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Sample records for absolute calibration accuracy

  1. An absolute calibration system for millimeter-accuracy APOLLO measurements

    Science.gov (United States)

    Adelberger, E. G.; Battat, J. B. R.; Birkmeier, K. J.; Colmenares, N. R.; Davis, R.; Hoyle, C. D.; Huang, L. R.; McMillan, R. J.; Murphy, T. W., Jr.; Schlerman, E.; Skrobol, C.; Stubbs, C. W.; Zach, A.

    2017-12-01

    Lunar laser ranging provides a number of leading experimental tests of gravitation—important in our quest to unify general relativity and the standard model of physics. The apache point observatory lunar laser-ranging operation (APOLLO) has for years achieved median range precision at the  ∼2 mm level. Yet residuals in model-measurement comparisons are an order-of-magnitude larger, raising the question of whether the ranging data are not nearly as accurate as they are precise, or if the models are incomplete or ill-conditioned. This paper describes a new absolute calibration system (ACS) intended both as a tool for exposing and eliminating sources of systematic error, and also as a means to directly calibrate ranging data in situ. The system consists of a high-repetition-rate (80 MHz) laser emitting short (work on model capabilities. The ACS provides the means to deliver APOLLO data both accurate and precise below the 2 mm level.

  2. Improvement of Gaofen-3 Absolute Positioning Accuracy Based on Cross-Calibration

    Directory of Open Access Journals (Sweden)

    Mingjun Deng

    2017-12-01

    Full Text Available The Chinese Gaofen-3 (GF-3 mission was launched in August 2016, equipped with a full polarimetric synthetic aperture radar (SAR sensor in the C-band, with a resolution of up to 1 m. The absolute positioning accuracy of GF-3 is of great importance, and in-orbit geometric calibration is a key technology for improving absolute positioning accuracy. Conventional geometric calibration is used to accurately calibrate the geometric calibration parameters of the image (internal delay and azimuth shifts using high-precision ground control data, which are highly dependent on the control data of the calibration field, but it remains costly and labor-intensive to monitor changes in GF-3’s geometric calibration parameters. Based on the positioning consistency constraint of the conjugate points, this study presents a geometric cross-calibration method for the rapid and accurate calibration of GF-3. The proposed method can accurately calibrate geometric calibration parameters without using corner reflectors and high-precision digital elevation models, thus improving absolute positioning accuracy of the GF-3 image. GF-3 images from multiple regions were collected to verify the absolute positioning accuracy after cross-calibration. The results show that this method can achieve a calibration accuracy as high as that achieved by the conventional field calibration method.

  3. Calibration with Absolute Shrinkage

    DEFF Research Database (Denmark)

    Øjelund, Henrik; Madsen, Henrik; Thyregod, Poul

    2001-01-01

    In this paper, penalized regression using the L-1 norm on the estimated parameters is proposed for chemometric je calibration. The algorithm is of the lasso type, introduced by Tibshirani in 1996 as a linear regression method with bound on the absolute length of the parameters, but a modification...

  4. Calibration with Absolute Shrinkage

    DEFF Research Database (Denmark)

    Øjelund, Henrik; Madsen, Henrik; Thyregod, Poul

    2001-01-01

    In this paper, penalized regression using the L-1 norm on the estimated parameters is proposed for chemometric je calibration. The algorithm is of the lasso type, introduced by Tibshirani in 1996 as a linear regression method with bound on the absolute length of the parameters, but a modification...... to the lasso. The lasso is applied both directly as a calibration method and as a method to select important variables/wave lengths. It is demonstrated that the lasso algorithm, in general, leads to parameter estimates of which some are zero while others are quite large (compared to e.g. the traditional PLS...

  5. High accuracy absolute distance metrology

    Science.gov (United States)

    Swinkels, Bas L.; Bhattacharya, Nandini; Verlaan, Ad L.; Braat, Joseph J. M.

    2017-11-01

    One of ESA's future missions is the Darwin Space Interferometer, which aims to detect planets around nearby stars using optical aperture synthesis with free-flying telescopes. Since this involves interfering white (infra-red) light over large distances, the mission is not possible without a complex metrology system that monitors various speeds, distances and angles between the satellites. One of its sub-systems should measure absolute distances with an accuracy of around 70 micrometer over distances up to 250 meter. To enable such measurements, we are investigating a technique called frequency sweeping interferometry, in which a single laser is swept over a large known frequency range. Central to our approach is the use of a very stable, high finesse Fabry-Ṕerot cavity, to which the laser is stabilized at the endpoints of the frequency sweep. We will discuss the optical set-up, the control system that controls the fast sweeping, the calibration and the data analysis. We tested the system using long fibers and achieved a repeatability of 50 micrometers at a distance of 55 meters. We conclude with some recommendations for further improvements and the adaption for use in space.

  6. Achieving Climate Change Absolute Accuracy in Orbit

    Science.gov (United States)

    Wielicki, Bruce A.; Young, D. F.; Mlynczak, M. G.; Thome, K. J; Leroy, S.; Corliss, J.; Anderson, J. G.; Ao, C. O.; Bantges, R.; Best, F.; hide

    2013-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5-50 micron), the spectrum of solar radiation reflected by the Earth and its atmosphere (320-2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a "NIST [National Institute of Standards and Technology] in orbit." CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations.

  7. Absolute calibration in vivo measurement systems

    International Nuclear Information System (INIS)

    Kruchten, D.A.; Hickman, D.P.

    1991-02-01

    Lawrence Livermore National Laboratory (LLNL) is currently investigating a new method for obtaining absolute calibration factors for radiation measurement systems used to measure internally deposited radionuclides in vivo. Absolute calibration of in vivo measurement systems will eliminate the need to generate a series of human surrogate structures (i.e., phantoms) for calibrating in vivo measurement systems. The absolute calibration of in vivo measurement systems utilizes magnetic resonance imaging (MRI) to define physiological structure, size, and composition. The MRI image provides a digitized representation of the physiological structure, which allows for any mathematical distribution of radionuclides within the body. Using Monte Carlo transport codes, the emission spectrum from the body is predicted. The in vivo measurement equipment is calibrated using the Monte Carlo code and adjusting for the intrinsic properties of the detection system. The calibration factors are verified using measurements of existing phantoms and previously obtained measurements of human volunteers. 8 refs

  8. PLEIADES ABSOLUTE CALIBRATION : INFLIGHT CALIBRATION SITES AND METHODOLOGY

    Directory of Open Access Journals (Sweden)

    S. Lachérade

    2012-07-01

    Full Text Available In-flight calibration of space sensors once in orbit is a decisive step to be able to fulfil the mission objectives. This article presents the methods of the in-flight absolute calibration processed during the commissioning phase. Four In-flight calibration methods are used: absolute calibration, cross-calibration with reference sensors such as PARASOL or MERIS, multi-temporal monitoring and inter-bands calibration. These algorithms are based on acquisitions over natural targets such as African deserts, Antarctic sites, La Crau (Automatic calibration station and Oceans (Calibration over molecular scattering or also new extra-terrestrial sites such as the Moon and selected stars. After an overview of the instrument and a description of the calibration sites, it is pointed out how each method is able to address one or several aspects of the calibration. We focus on how these methods complete each other in their operational use, and how they help building a coherent set of information that addresses all aspects of in-orbit calibration. Finally, we present the perspectives that the high level of agility of PLEIADES offers for the improvement of its calibration and a better characterization of the calibration sites.

  9. NIST Stars: Absolute Spectrophotometric Calibration of Vega and Sirius

    Science.gov (United States)

    Deustua, Susana; Woodward, John T.; Rice, Joseph P.; Brown, Steven W.; Maxwell, Stephen E.; Alberding, Brian G.; Lykke, Keith R.

    2018-01-01

    Absolute flux calibration of standard stars, traceable to SI (International System of Units) standards, is essential for 21st century astrophysics. Dark energy investigations that rely on observations of Type Ia supernovae and precise photometric redshifts of weakly lensed galaxies require a minimum accuracy of 0.5 % in the absolute color calibration. Studies that aim to address fundamental stellar astrophysics also benefit. In the era of large telescopes and all sky surveys well-calibrated standard stars that do not saturate and that are available over the whole sky are needed. Significant effort has been expended to obtain absolute measurements of the fundamental standards Vega and Sirius (and other stars) in the visible and near infrared, achieving total uncertainties between1% and 3%, depending on wavelength, that do not meet the needed accuracy. The NIST Stars program aims to determine the top-of-the-atmosphere absolute spectral irradiance of bright stars to an uncertainty less than 1% from a ground-based observatory. NIST Stars has developed a novel, fully SI-traceable laboratory calibration strategy that will enable achieving the desired accuracy. This strategy has two key components. The first is the SI-traceable calibration of the entire instrument system, and the second is the repeated spectroscopic measurement of the target star throughout the night. We will describe our experimental strategy, present preliminary results for Vega and Sirius and an end-to-end uncertainty budget

  10. Absolute Mass Scale Calibration Using Z->mumu

    CERN Document Server

    Aleksa, Martin

    1999-01-01

    Detailed simulations have been performed, investigating the possibility of calibrating the absolute mass scale of the muon spectrometer by using Z->mumu A sample of 10000 events was processed through DICE/ATRECON applying different scale factors to the magnetic field as a function of phi and eta. It is shown that these scale factors could be retrieved with high accuracy together with the muon energy loss as a function of eta. It is shown that the energy loss in the barrel region could be found with an accuracy of 45 MeV while calibrating at the same time 2 magnetic field scale factors with an accuracy of 0.001.

  11. How calibration and reference spectra affect the accuracy of absolute soft X-ray solar irradiance measured by the SDO/EVE/ESP during high solar activity

    Science.gov (United States)

    Didkovsky, Leonid; Wieman, Seth; Woods, Thomas

    2016-10-01

    The Extreme ultraviolet Spectrophotometer (ESP), one of the channels of SDO's Extreme ultraviolet Variability Experiment (EVE), measures solar irradiance in several EUV and soft x-ray (SXR) bands isolated using thin-film filters and a transmission diffraction grating, and includes a quad-diode detector positioned at the grating zeroth-order to observe in a wavelength band from about 0.1 to 7.0 nm. The quad diode signal also includes some contribution from shorter wavelength in the grating's first-order and the ratio of zeroth-order to first-order signal depends on both source geometry, and spectral distribution. For example, radiometric calibration of the ESP zeroth-order at the NIST SURF BL-2 with a near-parallel beam provides a different zeroth-to-first-order ratio than modeled for solar observations. The relative influence of "uncalibrated" first-order irradiance during solar observations is a function of the solar spectral irradiance and the locations of large Active Regions or solar flares. We discuss how the "uncalibrated" first-order "solar" component and the use of variable solar reference spectra affect determination of absolute SXR irradiance which currently may be significantly overestimated during high solar activity.

  12. Absolute scale-based imaging position encoder with submicron accuracy

    Science.gov (United States)

    Anisimov, Andrey G.; Pantyushin, Anton V.; Lashmanov, Oleg U.; Vasilev, A. S.; Timofeev, Alexander N.; Korotaev, Valery V.; Gordeev, Sergey V.

    2013-04-01

    Study is devoted to experimental research and development of absolute imaging position encoder based on standard calibrated scale of invar alloy with 1 mm spacing. The encoder uses designed imaging system as a vernier and absolute magnetic encoder as a rough indication. The features of optical design, choice and use of imaging system as long as indexes images processing algorithm are described. A shadow method was implemented: indexes images on a CCD array are formed by the lens focused at the scale surface; the laser module lights up the scale through a beam-splitting prism by a parallel beam. Further dark indexes images on a light scale background are detected and analyzed to estimate the encoder position. Full range of experimental tests was set to calibrate the encoder and to estimate the accuracy. As a result, accuracy close to 1 μm at 1 m was achieved.

  13. 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.

  14. Absolute calibration of Doppler coherence imaging velocity images

    Science.gov (United States)

    Samuell, C. M.; Allen, S. L.; Meyer, W. H.; Howard, J.

    2017-08-01

    A new technique has been developed for absolutely calibrating a Doppler Coherence Imaging Spectroscopy interferometer for measuring plasma ion and neutral velocities. An optical model of the interferometer is used to generate zero-velocity reference images for the plasma spectral line of interest from a calibration source some spectral distance away. Validation of this technique using a tunable diode laser demonstrated an accuracy better than 0.2 km/s over an extrapolation range of 3.5 nm; a two order of magnitude improvement over linear approaches. While a well-characterized and very stable interferometer is required, this technique opens up the possibility of calibrated velocity measurements in difficult viewing geometries and for complex spectral line-shapes.

  15. Absolute intensity calibration for ECE measurements on EAST

    International Nuclear Information System (INIS)

    Liu Yong; Liu Xiang; Zhao Hailin

    2014-01-01

    In this proceeding, the results of the in-situ absolute intensity calibration for ECE measurements on EAST are presented. A 32-channel heterodyne radiometer system and a Michelson interferometer on EAST have been calibrated independently, and preliminary results from plasma operation indicate a good agreement between the electron temperature profiles obtained with different systems. (author)

  16. Absolute gravimetry on the agulhas negras calibration line

    OpenAIRE

    Sousa, Mauro Andrade de; Santos, Alcides Antonio dos

    2010-01-01

    The Agulhas Negras Gravity Calibration Line was established in the mid 1980s using LaCoste & Romberg gravimeters model "G" only. Five gravity stations were irregularly positioned along its 200 km length, spanning a total range of 627 mGal. The new absolute gravimeter Micro-g Solutions A-10 #011 of Observatório Nacional was taken to each calibration station and new measurements were made. The local vertical gravity gradient was also measured at each calibration station. This report shows their...

  17. Improving calibration accuracy in gel dosimetry

    International Nuclear Information System (INIS)

    Oldham, M.; McJury, M.; Webb, S.; Baustert, I.B.; Leach, M.O.

    1998-01-01

    A new method of calibrating gel dosimeters (applicable to both Fricke and polyacrylamide gels) is presented which has intrinsically higher accuracy than current methods, and requires less gel. Two test-tubes of gel (inner diameter 2.5 cm, length 20 cm) are irradiated separately with a 10x10cm 2 field end-on in a water bath, such that the characteristic depth-dose curve is recorded in the gel. The calibration is then determined by fitting the depth-dose measured in water, against the measured change in relaxivity with depth in the gel. Increased accuracy is achieved in this simple depth-dose geometry by averaging the relaxivity at each depth. A large number of calibration data points, each with relatively high accuracy, are obtained. Calibration data over the full range of dose (1.6-10 Gy) is obtained by irradiating one test-tube to 10 Gy at dose maximum (D max ), and the other to 4.5 Gy at D max . The new calibration method is compared with a 'standard method' where five identical test-tubes of gel were irradiated to different known doses between 2 and 10 Gy. The percentage uncertainties in the slope and intercept of the calibration fit are found to be lower with the new method by a factor of about 4 and 10 respectively, when compared with the standard method and with published values. The gel was found to respond linearly within the error bars up to doses of 7 Gy, with a slope of 0.233±0.001 s -1 Gy -1 and an intercept of 1.106±0.005 Gy. For higher doses, nonlinear behaviour was observed. (author)

  18. Ensuring long-term stability of infrared camera absolute calibration.

    Science.gov (United States)

    Kattnig, Alain; Thetas, Sophie; Primot, Jérôme

    2015-07-13

    Absolute calibration of cryogenic 3-5 µm and 8-10 µm infrared cameras is notoriously instable and thus has to be repeated before actual measurements. Moreover, the signal to noise ratio of the imagery is lowered, decreasing its quality. These performances degradations strongly lessen the suitability of Infrared Imaging. These defaults are often blamed on detectors reaching a different "response state" after each return to cryogenic conditions, while accounting for the detrimental effects of imperfect stray light management. We show here that detectors are not to be blamed and that the culprit can also dwell in proximity electronics. We identify an unexpected source of instability in the initial voltage of the integrating capacity of detectors. Then we show that this parameter can be easily measured and taken into account. This way we demonstrate that a one month old calibration of a 3-5 µm camera has retained its validity.

  19. 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.

  20. High Accuracy Transistor Compact Model Calibrations

    Energy Technology Data Exchange (ETDEWEB)

    Hembree, Charles E. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Mar, Alan [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Robertson, Perry J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Typically, transistors are modeled by the application of calibrated nominal and range models. These models consists of differing parameter values that describe the location and the upper and lower limits of a distribution of some transistor characteristic such as current capacity. Correspond- ingly, when using this approach, high degrees of accuracy of the transistor models are not expected since the set of models is a surrogate for a statistical description of the devices. The use of these types of models describes expected performances considering the extremes of process or transistor deviations. In contrast, circuits that have very stringent accuracy requirements require modeling techniques with higher accuracy. Since these accurate models have low error in transistor descriptions, these models can be used to describe part to part variations as well as an accurate description of a single circuit instance. Thus, models that meet these stipulations also enable the calculation of quantifi- cation of margins with respect to a functional threshold and uncertainties in these margins. Given this need, new model high accuracy calibration techniques for bipolar junction transis- tors have been developed and are described in this report.

  1. Improved strategies and optimization of calibration models for real-time PCR absolute quantification.

    Science.gov (United States)

    Sivaganesan, Mano; Haugland, Richard A; Chern, Eunice C; Shanks, Orin C

    2010-09-01

    Real-time PCR absolute quantification applications are becoming more common in the recreational and drinking water quality industries. Many methods rely on the use of standard curves to make estimates of DNA target concentrations in unknown samples. Traditional absolute quantification approaches dictate that a standard curve must accompany each experimental run. However, the generation of a standard curve for each qPCR experiment set-up can be expensive and time consuming, especially for studies with large numbers of unknown samples. As a result, many researchers have adopted a master calibration strategy where a single curve is derived from DNA standard measurements generated from multiple instrument runs. However, a master curve can inflate uncertainty associated with intercept and slope parameters and decrease the accuracy of unknown sample DNA target concentration estimates. Here we report two alternative strategies termed 'pooled' and 'mixed' for the generation of calibration equations from absolute standard curves which can help reduce the cost and time of laboratory testing, as well as the uncertainty in calibration model parameter estimates. In this study, four different strategies for generating calibration models were compared based on a series of repeated experiments for two different qPCR assays using a Monte Carlo Markov Chain method. The hierarchical Bayesian approach allowed for the comparison of uncertainty in intercept and slope model parameters and the optimization of experiment design. Data suggests that the 'pooled' model can reduce uncertainty in both slope and intercept parameter estimates compared to the traditional single curve approach. In addition, the 'mixed' model achieved uncertainty estimates similar to the 'single' model while increasing the number of available reaction wells per instrument run. Published by Elsevier Ltd.

  2. Absolute Current Calibrations of 1$\\mu$A CW Electron Beam

    CERN Document Server

    Freyberger, A; Day, A R; Degtiarenko, P; Saha, A; Slachtouski, S

    2005-01-01

    The future experimental program at Jefferson Lab requires an absolute current calibration of a 1$\\mu\\A CW electron beam to better than 1% accuracy. This paper presents the mechanical and electrical design of a Tungsten calorimeter that is being constructed to provide an accurate measurement of the deposited energy. The energy is determined by measuring the change in temperature after beam exposure. Knowledge of the beam energy then yields number of electrons stopped by the calorimeter during the exposure. Simulations show that the energy losses due to electromagnetic and hadronic losses are the dominant uncertainty. Details of the precision thermometry and calibration, mechanical design, thermal simulations and GEANT simulations will be presented.

  3. A Multilaboratory Comparison of Calibration Accuracy and the Performance of External References in Analytical Ultracentrifugation

    OpenAIRE

    Zhao, Huaying;Ghirlando, Rodolfo;Alfonso, Carlos;Arisaka, Fumio;Attali, Ilan;Bain, David L.;Bakhtina, Marina M.;Becker, Donald F.;Bedwell, Gregory J.;Bekdemir, Ahmet;Besong, Tabot M. D.;Birck, Catherine;Brautigam, Chad A.;Brennerman, William;Byron, Olwyn;Bzowska, Agnieszka;Chaires, Jonathan B.;Chaton, Catherine T.;Cölfen, Helmut;Connaghan, Keith D.;Crowley, Kimberly A.;Curth, Ute;Daviter, Tina;Dean, William L.;Díez, Ana I.;Ebel, Christine;Eckert, Debra M.;Eisele, Leslie E.;Eisenstein, Edward;England, Patrick;Escalante, Carlos;Fagan, Jeffrey A.;Fairman, Robert;Finn, Ron M.;Fischle, Wolfgang;de la Torre, José García;Gor, Jayesh;Gustafsson, Henning;Hall, Damien;Harding, Stephen E.;Cifre, José G. Hernández;Herr, Andrew B.;Howell, Elizabeth E.;Isaac, Richard S.;Jao, Shu-Chuan;Jose, Davis;Kim, Soon-Jong;Kokona, Bashkim;Kornblatt, Jack A.;Kosek, Dalibor;Krayukhina, Elena;Krzizike, Daniel;Kusznir, Eric A.;Kwon, Hyewon;Larson, Adam;Laue, Thomas M.;Le Roy, Aline;Leech, Andrew P.;Lilie, Hauke;Luger, Karolin;Luque-Ortega, Juan R.;Ma, Jia;May, Carrie A.;Maynard, Ernest L.;Modrak-Wojcik, Anna;Mok, Yee-Foong;Mücke, Norbert;Nagel-Steger, Luitgard;Narlikar, Geeta J.;Noda, Masanori;Nourse, Amanda;Obsil, Tomas;Park, Chad K.;Park, Jin-Ku;Pawelek, Peter D.;Perdue, Erby E.;Perkins, Stephen J.;Perugini, Matthew A.;Peterson, Craig L.;Peverelli, Martin G.;Piszczek, Grzegorz;Prag, Gali;Prevelige, Peter E.;Raynal, Bertrand D. E.;Rezabkova, Lenka;Richter, Klaus;Ringel, Alison E.;Rosenberg, Rose;Rowe, Arthur J.;Rufer, Arne C.;Scott, David J.;Seravalli, Javier G.;Solovyova, Alexandra S.;Song, Renjie;Staunton, David;Stoddard, Caitlin;Stott, Katherine;Strauss, Holger M.;Streicher, Werner W.;Sumida, John P.;Swygert, Sarah G.;Szczepanowski, Roman H.;Tessmer, Ingrid;Toth, Ronald T.;Tripathy, Ashutosh;Uchiyama, Susumu;Uebel, Stephan F. W.;Unzai, Satoru;Gruber, Anna Vitlin;von Hippel, Peter H.;Wandrey, Christine;Wang, Szu-Huan;Weitzel, Steven E.;Wielgus-Kutrowska, Beata;Wolberger, Cynthia;Wolff, Martin;Wright, Edward;Wu, Yu-Sung;Wubben, Jacinta M.;Schuck, Peter

    2017-01-01

    Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tool...

  4. ACCESS, Absolute Color Calibration Experiment for Standard Stars: Integration, Test, and Ground Performance

    Science.gov (United States)

    Kaiser, Mary Elizabeth; Morris, Matthew; Aldoroty, Lauren; Kurucz, Robert; McCandliss, Stephan; Rauscher, Bernard; Kimble, Randy; Kruk, Jeffrey; Wright, Edward L.; Feldman, Paul; Riess, Adam; Gardner, Jonathon; Bohlin, Ralph; Deustua, Susana; Dixon, Van; Sahnow, David J.; Perlmutter, Saul

    2018-01-01

    Establishing improved spectrophotometric standards is important for a broad range of missions and is relevant to many astrophysical problems. Systematic errors associated with astrophysical data used to probe fundamental astrophysical questions, such as SNeIa observations used to constrain dark energy theories, now exceed the statistical errors associated with merged databases of these measurements. ACCESS, “Absolute Color Calibration Experiment for Standard Stars”, is a series of rocket-borne sub-orbital missions and ground-based experiments designed to enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35‑1.7μm bandpass. To achieve this goal ACCESS (1) observes HST/ Calspec stars (2) above the atmosphere to eliminate telluric spectral contaminants (e.g. OH) (3) using a single optical path and (HgCdTe) detector (4) that is calibrated to NIST laboratory standards and (5) monitored on the ground and in-flight using a on-board calibration monitor. The observations are (6) cross-checked and extended through the generation of stellar atmosphere models for the targets. The ACCESS telescope and spectrograph have been designed, fabricated, and integrated. Subsystems have been tested. Performance results for subsystems, operations testing, and the integrated spectrograph will be presented. NASA sounding rocket grant NNX17AC83G supports this work.

  5. 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.

