest ecosystems. Estimations of LAI from satellite images generally rely on spectral vegetation indices (SVIs or radiative transfer model (RTM inversions. We have developed a new and precise method suitable for practical application, consisting of building a species-specific SVI that is best-suited to both sensor and vegetation characteristics. Such an SVI requires calibration on a large number of representative vegetation conditions. We developed a two-step approach: (1 estimation of LAI on a subset of satellite data through RTM inversion; and (2 the calibration of a vegetation index on these estimated LAI. We applied this methodology to Eucalyptus plantations which have highly variable LAI in time and space. Previous results showed that an RTM inversion of Moderate Resolution Imaging Spectroradiometer (MODIS near-infrared and red reflectance allowed good retrieval performance (R2 = 0.80, RMSE = 0.41, but was computationally difficult. Here, the RTM results were used to calibrate a dedicated vegetation index (called “EucVI” which gave similar LAI retrieval results but in a simpler way. The R2 of the regression between measured and EucVI-simulated LAI values on a validation dataset was 0.68, and the RMSE was 0.49. The additional use of stand age and day of year in the SVI equation slightly increased the performance of the index (R2 = 0.77 and RMSE = 0.41. This simple index opens the way to an easily applicable retrieval of Eucalyptus LAI from MODIS data, which could be used in an operational way.

  7. Studies of float glass surfaces by neutron and x-ray reflection

    International Nuclear Information System (INIS)

    Dalgliesh, R.

    2001-09-01

    The surface of glass and glass coatings have been studied using x-ray and neutron scattering techniques. In particular, the effect of aqueous solutions and humid atmospheres on both the fire polished and the tin rich side of float glass have been investigated using neutron and x-ray reflection. Isotopic substitution has enabled the number density of water molecules within the float glass surface to be monitored with respect to immersion time, temperature and impurity content. A thin gel-like water-rich layer of thickness ∼30A is observed at the surface accompanied by a more deeply penetrating layer which increases in depth with time reaching ∼500A after 6 months. The rate of water ingression is higher than predicted from previous work carried out at elevated temperatures. Small decreases in the depth of penetration have been observed for glass containing alumina and tin. Water penetration into thin films made by a sol-gel process have also been studied. The hydrophobicity of these films had been varied by the addition of fluoroalkylsilane. Neutron and X-ray reflection revealed that water entered the highly hydrophobic films readily from the vapour phase. This suggests a method of film destabilisation by which water enters the film and freezes, causing the film to crack. Changes in fluoroalkylsilane content and annealing have little effect on the penetration of water into the coatings. Etched float glass surfaces have been used as a system for testing the applicability of current off-specular scattering models. A rich surface structure has been found which results in reflection effects that cannot be explained by these models. Model systems have also been developed in an attempt to combine x-ray fluorescence techniques with reflectivity. (author)

  8. Bi-directional Reflectance of Icy Surface Analogs: A Dual Approach

    Science.gov (United States)

    Quinones, Juan Manuel; Vides, Christina; Nelson, Robert M.; Boryta, Mark; Mannat, Ken s.

    2018-01-01

    Bi-directional reflectance measurements of analogs for planetary regolith have provided insight into the surface properties of planetary satellites and small bodies. Because Aluminum Oxide (Al2O3) and water ice share a similar hexagonal crystalline structure, the former has been used in laboratory experiments to simulate the regolith of both icy and dusty planetary bodies. By measuring various sizes of well sorted size fractions of Al2O3, the reflectance phase curve and porosity of a planetary regolith can be determined. We have designed an experiment to test the laboratory measurements produced by Nelson et al. (2000). Additionally, we made reflectance measurements for other alkali-halide compounds that could be used for applications beyond astronomy and planetary science.In order to provide an independent check on the Nelson et al. data, we designed an instrument with a different configuration. While both instruments take bidirectional reflectance measurements, our instrument, the Rigid Photometric Goniometer (RPG), is fixed at a phase angle of 5° and detects the scattered light with a photomultiplier tube (PMT). The PMT current is then measured with an electrometer. Following the example of Nelson et al., we measured the bidirectional reflectance of Al2O3 particulate size fractions between 0.1reflectance measurements for NaCl and KCl of sizes from 20reflectance applications beyond astronomy and planetary science. The objective of the experiment was to determine the particle size that provided optimal, or maximum, reflectance for each compound. Our conclusions bring confirmation and clarity to photometric sciences.

  9. Biomimetic approaches to create anti-reflection glass surfaces for solar cells using self-organizing techniques

    Energy Technology Data Exchange (ETDEWEB)

    Achtelik, J.; Sievers, W. [University of Paderborn, Department of Physics, 33098 Paderborn (Germany); Center of Optoelectronics and Photonics Paderborn CeOPP, 33098 Paderborn (Germany); Lindner, J.K.N., E-mail: lindner@physik.uni-paderborn.de [University of Paderborn, Department of Physics, 33098 Paderborn (Germany); Center of Optoelectronics and Photonics Paderborn CeOPP, 33098 Paderborn (Germany)

    2013-05-15

    Highlights: ► Nanostructured glass surfaces with theoretically near-to-zero reflectivity in the UVNIR region. ► Simple fabrication process using self-organization during reactive ion etching proposed. ► Prediction of optical reflectivity from AFM measured surface morphology. -- Abstract: Aiming to diminish the reflection losses of glass covered light harvesting devices, the optical reflectivity of nanostructured glass surfaces is studied theoretically and experimentally. The work is inspired by the nanoscale roughness of insect eyes, which is tried to be replicated on a technical glass surface. To this end, the reflectivity of glass surfaces with topographies represented by linear, parabolic and Fermi-shaped glass/air fill factor profiles is calculated for normal incidence. It is shown that using the latter ones, an almost complete suppression of reflections can be achieved. A simple, self-organization technique to create such Fermi-shaped filling factor profiles in glass experimentally is also presented.

  10. Calibration of the Chemcatcher passive sampler for monitoring selected polar and semi-polar pesticides in surface water

    International Nuclear Information System (INIS)

    Gunold, Roman; Schaefer, Ralf Bernhard; Paschke, Albrecht; Schueuermann, Gerrit; Liess, Matthias

    2008-01-01

    Passive sampling is a powerful method for continuous pollution monitoring, but calibration experiments are still needed to generate sampling rates in order to estimate water concentrations for polar compounds. We calibrated the Chemcatcher device with an uncovered SDB-XC Empore disk as receiving phase for 12 polar and semi-polar pesticides in aquatic environments in flow-through tank experiments at two water flow velocities (0.135 m/s and 0.4 m/s). In the 14-day period of exposure the uptake of test substances in the sampler remained linear, and all derived sampling rates R s were in the range of 0.1 to 0.5 L/day. By additionally monitoring the release of two preloaded polar pesticides from the SDB-XC disks over time, very high variation in release kinetics was found, which calls into question the applicability of performance reference compounds. Our study expands the applicability of the Chemcatcher for monitoring trace concentrations of pesticides with frequent occurrence in water. - We calibrated the Chemcatcher passive sampler for current-use polar pesticides in surface waters, allowing its application in future monitoring studies

  11. Transmission/reflection behaviors of surface plasmons at an interface between two plasmonic systems

    Science.gov (United States)

    Guan, Fuxin; Sun, Shulin; Ma, Shaojie; Fang, Zhening; Zhu, Baocheng; Li, Xin; He, Qiong; Xiao, Shiyi; Zhou, Lei

    2018-03-01

    Although surface plasmon polaritons (SPPs) have been intensively studied in past years, the transmission/reflection properties of SPPs at an interface between two plasmonic media are still not fully understood. In this article, we employ a mode expansion method (MEM) to systematically study such a problem based on a model system jointing two superlattices, each consisting of a periodic stacking of dielectric and plasmonic slabs with different material properties. Such a generic model can represent two widely used plasmonic structures (i.e. interfaces between two single dielectric/metal systems or between two metal–insulator–metal waveguides) under certain conditions. Our MEM calculations, in excellent agreement with full-wave simulations, uncover the rich physics behind the SPP reflections at generic plasmonic interfaces. In particular, we successfully derive from the MEM several analytical formulas that can quantitatively describe the SPP reflections at different plasmonic interfaces, and show that our formulas exhibit wider applicable regions than previously proposed empirical ones.

  12. Antarctic Surface Reflectivity Measurements from the ANITA-3 and HiCal-1 Experiments

    Science.gov (United States)

    Gorham, P. W.; Allison, P.; Banerjee, O.; Beatty, J. J.; Belov, K.; Besson, D. Z.; Binns, W. R.; Bugaev, V.; Cao, P.; Chen, C.; Chen, P.; Clem, J. M.; Connolly, A.; Dailey, B.; Dasgupta, P.; Deaconu, C.; Cremonesi, L.; Dowkontt, P. F.; Fox, B. D.; Gordon, J.; Hill, B.; Hupe, R.; Israel, M. H.; Jain, P.; Kowalski, J.; Lam, J.; Learned, J. G.; Liewer, K. M.; Liu, T. C.; Matsuno, S.; Miki, C.; Mottram, M.; Mulrey, K.; Nam, J.; Nichol, R. J.; Novikov, A.; Oberla, E.; Prohira, S.; Rauch, B. F.; Romero-Wolf, A.; Rotter, B.; Ratzlaff, K.; Russell, J.; Saltzberg, D.; Seckel, D.; Schoorlemmer, H.; Stafford, S.; Stockham, J.; Stockham, M.; Strutt, B.; Tatem, K.; Varner, G. S.; Vieregg, A. G.; Wissel, S. A.; Wu, F.; Young, R.

    The primary science goal of the NASA-sponsored ANITA project is measurement of ultra-high energy neutrinos and cosmic rays, observed via radio-frequency signals resulting from a neutrino or cosmic ray interaction with terrestrial matter (e.g. atmospheric or ice molecules). Accurate inference of the energies of these cosmic rays requires understanding the transmission/reflection of radio wave signals across the ice-air boundary. Satellite-based measurements of Antarctic surface reflectivity, using a co-located transmitter and receiver, have been performed more-or-less continuously for the last few decades. Our comparison of four different reflectivity surveys, at frequencies ranging from 2 to 45GHz and at near-normal incidence, yield generally consistent maps of high versus low reflectivity, as a function of location, across Antarctica. Using the Sun as an RF source, and the ANITA-3 balloon borne radio-frequency antenna array as the RF receiver, we have also measured the surface reflectivity over the interval 200-1000MHz, at elevation angles of 12-30∘. Consistent with our previous measurement using ANITA-2, we find good agreement, within systematic errors (dominated by antenna beam width uncertainties) and across Antarctica, with the expected reflectivity as prescribed by the Fresnel equations. To probe low incidence angles, inaccessible to the Antarctic Solar technique and not probed by previous satellite surveys, a novel experimental approach (“HiCal-1”) was devised. Unlike previous measurements, HiCal-ANITA constitute a bi-static transmitter-receiver pair separated by hundreds of kilometers. Data taken with HiCal, between 200 and 600MHz shows a significant departure from the Fresnel equations, constant with frequency over that band, with the deficit increasing with obliquity of incidence, which we attribute to the combined effects of possible surface roughness, surface grain effects, radar clutter and/or shadowing of the reflection zone due to Earth

  13. Measuring and modeling near-surface reflected and emitted radiation fluxes at the FIFE site

    Science.gov (United States)

    Blad, Blaine L.; Walter-Shea, Elizabeth A.; Starks, Patrick J.; Vining, Roel C.; Hays, Cynthia J.; Mesarch, Mark A.

    1990-01-01

    Information is presented pertaining to the measurement and estimation of reflected and emitted components of the radiation balance. Information is included about reflectance and transmittance of solar radiation from and through the leaves of some grass and forb prairie species, bidirectional reflectance from a prairie canopy is discussed and measured and estimated fluxes are described of incoming and outgoing longwave and shortwave radiation. Results of the study showed only very small differences in reflectances and transmittances for the adaxial and abaxial surfaces of grass species in the visible and infrared wavebands, but some differences in the infrared wavebands were noted for the forbs. Reflectance from the prairie canopy changed as a function of solar and view zenith angles in the solar principal plane with definite asymmetry about nadir. The surface temperature of prairie canopies was found to vary by as much as 5 C depending on view zenith and azimuth position and on the solar azimuth. Aerodynamic temperature calculated from measured sensible heat fluxes ranged from 0 to 3 C higher than nadir-viewed temperatures. Models were developed to estimate incoming and reflected shortwave radiation from data collected with a Barnes Modular Multiband Radiometer. Several algorithms for estimating incoming longwave radiation were evaluated and compared to actual measures of that parameter. Net radiation was calculated using the estimated components of the shortwave radiation streams, determined from the algorithms developed, and from the longwave radiation streams provided by the Brunt, modified Deacon, and the Stefan-Boltzmann models. Estimates of net radiation were compared to measured values and found to be within the measurement error of the net radiometers used in the study.

  14. Energy loss of MeV protons specularly reflected from metal surfaces

    International Nuclear Information System (INIS)

    Juaristi, J.I.; Garcia de Abajo, F.J.; Echenique, P.M.

    1996-01-01

    A parameter-free model is presented to study the energy loss of fast protons specularly reflected from metal surfaces. The contributions to the energy loss from excitation of valence-band electrons and ionization of localized target-atom electronic states are calculated separately. The former is calculated from the induced surface wake potential using linear response theory and the specular-reflection model, while the latter is calculated in the first Born approximation. The results obtained are in good agreement with available experimental data. However, the experimental qualitative trend of the energy loss as a function of the angle of incidence is obtained when the valence-band electron model is replaced by localized target atom electron states, though with a worse quantitative agreement. copyright 1996 The American Physical Society

  15. Surface plasmon resonance sensors based on uniform-waist tapered fibers in a reflective configuration

    Science.gov (United States)

    Esteban, Óscar; Díaz-Herrera, Natalia; Navarrete, María-Cruz; González-Cano, Agustín

    2006-10-01

    We present a configuration for surface plasmon resonance sensors based on uniform-waist tapered optical fibers and reflective elements. Once the fiber is tapered fulfilling the adiabatic criterion, a multilayer including a metallic medium is asymmetrically deposited on the uniform waist of the fiber. This feature provides the resonant excitation of multiple surface plasma waves. In addition, a mirror is produced at the fiber tip by a chemical Tollens reaction. In this way, the sensor operates in a reflective mode, more convenient for dip probes. When these sensors are spectrally interrogated, a high sensitivity of 10-4 refractive index units per nanometer is attained. These devices can be advantageously used for any kind of chemical sensing and biosensing.

  16. Glazed ceramic roof tiles: influence of surface features in the solar reflectance index

    International Nuclear Information System (INIS)

    Bortoli, Leitcia Silva de; Stapait, Camila Cristina; Marinoski, Deivis Luis; Fredel, Marcio Celso; Schabbach, Luciana M.

    2016-01-01

    In this study the influence of surface features of ceramic roof tiles in the solar reflectance index were evaluated. Two glazed ceramic roof tiles (type stoneware) with the same color (ivory) but with different appearance (matte and brilliant) were the focus of the analysis. The Solar Reflectance Index (SRI) of the roofs tiles were determined by the solar reflectance values (UV-VIS-NIR) and emittance, measured in laboratory. The samples showed SRI> 39 in accordance with LEED certification criteria (Leadership in Energy and Environmental Design), contributing to minimizing the Heat Island Effects. Although the matte roof tile shows a slightly higher SRI value (82) than the brilliant one (78), the results for the variables that composes the SRI value (reflectance and emittance) were very similar. Analysis of XRD, SEM and EDS performed on the surfaces of the two roofs indicated for the matte glaze the presence of microcrystals (with barium and zinc) that can contribute to the slightly highest value of SRI. The roughness (optical interferometer white light) and the brightness (brightness meter) of the samples were also measured. (author)

  17. Absorption and reflectivity of the lithium niobate surface masked with a graphene layer

    Directory of Open Access Journals (Sweden)

    O. Salas

    2017-01-01

    Full Text Available We performed simulations of the interaction of a graphene layer with the surface of lithium niobate utilizing density functional theory and molecular dynamics at 300K and atmospheric pressure. We found that the graphene layer is physisorbed on the lithium niobate surface with an adsorption energy of -0.8205 eV/(carbon-atom. Subsequently, the energy band structure, the optical absorption and reflectivity of the new system were calculated. We found important changes in these physical properties with respect to the corresponding ones of a graphene layer and of a lithium niobate crystal.

  18. Combined analysis of surface reflection imaging and vertical seismic profiling at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Daley, T.M.; Majer, E.L.; Karageorgi, E.

    1994-08-01

    This report presents results from surface and borehole seismic profiling performed by the Lawrence Berkeley Laboratory (LBL) on Yucca Mountain. This work was performed as part of the site characterization effort for the potential high-level nuclear waste repository. Their objective was to provide seismic imaging from the near surface (200 to 300 ft. depth) to the repository horizon and below, if possible. Among the issues addressed by this seismic imaging work are location and depth of fracturing and faulting, geologic identification of reflecting horizons, and spatial continuity of reflecting horizons. The authors believe their results are generally positive, with tome specific successes. This was the first attempt at this scale using modem seismic imaging techniques to determine geologic features on Yucca Mountain. The principle purpose of this report is to present the interpretation of the seismic reflection section in a geologic context. Three surface reflection profiles were acquired and processed as part of this study. Because of environmental concerns, all three lines were on preexisting roads. Line 1 crossed the mapped surface trace of the Ghost Dance fault and it was intended to study the dip and depth extent of the fault system. Line 2 was acquired along Drill Hole wash and was intended to help the ESF north ramp design activities. Line 3 was acquired along Yucca Crest and was designed to image geologic horizons which were thought to be less faulted along the ridge. Unfortunately, line 3 proved to have poor data quality, in part because of winds, poor field conditions and limited time. Their processing and interpretation efforts were focused on lines 1 and 2 and their associated VSP studies

  19. Fluctuations of noiselike signals reflected from a rough surface at the output of a correlation receiver

    Science.gov (United States)

    Gulin, E. P.

    2005-11-01

    The frequency and time averaging of the fluctuations that occur in the cross-correlation function of a radiated noiselike acoustic signal with the signal received after its reflection from a rough water surface is considered. The variance and temporal correlation function are calculated for the output effect of a correlation receiver for different ratios between the averaging time and the time correlation interval of fluctuations, the band width of the radiated signal, and the frequency correlation interval of the transfer function fluctuations.

  20. Observations of discrete energy loss effects in spectra of positrons reflected from solid surfaces

    International Nuclear Information System (INIS)

    Dale, J.M.; Hulett, L.D.; Pendyala, S.

    1980-01-01

    Surfaces of tungsten and silicon have been bombarded with monoenergetic beams of positrons and electrons. Spectra of reflected particles show energy loss tails with discrete peaks at kinetic energies about 15 eV lower than that of the elastic peaks. In the higher energy loss range for tungsten, positron spectra show fine structure that is not apparent in the electron spectra. This suggests that the positrons are losing energy through mechanisms different from that of the electrons

  1. Decadal changes of surface elevation over permafrost area estimated using reflected GPS signals

    Science.gov (United States)

    Liu, Lin; Larson, Kristine M.

    2018-02-01

    Conventional benchmark-based survey and Global Positioning System (GPS) have been used to measure surface elevation changes over permafrost areas, usually once or a few times a year. Here we use reflected GPS signals to measure temporal changes of ground surface elevation due to dynamics of the active layer and near-surface permafrost. Applying the GPS interferometric reflectometry technique to the multipath signal-to-noise ratio data collected by a continuously operating GPS receiver mounted deep in permafrost in Barrow, Alaska, we can retrieve the vertical distance between the antenna and reflecting surface. Using this unique kind of observables, we obtain daily changes of surface elevation during July and August from 2004 to 2015. Our results show distinct temporal variations at three timescales: regular thaw settlement within each summer, strong interannual variability that is characterized by a sub-decadal subsidence trend followed by a brief uplift trend, and a secular subsidence trend of 0.26 ± 0.02 cm year-1 during 2004 and 2015. This method provides a new way to fully utilize data from continuously operating GPS sites in cold regions for studying dynamics of the frozen ground consistently and sustainably over a long time.

  2. A Study on Infrared Emissivity Measurement of Material Surface by Reflection Method

    International Nuclear Information System (INIS)

    Kang, Byung Chul; Kim, Sang Myoung; Choi, Joung Yoon; Kim, Gun Ok

    2010-01-01

    Infrared emissivity is one of the most important factors for the temperature measurement by infrared thermography. Although the infrared emissivity of an object can be measured from the ratio of blackbody and the object, at room temperature it is practically difficult to measure the value due to the background effects. Hence, quantitative reflectance of bare steel plate and the surface of coating was measured by FT-IR spectroscopy and emissivity was calculated from this. The emissivity of polished bare steel surface was from 0.06 to 0.10 and the value for the unpolished bare steel can not be achieved because optical characteristics changes of surface roughness induces erroneous results. Emissivity of transparent paint coated steel was from 0.50 to 0.84. Depends on the IR absorption regions, which is a characteristic value of the coating, emissivity changes. This study suggests surface condition of material, thickness, roughness etcetra are important factor for IR optical characteristics. Emissivity measurement by reflection method is useful technique to be applied for metal and it with coating applied on the surface. The range of experimental errors of temperature can be narrowed by the application of infrared thermography from the measured thermal emissivity

  3. A rendering method of background reflections on a specular surface for CGH

    International Nuclear Information System (INIS)

    Ichikawa, T; Sakamoto, Y

    2013-01-01

    Computer-generated holograms (CGHs) are remarked as ideal three-dimensional displays. There are a lot of problems have to be overcome, and we focused on the rendering techniques to reconstruct realistic images. In particular, there is almost no calculation method that correctly expresses depth information. Reflected images are necessary to express complex realistic scenes. In this paper, we introduce a calculation method that generates reconstructed images with background reflections. Proposed method calculates intersections between virtual objects and rays by the ray tracing method. Then intersections are assumed as a point light source group, and light waves on a hologram plane are calculated. In the ray tracing process, when a ray hits the specular object, a ray is additionally casted to the specular direction from the intersection. If the ray hits other diffuse objects or background, the length of light path from a viewpoint to the diffuse object is calculated. By calculating light waves from a point light source on the diffuse surface distant from the light path, reflected images are expressed in the CGH. To express the quality of materials, we adopted the Cook-Torrance reflection model. In the experiment, we conducted the computer simulation to confirm that the depth of reflected images is correctly calculated. And results of optical reconstructions show that our proposed method is able to make CGHs of various qualities of material.

  4. IRAS surface brightness maps of visible reflection nebulae: evidence for non-equilibrium infrared emission

    International Nuclear Information System (INIS)

    Castelaz, M.W.; Werner, M.W.; Sellgren, K.

    1986-01-01

    Surface brightness maps at 12, 25, 60, and 100 microns of 16 visible reflection nebulae were extracted from the Infrared Astronomy Satellite (IRAS) database. The maps were produced by coadding IRAS survey scans over areas centered on the illuminating stars, and have spatial resolutions of 0.9' x 4' at 12 and 25 microns, 1.8' x 4.5' at 60 microns, and 3.6' x 5' at 100 microns. Extended emission in the four IRAS bandpasses was detected in fourteen of the reflection nebulae. The IRAS data were used to measure the flux of the infrared emission associated with each source. The energy distributions show that the 12 micron flux is greater than the 25 micron flux in 11 of the nebulae, and the peak flux occurs in the 60 or 100 micron bandpass in all 16 nebular. The 60 and 100 micron flux can be approximated by blackbodies with temperatures between 30 and 50 K, consistent with temperatures expected from extrapolation of greybody fits to the 60 and 100 micron data. The excess 12 and 25 micron emission is attributed to a nonequilibrium process such as emission from thermal fluctuations of very small grains excited by single ultraviolet photons, or emission from polycyclic aromatic hydrocarbons (PAHs) excited by ultraviolet radiation. The common features of the energy distributions of the 16 reflection nebulae, also seen in the reflection nebulae associated with the Pleiades, suggest that PAHs or very small grains may be found in most reflection nebulae

  5. Gain-Enhanced On-Chip Antenna Utilizing Artificial Magnetic Conductor Reflecting Surface at 94 GHz

    KAUST Repository

    Nafe, Mahmoud

    2015-08-04

    Nowadays, there is a growing demand for high frequency-bandwidth mm-wave (30-300 GHz) electronic wireless transceiver systems to support applications such as high data-rate wireless communication and high resolution imaging. Such mm-wave systems are becoming more feasible due to the extreme transistor downscaling in silicon-based integrated circuits, which enabled densely-integrated high-speed elec- tronics operating up to more than 100 GHz with low fabrication cost. To further enhance system integrability, it is required to implement all wireless system compo- nents on the chip. Presently, the last major barrier to true System-on-Chip (SoC) realization is the antenna implementation on the silicon chip. Although at mm-wave frequencies the antenna size becomes small enough to fit on chip, the antenna performance is greatly deteriorated due the high conductivity and high relative permittivity of the silicon substrate. The negative e↵ects of the silicon substrate could be avoided by using a metallic reflecting surface on top of silicon, which e↵ectively isolates the antenna from the silicon. However, this approach has the shortcoming of having to implement the antenna on the usually very thin silicon oxide layer of a typical CMOS fabrication process (10’s of μm). This forces the antenna to be in a very close proximity (less than one hundredth of a wavelength) to the reflecting surface. In this regime, the use of conventional metallic reflecting surface for silicon shielding has severe e↵ects on the antenna performance as it tends to reduce the antenna radiation resistance resulting in most of the energy being absorbed rather than radiated. In this work, the use of specially patterned reflecting surfaces for improving on- chip antenna performance is investigated. By using a periodic metallic surface on top of a grounded substrate, the structure can mimic the behavior of a perfect mag- netic conductor, hence called Artificial Magnetic Conductor (AMC) surface

  6. Surface Compositional Units on Mercury from Spectral Reflectance at Ultraviolet to Near-infrared Wavelengths

    Science.gov (United States)

    Izenberg, N. R.; Holsclaw, G. M.; Domingue, D. L.; McClintock, W. E.; Klima, R. L.; Blewett, D. T.; Helbert, J.; Head, J. W.; Sprague, A. L.; Vilas, F.; Solomon, S. C.

    2012-12-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has been acquiring reflectance spectra of Mercury's surface for over 16 months. The Visible and Infrared Spectrograph (VIRS) component of MASCS has accumulated a global data set of more than 2 million spectra over the wavelength range 300-1450 nm. We have derived a set of VIRS spectral units (VSUs) from the following spectral parameters: visible brightness (R575: reflectance at 575 nm); visible/near-infrared reflectance ratio (VISr: reflectance at 415 nm to that at 750 nm); and ultraviolet reflectance ratio (UVr: reflectance at 310 nm to that at 390 nm). Five broad, slightly overlapping VSUs may be distinguished from these parameters. "Average VSU" areas have spectral parameters close to mean global values. "Dark blue VSU" areas have spectra with low R575 and high UVr. "Red VSU" areas have spectra with low UVr and higher VISr and R575 than average. "Intermediate VSU" areas have spectra with higher VISr than VSU red, generally higher R575, and a wide range of UVr. "Bright VSU" areas have high R575 and VISr and intermediate UVr. Several units defined by morphological or multispectral criteria correspond to specific VSUs, including low-reflectance material (dark blue VSU), pyroclastic deposits (red VSU), and hollows (intermediate VSU), but these VSUs generally include other types of areas as well. VSU definitions are complementary to those obtained by unsupervised clustering analysis. The global distribution of VIRS spectral units provides new information on Mercury's geological evolution. Much of Mercury's northern volcanic plains show spectral properties ranging from those of average VSU to those of red VSU, as does a large region in the southern hemisphere centered near 50°S, 245°E. Dark blue VSU material is widely distributed, with concentrations south of the northern plains, around the Rembrandt and

  7. Measurements of long-range interactions between protein-functionalized surfaces by total internal reflection microscopy.

    Science.gov (United States)

    Wang, Zhaohui; Gong, Xiangjun; Ngai, To

    2015-03-17

    Understanding the interaction between protein-functionalized surfaces is an important subject in a variety of protein-related processes, ranging from coatings for biomedical implants to targeted drug carriers and biosensors. In this work, utilizing a total internal reflection microscope (TIRM), we have directly measured the interactions between micron-sized particles decorated with three types of common proteins concanavalin A (ConA), bovine serum albumin (BSA), lysozyme (LYZ), and glass surface coated with soy proteins (SP). Our results show that the protein adsorption greatly affects the charge property of the surfaces, and the interactions between those protein-functionalized surfaces depend on solution pH values. At pH 7.5-10.0, all these three protein-functionalized particles are highly negatively charged, and they move freely above the negatively charged SP-functionalized surface. The net interaction between protein-functionalized surfaces captured by TIRM was found as a long-range, nonspecific double-layer repulsion. When pH was decreased to 5.0, both protein-functionalized surfaces became neutral and double-layer repulsion was greatly reduced, resulting in adhesion of all three protein-functionalized particles to the SP-functionalized surface due to the hydrophobic attraction. The situation is very different at pH = 4.0: BSA-decorated particles, which are highly charged, can move freely above the SP-functionalized surfaces, while ConA- and LYZ-decorated particles can only move restrictively in a limited range. Our results quantify these nonspecific kT-scale interactions between protein-functionalized surfaces, which will enable the design of surfaces for use in biomedical applications and study of biomolecular interactions.

  8. Experimental calibration and validation of sewer/surface flow exchange equations in steady and unsteady flow conditions

    Science.gov (United States)

    Rubinato, Matteo; Martins, Ricardo; Kesserwani, Georges; Leandro, Jorge; Djordjević, Slobodan; Shucksmith, James

    2017-09-01

    The linkage between sewer pipe flow and floodplain flow is recognised to induce an important source of uncertainty within two-dimensional (2D) urban flood models. This uncertainty is often attributed to the use of empirical hydraulic formulae (the one-dimensional (1D) weir and orifice steady flow equations) to achieve data-connectivity at the linking interface, which require the determination of discharge coefficients. Because of the paucity of high resolution localised data for this type of flows, the current understanding and quantification of a suitable range for those discharge coefficients is somewhat lacking. To fulfil this gap, this work presents the results acquired from an instrumented physical model designed to study the interaction between a pipe network flow and a floodplain flow. The full range of sewer-to-surface and surface-to-sewer flow conditions at the exchange zone are experimentally analysed in both steady and unsteady flow regimes. Steady state measured discharges are first analysed considering the relationship between the energy heads from the sewer flow and the floodplain flow; these results show that existing weir and orifice formulae are valid for describing the flow exchange for the present physical model, and yield new calibrated discharge coefficients for each of the flow conditions. The measured exchange discharges are also integrated (as a source term) within a 2D numerical flood model (a finite volume solver to the 2D Shallow Water Equations (SWE)), which is shown to reproduce the observed coefficients. This calibrated numerical model is then used to simulate a series of unsteady flow tests reproduced within the experimental facility. Results show that the numerical model overestimated the values of mean surcharge flow rate. This suggests the occurrence of additional head losses in unsteady conditions which are not currently accounted for within flood models calibrated in steady flow conditions.

  9. NPP/VIIRS Surface Reflectance Daily L2G Global 1km and 500m SIN Grid NRT

    Data.gov (United States)

    National Aeronautics and Space Administration — The VNP09GA_NRT is a Near Real Time (NRT) S-NPP/VIIRS 500m and 1km Daily Level 2G Surface Reflectance product. The NPP/ VIIRS surface reflectance products are...

  10. Incisor inclination determined by the light reflection zone on the tooth's surface.

    Science.gov (United States)

    Brezniak, Naphtali; Turgeman, Ronit; Redlich, Meir

    2010-01-01

    Maxillary incisors are the most prominent teeth, and their inclination plays an important role in esthetics. In orthodontics, the inclination of central incisors is usually determined by cephalometric analysis. This publication suggests an adjunctive clinical measure to determine this inclination. The objective of the study was to examine the correlation between the inclinations of maxillary incisors measured on a cephalometric lateral headfilm and the light reflection zone appearing on the buccal surface of the teeth on anterior intraoral photographs. Maxillary incisor inclination, divided into three levels-proclination, normal inclination, and retroclination-of 65 patients was determined by means of cephalometric analysis, using three angular measurements (maxillary incisor to sella-nasion, maxillary incisor to Frankfort horizontal, and maxillary incisor to nasion-point A). The anterior intraoral photographs of the 65 patients were divided into 3 groups according to the reflection zone on the maxillary central incisors as determined from the photographs: incisal, middle, and gingival. The correlation and agreement between the two parameters were evaluated by chi-square and kappa statistics. The light reflection zone on the tooth surface as it appears on intraoral photographs-incisal, middle, or gingival-correlated with statistical significance to the angular inclination of the teeth-proclination, normal inclination, and retroclination, respectively-as determined by means of cephalometric analysis (P light reflection zone viewed on the buccal surface of intraoral photographs. This method might be used as a new screening tool and further as an additional clinical tool for assessing treatment plans in orthodontics and other fields of dentistry.

  11. Determining surface coverage of ultra-thin gold films from X-ray reflectivity measurements

    International Nuclear Information System (INIS)

    Kossoy, A.; Simakov, D.; Olafsson, S.; Leosson, K.

    2013-01-01

    The paper describes usage of X-ray reflectivity for characterization of surface coverage (i.e. film continuity) of ultra-thin gold films which are widely studied for optical, plasmonic and electronic applications. The demonstrated method is very sensitive and can be applied for layers below 1 nm. It has several advantages over other techniques which are often employed in characterization of ultra-thin metal films, such as optical absorption, Atomic Force Microscopy, Transmission Electron Microscopy or Scanning Electron Microscopy. In contrast to those techniques our method does not require specialized sample preparation and measurement process is insensitive to electrostatic charge and/or presence of surface absorbed water. We validate our results with image processing of Scanning Electron Microscopy images. To ensure precise quantitative analysis of the images we developed a generic local thresholding algorithm which allowed us to treat series of images with various values of surface coverage with similar image processing parameters. - Highlights: • Surface coverage/continuity of ultra-thin Au films (up to 7 nm) was determined. • Results from X-ray reflectivity were verified by scanning electron microscopy. • We developed local thresholding algorithm to treat non-homogeneous image contrast

  12. Surface reflectance drives nest box temperature profiles and thermal suitability for target wildlife.

    Directory of Open Access Journals (Sweden)

    Stephen R Griffiths

    Full Text Available Thermal properties of tree hollows play a major role in survival and reproduction of hollow-dependent fauna. Artificial hollows (nest boxes are increasingly being used to supplement the loss of natural hollows; however, the factors that drive nest box thermal profiles have received surprisingly little attention. We investigated how differences in surface reflectance influenced temperature profiles of nest boxes painted three different colors (dark-green, light-green, and white: total solar reflectance 5.9%, 64.4%, and 90.3% respectively using boxes designed for three groups of mammals: insectivorous bats, marsupial gliders and brushtail possums. Across the three different box designs, dark-green (low reflectance boxes experienced the highest average and maximum daytime temperatures, had the greatest magnitude of variation in daytime temperatures within the box, and were consistently substantially warmer than light-green boxes (medium reflectance, white boxes (high reflectance, and ambient air temperatures. Results from biophysical model simulations demonstrated that variation in diurnal temperature profiles generated by painting boxes either high or low reflectance colors could have significant ecophysiological consequences for animals occupying boxes, with animals in dark-green boxes at high risk of acute heat-stress and dehydration during extreme heat events. Conversely in cold weather, our modelling indicated that there are higher cumulative energy costs for mammals, particularly smaller animals, occupying light-green boxes. Given their widespread use as a conservation tool, we suggest that before boxes are installed, consideration should be given to the effect of color on nest box temperature profiles, and the resultant thermal suitability of boxes for wildlife, particularly during extremes in weather. Managers of nest box programs should consider using several different colors and installing boxes across a range of both orientations and

  13. [The research of the relationship between snow properties and the bidirectional polarized reflectance from snow surface].

    Science.gov (United States)

    Sun, Zhong-Qiu; Wu, Zheng-Fang; Zhao, Yun-Sheng

    2014-10-01

    In the context of remote sensing, the reflectance of snow is a key factor for accurate inversion for snow properties, such as snow grain size, albedo, because of it is influenced by the change of snow properties. The polarized reflectance is a general phenomenon during the reflected progress in natural incident light In this paper, based on the correct measurements for the multiple-angle reflected property of snow field in visible and near infrared wavelength (from 350 to 2,500 nm), the influence of snow grain size and wet snow on the bidirectional polarized property of snow was measured and analyzed. Combining the results measured in the field and previous conclusions confirms that the relation between polarization and snow grain size is obvious in infrared wavelength (at about 1,500 nm), which means the degree of polarization increasing with an increase of snow grain size in the forward scattering direction, it is because the strong absorption of ice near 1,500 nm leads to the single scattering light contributes to the reflection information obtained by the sensor; in other word, the larger grain size, the more absorption accompanying the larger polarization in forward scattering direction; we can illustrate that the change from dry snow to wet snow also influences the polarization property of snow, because of the water on the surface of snow particle adheres the adjacent particles, that means the wet snow grain size is larger than the dry snow grain size. Therefore, combining the multiple-angle polarization with reflectance will provide solid method and theoretical basis for inversion of snow properties.