  6. Absolute calibration of space-resolving soft X-ray spectrograph for plasma diagnostics

    CERN Document Server

    Yoshikawa, M; Kawamori, E; Watanabe, Y; Watabe, C; Yamaguchi, N; Tamano, T

    2001-01-01

    A grazing incidence flat-field soft X-ray (20-350 A) spectrograph was constructed and applied for impurity diagnostics in the GAMMA 10 fusion plasma. The spectrograph consisted of a limited height entrance slit, an aberration-corrected concave grating, a microchannel-plate intensified detector and an instant camera/a high speed solid state camera. An absolute calibration experiment for the SX spectrograph was performed at the Photon Factory in the High Energy Accelerator Research Organization with monitoring the incident synchrotron beam intensity by using an absolutely calibrated XUV silicon photodiode. From the results of absolute calibration of the spectrograph, the radiation loss from the plasma was obtained.

  7. Absolute calibration of space-resolving soft X-ray spectrograph for plasma diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, M. E-mail: yosikawa@prc.tsukuba.ac.jp; Okamoto, Y.; Kawamori, E.; Watanabe, Y.; Watabe, C.; Yamaguchi, N.; Tamano, T

    2001-07-21

    A grazing incidence flat-field soft X-ray (20-350 A) spectrograph was constructed and applied for impurity diagnostics in the GAMMA 10 fusion plasma. The spectrograph consisted of a limited height entrance slit, an aberration-corrected concave grating, a microchannel-plate intensified detector and an instant camera/a high speed solid state camera. An absolute calibration experiment for the SX spectrograph was performed at the Photon Factory in the High Energy Accelerator Research Organization with monitoring the incident synchrotron beam intensity by using an absolutely calibrated XUV silicon photodiode. From the results of absolute calibration of the spectrograph, the radiation loss from the plasma was obtained.

  8. A comparison of absolute calibrations of a radiation thermometer based on a monochromator and a tunable source

    Energy Technology Data Exchange (ETDEWEB)

    Keawprasert, T. [National Institute of Metrology Thailand, Pathum thani (Thailand); Anhalt, K.; Taubert, D. R.; Sperling, A.; Schuster, M.; Nevas, S. [Physikalisch Technische Bundesanstalt, Braunschweig and Berlin (Germany)

    2013-09-11

    An LP3 radiation thermometer was absolutely calibrated at a newly developed monochromator-based set-up and the TUneable Lasers in Photometry (TULIP) facility of PTB in the wavelength range from 400 nm to 1100 nm. At both facilities, the spectral radiation of the respective sources irradiates an integrating sphere, thus generating uniform radiance across its precision aperture. The spectral irradiance of the integrating sphere is determined via an effective area of a precision aperture and a Si trap detector, traceable to the primary cryogenic radiometer of PTB. Due to the limited output power from the monochromator, the absolute calibration was performed with the measurement uncertainty of 0.17 % (k= 1), while the respective uncertainty at the TULIP facility is 0.14 %. Calibration results obtained by the two facilities were compared in terms of spectral radiance responsivity, effective wavelength and integral responsivity. It was found that the measurement results in integral responsivity at the both facilities are in agreement within the expanded uncertainty (k= 2). To verify the calibration accuracy, the absolutely calibrated radiation thermometer was used to measure the thermodynamic freezing temperatures of the PTB gold fixed-point blackbody.

  9. A comparison of absolute calibrations of a radiation thermometer based on a monochromator and a tunable source

    International Nuclear Information System (INIS)

    Keawprasert, T.; Anhalt, K.; Taubert, D. R.; Sperling, A.; Schuster, M.; Nevas, S.

    2013-01-01

    An LP3 radiation thermometer was absolutely calibrated at a newly developed monochromator-based set-up and the TUneable Lasers in Photometry (TULIP) facility of PTB in the wavelength range from 400 nm to 1100 nm. At both facilities, the spectral radiation of the respective sources irradiates an integrating sphere, thus generating uniform radiance across its precision aperture. The spectral irradiance of the integrating sphere is determined via an effective area of a precision aperture and a Si trap detector, traceable to the primary cryogenic radiometer of PTB. Due to the limited output power from the monochromator, the absolute calibration was performed with the measurement uncertainty of 0.17 % (k= 1), while the respective uncertainty at the TULIP facility is 0.14 %. Calibration results obtained by the two facilities were compared in terms of spectral radiance responsivity, effective wavelength and integral responsivity. It was found that the measurement results in integral responsivity at the both facilities are in agreement within the expanded uncertainty (k= 2). To verify the calibration accuracy, the absolutely calibrated radiation thermometer was used to measure the thermodynamic freezing temperatures of the PTB gold fixed-point blackbody

  10. On the absolute calibration of SO2 cameras

    Directory of Open Access Journals (Sweden)

    P. Lübcke

    2013-03-01

    Full Text Available Sulphur dioxide emission rate measurements are an important tool for volcanic monitoring and eruption risk assessment. The SO2 camera technique remotely measures volcanic emissions by analysing the ultraviolet absorption of SO2 in a narrow spectral window between 300 and 320 nm using solar radiation scattered in the atmosphere. The SO2 absorption is selectively detected by mounting band-pass interference filters in front of a two-dimensional, UV-sensitive CCD detector. One important step for correct SO2 emission rate measurements that can be compared with other measurement techniques is a correct calibration. This requires conversion from the measured optical density to the desired SO2 column density (CD. The conversion factor is most commonly determined by inserting quartz cells (cuvettes with known amounts of SO2 into the light path. Another calibration method uses an additional narrow field-of-view Differential Optical Absorption Spectroscopy system (NFOV-DOAS, which measures the column density simultaneously in a small area of the camera's field-of-view. This procedure combines the very good spatial and temporal resolution of the SO2 camera technique with the more accurate column densities obtainable from DOAS measurements. This work investigates the uncertainty of results gained through the two commonly used, but quite different, calibration methods (DOAS and calibration cells. Measurements with three different instruments, an SO2 camera, a NFOV-DOAS system and an Imaging DOAS (I-DOAS, are presented. We compare the calibration-cell approach with the calibration from the NFOV-DOAS system. The respective results are compared with measurements from an I-DOAS to verify the calibration curve over the spatial extent of the image. The results show that calibration cells, while working fine in some cases, can lead to an overestimation of the SO2 CD by up to 60% compared with CDs from the DOAS measurements. Besides these errors of calibration

  11. Systematic Calibration for Ultra-High Accuracy Inertial Measurement Units

    Directory of Open Access Journals (Sweden)

    Qingzhong Cai

    2016-06-01

    Full Text Available An inertial navigation system (INS has been widely used in challenging GPS environments. With the rapid development of modern physics, an atomic gyroscope will come into use in the near future with a predicted accuracy of 5 × 10−6°/h or better. However, existing calibration methods and devices can not satisfy the accuracy requirements of future ultra-high accuracy inertial sensors. In this paper, an improved calibration model is established by introducing gyro g-sensitivity errors, accelerometer cross-coupling errors and lever arm errors. A systematic calibration method is proposed based on a 51-state Kalman filter and smoother. Simulation results show that the proposed calibration method can realize the estimation of all the parameters using a common dual-axis turntable. Laboratory and sailing tests prove that the position accuracy in a five-day inertial navigation can be improved about 8% by the proposed calibration method. The accuracy can be improved at least 20% when the position accuracy of the atomic gyro INS can reach a level of 0.1 nautical miles/5 d. Compared with the existing calibration methods, the proposed method, with more error sources and high order small error parameters calibrated for ultra-high accuracy inertial measurement units (IMUs using common turntables, has a great application potential in future atomic gyro INSs.

  12. Description and performance of the OGSE for VNIR absolute spectroradiometric calibration of MTG-I satellites

    Science.gov (United States)

    Glastre, W.; Marque, J.; Compain, E.; Deep, A.; Durand, Y.; Aminou, D. M. A.

    2017-09-01

    The Meteosat Third Generation (MTG) Programme is being realised through the well-established and successful Cooperation between EUMETSAT and ESA. It will ensure the future continuity of MSG with the capabilities to enhance nowcasting, global and regional numerical weather prediction, climate and atmospheric chemistry monitoring data from Geostationary Orbit. This will be achieved through a series of 6 satellites named MTG-I and MTG-S to bring to the meteorological community continuous high spatial, spectral and temporal resolution observations and geophysical parameters of the Earth based on sensors from the geo-stationary orbit. In particular, the imagery mission MTG-I will bring an improved continuation of the MSG satellites series with the Flexible Combined Imager (FCI) a broad spectral range (from UV to LWIR) with better spatial and spectral resolutions. The FCI will be able to take high spatial resolution pictures of the Earth within 8 VNIR and 8 IR channels. As one of the mission of this instrument is to provide a quantitative analysis of atmosphere compounds, the absolute observed radiance needs to be known with a specified accuracy for VNIR as low as to 5% at k=3 over its full dynamic. While the FCI is regularly recalibrated every 6 month at equinoxes, it is however requiring initial ground calibration for the beginning of its mission. The Multi Optical Test Assembly (MOTA) is one of the Optical Ground Support Equipment (OGSE) dedicated to various missions necessary for the integration of the FCI . This equipment, provided by Bertin Technologies, will be delivered to TAS-F by the end of 2016. One of its mission, is the on-ground absolute calibration of VNIR channels. In order to handle this, the MOTA will be placed in front of the FCI under representative vacuum conditions and will be able to project a perfectly known, calibrated radiance level within the full dynamic of FCI instrument. The main difficulty is the very demanding calibration level with

  13. On the absolute calibration of SO2 cameras

    Science.gov (United States)

    Lübcke, Peter; Bobrowski, Nicole; Illing, Sebastian; Kern, Christoph; Alvarez Nieves, Jose Manuel; Vogel, Leif; Zielcke, Johannes; Delgados Granados, Hugo; Platt, Ulrich

    2013-01-01

    Sulphur dioxide emission rate measurements are an important tool for volcanic monitoring and eruption risk assessment. The SO2 camera technique remotely measures volcanic emissions by analysing the ultraviolet absorption of SO2 in a narrow spectral window between 300 and 320 nm using solar radiation scattered in the atmosphere. The SO2 absorption is selectively detected by mounting band-pass interference filters in front of a two-dimensional, UV-sensitive CCD detector. One important step for correct SO2 emission rate measurements that can be compared with other measurement techniques is a correct calibration. This requires conversion from the measured optical density to the desired SO2 column density (CD). The conversion factor is most commonly determined by inserting quartz cells (cuvettes) with known amounts of SO2 into the light path. Another calibration method uses an additional narrow field-of-view Differential Optical Absorption Spectroscopy system (NFOVDOAS), which measures the column density simultaneously in a small area of the camera’s field-of-view. This procedure combines the very good spatial and temporal resolution of the SO2 camera technique with the more accurate column densities obtainable from DOAS measurements.

  14. The Absolute, Relative and Multi-Wavelength Calibration of the Pierre Auger Observatory Fluorescence Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Knapik, R.; Bauleo, P.; Becker, B.R.; Brack, J.; Caruso, R.; Fratte, C.Delle; Dorofeev, A.; Harton, J.; Insolia, A.; Matthews, J.A.J.; Menshikov, A.

    2007-08-01

    Absolute calibration of the Pierre Auger Observatory fluorescence detectors uses a 375 nm light source at the telescope aperture. This end-to-end technique accounts for the combined effects of all detector components in a single measurement. The relative response has been measured at wavelengths of 320, 337, 355, 380 and 405 nm, defining a spectral response curve which has been normalized to the absolute calibration. Before and after each night of data taking a relative calibration of the phototubes is performed. This relative calibration is used to track both short and long term changes in the detector's response. A cross check of the calibration in some phototubes is performed using an independent laser technique. Overall uncertainties, current results and future plans are discussed.

  15. Absolute intensity calibration of the 32-channel heterodyne radiometer on experimental advanced superconducting tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X.; Zhao, H. L.; Liu, Y., E-mail: liuyong@ipp.ac.cn; Li, E. Z.; Han, X.; Ti, A.; Hu, L. Q.; Zhang, X. D. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Domier, C. W.; Luhmann, N. C. [Department of Electrical and Computer Engineering, University of California at Davis, Davis, California 95616 (United States)

    2014-09-15

    This paper presents the results of the in situ absolute intensity calibration for the 32-channel heterodyne radiometer on the experimental advanced superconducting tokamak. The hot/cold load method is adopted, and the coherent averaging technique is employed to improve the signal to noise ratio. Measured spectra and electron temperature profiles are compared with those from an independent calibrated Michelson interferometer, and there is a relatively good agreement between the results from the two different systems.

  16. Electron cyclotron emission measurements on JET: Michelson interferometer, new absolute calibration, and determination of electron temperature.

    Science.gov (United States)

    Schmuck, S; Fessey, J; Gerbaud, T; Alper, B; Beurskens, M N A; de la Luna, E; Sirinelli, A; Zerbini, M

    2012-12-01

    At the fusion experiment JET, a Michelson interferometer is used to measure the spectrum of the electron cyclotron emission in the spectral range 70-500 GHz. The interferometer is absolutely calibrated using the hot/cold technique and, in consequence, the spatial profile of the plasma electron temperature is determined from the measurements. The current state of the interferometer hardware, the calibration setup, and the analysis technique for calibration and plasma operation are described. A new, full-system, absolute calibration employing continuous data acquisition has been performed recently and the calibration method and results are presented. The noise level in the measurement is very low and as a result the electron cyclotron emission spectrum and thus the spatial profile of the electron temperature are determined to within ±5% and in the most relevant region to within ±2%. The new calibration shows that the absolute response of the system has decreased by about 15% compared to that measured previously and possible reasons for this change are presented. Temperature profiles measured with the Michelson interferometer are compared with profiles measured independently using Thomson scattering diagnostics, which have also been recently refurbished and recalibrated, and agreement within experimental uncertainties is obtained.

  17. Absolute calibration method for nanosecond-resolved, time-streaked, fiber optic light collection, spectroscopy systems

    International Nuclear Information System (INIS)

    Johnston, Mark D.; Oliver, Bryan V.; Droemer, Darryl W.; Frogget, Brent; Crain, Marlon D.; Maron, Yitzhak

    2012-01-01

    This paper describes a convenient and accurate method to calibrate fast ( 2 /steradian/nm). Error analysis shows this method to be accurate to within +/– 20%, which represents a high level of accuracy for this type of measurement.

  18. Electron cyclotron emission measurements on JET: Michelson interferometer, new absolute calibration, and determination of electron temperature

    NARCIS (Netherlands)

    Schmuck, S.; Fessey, J.; Gerbaud, T.; Alper, B.; Beurskens, M. N. A.; de la Luna, E.; Sirinelli, A.; Zerbini, M.

    2012-01-01

    At the fusion experiment JET, a Michelson interferometer is used to measure the spectrum of the electron cyclotron emission in the spectral range 70-500 GHz. The interferometer is absolutely calibrated using the hot/cold technique and, in consequence, the spatial profile of the plasma electron

  19. Exact theory of optical tweezers and its application to absolute calibration

    DEFF Research Database (Denmark)

    Dutra, Rafael de Sousa; Viana, Nathan B.; Maia Neto, Paulo A.

    2017-01-01

    Optical tweezers have become a powerful tool for basic and applied research in cell biology. Here, we describe an experimentally verified theory for the trapping forces generated by optical tweezers based on first principles that allows absolute calibration. For pedagogical reasons, the steps tha...

  20. EMISAR: An Absolutely Calibrated Polarimetric L- and C-band SAR

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz; Skou, Niels; Dall, Jørgen

    1998-01-01

    and low cross-polar contamination. Digital technology has been utilized to realize a flexible and highly stable radar with variable resolution, swath width, and imaging geometry. Thermal control and several calibration loops have been built into the system to ensure system stability and absolute......EMISAR is a high-resolution (2×2 m), fully polarimetric, dual-frequency (L- and C-band) synthetic aperture radar (SAR) system designed for remote-sensing applications. The SAR is operated at high altitudes on a Gulfstream G-3 jet aircraft. The system is very well calibrated and has low sidelobes...... calibration. Accurately measured antenna gains and radiation patterns are included in the calibration. The processing system is developed to support data calibration, which is the key to most of the current applications. Recent interferometric enhancements are important for many scientific applications...

  1. Preliminary results of absolute wavelength calibration of imaging X-ray crystal spectrometer on EAST

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Xiayun [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Wang, Fudi [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Chen, Jun [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Lyu, Bo, E-mail: blu@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Li, Yingying; Fu, Jia; Xu, Liqing [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Shi, Yuejiang [University of Science and Technology of China, Hefei 230026 (China); Department of Nuclear Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Ye, Minyou [University of Science and Technology of China, Hefei 230026 (China); Wan, Baonian [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2015-10-15

    Highlights: • The absolute wavelength calibration method for X-ray crystal spectrometer using X-ray fluorescence of the appropriate materials was first tested on EAST, and the preliminary experimental results were obtained. • The experimental results were thoroughly discussed and suggestion for further improvements of the experimental arrangement was proposed. • Rotation calibration of X-ray crystal spectrometer on EAST using MHD frequency was presented when the absolute wavelength calibration method is unavailable currently. - Abstract: Imaging X-ray crystal spectrometers (XCS) are currently operating on several major tokamaks to provide profiles of ion temperature and rotation velocity. In order to acquire absolute rotation velocity, several indirect methods were pursued previously, however the direct and effective method is to use known X-ray lines for wavelength calibration. One way to produce standard spectral lines is X-ray fluorescence, which could be excited by X-rays from tokamak plasmas. As part of the upgrade of XCS system on EAST, wavelength calibration was studied using cadmium's L-shell lines, namely Lα{sub 1} line (3.9564 Å) and Lα{sub 2} line (3.9650 Å) as the reference wavelength. The Geant 4 code was used to optimize foil thickness to achieve a reasonable X-ray fluorescence intensity. The Cd foil was placed between the beryllium window and crystal and could be retracted to provide in situ wavelength calibration. The detailed arrangement and preliminary wavelength calibration results of imaging X-ray crystal spectrometer on EAST are presented, plus the calibration using MHD frequency.

  2. A Multilaboratory Comparison of Calibration Accuracy and the Performance of External References in Analytical Ultracentrifugation

    KAUST Repository

    Zhao, Huaying

    2015-05-21

    Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies.

  3. A multilaboratory comparison of calibration accuracy and the performance of external references in analytical ultracentrifugation.

    Science.gov (United States)

    Zhao, Huaying; Ghirlando, Rodolfo; Alfonso, Carlos; Arisaka, Fumio; Attali, Ilan; Bain, David L; Bakhtina, Marina M; Becker, Donald F; Bedwell, Gregory J; Bekdemir, Ahmet; Besong, Tabot M D; Birck, Catherine; Brautigam, Chad A; Brennerman, William; Byron, Olwyn; Bzowska, Agnieszka; Chaires, Jonathan B; Chaton, Catherine T; Cölfen, Helmut; Connaghan, Keith D; Crowley, Kimberly A; Curth, Ute; Daviter, Tina; Dean, William L; Díez, Ana I; Ebel, Christine; Eckert, Debra M; Eisele, Leslie E; Eisenstein, Edward; England, Patrick; Escalante, Carlos; Fagan, Jeffrey A; Fairman, Robert; Finn, Ron M; Fischle, Wolfgang; de la Torre, José García; Gor, Jayesh; Gustafsson, Henning; Hall, Damien; Harding, Stephen E; Cifre, José G Hernández; Herr, Andrew B; Howell, Elizabeth E; Isaac, Richard S; Jao, Shu-Chuan; Jose, Davis; Kim, Soon-Jong; Kokona, Bashkim; Kornblatt, Jack A; Kosek, Dalibor; Krayukhina, Elena; Krzizike, Daniel; Kusznir, Eric A; Kwon, Hyewon; Larson, Adam; Laue, Thomas M; Le Roy, Aline; Leech, Andrew P; Lilie, Hauke; Luger, Karolin; Luque-Ortega, Juan R; Ma, Jia; May, Carrie A; Maynard, Ernest L; Modrak-Wojcik, Anna; Mok, Yee-Foong; Mücke, Norbert; Nagel-Steger, Luitgard; Narlikar, Geeta J; Noda, Masanori; Nourse, Amanda; Obsil, Tomas; Park, Chad K; Park, Jin-Ku; Pawelek, Peter D; Perdue, Erby E; Perkins, Stephen J; Perugini, Matthew A; Peterson, Craig L; Peverelli, Martin G; Piszczek, Grzegorz; Prag, Gali; Prevelige, Peter E; Raynal, Bertrand D E; Rezabkova, Lenka; Richter, Klaus; Ringel, Alison E; Rosenberg, Rose; Rowe, Arthur J; Rufer, Arne C; Scott, David J; Seravalli, Javier G; Solovyova, Alexandra S; Song, Renjie; Staunton, David; Stoddard, Caitlin; Stott, Katherine; Strauss, Holger M; Streicher, Werner W; Sumida, John P; Swygert, Sarah G; Szczepanowski, Roman H; Tessmer, Ingrid; Toth, Ronald T; Tripathy, Ashutosh; Uchiyama, Susumu; Uebel, Stephan F W; Unzai, Satoru; Gruber, Anna Vitlin; von Hippel, Peter H; Wandrey, Christine; Wang, Szu-Huan; Weitzel, Steven E; Wielgus-Kutrowska, Beata; Wolberger, Cynthia; Wolff, Martin; Wright, Edward; Wu, Yu-Sung; Wubben, Jacinta M; Schuck, Peter

    2015-01-01

    Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies.

  4. A Multilaboratory Comparison of Calibration Accuracy and the Performance of External References in Analytical Ultracentrifugation

    Science.gov (United States)

    Zhao, Huaying; Ghirlando, Rodolfo; Alfonso, Carlos; Arisaka, Fumio; Attali, Ilan; Bain, David L.; Bakhtina, Marina M.; Becker, Donald F.; Bedwell, Gregory J.; Bekdemir, Ahmet; Besong, Tabot M. D.; Birck, Catherine; Brautigam, Chad A.; Brennerman, William; Byron, Olwyn; Bzowska, Agnieszka; Chaires, Jonathan B.; Chaton, Catherine T.; Cölfen, Helmut; Connaghan, Keith D.; Crowley, Kimberly A.; Curth, Ute; Daviter, Tina; Dean, William L.; Díez, Ana I.; Ebel, Christine; Eckert, Debra M.; Eisele, Leslie E.; Eisenstein, Edward; England, Patrick; Escalante, Carlos; Fagan, Jeffrey A.; Fairman, Robert; Finn, Ron M.; Fischle, Wolfgang; de la Torre, José García; Gor, Jayesh; Gustafsson, Henning; Hall, Damien; Harding, Stephen E.; Cifre, José G. Hernández; Herr, Andrew B.; Howell, Elizabeth E.; Isaac, Richard S.; Jao, Shu-Chuan; Jose, Davis; Kim, Soon-Jong; Kokona, Bashkim; Kornblatt, Jack A.; Kosek, Dalibor; Krayukhina, Elena; Krzizike, Daniel; Kusznir, Eric A.; Kwon, Hyewon; Larson, Adam; Laue, Thomas M.; Le Roy, Aline; Leech, Andrew P.; Lilie, Hauke; Luger, Karolin; Luque-Ortega, Juan R.; Ma, Jia; May, Carrie A.; Maynard, Ernest L.; Modrak-Wojcik, Anna; Mok, Yee-Foong; Mücke, Norbert; Nagel-Steger, Luitgard; Narlikar, Geeta J.; Noda, Masanori; Nourse, Amanda; Obsil, Tomas; Park, Chad K.; Park, Jin-Ku; Pawelek, Peter D.; Perdue, Erby E.; Perkins, Stephen J.; Perugini, Matthew A.; Peterson, Craig L.; Peverelli, Martin G.; Piszczek, Grzegorz; Prag, Gali; Prevelige, Peter E.; Raynal, Bertrand D. E.; Rezabkova, Lenka; Richter, Klaus; Ringel, Alison E.; Rosenberg, Rose; Rowe, Arthur J.; Rufer, Arne C.; Scott, David J.; Seravalli, Javier G.; Solovyova, Alexandra S.; Song, Renjie; Staunton, David; Stoddard, Caitlin; Stott, Katherine; Strauss, Holger M.; Streicher, Werner W.; Sumida, John P.; Swygert, Sarah G.; Szczepanowski, Roman H.; Tessmer, Ingrid; Toth, Ronald T.; Tripathy, Ashutosh; Uchiyama, Susumu; Uebel, Stephan F. W.; Unzai, Satoru; Gruber, Anna Vitlin; von Hippel, Peter H.; Wandrey, Christine; Wang, Szu-Huan; Weitzel, Steven E.; Wielgus-Kutrowska, Beata; Wolberger, Cynthia; Wolff, Martin; Wright, Edward; Wu, Yu-Sung; Wubben, Jacinta M.; Schuck, Peter

    2015-01-01

    Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies. PMID:25997164

  5. A multilaboratory comparison of calibration accuracy and the performance of external references in analytical ultracentrifugation.

    Directory of Open Access Journals (Sweden)

    Huaying Zhao

    Full Text Available Analytical ultracentrifugation (AUC is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188 S (4.4%. After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%. In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies.

  6. A first in-flight absolute calibration of the Chilean Earth Observation Satellite

    Science.gov (United States)

    Mattar, C.; Hernández, J.; Santamaría-Artigas, A.; Durán-Alarcón, C.; Olivera-Guerra, L.; Inzunza, M.; Tapia, D.; Escobar-lavín, E.

    2014-06-01

    This work describes the first in-flight absolute calibration of the "Sistema Satelital para la Observación de la Tierra" (SSOT or Fasat-C). It was performed on January 29th 2013 at Antumapu site located in the southern area of Santiago, Chile. A description of the procedure is presented which includes both ground measurement and atmospheric characterization. The Chilean satellite for Earth observation carries on board a "New AstroSat Optical Modular Instrument" (NAOMI) high-resolution pushbroom imager which provides a 1.45 m ground sampling distance in the panchromatic (0.455-0.744 μm) channel and a 5.8 m ground sampling distance for the green (0.455-0.52 μm), blue (0.528-0.588 μm), red (0.625-0.695 μm) and near-infrared (0.758-0.881 μm) channels from a 620 km orbit. Radiometric calibration was carried out in order to estimate the land leaving radiance and bidirectional reflectance at the top of the atmosphere. To correct the reflectance data for atmospheric effects, the Second Simulation of a Satellite Signal in the Solar Spectrum (6S) code was used. Aerosol Optical Depth (AOD), water vapor and ozone content were obtained from MOD04, MOD05 and MOD07 products respectively, which are derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) data. Statistical results such as BIAS, SIGMA and RMSE were calculated for the comparison between surface reflectance values and in situ measurements. Results show that the overall accuracy of the atmospherically corrected surface reflectance calculated from Fasat-C imagery can be estimated to around ±5%, with a R2 coefficient of 0.939 between atmospherically corrected reflectance values and in situ measurements. The atmospheric correction applied in this work by combining MODIS data and the 6S radiative transfer code could be used for further calibration of the Fasat-C images, although in situ atmospheric irradiance measurements are necessary to estimate reliable values of surface reflectance. Future

  7. Absolute calibration of neutron detectors on the C-2U advanced beam-driven FRC

    Energy Technology Data Exchange (ETDEWEB)

    Magee, R. M., E-mail: rmagee@trialphaenergy.com; Clary, R.; Korepanov, S.; Jauregui, F.; Allfrey, I.; Garate, E.; Valentine, T.; Smirnov, A. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States)

    2016-11-15

    In the C-2U fusion energy experiment, high power neutral beam injection creates a large fast ion population that sustains a field-reversed configuration (FRC) plasma. The diagnosis of the fast ion pressure in these high-performance plasmas is therefore critical, and the measurement of the flux of neutrons from the deuterium-deuterium (D-D) fusion reaction is well suited to the task. Here we describe the absolute, in situ calibration of scintillation neutron detectors via two independent methods: firing deuterium beams into a high density gas target and calibration with a 2 × 10{sup 7} n/s AmBe source. The practical issues of each method are discussed and the resulting calibration factors are shown to be in good agreement. Finally, the calibration factor is applied to C-2U experimental data where the measured neutron rate is found to exceed the classical expectation.

  8. Absolute mass scale calibration in the inverse problem of the physical theory of fireballs.

    Science.gov (United States)

    Kalenichenko, V. V.

    A method of the absolute mass scale calibration is suggested for solving the inverse problem of the physical theory of fireballs. The method is based on the data on the masses of the fallen meteorites whose fireballs have been photographed in their flight. The method may be applied to those fireballs whose bodies have not experienced considerable fragmentation during their destruction in the atmosphere and have kept their form well enough. Statistical analysis of the inverse problem solution for a sufficiently representative sample makes it possible to separate a subsample of such fireballs. The data on the Lost City and Innisfree meteorites are used to obtain calibration coefficients.

  9. Absolute calibration of the mass scale in the inverse problem of the physical theory of fireballs

    Science.gov (United States)

    Kalenichenko, V. V.

    1992-08-01

    A method of the absolute calibration of the mass scale is proposed for solving the inverse problem of the physical theory of fireballs. The method is based on data on the masses of fallen meteorites whose fireballs have been photographed in flight. The method can be applied to fireballs whose bodies have not experienced significant fragmentation during their flight in the atmosphere and have kept their shape relatively well. Data on the Lost City and Innisfree meteorites are used to calculate the calibration coefficients.

  10. The absolute radiometric calibration of the advanced very high resolution radiometer

    Science.gov (United States)

    Slater, P. N.; Teillet, P. M.; Ding, Y.

    1988-01-01

    An increasing number of remote sensing investigations require radiometrically calibrated imagery from NOAA Advanced Very High Resolution Radiation (AVHRR) sensors. Although a prelaunch calibration is done for these sensors, there is no capability for monitoring any changes in the in-flight absolute calibration for the visible and near infrared spectral channels. Hence, the possibility of using the reflectance-based method developed at White Sands for in-orbit calibration of LANDSAT Thematic Mapper (TM) and SPOT Haute Resolution Visible (HVR) data to calibrate the AVHRR sensor was investigated. Three diffrent approaches were considered: Method 1 - ground and atmospheric measurements and reference to another calibrated satellite sensor; Method 2 - ground and atmospheric measurements with no reference to another sensor; and Method 3 - no ground and atmospheric measurements but reference to another satellite sensor. The purpose is to describe an investigation on the use of Method 2 to calibrate NOAA-9 AVHRR channels 1 and 2 with the help of ground and atmospheric measurements at Rogers (dry) Lake, Edwards Air Force Base (EAFB) in the Mojave desert of California.

  11. The absolute radiometric calibration of the advanced very high resolution radiometer

    Science.gov (United States)

    Slater, P. N.; Teillet, P. M.; Ding, Y.

    1988-10-01

    An increasing number of remote sensing investigations require radiometrically calibrated imagery from NOAA Advanced Very High Resolution Radiation (AVHRR) sensors. Although a prelaunch calibration is done for these sensors, there is no capability for monitoring any changes in the in-flight absolute calibration for the visible and near infrared spectral channels. Hence, the possibility of using the reflectance-based method developed at White Sands for in-orbit calibration of LANDSAT Thematic Mapper (TM) and SPOT Haute Resolution Visible (HVR) data to calibrate the AVHRR sensor was investigated. Three diffrent approaches were considered: Method 1 - ground and atmospheric measurements and reference to another calibrated satellite sensor; Method 2 - ground and atmospheric measurements with no reference to another sensor; and Method 3 - no ground and atmospheric measurements but reference to another satellite sensor. The purpose is to describe an investigation on the use of Method 2 to calibrate NOAA-9 AVHRR channels 1 and 2 with the help of ground and atmospheric measurements at Rogers (dry) Lake, Edwards Air Force Base (EAFB) in the Mojave desert of California.

  12. The CLARA/NORSAT-1 solar absolute radiometer: instrument design, characterization and calibration

    Science.gov (United States)

    Walter, Benjamin; Levesque, Pierre-Luc; Kopp, Greg; Andersen, Bo; Beck, Ivo; Finsterle, Wolfgang; Gyo, Manfred; Heuerman, Karl; Koller, Silvio; Mingard, Nathan; Remesal Oliva, Alberto; Pfiffner, Daniel; Soder, Ricco; Spescha, Marcel; Suter, Markus; Schmutz, Werner

    2017-10-01

    The compact lightweight absolute radiometer (CLARA) experiment aims at measuring the total solar irradiance (TSI) in space and is scheduled to fly on the Norwegian NORSAT-1 micro satellite. The CLARA experiment will contribute to the long term monitoring of the TSI variability to support the analysis of potential long term trends in the Sun’s variability. CLARA is traceable to the National Institute of Standards and Technology radiometric scale and will provide further evidence for the TSI value on an absolute scale. In this paper we present the design, characterization, and calibration details of the CLARA instrument. The combined measurement uncertainty for the calibrated SI-traceable CLARA flight instrument is 567-912 ppm (k  =  1) depending on the measuring channel.

  13. Absolute calibration of photon-number-resolving detectors with an analog output using twin beams

    Science.gov (United States)

    Peřina, Jan; Haderka, Ondřej; Allevi, Alessia; Bondani, Maria

    2014-01-01

    A method for absolute calibration of a photon-number resolving detector producing analog signals as the output is developed using a twin beam. The method gives both analog-to-digital conversion parameters and quantum detection efficiency for the photon fields. Characteristics of the used twin beam are also obtained. A simplified variant of the method applicable to fields with high signal to noise ratios and suitable for more intense twin beams is suggested.

  14. Absolute in situ energy calibration of luminosity calorimeters in the DELPHI experiment at LEP

    International Nuclear Information System (INIS)

    Bugge, L.; Dam, M.; Read, A.L.; Myrheim, J.; Skjevling, G.

    1993-01-01

    Methods to perform the absolute energy calibration of DELPHI's Small Angle Tagger luminosity calorimeters at LEP are presented and compared. The input was small angle Bhabha scattering events. A significant nonlinearity in the response of the calorimeters was observed. The conjugate gradient method was applied to solve the least squares problem. This method is particularly useful for least squares problems which are large, ill-behaved or even singular, and for cases with a sparse coefficient matrix. (orig.)

  15. Absolute calibration of photon-number-resolving detectors with an analog output using twin beams

    Energy Technology Data Exchange (ETDEWEB)

    Peřina, Jan, E-mail: jan.perina.jr@upol.cz [RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics AS CR, 17. listopadu 12, 77146 Olomouc (Czech Republic); Haderka, Ondřej [Joint Laboratory of Optics of Palacký University and Institute of Physics AS CR, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Allevi, Alessia [Dipartimento di Scienza e Alta Tecnologia, Università degli Studi dell' Insubria, I-22100 Como (Italy); Bondani, Maria [Istituto di Fotonica e Nanotecnologie, CNR-IFN, I-22100 Como (Italy)

    2014-01-27

    A method for absolute calibration of a photon-number resolving detector producing analog signals as the output is developed using a twin beam. The method gives both analog-to-digital conversion parameters and quantum detection efficiency for the photon fields. Characteristics of the used twin beam are also obtained. A simplified variant of the method applicable to fields with high signal to noise ratios and suitable for more intense twin beams is suggested.

  16. On the precision of absolute sensitivity calibration and specifics of spectroscopic quantities interpretation in tokamaks

    Czech Academy of Sciences Publication Activity Database

    Naydenkova, Diana; Weinzettl, Vladimír; Stöckel, Jan; Matějíček, Jiří

    2014-01-01

    Roč. 53, č. 34 (2014), s. 8123-8130 ISSN 1559-128X R&D Projects: GA ČR(CZ) GA14-12837S Institutional support: RVO:61389021 Keywords : Spectroscopy * emission * spectrometers * absolute calibration Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.784, year: 2014 http://dx.doi.org/10.1364/AO.53.008123

  17. Calibration of Robot Reference Frames for Enhanced Robot Positioning Accuracy

    OpenAIRE

    Cheng, Frank Shaopeng

    2008-01-01

    This chapter discussed the importance and methods of conducting robot workcell calibration for enhancing the accuracy of the robot TCP positions in industrial robot applications. It shows that the robot frame transformations define the robot geometric parameters such as joint position variables, link dimensions, and joint offsets in an industrial robot system. The D-H representation allows the robot designer to model the robot motion geometry with the four standard D-H parameters. The robot k...

  18. Flow rate calibration I: a novel approach for performing absolute cell counts.

    Science.gov (United States)

    Storie, Ian; Sawle, Alex; Goodfellow, Karen; Whitby, Liam; Granger, Vivian; Reilly, John T; Barnett, David

    2003-09-01

    Reports suggest that flow rate (FR) is constant on bench top flow cytometers. Therefore, if FR is constant, the volume acquired in a fixed time period will also be constant, enabling absolute leucocyte counting using flow rate calibration (FRC). FR stability was ascertained on a standard FACSCalibur by counting TruCount beads suspended in phosphate buffered saline over 120 s. Studies using two lysing solutions (FACS lysing solution and PharM Lyse) and corresponding sample lysates established a lysing solution calibration factor (CF). Absolute CD4(+) T-lymphocyte counts on 10 peripheral blood samples determined using FRC were compared with the predicate method TruCount/MultiTEST, incorporating MultiSET software. Linearity studies were also performed at three different flow rates. A high degree of linearity over a wide range of counts (50 to >1,600 CD4(+) T lymphocytes/microl) at all three pressures was observed. Importantly, there was no significant difference from the predicate method when appropriate lysing solution CF was used. Using a simple calibration procedure and incorporation of an appropriate lysing solution CF, we show that FRC can easily be performed. The technical details that underpin this novel approach for absolute leucocyte enumeration are provided. Copyright 2003 Wiley-Liss, Inc.

  19. Empirical photometric calibration of the Gaia red clump: Colours, effective temperature, and absolute magnitude

    Science.gov (United States)

    Ruiz-Dern, L.; Babusiaux, C.; Arenou, F.; Turon, C.; Lallement, R.

    2018-01-01

    Context. Gaia Data Release 1 allows the recalibration of standard candles such as the red clump stars. To use those stars, they first need to be accurately characterised. In particular, colours are needed to derive interstellar extinction. As no filter is available for the first Gaia data release and to avoid the atmosphere model mismatch, an empirical calibration is unavoidable. Aims: The purpose of this work is to provide the first complete and robust photometric empirical calibration of the Gaia red clump stars of the solar neighbourhood through colour-colour, effective temperature-colour, and absolute magnitude-colour relations from the Gaia, Johnson, 2MASS, HIPPARCOS, Tycho-2, APASS-SLOAN, and WISE photometric systems, and the APOGEE DR13 spectroscopic temperatures. Methods: We used a 3D extinction map to select low reddening red giants. To calibrate the colour-colour and the effective temperature-colour relations, we developed a MCMC method that accounts for all variable uncertainties and selects the best model for each photometric relation. We estimated the red clump absolute magnitude through the mode of a kernel-based distribution function. Results: We provide 20 colour versus G-Ks relations and the first Teff versus G-Ks calibration. We obtained the red clump absolute magnitudes for 15 photometric bands with, in particular, MKs = (-1.606 ± 0.009) and MG = (0.495 ± 0.009) + (1.121 ± 0.128)(G-Ks-2.1). We present a dereddened Gaia-TGAS HR diagram and use the calibrations to compare its red clump and its red giant branch bump with Padova isochrones. Full Table A.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A116

  20. Absolute calibration of SARAL/AltiKa in Kavaratti during its initial calibration-validation phase

    Digital Repository Service at National Institute of Oceanography (India)

    Babu, K.N.; Shukla, A.K.; Suchandra, A.B.; ArunKumar, S.V.V.; Bonnefond, P.; Testut, L.; Mehra, P.; Laurain, O.

    ^te d’Azur – G�eoazur, Grasse, France 3Laboratoire d’Etudes en G�eophysique et Oc�eanographie Spatiales (LEGOS) UMR5566 (CNES/CNRS/IRD/UPS), Toulouse, France 4Littoral Environnement et Soci�et�es (LIENSS), Universit�e de La Rochelle- CNRS, La Rochelle.../AltiKa in Kavaratti During its Initial Calibration-Validation Phase K. N. BABU,1 A. K. SHUKLA,1 A. B. SUCHANDRA,1 S. V. V. ARUN KUMAR,1 P. BONNEFOND,2 L. TESTUT,3,4 P. MEHRA,5 AND O. LAURAIN2 1Space Applications Centre (ISRO), Ahmedabad, India 2Observatoire de La Co...

  1. Absolute Calibration of Si iRMs used for Measurements of Si Paleo-nutrient proxies

    Science.gov (United States)

    Vocke, R. D., Jr.; Rabb, S. A.

    2016-12-01

    Silicon isotope variations (reported as δ30Si and δ29Si, relative to NBS28) in silicic acid dissolved in ocean waters, in biogenic silica and in diatoms are extremely informative paleo-nutrient proxies. The resolution and comparability of such measurements depend on the quality of the isotopic Reference Materials (iRMs) defining the delta scale. We report new absolute Si isotopic measurements on the iRMs NBS28 (RM 8546 - Silica Sand), Diatomite, and Big Batch using the Avogadro measurement approach and comparing them with prior assessments of these iRMs. The Avogadro Si measurement technique was developed by the German Physikalish-Technische Bundesanstalt (PTB) to provide a precise and highly accurate method to measure absolute isotopic ratios in highly enriched 28Si (99.996%) material. These measurements are part of an international effort to redefine the kg and mole based on the Planck constant h and the Avogadro constant NA, respectively (Vocke et al., 2014 Metrologia 51, 361, Azuma et al., 2015 Metrologia 52 360). This approach produces absolute Si isotope ratio data with lower levels of uncertainty when compared to the traditional "Atomic Weights" method of absolute isotope ratio measurement calibration. This is illustrated in Fig. 1 where absolute Si isotopic measurements on SRM 990, separated by 40+ years of advances in instrumentation, are compared. The availability of this new technique does not say that absolute Si isotopic ratios are or ever will be better for normal Si isotopic measurements when seeking isotopic variations in nature, because they are not. However, by determining the absolute isotopic ratios of all the Si iRM scale artifacts, such iRMs become traceable to the metric system (SI); thereby automatically conferring on all the artifact-based δ30Si and δ29Si measurements traceability to the base SI unit, the mole. Such traceability should help reduce the potential of bias between different iRMs and facilitate the replacement of delta

  2. Absolute calibration of in vivo measurement systems using magnetic resonance imaging and Monte Carlo computations

    International Nuclear Information System (INIS)

    Mallett, M.W.

    1991-01-01

    Lawrence Livermore National Laboratory (LLNL) is currently investigating a new method for obtaining absolute calibration factors for radiation measurement systems used to measure internally deposited radionuclides in vivo. This method uses magnetic resonance imaging (MRI) to determine the anatomical makeup of an individual. A new MRI technique is also employed that is capable of resolving the fat and water content of the human tissue. This anatomical and biochemical information is used to model a mathematical phantom. Monte Carlo methods are then used to simulate the transport of radiation throughout the phantom. By modeling the detection equipment of the in vivo measurement system into the code, calibration factors are generated that are specific to the individual. Furthermore, this method eliminates the need for surrogate human structures in the calibration process. A demonstration of the proposed method is being performed using a fat/water matrix

  3. Absolute gain calibration system for the 349-pixel imaging element of the tactic telescope array

    International Nuclear Information System (INIS)

    Tickoo, A.K.; Dhar, V.K.; Venugopal, K.; Kaul, S.K.; Koul, R.; Bhatt, N.; Goyal, H.C.; Bhat, C.L.

    2001-01-01

    The imaging Element of the 4-element TACTIC telescope array has been in operation at Mt. Abu since 1997, for carrying detailed investigations of gamma-ray sources in the TeV energy range. In order to characterize the progenitor particle (Gamma-ray/cosmic-ray), a relative gain calibration system, based on a high intensity LED, has been in operation. However, for calorimetric purposes, an absolute gain calibration system is necessary and has been developed for an on-line calibration of 4 out of 349-pixels of its imaging camera, using 241 Am based light pulsers. The details of the experimental set-up and the results obtained so far are presented in this paper. (author)

  4. Simple method for absolute calibration of geophones, seismometers, and other inertial vibration sensors

    International Nuclear Information System (INIS)

    Kann, Frank van; Winterflood, John

    2005-01-01

    A simple but powerful method is presented for calibrating geophones, seismometers, and other inertial vibration sensors, including passive accelerometers. The method requires no cumbersome or expensive fixtures such as shaker platforms and can be performed using a standard instrument commonly available in the field. An absolute calibration is obtained using the reciprocity property of the device, based on the standard mathematical model for such inertial sensors. It requires only simple electrical measurement of the impedance of the sensor as a function of frequency to determine the parameters of the model and hence the sensitivity function. The method is particularly convenient if one of these parameters, namely the suspended mass is known. In this case, no additional mechanical apparatus is required and only a single set of impedance measurements yields the desired calibration function. Moreover, this measurement can be made with the device in situ. However, the novel and most powerful aspect of the method is its ability to accurately determine the effective suspended mass. For this, the impedance measurement is made with the device hanging from a simple spring or flexible cord (depending on the orientation of its sensitive axis). To complete the calibration, the device is weighed to determine its total mass. All the required calibration parameters, including the suspended mass, are then determined from a least-squares fit to the impedance as a function of frequency. A demonstration using both a 4.5 Hz geophone and a 1 Hz seismometer shows that the method can yield accurate absolute calibrations with an error of 0.1% or better, assuming no a priori knowledge of any parameters

  5. Precision and accuracy in the quantitative analysis of biological samples by accelerator mass spectrometry: application in microdose absolute bioavailability studies.

    Science.gov (United States)

    Gao, Lan; Li, Jing; Kasserra, Claudia; Song, Qi; Arjomand, Ali; Hesk, David; Chowdhury, Swapan K

    2011-07-15

    Determination of the pharmacokinetics and absolute bioavailability of an experimental compound, SCH 900518, following a 89.7 nCi (100 μg) intravenous (iv) dose of (14)C-SCH 900518 2 h post 200 mg oral administration of nonradiolabeled SCH 900518 to six healthy male subjects has been described. The plasma concentration of SCH 900518 was measured using a validated LC-MS/MS system, and accelerator mass spectrometry (AMS) was used for quantitative plasma (14)C-SCH 900518 concentration determination. Calibration standards and quality controls were included for every batch of sample analysis by AMS to ensure acceptable quality of the assay. Plasma (14)C-SCH 900518 concentrations were derived from the regression function established from the calibration standards, rather than directly from isotopic ratios from AMS measurement. The precision and accuracy of quality controls and calibration standards met the requirements of bioanalytical guidance (U.S. Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research, Center for Veterinary Medicine. Guidance for Industry: Bioanalytical Method Validation (ucm070107), May 2001. http://www.fda.gov/downloads/Drugs/GuidanceCompilanceRegulatoryInformation/Guidances/ucm070107.pdf ). The AMS measurement had a linear response range from 0.0159 to 9.07 dpm/mL for plasma (14)C-SCH 900158 concentrations. The CV and accuracy were 3.4-8.5% and 94-108% (82-119% for the lower limit of quantitation (LLOQ)), respectively, with a correlation coefficient of 0.9998. The absolute bioavailability was calculated from the dose-normalized area under the curve of iv and oral doses after the plasma concentrations were plotted vs the sampling time post oral dose. The mean absolute bioavailability of SCH 900518 was 40.8% (range 16.8-60.6%). The typical accuracy and standard deviation in AMS quantitative analysis of drugs from human plasma samples have been reported for the first time, and the impact of these

  6. Absolute Calibration of Si iRMs used for Si Paleo-nutrient proxies

    Science.gov (United States)

    Vocke, Robert; Rabb, Savelas

    2016-04-01

    The Avogadro Project is an ongoing international effort, coordinated by the International Bureau of Weights and Measures (BIPM) and the International Avogadro Coordination (IAC) to redefine the SI unit mole in terms of the Avogadro constant and the SI unit kg in terms of the Planck constant. One of the outgrowths of this effort has been the development of a novel, precise and highly accurate method to measure calibrated (absolute) isotopic ratios that are traceable to the SI (Vocke et al., 2014 Metrologia 51, 361, Azuma et al., 2015 Metrologia 52 360). This approach has also been able to produce absolute Si isotope ratio data with lower levels of uncertainty when compared to the traditional "Atomic Weights" method of absolute isotope ratio measurement. Silicon isotope variations (reported as delta(Si30)and delta(Si29)) in silicic acid dissolved in ocean waters, in biogenic silica and in diatoms are extremely informative paleo-nutrient proxies. The utility and comparability of such measurements however depends on calibration with artifact isotopic Reference Materials (iRMs). We will be reporting new measurements on the iRMs NBS-28 (RM 8546 - Silica Sand), Diatomite, Big Batch and SRM 990 using the Avogadro measurement approach, comparing them with prior assessments of these iRMs.

  7. Performance of Different Light Sources for the Absolute Calibration of Radiation Thermometers

    Science.gov (United States)

    Martín, M. J.; Mantilla, J. M.; del Campo, D.; Hernanz, M. L.; Pons, A.; Campos, J.