  14. Surface reflectance drives nest box temperature profiles and thermal suitability for target wildlife.

    Science.gov (United States)

    Griffiths, Stephen R; Rowland, Jessica A; Briscoe, Natalie J; Lentini, Pia E; Handasyde, Kathrine A; Lumsden, Linda F; Robert, Kylie A

    2017-01-01

    Thermal properties of tree hollows play a major role in survival and reproduction of hollow-dependent fauna. Artificial hollows (nest boxes) are increasingly being used to supplement the loss of natural hollows; however, the factors that drive nest box thermal profiles have received surprisingly little attention. We investigated how differences in surface reflectance influenced temperature profiles of nest boxes painted three different colors (dark-green, light-green, and white: total solar reflectance 5.9%, 64.4%, and 90.3% respectively) using boxes designed for three groups of mammals: insectivorous bats, marsupial gliders and brushtail possums. Across the three different box designs, dark-green (low reflectance) boxes experienced the highest average and maximum daytime temperatures, had the greatest magnitude of variation in daytime temperatures within the box, and were consistently substantially warmer than light-green boxes (medium reflectance), white boxes (high reflectance), and ambient air temperatures. Results from biophysical model simulations demonstrated that variation in diurnal temperature profiles generated by painting boxes either high or low reflectance colors could have significant ecophysiological consequences for animals occupying boxes, with animals in dark-green boxes at high risk of acute heat-stress and dehydration during extreme heat events. Conversely in cold weather, our modelling indicated that there are higher cumulative energy costs for mammals, particularly smaller animals, occupying light-green boxes. Given their widespread use as a conservation tool, we suggest that before boxes are installed, consideration should be given to the effect of color on nest box temperature profiles, and the resultant thermal suitability of boxes for wildlife, particularly during extremes in weather. Managers of nest box programs should consider using several different colors and installing boxes across a range of both orientations and shade profiles (i

  15. Simulation calculations of physical sputtering and reflection coefficient of plasma-irradiated carbon surface

    International Nuclear Information System (INIS)

    Kawamura, T.; Ono, T.; Yamamura, Y.

    1994-08-01

    Physical sputtering yields from the carbon surface irradiated by the boundary plasma are obtained with the use of a Monte Carlo simulation code ACAT. The yields are calculated for many random initial energy and angle values of incident protons or deuterons with a Maxwellian velocity distribution, and then averaged. Here the temperature of the boundary plasma, the sheath potential and the angle δ between the magnetic field line and the surface normal are taken into account. A new fitting formula for an arrangement of the numerical data of sputtering yield is introduced, in which six fitting parameters are determined from the numerical results and listed. These results provide a way to estimate the erosion of carbon materials irradiated by boundary plasma. The particle reflection coefficients for deuterons and their neutrals from a carbon surface are also calculated by the same code and presented together with, for comparison, that for the case of monoenergetic normal incidence. (author)

  16. Automatic and improved radiometric correction of Landsat imagery using reference values from MODIS surface reflectance images

    Science.gov (United States)

    Pons, X.; Pesquer, L.; Cristóbal, J.; González-Guerrero, O.

    2014-12-01

    Radiometric correction is a prerequisite for generating high-quality scientific data, making it possible to discriminate between product artefacts and real changes in Earth processes as well as accurately produce land cover maps and detect changes. This work contributes to the automatic generation of surface reflectance products for Landsat satellite series. Surface reflectances are generated by a new approach developed from a previous simplified radiometric (atmospheric + topographic) correction model. The proposed model keeps the core of the old model (incidence angles and cast-shadows through a digital elevation model [DEM], Earth-Sun distance, etc.) and adds new characteristics to enhance and automatize ground reflectance retrieval. The new model includes the following new features: (1) A fitting model based on reference values from pseudoinvariant areas that have been automatically extracted from existing reflectance products (Terra MODIS MOD09GA) that were selected also automatically by applying quality criteria that include a geostatistical pattern model. This guarantees the consistency of the internal and external series, making it unnecessary to provide extra atmospheric data for the acquisition date and time, dark objects or dense vegetation. (2) A spatial model for atmospheric optical depth that uses detailed DEM and MODTRAN simulations. (3) It is designed so that large time-series of images can be processed automatically to produce consistent Landsat surface reflectance time-series. (4) The approach can handle most images, acquired now or in the past, regardless of the processing system, with the exception of those with extremely high cloud coverage. The new methodology has been successfully applied to a series of near 300 images of the same area including MSS, TM and ETM+ imagery as well as to different formats and processing systems (LPGS and NLAPS from the USGS; CEOS from ESA) for different degrees of cloud coverage (up to 60%) and SLC

  17. Antibody adsorption on the surface of water studied by neutron reflection.

    Science.gov (United States)

    Smith, Charles; Li, Zongyi; Holman, Robert; Pan, Fang; Campbell, Richard A; Campana, Mario; Li, Peixun; Webster, John R P; Bishop, Steven; Narwal, Rojaramani; Uddin, Shahid; van der Walle, Christopher F; Lu, Jian R

    2017-04-01

    Surface and interfacial adsorption of antibody molecules could cause structural unfolding and desorbed molecules could trigger solution aggregation, resulting in the compromise of physical stability. Although antibody adsorption is important and its relevance to many mechanistic processes has been proposed, few techniques can offer direct structural information about antibody adsorption under different conditions. The main aim of this study was to demonstrate the power of neutron reflection to unravel the amount and structural conformation of the adsorbed antibody layers at the air/water interface with and without surfactant, using a monoclonal antibody 'COE-3' as the model. By selecting isotopic contrasts from different ratios of H 2 O and D 2 O, the adsorbed amount, thickness and extent of the immersion of the antibody layer could be determined unambiguously. Upon mixing with the commonly-used non-ionic surfactant Polysorbate 80 (Tween 80), the surfactant in the mixed layer could be distinguished from antibody by using both hydrogenated and deuterated surfactants. Neutron reflection measurements from the co-adsorbed layers in null reflecting water revealed that, although the surfactant started to remove antibody from the surface at 1/100 critical micelle concentration (CMC) of the surfactant, complete removal was not achieved until above 1/10 CMC. The neutron study also revealed that antibody molecules retained their globular structure when either adsorbed by themselves or co-adsorbed with the surfactant under the conditions studied.

  18. The influence of surface reflectance anisotropy on estimation of soil properties

    Science.gov (United States)

    Bartholomeus, Harm; Roosjen, Peter; Clevers, Jan

    2014-05-01

    The spatial variation in soil properties is an important factor for agricultural management. Unmanned airborne vehicles (UAV's) equipped with a hyperspectral mapping system may provide these data, but anisotropic reflectance effects may have an influence on the derived soil properties. Besides influencing the reflectance, angular observations may deliver added information about soil properties. We investigated the anisotropic behavior of 59 soil samples with a large variation in soil composition, by measuring their reflectance (350-2500 nm) over 92 different angles using a robot-based laboratory goniometer system. The results show that the anisotropic behavior of the soils influences the measured reflectance significantly, which limits the accurate prediction of soil properties (OM and clay especially). However, prediction accuracies of OM increase when spectra are measured under specific angles. Prediction accuracies further increase when a combination of observation angles is being used. Apart from that, using UAV's the wavelength range is limited to about 1000 nm. In general, this will decrease the model performance, but our results show that this effect can largely be compensated by combining multiple observation angles. Altogether, we demonstrate that surface anisotropy influences the prediction of soil properties negatively. This effect can be reduced by combining spectra acquired under different angles. Moreover, predictions can be improved if combinations of different observation angles are used.

  19. Calibration and Validation of High Frequency Radar for Ocean Surface Current Mapping

    National Research Council Canada - National Science Library

    Kim, Kyung

    2004-01-01

    High Frequency (HF) radar backscatter instruments are being developed and tested in the marine science and defense science communities for their abilities to sense surface parameters remotely in the coastal ocean over large areas...

  20. Characterizing LEDAPS surface reflectance products by comparisons with AERONET, field spectrometer, and MODIS data

    Science.gov (United States)

    Maiersperger, Tom; Scaramuzza, Pat; Leigh, Larry; Shrestha, S.; Gallo, Kevin; Jenkerson, Calli B.; Dwyer, John L.

    2013-01-01

    This study provides a baseline quality check on provisional Landsat Surface Reflectance (SR) products as generated by the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center using Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS) software. Characterization of the Landsat SR products leveraged comparisons between aerosol optical thickness derived from LEDAPS and measured by Aerosol Robotic Network (AERONET), as well as reflectance correlations with field spectrometer and Moderate Resolution Imaging Spectroradiometer (MODIS) data. Results consistently indicated similarity between LEDAPS and alternative data products in longer wavelengths over vegetated areas with no adjacent water, while less reliable performance was observed in shorter wavelengths and sparsely vegetated areas. This study demonstrates the strengths and weaknesses of the atmospheric correction methodology used in LEDAPS, confirming its successful implementation to generate Landsat SR products.

  1. Reflection of X-rays from a rough surface at extremely small grazing angles.

    Science.gov (United States)

    Wen, Mingwu; Kozhevnikov, Igor V; Wang, Zhanshan

    2015-09-21

    Peculiarities of X-ray diffraction from a rough surface at an extremely small grazing angle of an incident beam are theoretically studied. The interrelation of four diffraction channels (coherent reflectance, coherent transmittance, diffuse scattering in vacuum, and scattering into the matter depth) is analyzed for different limiting cases (large and small correlation length of roughness and large and extremely small grazing angle of incident radiation). Both the Debye-Waller and the Nevot-Croce factors are demonstrated to describe improperly the features of X-ray diffraction at extremely small grazing angles. More appropriate simple analytic expressions for the specular reflectivity and total integrated scattering in vacuum are obtained instead. Transformation of one limiting diffraction regime into another one with variation in the correlation length of roughness is discussed.

  2. Monte Carlo simulation of light reflection from cosmetic powder particles near the human skin surface.

    Science.gov (United States)

    Okamoto, Takashi; Kumagawa, Tatsuya; Motoda, Masafumi; Igarashi, Takanori; Nakao, Keisuke

    2013-06-01

    The reflection and scattering properties of light incident on human skin covered with powder particles have been investigated. A three-layer skin structure with a pigmented area is modeled, and the propagation of light in the skin's layers and in a layer of particles near the skin's surface is simulated using the Monte Carlo method. Assuming that only single scattering of light occurs in the powder layer, the simulation results show that the reflection spectra of light from the skin change with the size of powder particles. The color difference between normal and discolored skin is found to decrease considerably when powder particles with a diameter of approximately 0.25 μm are present near the skin's surface. The effects of the medium surrounding the particles, and the influence of the distribution of particle size (polydispersity), are also examined. It is shown that a surrounding medium with a refractive index close to that of the skin substantially suppresses the extreme spectral changes caused by the powder particles covering the skin surface.

  3. Mathematical Modeling of Radiant Heat Transfer in Mirror Systems Considering Deep Reflecting Surface Defects

    Directory of Open Access Journals (Sweden)

    V. V. Leonov

    2014-01-01

    Full Text Available When designing large-sized mirror concentrating systems (MCS for high-temperature solar power plants, one must have at disposal reasonably reliable and economical methods and tools, making it possible to analyze its characteristics, to predict them depending on the operation conditions and accordingly to choose the most suitable system for the solution of particular task.Experimental determination of MCS characteristics requires complicated and expensive experimentation, having significant limitations on interpretation of the results, as well as limitations imposed due to the size of the structure. Therefore it is of particular interest to develop a mathematical model capable of estimating power characteristics of MCS considering the influence of operating conditions, design features, roughness and other surface defects.For efficient solution of the tasks the model must ensure simulation of solar radiant flux as well as simulation of geometrical and optical characteristics of reflection surface and their interaction. In this connection a statistical mathematical model of radiation heat exchange based on use of Monte Carlo methods and Finite Element Method was developed and realized in the software complex, making it possible to determine main characteristics of the MCS.In this paper the main attention is given to definition of MCS radiation characteristics with account for deep reflecting surface defects (cavities, craters. Deep cavities are not typical for MCS, but their occurrence is possible during operation as a result of erosion or any physical damage. For example, for space technology it is primarily micrometeorite erosion.

  4. Influence of coffee on reflectance and chemistry of resin composite protected by surface sealant.

    Science.gov (United States)

    Soares, Luís Eduardo Silva; Cesar, Ilene Cristine Rosia; Santos, Carla Gabriela Couto; De Cardoso, Ana Luiza Merigo Oliveira; Liporoni, Priscila Christiane Suzy; Munin, Egberto; Martin, Airton Abrahão

    2007-10-01

    To assess the influence of the light-curing unit type and whether or not it was worth using surface sealant protection on resin composite restorative materials stained by coffee. Another objective was to propose the monitoring of coffee staining by FT-Raman spectroscopy using carbon-hydrogen (C-H) bonds as reference to the composite matrix degradation. Sixty cylindrical specimens of resin composite were prepared and divided into six groups: HC (control)--cured with a halogen light; LC (control) cured with a LED; HF--cured with a halogen light + Fortify Plus; LF--cured with a LED + Fortify Plus; HP--cured with a halogen light + PermaSeal; LP--cured with a LED + PermaSeal. After storage for 24 hours at 37% and 100% of relative humidity, the top surface was protected, and the other surfaces isolated. Polishing with paper discs was performed after 24 hours of curing and prior to FT-Raman spectroscopy and reflectance measurements. All specimens were submitted to coffee staining for 14 days and evaluated by both systems. Results were statistically analyzed by ANOVA and Tukey tests. FT-Raman spectrum only showed significant changes in groups LC and LP (P< 0.05). Reflectance demonstrated that staining was present in all specimens protected by sealants. Sealant staining was larger in the HF (P < 0.001) group.

  5. High laser damage threshold surface relief micro-structures for anti-reflection applications

    Science.gov (United States)

    Hobbs, Douglas S.; MacLeod, Bruce D.

    2008-01-01

    Microstructures built into the surfaces of an optic or window, are an effective replacement for thin-film coatings in anti-reflection (AR) and narrow-band filter applications. AR microstructures exhibit particularly noteworthy performance where an average reflection loss of less than 0.2% over a four-octave range (400-1800nm) has been demonstrated, and a loss of less than 0.03% is routinely achieved for narrow-band applications. Because AR micro-textures provide a gradual change in the refractive index at a material boundary, it is expected that light can propagate through the boundary without material damage at energy levels that are much higher than that found with thin-film interference coatings. Recently, it was shown that the laser induced damage threshold (LIDT) of an inexpensive borosilicate glass window containing AR microstructures was nearly 57 J/cm2 at 1064nm (20ns pulse). This LIDT is two to three times greater than the damage threshold of single-layer sol-gel AR coatings on fused silica often reported in the literature. The development of surface relief AR textures for use in high-energy laser applications is presented. Data from scanning electron microscope (SEM) analysis, reflection measurements, and LIDT testing, is shown for high performance AR microstructures fabricated in fused silica, and borosilicate glass. Results of LIDT testing at wavelengths ranging from the near ultraviolet through the near infrared confirm the initial result that AR microstructures can operate at pulsed laser power levels at least two times higher than thin-film coatings. For near infrared applications such as laser weapons and fiber optic communications requiring high performance AR, LIDT levels for AR microstructures in fused silica are found to be at least five times greater than conventional multi-layer thin film coatings. An initial surface absorption test at 1064nm shows that AR microstructures may also exhibit improved lifetimes within continuous wave laser systems.

  6. A Conceptual Model of Surface Reflectance Estimation for Satellite Remote Sensing Images Using in situ Reference Data

    Directory of Open Access Journals (Sweden)

    Ke-Sheng Cheng

    2012-03-01

    Full Text Available For satellite remote sensing, radiances received at the sensor are not only affected by the atmosphere but also by the topographic properties of the terrain surface. As a result, atmospheric correction alone does not yield output images that truly reflect terrain surface properties, namely surface reflectance (bidirectional reflectance factor, BRF of objects on the earth surface. Following the concept of the radiometric control area (RCA-based path radiance estimation method, we herein propose a statistical approach for surface reflectance estimation utilizing DEM data and surface reflectance of selected radiometric control areas. An algorithm for identification of shaded samples and a shape factor model were also developed in this study. The proposed RCA-based surface reflectance estimation method is capable of achieving good reflectance estimates in a region where elevation varies from 0 to approximately 600 m above the mean sea level. However, further study is recommended in order to extend the application of the proposed method to areas with substantial terrain variation.

  7. Attenuated total reflectance spectroscopy of coumarin organosilane molecules adsorbed on a fused silica surface

    International Nuclear Information System (INIS)

    Bratescu, Maria Antoaneta; Saito, Nagahiro; Takai, Osamu

    2010-01-01

    Attenuated total reflectance (ATR) spectroscopy was used to investigate the adsorption of coumarin organosilane molecules onto a fused silica surface. The difference between the absorption spectra of the molecules on the surface and in solution was explained by the interaction of the adsorbed coumarin organosilane molecules with the hydroxyl groups on the fused silica surface. This interaction produces a perturbation of the π electron distribution and the electronic transitions of the coumarin chromophore of the organosilane molecules adsorbed on the surface. From the kinetics adsorption curves, the calculated enthalpy values of 74.8 ± 5.2 kJ mol -1 and free energy of -38.22 ± 0.70 kJ mol -1 at 23 deg. C indicates a chemisorption process. The high sensitivity of ATR spectroscopy allows the detection of a monolayer formed by a 10 nM concentration of coumarin organosilane molecules, which covers more than half of the maximum surface coverage at 60 deg. C.

  8. Multipitched Diffraction Gratings for Surface Plasmon Resonance-Enhanced Infrared Reflection Absorption Spectroscopy.

    Science.gov (United States)

    Petefish, Joseph W; Hillier, Andrew C

    2015-11-03

    We demonstrate the application of metal-coated diffraction gratings possessing multiple simultaneous pitch values for surface enhanced infrared absorption (SEIRA) spectroscopy. SEIRA increases the magnitude of vibrational signals in infrared measurements by one of several mechanisms, most frequently involving the enhanced electric field associated with surface plasmon resonance (SPR). While the majority of SEIRA applications to date have employed nanoparticle-based plasmonic systems, recent advances have shown how various metals and structures lead to similar signal enhancement. Recently, diffraction grating couplers have been demonstrated as a highly tunable platform for SEIRA. Indeed, gratings are an experimentally advantageous platform due to the inherently tunable nature of surface plasmon excitation at these surfaces since both the grating pitch and incident angle can be used to modify the spectral location of the plasmon resonance. In this work, we use laser interference lithography (LIL) to fabricate gratings possessing multiple pitch values by subjecting photoresist-coated glass slides to repetitive exposures at varying orientations. After metal coating, these gratings produced multiple, simultaneous plasmon peaks associated with the multipitched surface, as identified by infrared reflectance measurements. These plasmon peaks could then be coupled to vibrational modes in thin films to provide localized enhancement of infrared signals. We demonstrate the flexibility and tunability of this platform for signal enhancement. It is anticipated that, with further refinement, this approach might be used as a general platform for broadband enhancement of infrared spectroscopy.

  9. Classification of Clean and Dirty Pighouse Surfaces Based on Spectral Reflectance

    DEFF Research Database (Denmark)

    Blanke, Mogens; Braithwaite, Ian David; Zhang, Guo-Qiang

    2004-01-01

    Current pig house cleaning procedures are hazardous to the health of farm workers, and yet necessary if the spread of disease between batches of animals is to be satisfactorily controlled. Autonomous cleaning using robot technology offers salient benefits. This report addresses the feasibility...... of designing a vision based system to locate dirty areas and subsequently direct a cleaning robot to remove dirt. Novel results include the characterisation of the spectral reflectance of real surfaces and dirt in a pig house and the design of illumination to obtain discrimination of clean from dirty areas...

  10. Vertical-cavity surface-emitting laser vapor sensor using swelling polymer reflection modulation

    DEFF Research Database (Denmark)

    Ansbæk, Thor; Nielsen, Claus Højgård; Dohn, Søren

    2012-01-01

    Vapor detection using a low-refractive index polymer for reflection modulation of the top mirror in a vertical-cavity surface-emitting laser (VCSEL) is demonstrated. The VCSEL sensor concept presents a simple method to detect the response of a sensor polymer in the presence of volatile organic co...... compounds. We model the physics as a change in the top mirror loss caused by swelling of the polymer upon absorbing the target volatile organic compound. Further we show how acetone vapors at 82 000 ppm concentration can change the polymer coated VCSEL output power by 20 mu W....

  11. Development and applications of retro-reflective surfaces for ultrasound in LBE

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2015-07-01

    pulse or a complete absence of a reflection like a shadow. In that way, it suffices to align the sensor with the diaphragm instead of the fuel assembly which is much easier to achieve as the robotics on which the sensor is mounted move parallel with the diaphragm. The alignment requirement in the latter approach can be further relaxed by using a tiling of retro-reflectors on the lower surface of the diaphragm. In that way, alignment becomes less vital and the main source of acoustic energy loss - geometric spread of the beam - is almost completely removed, leaving only absorption losses. In this paper, we present the first results in developing a retro reflectance surface for ultrasound in LBE. We present experimental results for different designs of retro-reflectors in both water and LBE. We discuss both linear and array retro-reflectors of different sizes and investigate the influence of the main relevant ultrasonic parameters such as wavelength and spot size on the strength of the received reflection under different alignment angles. We also demonstrate how retro-reflective surfaces can be exploited when localizing objects using linear and rotating scanning methods. (authors)

  12. Modified polarimetric bidirectional reflectance distribution function with diffuse scattering: surface parameter estimation

    Science.gov (United States)

    Zhan, Hanyu; Voelz, David G.

    2016-12-01

    The polarimetric bidirectional reflectance distribution function (pBRDF) describes the relationships between incident and scattered Stokes parameters, but the familiar surface-only microfacet pBRDF cannot capture diffuse scattering contributions and depolarization phenomena. We propose a modified pBRDF model with a diffuse scattering component developed from the Kubelka-Munk and Le Hors et al. theories, and apply it in the development of a method to jointly estimate refractive index, slope variance, and diffuse scattering parameters from a series of Stokes parameter measurements of a surface. An application of the model and estimation approach to experimental data published by Priest and Meier shows improved correspondence with measurements of normalized Mueller matrix elements. By converting the Stokes/Mueller calculus formulation of the model to a degree of polarization (DOP) description, the estimation results of the parameters from measured DOP values are found to be consistent with a previous DOP model and results.

  13. Barium fluoride surface preparation, analysis and UV reflective coatings at Lawrence Livermore National Laboratory

    International Nuclear Information System (INIS)

    Wuest, C.R.

    1992-01-01

    Lawrence Livermore National Laboratory (LLNL) has begun a program of study on barium fluoride scintillating crystals for the Barium Fluoride Electromagnetic Calorimeter Collaboration. This program has resulted in a number of significant improvements in the mechanical processing, polishing and coating of barium fluoride crystals. Techniques have been developed using diamond-loaded pitch lapping that can produce 15 angstrom RMS surface finishes over large areas. These lapped surfaces have been shown to be crystalline using Rutherford Back-scattering (RBS). Also, special polishing fixtures have been designed based on mounting technology developed for the 1.1 m diameter optics used in LLNL's Nova Laser. These fixtures allow as many as five 25--50 cm long barium fluoride crystals to be polished and lapped at a time with the necessary tolerances for the 16,000 crystal Barium Fluoride Calorimeter. In addition, results will be presented on coating barium fluoride with UV reflective layers of magnesium fluoride and aluminum

  14. Interaction of mineral surfaces with simple organic molecules by diffuse reflectance IR spectroscopy (DRIFT)

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Joan E.; Kelley, Michael J.

    2008-06-01

    Diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS) was used to characterize multi-layers of lysine, glutamic acid and salicylic acid on -alumina and kaolinite surfaces. The results agreed well with those previously obtained by ATR-IR in aqueous media where available, indicating that DRIFT may be regarded as effectively an in-situ spectroscopy for these materials. In the case of salicylic acid adsorption onto γ-alumina, DRIFTS was used to identify monolayer coverage and to detect molecules down to coverage of 3% of a monolayer. The spectroscopic results as to coverage were confirmed by analysis of the solutions used for treatment. The spectra obtained allowed identification of changes in the bonding environment with increasing surface coverage. DRIFTS, offers several advantages in terms of materials, experimental technique and data treatment, motivating further investigations.

  15. Enhanced Group Delay of the Pulse Reflection with Graphene Surface Plasmon via Modified Otto Configuration

    Directory of Open Access Journals (Sweden)

    Guimei Li

    2017-01-01

    Full Text Available In this paper, the group delay of the transverse magnetic (TM polarized wave reflected from a modified Otto configuration with graphene surface plasmon is investigated theoretically. The findings show that the optical group delay in this structure can be enhanced negatively and can be switched from negative to positive due to the excitation of surface plasmon by graphene. It is clear that the negative group delay can be actively tuned through the Fermi energy of the graphene. Furthermore, the delay properties can also be manipulated by changing either the relaxation time of graphene or the distance between the coupling prism and the graphene. These tunable delay characteristics are promising for fabricating grapheme-based optical delay devices and other applications in the terahertz regime.

  16. Calibration of an integrated land surface process and radiobrightness (LSP/R) model during summertime

    Science.gov (United States)

    Judge, Jasmeet; England, Anthony W.; Metcalfe, John R.; McNichol, David; Goodison, Barry E.

    2008-01-01

    In this study, a soil vegetation and atmosphere transfer (SVAT) model was linked with a microwave emission model to simulate microwave signatures for different terrain during summertime, when the energy and moisture fluxes at the land surface are strong. The integrated model, land surface process/radiobrightness (LSP/R), was forced with weather and initial conditions observed during a field experiment. It simulated the fluxes and brightness temperatures for bare soil and brome grass in the Northern Great Plains. The model estimates of soil temperature and moisture profiles and terrain brightness temperatures were compared with the observed values. Overall, the LSP model provides realistic estimates of soil moisture and temperature profiles to be used with a microwave model. The maximum mean differences and standard deviations between the modeled and the observed temperatures (canopy and soil) were 2.6 K and 6.8 K, respectively; those for the volumetric soil moisture were 0.9% and 1.5%, respectively. Brightness temperatures at 19 GHz matched well with the observations for bare soil, when a rough surface model was incorporated indicating reduced dielectric sensitivity to soil moisture by surface roughness. The brightness temperatures of the brome grass matched well with the observations indicating that a simple emission model was sufficient to simulate accurate brightness temperatures for grass typical of that region and surface roughness was not a significant issue for grass-covered soil at 19 GHz. Such integrated SVAT-microwave models allow for direct assimilation of microwave observations and can also be used to understand sensitivity of microwave signatures to changes in weather forcings and soil conditions for different terrain types.

  17. Selecting the optimum number of partial least squares components for the calibration of attenuated total reflectance-mid-infrared spectra of undesigned kerosene samples.

    Science.gov (United States)

    Gómez-Carracedo, M P; Andrade, J M; Rutledge, D N; Faber, N M

    2007-03-07

    Selecting the correct dimensionality is critical for obtaining partial least squares (PLS) regression models with good predictive ability. Although calibration and validation sets are best established using experimental designs, industrial laboratories cannot afford such an approach. Typically, samples are collected in an (formally) undesigned way, spread over time and their measurements are included in routine measurement processes. This makes it hard to evaluate PLS model dimensionality. In this paper, classical criteria (leave-one-out cross-validation and adjusted Wold's criterion) are compared to recently proposed alternatives (smoothed PLS-PoLiSh and a randomization test) to seek out the optimum dimensionality of PLS models. Kerosene (jet fuel) samples were measured by attenuated total reflectance-mid-IR spectrometry and their spectra where used to predict eight important properties determined using reference methods that are time-consuming and prone to analytical errors. The alternative methods were shown to give reliable dimensionality predictions when compared to external validation. By contrast, the simpler methods seemed to be largely affected by the largest changes in the modeling capabilities of the first components.

  18. Improved Near-surface Velocity Models from Waveform Tomography Applied to Vibroseis MCS Reflection Data

    Science.gov (United States)

    Smithyman, B.; Clowes, R. M.

    2009-12-01

    Multichannel vibroseis reflection surveys are prevalent in the land exploration seismic industry because of benefits in speed and cost, along with reduced environmental impact when compared to explosive sources. Since the downgoing energy must travel through the shallow subsurface, an improved model of near-surface velocity can in theory substantially improve the resolution of deeper reflections. We describe techniques aimed at allowing the use of vibroseis data for long-offset refraction processing of first-arrival traveltimes and waveforms. Refraction processing of surface vibroseis data is typically limited to near-offset refraction statics. Velocity models of the shallow subsurface can be built to facilitate CDP stacking and migration, but these models are typically coarse and of limited use for interpretation. Waveform tomography combines inversion of first-arrival traveltime data with full waveform inversion of densely-sampled refracted arrivals. Since inversion of the waveform amplitude and phase is not limited by the ray-theory approximation, identification of low-velocity zones and small scattering targets is possible. Incorporating a wide range of offsets is critical for a more complete characterization of the near-surface. Because of the use of a non-linear frequency-domain approach to the solution of this inverse problem, low data frequencies are important in comparison with conventional reflection processing. Through the use of waveform tomography, we plan to build useful, detailed near-surface velocity models for both the reflection work flow and direct interpretation. Several difficulties exist in first-arrival analysis and waveform inversion of vibroseis data. The mixed-phase vibroseis source signature exhibits variations in phase with offset that are difficult to quantify without detailed a priori knowledge of the near-surface. This causes difficulties with picking and initial model building, which is critical for non-linear waveform inversion. A

  19. Estimation of Melt Ponds over Arctic Sea Ice using MODIS Surface Reflectance Data

    Science.gov (United States)

    Ding, Y.; Cheng, X.; Liu, J.

    2017-12-01

    Melt ponds over Arctic sea ice is one of the main factors affecting variability of surface albedo, increasing absorption of solar radiation and further melting of snow and ice. In recent years, a large number of melt ponds have been observed during the melt season in Arctic. Moreover, some studies have suggested that late spring to mid summer melt ponds information promises to improve the prediction skill of seasonal Arctic sea ice minimum. In the study, we extract the melt pond fraction over Arctic sea ice since 2000 using three bands MODIS weekly surface reflectance data by considering the difference of spectral reflectance in ponds, ice and open water. The preliminary comparison shows our derived Arctic-wide melt ponds are in good agreement with that derived by the University of Hamburg, especially at the pond distribution. We analyze seasonal evolution, interannual variability and trend of the melt ponds, as well as the changes of onset and re-freezing. The melt pond fraction shows an asymmetrical growth and decay pattern. The observed melt ponds fraction is almost within 25% in early May and increases rapidly in June and July with a high fraction of more than 40% in the east of Greenland and Beaufort Sea. A significant increasing trend in the melt pond fraction is observed for the period of 2000-2017. The relationship between melt pond fraction and sea ice extent will be also discussed. Key Words: melt ponds, sea ice, Arctic

  20. LBA-ECO CD-34 Hyperion 30-m Surface Reflectance, Amazon Basin: 2002-2005

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set contains 20 multispectral surface reflectance images collected by the EO-1 satellite Hyperion sensor at 30-m resolution and covering the...

  1. OMI/Aura Surface Reflectance Climatology Level 3 Global 0.5deg Lat/Lon Grid V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI Earth Surface Reflectance Climatology product, OMLER (Global 0.5deg Lat/Lon grid) which is based on Version 003 Level-1B top of atmosphere upwelling radiance...

  2. CLPX-Satellite: EO-1 Hyperion Surface Reflectance, Snow-Covered Area, and Grain Size, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of apparent surface reflectance, subpixel snow-covered area, and grain size collected from the Hyperion hyperspectral imager. The Hyperion...

  3. MODIS/Aqua Surface Reflectance Daily L2G Global 1km and 500m SIN Grid V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MYD09GA Version 6 product provides an estimate of the surface spectral reflectance of AQUA MODIS Bands 1-7 corrected for atmospheric conditions such as gasses,...

  4. MODIS/Terra Surface Reflectance Daily L2G Global 1km and 500m SIN Grid V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MOD09GA Version 6 product provides an estimate of the surface spectral reflectance of Terra MODIS Bands 1-7 corrected for atmospheric conditions such as gasses,...

  5. Plasma surface reflectance spectroscopy for non-invasive and continuous monitoring of extracellular component of blood

    Science.gov (United States)

    Sakota, Daisuke; Takatani, Setsuo

    2012-04-01

    To achieve the quantitative optical non-invasive diagnosis of blood during extracorporeal circulation therapies, the instrumental technique to extract extracellular spectra from whole blood was developed. In the circuit, the continuous blood flow was generated by a centrifugal blood pump. The oxygen saturation was maintained 100% by an oxygenator. The developed glass optical flow cell was attached to the outlet tubing of the oxygenator. The halogen lamp including the light from 400 to 900 nm wavelength was used for the light source. The light was guided into an optical fiber. The light emitted by the fiber was collimated and emitted to the flow cell flat surface at the incident angle of 45 degrees. The light just reflected on the boundary between inner surface of the flow cell and plasma at 45 degrees was detected by the detection fiber. The detected light was analyzed by a spectral photometer. The obtained spectrum from 400 to 600nm wavelength was not changed with respect to the hematocrit. In contrast, the signal in the spectral range was changed when the plasma free hemoglobin increased. By using two spectral range, 505+/-5 nm and 542.5+/-2.5 nm, the differential spectrum was correlated with the free hemoglobin at R2=0.99. On the other hand, as for the hematocrit, the differential spectrum was not correlated at R2=0.01. Finally, the plasma free hemoglobin was quantified with the accuracy of 22+/-19mg/dL. The result shows that the developed plasma surface reflectance spectroscopy (PSRS) can extract the plasma spectrum from flowing whole blood.

  6. A prototype for automation of land-cover products from Landsat Surface Reflectance Data Records

    Science.gov (United States)

    Rover, J.; Goldhaber, M. B.; Steinwand, D.; Nelson, K.; Coan, M.; Wylie, B. K.; Dahal, D.; Wika, S.; Quenzer, R.

    2014-12-01

    Landsat data records of surface reflectance provide a three-decade history of land surface processes. Due to the vast number of these archived records, development of innovative approaches for automated data mining and information retrieval were necessary. Recently, we created a prototype utilizing open source software libraries for automatically generating annual Anderson Level 1 land cover maps and information products from data acquired by the Landsat Mission for the years 1984 to 2013. The automated prototype was applied to two target areas in northwestern and east-central North Dakota, USA. The approach required the National Land Cover Database (NLCD) and two user-input target acquisition year-days. The Landsat archive was mined for scenes acquired within a 100-day window surrounding these target dates, and then cloud-free pixels where chosen closest to the specified target acquisition dates. The selected pixels were then composited before completing an unsupervised classification using the NLCD. Pixels unchanged in pairs of the NLCD were used for training decision tree models in an iterative process refined with model confidence measures. The decision tree models were applied to the Landsat composites to generate a yearly land cover map and related information products. Results for the target areas captured changes associated with the recent expansion of oil shale production and agriculture driven by economics and policy, such as the increase in biofuel production and reduction in Conservation Reserve Program. Changes in agriculture, grasslands, and surface water reflect the local hydrological conditions that occurred during the 29-year span. Future enhancements considered for this prototype include a web-based client, ancillary spatial datasets, trends and clustering algorithms, and the forecasting of future land cover.

  7. Light depolarization in off-specular reflection on submicro rough metal surfaces with imperfectly random roughness.

    Science.gov (United States)

    Liu, Linsheng; Li, Xuefeng; Nonaka, Kazuhiro

    2015-02-01

    Depolarization at a rough surface relates to its roughness and irregularity (e.g., sags and crests) besides the material property. However, there is still lack of general theory to clearly describe the relationship between depolarization ratios and surface conditions, and one important reason is that the mechanism of depolarization relates to geometric parameters such as microcosmic height/particle distributions of sub-micro to nm levels. To study the mechanism in more detail, a compact laser instrument is developed, and depolarization information of a linearly polarized incident light is used for analyzing the roughness, during which a He-Ne laser source (λ = 632.8 nm) is used. Three nickel specimens with RMS roughness (Rq) less than λ/4 are fabricated and tested. Six different areas in each specimen are characterized in detail using an AFM. Rq are in the range of 34.1-155.0 nm, and the heights are non-Gaussian distribution in the first specimen and near-Gaussian distribution in the others. Off-specular inspection is carried out exactly on these 18 characterized areas, and results show that the cross-polarization ratios match quite well with Rq values of the first sample that has Rq ≤ λ/10 (or Rt ≤ λ), while they match well with maximum height, Rt, values of the other two that have Rt > λ (the maximum derivation is 11%). In addition, since this instrument is simple, portable, stable, and low-cost, it has great potential for practical online roughness testing after a linear calibration.

  8. 30-m Land Surface Albedo by Integrating Landsat directional reflectance and MODIS anisotropic information

    Science.gov (United States)

    Shuai, Y.; Masek, J. G.; Gao, F.; Schaaf, C.; Williams, C. A.; Wang, Z.

    2012-12-01

    Land surface albedo as a key physical variable determining the solar energy absorbed by the land surface, and can affect climate through ecosystem feedback processes. Some studies have highlighted that positive radiative forcing (warming) induced by increased forest cover and decreased albedo in temperate and boreal forest regions could offset the negative forcing expected from carbon sequestration (Betts 2000). However, these studies have not used data at the spatial resolution of human land dynamics (e.g. 30m Landsat resolution). Therefore, there is a need for improved estimates of land surface albedo at high resolution to fully understand the role of land cover change in climate forcing and carbon cycle. Following our initial "concurrent" approach applied to Landsat data acquired during the post-2000 MODIS era (Shuai et al.2011), we have developed a "pre-MODIS era" approach to generate 30-meter albedos using Landsat surface directional reflectance (1970s-2000) and Look-Up-Tables (LUT) of anisotropy information extracted from MODIS BRDF data. We use a NLCD (National Land Cover Dataset)-class-based LUT for non-disturbed land cover. Disturbed forest patches are identified from the Monitoring Trends in Burn Severity (MTBS) and North American Forest Dynamics (NAFD) datasets. For each category, high quality MODIS BRDF parameters (MCD43A1 product) are retrieved and used to populate the LUT. Each entry in the LUT reflects a unique combination of land cover type, disturbance age and type, season/month, and sensor bands. The initial BRDF LUT generated for the Pacific Northwest of the United States exhibits various BRDF evolution trajectories for disturbed classes, including different recovery trajectories for fire and non-fire disturbance. The albedo-to-nadir-ratio method (Shuai et al., 2011) is applied to the BRDF LUT to calculate spectral albedos, followed by a narrow-to-broadband conversion (Liang 2000) to generate broad-band shortwave albedo. Our preliminary

  9. X-ray Reflectivity Study of Ionic Liquids at Electrified Surfaces

    Science.gov (United States)

    Chu, Miaoqi

    X-ray reflectivity (XRR) versatile technique that characterize the surface structures. However, due to the lack of phase information of X-ray data, the reconstruction of electron density profile (EDP) from XRR data is an ill-posed inverse problem that requires extra attention. In Chapter 1, several key concepts in XRR data analysis are reviewed. The typical XRR data acquisition procedure and methods of modeling electron density are introduced. The widely used logarithm form of merit function is justified with mathematical deduction and numerical experiment. A scheme that generates artificial reflectivity data with theoretical statistical error but not systematical error is proposed. With the methods and schemes described in Chapter 1, simulated reflectivity data of a simple one-slab model is generated and fitted to test the efficient of EDP reconstruction. By isolating the parameters, the effects of slab width, electron density contrast and maximal wave transfer are studied individually. It?s demonstrated that best-fit/global minima, result reported by most XRR studies, don?t necessary reflect the real EDP. By contrast, mapping the merit function in the parametric space can capture much more details. Additionally, the widely accepted concept about the XRR theoretical spatial resolution (pi/q_{max}) as well the using Patterson function are brought to test. In the perspective of XRR data analysis, this chapter puts forward general rules to design and optimize XRR experiments. It also demonstrates how susceptible the fitting result will be if it?s not done carefully. In Chapter 3, the interface between hydrophobic OTS film and several solvents is studied with XRR in a transmission-cell setup. The solvents, from water, acetone, to alcohol (methanol, ethanol, 1-propanol), to alkane (pentane, hexane and heptane), vary significantly in terms of polarity and hydrogen bonding. However, the XRR data from different solvents are subtle. The methods and principles elicited in

  10. NuSTAR on-ground calibration I: Imaging quality

    DEFF Research Database (Denmark)

    Westergaard, Niels Jørgen Stenfeldt; Madsen, Kristin K.; Brejnholt, Nicolai

    2012-01-01

    metrology provided surface maps of the reflecting surfaces. Several flight coated mirrors were brought to BNL for scattering measurements. The information from both sources is fed to a raytracing code that is tested against the on-ground calibration data. The code is subsequently used for predicting...... the imaging properties for X-ray sources at infinite distance. © 2012 SPIE....

  11. Neutron reflectivity study of substrate surface chemistry effects on supported phospholipid bilayer formation on (1120) sapphire.

    Energy Technology Data Exchange (ETDEWEB)

    Oleson, Timothy A. [University of Wisconsin, Madison; Sahai, Nita [University of Akron; Wesolowski, David J [ORNL; Dura, Joseph A [ORNL; Majkrzak, Charles F [ORNL; Giuffre, Anthony J. [University of Wisconsin, Madison

    2012-01-01

    Oxide-supported phospholipid bilayers (SPBs) used as biomimetric membranes are significant for a broad range of applications including improvement of biomedical devices and biosensors, and in understanding biomineralization processes and the possible role of mineral surfaces in the evolution of pre-biotic membranes. Continuous-coverage and/or stacjed SPBs retain properties (e.,g. fluidity) more similar to native biological membranes, which is desirable for most applications. Using neutron reflectivity, we examined face coverage and potential stacking of dipalmitoylphosphatidylcholine (DPPC) bilayers on the (1120) face of sapphire (a-Al2O3). Nearly full bilayers were formed at low to neutral pH, when the sapphire surface is positively charged, and at low ionic strength (l=15 mM NaCl). Coverage decreased at higher pH, close to the isoelectric point of sapphire, and also at high I>210mM, or with addition of 2mM Ca2+. The latter two effects are additive, suggesting that Ca2+ mitigates the effect of higher I. These trends agree with previous results for phospholipid adsorption on a-Al2O3 particles determined by adsorption isotherms and on single-crystal (1010) sapphire by atomic force microscopy, suggesting consistency of oxide surface chemistry-dependent effects across experimental techniques.

  12. Different size biomolecules anchoring on porous silicon surface: fluorescence and reflectivity pores infiltration comparative studies

    Energy Technology Data Exchange (ETDEWEB)

    Giovannozzi, Andrea M.; Rossi, Andrea M. [National Institute for Metrological Research, Thermodynamic Division, Strada delle Cacce 91, 10135 Torino (Italy); Renacco, Chiara; Farano, Alessandro [Ribes Ricecrhe Srl, Via Lavoratori Vittime del Col du Mont 24, 11100 Aosta (Italy); Derosas, Manuela [Biodiversity Srl, Via Corfu 71, 25124 Brescia (Italy); Enrico, Emanuele [National Institute for Metrological Research, Electromagnetism Division, Strada delle Cacce 91, 10135 Torino (Italy)

    2011-06-15

    The performance of porous silicon optical based biosensors strongly depends on material nanomorphology, on biomolecules distribution inside the pores and on the ability to link sensing species to the pore walls. In this paper we studied the immobilization of biomolecules with different size, such as antibody anti aflatoxin (anti Aflatox Ab, {proportional_to}150 KDa), malate dehydrogenase (MDH, {proportional_to}36KDa) and metallothionein (MT, {proportional_to}6KDa) at different concentrations on mesoporous silicon samples ({proportional_to}15 nm pores diameter). Fluorescence measurements using FITC- labeled biomolecules and refractive index analysis based on reflectivity spectra have been employed together to detect the amount of proteins bound to the surface and to evaluate their diffusion inside the pores. Here we suggest that these two techniques should be used together to have a better understanding of what happens at the porous silicon surface. In fact, when pores dimensions are not perfectly tuned to the protein size a higher fluorescence signal doesn't often correspond to a higher biomolecules distribution inside the pores. When a too much higher concentration of biomolecule is anchored on the surface, steric crowd effects and repulsive interactions probably take over and hinder pores infiltration, inducing a small or absent shift in the fringe pattern even if a higher fluorescence signal is registered. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Attenuated total reflectance Fourier-transform infrared spectroscopy of carboxylic acids adsorbed onto mineral surfaces

    Science.gov (United States)

    Kubicki, J. D.; Schroeter, L. M.; Itoh, M. J.; Nguyen, B. N.; Apitz, S. E.

    1999-09-01

    A suite of naturally-occurring carboxylic acids (acetic, oxalic, citric, benzoic, salicylic and phthalic) and their corresponding sodium salts were adsorbed onto a set of common mineral substrates (quartz, albite, illite, kaolinite and montmorillonite) in batch slurry experiments. Solution pH's of approximately 3 and 6 were used to examine the effects of pH on sorption mechanisms. Attenuated total reflectance Fourier-transform infrared (ATR FTIR) spectroscopy was employed to obtain vibrational frequencies of the organic ligands on the mineral surfaces and in solution. UV/visible spectroscopy on supernatant solutions was also employed to confirm that adsorption from solution had taken place for benzoic, salicylic and phthalic acids. Molecular orbital calculations were used to model possible surface complexes and interpret the experimental spectra. In general, the tectosilicates, quartz and albite feldspar, did not chemisorb (i.e., strong, inner-sphere adsorption) the carboxylate anions in sufficient amounts to produce infrared spectra of the organics after rinsing in distilled water. The clays (illite, kaolinite and montmorillonite) each exhibited similar ATR FTIR spectra. However, the illite sample used in this study reacted to form strong surface and aqueous complexes with salicylic acid before being treated to remove free Fe-hydroxides. Chemisorption of carboxylic acids onto clays is shown to be limited without the presence of Fe-hydroxides within the clay matrix.

  14. TOPOGRAPHIC LOCAL ROUGHNESS EXTRACTION AND CALIBRATION OVER MARTIAN SURFACE BY VERY HIGH RESOLUTION STEREO ANALYSIS AND MULTI SENSOR DATA FUSION

    Directory of Open Access Journals (Sweden)

    J. R. Kim

    2012-08-01

    Full Text Available The planetary topography has been the main focus of the in-orbital remote sensing. In spite of the recent development in active and passive sensing technologies to reconstruct three dimensional planetary topography, the resolution limit of range measurement is theoretically and practically obvious. Therefore, the extraction of inner topographical height variation within a measurement spot is very challengeable and beneficial topic for the many application fields such as the identification of landform, Aeolian process analysis and the risk assessment of planetary lander. In this study we tried to extract the topographic height variation over martian surface so called local roughness with different approaches. One method is the employment of laser beam broadening effect and the other is the multi angle optical imaging. Especially, in both cases, the precise pre processing employing high accuracy DTM (Digital Terrain Model were introduced to minimise the possible errors. Since a processing routine to extract very high resolution DTMs up to 0.5–4m grid-spacing from HiRISE (High Resolution Imaging Science Experiment and 20–10m DTM from CTX (Context Camera stereo pair has been developed, it is now possible to calibrate the local roughness compared with the calculated height variation from very high resolution topographic products. Three testing areas were chosen and processed to extract local roughness with the co-registered multi sensor data sets. Even though, the extracted local roughness products are still showing the strong correlation with the topographic slopes, we demonstrated the potentials of the height variations extraction and calibration methods.

  15. Recent Developments in the X-Ray Reflectivity Analysis for Rough Surfaces and Interfaces of Multilayered Thin Film Materials

    Directory of Open Access Journals (Sweden)

    Yoshikazu Fujii

    2013-01-01

    Full Text Available X-ray reflectometry is a powerful tool for investigations on rough surface and interface structures of multilayered thin film materials. The X-ray reflectivity has been calculated based on the Parratt formalism, accounting for the effect of roughness by the theory of Nevot-Croce conventionally. However, in previous studies, the calculations of the X-ray reflectivity often show a strange effect where interference effects would increase at a rough surface. And estimated surface and interface roughnesses from the X-ray reflectivity measurements did not correspond to the TEM image observation results. The strange result had its origin in a used equation due to a serious mistake in which the Fresnel transmission coefficient in the reflectivity equation is increased at a rough interface because of a lack of consideration of diffuse scattering. In this review, a new accurate formalism that corrects this mistake is presented. The new accurate formalism derives an accurate analysis of the X-ray reflectivity from a multilayer surface of thin film materials, taking into account the effect of roughness-induced diffuse scattering. The calculated reflectivity by this accurate reflectivity equation should enable the structure of buried interfaces to be analyzed more accurately.

  16. A sea surface reflectance model for (A)ATSR, and application to aerosol retrievals

    Science.gov (United States)

    Sayer, A. M.; Thomas, G. E.; Grainger, R. G.

    2010-07-01

    A model of the sea surface bidirectional reflectance distribution function (BRDF) is presented for the visible and near-IR channels (over the spectral range 550 nm to 1.6 μm) of the dual-viewing Along-Track Scanning Radiometers (ATSRs). The intended application is as part of the Oxford-RAL Aerosols and Clouds (ORAC) retrieval scheme. The model accounts for contributions to the observed reflectance from whitecaps, sun-glint and underlight. Uncertainties in the parametrisations used in the BRDF model are propagated through into the forward model and retrieved state. The new BRDF model offers improved coverage over previous methods, as retrievals are possible into the sun-glint region, through the ATSR dual-viewing system. The new model has been applied in the ORAC aerosol retrieval algorithm to process Advanced ATSR (AATSR) data from September 2004 over the south-eastern Pacific. The assumed error budget is shown to be generally appropriate, meaning the retrieved states are consistent with the measurements and a priori assumptions. The resulting field of aerosol optical depth (AOD) is compared with colocated MODIS-Terra observations, AERONET observations at Tahiti, and cruises over the oceanic region. MODIS and AATSR show similar spatial distributions of AOD, although MODIS reports values which are larger and more variable. It is suggested that assumptions in the MODIS aerosol retrieval algorithm may lead to a positive bias in MODIS AOD of order 0.01 at 550 nm over ocean regions where the wind speed is high.

  17. Online Monitoring of Laser-Generated XUV Radiation Spectra by Surface Reflectivity Measurements with Particle Detectors

    Directory of Open Access Journals (Sweden)

    Andreas Hoffmann

    2017-01-01

    Full Text Available In this contribution, we present a wavelength-sensitive method for the detection of extreme ultraviolet (XUV photon energies between 30 eV and 120 eV. The method is based on 45° reflectivity from either a cesium iodide-coated or an uncoated metal surface, which directs the XUV beam onto an electron or ion detector and its signal is used to monitor the XUV beam. The benefits of our approach are a spectrally sensitive diagnosis of the XUV radiation at the interaction place of time-resolved XUV experiments and the detection of infrared leak light though metal filters in high-harmonic generation (HHG experiments. Both features were tested using spectrally shaped XUV pulses from HHG in a capillary, and we have achieved excellent agreement with XUV spectrometer measurements and reflectivity calculations. Our obtained results are of interest for time-resolved XUV experiments presenting an additional diagnostic directly in the interaction region and for small footprint XUV beamline diagnostics.

  18. Mixed polymer conductors for control of microwave reflectivity surfaces. Volume I

    International Nuclear Information System (INIS)

    Despotakis, A.

    1998-06-01

    The preparation and characterisation of polyaniline-silver-polymer electrolyte composite materials are described and their potential application as large area surfaces with microwave reflection/transmission controlled by application of an electric field ('microwave shutters') is investigated. The component polymer electrolyte (largely polyether-silver salt) and the polyaniline-silver salt mixtures have been separately investigated using a range of spectroscopic, microscopic and electrical impedance techniques. The redox behaviour of polyaniline versus silver in various cells incorporating polymer electrolytes have been studied in both ambient and 'dry' nitrogen environments using cyclic voltammetry and square wave potentiometry. It is proposed that the redox behaviour in dry nitrogen conditions involves the formation of leucoemeraldine-Ag + complex. This promotes the spontaneous reduction of emeraldine salt to leucoemeraldine by silver metal in contrast to the equilibrium status of the system in ambient conditions. In ambient conditions, the emeraldine undergoes an acid-base transition in the presence of silver salt (with(out) elemental silver). Furthermore, X-ray analysis has revealed that it is possible to chemically generate elemental silver after mixing its silver salt with the emeraldine (either salt or base form) in ambient conditions. Discs of various polyaniline-silver-polymer electrolyte compositions have been reported. Significant and rapid changes in microwave reflectivities have been observed. The mechanisms of electrochemical changes within the composites have been discussed and a 'cascade' process for the propagation of the switching effect across the areas of the discs has been proposed. (author)

  19. Relationship between the velvet-like texture of flower petals and light reflection from epidermal cell surfaces.

    Science.gov (United States)

    Zhang, Yang; Sun, Tianxun; Xie, Linan; Hayashi, Takahiro; Kawabata, Saneyuki; Li, Yuhua

    2015-07-01

    Texture such as velvet lustre contributes to the ornamental character of a flower, along with shape and colour. This study aims to clarify the relationship between the formation of the velvet lustre texture and the optical characteristics of light reflection from irradiated surfaces of velvety and non-velvety petals from 30 cultivars or varieties of ornamental plants representing 19 species from various families. The angle of incident light from the petal surface was set at 90°, 60° or 30°, then light reflection from the petal surfaces was observed using a digital microscope. The observed reflected light was composed of "exterior" reflected light (ERL), which is observed as sparkling white spots on the surface of the epidermal cells, and "interior" reflected light (IRL), which is reflected from inside the petal and determines the base colour of the petals. Velvety petals had two common characteristics: conical-papillate or domed epidermal cells and a dark colour. As the angle between the petal and the incident light decreased, the ERL spots took on a belt-like shape, and total ERL intensity became stronger. We concluded that the velvety texture is derived from characteristic ERL rays coupled with dark IRL. The long sloping surface of the epidermal cells contributes to the higher ERL intensity as petals are observed from more horizontal angles, causing characteristic reverse shading effects on velvety petals.

  20. Influence of aerosol and surface reflectance variability on hyperspectral observed radiance

    Directory of Open Access Journals (Sweden)

    C. Bassani

    2012-06-01

    Full Text Available Current aerosol retrievals based on visible and near infrared remote-sensing, are prone to loss of accuracy, where the assumptions of the applied algorithm are violated. This happens mostly over land and it is related to misrepresentation of specific aerosol conditions or surface properties. New satellite missions, based on high spectral resolution instruments, such as PRISMA (Hyperspectral Precursor of the Application Mission, represent a valuable opportunity to improve the accuracy of τa550 retrievable from a remote-sensing system developing new atmospheric measurement techniques. This paper aims to address the potential of these new observing systems in more accurate retrieving τa550, specifically over land in heterogeneous and/or homogeneous areas composed by dark and bright targets. The study shows how the variation of the hyperspectral observed radiance can be addressed to recognise a variation of Δτa550 = 0.02. The goal has been achieved by using simulated radiances by combining two aerosol models (urban and continental and two reflecting surfaces: dark (represented by water and bright (represented by sand for the PRISMA instrument, considering the environmental contribution of the observed radiance, i.e., the adjacency effect. Results showed that, in the continental regime, the expected instrument sensitivity would allow for retrieval accuracy of the aerosol optical thickness at 550 nm of 0.02 or better, with a dark surface surrounded by dark areas. The study also showed that for the urban regime, the surface plays a more significant role, with a bright surface surrounded by dark areas providing favourable conditions for the aerosol load retrievals, and dark surfaces representing less suitable situations for inversion independently of the surroundings. However, over all, the results obtained provide evidence that high resolution observations of Earth spectrum between

  1. Continuity of Reflectance Data between Landsat-7 ETM+ and Landsat-8 OLI, for Both Top-of-Atmosphere and Surface Reflectance: A Study in the Australian Landscape

    Directory of Open Access Journals (Sweden)

    Neil Flood

    2014-08-01

    Full Text Available The new Landsat-8 Operational Land Imager (OLI is intended to be broadly compatible with the previous Landsat-7 Enhanced Thematic Mapper Plus (ETM+. The spectral response of the OLI is slightly different to the ETM+, and so there may be slight differences in the reflectance measurements. Since the differences are a function not just of spectral responses, but also of the target pixels, there is a need to assess these differences in practice, using imagery from the area of interest. This paper presents a large scale study of the differences between ETM+ and OLI in the Australian landscape. The analysis is carried out in terms of both top-of-atmosphere and surface reflectance, and also in terms of biophysical parameters modelled from those respective reflectance spectra. The results show small differences between the sensors, which can be magnified by modelling to a biophysical parameter. It is also shown that a part of this difference appears to be systematic, and can be reliably removed by regression equations to predict ETM+ reflectance from OLI reflectance, before applying biophysical models. This is important when models have been fitted to historical field data coincident with ETM+ imagery. However, there will remain a small per-pixel difference which could be an unwanted source of variability.

  2. A hydrological prediction system based on the SVS land-surface scheme: efficient calibration of GEM-Hydro for streamflow simulation over the Lake Ontario basin

    Directory of Open Access Journals (Sweden)

    É. Gaborit

    2017-09-01

    Full Text Available This work explores the potential of the distributed GEM-Hydro runoff modeling platform, developed at Environment and Climate Change Canada (ECCC over the last decade. More precisely, the aim is to develop a robust implementation methodology to perform reliable streamflow simulations with a distributed model over large and partly ungauged basins, in an efficient manner. The latest version of GEM-Hydro combines the SVS (Soil, Vegetation and Snow land-surface scheme and the WATROUTE routing scheme. SVS has never been evaluated from a hydrological point of view, which is done here for all major rivers flowing into Lake Ontario. Two established hydrological models are confronted to GEM-Hydro, namely MESH and WATFLOOD, which share the same routing scheme (WATROUTE but rely on different land-surface schemes. All models are calibrated using the same meteorological forcings, objective function, calibration algorithm, and basin delineation. GEM-Hydro is shown to be competitive with MESH and WATFLOOD: the NSE  √  (Nash–Sutcliffe criterion computed on the square root of the flows is for example equal to 0.83 for MESH and GEM-Hydro in validation on the Moira River basin, and to 0.68 for WATFLOOD. A computationally efficient strategy is proposed to calibrate SVS: a simple unit hydrograph is used for routing instead of WATROUTE. Global and local calibration strategies are compared in order to estimate runoff for ungauged portions of the Lake Ontario basin. Overall, streamflow predictions obtained using a global calibration strategy, in which a single parameter set is identified for the whole basin of Lake Ontario, show accuracy comparable to the predictions based on local calibration: the average NSE  √  in validation and over seven subbasins is 0.73 and 0.61, respectively for local and global calibrations. Hence, global calibration provides spatially consistent parameter values, robust performance at gauged locations, and reduces the

  3. A hydrological prediction system based on the SVS land-surface scheme: efficient calibration of GEM-Hydro for streamflow simulation over the Lake Ontario basin

    Science.gov (United States)

    Gaborit, Étienne; Fortin, Vincent; Xu, Xiaoyong; Seglenieks, Frank; Tolson, Bryan; Fry, Lauren M.; Hunter, Tim; Anctil, François; Gronewold, Andrew D.

    2017-09-01

    This work explores the potential of the distributed GEM-Hydro runoff modeling platform, developed at Environment and Climate Change Canada (ECCC) over the last decade. More precisely, the aim is to develop a robust implementation methodology to perform reliable streamflow simulations with a distributed model over large and partly ungauged basins, in an efficient manner. The latest version of GEM-Hydro combines the SVS (Soil, Vegetation and Snow) land-surface scheme and the WATROUTE routing scheme. SVS has never been evaluated from a hydrological point of view, which is done here for all major rivers flowing into Lake Ontario. Two established hydrological models are confronted to GEM-Hydro, namely MESH and WATFLOOD, which share the same routing scheme (WATROUTE) but rely on different land-surface schemes. All models are calibrated using the same meteorological forcings, objective function, calibration algorithm, and basin delineation. GEM-Hydro is shown to be competitive with MESH and WATFLOOD: the NSE √ (Nash-Sutcliffe criterion computed on the square root of the flows) is for example equal to 0.83 for MESH and GEM-Hydro in validation on the Moira River basin, and to 0.68 for WATFLOOD. A computationally efficient strategy is proposed to calibrate SVS: a simple unit hydrograph is used for routing instead of WATROUTE. Global and local calibration strategies are compared in order to estimate runoff for ungauged portions of the Lake Ontario basin. Overall, streamflow predictions obtained using a global calibration strategy, in which a single parameter set is identified for the whole basin of Lake Ontario, show accuracy comparable to the predictions based on local calibration: the average NSE √ in validation and over seven subbasins is 0.73 and 0.61, respectively for local and global calibrations. Hence, global calibration provides spatially consistent parameter values, robust performance at gauged locations, and reduces the complexity and computation burden of the

  4. Automated sulcal depth measurement on cortical surface reflecting geometrical properties of sulci.

    Directory of Open Access Journals (Sweden)

    Hyuk Jin Yun

    Full Text Available Sulcal depth that is one of the quantitative measures of cerebral cortex has been widely used as an important marker for brain morphological studies. Several studies have employed Euclidean (EUD or geodesic (GED algorithms to measure sulcal depth, which have limitations that ignore sulcal geometry in highly convoluted regions and result in under or overestimated depth. In this study, we proposed an automated measurement for sulcal depth on cortical surface reflecting geometrical properties of sulci, which named the adaptive distance transform (ADT. We first defined the volume region of cerebrospinal fluid between the 3D convex hull and the cortical surface, and constructed local coordinates for that restricted region. Dijkstra's algorithm was then used to compute the shortest paths from the convex hull to the vertices of the cortical surface based on the local coordinates, which may be the most proper approach for defining sulcal depth. We applied our algorithm to both a clinical dataset including patients with mild Alzheimer's disease (AD and 25 normal controls and a simulated dataset whose shape was similar to a single sulcus. The mean sulcal depth in the mild AD group was significantly lower than controls (p = 0.007, normal [mean±SD]: 7.29±0.23 mm, AD: 7.11±0.29 and the area under the receiver operating characteristic curve was relatively high, showing the value of 0.818. Results from clinical dataset that were consistent with former studies using EUD or GED demonstrated that ADT was sensitive to cortical atrophy. The robustness against inter-individual variability of ADT was highlighted through simulation dataset. ADT showed a low and constant normalized difference between the depth of the simulated data and the calculated depth, whereas EUD and GED had high and variable differences. We suggest that ADT is more robust than EUD or GED and might be a useful alternative algorithm for measuring sulcal depth.

  5. Impacts of dust aerosol and adjacency effects on the accuracy of Landsat 8 and RapidEye surface reflectances

    KAUST Repository

    Houborg, Rasmus

    2017-03-29

    The atmospheric correction of satellite data is challenging over desert agricultural systems, due to the relatively high aerosol optical thicknesses (τ550), bright soils, and a heterogeneous surface reflectance field. Indeed, the contribution of reflected radiation from adjacent pixels scattered into the field of view of a target pixel is considerable and can significantly affect the fidelity of retrieved reflectances. In this study, uncertainties and quantitative errors associated with the atmospheric correction of multi-spectral Landsat 8 and RapidEye data were characterized over a desert agricultural landscape in Saudi Arabia. Surface reflectances were retrieved using an implementation of the 6SV atmospheric correction code, and validated against field collected spectroradiometer measurements over desert, cultivated soil, and vegetated surface targets. A combination of satellite and Aerosol Robotic Network (AERONET) data were used to parameterize aerosol properties and atmospheric state parameters. With optimal specification of τ550 and aerosol optical properties and correction for adjacency effects, the relative Mean Absolute Deviation (MAD) for all bands combined was 5.4% for RapidEye and 6.8% for Landsat 8. However uncertainties associated with satellite-based τ550 retrievals were shown to introduce significant error into the reflectance estimates. With respect to deriving common vegetation indices from corrected reflectance data, the Normalized Difference Vegetation Index (NDVI) was associated with the smallest errors (3–8% MAD). Surface reflectance errors were highest for bands in the visible part of the spectrum, particularly the blue band (5–16%), while there was more consistency within the red-edge (~ 5%) and near-infrared (5–7%). Results were generally better constrained when a τ550-dependent aerosol model for desert dust particles, parameterized on the basis of nearby AERONET site data, was used in place of a generic rural or background

  6. Updating Landsat time series of surface-reflectance composites and forest change products with new observations

    Science.gov (United States)

    Hermosilla, Txomin; Wulder, Michael A.; White, Joanne C.; Coops, Nicholas C.; Hobart, Geordie W.

    2017-12-01

    The use of time series satellite data allows for the temporally dense, systematic, transparent, and synoptic capture of land dynamics over time. Subsequent to the opening of the Landsat archive, several time series approaches for characterizing landscape change have been developed, often representing a particular analytical time window. The information richness and widespread utility of these time series data have created a need to maintain the currency of time series information via the addition of new data, as it becomes available. When an existing time series is temporally extended, it is critical that previously generated change information remains consistent, thereby not altering reported change statistics or science outcomes based on that change information. In this research, we investigate the impacts and implications of adding additional years to an existing 29-year annual Landsat time series for forest change. To do so, we undertook a spatially explicit comparison of the 29 overlapping years of a time series representing 1984-2012, with a time series representing 1984-2016. Surface reflectance values, and presence, year, and type of change were compared. We found that the addition of years to extend the time series had minimal effect on the annual surface reflectance composites, with slight band-specific differences (r ≥ 0.1) in the final years of the original time series being updated. The area of stand replacing disturbances and determination of change year are virtually unchanged for the overlapping period between the two time-series products. Over the overlapping temporal period (1984-2012), the total area of change differs by 0.53%, equating to an annual difference in change area of 0.019%. Overall, the spatial and temporal agreement of the changes detected by both time series was 96%. Further, our findings suggest that the entire pre-existing historic time series does not need to be re-processed during the update process. Critically, given the time

  7. Objective and Subjective Evaluation of Reflecting and Diffusing Surfaces in Auditoria

    Science.gov (United States)

    Cox, Trevor John

    Available from UMI in association with The British Library. Requires signed TDF. The performance of reflectors and diffusers used in auditoria have been evaluated both objectively and subjectively. Two accurate systems have been developed to measure the scattering from surfaces via the cross correlation function. These have been used to measure the scattering from plane panels, curved panels and quadratic residue diffusers (QRDs). The scattering measurements have been used to test theoretical prediction methods based on the Helmholtz-Kirchhoff integral equation. Accurate prediction methods were found for all surfaces tested. The limitations of the more approximate methods have been defined. The assumptions behind Schroeder's design of the QRD have been tested and the local reacting admittance assumption found to be valid over a wide frequency range. It was found that the QRD only produces uniform scattering at low frequencies. For an on-axis source the scattering from a curved panel was as good as from a QRD. For an oblique source the QRD produced much more uniform scattering than the curved panel. The subjective measurements evaluated the smallest perceivable change in the early sound field, the part most influenced by reflectors and diffusers. A natural sounding simulation of a concert hall field within an anechoic chamber was used. Standard objective parameters were reasonable values when compared to values found in real halls and subjective preference measurements. A difference limen was measured for early lateral energy fraction (.048 +/-.005); inter aural cross correlation (.075 +/-.008); clarity index (.67 +/-.13 dB); and centre time (8.6 +/- 1.6 ms). It was found that: (i) when changes are made to diffusers and reflectors, changes in spatial impression will usually be larger than those in clarity; and (ii) acousticians can gain most by paying attention to lateral sound in auditoria. It was also found that: (i) diffuse reflections in the early sound field

  8. Laboratory panel and radiometer calibration

    CSIR Research Space (South Africa)

    Deadman, AJ

    2011-07-01

    Full Text Available directly by Labsphere or are derived from comparison with other panels that have been calibrated by Labsphere. These 8?/hemispherical reflectance values are used when calculating the absolute reflectance of a test site. Two institutes South Dakota...

  9. Importance of including small-scale tile drain discharge in the calibration of a coupled groundwater-surface water catchment model

    DEFF Research Database (Denmark)

    Hansen, Anne Lausten; Refsgaard, Jens Christian; Christensen, Britt Stenhøj Baun

    2013-01-01

    the catchment. In this study, a coupled groundwater-surface water model based on the MIKE SHE code was developed for the 4.7 km2 Lillebæk catchment in Denmark, where tile drain flow is a major contributor to the stream discharge. The catchment model was calibrated in several steps by incrementally including...... the observation data into the calibration to see the effect on model performance of including diverse data types, especially tile drain discharge. For the Lillebæk catchment, measurements of hydraulic head, daily stream discharge, and daily tile drain discharge from five small (1–4 ha) drainage areas exist....... The results showed that including tile drain data in the calibration of the catchment model improved its general performance for hydraulic heads and stream discharges. However, the model failed to correctly describe the local-scale dynamics of the tile drain discharges, and, furthermore, including the drain...

  10. Specular and non-specular X-ray reflection from a single-crystal molybdenum mirror surface

    CERN Document Server

    Mizusawa, M

    2003-01-01

    The surface morphology of a super-polished mirror of single-crystal molybdenum has been studied by grazing-incidence X-ray reflection. It yields a rather high specular reflectivity (82.0%) for 16.0 keV X-rays below the critical angle. The data suggest that the mirror has a small roughness (0.7 nm rms) unlike other metal mirrors, but, on the other hand, strongly damaged layers (6.35 nm in total) exist at the near surface. It has been also found that the surface has a large correlation length (>3 mu m) and a small Hurst parameter (0.2-0.3) from the non-specular reflection.

  11. [Light reflection zone on the incisors' surface--a new parameter for smile esthetics evaluation].

    Science.gov (United States)

    Brezniak, N; Wasserstein, A; Shmuli, T

    2012-07-01

    The light reflection zone (LRZ) is a bright white dot or area that appears on the surface of the maxillary central incisors and/or the gingiva of the front teeth, visible in intra-oral and smile extra-oral photographs. Previously, a positive correlation between the location of the LRZ as observed in intra-oral frontal photographs and the inclination of the upper central incisors as measured on lateral headfims was found. The purpose of this study was to find whether this LRZ location can serve as a new parameter influencing the level of smile esthetics. Twelve pairs of facial photographs, including 10 of ordinary smiling persons and 2 of smiling models, were presented to 138 participants. The only difference between each pair was the location of the LRZ that was moved, compared to the original photograph, gingivally or incisally respectively, using Photoshop (Adobe). Each participant was asked to mark whether he/she noticed a difference between the 2 pictures, and if so, to score the nicer smile. Data analysis was carried out using Chi square test and Fisher's exact test (SPSS v17). The results showed that most of the participants did not recognize the differences between the pairs however, when differences were recognized, most of the participants pointed on the smile where the LRZ was located gingivally as the nicer one. This result was with statistical significance for the 2 models (p < 0.05), In conclusion, the LRZ is a new, yet unrecognized, parameter that can serve as a tool for the diagnosis of esthetic smile. The general population defines a nicer smile when the LRZ is located in the gingival area of the upper central incisors' surface rather than the incisal third. The LRZ should probably be studied not only in Orthodontics but also in other branches of dentistry.

  12. How Can Polarization States of Reflected Light from Snow Surfaces Inform Us on Surface Normals and Ultimately Snow Grain Size Measurements?

    Science.gov (United States)

    Schneider, A. M.; Flanner, M.; Yang, P.; Yi, B.; Huang, X.; Feldman, D.

    2016-12-01

    The Snow Grain Size and Pollution (SGSP) algorithm is a method applied to Moderate Resolution Imaging Spectroradiometer data to estimate snow grain size from space-borne measurements. Previous studies validate and quantify potential sources of error in this method, but because it assumes flat snow surfaces, however, large scale variations in surface normals can cause biases in its estimates due to its dependence on solar and observation zenith angles. To address these variations, we apply the Monte Carlo method for photon transport using data containing the single scattering properties of different ice crystals to calculate polarization states of reflected monochromatic light at 1500nm from modeled snow surfaces. We evaluate the dependence of these polarization states on solar and observation geometry at 1500nm because multiple scattering is generally a mechanism for depolarization and the ice crystals are relatively absorptive at this wavelength. Using 1500nm thus results in a higher number of reflected photons undergoing fewer scattering events, increasing the likelihood of reflected light having higher degrees of polarization. In evaluating the validity of the model, we find agreement with previous studies pertaining to near-infrared spectral directional hemispherical reflectance (i.e. black-sky albedo) and similarities in measured bidirectional reflectance factors, but few studies exist modeling polarization states of reflected light from snow surfaces. Here, we present novel results pertaining to calculated polarization states and compare dependences on solar and observation geometry for different idealized snow surfaces. If these dependencies are consistent across different ice particle shapes and sizes, then these findings could inform the SGSP algorithm by providing useful relationships between measurable physical quantities and solar and observation geometry to better understand variations in snow surface normals from remote sensing observations.

  13. Exploration of a Polarized Surface Bidirectional Reflectance Model Using the Ground-Based Multiangle SpectroPolarimetric Imager

    Directory of Open Access Journals (Sweden)

    David J. Diner

    2012-12-01

    Full Text Available Accurate characterization of surface reflection is essential for retrieval of aerosols using downward-looking remote sensors. In this paper, observations from the Ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI are used to evaluate a surface polarized bidirectional reflectance distribution function (PBRDF model. GroundMSPI is an eight-band spectropolarimetric camera mounted on a rotating gimbal to acquire pushbroom imagery of outdoor landscapes. The camera uses a very accurate photoelastic-modulator-based polarimetric imaging technique to acquire Stokes vector measurements in three of the instrument’s bands (470, 660, and 865 nm. A description of the instrument is presented, and observations of selected targets within a scene acquired on 6 January 2010 are analyzed. Data collected during the course of the day as the Sun moved across the sky provided a range of illumination geometries that facilitated evaluation of the surface model, which is comprised of a volumetric reflection term represented by the modified Rahman-Pinty-Verstraete function plus a specular reflection term generated by a randomly oriented array of Fresnel-reflecting microfacets. While the model is fairly successful in predicting the polarized reflection from two grass targets in the scene, it does a poorer job for two manmade targets (a parking lot and a truck roof, possibly due to their greater degree of geometric organization. Several empirical adjustments to the model are explored and lead to improved fits to the data. For all targets, the data support the notion of spectral invariance in the angular shape of the unpolarized and polarized surface reflection. As noted by others, this behavior provides valuable constraints on the aerosol retrieval problem, and highlights the importance of multiangle observations.

  14. Non-invasive identification of metal-oxalate complexes on polychrome artwork surfaces by reflection mid-infrared spectroscopy.