    2017-09-01

    The evolving mise en pratique for the definition of the kelvin (MeP-K) [1, 2] will, in its forthcoming edition, encourage the realization and dissemination of the thermodynamic temperature either directly (primary thermometry) or indirectly (relative primary thermometry) via fixed points with assigned reference thermodynamic temperatures. In the last years, the Centro Español de Metrología (CEM), in collaboration with the Instituto de Óptica of Consejo Superior de Investigaciones Científicas (IO-CSIC), has developed several setups for absolute calibration of standard radiation thermometers using the radiance method to allow CEM the direct dissemination of the thermodynamic temperature and the assignment of the thermodynamic temperatures to several fixed points. Different calibration facilities based on a monochromator and/or a laser and an integrating sphere have been developed to calibrate CEM's standard radiation thermometers (KE-LP2 and KE-LP4) and filter radiometer (FIRA2). This system is based on the one described in [3] placed in IO-CSIC. Different light sources have been tried and tested for measuring absolute spectral radiance responsivity: a Xe-Hg 500 W lamp, a supercontinuum laser NKT SuperK-EXR20 and a diode laser emitting at 6473 nm with a typical maximum power of 120 mW. Their advantages and disadvantages have been studied such as sensitivity to interferences generated by the laser inside the filter, flux stability generated by the radiant sources and so forth. This paper describes the setups used, the uncertainty budgets and the results obtained for the absolute temperatures of Cu, Co-C, Pt-C and Re-C fixed points, measured with the three thermometers with central wavelengths around 650 nm.

  8. Absolute in situ energy calibration of luminosity calorimeters in the DELPHI experiment at LEP

    International Nuclear Information System (INIS)

    Bugge, L.; Dam, M.; Read, A.L.; Myrheim, J.; Skjevling, G.

    1992-07-01

    Methods to perform the absolute energy calibration of DELPHI's Small Angle Tagger luminosity calorimeters at LEP are presented and compared. The input was small angle Bhabha scattering events. A significant non-linearity in the response of the calorimeters was observed. The conjugate gradient method was applied to solve the least square problem. This method is particularly useful for least squares problems which are large, ill-behaved or even singular, and for cases with a sparse coefficient matrix. 8 refs., 14 figs., 2 tabs

  9. Absolute frequencies of water lines near 790 nm with 10-11 accuracy

    Science.gov (United States)

    Chen, J.; Hua, T.-P.; Tao, L.-G.; Sun, Y. R.; Liu, A.-W.; Hu, S.-M.

    2018-01-01

    Water lines in the infrared are convenient frequency references. We present absolute positions of several H216O ro-vibrational transitions around 790 nm using comb-locked cavity ring-down saturation spectroscopy. Lamb dips of 6 water lines with saturation power in the range of 70-130 kW/cm2 were observed and the line positions were determined with an accuracy of 25 kHz, corresponding to a fractional uncertainty of 6.6 × 10-11. The present work demonstrates the capability to considerably improve the accuracy of the water line positions in the infrared.

  10. Calibration of ground-based microwave radiometers - Accuracy assessment and recommendations for network users

    Science.gov (United States)

    Pospichal, Bernhard; Küchler, Nils; Löhnert, Ulrich; Crewell, Susanne; Czekala, Harald; Güldner, Jürgen

    2016-04-01

    Ground-based microwave radiometers (MWR) are becoming widely used in atmospheric remote sensing and start to be routinely operated by national weather services and other institutions. However, common standards for calibration of these radiometers and a detailed knowledge about the error characteristics is needed, in order to assimilate the data into models. Intercomparisons of calibrations by different MWRs have rarely been done. Therefore, two calibration experiments in Lindenberg (2014) and Meckenheim (2015) were performed in the frame of TOPROF (Cost action ES1303) in order to assess uncertainties and differences between various instruments. In addition, a series of experiments were taken in Oklahoma in autumn 2014. The focus lay on the performance of the two main instrument types, which are currently used operationally. These are the MP-Profiler series by Radiometrics Corporation as well as the HATPRO series by Radiometer Physics GmbH (RPG). Both instrument types are operating in two frequency bands, one along the 22 GHz water vapour line, the other one at the lower wing of the 60 GHz oxygen absorption complex. The goal was to establish protocols for providing quality controlled (QC) MWR data and their uncertainties. To this end, standardized calibration procedures for MWR were developed and recommendations for radiometer users were compiled. We focus here mainly on data types, integration times and optimal settings for calibration intervals, both for absolute (liquid nitrogen, tipping curve) as well as relative (hot load, noise diode) calibrations. Besides the recommendations for ground-based MWR operators, we will present methods to determine the accuracy of the calibration as well as means for automatic data quality control. In addition, some results from the intercomparison of different radiometers will be discussed.

  11. Pantomime-grasping: Advance knowledge of haptic feedback availability supports an absolute visuo-haptic calibration

    Directory of Open Access Journals (Sweden)

    Shirin eDavarpanah Jazi

    2016-05-01

    Full Text Available An emerging issue in movement neurosciences is whether haptic feedback influences the nature of the information supporting a simulated grasping response (i.e., pantomime-grasping. In particular, recent work by our group contrasted pantomime-grasping responses performed with (i.e., PH+ trials and without (i.e., PH- trials terminal haptic feedback in separate blocks of trials. Results showed that PH- trials were mediated via relative visual information. In contrast, PH+ trials showed evidence of an absolute visuo-haptic calibration – a finding attributed to an error signal derived from a comparison between expected and actual haptic feedback (i.e., an internal forward model. The present study examined whether advanced knowledge of haptic feedback availability influences the aforementioned calibration process. To that end, PH- and PH+ trials were completed in separate blocks (i.e., the feedback schedule used in our group’s previous study and a block wherein PH- and PH+ trials were randomly interleaved on a trial-by-trial basis (i.e., random feedback schedule. In other words, the random feedback schedule precluded participants from predicting whether haptic feedback would be available at the movement goal location. We computed just-noticeable-difference (JND values to determine whether responses adhered to, or violated, the relative psychophysical principles of Weber’s law. Results for the blocked feedback schedule replicated our group’s previous work, whereas in the random feedback schedule PH- and PH+ trials were supported via relative visual information. Accordingly, we propose that a priori knowledge of haptic feedback is necessary to support an absolute visuo-haptic calibration. Moreover, our results demonstrate that the presence and expectancy of haptic feedback is an important consideration in contrasting the behavioral and neural properties of natural and stimulated (i.e., pantomime-grasping grasping.

  12. Absolute calibration of the Jenoptik CHM15k-x ceilometer and its applicability for quantitative aerosol monitoring

    Science.gov (United States)

    Geiß, Alexander; Wiegner, Matthias

    2014-05-01

    The knowledge of the spatiotemporal distribution of atmospheric aerosols and its optical characterization is essential for the understanding of the radiation budget, air quality, and climate. For this purpose, lidar is an excellent system as it is an active remote sensing technique. As multi-wavelength research lidars with depolarization channels are quite complex and cost-expensive, increasing attention is paid to so-called ceilometers. They are simple one-wavelength backscatter lidars with low pulse energy for eye-safe operation. As maintenance costs are low and continuous and unattended measurements can be performed, they are suitable for long-term aerosol monitoring in a network. However, the signal-to-noise ratio is low, and the signals are not calibrated. The only optical property that can be derived from a ceilometer is the particle backscatter coefficient, but even this quantity requires a calibration of the signals. With four years of measurements from a Jenoptik ceilometer CHM15k-x, we developed two methods for an absolute calibration on this system. This advantage of our approach is that only a few days with favorable meteorological conditions are required where Rayleigh-calibration and comparison with our research lidar is possible to estimate the lidar constant. This method enables us to derive the particle backscatter coefficient at 1064 nm, and we retrieved for the first time profiles in near real-time within an accuracy of 10 %. If an appropriate lidar ratio is assumed the aerosol optical depth of e.g. the mixing layer can be determined with an accuracy depending on the accuracy of the lidar ratio estimate. Even for 'simple' applications, e.g. assessment of the mixing layer height, cloud detection, detection of elevated aerosol layers, the particle backscatter coefficient has significant advantages over the measured (uncalibrated) attenuated backscatter. The possibility of continuous operation under nearly any meteorological condition with temporal

  13. Absolute-magnitude Calibration for W UMa-type Systems Based on Gaia Data

    Science.gov (United States)

    Mateo, Nicole M.; Rucinski, Slavek M.

    2017-09-01

    Tycho-Gaia Astrometric Solution (TGAS) parallax data are used to determine absolute magnitudes M V for 318 W UMa-type (EW) contact binary stars. A very steep (slope ≃ -9), single-parameter ({log}P), linear calibration can be used to predict M V to about 0.1-0.3 mag over the whole range of accessible orbital period, 0.22< P< 0.88 days. A similar calibration for the most common systems with 0.275< P< 0.575 days predicts M V values to about 0.06-0.16 mag. For orbital period values both shorter and longer than the central range, the period dependence is respectively steeper and shallower, I.e., the binaries are fainter in M V than predicted by the whole-range linear law. The steepness of the relation for short-period systems implies important consequences for the detectability of the faintest binaries, defining the short-period cut-off of the period distribution. Although the scatter around the linear {log}P-fit is fairly large (0.2-0.4 mag), the current data do not support the inclusion of a B-V color term in the calibration. ). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.

  14. Absolute calibration of the OMEGA streaked optical pyrometer for temperature measurements of compressed materials.

    Science.gov (United States)

    Gregor, M C; Boni, R; Sorce, A; Kendrick, J; McCoy, C A; Polsin, D N; Boehly, T R; Celliers, P M; Collins, G W; Fratanduono, D E; Eggert, J H; Millot, M

    2016-11-01

    Experiments in high-energy-density physics often use optical pyrometry to determine temperatures of dynamically compressed materials. In combination with simultaneous shock-velocity and optical-reflectivity measurements using velocity interferometry, these experiments provide accurate equation-of-state data at extreme pressures (P > 1 Mbar) and temperatures (T > 0.5 eV). This paper reports on the absolute calibration of the streaked optical pyrometer (SOP) at the Omega Laser Facility. The wavelength-dependent system response was determined by measuring the optical emission from a National Institute of Standards and Technology-traceable tungsten-filament lamp through various narrowband (40-nm-wide) filters. The integrated signal over the SOP's ∼250-nm operating range is then related to that of a blackbody radiator using the calibrated response. We present a simple closed-form equation for the brightness temperature as a function of streak-camera signal derived from this calibration. Error estimates indicate that brightness temperature can be inferred to a precision of <5%.

  15. Absolute calibration of the OMEGA streaked optical pyrometer for temperature measurements of compressed materials

    Science.gov (United States)

    Gregor, M. C.; Boni, R.; Sorce, A.; Kendrick, J.; McCoy, C. A.; Polsin, D. N.; Boehly, T. R.; Celliers, P. M.; Collins, G. W.; Fratanduono, D. E.; Eggert, J. H.; Millot, M.

    2016-11-01

    Experiments in high-energy-density physics often use optical pyrometry to determine temperatures of dynamically compressed materials. In combination with simultaneous shock-velocity and optical-reflectivity measurements using velocity interferometry, these experiments provide accurate equation-of-state data at extreme pressures (P > 1 Mbar) and temperatures (T > 0.5 eV). This paper reports on the absolute calibration of the streaked optical pyrometer (SOP) at the Omega Laser Facility. The wavelength-dependent system response was determined by measuring the optical emission from a National Institute of Standards and Technology-traceable tungsten-filament lamp through various narrowband (40-nm-wide) filters. The integrated signal over the SOP's ˜250-nm operating range is then related to that of a blackbody radiator using the calibrated response. We present a simple closed-form equation for the brightness temperature as a function of streak-camera signal derived from this calibration. Error estimates indicate that brightness temperature can be inferred to a precision of <5%.

  16. Accuracy of whole-body plethysmography requires biological calibration

    DEFF Research Database (Denmark)

    Poorisrisak, Porntiva; Vrang, Carsten; Henriksen, Jorn Molgaard

    2009-01-01

    of accuracy. Our aim was to determine the agreement of sRaw measurements in six centers and expand normative sRaw values for nonasthmatic children including these centers. METHOD: Identical hardware with different software versions was used at the six centers. Measurements followed a standard operating......BACKGROUND: Specific airway resistance (sRaw) measured by whole-body plethysmography in young children is increasingly used in research and clinical practice. The method is precise and feasible. However, there is no available method for calibration of the resistance measure, which raises concern...... procedure: (1) seven healthy young children were brought to each of the six centers for sRaw measurements; and (2) 105 healthy preschool children (52 boys; mean age, 5.1 years; interquartile range, 4.3 to 6.0) were recruited locally for sRaw measurements. RESULTS: (1) The sRaw of the seven-children study...

  17. Accuracy of whole-body plethysmography requires biological calibration.

    Science.gov (United States)

    Poorisrisak, Porntiva; Vrang, Carsten; Henriksen, Jorn Molgaard; Klug, Bent; Hanel, Birgitte; Bisgaard, Hans

    2009-06-01

    Specific airway resistance (sRaw) measured by whole-body plethysmography in young children is increasingly used in research and clinical practice. The method is precise and feasible. However, there is no available method for calibration of the resistance measure, which raises concern of accuracy. Our aim was to determine the agreement of sRaw measurements in six centers and expand normative sRaw values for nonasthmatic children including these centers. Identical hardware with different software versions was used at the six centers. Measurements followed a standard operating procedure: (1) seven healthy young children were brought to each of the six centers for sRaw measurements; and (2) 105 healthy preschool children (52 boys; mean age, 5.1 years; interquartile range, 4.3 to 6.0) were recruited locally for sRaw measurements. (1) The sRaw of the seven-children study group was significantly lower at two centers compared with the other four centers, and one center had significantly higher sRaw than all the other centers (p factory settings of the software was subsequently discovered in one of the deviating centers. (2) Normative data (105 preschool children) were generated and were without significant difference between centers and independent of height, weight, age, and gender. We subsequently pooled these normative data (105 children) with our previous data from 121 healthy young children (overall mean sRaw, 1.27; SD, 0.25). Control using biological standards revealed errors in the factory setting and highlights the need for developing methods for verification of resistance measures to assure accuracy. Normative data were subsequently generated. Importantly, other centers using such normative data should first consider proper calibration before applying reference values.

  18. Performance on absolute scattering intensity calibration and protein molecular weight determination at BL16B1, a dedicated SAXS beamline at SSRF.

    Science.gov (United States)

    Zeng, Jianrong; Bian, Fenggang; Wang, Jie; Li, Xiuhong; Wang, Yuzhu; Tian, Feng; Zhou, Ping

    2017-03-01

    The optical system and end-station of bending-magnet beamline BL16B1, dedicated to small-angle X-ray scattering (SAXS) at the Shanghai Synchrotron Radiation Facility, is described. Constructed in 2009 and upgraded in 2013, this beamline has been open to users since May 2009 and supports methodologies including SAXS, wide-angle X-ray scattering (WAXS), simultaneous SAXS/WAXS, grazing-incidence small-angle X-ray scattering (GISAXS) and anomalous small-angle X-ray scattering (ASAXS). Considering that an increasing necessity for absolute calibration of SAXS intensity has been recognized in in-depth investigations, SAXS intensity is re-stated according to the extent of data processing, and the absolute intensity is suggested to be a unified presentation of SAXS data in this article. Theory with a practical procedure for absolute intensity calibration is established based on BL16B1, using glass carbon and water as primary and secondary standards, respectively. The calibration procedure can be completed in minutes and shows good reliability under different conditions. An empirical line of scale factor estimation is also established for any specific SAXS setup at the beamline. Beamline performance on molecular weight (MW) determination is provided as a straightforward application and verification of the absolute intensity calibration. Results show good accuracy with a deviation of less than 10% compared with the known value, which is also the best attainable accuracy in recent studies using SAXS to measure protein MW. Fast MW measurement following the demonstrated method also enables an instant check or pre-diagnosis of the SAXS performance to improve the data acquisition.

  19. Absolute Density Calibration Cell for Laser Induced Fluorescence Erosion Rate Measurements

    Science.gov (United States)

    Domonkos, Matthew T.; Stevens, Richard E.

    2001-01-01

    Flight qualification of ion thrusters typically requires testing on the order of 10,000 hours. Extensive knowledge of wear mechanisms and rates is necessary to establish design confidence prior to long duration tests. Consequently, real-time erosion rate measurements offer the potential both to reduce development costs and to enhance knowledge of the dependency of component wear on operating conditions. Several previous studies have used laser-induced fluorescence (LIF) to measure real-time, in situ erosion rates of ion thruster accelerator grids. Those studies provided only relative measurements of the erosion rate. In the present investigation, a molybdenum tube was resistively heated such that the evaporation rate yielded densities within the tube on the order of those expected from accelerator grid erosion. This work examines the suitability of the density cell as an absolute calibration source for LIF measurements, and the intrinsic error was evaluated.

  20. Digital PCR provides sensitive and absolute calibration for high throughput sequencing

    Directory of Open Access Journals (Sweden)

    Fan H Christina

    2009-03-01

    Full Text Available Abstract Background Next-generation DNA sequencing on the 454, Solexa, and SOLiD platforms requires absolute calibration of the number of molecules to be sequenced. This requirement has two unfavorable consequences. First, large amounts of sample-typically micrograms-are needed for library preparation, thereby limiting the scope of samples which can be sequenced. For many applications, including metagenomics and the sequencing of ancient, forensic, and clinical samples, the quantity of input DNA can be critically limiting. Second, each library requires a titration sequencing run, thereby increasing the cost and lowering the throughput of sequencing. Results We demonstrate the use of digital PCR to accurately quantify 454 and Solexa sequencing libraries, enabling the preparation of sequencing libraries from nanogram quantities of input material while eliminating costly and time-consuming titration runs of the sequencer. We successfully sequenced low-nanogram scale bacterial and mammalian DNA samples on the 454 FLX and Solexa DNA sequencing platforms. This study is the first to definitively demonstrate the successful sequencing of picogram quantities of input DNA on the 454 platform, reducing the sample requirement more than 1000-fold without pre-amplification and the associated bias and reduction in library depth. Conclusion The digital PCR assay allows absolute quantification of sequencing libraries, eliminates uncertainties associated with the construction and application of standard curves to PCR-based quantification, and with a coefficient of variation close to 10%, is sufficiently precise to enable direct sequencing without titration runs.

  1. Effects of lens distortion calibration patterns on the accuracy of monocular 3D measurements

    CSIR Research Space (South Africa)

    De Villiers, J

    2011-11-01

    Full Text Available unified and objective manner. A common image dataset is captured along with physical measurements and is used to quantify the photogrammetric accuracy of the different calibration techniques. Multiple calibration patterns and sizes are tested and compared...

  2. Calibrated fMRI for mapping absolute CMRO2: Practicalities and prospects.

    Science.gov (United States)

    Germuska, M; Wise, R G

    2018-03-29

    Functional magnetic resonance imaging (fMRI) is an essential workhorse of modern neuroscience, providing valuable insight into the functional organisation of the brain. The physiological mechanisms underlying the blood oxygenation level dependent (BOLD) effect are complex and preclude a straightforward interpretation of the signal. However, by employing appropriate calibration of the BOLD signal, quantitative measurements can be made of important physiological parameters including the absolute rate of cerebral metabolic oxygen consumption or oxygen metabolism (CMRO 2 ) and oxygen extraction (OEF). The ability to map such fundamental parameters has the potential to greatly expand the utility of fMRI and to broaden its scope of application in clinical research and clinical practice. In this review article we discuss some of the practical issues related to the calibrated-fMRI approach to the measurement of CMRO 2 . We give an overview of the necessary precautions to ensure high quality data acquisition, and explore some of the pitfalls and challenges that must be considered as it is applied and interpreted in a widening array of diseases and research questions. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. 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.

  4. Study on the performances of an absolute atomic gravimeter: limit sensitivity and preliminary accuracy

    International Nuclear Information System (INIS)

    Le Gouet, J.

    2008-02-01

    Atom interferometry is applied to absolute measurement of gravity acceleration g, to provide an accurate value for the realization of the LNE watt balance. The atomic source is obtained from a cloud of cold 87 Rubidium atoms. Two vertical counter-propagating are used to generate stimulated Raman transitions, that separate the wave-packets and make them interfere. During the transitions, the phase difference between the beams is printed on the phase of the free-falling atoms. Then the atomic phase shift between the two vertical paths becomes sensitive to the atom acceleration and allows obtaining an accurate value of g. A part of this manuscript is dedicated to the study of noise sources which deteriorate the measurement sensitivity. In particular, we detail the vibrations contribution, which we are able to reduce by a factor of 3 to 10, depending on the configurations, thanks to the measurement of a seismometer and to its analog processing. The best reported sensitivity, in optimal environment, is 1.4*10 -8 g/Hz 1/2 . The study of the measurement accuracy also represents an important part of this work. Although the vacuum chamber was only temporary, we started to list the systematic shifts. According to two comparisons with well-known absolute gravimeters based on optical interferometry, our measurement shows a residual bias of 16*10 -9 g. (author)

  5. Improved accuracy for label-free absolute quantification of proteome by combining the Absolute Protein EXpression profiling algorithm and summed tandem mass spectrometric total ion current.

    Science.gov (United States)

    Wu, Qi; Shan, Yichu; Qu, Yanyan; Jiang, Hao; Yuan, Huiming; Liu, Jianxi; Zhang, Shen; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

    2014-01-07

    Proteome scale absolute quantification is fundamental for the quantitative understanding of an organism. The unsatisfactory accuracy for protein abundance estimation of current algorithms has been partially improved by the Absolute Protein EXpression profiling (APEX) algorithm, which implements the prior expectations of peptides' appearances in the calculation of protein abundances. However, the abundance feature (AF) in APEX is the spectral count (SC); an AF suffers from a narrow dynamic range, thus, unsatisfactory accuracy. Therefore, we adopted another tandem mass spectrometric (MS/MS) level AF called Summed MS/MS Total ion current (SMT), which cumulates the MS/MS fragment intensities rather than simply counting the MS/MS spectra, to surmount this particular deficiency. The combination of APEX and SMT (abbreviated as APEX-SMT) is capable of improving the accuracy of absolute quantification by reducing the average relative deviation by ~55-85% compared to that of APEX, through a series of tests on the Universal Proteomics Standard sample with a dynamic range of 5 orders of magnitude (UPS2). The algorithm could also be used for relative quantification. When applied to the relative quantification of a publicly available benchmark dataset, APEX-SMT could provide comparable accuracy to APEX. All these results suggest that APEX-SMT is a promising alternative to APEX for proteome quantification.

  6. Achieving High Absolute Accuracy for Group-Delay Measurements Using the Modulation Phase-Shift Technique

    Science.gov (United States)

    Dennis, T.; Williams, P. A.

    2005-11-01

    We have developed a modulation phase-shift (MPS) system for measuring relative group delay (RGD) in optical components with high absolute accuracy and simultaneously high temporal and wavelength resolution. Our 200-MHz system has a 3.2-pm wavelength resolution and has demonstrated a group-delay resolution of 0.072 ps for repeated measurements of an artifact based on a hydrogen-cyanide gas cell. The expanded uncertainty (2sigma) is +/-0.46 ps for a single spectral measurement (~ 3.4-pm steps) of a narrow 20-ps group-delay feature of the artifact. To our knowledge, this is the first time that the sources of measurement uncertainty for this technique have been described and quantified. A method for predicting the group delay of the gas-cell artifact from measured absorption spectra is described, and an uncertainty analysis for the prediction method is also presented. The implementation required to achieve results of the highest accuracy for both measurements and predictions is discussed.

  7. From direct to absolute mass measurements a study of the accuracy of ISOLTRAP

    CERN Document Server

    Kellerbauer, A G; Bollen, G; Herfurth, F; Kluge, H J; Kuckein, M; Sauvan, E; Scheidenberger, C; Schweikhard, L

    2003-01-01

    For a detailed study of the accuracy of the Penning trap mass spectrometer ISOLTRAP all expected sources of uncertainty were investigated with respect to their contributions to the uncertainty of the final result. In the course of these investigations, cross-reference measurements with singly charged carbon clusters $^{12}$C$^{+}_{n}$ were carried out. The carbon cluster ions were produced by use of laser-induced desorption, fragmentation, and ionization of C$_{60}$ fullerenes and injected into and stored in the Penning trap system. The comparison of the cyclotron frequencies of different carbon clusters has provided detailed insight into the residual systematic uncertainty of \\acro{ISOLTRAP} and yielded a value of $8 \\cdot 10^{-9}$. This also represents the current limit of mass accuracy of the apparatus. Since the unified atomic mass unit is defined as 1/12 of the mass of the $^{12}$C atom, it will be possible to carry out absolute mass measurements with \\acro{ISOLTRAP} in the future.\\\\[1\\baselineskip] PACS...

  8. Improved Strategies and Optimization of Calibration Models for Real-time PCR Absolute Quantification

    Science.gov (United States)

    Real-time PCR absolute quantification applications rely on the use of standard curves to make estimates of DNA target concentrations in unknown samples. Traditional absolute quantification approaches dictate that a standard curve must accompany each experimental run. However, t...

  9. An Absolute Self-Calibrating Pressure Recorder for Campaign-Style Detection of Vertical Seafloor Deformation in the Cascadia Subduction Zone

    Science.gov (United States)

    Cook, M. J.; Roland, E. C.; Sasagawa, G. S.; Schmidt, D. A.; Wilcock, W. S. D.; Zumberge, M. A.

    2016-12-01

    Seawater pressure can be used to detect vertical seafloor deformation because small changes in seafloor height produce measurable pressure changes. Vertical deformation rates in subduction zones due to secular strain are expected to be less than 1 cm/year, signals that are difficult to measure with pressure gauges because of gauge drift. The Self-Calibrating Pressure Recorder (SCPR) was designed to circumvent the problem of gauge drift by employing a deadweight calibrator, which periodically provides a reference pressure that is used to correct for drift in a continuously recorded pressure record. Alternatively, the SCPR can be used to make campaign-style determinations of true seafloor pressure to support long-term deformation measurements and provide an exact reference for nearby pressure gauges. This Absolute Self-Calibrating Pressure Recorder (ASCPR) requires a metrological assessment of measurement parameters to ensure that its absolute accuracy is sufficient to resolve secular deformation. While on a concrete seafloor benchmark, alternating calibration and seawater observations are made every 10-20 minutes for several hours. The difference between the known reference pressure and the seafloor pressure is observed, which allows the calculation of the true, absolute seafloor pressure. In 2014 and 2015, seven concrete benchmarks were placed on the seafloor in the Cascadia subduction zone off central Oregon along a profile that extends from 20 km to 105 km offshore. We surveyed two benchmarks in 2014, 2015, and 2016, a third one in 2015 and 2016, and four more in 2016. Current measurement repeatability varies from 2 to 5 cm, but several corrections still need to be incorporated. The expected resolution is 1 cm.

  10. Water Vapor Products from Differential-InSAR with Auxiliary Calibration Data: Accuracy and Statistics

    Science.gov (United States)

    Gong, W.; Meyer, F. J.; Webley, P.

    2014-12-01

    calibration data set and their corresponding accuracy; and (3) Accuracy of the derived absolute water vapor products. Overall, we work on the strategy definition that bring the d-InSAR-derived water vapor products to be practically generated association with their accuracy information and available to wide research communities.

  11. Absolute calibration of space- and time-resolving flat-field vacuum ultraviolet spectrograph for plasma diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Yuuji; Yoshikawa, Masayuki; Watabe, Chikara; Tamano, Teruo; Kawamori, Eiichirou; Ito, Takahiro; Watanabe, Yoshihiko; Yatsu, Kiyoshi [Plasma Research Center, Tsukuba Univ., Ibaraki (Japan); Yamaguchi, Naohiro [Toyota Technological Inst., Nagoya (Japan)

    2000-06-01

    Measurement of spectra in the wavelength range from vacuum ultraviolet (VUV) to soft X-ray is an important means to diagnose impurities in magnetically confined plasmas used in fusion plasmas such as a GAMMA10 plasma. Recently, a space- and time-resolving flat-field grazing-incidence VUV spectrograph was constructed for the simultaneous observation of spatial, temporal and spectral distributions of plasma radiation in the wavelength range of 150-1050 A. Absolute calibration experiments were performed at beamline 11C in the Photon Factory at the High Energy Accelerator Research Organization. The absolute efficiency of the VUV spectrograph was measured for P polarization geometry in the spectrograph. (author)

  12. Absolute calibration of space- and time-resolving flat-field vacuum ultraviolet spectrograph for plasma diagnostics

    International Nuclear Information System (INIS)

    Okamoto, Yuuji; Yoshikawa, Masayuki; Watabe, Chikara; Tamano, Teruo; Kawamori, Eiichirou; Ito, Takahiro; Watanabe, Yoshihiko; Yatsu, Kiyoshi; Yamaguchi, Naohiro

    2000-01-01

    Measurement of spectra in the wavelength range from vacuum ultraviolet (VUV) to soft X-ray is an important means to diagnose impurities in magnetically confined plasmas used in fusion plasmas such as a GAMMA10 plasma. Recently, a space- and time-resolving flat-field grazing-incidence VUV spectrograph was constructed for the simultaneous observation of spatial, temporal and spectral distributions of plasma radiation in the wavelength range of 150-1050 A. Absolute calibration experiments were performed at beamline 11C in the Photon Factory at the High Energy Accelerator Research Organization. The absolute efficiency of the VUV spectrograph was measured for P polarization geometry in the spectrograph. (author)

  13. Exploring a Black Body Source as an Absolute Radiometric Calibration Standard and Comparison with a NIST Traced Lamp Standard

    Science.gov (United States)

    Green, Robert O.; Chrien, Thomas; Sarture, Chuck

    2001-01-01

    Radiometric calibration of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) is required for the scientific research and application objectives pursued with the spectroscopic measurements. Specifically calibration is required for: inter-comparison of AVIRIS data measured at different locations and at different times; analysis of AVIRIS data with data measured by other instruments; and analysis of AVIRIS data in conjunction with computer models. The primary effect of radiometric calibration is conversion of AVIRIS instrument response values (digitized numbers, or DN) to units of absolute radiance. For example, a figure shows the instrument response spectrum measured by AVIRIS over a portion of Rogers Dry Lake, California, and another figure shows the same spectrum calibrated to radiance. Only the calibrated spectrum may be quantitatively analyzed for science research and application objectives. Since the initial development of the AVIRIS instrument-radiometric calibration has been based upon a 1000-W irradiance lamp with a calibration traced to the National Institute of Standards and Technology (NIST). There are several advantages to this irradiance-lamp calibration approach. First, the considerable effort of NIST backs up the calibration. Second, by changing the distance to the lamp, the output can closely span the radiance levels measured by AVIRIS. Third, this type of standard is widely used. Fourth, these calibrated lamps are comparatively inexpensive. Conversely, there are several disadvantages to this approach as well. First, the lamp is not a primary standard. Second, the lamp output characteristics may change in an unknown manner through time. Third, it is difficult to assess, constrain, or improve the calibration uncertainty delivered with the lamp. In an attempt to explore the effect and potentially address some of these disadvantages a set of analyses and measurements comparing an irradiance lamp with a black-body source have been completed

  14. Absolute distance measurement with micrometer accuracy using a Michelson interferometer and the iterative synthetic wavelength principle.

    Science.gov (United States)

    Alzahrani, Khaled; Burton, David; Lilley, Francis; Gdeisat, Munther; Bezombes, Frederic; Qudeisat, Mohammad

    2012-02-27

    We present a novel system that can measure absolute distances of up to 300 mm with an uncertainty of the order of one micrometer, within a timeframe of 40 seconds. The proposed system uses a Michelson interferometer, a tunable laser, a wavelength meter and a computer for analysis. The principle of synthetic wave creation is used in a novel way in that the system employs an initial low precision estimate of the distance, obtained using a triangulation, or time-of-flight, laser system, or similar, and then iterates through a sequence of progressively smaller synthetic wavelengths until it reaches micrometer uncertainties in the determination of the distance. A further novel feature of the system is its use of Fourier transform phase analysis techniques to achieve sub-wavelength accuracy. This method has the major advantages of being relatively simple to realize, offering demonstrated high relative precisions better than 5 × 10(-5). Finally, the fact that this device does not require a continuous line-of-sight to the target as is the case with other configurations offers significant advantages.

  15. Prototype of Cryogenic Solar Absolute Radiometer and Transfer Radiometer for On-Board Calibration of Spectral Earth Imager

    Science.gov (United States)

    Zajiczek, L.; Winkler, R.; Hobson, T.; Green, P.; Fox, N.

    2018-02-01

    We describe a prototype calibration system for the Traceable Radiometry Underpinning Terrestrial- and Helio-Studies (TRUTHS) satellite mission. We outline the design and testing of key system components, including the Cryogenic Solar Absolute Radiometer (CSAR). CSAR is designed to make Total Solar Irradiance (TSI) measurements with a standard uncertainty of < 0.01 % and provide SI-traceable calibration of a hyperspectral Earth imager (EI) over the wavelength range 320 nm – 2450 nm. The EI is designed to make Solar Spectral Irradiance (SSI) and spectral radiance measurements with a standard uncertainty of < 0.3 %.

  16. Real-time continuous glucose monitoring shows high accuracy within 6 hours after sensor calibration: a prospective study.

    Directory of Open Access Journals (Sweden)

    Xiao-Yan Yue

    Full Text Available Accurate and timely glucose monitoring is essential in intensive care units. Real-time continuous glucose monitoring system (CGMS has been advocated for many years to improve glycemic management in critically ill patients. In order to determine the effect of calibration time on the accuracy of CGMS, real-time subcutaneous CGMS was used in 18 critically ill patients. CGMS sensor was calibrated with blood glucose measurements by blood gas/glucose analyzer every 12 hours. Venous blood was sampled every 2 to 4 hours, and glucose concentration was measured by standard central laboratory device (CLD and by blood gas/glucose analyzer. With CLD measurement as reference, relative absolute difference (mean±SD in CGMS and blood gas/glucose analyzer were 14.4%±12.2% and 6.5%±6.2%, respectively. The percentage of matched points in Clarke error grid zone A was 74.8% in CGMS, and 98.4% in blood gas/glucose analyzer. The relative absolute difference of CGMS obtained within 6 hours after sensor calibration (8.8%±7.2% was significantly less than that between 6 to 12 hours after calibration (20.1%±13.5%, p<0.0001. The percentage of matched points in Clarke error grid zone A was also significantly higher in data sets within 6 hours after calibration (92.4% versus 57.1%, p<0.0001. In conclusion, real-time subcutaneous CGMS is accurate in glucose monitoring in critically ill patients. CGMS sensor should be calibrated less than 6 hours, no matter what time interval recommended by manufacturer.

  17. Absolute Calibration of Image Plate for electrons at energy between 100 keV and 4 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H; Back, N L; Eder, D C; Ping, Y; Song, P M; Throop, A

    2007-12-10

    The authors measured the absolute response of image plate (Fuji BAS SR2040) for electrons at energies between 100 keV to 4 MeV using an electron spectrometer. The electron source was produced from a short pulse laser irradiated on the solid density targets. This paper presents the calibration results of image plate Photon Stimulated Luminescence PSL per electrons at this energy range. The Monte Carlo radiation transport code MCNPX results are also presented for three representative incident angles onto the image plates and corresponding electron energies depositions at these angles. These provide a complete set of tools that allows extraction of the absolute calibration to other spectrometer setting at this electron energy range.

  18. Determining the importance of model calibration for forecasting absolute/relative changes in streamflow from LULC and climate changes

    Science.gov (United States)

    Niraula, Rewati; Meixner, Thomas; Norman, Laura M.

    2015-01-01

    Land use/land cover (LULC) and climate changes are important drivers of change in streamflow. Assessing the impact of LULC and climate changes on streamflow is typically done with a calibrated and validated watershed model. However, there is a debate on the degree of calibration required. The objective of this study was to quantify the variation in estimated relative and absolute changes in streamflow associated with LULC and climate changes with different calibration approaches. The Soil and Water Assessment Tool (SWAT) was applied in an uncalibrated (UC), single outlet calibrated (OC), and spatially-calibrated (SC) mode to compare the relative and absolute changes in streamflow at 14 gaging stations within the Santa Cruz River Watershed in southern Arizona, USA. For this purpose, the effect of 3 LULC, 3 precipitation (P), and 3 temperature (T) scenarios were tested individually. For the validation period, Percent Bias (PBIAS) values were >100% with the UC model for all gages, the values were between 0% and 100% with the OC model and within 20% with the SC model. Changes in streamflow predicted with the UC and OC models were compared with those of the SC model. This approach implicitly assumes that the SC model is “ideal”. Results indicated that the magnitude of both absolute and relative changes in streamflow due to LULC predicted with the UC and OC results were different than those of the SC model. The magnitude of absolute changes predicted with the UC and SC models due to climate change (both P and T) were also significantly different, but were not different for OC and SC models. Results clearly indicated that relative changes due to climate change predicted with the UC and OC were not significantly different than that predicted with the SC models. This result suggests that it is important to calibrate the model spatially to analyze the effect of LULC change but not as important for analyzing the relative change in streamflow due to climate change. This

  19. Improvement of Accuracy in Environmental Dosimetry by TLD Cards Using Three-dimensional Calibration Method

    Directory of Open Access Journals (Sweden)

    HosseiniAliabadi S. J.

    2015-06-01

    Full Text Available Background: The angular dependency of response for TLD cards may cause deviation from its true value on the results of environmental dosimetry, since TLDs may be exposed to radiation at different angles of incidence from the surrounding area. Objective: A 3D setting of TLD cards has been calibrated isotropically in a standard radiation field to evaluate the improvement of the accuracy of measurement for environmental dosimetry. Method: Three personal TLD cards were rectangularly placed in a cylindrical holder, and calibrated using 1D and 3D calibration methods. Then, the dosimeter has been used simultaneously with a reference instrument in a real radiation field measuring the accumulated dose within a time interval. Result: The results show that the accuracy of measurement has been improved by 6.5% using 3D calibration factor in comparison with that of normal 1D calibration method. Conclusion: This system can be utilized in large scale environmental monitoring with a higher accuracy

  20. Comparison of the accuracy of the calibration model on the double and single integrating sphere systems

    CSIR Research Space (South Africa)

    Singh

    2011-05-01

    Full Text Available The accuracy of the calibration model for the single and double integrating sphere systems are compared for a white light system. A calibration model is created from a matrix of samples with known absorption and reduced scattering coefficients...

  1. Calibration of 'gammascan' for stability, reliability and accuracy of measurements

    International Nuclear Information System (INIS)

    Walinjkar, P.B.; Umesh Kumar; Pendharkar, A.S.; Singh, Gursharan

    2003-01-01

    Full text: For any type of radiation measurements, the instrument must be stable and reliable under the environmental conditions. The stability, reliability and accuracy of measurements are the parameters that affect the performance of any system. In this paper the results of the measurements carried out to test the performance of 'Gammascan' a microprocessor based gamma counter-data acquisition unit are presented. The operation of unit was optimized using a 137 Cs (0.1 mCi, 662 keV) disc source. The accuracy of unit was measured by calculating a standard deviation of the readings. The readings of 10 sec each recorded continuously for six hrs to see the long-term stability of the unit. For repeatability /reproducibility with the same physical conditions the measurements were repeated over an interval of few days. The results of the tests were carried out in the lab are encouraging and satisfactory

  2. Knowing right from wrong in mental arithmetic judgments: calibration of confidence predicts the development of accuracy.

    Science.gov (United States)

    Rinne, Luke F; Mazzocco, Michèle M M

    2014-01-01

    Does knowing when mental arithmetic judgments are right--and when they are wrong--lead to more accurate judgments over time? We hypothesize that the successful detection of errors (and avoidance of false alarms) may contribute to the development of mental arithmetic performance. Insight into error detection abilities can be gained by examining the "calibration" of mental arithmetic judgments-that is, the alignment between confidence in judgments and the accuracy of those judgments. Calibration may be viewed as a measure of metacognitive monitoring ability. We conducted a developmental longitudinal investigation of the relationship between the calibration of children's mental arithmetic judgments and their performance on a mental arithmetic task. Annually between Grades 5 and 8, children completed a problem verification task in which they rapidly judged the accuracy of arithmetic expressions (e.g., 25 + 50 = 75) and rated their confidence in each judgment. Results showed that calibration was strongly related to concurrent mental arithmetic performance, that calibration continued to develop even as mental arithmetic accuracy approached ceiling, that poor calibration distinguished children with mathematics learning disability from both low and typically achieving children, and that better calibration in Grade 5 predicted larger gains in mental arithmetic accuracy between Grades 5 and 8. We propose that good calibration supports the implementation of cognitive control, leading to long-term improvement in mental arithmetic accuracy. Because mental arithmetic "fluency" is critical for higher-level mathematics competence, calibration of confidence in mental arithmetic judgments may represent a novel and important developmental predictor of future mathematics performance.

  3. Knowing right from wrong in mental arithmetic judgments: calibration of confidence predicts the development of accuracy.

    Directory of Open Access Journals (Sweden)

    Luke F Rinne

    Full Text Available Does knowing when mental arithmetic judgments are right--and when they are wrong--lead to more accurate judgments over time? We hypothesize that the successful detection of errors (and avoidance of false alarms may contribute to the development of mental arithmetic performance. Insight into error detection abilities can be gained by examining the "calibration" of mental arithmetic judgments-that is, the alignment between confidence in judgments and the accuracy of those judgments. Calibration may be viewed as a measure of metacognitive monitoring ability. We conducted a developmental longitudinal investigation of the relationship between the calibration of children's mental arithmetic judgments and their performance on a mental arithmetic task. Annually between Grades 5 and 8, children completed a problem verification task in which they rapidly judged the accuracy of arithmetic expressions (e.g., 25 + 50 = 75 and rated their confidence in each judgment. Results showed that calibration was strongly related to concurrent mental arithmetic performance, that calibration continued to develop even as mental arithmetic accuracy approached ceiling, that poor calibration distinguished children with mathematics learning disability from both low and typically achieving children, and that better calibration in Grade 5 predicted larger gains in mental arithmetic accuracy between Grades 5 and 8. We propose that good calibration supports the implementation of cognitive control, leading to long-term improvement in mental arithmetic accuracy. Because mental arithmetic "fluency" is critical for higher-level mathematics competence, calibration of confidence in mental arithmetic judgments may represent a novel and important developmental predictor of future mathematics performance.

  4. The Pierre Auger fluorescence detector. Cross-checking the absolute calibration using a drone

    Energy Technology Data Exchange (ETDEWEB)

    Tomankova, Lenka [Institute for Nuclear Physics (IKP), Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe (Germany); Collaboration: Pierre-Auger-Collaboration

    2016-07-01

    The Pierre Auger Observatory combines the air shower fluorescence and surface array methods to study ultra-high energy cosmic rays. As the energy scale of the experiment is derived from calorimetric measurements by the fluorescence telescopes, their accurate calibration is of primary importance to all Auger data. We discuss a novel calibration method based on a remotely flown drone equipped with a specially designed light source that mimics a snapshot of an air shower traversing the atmosphere. Several drone measurement campaigns have been performed to study the properties of the Auger fluorescence telescopes and to derive an end-to-end calibration. We give an overview of the measurements and present the basic analysis chain as well as the first results of an independent cross-check of the Auger energy scale.

  5. Absolute calibration of Phase Contrast Imaging on HL-2A tokamak

    Science.gov (United States)

    Yu, Yi; Gong, Shaobo; Xu, Min; Wu, Yifan; Yuan, Boda; Ye, Minyou; Duan, Xuru; HL-2A team Team

    2017-10-01

    Phase contrast imaging (PCI) has recently been developed on HL-2A tokamak. In this article we present the calibration of this diagnostic. This system is to diagnose chord integral density fluctuations by measuring the phase shift of a CO2 laser beam with a wavelength of 10.6 μm when the laser beam passes through plasma. Sound waves are used to calibrate PCI diagnostic. The signal series in different PCI channels show a pronounced modulation of incident laser beam by the sound wave. Frequency-wavenumber spectrum is achieved. Calibrations by sound waves with different frequencies exhibit a maximal wavenumber response of 12 cm-1. The conversion relationship between the chord integral plasma density fluctuation and the signal intensity is 2.3-1013 m-2/mV, indicating a high sensitivity. Supported by the National Magnetic Confinement Fusion Energy Research Project (Grant No.2015GB120002, 2013GB107001).

  6. Piston manometer as an absolute standard for vacuum-gauge calibration.

    Science.gov (United States)

    Warshawsky, I.

    1972-01-01

    Determination of the total pressure in a calibration volume by measuring the force on a thin circular disk, of accurately known area, that is freely suspended in a hole in the container wall, so that the disk is substantially flush with the wall. The disk almost fills the hole, so that there is a narrow annular gap. A continuous flow of calibrating gas, injected into the container in order to maintain a desired pressure, passes through the annular gap to a diffusion pump. The ratio of pressures on the two faces of the disk is of the order of 100:1, so that downstream pressure need be known only nominally in order to deduce the upstream surface. Force on the disk is measured by a balance that is calibrated in situ with dead weights. In one arrangement, pressures in the range from 10 to 500 microtorr were measured with an estimated probable error of (1 microtorr + 1%).

  7. Absolute spectral calibration of an intensified CCD camera using twin beams

    Czech Academy of Sciences Publication Activity Database

    Haderka, O.; Peřina Jr., J.; Michálek, Václav; Hamar, Martin

    2014-01-01

    Roč. 31, č. 10 (2014), B1-B7 ISSN 0740-3224 R&D Projects: GA ČR GAP205/12/0382 Institutional support: RVO:68378271 Keywords : spectral calibration * intensified CCD camera * twin beams * photon pairs Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.970, year: 2014

  8. Absolute near-infrared refractometry with a calibrated tilted fiber Bragg grating.

    Science.gov (United States)

    Zhou, Wenjun; Mandia, David J; Barry, Seán T; Albert, Jacques

    2015-04-15

    The absolute refractive indices (RIs) of water and other liquids are determined with an uncertainty of ±0.001 at near-infrared wavelengths by using the tilted fiber Bragg grating (TFBG) cladding mode resonances of a standard single-mode fiber to measure the critical angle for total internal reflection at the interface between the fiber and its surroundings. The necessary condition to obtain absolute RIs (instead of measuring RI changes) is a thorough characterization of the dispersion of the core mode effective index of the TFBG across the full range of its cladding mode resonance spectrum. This technique is shown to be competitive with the best available measurements of the RIs of water and NaCl solutions at wavelengths in the vicinity of 1550 nm.

  9. Optical System Error Analysis and Calibration Method of High-Accuracy Star Trackers

    Directory of Open Access Journals (Sweden)

    Zheng You

    2013-04-01

    Full Text Available The star tracker is a high-accuracy attitude measurement device widely used in spacecraft. Its performance depends largely on the precision of the optical system parameters. Therefore, the analysis of the optical system parameter errors and a precise calibration model are crucial to the accuracy of the star tracker. Research in this field is relatively lacking a systematic and universal analysis up to now. This paper proposes in detail an approach for the synthetic error analysis of the star tracker, without the complicated theoretical derivation. This approach can determine the error propagation relationship of the star tracker, and can build intuitively and systematically an error model. The analysis results can be used as a foundation and a guide for the optical design, calibration, and compensation of the star tracker. A calibration experiment is designed and conducted. Excellent calibration results are achieved based on the calibration model. To summarize, the error analysis approach and the calibration method are proved to be adequate and precise, and could provide an important guarantee for the design, manufacture, and measurement of high-accuracy star trackers.

  10. Optical system error analysis and calibration method of high-accuracy star trackers.

    Science.gov (United States)

    Sun, Ting; Xing, Fei; You, Zheng

    2013-04-08

    The star tracker is a high-accuracy attitude measurement device widely used in spacecraft. Its performance depends largely on the precision of the optical system parameters. Therefore, the analysis of the optical system parameter errors and a precise calibration model are crucial to the accuracy of the star tracker. Research in this field is relatively lacking a systematic and universal analysis up to now. This paper proposes in detail an approach for the synthetic error analysis of the star tracker, without the complicated theoretical derivation. This approach can determine the error propagation relationship of the star tracker, and can build intuitively and systematically an error model. The analysis results can be used as a foundation and a guide for the optical design, calibration, and compensation of the star tracker. A calibration experiment is designed and conducted. Excellent calibration results are achieved based on the calibration model. To summarize, the error analysis approach and the calibration method are proved to be adequate and precise, and could provide an important guarantee for the design, manufacture, and measurement of high-accuracy star trackers.

  11. Absolute calibration method for fast-streaked, fiber optic light collection, spectroscopy systems

    International Nuclear Information System (INIS)

    Johnston, Mark D.; Frogget, Brent; Oliver, Bryan Velten; Maron, Yitzhak; Droemer, Darryl W.; Crain, Marlon D.