    Science.gov (United States)

    Monico, Letizia; Rosi, Francesca; Miliani, Costanza; Daveri, Alessia; Brunetti, Brunetto G

    2013-12-01

    In this work a reflection mid-infrared spectroscopy study of twelve metal-oxalate complexes, of interest in art conservation science as alteration compounds, was performed. Spectra of the reference materials highlighted the presence of derivative-like and/or inverted features for the fundamental vibrational modes as result of the main contribution from the surface component of the reflected light. In order to provide insights in the interpretation of theses spectral distortions, reflection spectra were compared with conventional transmission ones. The Kramers-Kronig (KK) algorithm, employed to correct for the surface reflection distortions, worked properly only for the derivative-like bands. Therefore, to pay attention to the use of this algorithm when interpreting the reflection spectra is recommended. The outcome of this investigation was exploited to discriminate among different oxalates on thirteen polychrome artworks analyzed in situ by reflection mid-infrared spectroscopy. The visualization of the νs(CO) modes (1400-1200 cm(-1)) and low wavenumber bands (below 900 cm(-1)) in the raw reflection profiles allowed Ca, Cu and Zn oxalates to be identified. Further information about the speciation of different hydration forms of calcium oxalates were obtained by using the KK transform. The work proves reflection mid-infrared spectroscopy to be a reliable and sensitive spectro-analytical method for identifying and mapping different metal-oxalate alteration compounds on the surface of artworks, thus providing conservation scientists with a non-invasive tool to obtain information on the state of conservation and causes of alteration of artworks. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. An attenuated total reflectance IR study of silicic acid adsorbed onto a ferric oxyhydroxide surface

    Science.gov (United States)

    Swedlund, Peter J.; Miskelly, Gordon M.; McQuillan, A. James

    2009-07-01

    Silicic acid (H 4SiO 4) can have significant effects on the properties of iron oxide surfaces in both natural and engineered aquatic systems. Understanding the reactions of H 4SiO 4 on these surfaces is therefore necessary to describe the aquatic chemistry of iron oxides and the elements that associate with them. This investigation uses attenuated total reflectance infrared spectroscopy (ATR-IR) to study silicic acid in aqueous solution and the products formed when silicic acid adsorbs onto the surface of a ferrihydrite film in 0.01 M NaCl at pH 4. A spectrum of 1.66 mM H 4SiO 4 at pH 4 (0.01 M NaCl) has an asymmetric Si-O stretch at 939 cm -1 and a weak Si-O-H deformation at 1090 cm -1. ATR-IR spectra were measured over time (for up to 7 days) for a ferrihydrite film (≈1 mg) approaching equilibrium with H 4SiO 4 at concentrations between 0.044 and 0.91 mM. Adsorbed H 4SiO 4 had a broad spectral feature between 750 and 1200 cm -1 but the shape of the spectra changed as the amount of H 4SiO 4 adsorbed on the ferrihydrite increased. When the solid phase Si/Fe mole ratio was less than ≈0.01 the ATR-IR spectra had a maximum intensity at 943 cm -1 and the spectral shape suggests that a monomeric silicate species was formed via a bidentate linkage. As the solid phase Si/Fe mole ratio increased to higher values a discrete oligomeric silicate species was formed which had maximum intensity in the ATR-IR spectra at 1001 cm -1. The spectrum of this species suggests that it is larger than a dimer and it was tentatively identified as a cyclic tetramer. A small amount of a polymeric silica phase with a broad spectral feature centered at ≈1110 cm -1 was also observed at high surface coverage. The surface composition was estimated from the relative contribution of each species to the area of the ATR-IR spectra using multivariate curve resolution with alternating least squares. For a ferrihydrite film approaching equilibrium with 0.044, 0.14, 0.40 and 0.91 mM H 4SiO 4 the

  16. Ultraviolet (UV)-reflective paint with ultraviolet germicidal irradiation (UVGI) improves decontamination of nosocomial bacteria on hospital room surfaces.

    Science.gov (United States)

    Jelden, Katelyn C; Gibbs, Shawn G; Smith, Philip W; Hewlett, Angela L; Iwen, Peter C; Schmid, Kendra K; Lowe, John J

    2017-06-01

    An ultraviolet germicidal irradiation (UVGI) generator (the TORCH, ClorDiSys Solutions, Inc.) was used to compare the disinfection of surface coupons (plastic from a bedrail, stainless steel, and chrome-plated light switch cover) in a hospital room with walls coated with ultraviolet (UV)-reflective paint (Lumacept) or standard paint. Each surface coupon was inoculated with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus faecalis (VRE), placed at 6 different sites within a hospital room coated with UV-reflective paint or standard paint, and treated by 10 min UVC exposure (UVC dose of 0-688 mJ/cm 2 between sites with standard paint and 0-553 mJ/cm 2 with UV-reflective paint) in 8 total trials. Aggregated MRSA concentrations on plastic bedrail surface coupons were reduced on average by 3.0 log 10 (1.8 log 10 Geometric Standard Deviation [GSD]) with standard paint and 4.3 log 10 (1.3 log 10 GSD) with UV-reflective paint (p = 0.0005) with no significant reduction differences between paints on stainless steel and chrome. Average VRE concentrations were reduced by ≥4.9 log 10 (light, MRSA concentrations on average were reduced by 5.2 log 10 (1.4 log 10 GSD) with standard paint and 5.1 log 10 (1.2 log 10 GSD) with UV-reflective paint (p = 0.017) and VRE by 4.4 log 10 (1.4 log 10 GSD) with standard paint and 5.3 log 10 (1.1 log 10 GSD) with UV-reflective paint (p bacteria on various surfaces compared to standard paint, particularly at a surface placement site indirectly exposed to UVC light.

  17. Synchrotron Radiation Total Reflection X-ray Fluorescence Spectroscopy for Microcontamination Analysis on Silicon Wafer Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Takaura, Norikatsu

    1997-10-01

    As dimensions in state-of-the-art CMOS devices shrink to less than 0.1 pm, even low levels of impurities on wafer surfaces can cause device degradation. Conventionally, metal contamination on wafer surfaces is measured using Total Reflection X-Ray Fluorescence Spectroscopy (TXRF). However, commercially available TXRF systems do not have the necessary sensitivity for measuring the lower levels of contamination required to develop new CMOS technologies. In an attempt to improve the sensitivity of TXRF, this research investigates Synchrotron Radiation TXRF (SR TXRF). The advantages of SR TXRF over conventional TXRF are higher incident photon flux, energy tunability, and linear polarization. We made use of these advantages to develop an optimized SR TXRF system at the Stanford Synchrotron Radiation Laboratory (SSRL). The results of measurements show that the Minimum Detection Limits (MDLs) of SR TXRF for 3-d transition metals are typically at a level-of 3x10{sup 8} atoms/cm{sup 2}, which is better than conventional TXRF by about a factor of 20. However, to use our SR TXRF system for practical applications, it was necessary to modify a commercially available Si (Li) detector which generates parasitic fluorescence signals. With the modified detector, we could achieve true MDLs of 3x10{sup 8} atoms/cm{sup 2} for 3-d transition metals. In addition, the analysis of Al on Si wafers is described. Al analysis is difficult because strong Si signals overlap the Al signals. In this work, the Si signals are greatly reduced by tuning the incident beam energy below the Si K edge. The results of our measurements show that the sensitivity for Al is limited by x-ray Raman scattering. Furthermore, we show the results of theoretical modeling of SR TXRF backgrounds consisting of the bremsstrahlung generated by photoelectrons, Compton scattering, and Raman scattering. To model these backgrounds, we extended conventional theoretical models by taking into account several aspects particular

  18. Absolute radiometric calibration of Landsat using a pseudo invariant calibration site

    Science.gov (United States)

    Helder, D.; Thome, K.J.; Mishra, N.; Chander, G.; Xiong, Xiaoxiong; Angal, A.; Choi, Tae-young

    2013-01-01

    Pseudo invariant calibration sites (PICS) have been used for on-orbit radiometric trending of optical satellite systems for more than 15 years. This approach to vicarious calibration has demonstrated a high degree of reliability and repeatability at the level of 1-3% depending on the site, spectral channel, and imaging geometries. A variety of sensors have used this approach for trending because it is broadly applicable and easy to implement. Models to describe the surface reflectance properties, as well as the intervening atmosphere have also been developed to improve the precision of the method. However, one limiting factor of using PICS is that an absolute calibration capability has not yet been fully developed. Because of this, PICS are primarily limited to providing only long term trending information for individual sensors or cross-calibration opportunities between two sensors. This paper builds an argument that PICS can be used more extensively for absolute calibration. To illustrate this, a simple empirical model is developed for the well-known Libya 4 PICS based on observations by Terra MODIS and EO-1 Hyperion. The model is validated by comparing model predicted top-of-atmosphere reflectance values to actual measurements made by the Landsat ETM+ sensor reflective bands. Following this, an outline is presented to develop a more comprehensive and accurate PICS absolute calibration model that can be Système international d'unités (SI) traceable. These initial concepts suggest that absolute calibration using PICS is possible on a broad scale and can lead to improved on-orbit calibration capabilities for optical satellite sensors.

  19. Measurements of reflectance spectra of ion-bombarded ice and application to surfaces in the outer Solar System

    International Nuclear Information System (INIS)

    O'Shaughnessy, D.J.; Boring, J.W.; Johnson, R.E.

    1988-01-01

    A number of the icy satellites of the outer planets exhibit interesting hemispherical differences in brightness which have been attributed to enhanced bombardment by the local plasma of one hemisphere. The plasma bombardment is thought to erode the icy surfaces and implant species, thereby altering the surface reflectance spectra, as well as producing fresh plasma. Here we present the first results of laboratory measurements of the wavelength dependence of the alteration of the visible reflectance spectra of H 2 O ice irradiated by keV ions. When the implanted species is chemically neutral, absorption is slightly enhanced below 0.55 μm. For an incident species containing sulphur, a strong absorption feature is produced at 0.4 μm corresponding (probably) to S 3 . This occurs at too large a wavelength to account for the absorption feature observed at Europa by Voyager and therefore casts doubt on the recent interpretations of the reflectance data of Europa. (author)

  20. The Next Generation Virgo Cluster Survey (NGVS). XVIII. Measurement and Calibration of Surface Brightness Fluctuation Distances for Bright Galaxies in Virgo (and Beyond)

    Science.gov (United States)

    Cantiello, Michele; Blakeslee, John P.; Ferrarese, Laura; Côté, Patrick; Roediger, Joel C.; Raimondo, Gabriella; Peng, Eric W.; Gwyn, Stephen; Durrell, Patrick R.; Cuillandre, Jean-Charles

    2018-04-01

    We describe a program to measure surface brightness fluctuation (SBF) distances to galaxies observed in the Next Generation Virgo Cluster Survey (NGVS), a photometric imaging survey covering 104 deg2 of the Virgo cluster in the u*, g, i, and z bandpasses with the Canada–France–Hawaii Telescope. We describe the selection of the sample galaxies, the procedures for measuring the apparent i-band SBF magnitude {\\overline{m}}i, and the calibration of the absolute Mibar as a function of observed stellar population properties. The multiband NGVS data set provides multiple options for calibrating the SBF distances, and we explore various calibrations involving individual color indices as well as combinations of two different colors. Within the color range of the present sample, the two-color calibrations do not significantly improve the scatter with respect to wide-baseline, single-color calibrations involving u*. We adopt the ({u}* -z) calibration as a reference for the present galaxy sample, with an observed scatter of 0.11 mag. For a few cases that lack good u* photometry, we use an alternative relation based on a combination of (g-i) and (g-z) colors, with only a slightly larger observed scatter of 0.12 mag. The agreement of our measurements with the best existing distance estimates provides confidence that our measurements are accurate. We present a preliminary catalog of distances for 89 galaxies brighter than B T ≈ 13.0 mag within the survey footprint, including members of the background M and W Clouds at roughly twice the distance of the main body of the Virgo cluster. The extension of the present work to fainter and bluer galaxies is in progress.

  1. MODIS/Aqua L2 Surface Reflectance, 5-Min Swath 250m, 500m, and 1km

    Data.gov (United States)

    National Aeronautics and Space Administration — MODIS/Aqua L2 Surface Reflectance, 5-Min Swath 250m, 500m, and 1km (MYD09). This product is computed from the MODIS Level 1B land bands 1, 2, 3, 4, 5, 6, and 7...

  2. MODIS/Aqua Near Real Time (NRT) Surface Reflectance Daily L2G Global 500m SIN Grid

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS Near Real Time (NRT) Surface Reflectance Daily L2G Global 500m SIN Grid product, MYD09GHK, is a seven-band product computed from the MODIS Level 1B land...

  3. Fluorine-containing composition for forming anti-reflection film on resist surface and pattern formation method

    Science.gov (United States)

    Nishi, Mineo; Makishima, Hideo

    1996-01-01

    A composition for forming anti-reflection film on resist surface which comprises an aqueous solution of a water soluble fluorine compound, and a pattern formation method which comprises the steps of coating a photoresist composition on a substrate; coating the above-mentioned composition for forming anti-reflection film; exposing the coated film to form a specific pattern; and developing the photoresist, are provided. Since the composition for forming anti-reflection film can be coated on the photoresist in the form of an aqueous solution, not only the anti-reflection film can be formed easily, but also, the film can be removed easily by rinsing with water or alkali development. Therefore, by the pattern formation method according to the present invention, it is possible to form a pattern easily with a high dimensional accuracy.

  4. Analysis of various quality attributes of sunflower and soybean plants by near infra-red reflectance spectroscopy: Development and validation calibration models

    Science.gov (United States)

    Sunflower and soybean are summer annuals that can be grown as an alternative to corn and may be particularly useful in organic production systems. Rapid and low cost methods of analyzing plant quality would be helpful for crop management. We developed and validated calibration models for Near-infrar...

  5. Auto-calibrated scanning-angle prism-type total internal reflection microscopy for nanometer-precision axial position determination and optional variable-illumination-depth pseudo total internal reflection microscopy

    Science.gov (United States)

    Fang, Ning; Sun, Wei

    2015-04-21

    A method, apparatus, and system for improved VA-TIRFM microscopy. The method comprises automatically controlled calibration of one or more laser sources by precise control of presentation of each laser relative a sample for small incremental changes of incident angle over a range of critical TIR angles. The calibration then allows precise scanning of the sample for any of those calibrated angles for higher and more accurate resolution, and better reconstruction of the scans for super resolution reconstruction of the sample. Optionally the system can be controlled for incident angles of the excitation laser at sub-critical angles for pseudo TIRFM. Optionally both above-critical angle and sub critical angle measurements can be accomplished with the same system.

  6. Inverse Kinematics and Model Calibration Optimization of a Five-D.O.F. Robot for Repairing the Surface Profiles of Hydraulic Turbine Blades

    Directory of Open Access Journals (Sweden)

    Jose Mauricio S.T. Motta

    2016-06-01

    Full Text Available This paper presents and discusses the results of an ongoing R&D project aiming to design and build a fully automated prototype of a specialized spherical robotic welding system for repairing hydraulic turbine surfaces eroded by cavitation pitting and/or cracks produced by cyclic loading. The system has an embedded vision sensor built to acquire range images by laser scanning over the blade's surface and produce 3D models to locate the damaged spots to be registered in a 3D coordinate system into the robot controller, enabling the robot to repair the flaws automatically by welding in layers. The paper is focused on the robot kinematic model and describes an iterative algorithm to process the inverse kinematics with only five degrees-of-freedom. The algorithm makes use of data collected from a vision sensor to ensure that the welding gun axis is perpendicular to the blade's surface. Besides this, it proposes a modelling and optimization mathematical routine for more efficient robot calibration, which can be used with any type of robot. This robot calibration optimization scheme finds the optimal error parameter vector based on the condition number of the manipulator transformation composed from the partial derivatives of the error parameters. Experimental results proved both the iterative algorithm to perform the inverse kinematics and the technique to optimize robot calibration to be very efficient.

  7. A Framework for Estimating the 30 m Thermal-Infrared Broadband Emissivity From Landsat Surface Reflectance Data

    Science.gov (United States)

    Cheng, Jie; Liu, Hao; Liang, Shunlin; Nie, Aixiu; Liu, Qiang; Guo, Yamin

    2017-11-01

    The land surface thermal-infrared broadband emissivity (BBE) is a vital variable for estimating land surface radiation budgets (SRBs). We develop a framework for retrieving the 30 m BBE from Landsat surface reflectance data to estimate SRBs at finer scales and validate coarse resolution data. In the developed framework, the land surface is classified as bare soils and vegetated surfaces to allow different algorithms to be used for the BBE estimation. We propose a downscaling algorithm that uses the empirical relationship between the Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) BBE and Landsat surface reflectance at 90 m to retrieve the 30 m BBE over bare soils. A look-up table (LUT)-based algorithm is proposed for vegetated surfaces. The BBE is interpolated from a LUT that is constructed from the 4SAIL radiative transfer model with inputs of the leaf BBE, the soil background BBE, and the leaf area index (LAI). Ground measurements that were collected at 11 relatively homogeneous sandy sites during three independent field campaigns are used to validate the proposed algorithm over bare soils. The average difference between the retrieved and field-measured BBEs is 0.012. We produce the land surface BBE of China in 2008 by using the developed framework and composited winter and summer seasonal BBE maps. The composited seasonal BBE maps are compared to the seasonal BBE maps derived from the ASTER emissivity product. The bias is within ±0.005 over bare soils and ranges from 0.012 to 0.019 over vegetated surfaces. Combined with the validated results in this study and published references, the comparison results demonstrate the good performance of the developed framework. This study provides a new perspective on estimating BBEs from sensors with only a thermal-infrared channel.

  8. Building and calibrating a large-extent and high resolution coupled groundwater-land surface model using globally available data-sets

    Science.gov (United States)

    Sutanudjaja, E. H.; Van Beek, L. P.; de Jong, S. M.; van Geer, F.; Bierkens, M. F.

    2012-12-01

    The current generation of large-scale hydrological models generally lacks a groundwater model component simulating lateral groundwater flow. Large-scale groundwater models are rare due to a lack of hydro-geological data required for their parameterization and a lack of groundwater head data required for their calibration. In this study, we propose an approach to develop a large-extent fully-coupled land surface-groundwater model by using globally available datasets and calibrate it using a combination of discharge observations and remotely-sensed soil moisture data. The underlying objective is to devise a collection of methods that enables one to build and parameterize large-scale groundwater models in data-poor regions. The model used, PCR-GLOBWB-MOD, has a spatial resolution of 1 km x 1 km and operates on a daily basis. It consists of a single-layer MODFLOW groundwater model that is dynamically coupled to the PCR-GLOBWB land surface model. This fully-coupled model accommodates two-way interactions between surface water levels and groundwater head dynamics, as well as between upper soil moisture states and groundwater levels, including a capillary rise mechanism to sustain upper soil storage and thus to fulfill high evaporation demands (during dry conditions). As a test bed, we used the Rhine-Meuse basin, where more than 4000 groundwater head time series have been collected for validation purposes. The model was parameterized using globally available data-sets on surface elevation, drainage direction, land-cover, soil and lithology. Next, the model was calibrated using a brute force approach and massive parallel computing, i.e. by running the coupled groundwater-land surface model for more than 3000 different parameter sets. Here, we varied minimal soil moisture storage and saturated conductivities of the soil layers as well as aquifer transmissivities. Using different regularization strategies and calibration criteria we compared three calibration scenarios

  9. Broadband infrared reflective surfaces using doped and stacked polar dielectric layers

    Science.gov (United States)

    Janipour, Mohsen; Sendur, Kursat

    2018-02-01

    Polar dielectrics, such as SiC, are excellent candidates for operation in extreme environments due to their excellent mechanical and thermal properties. In addition, they can achieve good IR reflection in the Reststrahlen band. However, these materials have relatively narrow spectral bandwidth for reflection, especially considering that the broadband illumination sources in extreme environments. In this study, we investigated the broadband reflection properties of polar dielectrics by engineering the Reststrahlen band through doping and stacked layers. Our results indicate that by doping polar dielectrics, spectral reflection bandwidth can be significantly broadened. In addition, we demonstrate that by stacking different polar dielectric layers, the reflection spectrum of different materials can be overlapped, and thereby, significantly broader spectrum is obtained.

  10. Study on the effect of ambient gas on nanostructure formation on metal surfaces during femtosecond laser ablation for fabrication of low-reflective surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Smausz, Tomi, E-mail: tomi@physx.u-szeged.hu [MTA-SZTE Research Group on Photoacoustic Spectroscopy, University of Szeged, 6720 Szeged, Dóm tér 9 (Hungary); Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Csizmadia, Tamás [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Attosecond Light Pulse Source, ELI-Hu Nkft, H-6720 Szeged, Dugonics ter 13 (Hungary); Tápai, Csaba; Kopniczky, Judit [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Oszkó, Albert [Department of Physical Chemistry and Material Science, University of Szeged, H-6720 Szeged, Aradi vértanuk tere 1 (Hungary); Ehrhardt, Martin; Lorenz, Pierre; Zimmer, Klaus; Prager, Andrea [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Hopp, Béla [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary)

    2016-12-15

    Highlights: • Metal surfaces were irradiated with femtosecond laser in different gas environments. • The reflectivity, morphology and chemical composition of the surfaces were studied. • Darkening was influenced by chemical and physical interaction of the plume and gas. • Molecular mass of the applied gas had an impact on the nanostructure formation. • For some of the used metals the oxide formation affected the reflective properties. - Abstract: Nanostructure formation on bulk metals (silver, gold, copper and titanium) by femtosecond Ti-sapphire laser irradiation (775 nm, 150 fs) is studied aiming the production of low-reflectivity surfaces and the better understanding of the development process. The experiments were performed in nitrogen, air, oxygen and helium environments at atmospheric pressure. The samples were irradiated with fluences in the 0.1–2 J/cm{sup 2} range and an average pulse number of 100 falling over a given area. The reflectivity of the treated surfaces was determined by a microspectrometer in the 450–800 nm range and their morphology was studied by scanning electron microscopy. The gas ambience influenced the results via two effects: formation processes and the chemically-induced modifications of the nanostructures. In case of He the nanoparticle aggregates–otherwise generally present–are predominantly missing, which leads to a lower darkening efficiency. The presence of oxygen enhances the darkening effect for copper mostly at lower fluences, while causes a slow increase in reflectivity in the case of titanium (in case of pure oxygen) in the high fluence range. The surface morphology in case of nitrogen and air were quite similar probably due to their close molecular mass values.

  11. Principal component analysis for surface reflection components and structure in facial images and synthesis of facial images for various ages

    Science.gov (United States)

    Hirose, Misa; Toyota, Saori; Ojima, Nobutoshi; Ogawa-Ochiai, Keiko; Tsumura, Norimichi

    2017-08-01

    In this paper, principal component analysis is applied to the distribution of pigmentation, surface reflectance, and landmarks in whole facial images to obtain feature values. The relationship between the obtained feature vectors and the age of the face is then estimated by multiple regression analysis so that facial images can be modulated for woman aged 10-70. In a previous study, we analyzed only the distribution of pigmentation, and the reproduced images appeared to be younger than the apparent age of the initial images. We believe that this happened because we did not modulate the facial structures and detailed surfaces, such as wrinkles. By considering landmarks and surface reflectance over the entire face, we were able to analyze the variation in the distributions of facial structures and fine asperity, and pigmentation. As a result, our method is able to appropriately modulate the appearance of a face so that it appears to be the correct age.

  12. Prospects of using Bayesian model averaging for the calibration of one-month forecasts of surface air temperature over South Korea

    Science.gov (United States)

    Kim, Chansoo; Suh, Myoung-Seok

    2013-05-01

    In this study, we investigated the prospect of calibrating probabilistic forecasts of surface air temperature (SAT) over South Korea by using Bayesian model averaging (BMA). We used 63 months of simulation results from four regional climate models (RCMs) with two boundary conditions (NCEP-DOE and ERA-interim) over the CORDEX East Asia. Rank histograms and residual quantile-quantile (R-Q-Q) plots showed that the simulation skills of the RCMs differ according to season and geographic location, but the RCMs show a systematic cold bias irrespective of season and geographic location. As a result, the BMA weights are clearly dependent on geographic location, season, and correlations among the models. The one-month equal weighted ensemble (EWE) outputs for the 59 stations over South Korea were calibrated using the BMA method for 48 monthly time periods based on BMA weights obtained from the previous 15 months of training data. The predictive density function was calibrated using BMA and the individual forecasts were weighted according to their performance. The raw ensemble forecasts were assessed using the flatness of the rank histogram and the R-Q-Q plot. The results showed that BMA improves the calibration of the EWE and the other weighted ensemble forecasts irrespective of season, simulation skill of the RCM, and geographic location. In addition, deterministic-style BMA forecasts usually perform better than the deterministic forecast of the single best member.

  13. Calibration assembly for nuclear reactor vessel inspection apparatus

    International Nuclear Information System (INIS)

    Elsner, H.J.

    1981-01-01

    A removable calibration assembly can be utilized to verify the angular mounting of transducers in an array employed in an ultrasonic inpsection apparatus, to calibrate one axis of movement of the array with reference to a starting point, or to measure and calibrate the speed per unit of distance of the transducer's ultrasonic beam in the operating medium. The calibration assembly includes both a large and small reflecting surface separated by known distances, and several large cones, the tips of which are machined or adjusted to angles at which certain of the transducers are to be mounted. Clamping means for securing the calibration assembly to the inspection apparatus at a predetermined orientation is provided

  14. Collimated light reflection and transmission of a surface partially covered by large and tenuous particles.

    Science.gov (United States)

    Vázquez-Estrada, Omar; García-Valenzuela, Augusto

    2016-11-01

    We derive simple approximate expressions for the reflectivity and transmissivity of light from disordered monolayers of tenuous particles of dimensions larger than the wavelength and supported by a flat interface. The expressions derived can be used for different particle shapes and for moderate angles of incidence. We then investigate the effects of particle shape and orientation on reflectivity and transmissivity spectra of a monolayer of tenuous particles containing an optical chromophore in a solution in their interior. We also simulate the effects of a particle's shape and orientation on the angle dependence of the optical reflectivity and transmissivity. In our examples, we consider disordered monolayers of particles analogous to some biological cells.

  15. Online Resource for Earth-Observing Satellite Sensor Calibration

    Science.gov (United States)

    McCorkel, J.; Czapla-Myers, J.; Thome, K.; Wenny, B.

    2015-01-01

    The Radiometric Calibration Test Site (RadCaTS) at Railroad Valley Playa, Nevada is being developed by the University of Arizona to enable improved accuracy and consistency for airborne and satellite sensor calibration. Primary instrumentation at the site consists of ground-viewing radiometers, a sun photometer, and a meteorological station. Measurements made by these instruments are used to calculate surface reflectance, atmospheric properties and a prediction for top-of-atmosphere reflectance and radiance. This work will leverage research for RadCaTS, and describe the requirements for an online database, associated data formats and quality control, and processing levels.

  16. Surface-atmosphere interactions with coupled within-canopy aerodynamic resistance and canopy reflection.

    Science.gov (United States)

    Timmermans, J.; van der Tol, C.; Verhoef, W.; Su, Z.

    2009-04-01

    Models that describe the exchange of CO2 and H2O between the surface and atmosphere use bulk-parametrization of the within-canopy aerodynamic resistance and leaf area density (eq. LAI). This bulk parametrization is based on the Monin-Obukhov Similarity (MOS) theory. The MOS theory however breaks down for sparse canopies and it cannot couple profiles in the leaf density to profiles in the within-canopy aerodynamic resistance. The objective of this research is to create a simple model that is able to couple the within-canopy aerodynamic resistance and canopy reflection for different levels in the canopy. This model should be able to represent the canopy using as fewer parameters as possible, in order to facilitate inversion of remote sensing imagery. A virtual canopy was simulated using an L-systems approach, Lindenmayer 1968. The L-system approach was chosen because it describes the canopy with fractals. It therefore needs very little inputs to simulate a virtual canopy. A vertical profile of leaf density was calculated for 60 levels from this virtual canopy. The within-canopy aerodynamic resistance was modeled from the vertical leaf density profile using foliage drag coefficient, Massman 1997. A modified version of the SCOPE (Soil Canopy Observations and Photosynthesis) model was used to calculate the H2O and CO2 fluxes using the vertical profiles of leaf density and within-canopy aerodynamic resistance. The simulated fluxes are compared with field measurements over a vineyard and a forested area. The field measurements in both areas are acquired using the same setup: a basic flux tower in addition with an eddy-covariance setup. We present in this article the methodology and the results, as a proof of concept. references Massman, W.J., An Analytical One-Dimensional Model of Momentum Transfer by vegetation of arbitrary structure, Boundary-Layer Meteorology, 1997, 83, 407-421 Lindenmayer, A., Mathematical Models for Cellular Interactions in Development, Journal of

  17. Native SrTiO3 (001) surface layer from resonant Ti L2,3 reflectance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Valvidares, Manuel; Huijben, Mark; Yu, Pu; Ramesh, Ramamoorthy; Kortright, Jeffrey

    2010-11-03

    We quantitatively model resonant Ti L2,3 reflectivity Rs,p(q, hn) from several SrTiO3 (001) single crystals having different initial surface preparations and stored in ambient conditions before and between measurements. All samples exhibit unexpected 300 K Rs(hn) - Rp(hn) anisotropy corresponding to weak linear dichroism and tetragonal distortion of the TiO6 octahedra indicating a surface layer with properties different from cubic SrTiO3. Oscillations in Rs(q) confirm a ubiquitous surface layer 2-3 nm thick that evolves over a range of time scales. Resonant optical constant spectra derived from Rs,p(hn) assuming a uniform sample are refined using a single surface layer to fit measured Rs(q). Differences in surface layer and bulk optical properties indicate that the surface is significantly depleted in Sr and enriched in Ti and O. While consistent with the tendency of SrTiO3 surfaces toward non-stoichiometry, this layer does not conform simply to existing models for the near surface region and apparently forms via room temperature surface reactions with the ambient. This new quantitative spectral modeling approach is generally applicable and has potential to study near-surface properties of a variety of systems with unique chemical and electronic sensitivities.

  18. 3D reconstruction of a patient-specific surface model of the proximal femur from calibrated x-ray radiographs: A validation study

    International Nuclear Information System (INIS)

    Zheng Guoyan; Schumann, Steffen

    2009-01-01

    Twenty-three femurs (one plastic bone and twenty-two cadaver bones) with both nonpathologic and pathologic cases were considered to validate a statistical shape model based technique for three-dimensional (3D) reconstruction of a patient-specific surface model from calibrated x-ray radiographs. The 3D reconstruction technique is based on an iterative nonrigid registration of the features extracted from a statistically instantiated 3D surface model to those interactively identified from the radiographs. The surface models reconstructed from the radiographs were compared to the associated ground truths derived either from a 3D CT-scan reconstruction method or from a 3D laser-scan reconstruction method and an average error distance of 0.95 mm were found. Compared to the existing works, our approach has the advantage of seamlessly handling both nonpathologic and pathologic cases even when the statistical shape model that we used was constructed from surface models of nonpathologic bones.

  19. Kaguya observations of the lunar wake in the terrestrial foreshock: Surface potential change by bow-shock reflected ions

    Science.gov (United States)

    Nishino, Masaki N.; Harada, Yuki; Saito, Yoshifumi; Tsunakawa, Hideo; Takahashi, Futoshi; Yokota, Shoichiro; Matsushima, Masaki; Shibuya, Hidetoshi; Shimizu, Hisayoshi

    2017-09-01

    There forms a tenuous region called the wake behind the Moon in the solar wind, and plasma entry/refilling into the wake is a fundamental problem of the lunar plasma science. High-energy ions and electrons in the foreshock of the Earth's magnetosphere were detected at the lunar surface in the Apollo era, but their effects on the lunar night-side environment have never been studied. Here we show the first observation of bow-shock reflected protons by Kaguya (SELENE) spacecraft in orbit around the Moon, confirming that solar wind plasma reflected at the terrestrial bow shock can easily access the deepest lunar wake when the Moon stays in the foreshock (We name this mechanism 'type-3 entry'). In a continuous type-3 event, low-energy electron beams from the lunar night-side surface are not obvious even though the spacecraft location is magnetically connected to the lunar surface. On the other hand, in an intermittent type-3 entry event, the kinetic energy of upward-going field-aligned electron beams decreases from ∼ 80 eV to ∼ 20 eV or electron beams disappear as the bow-shock reflected ions come accompanied by enhanced downward electrons. According to theoretical treatment based on electric current balance at the lunar surface including secondary electron emission by incident electron and ion impact, we deduce that incident ions would be accompanied by a few to several times higher flux of an incident electron flux, which well fits observed downward fluxes. We conclude that impact by the bow-shock reflected ions and electrons raises the electrostatic potential of the lunar night-side surface.

  20. Absolute Radiometric Calibration of KOMPSAT-3A

    Directory of Open Access Journals (Sweden)

    H. Y. Ahn

    2016-06-01

    Full Text Available This paper presents a vicarious radiometric calibration of the Korea Multi-Purpose Satellite-3A (KOMPSAT-3A performed by the Korea Aerospace Research Institute (KARI and the Pukyong National University Remote Sensing Group (PKNU RSG in 2015.The primary stages of this study are summarized as follows: (1 A field campaign to determine radiometric calibrated target fields was undertaken in Mongolia and South Korea. Surface reflectance data obtained in the campaign were input to a radiative transfer code that predicted at-sensor radiance. Through this process, equations and parameters were derived for the KOMPSAT-3A sensor to enable the conversion of calibrated DN to physical units, such as at-sensor radiance or TOA reflectance. (2 To validate the absolute calibration coefficients for the KOMPSAT-3A sensor, we performed a radiometric validation with a comparison of KOMPSAT-3A and Landsat-8 TOA reflectance using one of the six PICS (Libya 4. Correlations between top-of-atmosphere (TOA radiances and the spectral band responses of the KOMPSAT-3A sensors at the Zuunmod, Mongolia and Goheung, South Korea sites were significant for multispectral bands. The average difference in TOA reflectance between KOMPSAT-3A and Landsat-8 image over the Libya 4, Libya site in the red-green-blue (RGB region was under 3%, whereas in the NIR band, the TOA reflectance of KOMPSAT-3A was lower than the that of Landsat-8 due to the difference in the band passes of two sensors. The KOMPSAT-3Aensor includes a band pass near 940 nm that can be strongly absorbed by water vapor and therefore displayed low reflectance. Toovercome this, we need to undertake a detailed analysis using rescale methods, such as the spectral bandwidth adjustment factor.

  1. Calibration uncertainty

    DEFF Research Database (Denmark)

    Heydorn, Kaj; Anglov, Thomas

    2002-01-01

    Methods recommended by the International Standardization Organisation and Eurachem are not satisfactory for the correct estimation of calibration uncertainty. A novel approach is introduced and tested on actual calibration data for the determination of Pb by ICP-AES. The improved calibration...

  2. Stretched membrane heliostats: design and structural analysis of reflectance module and support of a heliostats of 9 m. diaform and 60 m''3 of reflectance surface

    International Nuclear Information System (INIS)

    Figarola Torres, J. M.

    1993-01-01

    After having designed and built at CIEMAT a first prototype of a Btretched membrane heliostats of 3 m. diameter, the design and the structural analysis of the different components included in the reflectance module and support of another heliostats, this one of 9 m. diameter and 60 m2. of reflectance surface, are shown In this report. This last heliostats will be mounted on a pedestal and its driving device at the Solar Platform of Almeria. In order to optimize design and performance, the structural analysis of its basic components has been analyzed with the finite elements program ANSYS. The following elements have been subject to analysis: the membrane and their ring supports, stretching system and the structural support. A similar scheme to the one applied to the previous prototype has been used on the focus control system. That includes a linear transducer, a variable frequency and a fan. Finally it has to be pointed out that substantial improvements have been achieved with respect to the first prototype concerning design and cost. (Author) 5 refs

  3. Investigation of surface and sub-surface damage in high quality synthetic diamonds by X-ray reflectivity and grazing incidence in-plane diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Bussone, Genziana; Lafford, Tamzin A.; Masiello, Fabio; Carbone, Gerardina; Schuelli, Tobias U.; Rommeveaux, Amparo Vivo; Haertwig, Juergen [European Synchrotron Radiation Facility, 6, Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex 9 (France); Gibaud, Alain [Laboratoire PEC, Universite du Maine le Mans, Avenue Olivier Messiaen, 72 085 Le Mans (France); Connell, Simon H. [University of Johannesburg, cnr Kingsway Ave and University Rd, Auckland Park, 2006, Johannesburg (South Africa); Wormington, Matthew [Jordan Valley Semiconductors Inc., 8601 Cross Park Drive, Suite 200, Austin, TX 78754-4578 (United States)

    2011-11-15

    High quality single-crystal synthetic diamond is the most suitable material for selected X-ray optical applications in the latest generation X-ray light sources. Excellent heat handling properties, as well as low absorption, coupled with high perfection in the crystal bulk and very good surface quality, are crucial for such applications. In recent years, some progress has been made in the fields of surface treatments and growth techniques. Conventional scaife polishing is largely ineffective on the diamond (111) surface. To overcome this disadvantage, one possibility is to use the Hot Metal polishing technique. An investigation of surface and sub-surface damage of Hot Metal polished and cleaved surfaces, has been carried out using depth-sensitive non-destructive X-ray techniques. The near surface crystalline quality was studied as a function of depth using in-plane grazing incidence X-ray diffraction. Additionally, X-ray reflectivity was used to investigate the density, thickness and roughness of near-surface layers. The measurements enable us to estimate the thickness of the affected sub-surface layer. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Analysis of bacteria on steel surfaces using reflectance micro-Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Ojeda, Jesús J; Romero-González, María E; Banwart, Steven A

    2009-08-01

    Reflectance micro-Fourier transform infrared (FT-IR) analysis has been applied to characterize biofilm formation of Aquabacterium commune, a common microorganism present on drinking water distribution systems, onto the increasingly popular pipe material stainless steel EN1.4307. The applicability of the reflectance micro-FT-IR technique for analyzing the bacterial functional groups is discussed, and the results are compared to spectra obtained using more conventional FT-IR techniques: transmission micro-FT-IR, attenuated transmitted reflectance (ATR), and KBr pellets. The differences between the infrared spectra of wet and dried bacteria, as well as free versus attached bacteria, are also discussed. The spectra obtained using reflectance micro-FT-IR spectroscopy were comparable to those obtained using other FT-IR techniques. The absence of sample preparation, the potential to analyze intact samples, and the ability to characterize opaque and thick samples without the need to transfer the bacterial samples to an infrared transparent medium or produce a pure culture were the main advantages of reflectance micro-FT-IR spectroscopy.