    2010-01-01

    This report outlines a convenient method to calibrate fast (<1ns resolution) streaked, fiber optic light collection, spectroscopy systems. Such a system is used to collect spectral data on plasmas generated in the A-K gap of electron beam diodes fielded on the RITS-6 accelerator (8-12MV, 140-200kA). On RITS, light is collected through a small diameter (200 micron) optical fiber and recorded on a fast streak camera at the output of 1 meter Czerny-Turner monochromator (F/7 optics). To calibrate such a system, it is necessary to efficiently couple light from a spectral lamp into a 200 micron diameter fiber, split it into its spectral components, with 10 Angstroms or less resolution, and record it on a streak camera with 1ns or less temporal resolution.

  12. A simple method for bracketing absolute divergence times on molecular phylogenies using multiple fossil calibration points.

    Science.gov (United States)

    Marshall, Charles R

    2008-06-01

    A central challenge facing the temporal calibration of molecular phylogenies is finding a quantitative method for estimating maximum age constraints on lineage divergence times. Here, I provide such a method. This method requires an ultrametric tree generated without reference to the fossil record. Exploiting the fact that the relative branch lengths on the ultrametric tree are proportional to time, this method identifies the lineage with the greatest proportion of its true temporal range covered by the fossil record. The oldest fossil of this calibration lineage is used as the minimum age constraint. The maximum age constraint is obtained by adding a confidence interval onto the end point of the calibration lineage, thus making it possible to bracket the true divergence times of all lineages on the tree. The approach can also identify fossils that have been grossly misdated or misassigned to the phylogeny. The method assumes that the relative branch lengths on the ultrametric tree are accurate and that fossilization is random. The effect of violations of these assumptions is assessed. This method is simple to use and is illustrated with a reanalysis of Near et al.'s turtle data.

  13. Very high-accuracy calibration of radiation pattern and gain of a near-field probe

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Nielsen, Jeppe Majlund; Breinbjerg, Olav

    2014-01-01

    In this paper, very high-accuracy calibration of the radiation pattern and gain of a near-field probe is described. An open-ended waveguide near-field probe has been used in a recent measurement of the C-band Synthetic Aperture Radar (SAR) Antenna Subsystem for the Sentinel 1 mission of the Europ......In this paper, very high-accuracy calibration of the radiation pattern and gain of a near-field probe is described. An open-ended waveguide near-field probe has been used in a recent measurement of the C-band Synthetic Aperture Radar (SAR) Antenna Subsystem for the Sentinel 1 mission...

  14. Absolute calibration of a cold and thermal neutron detector using monochromatic neutron beam

    Science.gov (United States)

    Choi, Jin Ha; Cude-Woods, Christopher; Ito, Takeyasu; Young, Albert

    2017-09-01

    Time of flight spectra for cold neutrons exiting the moderator volume of the LANSCE UCN source has been obtained using a commercial neutron scintillator, EJ-426, coupled to a Hamamatsu R1355. The absolute efficiency for this detector system was determined using a 37.4 meV (monochromatic) neutron beam from the Neutron Powder Diffraction Facility (NPDF) at North Carolina State University's PULSTAR reactor. We measured the absolute neutron flux at the NPDF through thin foil activation and explored threshold effects through analysis of the measured pulse height distribution for effectively pure neutron signals from the NPDF beam. Non-uniformity of the flux profile across the detector and the detection efficiency as a function of the point of incidence of neutrons on the scintillator was explored using a X-Y translation system to perform scans using either fixed or movable apertures. The results are generally consistent with our expectations for this system, and provide a quantitative assessment of the sensitivity of this system to cold and thermal neutrons. This project was funded by the National Science Foundation and the Department of Energy.

  15. On the absolute calibration of a DT fusion neutron yield diagnostic

    Directory of Open Access Journals (Sweden)

    Ruiz C.L.

    2013-11-01

    Full Text Available Recent advances in Inertial Confinement Fusion (ICF experiments at Lawrence Livermore National Laboratory's National Ignition Facility (NIF have underscored the need for accurate total yield measurements of DT neutrons because yield measurements provide a measure of the predicted performance of the experiments. Future gas-puff DT experiments at Sandia National Laboratory's Z facility will also require similar measurements. For ICF DT experiments, the standard technique for measuring the neutron (14.1 MeV yield, counts the activity (counts/minute induced in irradiated copper samples. This activity occurs by the 63Cu(n,2n62Cu reaction where 62Cu decays by positrons (β+ with a half-life of 9.67 minutes. The calibrations discussed here employ the associated-particle method (APM, where the α (4He particles from the T(d,n4He reaction are measured to infer neutron fluxes on a copper sample. The flux induces 62Cu activity, measured in a coincidence counting system. The method leads to a relationship between a DT neutron yield and copper activity known as the F-factor. The goal in future experiments is to apply this calibration to measure the yield at NIF with a combined uncertainty approaching 5%.

  16. Absolute efficiency calibration of 6LiF-based solid state thermal neutron detectors

    Science.gov (United States)

    Finocchiaro, Paolo; Cosentino, Luigi; Lo Meo, Sergio; Nolte, Ralf; Radeck, Desiree

    2018-03-01

    The demand for new thermal neutron detectors as an alternative to 3He tubes in research, industrial, safety and homeland security applications, is growing. These needs have triggered research and development activities about new generations of thermal neutron detectors, characterized by reasonable efficiency and gamma rejection comparable to 3He tubes. In this paper we show the state of the art of a promising low-cost technique, based on commercial solid state silicon detectors coupled with thin neutron converter layers of 6LiF deposited onto carbon fiber substrates. A few configurations were studied with the GEANT4 simulation code, and the intrinsic efficiency of the corresponding detectors was calibrated at the PTB Thermal Neutron Calibration Facility. The results show that the measured intrinsic detection efficiency is well reproduced by the simulations, therefore validating the simulation tool in view of new designs. These neutron detectors have also been tested at neutron beam facilities like ISIS (Rutherford Appleton Laboratory, UK) and n_TOF (CERN) where a few samples are already in operation for beam flux and 2D profile measurements. Forthcoming applications are foreseen for the online monitoring of spent nuclear fuel casks in interim storage sites.

  17. Instrument limitation of accuracy of absolute measurement by method of 4π beta-gamma coincidence

    International Nuclear Information System (INIS)

    Plkh, J.

    1979-01-01

    Accuracy is discussed of determination of coincidence channels dead-time in 4π β-γ installation and determination of coincidence resolution time as well as conditions for determination and accuracy of these parameters. Conditions are considered under which these parameters have not been determined and there is wrong performance of the installation. Special attention was paid to the electronic circuit of the γ-channel. It has been shown that as a result of wrong performance of electronic circuit a new type of wrong coincidence appeared [ru

  18. An absolute calibration method of an ethyl alcohol biosensor based on wavelength-modulated differential photothermal radiometry.

    Science.gov (United States)

    Liu, Yi Jun; Mandelis, Andreas; Guo, Xinxin

    2015-11-01

    In this work, laser-based wavelength-modulated differential photothermal radiometry (WM-DPTR) is applied to develop a non-invasive in-vehicle alcohol biosensor. WM-DPTR features unprecedented ethanol-specificity and sensitivity by suppressing baseline variations through a differential measurement near the peak and baseline of the mid-infrared ethanol absorption spectrum. Biosensor signal calibration curves are obtained from WM-DPTR theory and from measurements in human blood serum and ethanol solutions diffused from skin. The results demonstrate that the WM-DPTR-based calibrated alcohol biosensor can achieve high precision and accuracy for the ethanol concentration range of 0-100 mg/dl. The high-performance alcohol biosensor can be incorporated into ignition interlocks that could be fitted as a universal accessory in vehicles in an effort to reduce incidents of drinking and driving.

  19. Absolute, pressure-dependent validation of a calibration-free, airborne laser hygrometer transfer standard (SEALDH-II) from 5 to 1200 ppmv using a metrological humidity generator

    Science.gov (United States)

    Buchholz, Bernhard; Ebert, Volker

    2018-01-01

    Highly accurate water vapor measurements are indispensable for understanding a variety of scientific questions as well as industrial processes. While in metrology water vapor concentrations can be defined, generated, and measured with relative uncertainties in the single percentage range, field-deployable airborne instruments deviate even under quasistatic laboratory conditions up to 10-20 %. The novel SEALDH-II hygrometer, a calibration-free, tuneable diode laser spectrometer, bridges this gap by implementing a new holistic concept to achieve higher accuracy levels in the field. We present in this paper the absolute validation of SEALDH-II at a traceable humidity generator during 23 days of permanent operation at 15 different H2O mole fraction levels between 5 and 1200 ppmv. At each mole fraction level, we studied the pressure dependence at six different gas pressures between 65 and 950 hPa. Further, we describe the setup for this metrological validation, the challenges to overcome when assessing water vapor measurements on a high accuracy level, and the comparison results. With this validation, SEALDH-II is the first airborne, metrologically validated humidity transfer standard which links several scientific airborne and laboratory measurement campaigns to the international metrological water vapor scale.

  20. Flow rate calibration. III. The use of stabilized biostandards to calibrate the flow rate and calculate absolute CD4+ T-cell counts.

    Science.gov (United States)

    Walker, Clare L; Whitby, Liam; Granger, Viv; Storie, Ian; Reilly, John T; Barnett, David

    2006-05-01

    We have previously reported a flow rate calibration method for the determination of absolute CD4(+) T-lymphocyte counts that removes the need for the addition of latex beads to each sample. However, a limitation with this approach is that a calibration factor (CF) needs to be applied to adjust for differences in viscosity between latex bead suspensions and biological specimens. We have also demonstrated the value of using stabilized whole blood samples in external quality assessment (EQA) studies; such samples have a stable absolute lymphocyte count for over 1 year, at 4 degrees C. It was successfully demonstrated that this material can be used as a flow rate biocalibration (FRB) material for use as a flow cytometric control to provide a sample with a known CD4(+) T-lymphocyte count. Such material has advantages over latex bead technology as it can act as a full process control as well as having the same matrix and viscosity characteristics as the test material, thus removing the need for a CF. In this study, we have analyzed 268 consecutive normal, abnormal, and HIV(+) samples using FRB, incorporating the PanLeucoGating approach and compared this to the MultiSet method, defined as the predicate. Percentage similarity statistics revealed the following: 0-3,000 CD4(+) cells/mul mean percentage difference (MPD; bias) 1.2%, 95% CI of 5.6-8%; 0-200 CD4(+) cells/microl MPD of 1.25%, 95% CI of 11.63-14.13%; 201-500 CD4(+) cells/microl MPD of 1%, 95% CI of 4.6-6.6%. This study demonstrates that stabilized whole blood can be used for FRB. It has the advantage of being a full process control, in addition to costing less than latex beads with highly comparable results. As bench top flow cytometers are extremely stable, this is a low cost and robust alternative to bead based methods for generating absolute CD4 counts. Copyright 2006 International Society for Analytical Cytology.

  1. The effect of biomechanical variables on force sensitive resistor error: Implications for calibration and improved accuracy.

    Science.gov (United States)

    Schofield, Jonathon S; Evans, Katherine R; Hebert, Jacqueline S; Marasco, Paul D; Carey, Jason P

    2016-03-21

    Force Sensitive Resistors (FSRs) are commercially available thin film polymer sensors commonly employed in a multitude of biomechanical measurement environments. Reasons for such wide spread usage lie in the versatility, small profile, and low cost of these sensors. Yet FSRs have limitations. It is commonly accepted that temperature, curvature and biological tissue compliance may impact sensor conductance and resulting force readings. The effect of these variables and degree to which they interact has yet to be comprehensively investigated and quantified. This work systematically assesses varying levels of temperature, sensor curvature and surface compliance using a full factorial design-of-experiments approach. Three models of Interlink FSRs were evaluated. Calibration equations under 12 unique combinations of temperature, curvature and compliance were determined for each sensor. Root mean squared error, mean absolute error, and maximum error were quantified as measures of the impact these thermo/mechanical factors have on sensor performance. It was found that all three variables have the potential to affect FSR calibration curves. The FSR model and corresponding sensor geometry are sensitive to these three mechanical factors at varying levels. Experimental results suggest that reducing sensor error requires calibration of each sensor in an environment as close to its intended use as possible and if multiple FSRs are used in a system, they must be calibrated independently. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. [Evaluation of Measurement Accuracy and Inter-institutional Comparison for Dose Calibrators].

    Science.gov (United States)

    Matsutomo, Norikazu; Kangai, Yoshiharu; Yada, Nobuhiro; Kenda, Syuuji; Kai, Yuji; Maeda, Yukito; Sakai, Takayuki; Onishi, Hideo; Sasaki, Masayuki

    2016-05-01

    The aim of this study was to validate the reliability of dose calibrators for measuring the radioactivity of several radioisotopes in multi-institution. We evaluated the measurement accuracy of dose calibrators using a commercially available source ((67) Ga, (99m) Tc, (123) I, (201) TL). Nine dose calibrators (five models) in seven institutions were performed in this study. Each source was measured at least 3 times a day over a period of 4 half-life. Linearity of concentration (%error value) and percent difference values (%diff measurement) between measured and estimated radioactivity were calculated to evaluate the measurement accuracy. In addition, difference among institutions (%diff institution) was evaluated by the error values between measured and reference institution values. Good linearity of concentration was found between measured and estimated radioactivity in (99m)Tc and (123)I. However, %error value was increased in (67)Ga and (201)TL (maximum 19.3%). %diff measurements were 1.9 ± 0.3% for (67)Ga, -0.9 ± 0.3% for (99m)Tc, 2.2 ± 0.4% for (123)I, and -0.7 ± 0.3% for (201)TL, respectively. Although there were no clear differences in six institutions, %diff institution in one institution tended to be higher than that obtained in other institutions. Our results indicated that measurement accuracy of nine dose calibrators (five models) was relatively stable. However, difference of measured values tended to be higher in a part of institution and source. It is important to perform quality assurance and quality control for dose calibrator using traceable source.

  3. Analysis on detection accuracy of binocular photoelectric instrument optical axis parallelism digital calibration instrument

    Science.gov (United States)

    Ying, Jia-ju; Yin, Jian-ling; Wu, Dong-sheng; Liu, Jie; Chen, Yu-dan

    2017-11-01

    Low-light level night vision device and thermal infrared imaging binocular photoelectric instrument are used widely. The maladjustment of binocular instrument ocular axises parallelism will cause the observer the symptom such as dizziness, nausea, when use for a long time. Binocular photoelectric equipment digital calibration instrument is developed for detecting ocular axises parallelism. And the quantitative value of optical axis deviation can be quantitatively measured. As a testing instrument, the precision must be much higher than the standard of test instrument. Analyzes the factors that influence the accuracy of detection. Factors exist in each testing process link which affect the precision of the detecting instrument. They can be divided into two categories, one category is factors which directly affect the position of reticle image, the other category is factors which affect the calculation the center of reticle image. And the Synthesize error is calculated out. And further distribute the errors reasonably to ensure the accuracy of calibration instruments.

  4. Optimizing the accuracy of a helical diode array dosimeter: A comprehensive calibration methodology coupled with a novel virtual inclinometer

    Energy Technology Data Exchange (ETDEWEB)

    Kozelka, Jakub; Robinson, Joshua; Nelms, Benjamin; Zhang, Geoffrey; Savitskij, Dennis; Feygelman, Vladimir [Sun Nuclear Corp., Melbourne, Florida 32940 (United States); Department of Physics, University of South Florida, Tampa, Florida 33612 (United States); Canis Lupus LLC, Sauk County, Wisconsin 53561 (United States); Division of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States); Sun Nuclear Corp., Melbourne, Florida 32940 (United States); Division of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States)

    2011-09-15

    Purpose: The goal of any dosimeter is to be as accurate as possible when measuring absolute dose to compare with calculated dose. This limits the uncertainties associated with the dosimeter itself and allows the task of dose QA to focus on detecting errors in the treatment planning (TPS) and/or delivery systems. This work introduces enhancements to the measurement accuracy of a 3D dosimeter comprised of a helical plane of diodes in a volumetric phantom. Methods: We describe the methods and derivations of new corrections that account for repetition rate dependence, intrinsic relative sensitivity per diode, field size dependence based on the dynamic field size determination, and positional correction. Required and described is an accurate ''virtual inclinometer'' algorithm. The system allows for calibrating the array directly against an ion chamber signal collected with high angular resolution. These enhancements are quantitatively validated using several strategies including ion chamber measurements taken using a ''blank'' plastic shell mimicking the actual phantom, and comparison to high resolution dose calculations for a variety of fields: static, simple arcs, and VMAT. A number of sophisticated treatment planning algorithms were benchmarked against ion chamber measurements for their ability to handle a large air cavity in the phantom. Results: Each calibration correction is quantified and presented vs its independent variable(s). The virtual inclinometer is validated by direct comparison to the gantry angle vs time data from machine log files. The effects of the calibration are quantified and improvements are seen in the dose agreement with the ion chamber reference measurements and with the TPS calculations. These improved agreements are a result of removing prior limitations and assumptions in the calibration methodology. Average gamma analysis passing rates for VMAT plans based on the AAPM TG-119 report are 98.4 and 93

  5. Automated Gravimetric Calibration to Optimize the Accuracy and Precision of TECAN Freedom EVO Liquid Handler.

    Science.gov (United States)

    Bessemans, Laurent; Jully, Vanessa; de Raikem, Caroline; Albanese, Mathieu; Moniotte, Nicolas; Silversmet, Pascal; Lemoine, Dominique

    2016-10-01

    High-throughput screening technologies are increasingly integrated into the formulation development process of biopharmaceuticals. The performance of liquid handling systems is dependent on the ability to deliver accurate and precise volumes of specific reagents to ensure process quality. We have developed an automated gravimetric calibration procedure to adjust the accuracy and evaluate the precision of the TECAN Freedom EVO liquid handling system. Volumes from 3 to 900 µL using calibrated syringes and fixed tips were evaluated with various solutions, including aluminum hydroxide and phosphate adjuvants, β-casein, sucrose, sodium chloride, and phosphate-buffered saline. The methodology to set up liquid class pipetting parameters for each solution was to split the process in three steps: (1) screening of predefined liquid class, including different pipetting parameters; (2) adjustment of accuracy parameters based on a calibration curve; and (3) confirmation of the adjustment. The run of appropriate pipetting scripts, data acquisition, and reports until the creation of a new liquid class in EVOware was fully automated. The calibration and confirmation of the robotic system was simple, efficient, and precise and could accelerate data acquisition for a wide range of biopharmaceutical applications. © 2016 Society for Laboratory Automation and Screening.

  6. DAQ Software Contributions, Absolute Scale Energy Calibration and Background Evaluation for the NOvA Experiment at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Flumerfelt, Eric Lewis [Univ. of Tennessee, Knoxville, TN (United States)

    2015-08-01

    The NOvA (NuMI Off-axis ve [nu_e] Appearance) Experiment is a long-baseline accelerator neutrino experiment currently in its second year of operations. NOvA uses the Neutrinos from the Main Injector (NuMI) beam at Fermilab, and there are two main off-axis detectors: a Near Detector at Fermilab and a Far Detector 810 km away at Ash River, MN. The work reported herein is in support of the NOvA Experiment, through contributions to the development of data acquisition software, providing an accurate, absolute-scale energy calibration for electromagnetic showers in NOvA detector elements, crucial to the primary electron neutrino search, and through an initial evaluation of the cosmic background rate in the NOvA Far Detector, which is situated on the surface without significant overburden. Additional support work for the NOvA Experiment is also detailed, including DAQ Server Administration duties and a study of NOvA’s sensitivity to neutrino oscillations into a “sterile” state.

  7. Improving plasma shaping accuracy through consolidation of control model maintenance, diagnostic calibration, and hardware change control

    International Nuclear Information System (INIS)

    Baggest, D.S.; Rothweil, D.A.; Pang, S.

    1995-12-01

    With the advent of more sophisticated techniques for control of tokamak plasmas comes the requirement for increasingly more accurate models of plasma processes and tokamak systems. Development of accurate models for DIII-D power systems, vessel, and poloidal coils is already complete, while work continues in development of general plasma response modeling techniques. Increased accuracy in estimates of parameters to be controlled is also required. It is important to ensure that errors in supporting systems such as diagnostic and command circuits do not limit the accuracy of plasma parameter estimates or inhibit the ability to derive accurate plasma/tokamak system models. To address this issue, we have developed more formal power systems change control and power system/magnetic diagnostics calibration procedures. This paper discusses our approach to consolidating the tasks in these closely related areas. This includes, for example, defining criteria for when diagnostics should be re-calibrated along with required calibration tolerances, and implementing methods for tracking power systems hardware modifications and the resultant changes to control models

  8. Analysis of the accuracy of absolute measurements of high d.c. voltages by means of (p,γ)-compound-nucleus reactions

    International Nuclear Information System (INIS)

    Weissmueller, G.

    1987-01-01

    Absolute measurement of high d.c. voltages by means of (p,γ)-compound nucleus-reactions is based on the determination of the kinetic energy of charged particles which are accelerated in the electrostatic field of the high voltage to be measured. The particle energy is equivalent to the product of beam potential and particle charge and thus affords a simple means of inverse calculation of high d.c. voltages. On the basis of the physics of compound-nucleus reactions and the analysis of various natural and plant-specific, potential causes of error, special demands are to be made on the electrostatic acceleration device used to carry through the (p,γ)-nuclear resonance process, which were taken into account in the planning and technical realization of the extensive test device. The discussion of target properties entailing impaired accuracy led to the presentation of a fork process using staggered targets. By that process a close energy interval can be established which is sure to encompass the locus of the natural resonance energy. The conditions governing this process for the location of nuclear resonance are easily verifiable by measurements, independently of the magnitude of plant-dependent factors of error; it is a process yielding accuracies in the range of tenths per mil supposing an optimum test device. Contrary to resistance measuring bridges, the fork process in combination with the electrostatic 800-keV proton accelerator permits calibration of high-ohmic resistors and voltage dividers for rated voltages of up to 800 kV, taking into account possible non-linearity effects. (orig.) With 66 figs., 4 tabs [de

  9. Radiometric inter-sensor cross-calibration uncertainty using a traceable high accuracy reference hyperspectral imager

    Science.gov (United States)

    Gorroño, Javier; Banks, Andrew C.; Fox, Nigel P.; Underwood, Craig

    2017-08-01

    Optical earth observation (EO) satellite sensors generally suffer from drifts and biases relative to their pre-launch calibration, caused by launch and/or time in the space environment. This places a severe limitation on the fundamental reliability and accuracy that can be assigned to satellite derived information, and is particularly critical for long time base studies for climate change and enabling interoperability and Analysis Ready Data. The proposed TRUTHS (Traceable Radiometry Underpinning Terrestrial and Helio-Studies) mission is explicitly designed to address this issue through re-calibrating itself directly to a primary standard of the international system of units (SI) in-orbit and then through the extension of this SI-traceability to other sensors through in-flight cross-calibration using a selection of Committee on Earth Observation Satellites (CEOS) recommended test sites. Where the characteristics of the sensor under test allows, this will result in a significant improvement in accuracy. This paper describes a set of tools, algorithms and methodologies that have been developed and used in order to estimate the radiometric uncertainty achievable for an indicative target sensor through in-flight cross-calibration using a well-calibrated hyperspectral SI-traceable reference sensor with observational characteristics such as TRUTHS. In this study, Multi-Spectral Imager (MSI) of Sentinel-2 and Landsat-8 Operational Land Imager (OLI) is evaluated as an example, however the analysis is readily translatable to larger-footprint sensors such as Sentinel-3 Ocean and Land Colour Instrument (OLCI) and Visible Infrared Imaging Radiometer Suite (VIIRS). This study considers the criticality of the instrumental and observational characteristics on pixel level reflectance factors, within a defined spatial region of interest (ROI) within the target site. It quantifies the main uncertainty contributors in the spectral, spatial, and temporal domains. The resultant tool

  10. Accuracy enhancement of a multivariate calibration for lead determination in soils by laser induced breakdown spectroscopy

    Science.gov (United States)

    Zaytsev, Sergey M.; Krylov, Ivan N.; Popov, Andrey M.; Zorov, Nikita B.; Labutin, Timur A.

    2018-02-01

    We have investigated matrix effects and spectral interferences on example of lead determination in different types of soils by laser induced breakdown spectroscopy (LIBS). Comparison between analytical performances of univariate and multivariate calibrations with the use of different laser wavelength for ablation (532, 355 and 266 nm) have been reported. A set of 17 soil samples (Ca-rich, Fe-rich, lean soils etc., 8.5-280 ppm of Pb) was involved into construction of the calibration models. Spectral interferences from main components (Ca, Fe, Ti, Mg) and trace components (Mn, Nb, Zr) were estimated by spectra modeling, and they were a reason for significant differences between the univariate calibration models obtained for a three different soil types (black, red, gray) separately. Implementation of 3rd harmonic of Nd:YAG laser in combination with multivariate calibration model based on PCR with 3 principal components provided the best analytical results: the RMSEC has been lowered down to 8 ppm. The sufficient improvement of the relative uncertainty (up to 5-10%) in comparison with univariate calibration was observed at the Pb concentration level > 50 ppm, while the problem of accuracy still remains for some samples with Pb concentration at the 20 ppm level. We have also discussed a few possible ways to estimate LOD without a blank sample. The most rigorous criterion has resulted in LOD of Pb in soils being 13 ppm. Finally, a good agreement between the values of lead content predicted by LIBS (46 ± 5 ppm) and XRF (42.1 ± 3.3 ppm) in the unknown soil sample from Lomonosov Moscow State University area was demonstrated.

  11. The Effect of a New Calibration Procedure on the Measurement Accuracy of Scintec's Displaced-Beam Laser Scintillometer

    NARCIS (Netherlands)

    Kesteren, van A.J.H.; Hartogensis, O.K.; Kroonenberg, van den A.C.

    2014-01-01

    We describe a new calibration procedure included in the production process of Scintec’s displaced-beam laser scintillometers (SLS-20/40) and its effect on their measurement accuracy. The calibration procedure determines the factual displacement distances of the laser beams at the receiver and

  12. Investigation into the accuracy of a proposed laser diode based multilateration machine tool calibration system

    International Nuclear Information System (INIS)

    Fletcher, S; Longstaff, A P; Myers, A

    2005-01-01

    Geometric and thermal calibration of CNC machine tools is required in modern machine shops with volumetric accuracy assessment becoming the standard machine tool qualification in many industries. Laser interferometry is a popular method of measuring the errors but this, and other alternatives, tend to be expensive, time consuming or both. This paper investigates the feasibility of using a laser diode based system that capitalises on the low cost nature of the diode to provide multiple laser sources for fast error measurement using multilateration. Laser diode module technology enables improved wavelength stability and spectral linewidth which are important factors for laser interferometry. With more than three laser sources, the set-up process can be greatly simplified while providing flexibility in the location of the laser sources improving the accuracy of the system

  13. Accuracy improvement in a calibration test bench for accelerometers by a vision system

    Energy Technology Data Exchange (ETDEWEB)

    D’Emilia, Giulio, E-mail: giulio.demilia@univaq.it; Di Gasbarro, David, E-mail: david.digasbarro@graduate.univaq.it; Gaspari, Antonella, E-mail: antonella.gaspari@graduate.univaq.it; Natale, Emanuela, E-mail: emanuela.natale@univaq.it [University of L’Aquila, Department of Industrial and Information Engineering and Economics (DIIIE), via G. Gronchi, 18, 67100 L’Aquila (Italy)

    2016-06-28

    A procedure is described in this paper for the accuracy improvement of calibration of low-cost accelerometers in a prototype rotary test bench, driven by a brushless servo-motor and operating in a low frequency range of vibrations (0 to 5 Hz). Vibration measurements by a vision system based on a low frequency camera have been carried out, in order to reduce the uncertainty of the real acceleration evaluation at the installation point of the sensor to be calibrated. A preliminary test device has been realized and operated in order to evaluate the metrological performances of the vision system, showing a satisfactory behavior if the uncertainty measurement is taken into account. A combination of suitable settings of the control parameters of the motion control system and of the information gained by the vision system allowed to fit the information about the reference acceleration at the installation point to the needs of the procedure for static and dynamic calibration of three-axis accelerometers.

  14. Absolute sensitivity calibration from 20 A to 430 A of a grazing incidence spectrometer with a multi-element spectral detector

    International Nuclear Information System (INIS)

    Terry, J.L.; Manning, H.L.; Marmar, E.S.

    1986-07-01

    Two methods which together allow sensitivity calibration from 20 A to 430 A are described in detail. The first method, useful up to 120 A, uses a low power source to generate Kα x-rays which are alternately viewed by an absolute detector (a proportional counter) and the spectrometer. The second method extends that calibration to 430 A. It relies on the 2:1 brightness ratio of bright doublet lines from impurity ions which have a single outer shell electron and which are present in hot, magnetically confined plasmas. It requires that the absolute sensitivity of the spectrometer be known at one wavelength point, and in practice requires a multi-element spectral detector

  15. Contributed Review: Absolute spectral radiance calibration of fiber-optic shock-temperature pyrometers using a coiled-coil irradiance standard lamp.

    Science.gov (United States)

    Fat'yanov, O V; Asimow, P D

    2015-10-01

    We describe an accurate and precise calibration procedure for multichannel optical pyrometers such as the 6-channel, 3-ns temporal resolution instrument used in the Caltech experimental geophysics laboratory. We begin with a review of calibration sources for shock temperatures in the 3000-30,000 K range. High-power, coiled tungsten halogen standards of spectral irradiance appear to be the only practical alternative to NIST-traceable tungsten ribbon lamps, which are no longer available with large enough calibrated area. However, non-uniform radiance complicates the use of such coiled lamps for reliable and reproducible calibration of pyrometers that employ imaging or relay optics. Careful analysis of documented methods of shock pyrometer calibration to coiled irradiance standard lamps shows that only one technique, not directly applicable in our case, is free of major radiometric errors. We provide a detailed description of the modified Caltech pyrometer instrument and a procedure for its absolute spectral radiance calibration, accurate to ±5%. We employ a designated central area of a 0.7× demagnified image of a coiled-coil tungsten halogen lamp filament, cross-calibrated against a NIST-traceable tungsten ribbon lamp. We give the results of the cross-calibration along with descriptions of the optical arrangement, data acquisition, and processing. We describe a procedure to characterize the difference between the static and dynamic response of amplified photodetectors, allowing time-dependent photodiode correction factors for spectral radiance histories from shock experiments. We validate correct operation of the modified Caltech pyrometer with actual shock temperature experiments on single-crystal NaCl and MgO and obtain very good agreement with the literature data for these substances. We conclude with a summary of the most essential requirements for error-free calibration of a fiber-optic shock-temperature pyrometer using a high-power coiled tungsten halogen

  16. Contributed Review: Absolute spectral radiance calibration of fiber-optic shock-temperature pyrometers using a coiled-coil irradiance standard lamp

    Science.gov (United States)

    Fat'yanov, O. V.; Asimow, P. D.

    2015-10-01

    We describe an accurate and precise calibration procedure for multichannel optical pyrometers such as the 6-channel, 3-ns temporal resolution instrument used in the Caltech experimental geophysics laboratory. We begin with a review of calibration sources for shock temperatures in the 3000-30 000 K range. High-power, coiled tungsten halogen standards of spectral irradiance appear to be the only practical alternative to NIST-traceable tungsten ribbon lamps, which are no longer available with large enough calibrated area. However, non-uniform radiance complicates the use of such coiled lamps for reliable and reproducible calibration of pyrometers that employ imaging or relay optics. Careful analysis of documented methods of shock pyrometer calibration to coiled irradiance standard lamps shows that only one technique, not directly applicable in our case, is free of major radiometric errors. We provide a detailed description of the modified Caltech pyrometer instrument and a procedure for its absolute spectral radiance calibration, accurate to ±5%. We employ a designated central area of a 0.7× demagnified image of a coiled-coil tungsten halogen lamp filament, cross-calibrated against a NIST-traceable tungsten ribbon lamp. We give the results of the cross-calibration along with descriptions of the optical arrangement, data acquisition, and processing. We describe a procedure to characterize the difference between the static and dynamic response of amplified photodetectors, allowing time-dependent photodiode correction factors for spectral radiance histories from shock experiments. We validate correct operation of the modified Caltech pyrometer with actual shock temperature experiments on single-crystal NaCl and MgO and obtain very good agreement with the literature data for these substances. We conclude with a summary of the most essential requirements for error-free calibration of a fiber-optic shock-temperature pyrometer using a high-power coiled tungsten halogen

  17. Contributed Review: Absolute spectral radiance calibration of fiber-optic shock-temperature pyrometers using a coiled-coil irradiance standard lamp

    Energy Technology Data Exchange (ETDEWEB)

    Fat’yanov, O. V., E-mail: fatyan1@gps.caltech.edu; Asimow, P. D., E-mail: asimow@gps.caltech.edu [Division of Geological and Planetary Sciences 252-21, California Institute of Technology, Pasadena, California 91125 (United States)

    2015-10-15

    We describe an accurate and precise calibration procedure for multichannel optical pyrometers such as the 6-channel, 3-ns temporal resolution instrument used in the Caltech experimental geophysics laboratory. We begin with a review of calibration sources for shock temperatures in the 3000-30 000 K range. High-power, coiled tungsten halogen standards of spectral irradiance appear to be the only practical alternative to NIST-traceable tungsten ribbon lamps, which are no longer available with large enough calibrated area. However, non-uniform radiance complicates the use of such coiled lamps for reliable and reproducible calibration of pyrometers that employ imaging or relay optics. Careful analysis of documented methods of shock pyrometer calibration to coiled irradiance standard lamps shows that only one technique, not directly applicable in our case, is free of major radiometric errors. We provide a detailed description of the modified Caltech pyrometer instrument and a procedure for its absolute spectral radiance calibration, accurate to ±5%. We employ a designated central area of a 0.7× demagnified image of a coiled-coil tungsten halogen lamp filament, cross-calibrated against a NIST-traceable tungsten ribbon lamp. We give the results of the cross-calibration along with descriptions of the optical arrangement, data acquisition, and processing. We describe a procedure to characterize the difference between the static and dynamic response of amplified photodetectors, allowing time-dependent photodiode correction factors for spectral radiance histories from shock experiments. We validate correct operation of the modified Caltech pyrometer with actual shock temperature experiments on single-crystal NaCl and MgO and obtain very good agreement with the literature data for these substances. We conclude with a summary of the most essential requirements for error-free calibration of a fiber-optic shock-temperature pyrometer using a high-power coiled tungsten halogen

  18. Impacts of the spatial extent of pollen-climate calibration-set on the absolute values, range and trends of reconstructed Holocene precipitation

    Science.gov (United States)

    Cao, Xianyong; Tian, Fang; Telford, Richard J.; Ni, Jian; Xu, Qinghai; Chen, Fahu; Liu, Xingqi; Stebich, Martina; Zhao, Yan; Herzschuh, Ulrike

    2017-12-01

    Pollen-based quantitative reconstructions of past climate variables is a standard palaeoclimatic approach. Despite knowing that the spatial extent of the calibration-set affects the reconstruction result, guidance is lacking as to how to determine a suitable spatial extent of the pollen-climate calibration-set. In this study, past mean annual precipitation (Pann) during the Holocene (since 11.5 cal ka BP) is reconstructed repeatedly for pollen records from Qinghai Lake (36.7°N, 100.5°E; north-east Tibetan Plateau), Gonghai Lake (38.9°N, 112.2°E; north China) and Sihailongwan Lake (42.3°N, 126.6°E; north-east China) using calibration-sets of varying spatial extents extracted from the modern pollen dataset of China and Mongolia (2559 sampling sites and 168 pollen taxa in total). Results indicate that the spatial extent of the calibration-set has a strong impact on model performance, analogue quality and reconstruction diagnostics (absolute value, range, trend, optimum). Generally, these effects are stronger with the modern analogue technique (MAT) than with weighted averaging partial least squares (WA-PLS). With respect to fossil spectra from northern China, the spatial extent of calibration-sets should be restricted to radii between ca. 1000 and 1500 km because small-scale calibration-sets (1500 km radius) will include taxa with very different pollen-climate relationships.

  19. A simple and effective calibration method to determine the accuracy of liquid-handling nano-dispenser devices

    International Nuclear Information System (INIS)

    Rodríguez-Puente, Sonia; Linacero-Blanco, Judith; Guasch, Alicia

    2013-01-01

    A simple fluorescence-based calibration method that can be used to monitor the precision and accuracy of any liquid-handling nano-dispenser device is presented. The accurate delivery of small volumes is a critical factor in the crystallization of macromolecules as it influences the reproducibility of the screening experiments. Crystallographic screening technologies have made it possible to perform experiments using volumes as low as 50 nl. The accuracy of the dispenser has usually been calibrated by weight measurements. In this work, a simple and inexpensive fluorescence-based calibration method that is sensitive and that can be used to monitor the precision and accuracy of any liquid-handling nano-dispenser device is presented. The results suggest that the protocol described here can be useful to determine volumes ranging from 50 to 300 nl with precision. Therefore, the pipetting of volumes as low as 50 nl can be calibrated periodically to ensure that precision and accuracy are maintained. The suggested calibration protocol can be executed in 6 h per instrument, including the calibration curve, which is the most time-consuming step; the rest can be completed in approximately 2 h

  20. Validation of early GOES-16 ABI on-orbit geometrical calibration accuracy using SNO method

    Science.gov (United States)

    Yu, Fangfang; Shao, Xi; Wu, Xiangqian; Kondratovich, Vladimir; Li, Zhengping

    2017-09-01

    The Advanced Baseline Imager (ABI) onboard the GOES-16 satellite, which was launched on 19 November 2016, is the first next-generation geostationary weather instrument in the west hemisphere. It has 16 spectral solar reflective and emissive bands located in three focal plane modules (FPM): one visible and near infrared (VNIR) FPM, one midwave infrared (MWIR), and one longwave infrared (LWIR) FPM. All the ABI bands are geometeorically calibrated with new techniques of Kalman filtering and Global Positioning System (GPS) to determine the accurate spacecraft attitude and orbit configuration to meet the challenging image navigation and registration (INR) requirements of ABI data. This study is to validate the ABI navigation and band-to-band registration (BBR) accuracies using the spectrally matched pixels of the Suomi National Polar-orbiting Partnership (SNPP) Visible Infrared Imaging Radiometer Suite (VIIRS) M-band data and the ABI images from the Simultaneous Nadir Observation (SNO) images. The preliminary results showed that during the ABI post-launch product test (PLPT) period, the ABI BBR errors at the y-direction (along the VIIRS track direction) is smaller than at the x-direction (along the VIIRS scan direction). Variations in the ABI BBR calibration residuals and navigation difference to VIIRS can be observed. Note that ABI is not operational yet and the data is experimental and still under testing. Effort is still ongoing to improve the ABI data quality.

  1. High-accuracy X-ray detector calibration based on cryogenic radiometry

    Science.gov (United States)

    Krumrey, M.; Cibik, L.; Müller, P.

    2010-06-01

    Cryogenic electrical substitution radiometers (ESRs) are absolute thermal detectors, based on the equivalence of electrical power and radiant power. Their core piece is a cavity absorber, which is typically made of copper to achieve a short response time. At higher photon energies, the use of copper prevents the operation of ESRs due to increasing transmittance. A new absorber design for hard X-rays has been developed at the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the electron storage ring BESSY II. The Monte Carlo simulation code Geant4 was applied to optimize its absorptance for photon energies of up to 60 keV. The measurement of the radiant power of monochromatized synchrotron radiation was achieved with relative standard uncertainties of less than 0.2 %, covering the entire photon energy range of three beamlines from 50 eV to 60 keV. Monochromatized synchrotron radiation of high spectral purity is used to calibrate silicon photodiodes against the ESR for photon energies up to 60 keV with relative standard uncertainties below 0.3 %. For some silicon photodiodes, the photocurrent is not linear with the incident radiant power.

  2. High-accuracy X-ray detector calibration based on cryogenic radiometry

    International Nuclear Information System (INIS)

    Krumrey, M.; Cibik, L.; Mueller, P.

    2010-01-01

    Cryogenic electrical substitution radiometers (ESRs) are absolute thermal detectors, based on the equivalence of electrical power and radiant power. Their core piece is a cavity absorber, which is typically made of copper to achieve a short response time. At higher photon energies, the use of copper prevents the operation of ESRs due to increasing transmittance. A new absorber design for hard X-rays has been developed at the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the electron storage ring BESSY II. The Monte Carlo simulation code Geant4 was applied to optimize its absorptance for photon energies of up to 60 keV. The measurement of the radiant power of monochromatized synchrotron radiation was achieved with relative standard uncertainties of less than 0.2 %, covering the entire photon energy range of three beamlines from 50 eV to 60 keV. Monochromatized synchrotron radiation of high spectral purity is used to calibrate silicon photodiodes against the ESR for photon energies up to 60 keV with relative standard uncertainties below 0.3 %. For some silicon photodiodes, the photocurrent is not linear with the incident radiant power.

  3. A test object with parallel grooves for calibration and accuracy assessment of industrial computed tomography (CT) metrology

    Science.gov (United States)

    Kiekens, K.; Welkenhuyzen, F.; Tan, Y.; Bleys, Ph; Voet, A.; Kruth, J.-P.; Dewulf, W.

    2011-11-01

    While computed tomography (CT) has long been used for medical applications and material inspection, its application field has recently been broadened to include industrial dimensional metrology. However, the accuracy of CT-based measurements remains yet largely uncertain. Not only are the measurements influenced by a number of factors and parameters like e.g. workpiece orientation, magnification, edge detection and so on, but also the calibration method matters greatly. This paper investigates the influence of these factors and parameters and the calibration method (rescaling and correction) on accuracy and repeatability of the measurements, using a test object with parallel grooves. The test object is also used to illustrate how more accurate CMM measurements can be used to calibrate CT measurements and to compare different calibration and compensation strategies. This paper was presented at ISMQC-2010, the 10th International Symposium on Measurement and Quality Control, held in Osaka, Japan, on 5-9 September 2010.

  4. Piston manometer as an absolute standard for vacuum-gage calibration in the range 2 to 500 millitorr

    Science.gov (United States)

    Warshawsky, I.

    1972-01-01

    A thin disk is suspended, with very small annular clearance, in a cylindrical opening in the base plate of a calibration chamber. A continuous flow of calibration gas passes through the chamber and annular opening to a downstream high vacuum pump. The ratio of pressures on the two faces of the disk is very large, so that the upstream pressure is substantially equal to net force on the disk divided by disk area. This force is measured with a dynamometer that is calibrated in place with dead weights. A probable error of + or - (0.2 millitorr plus 0.2 percent) is attainable when downstream pressure is known to 10 percent.

  5. Environmental dosimetry of radon-222 and daughters: measurement of absolute calibration factors of CR-39 considering the plate-out effects and environmental factors

    International Nuclear Information System (INIS)

    Paulo, S.R. de.

    1991-08-01

    The subject of this work concerns with the measurement of absolute calibration factors for the use of CR-39 as an absolute detector in indoor and daughters monitoring. Up to now the usefulness of calibration factors was restricted to environmental conditions equal (or very close) to those worthing during their determinations. This fact is consequence of the difficulties related to the understanding of the plate-out properties of radon daughters activity in the air. The plate-out effects on radon daughters monitoring performed by SSNTDs are studied. Our experimental results are in agreement with those of other authors about the great sensitivity of CR-39 to the plate-out effects, fact that recommended its use in this work. Being succeeded in the employment of CR-39 as an alpha-spectrometer we concluded that some important information (like the radon daughters deposition rates on the walls of an environment) can be achieved. The knowledge about the behavior of plate-out made possible the determination of the ranges in zenithal angle and energy where CR-39 can detect alpha-particles with efficiency of 100%, at our conditions of track observation. In this way, we obtained calibration factors for CR-39 that are weakly dependent on environmental conditions. We think that these results can contribute to the improvement of RD (Radiation Detector) detection techniques. (author). 159 refs, 106 figs, 05 tabs

  6. SYSTEMATIC UNCERTAINTIES IN THE SPECTROSCOPIC MEASUREMENTS OF NEUTRON STAR MASSES AND RADII FROM THERMONUCLEAR X-RAY BURSTS. III. ABSOLUTE FLUX CALIBRATION

    Energy Technology Data Exchange (ETDEWEB)

    Güver, Tolga [Istanbul University, Science Faculty, Department of Astronomy and Space Sciences, Beyazıt, 34119, Istanbul (Turkey); Özel, Feryal; Psaltis, Dimitrios [Department of Astronomy, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Marshall, Herman [Center for Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Guainazzi, Matteo [European Space Astronomy Centre of ESA, P.O. Box 78, Villanueva de la Cañada, E-28691 Madrid (Spain); Díaz-Trigo, Maria [ESO, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany)

    2016-09-20

    Many techniques for measuring neutron star radii rely on absolute flux measurements in the X-rays. As a result, one of the fundamental uncertainties in these spectroscopic measurements arises from the absolute flux calibrations of the detectors being used. Using the stable X-ray burster, GS 1826–238, and its simultaneous observations by Chandra HETG/ACIS-S and RXTE /PCA as well as by XMM-Newton EPIC-pn and RXTE /PCA, we quantify the degree of uncertainty in the flux calibration by assessing the differences between the measured fluxes during bursts. We find that the RXTE /PCA and the Chandra gratings measurements agree with each other within their formal uncertainties, increasing our confidence in these flux measurements. In contrast, XMM-Newton EPIC-pn measures 14.0 ± 0.3% less flux than the RXTE /PCA. This is consistent with the previously reported discrepancy with the flux measurements of EPIC-pn, compared with EPIC MOS1, MOS2, and ACIS-S detectors. We also show that any intrinsic time-dependent systematic uncertainty that may exist in the calibration of the satellites has already been implicity taken into account in the neutron star radius measurements.

  7. On the accuracy of Hipparcos using binary stars as a calibration tool

    Energy Technology Data Exchange (ETDEWEB)

    Docobo, J. A.; Andrade, M., E-mail: joseangel.docobo@usc.es, E-mail: manuel.andrade@usc.es [R. M. Aller Astronomical Observatory, University of Santiago de Compostela (USC), Santiago de Compostela E-15782, Galiza, P.O. Box 197 (Spain)

    2015-02-01

    Stellar binary systems, specifically those that present the most accurate available orbital elements, are a reliable tool to test the accuracy of astrometric observations. We selected all 35 binaries with these characteristics. Our objective is to provide standard uncertainties for the positions and parallaxes measured by Hipparcos relative to this trustworthy set, as well as to check supposed correlations between several parameters (measurement residuals, positions, magnitudes, and parallaxes). In addition, using the high-confidence subset of visual–spectroscopic binaries, we implemented a validation test of the Hipparcos trigonometric parallaxes of binary systems that allowed the evaluation of their reliability. Standard and non-standard statistical analysis techniques were applied in order to achieve well-founded conclusions. In particular, errors-in-variables models such as the total least-squares method were used to validate Hipparcos parallaxes by comparison with those obtained directly from the orbital elements. Previously, we executed Thompson's τ technique in order to detect suspected outliers in the data. Furthermore, several statistical hypothesis tests were carried out to verify if our results were statistically significant. A statistically significant trend indicating larger Hipparcos angular separations with respect to the reference values in 5.2 ± 1.4 mas was found at the 10{sup −8} significance level. Uncertainties in the polar coordinates θ and ρ of 1.°8 and 6.3 mas, respectively, were estimated for the Hipparcos observations of binary systems. We also verified that the parallaxes of binary systems measured in this mission are absolutely compatible with the set of orbital parallaxes obtained from the most accurate orbits at least at the 95% confidence level. This methodology allows us to better estimate the accuracy of Hipparcos observations of binary systems. Indeed, further application to the data collected by Gaia should yield a

  8. Absolute dose calibration of an X-ray system and dead time investigations of photon-counting techniques

    CERN Document Server

    Carpentieri, C; Ludwig, J; Ashfaq, A; Fiederle, M

    2002-01-01

    High precision concerning the dose calibration of X-ray sources is required when counting and integrating methods are compared. The dose calibration for a dental X-ray tube was executed with special dose calibration equipment (dosimeter) as function of exposure time and rate. Results were compared with a benchmark spectrum and agree within +-1.5%. Dead time investigations with the Medipix1 photon-counting chip (PCC) have been performed by rate variations. Two different types of dead time, paralysable and non-paralysable will be discussed. The dead time depends on settings of the front-end electronics and is a function of signal height, which might lead to systematic defects of systems. Dead time losses in excess of 30% have been found for the PCC at 200 kHz absorbed photons per pixel.

  9. Piston manometer as an absolute standard for vacuum gage calibration in the range 10 to 700 microtorr

    Science.gov (United States)

    Warshawsky, I.