  5. Manual matching of perceived surface orientation is affected by arm posture–Evidence of calibration between proprioception and visual experience in near space

    Science.gov (United States)

    Li, Zhi; Durgin, Frank H.

    2011-01-01

    Proprioception of hand orientation (orientation production using the hand) is compared with manual matching of visual orientation (visual surface matching using the hand) in two experiments. In Experiment 1, using self-selected arm postures, the proportions of wrist and elbow flexion spontaneously used to orient the pitch of the hand (20% and 80% respectively) are relatively similar across both manual matching tasks and manual orientation production tasks for most participants. Proprioceptive error closely matched perceptual biases previously reported for visual orientation perception, suggesting calibration of proprioception to visual biases. A minority of participants, who attempted to use primarily wrist flexion while holding the forearm horizontal, performed poorly at the manual matching task, consistent with proprioceptive error caused by biomechanical constraints of their self-selected posture. In Experiment 2, postural choices were constrained to primarily wrist or elbow flexion without imposing biomechanical constraints (using a raised forearm). Identical relative offsets were found between the two constraint groups in manual matching and manual orientation production. The results support two claims: (1) manual orientation matching to visual surfaces is based on manual proprioception and (2) calibration between visual and proprioceptive experiences guarantees relatively accurate manual matching for surfaces within reach despite systematic visual biases in perceived surface orientation. PMID:22086494

  6. Using Flux Site Observations to Calibrate Root System Architecture Stencils for Water Uptake of Plant Functional Types in Land Surface Models.

    Science.gov (United States)

    Bouda, M.

    2017-12-01

    Root system architecture (RSA) can significantly affect plant access to water, total transpiration, as well as its partitioning by soil depth, with implications for surface heat, water, and carbon budgets. Despite recent advances in land surface model (LSM) descriptions of plant hydraulics, RSA has not been included because of its three-dimensional complexity, which makes RSA modelling generally too computationally costly. This work builds upon the recently introduced "RSA stencil," a process-based 1D layered model that captures the dynamic shifts in water potential gradients of 3D RSA in response to heterogeneous soil moisture profiles. In validations using root systems calibrated to the rooting profiles of four plant functional types (PFT) of the Community Land Model, the RSA stencil predicts plant water potentials within 2% of the outputs of full 3D models, despite its trivial computational cost. In transient simulations, the RSA stencil yields improved predictions of water uptake and soil moisture profiles compared to a 1D model based on root fraction alone. Here I show how the RSA stencil can be calibrated to time-series observations of soil moisture and transpiration to yield a water uptake PFT definition for use in terrestrial models. This model-data integration exercise aims to improve LSM predictions of soil moisture dynamics and, under water-limiting conditions, surface fluxes. These improvements can be expected to significantly impact predictions of downstream variables, including surface fluxes, climate-vegetation feedbacks and soil nutrient cycling.

  7. Reflection of sound from finite-size plane and curved surfaces

    DEFF Research Database (Denmark)

    Rindel, Jens Holger

    2005-01-01

    The author’s research on reflectors over nearly 25 years is summarized. The influence of curvature was analyzed by a geometrical model in order to quantify the attenuation by a simple expression. Reflection from a finite size plate was studied using the Kirchhoff-Fresnel approximation and the des......The author’s research on reflectors over nearly 25 years is summarized. The influence of curvature was analyzed by a geometrical model in order to quantify the attenuation by a simple expression. Reflection from a finite size plate was studied using the Kirchhoff-Fresnel approximation...... in the refurbishment of the concert hall of the Danish Radio in Copenhagen 1989, and later in many other halls. In order to describe the scattering due to edge diffraction the directional characteristic of reflections from a finite-size plate has been studied and a simple approximation valid for octave bands has been...

  8. Simulation of reflectance from white-anodised aluminium surfaces using polyurethane–TiO2 composite coatings

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Johansen, Villads Egede; Ambat, Rajan

    2015-01-01

    Theoretical calculations and experimental studies were carried out on polyurethane (PU)–TiO2 composite coatings on bright and matte aluminium surfaces with an aim to understand and tailor the light scattering from particles incorporated into an anodised layer for designing the optical appearance...... of anodised surfaces. PU matrix was selected for its matching refractive-index (n = 1.7) with anodic alumina layer. Three different TiO2 particle size distributions were dispersed in PU and spin coated onto bright high-gloss and matte caustic-etched aluminium substrates. The reflectance spectra of coated...

  9. Content uniformity determination of pharmaceutical tablets using five near-infrared reflectance spectrometers: a process analytical technology (PAT) approach using robust multivariate calibration transfer algorithms.

    Science.gov (United States)

    Sulub, Yusuf; LoBrutto, Rosario; Vivilecchia, Richard; Wabuyele, Busolo Wa

    2008-03-24

    Near-infrared calibration models were developed for the determination of content uniformity of pharmaceutical tablets containing 29.4% drug load for two dosage strengths (X and Y). Both dosage strengths have a circular geometry and the only difference is the size and weight. Strength X samples weigh approximately 425 mg with a diameter of 12 mm while strength Y samples, weigh approximately 1700 mg with a diameter of 20mm. Data used in this study were acquired from five NIR instruments manufactured by two different vendors. One of these spectrometers is a dispersive-based NIR system while the other four were Fourier transform (FT) based. The transferability of the optimized partial least-squares (PLS) calibration models developed on the primary instrument (A) located in a research facility was evaluated using spectral data acquired from secondary instruments B, C, D and E. Instruments B and E were located in the same research facility as spectrometer A while instruments C and D were located in a production facility 35 miles away. The same set of tablet samples were used to acquire spectral data from all instruments. This scenario mimics the conventional pharmaceutical technology transfer from research and development to production. Direct cross-instrument prediction without standardization was performed between the primary and each secondary instrument to evaluate the robustness of the primary instrument calibration model. For the strength Y samples, this approach was successful for data acquired on instruments B, C, and D producing root mean square error of prediction (RMSEP) of 1.05, 1.05, and 1.22%, respectively. However for instrument E data, this approach was not successful producing an RMSEP value of 3.40%. A similar deterioration was observed for the strength X samples, with RMSEP values of 2.78, 5.54, 3.40, and 5.78% corresponding to spectral data acquired on instruments B, C, D, and E, respectively. To minimize the effect of instrument variability

  10. Surface segregation of InGaAs films by the evolution of reflection high-energy electron diffraction patterns

    International Nuclear Information System (INIS)

    Zhou Xun; Luo Zi-Jiang; Guo Xiang; Zhang Bi-Chan; Shang Lin-Tao; Zhou Qing; Deng Chao-Yong; Ding Zhao

    2012-01-01

    Surface segregation is studied via the evolution of reflection high-energy electron diffraction (RHEED) patterns under different values of As 4 BEP for InGaAs films. When the As 4 BEP is set to be zero, the RHEED pattern keeps a 4×3/(n × 3) structure with increasing temperature, and surface segregation takes place until 470 °C. The RHEED pattern develops into a metal-rich (4 × 2) structure as temperature increases to 495 °C. The reason for this is that surface segregation makes the In inside the InGaAs film climb to its surface. With the temperature increasing up to 515 °C, the RHEED pattern turns into a GaAs(2 × 4) structure due to In desorption. While the As 4 BEP comes up to a specific value (1.33 × 10 -4 Pa−1.33 × 10 -3 Pa), the surface temperature can delay the segregation and desorption. We find that As 4 BEP has a big influence on surface desorption, while surface segregation is more strongly dependent on temperature than surface desorption. (condensed matter: structural, mechanical, and thermal properties)

  11. Interactions of satellite-speed helium atoms with satellite-surfaces. 1. Spatial distributions of reflected helium atoms

    International Nuclear Information System (INIS)

    Liu, S.M.; Rodgers, W.E.; Knuth, E.L.

    1975-06-01

    Interactions of satellite-speed helium atoms with practical satellite surfaces were investigated experimentally, and spatial distributions of satellite-speed helium beams scattered from four different engineering surfaces were measured. The 7000-m/s helium beams were produced using an arc-heated supersonic molecular beam source. The test surfaces included cleaned 6061-T6 aluminum plate, anodized aluminum foil, white paint, and quartz surfaces. Both in-plane (in the plane containing the incident beam and the surface normal) and out-of-plane spatial distributions of reflected helium atoms were measured for six different incidence angles (0, 15, 30, 45, 60, and 75 deg from the surface normal). It was found that a large fraction of the incident helium atoms were scattered back in the vicinity of the incoming beam, particularly in the case of glancing incidence angles. This unexpected scattering feature results perhaps from the gross roughness of these test surfaces. This prominent backscattering could yield drag coefficients which are higher than for surfaces with either forward-lobed or diffusive (cosine) scattering patterns

  12. Analysis of human perception of facial skin radiance by means of image histogram parameters of surface and subsurface reflections from the skin.

    Science.gov (United States)

    Matsubara, Akira; Liang, Zhiwu; Sato, Yuji; Uchikawa, Keiji

    2012-08-01

    The appearance of the skin is the result of complicated light-skin interactions involving surface and subsurface reflections. Radiant skin is a complicated attribute but is important for skin beauty. The aim of the present study was to achieve an understanding of the association between human perceptions of skin radiance and image histogram parameters from technically recorded images of surface and subsurface reflections. Facial images of 45 subjects were evaluated visually by 30 respondents and were also computer analyzed in terms of their image histogram parameters. A partial least squares regression model was created to explain visual perceptions in terms of the image histogram parameters. Visual perceptions of subsurface reflections can be explained in terms of the mean from the subsurface reflection image histogram, and visual perceptions of surface reflections can be explained in terms of the standard deviation (SD) and skewness from the surface reflection image histogram. Skin radiance can be explained in terms of the mean from the subsurface reflection and the SD from the surface reflection. To acquire skin radiance, a surface reflection component that makes the skin look shiny and a subsurface reflection component that is in line with skin fairness are both needed. A balance of these features provides the origin of skin radiance. © 2011 John Wiley & Sons A/S.

  13. Using optical tweezers for measuring the interaction forces between human bone cells and implant surfaces: System design and force calibration

    International Nuclear Information System (INIS)

    Andersson, Martin; Madgavkar, Ashwin; Stjerndahl, Maria; Wu, Yanrong; Tan, Weihong; Duran, Randy; Niehren, Stefan; Mustafa, Kamal; Arvidson, Kristina; Wennerberg, Ann

    2007-01-01

    Optical tweezers were used to study the interaction and attachment of human bone cells to various types of medical implant materials. Ideally, the implant should facilitate cell attachment and promote migration of the progenitor cells in order to decrease the healing time. It is therefore of interest, in a controlled manner, to be able to monitor the cell adhesion process. Results from such studies would help foresee the clinical outcome of integrating medical implants. The interactions between two primary cell culture models, human gingival fibroblasts and bone forming human osteoblast cells, and three different implant materials, glass, titanium, and hydroxyapatite, were studied. A novel type of optical tweezers, which has a newly designed quadrant detector and a powerful 3 W laser was constructed and force calibrated using two different methods: one method in which the stiffness of the optical trap was obtained by monitoring the phase lag between the trap and the moved object when imposing a forced oscillation on the trapped object and another method in which the maximum trapping force was derived from the critical velocity at which the object escapes the trap. Polystyrene beads as well as cells were utilized for the calibrations. This is the first time that cells have been used directly for these types of force calibrations and, hence, direct measurements of forces exerted on cells can be performed, thus avoiding the difficulties often encountered when translating the results obtained from cell measurements to the calibrations obtained with reference materials. This more straightforward approach represents an advantage in comparison to established methods

  14. Nonlinear reflection of a spherically divergent N-wave from a plane surface: Optical interferometry measurements in air

    Energy Technology Data Exchange (ETDEWEB)

    Karzova, M., E-mail: masha@acs366.phys.msu.ru [Laboratoire de Mécanique des Fluides et d’Acoustique, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation); Yuldashev, P.; Khokhlova, V. [Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation); Ollivier, S.; Blanc-Benon, Ph. [Laboratoire de Mécanique des Fluides et d’Acoustique, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France)

    2015-10-28

    Mach stem is a well-known structure typically observed in the process of strong (acoustic Mach numbers greater than 0.4) step-shock waves reflection from a rigid boundary. However, this phenomenon has been much less studied for weak shocks in nonlinear acoustic fields where Mach numbers are in the range from 0.001 to 0.01 and pressure waveforms have more complicated waveforms than step shocks. The goal of this work was to demonstrate experimentally how nonlinear reflection occurs in air for very weak spherically divergent acoustic spark-generated pulses resembling an N-wave. Measurements of reflection patterns were performed using a Mach-Zehnder interferometer. A thin laser beam with sub-millimeter cross-section was used to obtain the time resolution of 0.4 µs, which is 6 times higher than the time resolution of the condenser microphones. Pressure waveforms were reconstructed using the inverse Abel transform applied to the phase of the signal measured by the interferometer. The Mach stem formation was observed experimentally as a result of collision of the incident and reflected shock pulses. It was shown that irregular reflection of the pulse occurred in a dynamic way and the length of the Mach stem increased linearly while the pulse propagated along the surface. Since the front shock of the spark-generated pulse was steeper than the rear shock, irregular type of reflection was observed only for the front shock of the pulse while the rear shock reflection occurred in a regular regime.

  15. Critical and creative reflective inquiry: surfacing narratives to enable learning and inform action

    NARCIS (Netherlands)

    Rn, MscN Shaun Cardiff

    2012-01-01

    Narratives are being increasingly used in nursing and action research. In this participatory action research study, nurse leaders of an acute care of the older person unit collectively, critically and creatively reflected on lived experiences in order to explore the concept of person-centred

  16. Relationship of intertidal surface sediment chlorophyll concentration to hyper-spectral reflectance and chlorophyll fluorescence

    NARCIS (Netherlands)

    Kromkamp, J.C.; Morris, E.P.; Forster, R.M.; Honeywill, C.; Hagerthey, S.; Paterson, D.M.

    2006-01-01

    Estimating biomass of microphytobenthos (MPB) on intertidal mud flats is extremely difficult due to their patchy occurrence, especially at the scale of an entire mud flat. We tested two optical approaches that can be applied in situ: spectral reflectance and chlorophyll fluorescence. These two

  17. Modeling the Anisotropic Reflectance of a Surface with Microstructure Engineered to Obtain Visible Contrast after Rotation

    DEFF Research Database (Denmark)

    Luongo, Andrea; Falster, Viggo; Doest, Mads Emil Brix

    2017-01-01

    rotating it 90 degrees around its normal axis. We build an analytic anisotropic reflectance model based on the microstructure engineered to obtain such contrast. Using our model to render synthetic images, we predict the above mentioned contrasts and compare our predictions with the measurements reported...

  18. Reflection of P and SV waves at the free surface of a monoclinic ...

    Indian Academy of Sciences (India)

    R.Narasimhan(krishtel emaging)1461 1996 Oct 15 13:05:22

    a monoclinic elastic half-space. Numerical results presented indicate that the anisotropy might affect the reflection coefficients significantly. 2. Basic equations. Consider a homogeneous anisotropic elastic medium of monoclinic type. It has one plane of elastic symmetry and its elastic properties are defined by thirteen elastic ...

  19. Measuring and modeling the effect of surface moisture on the spectral reflectance of coastal beach sand

    NARCIS (Netherlands)

    Nolet, Corjan; Poortinga, Ate; Roosjen, Peter; Bartholomeus, Harm; Ruessink, Gerben|info:eu-repo/dai/nl/169093360

    2014-01-01

    Surface moisture is an important supply limiting factor for aeolian sand transport, which is the primary driver of coastal dune development. As such, it is critical to account for the control of surface moisture on available sand for dune building. Optical remote sensing has the potential to measure

  20. Light reflection by road surfaces : english edition of Communication 53 of the Study Centre for Road Construction (Mededeling 53 'lichtreflectie van wegdekken', 1984.

    NARCIS (Netherlands)

    SCW-Working Group E2; Schreuder, D.A. Schram, J. Burghout, F. Kreeft, S.G. van der Tan, T.H. & Gorkum, F. van

    1984-01-01

    This report deals with the relationship between the light reflecting properties and the composition of road surfaces. For this it is essential to be able to characterise, identify and classify surfaces with regard to their reflection properties. Identification is possible by means of two parameters

  1. Study of Surface Wettability Change of Unconsolidated Sand Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy and Thermogravimetric Analysis.

    Science.gov (United States)

    Gómora-Herrera, Diana; Navarrete Bolaños, Juan; Lijanova, Irina V; Olivares-Xometl, Octavio; Likhanova, Natalya V

    2018-04-01

    The effects exerted by the adsorption of vapors of a non-polar compound (deuterated benzene) and a polar compound (water) on the surface of Ottawa sand and a sample of reservoir sand (Channel), which was previously impregnated with silicon oil or two kinds of surfactants, (2-hydroxyethyl) trimethylammonium oleate (HETAO) and (2-hydroxyethyl)trimethylammonium azelate (HETAA), were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and thermogravimetric analysis (TGA). The surface chemistry of the sandstone rocks was elucidated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). Terminal surface groups such as hydroxyls can strongly adsorb molecules that interact with these surface groups (surfactants), resulting in a wettability change. The wettability change effect suffered by the surface after treating it with surfactants was possible to be detected by the DRIFTS technique, wherein it was observed that the surface became more hydrophobic after being treated with silicon oil and HETAO; the surface became more hydrophilic after treating it with HETAA.

  2. Directional reflectance factors for monitoring spatial changes in soil surface structure and soil organic matter erosion in agricultural systems

    Science.gov (United States)

    Croft, H.; Anderson, K.

    2012-04-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in reduced soil productivity, increased erodibility and a loss of soil organic matter (SOM). The breakdown of soil aggregates through slaking and raindrop impact is linked to organic matter turnover, with subsequently eroded material often displaying proportionally more SOM. A reduction in aggregate stability is reflected in a decline in soil surface roughness (SSR), indicating that a soil structural change can be used to highlight soil vulnerability to SOM loss through mineralisation or erosion. Accurate, spatially-continuous measurements of SSR are therefore needed at a variety of spatial and temporal scales to understand the spatial nature of SOM erosion and deposition. Remotely-sensed data can provide a cost-effective means of monitoring changes in soil surface condition over broad spatial extents. Previous work has demonstrated the ability of directional reflectance factors to monitor soil crusting within a controlled laboratory experiment, due to changes in the levels of self-shadowing effects by soil aggregates. However, further research is needed to test this approach in situ, where other soil variables may affect measured reflectance factors and to investigate the use of directional reflectance factors for monitoring soil erosion processes. This experiment assesses the potential of using directional reflectance factors to monitor changes in SSR, aggregate stability and soil organic carbon (SOC) content for two agricultural conditions. Five soil plots representing tilled and seedbed soils were subjected to different durations of natural rainfall, producing a range of different levels of SSR. Directional reflectance factors were measured concomitantly with sampling for soil structural and biochemical tests at each soil plot. Soil samples were taken to measure aggregate stability (wet sieving), SOC (loss on ignition) and soil moisture (gravimetric method). SSM

  3. Porous Nanomaterials for Ultrabroadband Omnidirectional Anti-Reflection Surfaces with Applications in High Concentration Photovoltaics

    KAUST Repository

    Yao, Yuan

    2016-12-06

    Materials for nanoporous coatings that exploit optimized chemistries and self-assembly processes offer capabilities to reach ≈98% transmission efficiency and negligible scattering losses over the broad wavelength range of the solar spectrum from 350 nm to 1.5 μm, on both flat and curved glass substrates. These nanomaterial anti-reflection coatings also offer wide acceptance angles, up to ±40°, for both s- and p-polarization states of incident light. Carefully controlled bilayer films have allowed for the fabrication of dual-sided, gradient index profiles on plano-convex lens elements. In concentration photovoltaics platforms, the resultant enhancements in the photovoltaics efficiencies are ≈8%, as defined by experimental measurements on systems that use microscale triple-junction solar cells. These materials and their applications in technologies that require control over interface reflections have the potential for broad utility in imaging systems, photolithography, light-emitting diodes, and display technologies.

  4. Virtual Relighting of a Virtualized Scene by Estimating Surface Reflectance Properties

    OpenAIRE

    福富, 弘敦; 町田, 貴史; 横矢, 直和

    2011-01-01

    In mixed reality that merges real and virtual worlds, it is required to interactively manipulate the illumination conditions in a virtualized space. In general, specular reflections in a scene make it difficult to interactively manipulate the illumination conditions. Our goal is to provide an opportunity to simulate the original scene, including diffuse and specular relfections, with novel viewpoints and illumination conditions. Thus, we propose a new method for estimating diffuse and specula...

  5. Reflection of P and SV waves at the free surface of a monoclinic ...

    Indian Academy of Sciences (India)

    R.Narasimhan(krishtel emaging)1461 1996 Oct 15 13:05:22

    of elastic symmetry are obtained in terms of the direction cosines of the propagation vector. It is shown that ... In general, the particle motion is neither ... qP waves at the plane free boundary of a mon- oclinic half-space. In a subsequent paper, Chat- topadhyay et al (1996) studied the reflection of. qSV waves. Since, in both of ...

  6. Role of the substrate reflectance and surface-bulk treatments in CsI quantum efficiency

    CERN Document Server

    Singh, B K; Nitti, M A; Valentini, A

    2003-01-01

    We have experimentally investigated the following aspects related to the quantum efficiency of CsI photocathodes: the type of substrate, the film thickness and the effect of a 'bulk treatment' during the film growth. We discovered that, using a high reflectivity aluminium substrate, the photoemission of very thin CsI film is enhanced. Our study also revealed that photocathodes become less sensitive to moisture when a negative bias voltage is applied to the substrate during the film deposition process.

  7. Gravimetric and density profiling using the combination of surface acoustic waves and neutron reflectivity.

    Science.gov (United States)

    Toolan, Daniel T W; Barker, Robert; Gough, Tim; Topham, Paul D; Howse, Jonathan R; Glidle, Andrew

    2017-02-01

    A new approach is described herein, where neutron reflectivity measurements that probe changes in the density profile of thin films as they absorb material from the gas phase have been combined with a Love wave based gravimetric assay that measures the mass of absorbed material. This combination of techniques not only determines the spatial distribution of absorbed molecules, but also reveals the amount of void space within the thin film (a quantity that can be difficult to assess using neutron reflectivity measurements alone). The uptake of organic solvent vapours into spun cast films of polystyrene has been used as a model system with a view to this method having the potential for extension to the study of other systems. These could include, for example, humidity sensors, hydrogel swelling, biomolecule adsorption or transformations of electroactive and chemically reactive thin films. This is the first ever demonstration of combined neutron reflectivity and Love wave-based gravimetry and the experimental caveats, limitations and scope of the method are explored and discussed in detail. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  8. SPOTS Calibration Example

    Directory of Open Access Journals (Sweden)

    Patterson E.

    2010-06-01

    Full Text Available The results are presented using the procedure outlined by the Standardisation Project for Optical Techniques of Strain measurement to calibrate a digital image correlation system. The process involves comparing the experimental data obtained with the optical measurement system to the theoretical values for a specially designed specimen. The standard states the criteria which must be met in order to achieve successful calibration, in addition to quantifying the measurement uncertainty in the system. The system was evaluated at three different displacement load levels, generating strain ranges from 289 µstrain to 2110 µstrain. At the 289 µstrain range, the calibration uncertainty was found to be 14.1 µstrain, and at the 2110 µstrain range it was found to be 28.9 µstrain. This calibration procedure was performed without painting a speckle pattern on the surface of the metal. Instead, the specimen surface was prepared using different grades of grit paper to produce the desired texture.

  9. Classification of reflected signals from cavitated tooth surfaces using an artificial intelligence technique incorporating a fiber optic displacement sensor

    Science.gov (United States)

    Rahman, Husna Abdul; Harun, Sulaiman Wadi; Arof, Hamzah; Irawati, Ninik; Musirin, Ismail; Ibrahim, Fatimah; Ahmad, Harith

    2014-05-01

    An enhanced dental cavity diameter measurement mechanism using an intensity-modulated fiber optic displacement sensor (FODS) scanning and imaging system, fuzzy logic as well as a single-layer perceptron (SLP) neural network, is presented. The SLP network was employed for the classification of the reflected signals, which were obtained from the surfaces of teeth samples and captured using FODS. Two features were used for the classification of the reflected signals with one of them being the output of a fuzzy logic. The test results showed that the combined fuzzy logic and SLP network methodology contributed to a 100% classification accuracy of the network. The high-classification accuracy significantly demonstrates the suitability of the proposed features and classification using SLP networks for classifying the reflected signals from teeth surfaces, enabling the sensor to accurately measure small diameters of tooth cavity of up to 0.6 mm. The method remains simple enough to allow its easy integration in existing dental restoration support systems.

  10. A universal calibrated model for the evaluation of surface water and groundwater quality: Model development and a case study in China.

    Science.gov (United States)

    Yu, Chunxue; Yin, Xin'an; Li, Zuoyong; Yang, Zhifeng

    2015-11-01

    Water quality evaluation is an important issue in environmental management. Various methods have been used to evaluate the quality of surface water and groundwater. However, all previous studies have used different evaluation models for surface water and groundwater, and the models must be recalibrated due to changes in monitoring indicators in each evaluation. Water quality managers would benefit from a universal and effective model based on a simple expression that would be suitable for all cases of surface water and groundwater, and which could therefore serve as a standard method for a region or country. To meet this requirement, we attempted to develop a universal calibrated model based on the radial basis function neural network. In the new model, the units and values of the evaluation indicators for surface water and groundwater are normalized simultaneously to make the data directly comparable. The model's training inputs comprise the normalized value in each of a water quality indicator's grades (e.g., the nitrate contents defined in a regulatory standard for grades I to V) for all evaluation indicators. The central vector of the Gaussian function is used as the average of the evaluation indicators' normalized standard values for the five grades. The final calibrated model is expressed as an equation rather than in a programming language, and is therefore easier to use. We used the model in a Chinese case study, and found that the model was feasible (it compared well with the results of other models) and simple to use for the evaluation of surface water and groundwater quality. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Study on the surface density of surface-active substances through total-reflection X-ray absorption fine structure measurement.

    Science.gov (United States)

    Kashimoto, Kaoru; Takata, Youichi; Matsuda, Takashi; Ikeda, Norihiro; Matsubara, Hiroki; Takiue, Takanori; Aratono, Makoto; Tanida, Hajime; Watanabe, Iwao

    2006-09-26

    The total-reflection X-ray absorption fine structure (XAFS) method previously employed for the adsorption of dodecyltrimethylammonium bromide (DTAB) at the air/water interface was applied to that in the presence of NaBr. The surface concentration of the bromide ions Gamma(X)(B) of DTAB and NaBr was evaluated by using the Br K-edge absorption jump values of the total-reflection XAFS spectra and was compared to the corresponding value Gamma(H)(B) estimated from the dependence of surface tension on the bulk concentrations of DTAB m(1) and NaBr m(2). The Gamma(X)(B) values trace almost perfectly the Gamma(X)(B) versus m(1) curve up to a concentration near the critical micelle concentration (cmc) and deviate gradually above the concentration. This behavior is basically similar to that of the single DTAB system and ensures that the XAFS method is also applicable to the DTAB system, even in the presence of NaBr. In addition, this method was extended to the single nonionic amphiphile with covalently bonded bromine, and the surface concentrations of 6-bromo-1-hexanol (BrC6OH), Gamma(X)(1) and Gamma(H)(B), were evaluated and compared with each other. It was found that the Gamma(X)(1) value almost perfectly traces the Gamma(H)(1) versus m(1) curve, even at high surface concentrations. The excellent coincidence confirmed that the total-reflection XAFS method can be applied to the nonionic amphiphile system as well as a cationic surfactant with or without an added salt system. Finally, the difference between the Gamma(X)(B) and Gamma(H)(B) values observed in the DTAB with and without an added salt system is briefly described.

  12. Spectral reflectance characteristics of different snow and snow-covered land surface objects and mixed spectrum fitting

    Science.gov (United States)

    Zhang, J.-H.; Zhou, Z.-M.; Wang, P.-J.; Yao, F.-M.; Yang, L.

    2011-01-01

    The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing area. The result showed that for a pure snow spectrum, the snow reflectance peaks appeared from visible to 800 nm band locations; there was an obvious absorption valley of snow spectrum near 1030 nm wavelength. Compared with fresh snow, the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300~1300, 1700~1800 and 2200~2300 nm, the lowest was from the compacted snow and frozen ice. For the vegetation and snow mixed spectral characteristics, it was indicated that the spectral reflectance increased for the snow-covered land types(including pine leaf with snow and pine leaf on snow background), due to the influence of snow background in the range of 350~1300 nm. However, the spectrum reflectance of mixed pixel remained a vegetation spectral characteristic. In the end, based on the spectrum analysis of snow, vegetation, and mixed snow/vegetation pixels, the mixed spectral fitting equations were established, and the results showed that there was good correlation between spectral curves by simulation fitting and observed ones(correlation coefficient R2=0.9509).

  13. Fecal Near-Infrared Reflectance Spectroscopy Prediction of the Feed Value of Temperate Forages for Ruminants and Some Parameters of the Chemical Composition of Feces: Efficiency of Four Calibration Strategies.

    Science.gov (United States)

    Andueza, Donato; Picard, Fabienne; Dozias, Dominique; Aufrère, Jocelyne

    2017-09-01

    The forage feed value determined by organic matter digestibility (OMD) and voluntary intake (VI) is hard and expensive. Thus, several indirect methods such as near infrared reflectance (NIR) spectroscopy have been developed for predicting the feed value of forages. In this study, NIR spectra of 1040 samples of feces from sheep fed fresh temperate forages were used to develop calibration models for the prediction of fecal crude ash (CA), fecal crude protein (CP), fresh forage OMD, and VI. Another 136 samples of feces were used to assess these models. Four calibration strategies were compared: (1) species-specific calibration; (2) family-specific calibration; (3) a global procedure; and (4) a LOCAL approach. The first three strategies were based on classical regression models developed on different sample populations, whereas the LOCAL approach is based on the development models from selected samples spectrally similar to the sample to be predicted. The first two strategies use feces-samples grouping based on the species or the family of the forage ingested. Forage calibration data sets gave value ranges of 79-327 g/kg dry matter (DM) for CA, 65-243 g/kg DM for CP, 0.52-0.85 g/g for OMD, and 34.7-100.5 g DM/kg metabolic body weight (BW 0.75 ) for VI. The prediction of CA and CP content in feces by species-specific fecal NIR (FNIR) spectroscopy models showed lower standard error of prediction (SEP) (CA 15.03 and CP 7.48 g/kg DM) than family-specific (CA 21.93 and CP 7.69 g/kg DM), global (CA 19.83 and CP 7.98 g/kg DM), or LOCAL (CA 30.85 and CP 8.10 g/kg DM) models. For OMD, the LOCAL procedure led to a lower SEP (0.018 g/g) than the other approaches (0.023, 0.024, and 0.023 g/g for species-specific, family-specific, and global models, respectively). For VI, the LOCAL approach again led to a lower SEP (6.15 g/kg BW 0.75 ) than the other approaches (7.35, 8.00, and 8.13 g/kg BW 0.75 for the species-specific, family-specific, and global models

  14. Detection of egg yolk antibodies reflecting Salmonella enteritidis infections using a surface plasmon resonance biosensor

    NARCIS (Netherlands)

    Thomas, M.E.; Bouma, A.; Eerden, van E.; Landman, W.J.M.; Knapen, van F.; Stegeman, J.A.; Bergwerff, A.A.

    2006-01-01

    A surface plasmon resonance (SPR) biosensor assay was developed on the basis of a lipopolysaccharide antigen of Salmonella enterica serovar enteritidis (S. enterica serovar enteritidis) to detect egg yolk antibodies against S. enterica serovar enteritidis. This biosensor assay was compared to two

  15. Processing OMEGA/Mars Express hyperspectral imagery from radiance-at-sensor to surface reflectance

    NARCIS (Netherlands)

    Bakker, W.H.; Ruitenbeek, F.J.A. van; Werff, H.M.A. van der; Zegers, T.E.; Oosthoek, J.H.P.; Marsh, S.H.; Meer, F.D. van der

    2014-01-01

    OMEGA/Mars Express hyperspectral imagery is an excellent source of data for exploring the surface composition of the planet Mars. Compared to terrestrial hyperspectral imagery, the data are challenging to work with; scene-specific transmission models are lacking, spectral features are shallow making

  16. A comparison of reflectance properties on polymer micro-structured functional surface

    DEFF Research Database (Denmark)

    Regi, Francesco; Li, Dongya; Nielsen, Jannik Boll

    by their pitch distance and their angle in respect to the surface (Figure 2). The geometry was obtained by precision milling of a tool steel bar and replicated through silicone replica technology [2], and by hot embossing using Acrylonitrile Butadiene Styrene (ABS). A digital microscope has been used...

  17. Reflection-based fibre-optic refractive index sensor using surface plasmon resonance

    Czech Academy of Sciences Publication Activity Database

    Hlubina, P.; Kadulová, M.; Ciprian, D.; Sobota, Jaroslav

    2014-01-01

    Roč. 9, August 19 (2014), 14033:1-5 ISSN 1990-2573 R&D Projects: GA MŠk(CZ) LO1212 Keywords : surface plasmon resonance * fibre -optic sensor * spectral interrogation technique * aqueous solutions of ethanol * refractive index Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.231, year: 2014

  18. Neutron and X-ray reflection from surface monolayers of a lipopolyoxazoline

    DEFF Research Database (Denmark)

    Wurlitzer, A.; Politsch, E.; Cevc, G.

    2000-01-01

    were investigated as a function of surface pressure. The data are consistent with a fraction of the polyoxazoline moieties in brush-like conformations coexisting with a smaller fraction that is closely associated with the interface. Across the phase transition that is detected in the isotherm...

  19. RESEARCH OF THE ENTRANCE ANGLE EFFECT ON THE REFLECTANCE SPECTRA OF THE STAINLESS STEEL SURFACE OXIDIZED BY PULSED LASER RADIATION

    Directory of Open Access Journals (Sweden)

    V. P. Veiko

    2016-05-01

    Full Text Available Subject of Research.Oxide films on the metal surfaces can be obtained both by surface-uniform infrared heating and local laser treatment e.g. by sequence of nanosecond laser pulses. Due to interference in created films the coloration of treated area is observed. The present work shows the results of spectrophotometric measurements for various light entrance angles in the range of 10-60°. Method. AISI 304 stainless steel plates were oxidized by two methods: in muffle furnace FM - 10 (Т= 500-600° С, t = 5-7 min. and at line-by-line scanning by sequence of nanosecond laser pulses (λ = 1.06 μm, τ =100 ns, r = 25 μm,q=2.91∙107 W/cm2, Nx = 30, Ny = 1. Surface research in optical resolution was realized by Carl Zeiss Axio Imager A1M. Reflectance spectra were obtained with spectrophotometer Lambda Perkin 1050 with integrating sphere at different fixed light incidence angles. Topographic features were detected by scanning probe microscopy investigation with NanoEducator equipment. Main Results. The quantitative surface geometry characteristics of AISI 304 stainless steel patterns treated by different methods are obtained. It was found that the increase of light entrance angle has no influence on the form of reflection coefficient dependence from a wavelength, but a blue-shift occurs especially for the case of laser treatment. This difference can be caused by surface topology formed by laser heating and variety of oxide film thickness. This effect results in more significant change in observed sample color for laser treatment then for infrared heating. Practical Relevance. The results obtained in the present work can be used to implement a new element of product protection against forgery with the product marking.

  20. Coupled retrieval of aerosol properties and land surface reflection using the Airborne Multiangle SpectroPolarimetric Imager

    Science.gov (United States)

    Xu, Feng; van Harten, Gerard; Diner, David J.; Kalashnikova, Olga V.; Seidel, Felix C.; Bruegge, Carol J.; Dubovik, Oleg

    2017-07-01

    The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) has been flying aboard the NASA ER-2 high-altitude aircraft since October 2010. In step-and-stare operation mode, AirMSPI acquires radiance and polarization data in bands centered at 355, 380, 445, 470*, 555, 660*, 865*, and 935 nm (* denotes polarimetric bands). The imaged area covers about 10 km by 11 km and is typically observed from nine viewing angles between ±66° off nadir. For a simultaneous retrieval of aerosol properties and surface reflection using AirMSPI, an efficient and flexible retrieval algorithm has been developed. It imposes multiple types of physical constraints on spectral and spatial variations of aerosol properties as well as spectral and temporal variations of surface reflection. Retrieval uncertainty is formulated by accounting for both instrumental errors and physical constraints. A hybrid Markov-chain/adding-doubling radiative transfer (RT) model is developed to combine the computational strengths of these two methods in modeling polarized RT in vertically inhomogeneous and homogeneous media, respectively. Our retrieval approach is tested using 27 AirMSPI data sets with low to moderately high aerosol loadings, acquired during four NASA field campaigns plus one AirMSPI preengineering test flight. The retrieval results including aerosol optical depth, single-scattering albedo, aerosol size and refractive index are compared with Aerosol Robotic Network reference data. We identify the best angular combinations for 2, 3, 5, and 7 angle observations from the retrieval quality assessment of various angular combinations. We also explore the benefits of polarimetric and multiangular measurements and target revisits in constraining aerosol property and surface reflection retrieval.

  1. In Situ Nondestructive Analysis of Kalanchoe pinnata Leaf Surface Structure by Polarization-Modulation Infrared Reflection-Absorption Spectroscopy.

    Science.gov (United States)

    Hama, Tetsuya; Kouchi, Akira; Watanabe, Naoki; Enami, Shinichi; Shimoaka, Takafumi; Hasegawa, Takeshi

    2017-12-14

    The outermost surface of the leaves of land plants is covered with a lipid membrane called the cuticle that protects against various stress factors. Probing the molecular-level structure of the intact cuticle is highly desirable for understanding its multifunctional properties. We report the in situ characterization of the surface structure of Kalanchoe pinnata leaves using polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS). Without sample pretreatment, PM-IRRAS measures the IR spectra of the leaf cuticle of a potted K. pinnata plant. The peak position of the CH 2 -related modes shows that the cuticular waxes on the leaf surface are mainly crystalline, and the alkyl chains are highly packed in an all-trans zigzag conformation. The surface selection rule of PM-IRRAS revealed the average orientation of the cuticular molecules, as indicated by the positive and negative signals of the IR peaks. This unique property of PM-IRRAS revealed that the alkyl chains of the waxes and the main chains of polysaccharides are oriented almost perpendicular to the leaf surface. The nondestructive, background-free, and environmental gas-free nature of PM-IRRAS allows the structure and chemistry of the leaf cuticle to be studied directly in its native environment.

  2. Frequency averaging of fluctuations in the cross-correlation reception of noiselike signals reflected from a rough sea surface

    Science.gov (United States)

    Baranov, V. F.; Gerasimova, T. I.; Gulin, É. P.

    2007-04-01

    For noiselike signals reflected from a rough sea surface and received by a correlation receiver, the effect achieved at the receiver output as a result of frequency averaging of signal fluctuations is considered. Expressions characterizing the effect of frequency averaging are derived by using the generalized two-scale model describing the frequency correlation of strong fluctuations of the transfer function. Results of numerical calculations for the variance of fluctuations at the output of the correlation receiver are presented for different relative values of the frequency bandwidth of noiselike signals and the frequency correlation scales for the cases of both weak and strong fluctuations.

  3. Spatial and energy distributions of satellite-speed helium atoms reflected from satellite-type surfaces

    International Nuclear Information System (INIS)

    Liu, S.M.; Rodgers, W.E.; Knuth, E.L.

    1977-01-01

    Interactions of satellite-speed helium atoms (accelerated in an expansion from an arc-heated supersonic-molecular-beam source) with practical satellite surfaces have been investigated experimentally. The density and energy distributions of the scattered atoms were measured using a detection system developed for this study. This detection system includes (a) a target positioning mechanism, (b) a detector rotating mechanism, and (c) a mass spectrometer and/or a retarding-field energy analyzer. (Auth.)

  4. On fatigue crack growth mechanisms of MMC: Reflection on analysis of 'multi surface initiations'

    International Nuclear Information System (INIS)

    Mkaddem, A.; El Mansori, M.

    2009-01-01

    This work attempts to examine the mechanisms of fatigue when cracks synergetically initiate in more than one site at the specimen surface. The metal matrix composites (MMC) i.e. silicon carbide particles reinforced aluminium matrix composites (Al/SiC p -MMC), seem to be good candidates to accelerate fatigue failures following multi surface initiations (MSI). Closure effects of MSI mechanisms on the variation of fatigue behaviour are explored for various stress states. Experiments were carried out using non pre-treated and pre-treated specimens. Using an Equivalent Ellipse Method (EEM), it is shown that the aspect of surface finish of specimen plays an important role on crack growth. Scanning Electron Microscope (SEM) inspections have lead to distinguishing the initiation regions from propagation regions and final separation regions. It is also revealed that the total lifetime of specimens is sensitive to heat treatment. Moreover, it is found that the appearance of MSI in cycled materials is more probable at high level of fatigue loads.

  5. Deriving surface soil moisture from reflected GNSS signal observations from a grassland site in southwestern France

    Directory of Open Access Journals (Sweden)

    S. Zhang

    2018-03-01

    Full Text Available This work assesses the estimation of surface volumetric soil moisture (VSM using the global navigation satellite system interferometric reflectometry (GNSS-IR technique. Year-round observations were acquired from a grassland site in southwestern France using an antenna consecutively placed at two contrasting heights above the ground surface (3.3 and 29.4 m. The VSM retrievals are compared with two independent reference datasets: in situ observations of soil moisture, and numerical simulations of soil moisture and vegetation biomass from the ISBA (Interactions between Soil, Biosphere and Atmosphere land surface model. Scaled VSM estimates can be retrieved throughout the year removing vegetation effects by the separation of growth and senescence periods and by the filtering of the GNSS-IR observations that are most affected by vegetation. Antenna height has no significant impact on the quality of VSM estimates. Comparisons between the VSM GNSS-IR retrievals and the in situ VSM observations at a depth of 5 cm show good agreement (R2 =  0.86 and RMSE  =  0.04 m3 m−3. It is shown that the signal is sensitive to the grass litter water content and that this effect triggers differences between VSM retrievals and in situ VSM observations at depths of 1 and 5 cm, especially during light rainfall events.

  6. Proteome of conidial surface associated proteins of Aspergillus fumigatus reflecting potential vaccine candidates and allergens.

    Science.gov (United States)

    Asif, Abdul R; Oellerich, Michael; Amstrong, Victor W; Riemenschneider, Birgit; Monod, Michel; Reichard, Utz

    2006-04-01

    Aspergillus fumigatus is a mold causing most of the invasive fungal lung infections in the immunocompromised host. In addition, the species is the causative agent of certain allergic diseases. Both in invasive and in allergic diseases, the conidial surface mediates the first contact with the human immune system. Thus, conidial surface proteins may be reasonable vaccine candidates as well as important allergens. To broaden the list of those antigens, intact viable Aspergillus conidia were extracted with mild alkaline buffer at pH 8.5 in the presence of a 1,3-beta-glucanase. The proteome of this fraction was separated by two- dimensional gel electrophoresis (2-DE) and analyzed by liquid chromatography coupled with tandem mass spectrometry. Altogether 26 different A. fumigatus proteins were identified, twelve of which contain a signal for secretion. Among these were the known major conidial surface protein rodlet A, one acid protease PEP2, one lipase, a putative disulfide isomerase and a putative fructose-1,6-biphosphatase. The known allergen Aspf 3 was identified among the proteins without a signal for secretion. On the basis of the recently annotated A. fumigatus genome (Nature 2005, 438, 1151-1156), proteome analysis is now a powerful tool to confirm expression of hypothetical proteins and, thereby to identify additional vaccine candidates and possible new allergens of this important fungal pathogen.

  7. Deriving surface soil moisture from reflected GNSS signal observations from a grassland site in southwestern France

    Science.gov (United States)

    Zhang, Sibo; Calvet, Jean-Christophe; Darrozes, José; Roussel, Nicolas; Frappart, Frédéric; Bouhours, Gilles

    2018-03-01

    This work assesses the estimation of surface volumetric soil moisture (VSM) using the global navigation satellite system interferometric reflectometry (GNSS-IR) technique. Year-round observations were acquired from a grassland site in southwestern France using an antenna consecutively placed at two contrasting heights above the ground surface (3.3 and 29.4 m). The VSM retrievals are compared with two independent reference datasets: in situ observations of soil moisture, and numerical simulations of soil moisture and vegetation biomass from the ISBA (Interactions between Soil, Biosphere and Atmosphere) land surface model. Scaled VSM estimates can be retrieved throughout the year removing vegetation effects by the separation of growth and senescence periods and by the filtering of the GNSS-IR observations that are most affected by vegetation. Antenna height has no significant impact on the quality of VSM estimates. Comparisons between the VSM GNSS-IR retrievals and the in situ VSM observations at a depth of 5 cm show good agreement (R2 = 0.86 and RMSE = 0.04 m3 m-3). It is shown that the signal is sensitive to the grass litter water content and that this effect triggers differences between VSM retrievals and in situ VSM observations at depths of 1 and 5 cm, especially during light rainfall events.

  8. High-directional light source using photon recycling with a retro-reflective Dome incorporated with a textured LED die surface.

    Science.gov (United States)

    Sun, Ching-Cherng; Chung, Shuang-Chao; Yang, Shuang-Hao; Yu, Yeh-Wei; Chien, Wei-Ting; Chen, Huang-Kuen; Chen, Shih-Peng

    2013-07-29

    This paper demonstrates a novel retro-reflective dome that enhances the directionality of a light emitting diode (LED) by recycling photons reflected by a textured LED die surface. A simulation model is developed to describe both the photon recycling process within the dome and the role of specific pyramid patterns on the top surface of the LED die. Advanced simulations showed that a perfectly polished surface with 100% reflectivity potentially enhances the directionality of the dome by 340%, 250%, and 240% using reflective domes with 10°, 20°, and 30° light cones, respectively. In the experiment, the directionality of the domes exhibiting surface imperfections is enhanced by approximately 160%, 150%, and 130% using 10°, 20°, and 30° light cones, respectively. By incorporating a textured top surface on the LED die, the proposed dome effectively increases the directionality of the LED light source.

  9. Development of Surfaces Optically Suitable for Flat Solar Panels. [using a reflectometer which separately evaluates spectral and diffuse reflectivities of surfaces

    Science.gov (United States)

    1979-01-01

    A reflectometer which can separately evaluate the spectral and diffuse reflectivities of surfaces is described. A phase locked detection system for the reflectometer is also described. A selective coating on aluminum potentially useful for flat plate solar collector applications is presented. The coating is composed of strongly bound copper oxide (divalent) and is formed by an etching process performed on an aluminum alloy with high copper content. Fabrication costs are expected to be small due to the one stop fabrication process. A number of conclusions gathered from the literature as to the required optical properties of flat plate solar collectors are discussed.

  10. Optical properties of nucleobase thin films as studied by attenuated total reflection and surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Kim, MinSuk; Ham, Won Kyu; Kim, Wonyoung; Hwangbo, Chang Kwon; Choi, Eun Ha; Lee, Geon Joon

    2018-04-01

    Optical properties of nucleobase thin films were studied by attenuated total reflection (ATR) and surface-enhanced Raman spectroscopy (SERS). Adenine and guanine films were deposited on fused silica and silver at room temperature by thermal evaporation, and the normal dispersion of refractive indices of transparent adenine and guanine films in the visible and near-infrared regions were analyzed. The measured ATR spectra of adenine (guanine) films and numerical simulations by optical transfer matrix formalism demonstrate that the shift of surface plasmon resonance (SPR) wavelength is approximately linearly proportional to the adenine (guanine) film thickness, indicating that SPR can be used for quantitative measurements of biomaterials. The Raman spectra indicated that the adenine (guanine) films can be deposited by thermal evaporation. The adenine (guanine) films on silver exhibited Raman intensity enhancement as compared to those on glass, which was attributed to the SPR effect of silver platform and might play a role as a hot plate for SERS detection of biomaterials.

  11. Calibration of passive remote observing optical and microwave instrumentation; Proceedings of the Meeting, Orlando, FL, Apr. 3-5, 1991

    Science.gov (United States)

    Guenther, Bruce W.

    Various papers on the calibration of passive remote observing optical and microwave instrumentation are presented. Individual topics addressed include: on-board calibration device for a wide field-of-view instrument, calibration for the medium-resolution imaging spectrometer, cryogenic radiometers and intensity-stabilized lasers for EOS radiometric calibrations, radiometric stability of the Shuttle-borne solar backscatter ultraviolet spectrometer, ratioing radiometer for use with a solar diffuser, requirements of a solar diffuser and measurements of some candidate materials, reflectance stability analysis of Spectralon diffuse calibration panels, stray light effects on calibrations using a solar diffuser, radiometric calibration of SPOT 23 HRVs, surface and aerosol models for use in radiative transfer codes. Also addressed are: calibrated intercepts for solar radiometers used in remote sensor calibration, radiometric calibration of an airborne multispectral scanner, in-flight calibration of a helicopter-mounted Daedalus multispectral scanner, technique for improving the calibration of large-area sphere sources, remote colorimetry and its applications, spatial sampling errors for a satellite-borne scanning radiometer, calibration of EOS multispectral imaging sensors and solar irradiance variability. (For individual items see A93-23576 to A93-23603)

  12. Modeling of Microwave Reflection from the Surface of Water Basins with Spills of Water-Cut Oil

    Science.gov (United States)

    Krotikov, V. D.; Pelushenko, S. A.; Rakut', I. V.; Savelyev, V. Yu.

    2015-06-01

    We consider specific features of reflection of microwaves from the surface of a water basin for the two-layer model of oil spills, which are determined by a water-cut-oil film. Within the spill model, the dielectric properties of water were allowed for in accordance with the Debye theory, and the dielectric properties of the water-cut oil, in accordance with the theory developed for binary systems. The data about variations in the values of reflection coefficients depending on the frequency, viewing angle, thickness of the oil film, and moisture content in the film are obtained. The dependences of reflection coefficients on the film thickness are determined for various values of volume content of the water fraction in oil. Complex values of the dielectric permittivity of oil-water emulsions with preset volume moisture content are found. Describing the obtained dependences of the complex dielectric permittivity of the emulsion on the volume moisture content requires application of asymmetrical formulas for the mixture of polar and nonpolar fluids.

  13. 1D Seismic reflection technique to increase depth information in surface seismic investigations

    Science.gov (United States)

    Camilletti, Stefano; Fiera, Francesco; Umberto Pacini, Lando; Perini, Massimiliano; Prosperi, Andrea

    2017-04-01

    1D seismic methods, such as MASW Re.Mi. and HVSR, have been extensively used in engineering investigations, bedrock research, Vs profile and to some extent for hydrologic applications, during the past 20 years. Recent advances in equipment, sound sources and computer interpretation techniques, make 1D seismic methods highly effective in shallow subsoil modeling. Classical 1D seismic surveys allows economical collection of subsurface data however they fail to return accurate information for depths greater than 50 meters. Using a particular acquisition technique it is possible to collect data that can be quickly processed through reflection technique in order to obtain more accurate velocity information in depth. Furthermore, data processing returns a narrow stratigraphic section, alongside the 1D velocity model, where lithological boundaries are represented. This work will show how collect a single-CMP to determine: (1) depth of bedrock; (2) gravel layers in clayey domains; (3) accurate Vs profile. Seismic traces was processed by means a new software developed in collaboration with SARA electronics instruments S.r.l company, Perugia - ITALY. This software has the great advantage of being able to be used directly in the field in order to reduce the times elapsing between acquisition and processing.

  14. Detection of aflatoxin and surface mould contaminated figs by using Fourier transform near-infrared reflectance spectroscopy.

    Science.gov (United States)

    Durmuş, Efkan; Güneş, Ali; Kalkan, Habil

    2017-01-01

    Aflatoxins are toxic metabolites that are mainly produced by members of the Aspergillus section Flavi on many agricultural products. Certain agricultural products such as figs are known to be high risk products for aflatoxin contamination. Aflatoxin contaminated figs may show a bright greenish yellow fluorescence (BGYF) under ultraviolet (UV) light at a wavelength of 365 nm. Traditionally, BGYF positive figs are manually selected by workers. However, manual selection depends on the expertise level of the workers and it may cause them skin-related health problems due to UV radiation. In this study, we propose a non-invasive approach to detect aflatoxin and surface mould contaminated figs by using Fourier transform near-infrared (FT-NIR) reflectance spectroscopy. A classification accuracy of 100% is achieved for classifying the figs into aflatoxin contaminated/uncontaminated and surface mould contaminated/uncontaminated categories. In addition, a strong correlation has been found between aflatoxin and surface mould. Combined with pattern classification methods, the NIR spectroscopy can be used to detect aflatoxin contaminated figs non-invasively. Furthermore, a positive correlation between surface mould and aflatoxin contamination leads to a promising alternative indicator for the detection of aflatoxin-contaminated figs. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  15. Surface reflectance and conversion efficiency dependence of technologies for mitigating global warming

    Energy Technology Data Exchange (ETDEWEB)

    Edmonds, Ian [Solartran Pty Ltd., 12 Lentara St, Kenmore, Brisbane 4069 (Australia); Smith, Geoff [Physics and Advanced Materials, University of Technology, Sydney, PO Box 123, Broadway, New South Wales 2007 (Australia)

    2011-05-15

    A means of assessing the relative impact of different renewable energy technologies on global warming has been developed. All power plants emit thermal energy to the atmosphere. Fossil fuel power plants also emit CO{sub 2} which accumulates in the atmosphere and provides an indirect increase in global warming via the greenhouse effect. A fossil fuel power plant may operate for some time before the global warming due to its CO{sub 2} emission exceeds the warming due to its direct heat emission. When a renewable energy power plant is deployed instead of a fossil fuel power plant there may be a significant time delay before the direct global warming effect is less than the combined direct and indirect global warming effect from an equivalent output coal fired plant - the ''business as usual'' case. Simple expressions are derived to calculate global temperature change as a function of ground reflectance and conversion efficiency for various types of fossil fuelled and renewable energy power plants. These expressions are used to assess the global warming mitigation potential of some proposed Australian renewable energy projects. The application of the expressions is extended to evaluate the deployment in Australia of current and new geo-engineering and carbon sequestration solutions to mitigate global warming. Principal findings are that warming mitigation depends strongly on the solar to electric conversion efficiency of renewable technologies, geo-engineering projects may offer more economic mitigation than renewable energy projects and the mitigation potential of reforestation projects depends strongly on the location of the projects. (author)

  16. Importance of material matching in the calibration of asymmetric flow field-flow fractionation: material specificity and nanoparticle surface coating effects on retention time

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Haiou [U.S. Food and Drug Administration, Office of Regulatory Affairs, Arkansas Regional Laboratory (United States); Quevedo, Ivan R. [Universidad Iberoamericana, Departamento de Ingeniería y Ciencias Químicas (Mexico); Linder, Sean W.; Fong, Andrew; Mudalige, Thilak K., E-mail: Thilak.Mudalige@fda.hhs.gov [U.S. Food and Drug Administration, Office of Regulatory Affairs, Arkansas Regional Laboratory (United States)

    2016-10-15

    Asymmetric flow field-flow fractionation (AF4) coupled with dynamic light scattering or multiangle light scattering detectors is a promising technique for the size-based separation of colloidal particles (nano- and submicron scale) and the online determination of the particle size of the separated fractions in aqueous suspensions. In most cases, the applications of these detectors are problematic due to the material-specific properties of the analyte that results in erroneous calculations, and as an alternative, different nanoparticle size standards are required to properly calibrate the size-based retention in AF4. The availability of nanoparticle size standards in different materials is limited, and this deviation from ideal conditions of retention is mainly due to material-specific and particle coating-specific membrane–particle interactions. Here, we present an experimental method on the applicability of polystyrene nanoparticles (PS NP) as standard for AF4 calibration and compare with gold nanoparticle (Au NP) standards having different nominal sizes and surface functionalities.

  17. Site Calibration

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    This Site Calibration report is describing the results of a measured site calibration for a site in Denmark. The calibration is carried out by DTU Wind Energy in accordance with Ref.[3] and Ref.[4]. The measurement period is given. The site calibration is carried out before a power performance...... measurement on a given turbine to clarify the influence from the terrain on the ratio between the wind speed at the center of the turbine hub and at the met mast. The wind speed at the turbine is measured by a temporary mast placed at the foundation for the turbine. The site and measurement equipment...... is detailed described in [1] and [2]. All parts of the sensors and the measurement system have been installed by DTU Wind Energy....

  18. Analysis of Visible/SWIR surface reflectance ratios for aerosol retrievals from satellite in Mexico City urban area

    Directory of Open Access Journals (Sweden)

    A. D. de Almeida Castanho

    2007-10-01

    Full Text Available The surface reflectance ratio between the visible (VIS and shortwave infrared (SWIR radiation is an important quantity for the retrieval of the aerosol optical depth (τa from the MODIS sensor data. Based on empirically determined VIS/SWIR ratios, MODIS τa retrieval uses the surface reflectance in the SWIR band (2.1 µm, where the interaction between solar radiation and the aerosol layer is small, to predict the visible reflectances in the blue (0.47 µm and red (0.66 µm bands. Therefore, accurate knowledge of the VIS/SWIR ratio is essential for achieving accurate retrieval of aerosol optical depth from MODIS. We analyzed the surface reflectance over some distinct surface covers in and around the Mexico City metropolitan area (MCMA using MODIS radiances at 0.66 µm and 2.1 µm. The analysis was performed at 1.5 km×1.5 km spatial resolution. Also, ground-based AERONET sun-photometer data acquired in Mexico City from 2002 to 2005 were analyzed for aerosol depth and other aerosol optical properties. In addition, a network of hand-held sun-photometers deployed in Mexico City, as part of the MCMA-2006 Study during the MILAGRO Campaign, provided an unprecedented measurement of τa in 5 different sites well distributed in the city. We found that the average RED/SWIR ratio representative of the urbanized sites analyzed is 0.73±0.06 for scattering angles <140° and goes up to 0.77±0.06 for higher ones. The average ratio for non-urban sites was significantly lower (approximately 0.55. In fact, this ratio strongly depends on differences in urbanization levels (i.e. relative urban to vegetation proportions and types of surface materials. The aerosol optical depth retrieved from MODIS radiances at a spatial resolution of 1.5 km×1.5 km and averaged within 10×10 km boxes were compared with collocated 1-h τa averaged from sun-photometer measurements. The use of the new RED

  19. The calibration of specular gloss meters and gloss plates

    Science.gov (United States)

    Li, Tiecheng; Lai, Lei; Yin, Dejin; Ji, Muyao; Lin, Fangsheng; Shi, Leibing; Xia, Ming; Fu, Yi

    2017-10-01

    Specular gloss is the perception by an observer of the mirror-like appearance of a surface. Specular gloss is usually measured by a glossmeter, which can be calibrated by a group of gloss plates according to JJG 696-2015. The characteristics of a gloss meter include stability, zero error, and error of indication. The characteristics of a gloss plate include roughness and spectral transmissivity of a high gloss plate, spectral reflectivity of a ceramic gloss plate. The experiment results indicate that calibration of both gloss meters and gloss plates should be carefully performed according to the latest verification regulation in order to reduce the measurement error.

  20. Calibration aspects of the JEM-EUSO mission

    Science.gov (United States)

    Adams, J. H.; Ahmad, S.; Albert, J.-N.; Allard, D.; Anchordoqui, L.; Andreev, V.; Anzalone, A.; Arai, Y.; Asano, K.; Ave Pernas, M.; Baragatti, P.; Barrillon, P.; Batsch, T.; Bayer, J.; Bechini, R.; Belenguer, T.; Bellotti, R.; Belov, K.; Berlind, A. A.; Bertaina, M.; Biermann, P. L.; Biktemerova, S.; Blaksley, C.; Blanc, N.; Błȩcki, J.; Blin-Bondil, S.; Blümer, J.; Bobik, P.; Bogomilov, M.; Bonamente, M.; Briggs, M. S.; Briz, S.; Bruno, A.; Cafagna, F.; Campana, D.; Capdevielle, J.-N.; Caruso, R.; Casolino, M.; Cassardo, C.; Castellinic, G.; Catalano, C.; Catalano, G.; Cellino, A.; Chikawa, M.; Christl, M. J.; Cline, D.; Connaughton, V.; Conti, L.; Cordero, G.; Crawford, H. J.; Cremonini, R.; Csorna, S.; Dagoret-Campagne, S.; de Castro, A. J.; De Donato, C.; de la Taille, C.; De Santis, C.; del Peral, L.; Dell'Oro, A.; De Simone, N.; Di Martino, M.; Distratis, G.; Dulucq, F.; Dupieux, M.; Ebersoldt, A.; Ebisuzaki, T.; Engel, R.; Falk, S.; Fang, K.; Fenu, F.; Fernández-Gómez, I.; Ferrarese, S.; Finco, D.; Flamini, M.; Fornaro, C.; Franceschi, A.; Fujimoto, J.; Fukushima, M.; Galeotti, P.; Garipov, G.; Geary, J.; Gelmini, G.; Giraudo, G.; Gonchar, M.; González Alvarado, C.; Gorodetzky, P.; Guarino, F.; Guzmán, A.; Hachisu, Y.; Harlov, B.; Haungs, A.; Hernández Carretero, J.; Higashide, K.; Ikeda, D.; Ikeda, H.; Inoue, N.; Inoue, S.; Insolia, A.; Isgrò, F.; Itow, Y.; Joven, E.; Judd, E. G.; Jung, A.; Kajino, F.; Kajino, T.; Kaneko, I.; Karadzhov, Y.; Karczmarczyk, J.; Karus, M.; Katahira, K.; Kawai, K.; Kawasaki, Y.; Keilhauer, B.; Khrenov, B. A.; Kim, J.-S.; Kim, S.-W.; Kim, S.-W.; Kleifges, M.; Klimov, P. A.; Kolev, D.; Kreykenbohm, I.; Kudela, K.; Kurihara, Y.; Kusenko, A.; Kuznetsov, E.; Lacombe, M.; Lachaud, C.; Lee, J.; Licandro, J.; Lim, H.; López, F.; Maccarone, M. C.; Mannheim, K.; Maravilla, D.; Marcelli, L.; Marini, A.; Martinez, O.; Masciantonio, G.; Mase, K.; Matev, R.; Medina-Tanco, G.; Mernik, T.; Miyamoto, H.; Miyazaki, Y.; Mizumoto, Y.; Modestino, G.; Monaco, A.; Monnier-Ragaigne, D.; Morales de los Ríos, J. A.; Moretto, C.; Morozenko, V. S.; Mot, B.; Murakami, T.; Murakami, M. Nagano; Nagata, M.; Nagataki, S.; Nakamura, T.; Napolitano, T.; Naumov, D.; Nava, R.; Neronov, A.; Nomoto, K.; Nonaka, T.; Ogawa, T.; Ogio, S.; Ohmori, H.; Olinto, A. V.; Orleański, P.; Osteria, G.; Panasyuk, M. I.; Parizot, E.; Park, I. H.; Park, H. W.; Pastircak, B.; Patzak, T.; Paul, T.; Pennypacker, C.; Perez Cano, S.; Peter, T.; Picozza, P.; Pierog, T.; Piotrowski, L. W.; Piraino, S.; Plebaniak, Z.; Pollini, A.; Prat, P.; Prévôt, G.; Prieto, H.; Putis, M.; Reardon, P.; Reyes, M.; Ricci, M.; Rodríguez, I.; Rodríguez Frías, M. D.; Ronga, F.; Roth, M.; Rothkaehl, H.; Roudil, G.; Rusinov, I.; Rybczyński, M.; Sabau, M. D.; Sáez-Cano, G.; Sagawa, H.; Saito, A.; Sakaki, N.; Sakata, M.; Salazar, H.; Sánchez, S.; Santangelo, A.; Santiago Crúz, L.; Sanz Palomino, M.; Saprykin, O.; Sarazin, F.; Sato, H.; Sato, M.; Schanz, T.; Schieler, H.; Scotti, V.; Segreto, A.; Selmane, S.; Semikoz, D.; Serra, M.; Sharakin, S.; Shibata, T.; Shimizu, H. M.; Shinozaki, K.; Shirahama, T.; Siemieniec-Oziȩbło, G.; Silva López, H. H.; Sledd, J.; Słomińska, K.; Sobey, A.; Sugiyama, T.; Supanitsky, D.; Suzuki, M.; Szabelska, B.; Szabelski, J.; Tajima, F.; Tajima, N.; Tajima, T.; Takahashi, Y.; Takami, H.; Takeda, M.; Takizawa, Y.; Tenzer, C.; Tibolla, O.; Tkachev, L.; Tokuno, H.; Tomida, T.; Tone, N.; Toscano, S.; Trillaud, F.; Tsenov, R.; Tsunesada, Y.; Tsuno, K.; Tymieniecka, T.; Uchihori, Y.; Unger, M.; Vaduvescu, O.; Valdés-Galicia, J. F.; Vallania, P.; Valore, L.; Vankova, G.; Vigorito, C.; Villaseñor, L.; von Ballmoos, P.; Wada, S.; Watanabe, J.; Watanabe, S.; Watts, J.; Weber, M.; Weiler, T. J.; Wibig, T.; Wiencke, L.; Wille, M.; Wilms, J.; Włodarczyk, Z.; Yamamoto, T.; Yamamoto, Y.; Yang, J.; Yano, H.; Yashin, I. V.; Yonetoku, D.; Yoshida, K.; Yoshida, S.; Young, R.; Zotov, M. Yu.; Zuccaro Marchi, A.

    2015-11-01

    The JEM-EUSO telescope will be, after calibration, a very accurate instrument which yields the number of received photons from the number of measured photo-electrons. The project is in phase A (demonstration of the concept) including already operating prototype instruments, i.e. many parts of the instrument have been constructed and tested. Calibration is a crucial part of the instrument and its use. The focal surface (FS) of the JEM-EUSO telescope will consist of about 5000 photo-multiplier tubes (PMTs), which have to be well calibrated to reach the required accuracy in reconstructing the air-shower parameters. The optics system consists of 3 plastic Fresnel (double-sided) lenses of 2.5 m diameter. The aim of the calibration system is to measure the efficiencies (transmittances) of the optics and absolute efficiencies of the entire focal surface detector. The system consists of 3 main components: (i) Pre-flight calibration devices on ground, where the efficiency and gain of the PMTs will be measured absolutely and also the transmittance of the optics will be. (ii) On-board relative calibration system applying two methods: a) operating during the day when the JEM-EUSO lid will be closed with small light sources on board. b) operating during the night, together with data taking: the monitoring of the background rate over identical sites. (iii) Absolute in-flight calibration, again, applying two methods: a) measurement of the moon light, reflected on high altitude, high albedo clouds. b) measurements of calibrated flashes and tracks produced by the Global Light System (GLS). Some details of each calibration method will be described in this paper.

  1. SSMS near surface analysis of B in irradiated Zircaloy-2: ion implantation standards as a calibration technique

    International Nuclear Information System (INIS)

    Christie, W.H.; Carter, J.A.; Eby, R.E.; Landau, L.; Musick, W.R.

    1980-01-01

    Purpose of this study was to determine the amount of 10 B contamination on the surface of Zircaloy-2 clad irradiated fuel elements that had been stored in an aqueous solution containing 5000 wt. ppM enriched B. SMSS indicated that the contamination was less than 0.06 μg/cm 2

  2. Qualitative and simultaneous quantitative analysis of cimetidine polymorphs by ultraviolet-visible and shortwave near-infrared diffuse reflectance spectroscopy and multivariate calibration models.

    Science.gov (United States)

    Feng, Yuyan; Li, Xiangling; Xu, Kailin; Zou, Huayu; Li, Hui; Liang, Bing

    2015-02-01

    The object of the present study was to investigate the feasibility of applying ultraviolet-visible and shortwave near-infrared diffuse reflectance spectroscopy (UV-vis-SWNIR DRS) coupled with chemometrics in qualitative and simultaneous quantitative analysis of drug polymorphs, using cimetidine as a model drug. Three polymorphic forms (A, B and D) and a mixed crystal (M1) of cimetidine, obtained by preparation under different crystallization conditions, were characterized by microscopy, X-ray powder diffraction (XRPD) and infrared spectroscopy (IR). The discriminant models of four forms (A, B, D and M1) were established by discriminant partial least squares (PLS-DA) using different pretreated spectra. The R and RMSEP of samples in the prediction set by discriminant model with original spectra were 0.9959 and 0.1004. Among the quantitative models of binary mixtures (A and D) established by partial least squares (PLS) and least squares-support vector machine (LS-SVM) with different pretreated spectra, the LS-SVM models based on original and MSC spectra had better prediction effect with a R of 1.0000 and a RMSEP of 0.0134 for form A, and a R of 1.0000 and a RMSEP of 0.0024 for form D. For ternary mixtures, the established PLS quantitative models based on normalized spectra had relatively better prediction effect for forms A, B and D with R of 0.9901, 0.9820 and 0.9794 and RMSEP of 0.0471, 0.0529 and 0.0594, respectively. This research indicated that UV-vis-SWNIR DRS can be used as a simple, rapid, nondestructive qualitative and quantitative method for the analysis of drug polymorphs. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Cross-calibration of the Terra MODIS, Landsat 7 ETM+ and EO-1 ALI sensors using near-simultaneous surface observation over the Railroad Valley Playa, Nevada, test site

    Science.gov (United States)

    Chander, G.; Angal, A.; Choi, T.; Meyer, D.J.; Xiong, X.; Teillet, P.M.

    2007-01-01

    A cross-calibration methodology has been developed using coincident image pairs from the Terra Moderate Resolution Imaging Spectroradiometer (MODIS), the Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) and the Earth Observing EO-1 Advanced Land Imager (ALI) to verify the absolute radiometric calibration accuracy of these sensors with respect to each other. To quantify the effects due to different spectral responses, the Relative Spectral Responses (RSR) of these sensors were studied and compared by developing a set of "figures-of-merit." Seven cloud-free scenes collected over the Railroad Valley Playa, Nevada (RVPN), test site were used to conduct the cross-calibration study. This cross-calibration approach was based on image statistics from near-simultaneous observations made by different satellite sensors. Homogeneous regions of interest (ROI) were selected in the image pairs, and the mean target statistics were converted to absolute units of at-sensor reflectance. Using these reflectances, a set of cross-calibration equations were developed giving a relative gain and bias between the sensor pair.

  4. Impact of dielectric parameters on the reflectivity of 3C–SiC wafers with a rough surface morphology in the reststrahlen region

    Energy Technology Data Exchange (ETDEWEB)

    Engelbrecht, J.A.A., E-mail: Japie.Engelbrecht@nmmu.ac.za [Physics Department, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Janzén, E.; Henry, A. [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Rooyen, I.J. van [Fuel Performance and Design Department, Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415-6188 (United States)

    2014-04-15

    A layer-on-substrate model is used to obtain the infrared reflectance for 3C–SiC with a rough surface morphology. The effect of varying dielectric parameters of the “damaged layer” on the observed reflectivity of the 3C–SiC in the reststrahlen region is assessed. Different simulated reflectance spectra are obtained to those if the dielectric parameters of the “substrate” were varied. Most notable changes in the shape of the simulated reststrahlen peak are observed for changes in the high frequency dielectric constant, the phonon damping constant, the phonon frequencies and “thickness” of damaged surface layer.

  5. Impact of dielectric parameters on the reflectivity of 3C–SiC wafers with a rough surface morphology in the reststrahlen region

    International Nuclear Information System (INIS)

    Engelbrecht, J.A.A.; Janzén, E.; Henry, A.; Rooyen, I.J. van

    2014-01-01

    A layer-on-substrate model is used to obtain the infrared reflectance for 3C–SiC with a rough surface morphology. The effect of varying dielectric parameters of the “damaged layer” on the observed reflectivity of the 3C–SiC in the reststrahlen region is assessed. Different simulated reflectance spectra are obtained to those if the dielectric parameters of the “substrate” were varied. Most notable changes in the shape of the simulated reststrahlen peak are observed for changes in the high frequency dielectric constant, the phonon damping constant, the phonon frequencies and “thickness” of damaged surface layer.

  6. A Solar Reflectance Method for Retrieving Cloud Optical Thickness and Droplet Size Over Snow and Ice Surfaces

    Science.gov (United States)

    Platnick, S.; Li, J. Y.; King, M. D.; Gerber, H.; Hobbs, P. V.

    1999-01-01

    Cloud optical thickness and effective radius retrievals from solar reflectance measurements are traditionally implemented using a combination of spectral channels that are absorbing and non-absorbing for water particles. Reflectances in non-absorbing channels (e.g., 0.67, 0.86, 1.2 micron spectral window bands) are largely dependent on cloud optical thickness, while longer wavelength absorbing channels (1.6, 2. 1, and 3.7 micron window bands) provide cloud particle size information. Cloud retrievals over ice and snow surfaces present serious difficulties. At the shorter wavelengths, ice is bright and highly variable, both characteristics acting to significantly increase cloud retrieval uncertainty. In contrast, reflectances at the longer wavelengths are relatively small and may be comparable to that of dark open water. A modification to the traditional cloud retrieval technique is devised. The new algorithm uses only a combination of absorbing spectral channels for which the snow/ice albedo is relatively small. Using this approach, retrievals have been made with the MODIS Airborne Simulator (MAS) imager flown aboard the NASA ER-2 from May - June 1998 during the Arctic FIRE-ACE field deployment. Data from several coordinated ER-2 and University of Washington CV-580 in situ aircraft observations of liquid water stratus clouds are examined. MAS retrievals of optical thickness, droplet effective radius, and liquid water path are shown to be in good agreement with the in situ measurements. The initial success of the technique has implications for future operational satellite cloud retrieval algorithms in polar and wintertime regions.

  7. An investigation of the reflection of low energy electrons from the surfaces of layered transition metal dichalcogenides

    International Nuclear Information System (INIS)

    Smith, A.E.; Mohamed, M.H.; Wohlenberg, T.; Johnson, E.; Chadderton, L.T.; Moeller, P.J.

    1980-01-01

    Experimental measurements, using the total current spectroscopy (TCS) technique, on the energy dependence of the reflection of low energy electrons from clean surfaces of layered transition metal dichalcogenides are reported for the molybdenum semiconductor compounds 2H-MoS 2 and 2H-MoSe 2 . A simple model calculation involving both elastic and inelastic scattering is presented and correspondence established with the experimental spectra. In this picture information on the electronic band structure of the materials can then be extracted from the single particle component of the inelastic scattering. The model is extended to show that a feature in the 2H-MoS 2 experimental spectrum may be attributed to the excitation of an intermediate plasmon. (Auth.)

  8. Shear-wave seismic reflection imaging and impedance inversion for a near-surface point-bar

    Science.gov (United States)

    Benton, N. W.; Morrison, M.; Lorenzo, J. M.; Odom, B.; Clift, P. D.; Olson, E.; Gostic, A.

    2017-12-01

    Imaging and inversion of SH-waves are useful to detect, map, and quantitatively characterize near-surface point-bar strata. We conduct a horizontally-polarized (SH) reflection survey across and along a near-surface (9 - 40 m) downstream point-bar. We invert for shear-impedance profiles and correlate our interpretation to electrical conductivity (EC) logs in adjacent wells to study the internal architecture and lithology of point-bars. We acquire two common-midpoint (CMP) SH-wave seismic reflection lines at False River (Point Coupee Parish, Louisiana). A 104 m long seismic line (L1) is oriented orthogonal (NW - SE) to point-bar strike. A second line (L2) is 48 m long and set parallel to point-bar strike (NE - SW). Two EC wells lie 33 m apart. Both wells are parallel with respect to the L1 survey and offset from it by 15 m. EC log measurements range from 1 - 25 m depth. Interference of Love-waves prevents seismic imaging at depths less than 9 m. The L1 and L2 data sets are inverted for shear-impedance using a model-based band-limited impedance (BLIMP) algorithm that incorporates a low-frequency velocity model. This model is also used for the depthing processing. The L1 cross-section shows coherent dipping reflection events ( 4 - 7º) from 0.15 - 0.35 s (10 - 40 m). The corresponding shear-impedance profile also reveals coherent and dipping impedance contrasts that grow in magnitude with increasing depth. The L2 cross-section shows comparatively less dip ( 1º) as well as sharper and shallower continuity of reflection events (0.1 - 0.28 s TWT or 9 - 25 m). Depth-converted (TVD) seismic amplitudes and impedance values correlate to near-surface point-bar geology via superposition of log data. The first well (W5) shows distinct EC local maxima (+50 - 70 mS/m) at 14.5 and 15.5 m depth that correlate well with the seismic amplitudes and impedance values from both L1 and L2 data sets. The second well (W7) shows comparatively lower local maxima (+40 - 60 mS/m) but at greater

  9. Characterization of the Vajont landslide (North-Eastern Italy) by means of reflection and surface wave seismics

    Science.gov (United States)

    Petronio, Lorenzo; Boaga, Jacopo; Cassiani, Giorgio

    2016-05-01

    The mechanisms of the disastrous Vajont rockslide (North-Eastern Italy, October 9, 1963) have been studied in great detail over the past five decades. Nevertheless, the reconstruction of the rockslide dynamics still presents several uncertainties, including those related to the accurate estimation of the actual landslide mass. This work presents the results of a geophysical characterization of the Vajont landslide body in terms of material properties and buried geometry. Both aspects add new information to the existing dataset and will help a better understanding of the rockslide failure mechanisms and dynamics. In addition, some general considerations concerning the intricacies of landslide characterization can be drawn, with due attention to potential pitfalls. The employed techniques are: (i) high resolution P-wave reflection, (ii) high resolution SH-wave reflection, (iii) controlled source surface wave analysis. We adopted as a seismic source a vibrator both for P waves and SH waves, using vertical and horizontal geophones respectively. For the surface wave seismic survey we used a heavy drop-weight source and low frequency receivers. Despite the high noise level caused by the fractured conditions of the large rock body, a common situation in landslide studies, we managed to achieve a satisfying imaging quality of the landslide structure thanks to the large number of active channels, the short receiver interval and the test of appropriate seismic sources. The joint use of different seismic techniques help focus the investigation on the rock mass mechanical properties. Results are in good agreement with the available borehole data, the geological sections and the mechanical properties of the rockmass estimated by other studies. In general the proposed approach is likely to be applicable successfully to similar situations where scattering and other noise sources are a typical bottleneck to geophysical data acquisition on landslide bodies.

  10. An Algorithm for the Retrieval of 30-m Snow-Free Albedo from Landsat Surface Reflectance and MODIS BRDF

    Science.gov (United States)

    Shuai, Yanmin; Masek, Jeffrey G.; Gao, Feng; Schaaf, Crystal B.

    2011-01-01

    We present a new methodology to generate 30-m resolution land surface albedo using Landsat surface reflectance and anisotropy information from concurrent MODIS 500-m observations. Albedo information at fine spatial resolution is particularly useful for quantifying climate impacts associated with land use change and ecosystem disturbance. The derived white-sky and black-sky spectral albedos maybe used to estimate actual spectral albedos by taking into account the proportion of direct and diffuse solar radiation arriving at the ground. A further spectral-to-broadband conversion based on extensive radiative transfer simulations is applied to produce the broadband albedos at visible, near infrared, and shortwave regimes. The accuracy of this approach has been evaluated using 270 Landsat scenes covering six field stations supported by the SURFace RADiation Budget Network (SURFRAD) and Atmospheric Radiation Measurement Southern Great Plains (ARM/SGP) network. Comparison with field measurements shows that Landsat 30-m snow-free shortwave albedos from all seasons generally achieve an absolute accuracy of +/-0.02 - 0.05 for these validation sites during available clear days in 2003-2005,with a root mean square error less than 0.03 and a bias less than 0.02. This level of accuracy has been regarded as sufficient for driving global and regional climate models. The Landsat-based retrievals have also been compared to the operational 16-day MODIS albedo produced every 8-days from MODIS on Terra and Aqua (MCD43A). The Landsat albedo provides more detailed landscape texture, and achieves better agreement (correlation and dynamic range) with in-situ data at the validation stations, particularly when the stations include a heterogeneous mix of surface covers.

  11. The Dark Matter Time Projection Chamber 4Shooter directional dark matter detector: Calibration in a surface laboratory

    International Nuclear Information System (INIS)

    Battat, James B.R.; Deaconu, Cosmin; Druitt, Gabriela; Eggleston, Richard; Fisher, Peter; Giampa, Pietro; Gregoric, Vincent; Henderson, Shawn; Jaegle, Igal; Lawhorn, Jay; Lopez, Jeremy P.; Monroe, Jocelyn; Recine, Kristen A.; Strandberg, Adam; Tomita, Hidefumi; Vahsen, Sven; Wellenstein, Hermann

    2014-01-01

    The 4Shooter is a prototype dark matter detector built by the Dark Matter Time Projection Chamber (DMTPC) collaboration. The aim of the collaboration is to observe dark matter with directional sensitivity by measuring the recoil directions of nuclei struck by dark matter particles. The 4Shooter is a single time projection chamber containing CF 4 gas, with both optical (CCD and photomultiplier tube) and charge readout. This paper describes the 4Shooter and presents results from the commissioning of the detector in a surface laboratory

  12. Highly reflective liquid mirrors: exploring the effects of localized surface plasmon resonance and the arrangement of nanoparticles on metal liquid-like films.

    Science.gov (United States)

    Yen, Yu-Ting; Lu, Tai-Yen; Lee, Yang-Chun; Yu, Chen-Chieh; Tsai, Yin-Chih; Tseng, Yi-Chuan; Chen, Hsuen-Li

    2014-03-26

    In this paper, we describe a high-reflectance liquid mirror prepared from densely packed silver nanoparticles (AgNPs) of two different sizes. We controlled the particle size during the synthetic process by controlling the temperature. Varying the concentration of the ligand also allowed us to optimize the arrangement of the AgNPs to achieve liquid mirrors exhibiting high specular reflectance. Scanning electron microscopy and atomic force microscopy confirmed that the particles of the liquid mirror were well-packed with an interparticle distance of merely 2 nm; thus, the interstices and surface roughness of the NPs were effectively minimized. As a result of decreased scattering loss, the reflectance in the shorter wavelength regime was increased effectively. The AgNP film was also sufficiently thick to reflect the light in the longer wavelength regime. In addition, we used three-dimensional finite-difference time domain simulations and experimental measurements to investigate the relationship between the localized surface plasmon resonance (LSPR) and the specular reflection of the liquid mirrors. By changing the packing density of the AgNPs, we found that the LSPR effect could yield either a specular reflection peak or dip at the LSPR wavelengths in the reflection spectra of the liquid mirrors. Relative to previously reported liquid mirrors, the reflectance of our system is obviously much greater, especially in the shorter wavelength regime. The average reflectance in the range from 400 to 1000 nm could reach 77%, comparable with that of mercury-based liquid mirrors.

  13. Evidence for surface water ice in the lunar polar regions using reflectance measurements from the Lunar Orbiter Laser Altimeter and temperature measurements from the Diviner Lunar Radiometer Experiment

    Science.gov (United States)

    Fisher, Elizabeth A.; Lucey, Paul G.; Lemelin, Myriam; Greenhagen, Benjamin T.; Siegler, Matthew A.; Mazarico, Erwan; Aharonson, Oded; Williams, Jean-Pierre; Hayne, Paul O.; Neumann, Gregory A.; Paige, David A.; Smith, David E.; Zuber, Maria T.

    2017-08-01

    We find that the reflectance of the lunar surface within 5° of latitude of the South Pole increases rapidly with decreasing temperature, near ∼110 K, behavior consistent with the presence of surface water ice. The North polar region does not show this behavior, nor do South polar surfaces at latitudes more than 5° from the pole. This South pole reflectance anomaly persists when analysis is limited to surfaces with slopes less than 10° to eliminate false detection due to the brightening effect of mass wasting, and also when the very bright south polar crater Shackleton is excluded from the analysis. We also find that south polar regions of permanent shadow that have been reported to be generally brighter at 1064 nm do not show anomalous reflectance when their annual maximum surface temperatures are too high to preserve water ice. This distinction is not observed at the North Pole. The reflectance excursion on surfaces with maximum temperatures below 110 K is superimposed on a general trend of increasing reflectance with decreasing maximum temperature that is present throughout the polar regions in the north and south; we attribute this trend to a temperature or illumination-dependent space weathering effect (e.g. Hemingway et al., 2015). We also find a sudden increase in reflectance with decreasing temperature superimposed on the general trend at 200 K and possibly at 300 K. This may indicate the presence of other volatiles such as sulfur or organics. We identified and mapped surfaces with reflectances so high as to be unlikely to be part of an ice-free population. In this south we find a similar distribution found by Hayne et al. (2015) based on UV properties. In the north a cluster of pixels near that pole may represent a limited frost exposure.

  14. Application of the Self Calibrating Emissivity and/or Transmissivity Independent Multiwavelength Pyrometer in an Intense Ambient Radiation Environment

    Science.gov (United States)

    Ng, Daniel

    1996-01-01

    The NASA self calibrating multiwavelength pyrometer is a recent addition to the list of pyrometers used in remote temperature measurement in research and development. The older one-color, two-color, and the disappearing filament pyrometers, as well as the multicolor and early multiwavelength pyrometers, all do not operate successfully in situations in which strong ambient radiation coexists with radiation originating from the measured surface. In such situations radiation departing from the target surface arrives at the pyrometer together with radiation coming from another source either directly or through reflection. Unlike the other pyrometers, the self calibrating multiwavelength pyrometer can still calibrate itself and measure the temperatures in this adverse environment.

  15. One-chip biosensor for simultaneous disease marker/calibration substance measurement in human urine by electrochemical surface plasmon resonance method.

    Science.gov (United States)

    Nakamoto, Kohei; Kurita, Ryoji; Niwa, Osamu

    2010-12-15

    We have developed a miniaturized electrochemical surface plasmon resonance biosensor for measuring two biomolecules that have very different molecular sizes, one is transferrin (MW=75 kDa) as a disease marker protein, the other is creatinine (MW=113) as a calibration marker for the accurate measurement of human urinary samples. The sensor has a PDMS based microchannel that is 2 mm wide and 20 μm deep. Two gold films were integrated in the microchannel; one was modified with anti-transferrin antibody for immuno-reaction, and the other was modified with osmium-poly-vinylpyridine wired horseradish peroxidase (Os-gel-HRP). We further immobilized a tri-enzyme layer of creatininase, creatinase and sarcosine oxidase in order to measure creatinine by converting it to hydrogen peroxide in the upstream channel. We measured the transferrin concentration from the refractive index change involved in an immuno-complex formation, and we were simultaneously able to measure creatinine by employing the refractive index change in the Os-gel-HRP caused by oxidation with the hydrogen peroxide produced from creatinine by the tri-enzyme. The effects of ascorbic acid and uric acid in urine samples were sufficiently eliminated by adding ascorbate oxidase and uricase to the urine samples during sampling. We were able to measure two analyte concentrations within 15 min by one simple injection of 50 μL of diluted human urine into our sensor. The detectable transferrin and creatinine ranges were 20 ng/mL to 10 μg/mL, and 10 μM to 10 mM, respectively, which are sufficient levels for clinical tests. Finally, we compared the results obtained using our sensor with those obtained with a conventional immunoassay and the Jaffe method. We obtained a similar trend that can reduce the fluctuation in the urinary transferrin concentration from three different samples by calibrating the creatinine concentration. Copyright © 2010 Elsevier B.V. All rights reserved.

  16. Surface Gradient Integrated Profiler for X-ray and EUV Optics--Calibration of the rotational angle error of the rotary encoders

    International Nuclear Information System (INIS)

    Higashi, Yasuo; Kume, Tatsuya; Enami, Kazuhiro; Ueno, Kenji; Mori, Yuzo; Takaie, Yuichi; Endo, Katsuyoshi; Yamauchi, Kazuto; Yamamura, Kazuya; Sano, Yasuhisa

    2007-01-01

    A new ultraprecision profiler has been developed to measure for example asymmetric and aspheric profiles. The principle of our measuring method is that the normal vector at each point on the surface is determined by making the incident light beam on the mirror surface and the reflected beam at that point coincident. The gradient at each point is calculated from the normal vector, and the surface profile is then obtained by integrating the gradients. The measuring instrument was designed in accordance with the above principle for the measuring method and is called Surface Gradient Integrated Profiler (SGIP). In the design, four ultraprecision goniometers were applied to adjust the light axis for the normal vector measurement. These goniostages make it possible to attain an angular resolution of 0.018 μ radian by electrically dividing a pulse of the rotary encoder. The surface gradients are determined only by the rotational angle of goniometers. Thus in the measuring instrument, the most important factor is the accuracy of the normal vectors measured by the goniometers. To attain an accuracy of 0.1 μ radian, we developed a system for correcting the rotational angle error of the goniometers in which the trigonometric measuring method is utilized for geometrical angle determination

  17. Determination of ultra trace contaminants on silicon wafer surfaces using total-reflection X-ray fluorescence TXRF 'state-of-the-art'

    Science.gov (United States)

    Pahlke, S.; Fabry, L.; Kotz, L.; Mantler, C.; Ehmann, T.

    2001-11-01

    In a well balanced system of highly motivated, well trained personnel and automated equipment, pure reagents and bulk media, cleanrooms and integrated data management, total-reflection X-ray fluorescence (TXRF) can and must contribute to quality assurance and process stability, support and canalize creative engineering by continuous learning about materials and processes. TXRF has the advantage of controlled one-point calibration, a linear dynamic range of three orders of magnitude, high grade of automation in operation and data management, high up-time, and a simple control of data plausibility.

  18. Surface cleanliness measurement procedure

    Science.gov (United States)

    Schroder, Mark Stewart; Woodmansee, Donald Ernest; Beadie, Douglas Frank

    2002-01-01

    A procedure and tools for quantifying surface cleanliness are described. Cleanliness of a target surface is quantified by wiping a prescribed area of the surface with a flexible, bright white cloth swatch, preferably mounted on a special tool. The cloth picks up a substantial amount of any particulate surface contamination. The amount of contamination is determined by measuring the reflectivity loss of the cloth before and after wiping on the contaminated system and comparing that loss to a previous calibration with similar contamination. In the alternative, a visual comparison of the contaminated cloth to a contamination key provides an indication of the surface cleanliness.

  19. Reflectance model for densely packed media: Estimates of the surface properties of the high-albedo satellites of Saturn

    Science.gov (United States)

    Tishkovets, V. P.; Petrova, E. V.

    2017-07-01

    Interpretation of photometric and polarimetric observations of atmosphereless celestial bodies faces the problems connected with both the insufficient accuracy and level of details in groundbased observations and the current state of the theory of the multiple scattering of light. In application to sparse media, where the electromagnetic waves, propagating between the scatterers, can be considered as spherical (the socalled far-field approximation), this theory is rather well developed for both the diffuse and coherent components of the scattered radiation. In this paper, we show that this theory can be also successfully applied to the measurements of polarization of light scattered by densely packed, though nonabsorbing or weakly absorbing, media. For this purpose, we calculated the models for a semi-infinite layer of the medium composed of randomly oriented clusters of spherical particles and compared them with the data of laboratory and astronomical measurements. The potential of the present approach is illustrated by an example of the interpretation of the polarization measurements of the ice satellites of Saturn—Rhea and Enceladus—which allowed some properties of the surface of these celestial bodies to be estimated. In particular, the ratio of the surface area that makes no contribution to the negative polarization of light reflected at small phase angles to the area producing the negative polarization branch was found. Under the assumption of the same albedo of these areas, this ratio turned out to be 3.31-3.66 and 1.7-3.8 for Rhea and Enceladus, respectively. For Enceladus, it is difficult to obtain a sufficiently narrow range of the estimated parameters, since the number of measurement points in the phase dependence of polarization of this satellite is small. For the surface of Rhea, the estimated packing density of particles, participating in the opposition effects, is approximately 15%, while their smallest size is of the order of the wavelength of

  20. Development of new maskless manufacturing method for anti-reflection structure and application to large-area lens with curved surface

    Science.gov (United States)

    Yamamoto, Kazuya; Takaoka, Toshimitsu; Fukui, Hidetoshi; Haruta, Yasuyuki; Yamashita, Tomoya; Kitagawa, Seiichiro

    2016-03-01

    In general, thin-film coating process is widely applied on optical lens surface as anti-reflection function. In normal production process, at first lens is manufactured by molding, then anti-reflection is added by thin-film coating. In recent years, instead of thin-film coating, sub-wavelength structures adding on surface of molding die are widely studied and development to keep anti-reflection performance. As merits, applying sub-wavelength structure, coating process becomes unnecessary and it is possible to reduce man-hour costs. In addition to cost merit, these are some technical advantages on this study. Adhesion of coating depends on material of plastic, and it is impossible to apply anti-reflection function on arbitrary surface. Sub-wavelength structure can solve both problems. Manufacturing method of anti-reflection structure can be divided into two types mainly. One method is with the resist patterning, and the other is mask-less method that does not require patterning. What we have developed is new mask-less method which is no need for resist patterning and possible to impart an anti-reflection structure to large area and curved lens surface, and can be expected to apply to various market segments. We report developed technique and characteristics of production lens.

  1. Particle Fabrication Using Inkjet Printing onto Hydrophobic Surfaces for Optimization and Calibration of Trace Contraband Detection Sensors

    Directory of Open Access Journals (Sweden)

    Greg Gillen

    2015-11-01

    Full Text Available A method has been developed to fabricate patterned arrays of micrometer-sized monodisperse solid particles of ammonium nitrate on hydrophobic silicon surfaces using inkjet printing. The method relies on dispensing one or more microdrops of a concentrated aqueous ammonium nitrate solution from a drop-on-demand (DOD inkjet printer at specific locations on a silicon substrate rendered hydrophobic by a perfluorodecytrichlorosilane monolayer coating. The deposited liquid droplets form into the shape of a spherical shaped cap; during the evaporation process, a deposited liquid droplet maintains this geometry until it forms a solid micrometer sized particle. Arrays of solid particles are obtained by sequential translation of the printer stage. The use of DOD inkjet printing for fabrication of discrete particle arrays allows for precise control of particle characteristics (mass, diameter and height, as well as the particle number and spatial distribution on the substrate. The final mass of an individual particle is precisely determined by using gravimetric measurement of the average mass of solution ejected per microdrop. The primary application of this method is fabrication of test materials for the evaluation of spatially-resolved optical and mass spectrometry based sensors used for detecting particle residues of contraband materials, such as explosives or narcotics.

  2. Calibration of a PHREEQC-based geochemical model to predict surface water discharge from an operating uranium mill in the Athabasca Basin

    International Nuclear Information System (INIS)

    Mahoney, J.; Ryan, F.

    2014-01-01

    calibration used annual water balances and compositions from 2000 to 2011. The calibration indicated that a simple mixing approach could explain the behavior of conservative elements such as sodium, potassium and chloride. For calcium and sulfate, the precipitation of gypsum (CaSO4•2H2O) may occur in the holding ponds. This lowers the calcium and sulfate discharge from this source term, but also improves the fit in the downstream lakes. Even though most of the major ions are conserved and attenuated through dilution, many of the chemicals of concern such as molybdenum, uranium and arsenic have lower measured concentrations than predicted by the initial mixing models. Attenuation processes beyond simple dilution and typically related to mineral precipitation or surface complexation are responsible for these drops in concentrations. This modeling effort provides insights into the geochemical behavior of trace metals that would not be readily apparent without the model. (author)

  3. A Modern Sr/Ca-δ18O-Sea Surface Temperature Calibration for Isopora Corals in the Great Barrier Reef

    Science.gov (United States)

    Brenner, L. D.; Linsley, B. K.; Potts, D. C.

    2014-12-01

    Most coral-based paleoceanographic studies have used massive colonies of Porites or Faviidae, due to their long, continuously accreted skeletal records and sub-annual resolution, but other sub-massive corals provide an untapped resource. The genus Isopora is a dominant reef builder in some high-energy environments in the tropical western Pacific, and was a major component of cores recovered on IODP Leg 325 off the Great Barrier Reef (GBR). Despite its abundance, Isopora remains largely unexplored and hence underutilized in paleoceanographic studies. We present a modern Sr/Ca-δ18O-Sea Surface Temperature (SST) calibration of modern Isopora corals (n=3) collected from inner and outer reef locations ranging from 1-13m depth by Heron Island in the southern GBR in 2012. Pairing the Isopora Sr/Ca record with monthly SST yielded an average relationship of SST=-11.48×(Sr/Ca)+131.1 (r2 = 0.42-0.78). The Sr/Ca sensitivity of -0.087 mmol/mol/°C is similar to the sensitivity for Porites that was corrected for tissue layer smoothing effects determined by Gagan et al. (2012). The similarity between our Sr/Ca-SST sensitivity and the corrected sensitivity for Porites suggests tissue layer effects are minimal in Isopora. The mean annual SST amplitude recorded by the corals from 2008-2011 (full annual cycles) was 5.3°C and the average δ18O annual cycle of 1.1‰ approximates that expected if salinity had little effect on coral δ18O, assuming a previously established conversion of -0.23‰ (δ18O)/°C for biogenic aragonite. The average annual salinity amplitude of 0.3 in gridded data from around Heron Island supports our conclusion that δ18O variability is forced almost completely by SST. This modern Sr/Ca-SST calibration will expand the paleoceanographic utility of Isopora and, by assisting interpretation of Sr/Ca data from fossil corals collected during IODP 325, will better constrain the timing and magnitude of sea level changes and surface conditions since the Last

  4. Reflectance Modeling

    Science.gov (United States)

    Smith, J. A.; Cooper, K.; Randolph, M.

    1984-01-01

    A classical description of the one dimensional radiative transfer treatment of vegetation canopies was completed and the results were tested against measured prairie (blue grama) and agricultural canopies (soybean). Phase functions are calculated in terms of directly measurable biophysical characteristics of the canopy medium. While the phase functions tend to exhibit backscattering anisotropy, their exact behavior is somewhat more complex and wavelength dependent. A Monte Carlo model was developed that treats soil surfaces with large periodic variations in three dimensions. A photon-ray tracing technology is used. Currently, the rough soil surface is described by analytic functions and appropriate geometric calculations performed. A bidirectional reflectance distribution function is calculated and, hence, available for other atmospheric or canopy reflectance models as a lower boundary condition. This technique is used together with an adding model to calculate several cases where Lambertian leaves possessing anisotropic leaf angle distributions yield non-Lambertian reflectance; similar behavior is exhibited for simulated soil surfaces.

  5. Application of Sol-Gel Method as a Protective Layer on a Specular Reflective Surface for Secondary Reflector in a Solar Receiver

    Energy Technology Data Exchange (ETDEWEB)

    Afrin, Samia; Dagdelen, John; Ma, Zhiwen; Kumar, Vinod

    2017-01-01

    Highly-specular reflective surfaces that can withstand elevated-temperatures are desirable for many applications including reflective heat shielding in solar receivers and secondary reflectors, which can be used between primary concentrators and heat collectors. A high-efficiency, high-temperature solar receiver design based on arrays of cavities needs a highly-specular reflective surface on its front section to help sunlight penetrate into the absorber tubes for effective flux spreading. Since this application is for high-temperature solar receivers, this surface needs to be durable and to maintain its optical properties through the usable life. Degradation mechanisms associated with elevated temperatures and thermal cycling, which include cracking, delamination, corrosion/oxidation, and environmental effects, could cause the optical properties of surfaces to degrade rapidly in these conditions. Protected mirror surfaces for these applications have been tested by depositing a thin layer of SiO2 on top of electrodeposited silver by means of the sol-gel method. To obtain an effective thin film structure, this sol-gel procedure has been investigated extensively by varying process parameters that affect film porosity and thickness. Endurance tests have been performed in a furnace at 150 degrees C for thousands of hours. This paper presents the sol-gel process for intermediate-temperature specular reflective coatings and provides the long-term reliability test results of sol-gel protected silver-coated surfaces.

  6. Development of an Operational Calibration Methodology for the Landsat Thermal Data Archive and Initial Testing of the Atmospheric Compensation Component of a Land Surface Temperature (LST Product from the Archive

    Directory of Open Access Journals (Sweden)

    Monica Cook

    2014-11-01

    Full Text Available The Landsat program has been producing an archive of thermal imagery that spans the globe and covers 30 years of the thermal history of the planet at human scales (60–120 m. Most of that archive’s absolute radiometric calibration has been fixed through vicarious calibration techniques. These calibration ties to trusted values have often taken a year or more to gather sufficient data and, in some cases, it has been over a decade before calibration certainty has been established. With temperature being such a critical factor for all living systems and the ongoing concern over the impacts of climate change, NASA and the United States Geological Survey (USGS are leading efforts to provide timely and accurate temperature data from the Landsat thermal data archive. This paper discusses two closely related advances that are critical steps toward providing timely and reliable temperature image maps from Landsat. The first advance involves the development and testing of an autonomous procedure for gathering and performing initial screening of large amounts of vicarious calibration data. The second advance discussed in this paper is the per-pixel atmospheric compensation of the data to permit calculation of the emitted surface radiance (using ancillary sources of emissivity data and the corresponding land surface temperature (LST.

  7. Calibration of the instrumental polarization in LEST.

    Science.gov (United States)

    Stenflo, J. O.

    A method to calibrate the instrumental polarization of LEST (i.e., of the optics in front of the polarization and analysis package at the LEST secondary focus) is described and analysed. A laser sends a beam from the LEST observing room at ground level backwards through the telescope. The modulated return beam that has been reflected at the 2.4 m entrance window is received by the detector system at the end focus in the LEST observing room. Because of a wedge in the entrance window the reflections at the front and back window surfaces may be examined separately. The detected laser beam signals at the three AC frequencies are recorded as functions of the position angle of the modulator package at the LEST secondary focus. Aided by a theorem that is proven in the present paper, the information recorded by the detector system allows all unknowns of the instrumental polarization to be fully determined.

  8. Radiation reflection from star surface reveals the mystery of interpulse shift and appearance of high frequency components in the Crab pulsar

    Science.gov (United States)

    Kontorovich, V. M.; Trofymenko, S. V.

    2017-12-01

    A new mechanism of radiation emission in the polar gap of a pulsar is discussed. It is based on the curvature radiation which is emitted by positrons moving towards the surface of neutron star along field lines of the inclined magnetic field and reflects from the surface. This mechanism explains the mystery of the interpulse shift and appearance of additional components in the emission of Crab pulsar at high frequencies discovered by Moffett and Hankins twenty years ago. We discuss coherence, energy flux and spectrum of the reflected radiation, appearance and disappearance of the interpulse position shift with the frequency increase. It is also possible that a nonlinear reflection (stimulated scattering) from the star surface is observed in the form of HF components. The frequency drift of these components, discovered by Hankins, Jones and Eilek, is discussed. The nonlinear reflection is associated with “Wood’s anomaly” at the diffracted waves grazing along the star surface. Two components can arise due to slow and fast waves which are present in the magnetospheric plasma. The possible scheme of their appearance due to birefringence at the reflection is also proposed.

  9. Self-calibrated active pyrometer for furnace temperature measurements

    Science.gov (United States)

    Woskov, Paul P.; Cohn, Daniel R.; Titus, Charles H.; Surma, Jeffrey E.

    1998-01-01

    Pyrometer with a probe beam superimposed on its field-of-view for furnace temperature measurements. The pyrometer includes a heterodyne millimeter/sub-millimeter-wave or microwave receiver including a millimeter/sub-millimeter-wave or microwave source for probing. The receiver is adapted to receive radiation from a surface whose temperature is to be measured. The radiation includes a surface emission portion and a surface reflection portion which includes the probe beam energy reflected from the surface. The surface emission portion is related to the surface temperature and the surface reflection portion is related to the emissivity of the surface. The simultaneous measurement of surface emissivity serves as a real time calibration of the temperature measurement. In an alternative embodiment, a translatable base plate and a visible laser beam allow slow mapping out of interference patterns and obtaining peak values therefor. The invention also includes a waveguide having a replaceable end portion, an insulating refractory sleeve and/or a source of inert gas flow. The pyrometer may be used in conjunction with a waveguide to form a system for temperature measurements in a furnace. The system may employ a chopper or alternatively, be constructed without a chopper. The system may also include an auxiliary reflector for surface emissivity measurements.

  10. Derivation of Land Surface Albedo at High Resolution by Combining HJ-1A/B Reflectance Observations with MODIS BRDF Products

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2014-09-01

    Full Text Available Land surface albedo is an essential parameter for monitoring global/regional climate and land surface energy balance. Although many studies have been conducted on global or regional land surface albedo using various remote sensing data over the past few decades, land surface albedo product with a high spatio–temporal resolution is currently very scarce. This paper proposes a method for deriving land surface albedo with a high spatio–temporal resolution (space: 30 m and time: 2–4 days. The proposed method works by combining the land surface reflectance data at 30 m spatial resolution obtained from the charge-coupled devices in the Huanjing-1A and -1B (HJ-1A/B satellites with the Moderate Resolution Imaging Spectroradiometer (MODIS land surface bidirectional reflectance distribution function (BRDF parameters product (MCD43A1, which is at a spatial resolution of 500 m. First, the land surface BRDF parameters for HJ-1A/B land surface reflectance with a spatial–temporal resolutions of 30 m and 2–4 day are calculated on the basis of the prior knowledge from the MODIS BRDF product; then, the calculated high resolution BRDF parameters are integrated over the illuminating/viewing hemisphere to produce the white- and black-sky albedos at 30 m resolution. These results form the basis for the final land surface albedo derivation by accounting for the proportion of direct and diffuse solar radiation arriving at the ground. The albedo retrieved by this novel method is compared with MODIS land surface albedo products, as well as with ground measurements. The results show that the derived land surface albedo during the growing season of 2012 generally achieved a mean absolute accuracy of ±0.044, and a root mean square error of 0.039, confirming the effectiveness of the newly proposed method.

  11. Development and featuring of hemispherical photomultipliers for cosmic ray detection - calibration of surface detectors and analysis of horizontal showers at the Pierre Auger Observatory

    International Nuclear Information System (INIS)

    Dornic, D.

    2006-09-01

    The large photomultipliers (PMT) are currently used in astro-particle and neutrino experiments where they have to detect low levels of light. We have studied and characterised large PMTs developed by the PHOTONIS Group Company. The first part of this thesis is dedicated to the full characterization of two types of multipliers currently used in large PMTs. Then, we present results of a new photocathode process, applied on the XPI805 (PMT used in the Pierre Auger Observatory) in order to improve the quantum efficiency. Finally, we study the PMT diameter influence on main parameters (5, 8 and 10 inches). The second part is devoted to the study of the water Cerenkov tank (WCD) response to the shower particles and the horizontal air showers analysis with the Pierre Auger Observatory. The main parameters of a WCD simulation developed in the Auger IPN group were calibrated with several measurements on vertical and inclined muons, performed on dedicated test tanks. The kind of detector used in the surface detector allows detecting very inclined events with a good sensitivity (zenith angle superior to 70 degrees). We have established specific methods to analyze these events (selection and reconstruction). These methods were applied to the Auger data in order to obtain the energy spectrum of the horizontal events. Finally, we detailed two methods to test directly the hadronic models predictions by studying the air showers muonic component. (author)

  12. Surface characterization of selected polymer thin films by total-reflection x-ray fluorescence spectroscopy and x-ray reflectivity

    International Nuclear Information System (INIS)

    Innis, Vallerie Ann A.

    2006-01-01

    Development of available x-ray characterizations tools for grazing incidence techniques was done to be able to probe nano-size thin films. Alignment of a Philips x-ray powder diffractometer was improved to let it perform as an x-ray reflectometer. X-ray reflectometry was coupled with total-reflection x-ray fluorescence spectroscopy. Evaluation of the performance of this grazing incidence techniques was done by preparing polymer thin films of carboxymethylcellulose, carrageenan and polyvinylpyrrolidone (PVP). The thickness of the films were varied by varying the process parameters such as concentration, spin speed and spin time. Angle-dispersive total-reflection x-ray fluorescence spectroscopy profiles of three films showed film formation only in carrageenan and PVP. For both carrageenan and PVP, an increase in concentration yielded a corresponding increase in intensity of the fluorescent or scattered peaks. XRR profiles of carrageenan thin films yielded a mean value for the critical angle close to quartz substrate. Thickness measurements of the prepared carrageenan thin films showed that concentration was the main determinant for final film thickness over the other process parameters. Sulfur fluorescent intensity derived from the TXRF measurement showed a linear relationship with the measured thickness by XRR. For PVP, measured critical angle is lower than quartz. Poor adhesion of the polymer onto the substrate yielded a limited number of thickness measurements made from the XRR profiles. (Author)

  13. Testing and calibration of geodetic instruments

    Directory of Open Access Journals (Sweden)

    Marek Bajtala

    2007-06-01

    Full Text Available The problem of testing, verification and calibration of length-scales (electronic rangefinders and angle-scales (geodetic instruments. The calibration of coded levelling rods and the systemic calibration of digital levelling instruments. The calibration on linear comparative baseline in a terrain – the elaboration of measured data. The testing of universal measuring instruments in laboratory conditions - specific problems in testing of instruments with the passive reflection. Some knowledge about the calibration of horizontal circles of angle-measuring geodetic instruments.

  14. A modern Sr/Ca-δ18O-sea surface temperature calibration for Isopora corals on the Great Barrier Reef

    Science.gov (United States)

    Brenner, Logan D.; Linsley, Braddock K.; Potts, Donald C.

    2017-02-01

    Isopora (Acroporidae) is a genus of often encrusting, branching to submassive corals that are common in many shallow habitats on modern and fossil Indo-West Pacific reefs. Although abundant, Isopora is largely absent from paleoceanographic literature. The scarcity of large Porites and the abundance of Isopora retrieved from the Great Barrier Reef (GBR) on Integrated Ocean Drilling Program Expedition 325 focused paleoceanographic attention on Isopora. Here we provide the first independent high-resolution calibration of both Sr/Ca and δ18O for temperature analyses based on Isopora and demonstrate its consistency with Porites records. We developed modern skeletal Sr/Ca- and δ18O-sea surface temperature (SST) calibrations based on five modern Isopora colonies from Heron Island in the southern GBR. Pairing the coral Sr/Ca record with monthly SST data yielded Sr/Ca-SST sensitivities from -0.061 ± 0.004 (centered) to -0.083 ± 0.007 (raw) mmol/mol °C-1 based on reduced major axis regressions. These sensitivities are in the middle of the range of published Porites values and overlap most published values for Isopora, -0.075 ± 0.011 to -0.065 ± 0.011 mmol/mol °C-1. The δ18O-SST sensitivities range from -0.184 ± 0.014 (centered) to -0.185 ± 0.014 (raw) ‰ °C-1, assuming that all seasonal variation in δ18O was due to SST. These δ18O-SST sensitivities are smaller than the widely accepted value of -0.23‰ °C-1 for biogenic aragonite but are at the upper end of high-resolution Porites-defined sensitivities that are consistently less than the aforementioned established value. Our results validate the use of Isopora as an alternative source of paleoceanographic records in habitats where large massive Porites are scarce or absent.

  15. Development and Application of Sr/Ca-δ18O-Sea Surface Temperature calibrations for Last Glacial Maximum-Aged Isopora corals in the Great Barrier Reef

    Science.gov (United States)

    Brenner, L. D.; Linsley, B. K.; Potts, D. C.; Felis, T.; Mcgregor, H. V.; Gagan, M. K.; Inoue, M.; Tudhope, A. W.; Esat, T. M.; Thompson, W. G.; Tiwari, M.; Fallon, S.; Humblet, M.; Yokoyama, Y.; Webster, J.

    2016-12-01

    Isopora (Acroporidae) are sub-massive to massive corals found on most modern and fossil Indo-Pacific reefs. Despite their abundance, they are largely absent from the paleoceanographic literature but have the potential to provide proxy data where other commonly used corals, such as Porites, are sparse. The retrieval of Isopora fossils during International Ocean Discovery Program Leg 325 in the Great Barrier Reef (GBR) signaled the need to evaluate their possible paleoceanographic utility. We developed modern skeletal Sr/Ca- and δ18O-sea surface temperature (SST) calibrations for six modern Isopora colonies collected at Heron Island in the southern GBR. Pairing the coral Sr/Ca record with monthly SST data yielded Reduced Major Axis Sr/Ca- and δ18O-SST sensitivities of -0.054 mmol/mol/°C and -0.152 ‰/°C, respectively, falling within the range of published Porites values. We applied our Isopora-based regressions and previously published sensitivities from other species to a suite (n=37) of fossil samples collected from IODP 32. The calibrations produced a range of 3-7°C of warming, averaging 5°C, in the GBR from 22 ka to modern climate. This SST change is similar or slightly larger than other coral studies and larger than planktonic foraminifera Mg/Ca records. The planktonic Mg/Ca records from the Indonesian and Western Pacific Warm Pools indicate a warming of 3-3.5°C since 23ka (Linsley et al., 2010) while a fossil coral record from Tahiti indicates a warming of 3.2°C from 9.5ka to present (DeLong et al., 2010) and western Pacific coral records suggest a cooling of 5-6°C (Gagan et al., 2010; Guilderson et al., 1994: Beck et al., 1997), although these value might require rescaling (Gagan et al., 2012) resulting in slightly warmer temperature calculations. Our Isopora fossils from the GBR speak to the spatial heterogeneity of warming since the LGM and the continued need to develop more records for a more comprehensive understanding of the deglaciation.

  16. Calibration of surface roughness standards

    DEFF Research Database (Denmark)

    Thalmann, R.; Nicolet, A.; Meli, F.

    2016-01-01

    The key comparison EURAMET.L-K8.2013 on roughness was carried out in the framework of a EURAMET project starting in 2013 and ending in 2015. It involved the participation of 17 National Metrology Institutes from Europe, Asia, South America and Africa representing four regional metrology organisat...

  17. Effect of Hydrological Properties on the Energy Shares of Reflected Waves at the Surface of a Partially Saturated Porous Solid

    Directory of Open Access Journals (Sweden)

    Mahabir Barak

    2017-02-01

    Full Text Available In the present study, the reflection of inhomogeneous waves is investigated at the stress-free plane surface based on multiphase poroelasticity theory. The porous medium is considered as dissipative due to the presence of viscosity in pores fluid. Four inhomogeneous (i.e. different direction of propagation and attenuation reflected waves (three longitudinal and one shear exists due to an incident wave. By using the appropriate boundary conditions, closed-form analytical expressions for the reflection coeffcients are derived at the stress-free surface. These reflection coeffcients are used to drive the analytical expressions for the energy shares of various reflected inhomogeneous waves. In mathematical framework, the conservation of incident energy is confirmed by considering an interaction energy between two dissimilar waves. It validates that the numerical calculations are analytically correct. Finally, a numerical example is considered to study the effects of viscous cross-coupling, porosity, saturation of gas, pore-characteristics and wave frequency on the energy shares of various reflected inhomogeneous waves and depicted graphically.

  18. Radiometric calibration and atmospheric correction of satellite and aircraft data for FIFE

    Science.gov (United States)

    Goetz, Scott J.; Markham, Brian L.; Newcomer, Jeffery A.

    1992-01-01

    The satellite and aircraft radiometric calibration and atmospheric correction work carried out as part of the first International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) are summarized. A large volume (120 Gbytes) of radiometric data were acquired and derived from a number of different instruments on a variety of platforms. The same basic procedure was applied to each instrument: derive the most recent calibration coefficients for converting sensor counts to reflective spectral radiances; correct the radiances for earth-sun distance variations and incident solar spectral irradiance within the bandpass of each respective instrument channel at the top of the atmosphere; characterize the atmosphere for aerosols and absorbing gases; and derive apparent surface reflectance by correcting the exoatmospheric values for atmospheric attenuation. The same basic approach was used for surface temperature derivation. The results of this processing were verified by surface measurements, and corroborated by sensor intercomparisons.

  19. Reflectance spectroscopy of natural organic solids, iron sulfides and their mixtures as refractory analogues for Rosetta/VIRTIS' surface composition analysis of 67P/CG

    Science.gov (United States)

    Moroz, Lyuba V.; Markus, Kathrin; Arnold, Gabriele; Henckel, Daniela; Kappel, David; Schade, Ulrich; Rousseau, Batiste; Quirico, Eric; Schmitt, Bernard; Capaccioni, Fabrizio; Bockelee-Morvan, Dominique; Filacchione, Gianrico; Érard, Stéphane; Leyrat, Cedric; VIRTIS Team

    2016-10-01

    Analysis of 0.25-5 µm reflectance spectra provided by the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS) onboard Rosetta orbiter revealed that the surface of 67P/CG is dark from the near-UV to the IR and is enriched in refractory phases such as organic and opaque components. The broadness and complexity of the ubiquitous absorption feature around 3.2 µm suggest a variety of cometary organic constituents. For example, complex hydrocarbons (aliphatic and polycyclic aromatic) can contribute to the feature between 3.3 and 3.5 µm and to the low reflectance of the surface in the visible. Here we present the 0.25-5 µm reflectance spectra of well-characterized terrestrial hydrocarbon materials (solid oil bitumens, coals) and discuss their relevance as spectral analogues for a hydrocarbon part of 67P/CG's complex organics. However, the expected low degree of thermal processing of cometary hydrocarbons (high (H+O+N+S)/C ratios and low carbon aromaticities) suggests high IR reflectance, intense 3.3-3.5 µm absorption bands and steep red IR slopes that are not observed in the VIRTIS spectra. Fine-grained opaque refractory phases (e.g., iron sulfides, Fe-Ni alloys) intimately mixed with other surface components are likely responsible for the low IR reflectance and low intensities of absorption bands in the VIRTIS spectra of the 67P/CG surface. In particular, iron sulfides are common constituents of cometary dust, "cometary" chondritic IDPs, and efficient darkening agents in primitive carbonaceous chondrites. Their effect on reflectance spectra of an intimate mixture is strongly affected by grain size. We report and discuss the 0.25-5 µm reflectance spectra of iron sulfides (meteoritic troilite and several terrestrial pyrrhotites) ground and sieved to various particle sizes. In addition, we present reflectance spectra of several intimate mixtures of powdered iron sulfides and solid oil bitumens. Based on the reported laboratory data, we discuss the ability of

  20. Vapor phase treatment–total reflection X-ray fluorescence for trace elemental analysis of silicon wafer surface

    Energy Technology Data Exchange (ETDEWEB)

    Takahara, Hikari, E-mail: hikari@rigaku.co.jp [Rigaku Corp., 14-8 Akaoji-cho, Takatsuki, Osaka 569-1146 (Japan); Mori, Yoshihiro [Horiba Ltd., 2 Miyanohigashi, Kisshoin, Minami-ku, Kyoto 601-8510 (Japan); Shibata, Harumi [SUMCO Corporation, Seavance North, 1-2-1 Shibaura, Minato-ku, Tokyo 105-8634 (Japan); Shimazaki, Ayako [Toshiba Corporation, 8, Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan); Shabani, Mohammad B. [Mitsubishi Material Corporation, 1-297, Kitabukuro-cho, Omiya-ku, Saitama 330-8508 (Japan); Yamagami, Motoyuki [Rigaku Corp., 14-8 Akaoji-cho, Takatsuki, Osaka 569-1146 (Japan); Yabumoto, Norikuni [Analysis Atelier Co., 4-36-4, Yoyogi, Shibuya-ku, Tokyo 151-0053 (Japan); Nishihagi, Kazuo [Horiba Ltd., 2 Miyanohigashi, Kisshoin, Minami-ku, Kyoto 601-8510 (Japan); Gohshi, Yohichi [Tsukuba University, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8571 (Japan)

    2013-12-01

    Vapor phase treatment (VPT) was under investigation by the International Organization for Standardization/Technical Committee 201/Working Group 2 (ISO/TC201/WG2) to improve the detection limit of total reflection X-ray fluorescence spectroscopy (TXRF) for trace metal analysis of silicon wafers. Round robin test results have confirmed that TXRF intensity increased by VPT for intentional contamination with 5 × 10{sup 9} and 5 × 10{sup 10} atoms/cm{sup 2} Fe and Ni. The magnification of intensity enhancement varied greatly (1.2–4.7 in VPT factor) among the participating laboratories, though reproducible results could be obtained for average of mapping measurement. SEM observation results showed that various features, sizes, and surface densities of particles formed on the wafer after VPT. The particle morphology seems to have some impact on the VPT efficiency. High resolution SEM observation revealed that a certain number of dots with SiO{sub 2}, silicate and/or carbon gathered to form a particle and heavy metals, Ni and Fe in this study were segregated on it. The amount and shape of the residue should be important to control VPT factor. - Highlights: • This paper presents a summary of study results of VPT–TXRF using ISO/TC201/WG2. • Our goal is to analyze the trace metallic contamination on silicon wafer with concentrations below 1 × 10{sup 10} atoms/cm{sup 2}. • The efficiency and mechanism of VPT are discussed under several round robin tests and systematic studies.

  1. POLCAL - POLARIMETRIC RADAR CALIBRATION

    Science.gov (United States)

    Vanzyl, J.

    1994-01-01

    Calibration of polarimetric radar systems is a field of research in which great progress has been made over the last few years. POLCAL (Polarimetric Radar Calibration) is a software tool intended to assist in the calibration of Synthetic Aperture Radar (SAR) systems. In particular, POLCAL calibrates Stokes matrix format data produced as the standard product by the NASA/Jet Propulsion Laboratory (JPL) airborne imaging synthetic aperture radar (AIRSAR). POLCAL was designed to be used in conjunction with data collected by the NASA/JPL AIRSAR system. AIRSAR is a multifrequency (6 cm, 24 cm, and 68 cm wavelength), fully polarimetric SAR system which produces 12 x 12 km imagery at 10 m resolution. AIRSTAR was designed as a testbed for NASA's Spaceborne Imaging Radar program. While the images produced after 1991 are thought to be calibrated (phase calibrated, cross-talk removed, channel imbalance removed, and absolutely calibrated), POLCAL can and should still be used to check the accuracy of the calibration and to correct it if necessary. Version 4.0 of POLCAL is an upgrade of POLCAL version 2.0 released to AIRSAR investigators in June, 1990. New options in version 4.0 include automatic absolute calibration of 89/90 data, distributed target analysis, calibration of nearby scenes with calibration parameters from a scene with corner reflectors, altitude or roll angle corrections, and calibration of errors introduced by known topography. Many sources of error can lead to false conclusions about the nature of scatterers on the surface. Errors in the phase relationship between polarization channels result in incorrect synthesis of polarization states. Cross-talk, caused by imperfections in the radar antenna itself, can also lead to error. POLCAL reduces cross-talk and corrects phase calibration without the use of ground calibration equipment. Removing the antenna patterns during SAR processing also forms a very important part of the calibration of SAR data. Errors in the

  2. Influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter: Comparative exercise using data from the qualifying system for reflectance analysis working group of ICCP

    Science.gov (United States)

    Borrego, A.G.; Araujo, C.V.; Balke, A.; Cardott, B.; Cook, A.C.; David, P.; Flores, D.; Hamor-Vido, M.; Hiltmann, W.; Kalkreuth, W.; Koch, J.; Kommeren, C.J.; Kus, J.; Ligouis, B.; Marques, M.; Mendonca, Filho J.G.; Misz, M.; Oliveira, L.; Pickel, W.; Reimer, K.; Ranasinghe, P.; Suarez-Ruiz, I.; Vieth, A.

    2006-01-01

    The development of a qualifying system for reflectance analysis has been the scope of a working group within the International Committee for Coal and Organic Petrology (ICCP) since 1999, when J. Koch presented a system to qualify vitrinite particles according to their size, proximity to bright components and homogeneity of the surface. After some years of work aimed at improving the classification system using photomicrographs, it was decided to run a round robin exercise on microscopy samples. The classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites. This paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier. Four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed. Results indicated that the reflectance of particles classified as excellent, good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed. The differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants. Overall, satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed. This was so for samples having abundant and easy to identify vitrinites (higher plant-derived organic matter) as well as for samples with scarce and difficult to identify particles (samples with dominant marine-derived organic matter). The highest discrepancies were found for the organic-rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult. Special instructions should be provided for the analysis of this sort of samples. The certainty of identification of the vitrinite associated with the vitrinite

  3. Soiling of building envelope surfaces and its effect on solar reflectance – Part II: Development of an accelerated aging method for roofing materials

    Energy Technology Data Exchange (ETDEWEB)

    Sleiman, Mohamad [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kirchstetter, Thomas W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Berdahl, Paul [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gilbert, Haley E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Quelen, Sarah [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Marlot, Lea [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Preble, Chelsea V. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Chen, Sharon [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Montalbano, Amandine [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rosseler, Olivier [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Akbari, Hashem [Concordia Univ., Montreal (Canada); Levinson, Ronnen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Destaillats, Hugo [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-01-09

    Highly reflective roofs can decrease the energy required for building air conditioning, help mitigate the urban heat island effect, and slow global warming. However, these benefits are diminished by soiling and weathering processes that reduce the solar reflectance of most roofing materials. Soiling results from the deposition of atmospheric particulate matter and the growth of microorganisms, each of which absorb sunlight. Weathering of materials occurs with exposure to water, sunlight, and high temperatures. This study developed an accelerated aging method that incorporates features of soiling and weathering. The method sprays a calibrated aqueous soiling mixture of dust minerals, black carbon, humic acid, and salts onto preconditioned coupons of roofing materials, then subjects the soiled coupons to cycles of ultraviolet radiation, heat and water in a commercial weatherometer. Three soiling mixtures were optimized to reproduce the site-specific solar spectral reflectance features of roofing products exposed for 3 years in a hot and humid climate (Miami, Florida); a hot and dry climate (Phoenix, Arizona); and a polluted atmosphere in a temperate climate (Cleveland, Ohio). A fourth mixture was designed to reproduce the three-site average values of solar reflectance and thermal emittance attained after 3 years of natural exposure, which the Cool Roof Rating Council (CRRC) uses to rate roofing products sold in the US. This accelerated aging method was applied to 25 products₋single ply membranes, factory and field applied coatings, tiles, modified bitumen cap sheets, and asphalt shingles₋and reproduced in 3 days the CRRC's 3-year aged values of solar reflectance. In conclusion, this accelerated aging method can be used to speed the evaluation and rating of new cool roofing materials.

  4. Joint Retrieval Of Surface Reflectance And Aerosol Properties: Application To MSG/SEVIRI in the framework of the aerosol_cci project

    Science.gov (United States)

    Luffarelli, Marta; Govaerts, Yves; Goossens, Cedric

    2017-04-01

    A new versatile algorithm for the joint retrieval of surface reflectance and aerosol properties has been developed and tested at Rayference. This algorithm, named Combined Inversion of Surface and Aerosols (CISAR), includes a fast physically-based Radiative Transfer Model (RTM) accounting for the surface reflectance anisotropy and its coupling with aerosol scattering. This RTM explicitly solves the radiative transfer equation during the inversion process, without relying on pre-calculated integrals stored in LUT, allowing for a continuous variation of the state variables in the solution space. The inversion is based on a Optimal Estimation (OE) approach, which seeks for the best balance between the information coming from the observation and the a priori information. The a priori information is any additional knowledge on the observed system and it can concern the magnitude of the state variable or constraints on temporal and spectral variability. Both observations and priori information are provided with the corresponding uncertainty. For each processed spectral band, CISAR delivers the surface Bidirectional Reflectance Factor (BRF) and aerosol optical thickness, discriminating the effects of small and large particles. It also provides the associated uncertainty covariance matrix for every processed pixels. In the framework of the ESA aerosol_cci project, CISAR is applied on TOA BRF acquired by SEVIRI onboard Meteosat Second Generation (MSG) in the VIS0.6, VIS0.8 and NIR1.6 spectral bands. SEVIRI observations are accumulated during several days to document the surface anisotropy and minimize the impact of clouds. While surface radiative properties are supposed constant during this accumulation period, aerosol properties are derived on an hourly basis. The information content of each MSG/SEVIRI band will be provided based on the analysis of the posterior uncertainty covariance matrix. The analysis will demonstrate in particular the capability of CISAR to decouple

  5. ATLAS FCal Diagnostics using the Calibration Pulse

    CERN Document Server

    Rutherfoord, J

    2004-01-01

    The calibration pulser in the ATLAS Forward Calorimeter electronics is used to 1) directly calibrate the warm, active electronics and 2) diagnose the cold, passive electronics chain all the way to the liquid argon electrodes. The study presented here shows that reflections of the calibration pulse coming from discontinuities located at or between the warm preamplifier and the electrode can differentiate and identify all known defects so far observed in this chain.

  6. Principal component analysis for surface reflection components and structure in the facial image and synthesis of the facial image in various ages

    Science.gov (United States)

    Hirose, Misa; Toyota, Saori; Ojima, Nobutoshi; Ogawa-Ochiai, Keiko; Tsumura, Norimichi

    2015-03-01

    In this paper, principal component analysis is applied to pigmentation distributions, surface reflectance components and facial landmarks in the whole facial images to obtain feature values. Furthermore, the relationship between the obtained feature vectors and age is estimated by multiple regression analysis to modulate facial images in woman of ages 10 to 70. In our previous work, we analyzed only pigmentation distributions and the reproduced images looked younger than the reproduced age by the subjective evaluation. We considered that this happened because we did not modulate the facial structures and detailed surfaces such as wrinkles. By analyzing landmarks represented facial structures and surface reflectance components, we analyzed the variation of facial structures and fine asperity distributions as well as pigmentation distributions in the whole face. As a result, our method modulate the appearance of a face by changing age more appropriately.

  7. Summary of KOMPSAT-5 Calibration and Validation

    Science.gov (United States)

    Yang, D.; Jeong, H.; Lee, S.; Kim, B.

    2013-12-01

    Korean Multi-Purpose Satellite 5 (KOMPSAT-5), equipped with high resolution X-band (9.66 GHz) Synthetic Aperture Radar (SAR), is planning to be launched on August 22, 2013. With the satellite's primary mission objective being providing Geographical Information System (GIS), Ocean monitoring and Land management, and Disaster and ENvironment monitoring (GOLDEN), it is expected that its applications for scientific research on geographical processes will be extensive. In order to meet its mission objective, the KOMPSAT-5 will provide three different kinds of SAR imaging modes; High Resolution Mode (1 m resolution, 5 km swath), Standard Mode (3 m resolution, 30 km swath), and Wide Swath Mode (20 m resolution, 100 km swath). The KOMPSAT-5 will be operated in a 550 km sun-synchronous, dawn- dusk orbit with a 28-day ground repeat cycle providing valuable image information on Earth surface day-or-night and even in bad weather condition. After successful launch of the satellite, it will go through Launch and Early Operation (LEOP) and In-Orbit Testing (IOT) period about for 6 months to carry out various tests on satellite bus and payload systems. The satellite bus system will be tested during the first 3 weeks after the launch focusing on the Attitude and Orbit Control Subsystem (AOCS) and Integrated GPS Occultation Receiver (IGOR) calibration. With the completion of bus system test, the SAR payload system will be calibrated during initial In-Flight check period (11 weeks) by the joint effort of Thales Alenia Space Italy (TAS-I) and Korea Aerospace Research Institute (KARI). The pointing and relative calibration will be carried out during this period by analyzing the doppler frequency and antenna beam pattern of reflected microwave signal from selected regions with uniform backscattering coefficients (e.g. Amazon rainforest). A dedicated SAR calibration, called primary calibration, will be allocated at the end of LEOP for 12 weeks to perform thorough calibration activities

  8. RADIOMETRIC CALIBRATION OF AIRBORNE LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    Pilarska Magdalena

    2016-12-01

    Full Text Available Airborne laser scanning (ALS is widely used passive remote sensing technique. The radiometric calibration of ALS data is presented in this article. This process is a necessary element in data processing since it eliminates the influence of the external factors on the obtained values of radiometric features such as range and incidence angle. The datasets were captured with three different laser scanners; since each of these operates at a different wavelength (532, 106 4 and 1550 nm this makes the experiment more interesting. Radiometric calibration is a complex process, and a short theoretical background is therefore provided at the beginning of the article. The applied calibration procedure relies on areas with known reflectivity . The calibration region s should exhibit s table radiometric properties, therefore asphalt is used to calibrate each dataset and calculate a calibration constant for each flight block (wavelength independently . Following this, the results of radiometric calibration , reflectance and backscattering coefficient, are presented and discussed in detail. Finally, the obtained reflectance values are compared with spectral characteristics. It could be shown that the reflectance values which result from radiometric calibration are similar to values presented on spectral characteristics.

  9. Protocol for Validation of the Land Surface Reflectance Fundamental Climate Data Record using AERONET: Application to the Global MODIS and VIIRS Data Records

    Science.gov (United States)

    Roger, J. C.; Vermote, E.; Holben, B. N.

    2014-12-01

    The land surface reflectance is a fundamental climate data record at the basis of the derivation of other climate data records (Albedo, LAI/Fpar, Vegetation indices) and a key parameter in the understanding of the land-surface-climate processes. It is essential that a careful validation of its uncertainties is performed on a global and continuous basis. One approach is the direct comparison of this product with ground measurements but that approach presents several issues related to scale, the episodic nature of ground measurements and the global representativeness. An alternative is to compare the surface reflectance product to reference reflectance determined from Top of atmosphere reflectance corrected using accurate radiative transfer code and very detailed measurements of the atmosphere obtained over the AERONET sites (Vermote and al, 2014, RSE) which allows to test for a large range of aerosol characteristics; formers being important inputs for atmospheric corrections. However, the application of this method necessitates the definition of a very detailed protocol for the use of AERONET data especially as far as size distribution and absorption are concerned, so that alternative validation methods or protocols could be compared. This paper describes the protocol we have been working on based on our experience with the AERONET data and its application to the MODIS and VIIRS record.

  10. An Automatic System for Determining Solar Absorptance and Thermal Emittance of Surfaces from Spectral Normal Reflectance Measurements

    National Research Council Canada - National Science Library

    Teichman, Louis

    1965-01-01

    .... The system consists of two spectrophotometers used to make optical reflectance measurements, electronic digitizing equipment to record the data, and a high-speed electronic computer to calculate the desired results...

  11. Investigation of cavity mode and excitonic transition in an InGaAs/GaAs/AlGaAs vertical-cavity surface emitting laser structure by variable-temperature micro-photoluminescence, reflectance and photomodulated reflectance

    International Nuclear Information System (INIS)

    Yu, J L; Chen, Y H; Jiang, C Y; Zhang, H Y

    2012-01-01

    Variable-temperature micro-photoluminescence (μ-PL), reflectance (R) and photomodulated reflectance (PR) have been used to study an InGaAs/GaAs/AlGaAs vertical-cavity surface emitting laser (VCSEL) structure. μ-PL and R spectra have been recorded at different temperatures between 80 K and 300 K By comparing μ-PL with R spectra, both the excitonic transition and cavity mode are clearly identified. The Variable-temperature μ-PL and PR results of the etched sample with the top distributed Bragg reflectors (DBR) being removed further confirmed our identification. Our results demonstrate that variable-temperature μ-PL is a powerful noninvasive tool to measure accurate the quantum well transition and the cavity mode alignment.

  12. Tools for measuring surface cleanliness

    Energy Technology Data Exchange (ETDEWEB)

    Schroder, Mark Stewart (Hendersonville, NC); Woodmansee, Donald Ernest (Simpsonville, SC); Beadie, Douglas Frank (Greenville, SC)

    2002-01-01

    A procedure and tools for quantifying surface cleanliness are described. Cleanliness of a target surface is quantified by wiping a prescribed area of the surface with a flexible, bright white cloth swatch, preferably mounted on a special tool. The cloth picks up a substantial amount of any particulate surface contamination. The amount of contamination is determined by measuring the reflectivity loss of the cloth before and after wiping on the contaminated system and comparing that loss to a previous calibration with similar contamination. In the alternative, a visual comparison of the contaminated cloth to a contamination key provides an indication of the surface cleanliness.

  13. Effects of roughness and temperature on low-energy hydrogen positive and negative ion reflection from silicon and carbon surfaces.

    Science.gov (United States)

    Tanaka, N; Kato, S; Miyamoto, T; Nishiura, M; Tsumori, K; Matsumoto, Y; Kenmotsu, T; Okamoto, A; Kitajima, S; Sasao, M; Wada, M; Yamaoka, H

    2014-02-01

    Angle-resolved energy distribution functions of positive and negative hydrogen ions produced from a rough-finished Si surface under 1 keV proton irradiation have been measured. The corresponding distribution from a crystalline surface and a carbon surface are also measured for comparison. Intensities of positive and negative ions from the rough-finished Si are substantially smaller than those from crystalline Si. The angular distributions of these species are broader for rough surface than the crystalline surface. No significant temperature dependence for positive and negative ion intensities is observed for all samples in the temperature range from 300 to 400 K.

  14. Radiometric calibration stability and inter-calibration of solar-band instruments in orbit using the moon

    Science.gov (United States)

    Stone, T.C.

    2008-01-01

    With the increased emphasis on monitoring the Earth's climate from space, more stringent calibration requirements are being placed on the data products from remote sensing satellite instruments. Among these are stability over decade-length time scales and consistency across sensors and platforms. For radiometer instruments in the solar reflectance wavelength range (visible to shortwave infrared), maintaining calibration on orbit is difficult due to the lack of absolute radiometric standards suitable for flight use. The Moon presents a luminous source that can be viewed by all instruments in Earth orbit. Considered as a solar diffuser, the lunar surface is exceedingly stable. The chief difficulty with using the Moon is the strong variations in the Moon's brightness with illumination and viewing geometry. This mandates the use of a photometric model to compare lunar observations, either over time by the same instrument or between instruments. The U.S. Geological Survey in Flagstaff, Arizona, under NASA sponsorship, has developed a model for the lunar spectral irradiance that explicitly accounts for the effects of phase, the lunar librations, and the lunar surface reflectance properties. The model predicts variations in the Moon's brightness with precision ???1% over a continuous phase range from eclipse to the quarter lunar phases. Given a time series of Moon observations taken by an instrument, the geometric prediction capability of the lunar irradiance model enables sensor calibration stability with sub-percent per year precision. Cross-calibration of instruments with similar passbands can be achieved with precision comparable to the model precision. Although the Moon observations used for intercomparison can be widely separated in phase angle and/or time, SeaWiFS and MODIS have acquired lunar views closely spaced in time. These data provide an example to assess inter-calibration biases between these two instruments.

  15. Consistency of land surface reflectance data: presentation of a new tool and case study with Formosat-2, SPOT-4 and Landsat-5/7/8 data

    Science.gov (United States)

    Claverie, M.; Vermote, E.; Franch, B.; Huc, M.; Hagolle, O.; Masek, J.

    2013-12-01

    Maintaining consistent dataset of Surface Reflectance (SR) data derived from the large panel of in-orbit sensors is an important challenge to ensure long term analysis of earth observation data. Continuous validation of such SR products through comparison with a reference dataset is thus an important challenge. Validating with in situ or airborne SR data is not easy since the sensors rarely match completely the same spectral, spatial and directional characteristics of the satellite measurement. Inter-comparison between satellites sensors data appears as a valuable tool to maintain a long term consistency of the data. However, satellite data are acquired at various times of the day (i.e., variation of the atmosphere content) and within a relative large range of geometry (view and sun angles). Also, even if band-to-band spectral characteristics of optical sensors are closed, they rarely have identical spectral responses. As the results, direct comparisons without consideration of these differences are poorly suitable. In this study, we suggest a new systematic method to assess land optical SR data from high to medium resolution sensors. We used MODIS SR products (MO/YD09CMG) which benefit from a long term calibration/validation process, to assess SR from 3 sensors data: Formosat-2 (280 scenes 24x24km - 5 sites), SPOT-4 (62 scenes 120x60km - 1 site) and Landsat-5/7 (104 180x180km scenes - 50 sites). The main issue concerns the difference in term of geometry acquisition between MODIS and compared sensors data. We used the VJB model (Vermote et al. 2009, TGRS) to correct MODIS SR from BRDF effects and to simulate SR at the corresponding geometry (view and sun angles) of each pixel of the compared sensor data. The comparison is done at the CMG spatial resolution (0.05°) which ensures a constant field-of-view and negligible geometrical errors. Figure 1 displays the summary of the NIR results through APU graphs where metrics A, P and U stands for Accuracy, Precision and

  16. Results from source-based and detector-based calibrations of a CLARREO calibration demonstration system

    Science.gov (United States)

    Angal, Amit; McCorkel, Joel; Thome, Kurt

    2016-09-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission is formulated to determine long-term climate trends using SI-traceable measurements. The CLARREO mission will include instruments operating in the reflected solar (RS) wavelength region from 320 nm to 2300 nm. The Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO and facilitates testing and evaluation of calibration approaches. The basis of CLARREO and SOLARIS calibration is the Goddard Laser for Absolute Measurement of Response (GLAMR) that provides a radiance-based calibration at reflective solar wavelengths using continuously tunable lasers. SI-traceability is achieved via detector-based standards that, in GLAMR's case, are a set of NIST-calibrated transfer radiometers. A portable version of the SOLARIS, Suitcase SOLARIS is used to evaluate GLAMR's calibration accuracies. The calibration of Suitcase SOLARIS using GLAMR agrees with that obtained from source-based results of the Remote Sensing Group (RSG) at the University of Arizona to better than 5% (k=2) in the 720-860 nm spectral range. The differences are within the uncertainties of the NIST-calibrated FEL lamp-based approach of RSG and give confidence that GLAMR is operating at Suitcase SOLARIS instrument also discussed and the next edition of the SOLARIS instrument (Suitcase SOLARIS- 2) is expected to provide an improved mechanism to further assess GLAMR and CLARREO calibration approaches.

  17. Investigation on bragg reflection of surface water waves induced by a train of fixed floating pontoon breakwaters

    Directory of Open Access Journals (Sweden)

    Huei-Tau Ouyang

    2015-11-01

    Full Text Available The water wave characteristics of Bragg reflections from a train of fixed floating pontoon breakwaters was studied numerically. A numerical model of boundary discretization type was developed to calculate the wave field. The model was verified by comparing to analytical data in literature and good agreements were achieved. Series of parametric studies were conducted systematically to investigate the dependence of the reflected coefficients by the Bragg scattering on the design variables, including the spacing between the breakwaters, the total number of installed breakwaters, the draft and width do the breakwater, and wave length. Certain wave characteristics of the Bragg reflections were observed and discussed in details which might be of help for practical engineering applications in shoreline protection from incident waves.

  18. Final report for the project "Improving the understanding of surface-atmosphere radiative interactions by mapping surface reflectance over the ARM CART site" (award DE-FG02-02ER63351)

    Energy Technology Data Exchange (ETDEWEB)

    Alexander P. Trishchenko; Yi Luo; Konstantin V. Khlopenkov, William M. Park; Zhanqing Li; Maureen Cribb

    2008-11-28

    Surface spectral reflectance (albedo) is a fundamental variable affecting the transfer of solar radiation and the Earth’s climate. It determines the proportion of solar energy absorbed by the surface and reflected back to the atmosphere. The International Panel on Climate Change (IPCC) identified surface albedo among key factors influencing climate radiative forcing. Accurate knowledge of surface reflective properties is important for advancing weather forecasting and climate change impact studies. It is also important for determining radiative impact and acceptable levels of greenhouse gases in the atmosphere, which makes this work strongly linked to major scientific objectives of the Climate Change Research Division (CCRD) and Atmospheric Radiation Measurement (ARM) Program. Most significant accomplishments of eth project are listed below. I) Surface albedo/BRDF datasets from 1995 to the end of 2004 have been produced. They were made available to the ARM community and other interested users through the CCRS public ftp site ftp://ftp.ccrs.nrcan.gc.ca/ad/CCRS_ARM/ and ARM IOP data archive under “PI data Trishchenko”. II) Surface albedo properties over the ARM SGP area have been described for 10-year period. Comparison with ECMWF data product showed some deficiencies in the ECMWF surface scheme, such as missing some seasonal variability and no dependence on sky-conditions which biases surface energy budget and has some influence of the diurnal cycle of upward radiation and atmospheric absorption. III) Four surface albedo Intensive Observation Period (IOP) Field Campaigns have been conducted for every season (August, 2002, May 2003, February 2004 and October 2004). Data have been prepared, documented and transferred to ARM IOP archive. Nine peer-reviewed journal papers and 26 conference papers have been published.

  19. Glazed ceramic roof tiles: influence of surface features in the solar reflectance index; Influencia das caracteristicas da superficie no indice de refletancia solar de telhas ceramicas esmaltadas

    Energy Technology Data Exchange (ETDEWEB)

    Bortoli, Leitcia Silva de; Stapait, Camila Cristina; Marinoski, Deivis Luis; Fredel, Marcio Celso; Schabbach, Luciana M., E-mail: luciana.maccarini@ufsc.br [Universidade Federal de Santa Catarina (UFSC), Blumenau, SC (Brazil)

    2016-07-01

    In this study the influence of surface features of ceramic roof tiles in the solar reflectance index were evaluated. Two glazed ceramic roof tiles (type stoneware) with the same color (ivory) but with different appearance (matte and brilliant) were the focus of the analysis. The Solar Reflectance Index (SRI) of the roofs tiles were determined by the solar reflectance values (UV-VIS-NIR) and emittance, measured in laboratory. The samples showed SRI> 39 in accordance with LEED certification criteria (Leadership in Energy and Environmental Design), contributing to minimizing the Heat Island Effects. Although the matte roof tile shows a slightly higher SRI value (82) than the brilliant one (78), the results for the variables that composes the SRI value (reflectance and emittance) were very similar. Analysis of XRD, SEM and EDS performed on the surfaces of the two roofs indicated for the matte glaze the presence of microcrystals (with barium and zinc) that can contribute to the slightly highest value of SRI. The roughness (optical interferometer white light) and the brightness (brightness meter) of the samples were also measured. (author)

  20. Cross-Calibration of GF-1/WFV over a Desert Site Using Landsat-8/OLI Imagery and ZY-3/TLC Data

    Directory of Open Access Journals (Sweden)

    Aixia Yang

    2015-08-01

    Full Text Available The wide field of view (WFV is an optical imaging sensor on-board the Gao Fen 1 (GF-1. The WFV lacks an on-board calibrator, so on-orbit radiometric calibration is required. Zhong et al. proposed a method for cross-calibrating the charge-coupled device on-board the Chinese Huan Jing 1 (HJ-1/CCD that can be applied to the GF-1/WFV. However, the accuracy is limited because of the wider radiometric dynamic range and the higher spatial resolution of the GF-1/WFV. Therefore, Landsat-8 Operational Land Imager (OLI imagery with a radiometric resolution similar to that of the GF-1/WFV and DEM extracted from ZY-3 three-line array panchromatic camera (TLC with a higher spatial resolution were used. A calibration site with uniform surface material and a natural topographic variation was selected, and a model of this site’s bidirectional reflectance distribution function (BRDF was developed. The model has excellent agreement with the real situation, as shown by the comparison of the simulations to the actual OLI surface reflectance. Then, the model was used to calibrate the WFV. Compared with the TOA reflectance from synchronized Landsat-8/OLI images, all errors calculated with the calibration coefficients retrieved in this paper are less than 5%, much less than the errors calculated with the calibration coefficients given by the China Centre for Resource Satellite Data and Application (CRESDA.

  1. Traceable Pyrgeometer Calibrations

    Energy Technology Data Exchange (ETDEWEB)

    Dooraghi, Mike; Kutchenreiter, Mark; Reda, Ibrahim; Habte, Aron; Sengupta, Manajit; Andreas, Afshin; Newman, Martina

    2016-05-02

    This poster presents the development, implementation, and operation of the Broadband Outdoor Radiometer Calibrations (BORCAL) Longwave (LW) system at the Southern Great Plains Radiometric Calibration Facility for the calibration of pyrgeometers that provide traceability to the World Infrared Standard Group.

  2. Improving the SMAC atmospheric correction code by analysis of Meteosat Second Generation NDVI and surface reflectance data

    DEFF Research Database (Denmark)

    Proud, Simon Richard; Rasmussen, M.O.; Fensholt, R.

    2010-01-01

    . When examining the Normalised Difference Vegetation Index (NDVI), the relative difference between SMAC and in-situ values decreases by 1.5% with the improvements in place. Similarly, the mean relative difference between SMAC and 6S reflectance values decreases by a mean of 13, 14.5 and 8...

  3. TWSTFT Link Calibration Report

    Science.gov (United States)

    2015-09-01

    traveling calibration station (calibrator) consisting of N (≥2) GNSS receivers+antennas+cables and PPS/frequency-distributors. It is a pre-cabled black...the PTB is taken as the reference of the calibration, a GNSS time link correction is equal to the classic GNSS equipment calibration correction [8...TWSTFT link calibration. If we replace the TWSTFT link by a GNSS link or a optical fiber (OF), it becomes a GNSS or an OF time link calibration. This

  4. Primary calibration of TXRF in comparison with the standard droplet procedure

    International Nuclear Information System (INIS)

    Dobler, M.; Reus, U.; Knoth, J.; Schwenke, H.

    2000-01-01

    For the determination of contamination on wafer surfaces with total reflection x-ray fluorescence spectrometry (TXRF) normally external 1 ng Ni droplet standards were used for calibration. This method is based on several assumptions about the properties of the standard droplet which are strongly affected by the preparation of the samples. In this paper a study is resented which compares the external droplet method with a calibration procedure using the fundamental physical background of total reflection x-ray fluorescence spectrometry and the properties of Ni bulk material. The particular features of the two methods will be discussed and the obtained results compared to each other. It is demonstrated in this study that the calibration with Ni bulk material is a primary method which offers several advantages compared to the calibration based on droplet standards. These advantages are unique and enable a more reliable and reproducible quantification of contamination on wafer surfaces. This is caused by the fact that the method is standardless and only based on fundamental parameters and natural constants. It is also demonstrated that effects which could be caused by especial features of the measured samples (particle or film, e.g.) or by the degradation of the calibration sample could be excluded. (author)