    1972-01-01

    Total pressure in a calibration chamber is determined by measuring the force on a disk suspended in an orifice in the baseplate of the chamber. The disk forms a narrow annular gap with the orifice. A continuous flow of calibration gas passes through the chamber and annulus to a downstream pumping system. The ratio of pressures on the two faces of the disk exceeds 100:1, so that chamber pressure is substantially equal to the product of disk area and net force on the disk. This force is measured with an electrodynamometer that can be calibrated in situ with dead weights. Probable error in pressure measurement is plus or minus (0.5 microtorr + 0.6 percent).

  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. A simple and effective calibration method to determine the accuracy of liquid-handling nano-dispenser devices.

    Science.gov (United States)

    Rodríguez-Puente, Sonia; Linacero-Blanco, Judith; Guasch, Alicia

    2013-03-01

    The accurate delivery of small volumes is a critical factor in the crystallization of macromolecules as it influences the reproducibility of the screening experiments. Crystallographic screening technologies have made it possible to perform experiments using volumes as low as 50 nl. The accuracy of the dispenser has usually been calibrated by weight measurements. In this work, a simple and inexpensive fluorescence-based calibration method that is sensitive and that can be used to monitor the precision and accuracy of any liquid-handling nano-dispenser device is presented. The results suggest that the protocol described here can be useful to determine volumes ranging from 50 to 300 nl with precision. Therefore, the pipetting of volumes as low as 50 nl can be calibrated periodically to ensure that precision and accuracy are maintained. The suggested calibration protocol can be executed in 6 h per instrument, including the calibration curve, which is the most time-consuming step; the rest can be completed in approximately 2 h.

  12. Accuracy of calibrated data from the SDSS moving object catalog, absolute magnitudes, and probable lightcurves for several asteroids

    Czech Academy of Sciences Publication Activity Database

    Galád, Adrián

    2010-01-01

    Roč. 514, May (2010), A55/1-A55/10 ISSN 0004-6361 R&D Projects: GA ČR GA205/09/1107 Grant - others:Vega(SK) 2/0016/09 Institutional research plan: CEZ:AV0Z10030501 Keywords : minor planets * asteroids * photometric Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.410, year: 2010

  13. Improvement in the calibration time of absolute emission rate of radioisotopic neutron sources using vanadyl sulfate bath

    International Nuclear Information System (INIS)

    Khabaz, Rahim

    2012-01-01

    In this study, for calibration of emission rate of radioisotopic neutron sources, a suitable vanadium salt was proposed instead manganese sulfate because the shorter half-life of 52 V would facilitate faster neutron yield measurements to be made with a shorter delay time between subsequent measurements. Using Monte Carlo method, different correction factors of manganese and vanadyl sulfate baths were calculated and compared with each other. The results showed that for having an appropriate efficiency of VBS, high concentrations of solution must be used. - Highlights: ► The widely used method for measurement of emission rate of radioisotopic neutron sources is MBS. ► One of limitations of MBS is time required for activation to saturation and background measurement. ► The aim of this study is to evaluate a calibration method by VBS with about one-hour full-cycle time. ► The relative efficiency per neutron of VBS was just about half that obtained from MBS. ► The relative efficiency of VBS is compensated with increasing the concentration of solution.

  14. The absolute calibration of KOMPSAT-3 and 3A high spatial resolution satellites using radiometric tarps and MFRSR measurments

    Science.gov (United States)

    Yeom, J. M.

    2017-12-01

    Recently developed Korea Multi-Purpose Satellite-3A (KOMPSAT-3A), which is a continuation of the KOMPSAT-1, 2 and 3 earth observation satellite (EOS) programs from the Korea Aerospace Research Institute (KARI) was launched on March, 25 2015 on a Dnepr-1 launch vehicle from the Jasny Dombarovsky site in Russia. After launched, KARI performed in-orbit-test (IOT) including radiometric calibration for 6 months from 14 Apr. to 4 Sep. 2015. KOMPSAT-3A is equipped with two distinctive sensors; one is a high resolution multispectral optical sensor, namely the Advances Earth Image Sensor System-A (AEISS-A) and the other is the Scanner Infrared Imaging System (SIIS). In this study, we focused on the radiometric calibration of AEISS-A. The multispectral wavelengths of AEISS-A are covering three visible regions: blue (450 - 520 nm), green (520 - 600 nm), red (630 - 690 nm), one near infrared (760 - 900 nm) with a 2.0 m spatial resolution at nadir, whereas the panchromatic imagery (450 - 900 nm) has a 0.5 m resolution. Those are the same spectral response functions were same with KOMPSAT-3 multispectral and panchromatic bands but the spatial resolutions are improved. The main mission of KOMPSAT-3A is to develop for Geographical Information System (GIS) applications in environmental, agriculture, and oceanographic sciences, as well as natural hazard monitoring.

  15. On the use of mobile phones and wearable microphones for noise exposure measurements: Calibration and measurement accuracy

    Science.gov (United States)

    Dumoulin, Romain

    Despite the fact that noise-induced hearing loss remains the number one occupational disease in developed countries, individual noise exposure levels are still rarely known and infrequently tracked. Indeed, efforts to standardize noise exposure levels present disadvantages such as costly instrumentation and difficulties associated with on site implementation. Given their advanced technical capabilities and widespread daily usage, mobile phones could be used to measure noise levels and make noise monitoring more accessible. However, the use of mobile phones for measuring noise exposure is currently limited due to the lack of formal procedures for their calibration and challenges regarding the measurement procedure. Our research investigated the calibration of mobile phone-based solutions for measuring noise exposure using a mobile phone's built-in microphones and wearable external microphones. The proposed calibration approach integrated corrections that took into account microphone placement error. The corrections were of two types: frequency-dependent, using a digital filter and noise level-dependent, based on the difference between the C-weighted noise level minus A-weighted noise level of the noise measured by the phone. The electro-acoustical limitations and measurement calibration procedure of the mobile phone were investigated. The study also sought to quantify the effect of noise exposure characteristics on the accuracy of calibrated mobile phone measurements. Measurements were carried out in reverberant and semi-anechoic chambers with several mobiles phone units of the same model, two types of external devices (an earpiece and a headset with an in-line microphone) and an acoustical test fixture (ATF). The proposed calibration approach significantly improved the accuracy of the noise level measurements in diffuse and free fields, with better results in the diffuse field and with ATF positions causing little or no acoustic shadowing. Several sources of errors

  16. T2K off-axis near detector νμ flux measurement and absolute momentum scale calibration of the off-axis near detector tracker

    International Nuclear Information System (INIS)

    Blaszczyk, F.

    2011-09-01

    In this thesis we present the results from the ν μ energy spectrum measurement at T2K's near detector and T2K's near detector tracker absolute momentum scale calibration. First we review the main historical steps and the current state of the art of neutrino physics as well as the theoretical framework required to understand the thesis physics analyses presented later on. In particular we focus on the neutrino oscillation parametrization and the neutrino-matter interaction models. We then describe T2K, an off-axis long baseline neutrino oscillation experiment in Japan which consists of a muon neutrino beam sent from J-PARC to Super- Kamiokande, with a magnetized near detector located at 280 m from the neutrino production site. T2K's main goals are measuring the last unknown angle of the PMNS matrix θ 13 through the search of ν e appearance in the ν μ beam and measuring precisely the atmospheric parameters through muon neutrino disappearance. We briefly describe the detectors, in particular the near detector tracker and its performance. We then present the analyses tools, such as the reconstruction techniques used and how the neutrino charged current interaction events needed for the energy spectrum measurement are selected. The main goal of the thesis, the muon neutrino energy spectrum measurement done with the first T2K data is explained next. We give the motivations for such measurement, the results obtained with the first T2K data sample, and the different systematic errors studied. Finally, the absolute momentum scale calibration of T2K's near detector tractor, done through the reconstruction of the neutral kaon invariant mass, is explained. (author)

  17. Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat-spectral response

    Energy Technology Data Exchange (ETDEWEB)

    Troussel, Ph.; Villette, B.; Oudot, G.; Tassin, V. [CEA/DAM/DIF, Bruyères le Châtel, 91297 Arpajon (France); Emprin, B. [CEA/DAM/DIF, Bruyères le Châtel, 91297 Arpajon (France); Laboratoire Charles Fabry, Institut d’Optique, CNRS, University Paris-Sud, 2, Avenue Augustin Fresnel, RD128, 91127 Palaiseau Cedex (France); Bridou, F.; Delmotte, F. [Laboratoire Charles Fabry, Institut d’Optique, CNRS, University Paris-Sud, 2, Avenue Augustin Fresnel, RD128, 91127 Palaiseau Cedex (France); Krumrey, M. [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany)

    2014-01-15

    CEA implemented an absolutely calibrated broadband soft X-ray spectrometer called DMX on the Omega laser facility at the Laboratory for Laser Energetics (LLE) in 1999 to measure radiant power and spectral distribution of the radiation of the Au plasma. The DMX spectrometer is composed of 20 channels covering the spectral range from 50 eV to 20 keV. The channels for energies below 1.5 keV combine a mirror and a filter with a coaxial photo-emissive detector. For the channels above 5 keV the photoemissive detector is replaced by a conductive detector. The intermediate energy channels (1.5 keV < photon energy < 5 keV) use only a filter and a coaxial detector. A further improvement of DMX consists in flat-response X-ray channels for a precise absolute measurement of the photon flux in the photon energy range from 0.1 keV to 6 keV. Such channels are equipped with a filter, a Multilayer Mirror (MLM), and a coaxial detector. We present as an example the development of channel for the gold M emission lines in the photon energy range from 2 keV to 4 keV which has been successfully used on the OMEGA laser facility. The results of the radiant power measurements with the new MLM channel and with the usual channel composed of a thin titanium filter and a coaxial detector (without mirror) are compared. All elements of the channel have been calibrated in the laboratory of the Physikalisch-Technische Bundesanstalt, Germany's National Metrology Institute, at the synchrotron radiation facility BESSY II in Berlin using dedicated well established and validated methods.

  18. Development of highly efficient proton recoil counter telescope for absolute measurement of neutron fluences in quasi-monoenergetic neutron calibration fields of high energy

    International Nuclear Information System (INIS)

    Shikaze, Yoshiaki; Tanimura, Yoshihiko; Saegusa, Jun; Tsutsumi, Masahiro

    2010-01-01

    Precise calibration of monitors and dosimeters for use with high energy neutrons necessitates reliable and accurate neutron fluences being evaluated with use of a reference point. A highly efficient Proton Recoil counter Telescope (PRT) to make absolute measurements with use of a reference point was developed to evaluate neutron fluences in quasi-monoenergetic neutron fields. The relatively large design of the PRT componentry and relatively thick, approximately 2 mm, polyethylene converter contributed to high detection efficiency at the reference point over a large irradiation area at a long distance from the target. The polyethylene converter thickness was adjusted to maintain the same carbon density per unit area as the graphite converter for easy background subtraction. The high detection efficiency and thickness adjustment resulted in efficient absolute measurements being made of the neutron fluences of sufficient statistical precision over a short period of time. The neutron detection efficiencies of the PRT were evaluated using MCNPX code at 2.61x10 -6 , 2.16x10 -6 and 1.14x10 -6 for the respective neutron peak energies of 45, 60 and 75 MeV. The neutron fluences were determined to have been evaluated at an uncertainty of within 6.5% using analysis of measured data and the detection efficiencies. The PRT was also designed so as to be capable of simultaneously obtaining TOF data. The TOF data also increased the reliability of neutron fluence measurements and provided useful information for use in interpreting the source of proton events.

  19. RELATIVE AND ABSOLUTE CALIBRATION OF A MULTIHEAD CAMERA SYSTEM WITH OBLIQUE AND NADIR LOOKING CAMERAS FOR A UAS

    Directory of Open Access Journals (Sweden)

    F. Niemeyer

    2013-08-01

    Full Text Available Numerous unmanned aerial systems (UAS are currently flooding the market. For the most diverse applications UAVs are special designed and used. Micro and mini UAS (maximum take-off weight up to 5 kg are of particular interest, because legal restrictions are still manageable but also the payload capacities are sufficient for many imaging sensors. Currently a camera system with four oblique and one nadir looking cameras is under development at the Chair for Geodesy and Geoinformatics. The so-called "Four Vision" camera system was successfully built and tested in the air. A MD4-1000 UAS from microdrones is used as a carrier system. Light weight industrial cameras are used and controlled by a central computer. For further photogrammetric image processing, each individual camera, as well as all the cameras together have to be calibrated. This paper focuses on the determination of the relative orientation between the cameras with the „Australis“ software and will give an overview of the results and experiences of test flights.

  20. Maintaining the accuracy of the (60)Co calibration service at the ARPANSA post source replacement in 2010.

    Science.gov (United States)

    Oliver, Chris; Butler, Duncan; Webb, David; Wright, Tracy; Lye, Jessica; Ramanathan, Ganesan; Harty, Peter; Takau, Viliami

    2015-06-01

    The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) maintains a (60)Co teletherapy source primarily for the calibration of therapy dosemeters. The source and encapsulating head were replaced in early 2010 with an Eldorado 78 head and new (60)Co source. In this article we present the results of ongoing accuracy and stability measurements since the replacement. A number of formal and informal indirect comparisons have been carried out with laboratories holding primary and secondary standards for (60)Co. ARPANSA chambers have also been calibrated at international primary standard laboratories allowing comparison of calibration coefficients and thus (60)Co absorbed dose standards. (60)Co calibration coefficients supplied by manufacturers of chambers were compared to those measured at the ARPANSA when this calibration was traceable to a primary standard. ARPANSA also participates in an annual international mailed dosimetry audit conducted by the International Atomic Energy Agency. The results thus far demonstrate that the absorbed doses to water delivered by the new ARPANSA (60)Co source are consistent with international doses within the stated uncertainties.

  1. INVESTIGATION OF PHOTOTRIANGULATION ACCURACY WITH USING OF VARIOUS TECHNIQUES LABORATORY AND FIELD CALIBRATION

    Directory of Open Access Journals (Sweden)

    A. G. Chibunichev

    2016-10-01

    Full Text Available Nowadays, aerial survey technology using aerial systems based on unmanned aerial vehicles (UAVs becomes more popular. UAVs physically can not carry professional aerocameras. Consumer digital cameras are used instead. Such cameras usually have rolling, lamellar or global shutter. Quite often manufacturers and users of such aerial systems do not use camera calibration. In this case self-calibration techniques are used. However such approach is not confirmed by extensive theoretical and practical research. In this paper we compare results of phototriangulation based on laboratory, test-field or self-calibration. For investigations we use Zaoksky test area as an experimental field provided dense network of target and natural control points. Racurs PHOTOMOD and Agisoft PhotoScan software were used in evaluation. The results of investigations, conclusions and practical recommendations are presented in this article.

  2. Absolute metrology for space interferometers

    Science.gov (United States)

    Salvadé, Yves; Courteville, Alain; Dändliker, René

    2017-11-01

    The crucial issue of space-based interferometers is the laser interferometric metrology systems to monitor with very high accuracy optical path differences. Although classical high-resolution laser interferometers using a single wavelength are well developed, this type of incremental interferometer has a severe drawback: any interruption of the interferometer signal results in the loss of the zero reference, which requires a new calibration, starting at zero optical path difference. We propose in this paper an absolute metrology system based on multiplewavelength interferometry.

  3. Radiometric and Polarimetric Accuracy Assessment and Calibration of the Hyper-Angular Rainbow Polarimeter (HARP) Instrument

    Science.gov (United States)

    McBride, B.; Martins, J. V.; Fernandez Borda, R. A.; Barbosa, H. M.

    2017-12-01

    The Laboratory for Aerosols, Clouds, and Optics (LACO) at the University of Maryland, Baltimore County (UMBC) present a novel, wide FOV, hyper-angular imaging polarimeter for the microphysical sampling of clouds and aerosols from aircraft and space. The instrument, the Hyper-Angular Rainbow Polarimeter (HARP), is a precursor to the multi-angle imaging polarimeter solicited by the upcoming NASA Aerosols, Clouds, and Ecosystems (ACE) mission. HARP currently operates in two forms: a spaceborne CubeSat slated for a January 2018 launch to the ISS orbit, and an identical aircraft platform that participated in the Lake Michigan Ozone Study (LMOS) and Aerosol Characterization from Polarimeter and Lidar (ACEPOL) NASA campaigns in 2017. To ensure and validate the instrument's ability to produce high quality Level 2 cloud and aerosol microphysical products, a comprehensive calibration scheme that accounts for flatfielding, radiometry, and all optical interference processes that contribute to the retrieval of Stokes parameters I, Q, and U, is applied across the entirety of HARP's 114° FOV. We present an innovative calibration algorithm that convolves incident polarization from a linear polarization state generator with intensity information observed at three distinct linear polarizations. The retrieved results are pixel-level, modified Mueller matrices that characterize the entire HARP optical assembly, without the need to characterize every individual element or perform ellipsometric studies. Here we show results from several pre- and post- LMOS campaign radiometric calibrations at NASA GSFC and polarimetric calibration using a "polarization dome" that allows for full-FOV characterization of Stokes parameters I, Q, and U. The polarization calibration is verified by passing unpolarized light through partially-polarized, tilted glass plates with well-characterized degree of linear polarization (DoLP). We apply this calibration to a stratocumulous cloud deck case observed

  4. A Multilaboratory Comparison of Calibration Accuracy and the Performance of External References in Analytical Ultracentrifugation

    DEFF Research Database (Denmark)

    Zhao, Huaying; Ghirlando, Rodolfo; Alfonso, Carlos

    2015-01-01

    coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time...... radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic...

  5. Improving LIGO calibration accuracy by tracking and compensating for slow temporal variations

    International Nuclear Information System (INIS)

    Tuyenbayev, D; Karki, S; Goetz, E; Izumi, K; Kissel, J S; Mendell, G; Savage, R L; Betzwieser, J; Kandhasamy, S; Cahillane, C; Weinstein, A J; Wade, M

    2017-01-01

    Calibration of the second-generation LIGO interferometric gravitational-wave detectors employs a method that uses injected periodic modulations to track and compensate for slow temporal variations in the differential length response of the instruments. These detectors utilize feedback control loops to maintain resonance conditions by suppressing differential arm length variations. We describe how the sensing and actuation functions of these servo loops are parameterized and how the slow variations in these parameters are quantified using the injected modulations. We report the results of applying this method to the LIGO detectors and show that it significantly reduces systematic errors in their calibrated outputs. (paper)

  6. Accuracy, reproducibility, and uncertainty analysis of thyroid-probe-based activity measurements for determination of dose calibrator settings.

    Science.gov (United States)

    Esquinas, Pedro L; Tanguay, Jesse; Gonzalez, Marjorie; Vuckovic, Milan; Rodríguez-Rodríguez, Cristina; Häfeli, Urs O; Celler, Anna

    2016-12-01

    In the nuclear medicine department, the activity of radiopharmaceuticals is measured using dose calibrators (DCs) prior to patient injection. The DC consists of an ionization chamber that measures current generated by ionizing radiation (emitted from the radiotracer). In order to obtain an activity reading, the current is converted into units of activity by applying an appropriate calibration factor (also referred to as DC dial setting). Accurate determination of DC dial settings is crucial to ensure that patients receive the appropriate dose in diagnostic scans or radionuclide therapies. The goals of this study were (1) to describe a practical method to experimentally determine dose calibrator settings using a thyroid-probe (TP) and (2) to investigate the accuracy, reproducibility, and uncertainties of the method. As an illustration, the TP method was applied to determine 188 Re dial settings for two dose calibrator models: Atomlab 100plus and Capintec CRC-55tR. Using the TP to determine dose calibrator settings involved three measurements. First, the energy-dependent efficiency of the TP was determined from energy spectra measurements of two calibration sources ( 152 Eu and 22 Na). Second, the gamma emissions from the investigated isotope ( 188 Re) were measured using the TP and its activity was determined using γ-ray spectroscopy methods. Ambient background, scatter, and source-geometry corrections were applied during the efficiency and activity determination steps. Third, the TP-based 188 Re activity was used to determine the dose calibrator settings following the calibration curve method [B. E. Zimmerman et al., J. Nucl. Med. 40, 1508-1516 (1999)]. The interobserver reproducibility of TP measurements was determined by the coefficient of variation (COV) and uncertainties associated to each step of the measuring process were estimated. The accuracy of activity measurements using the proposed method was evaluated by comparing the TP activity estimates of 99m Tc

  7. Frequency-comb-assisted absolute calibration and linestrength of H12C13CH ro-vibrational transitions in the 2ν3 band

    Science.gov (United States)

    Di Sarno, Valentina; De Natale, Paolo; Tasseva, Jordanka; Santamaria, Luigi; Cané, Elisabetta; Tamassia, Filippo; Maddaloni, Pasquale

    2018-02-01

    We report on a precision spectroscopic study of room-temperature H12C13CH in the 6463-6520 cm-1 range, using a continuous-wave diode laser phase-locked to a near-infrared optical frequency comb synthesizer stabilized, in turn, against a GPS-disciplined rubidium clock. By tuning the comb repetition frequency, several ro-vibrational transitions in the P and R branches of the 2ν3 overtone band are recorded. Accuracy levels as low as 100 kHz, 5 ·10-10 in fractional terms, are obtained in the determination of absolute line-center frequencies. In addition, line intensities are measured for the first time, with a best fractional uncertainty of 1%, and used to retrieve the purely vibrational transition dipole moment in conjunction with the first-order Herman-Wallis factor. Finally, the pressure broadening coefficients γself are also derived for the studied transitions.

  8. Calibration procedures for improved accuracy of wind turbine blade load measurement

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, J.Aa. [Aeronautical Research Inst. of Sweden, Bromma (Sweden); Johansson, Hjalmar [Teknikgruppen AB, Sollentuna (Sweden)

    1996-12-01

    External loads acting on wind turbine blades are mainly transferred via the hub to the rest of the structure. It is therefore a normal approach to measure the loads acting on the turbine by load measurements in the blade roots. The load measurement is often accomplished by measurements of strain on the surface of the blade or the hub. The strain signals are converted to loads by applying calibration factors to the measurements. This paper deals with difficulties associated with load measurements on two different wind turbines; one with strain gauges applied to a steel hub where a linear stress-load relationship is expected and the other with strain gauges applied to the GFRP blade close to the bearings where strong non-linearity`s and temperature effects are expected. This paper suggests calibration methods to overcome these problems. 2 refs, 11 figs

  9. The final power calibration of the IPEN/MB-01 nuclear reactor for various configurations obtained from the measurements of the absolute average neutron flux

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Alexandre Fonseca Povoa da, E-mail: alexandre.povoa@mar.mil.br [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil); Bitelli, Ulysses d' Utra; Mura, Luiz Ernesto Credidio; Lima, Ana Cecilia de Souza; Betti, Flavio; Santos, Diogo Feliciano dos, E-mail: ubitelli@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    The use of neutron activation foils is a widely spread technique applied to obtain nuclear parameters then comparing the results with those calculated using specific methodologies and available nuclear data. By irradiation of activation foils and subsequent measurement of its induced activity, it is possible to determine the neutron flux at the position of irradiation. The power level during operation of the reactor is a parameter which is directly proportional to the average neutron flux throughout the core. The objective of this work is to gather data from irradiation of gold foils symmetrically placed along a cylindrically configured core which presents only a small excess reactivity in order to derive the power generated throughout the spatial thermal and epithermal neutron flux distribution over the core of the IPEN/MB-01 Nuclear Reactor, eventually lending to a proper calibration of its nuclear channels. The foils are fixed in a Lucite plate then irradiated with and without cadmium sheaths so as to obtain the absolute thermal and epithermal neutron flux. The correlation between the average power neutron flux resulting from the gold foils irradiation, and the average power digitally indicated by the nuclear channel number 6, allows for the calibration of the nuclear channels of the reactor. The reactor power level obtained by thermal neutron flux mapping was (74.65 ± 2.45) watts to a mean counting per seconds of 37881 cps to nuclear channel number 10 a pulse detector, and 0.719.10{sup -5} ampere to nuclear linear channel number 6 (a non-compensated ionization chamber). (author)

  10. Determination of Delta m(d) and absolute calibration of flavor taggers for the Delta m(s) analysis, in fully reconstructed decays at the CDF experiment

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Jonatan Piedra [University of Cantabria, (Spain). Inst. of Physics

    2005-04-21

    The new trigger processor, the Silicon Vertex Tracking (SVT), has dramatically improved the B physics capabilities of the upgraded CDF II Detector; for the first time in a hadron collider, the SVT has enabled the access to non-lepton-triggered B meson decays. Within the new available range of decay modes, the B$0\\atop{s}$ → D$-\\atop{s}$π+ signature is of paramount importance in the measurement of the Δms mixing frequency. The analysis reported here is a step towards the measurement of this frequency; two where our goals: carrying out the absolute calibration of the opposite side flavor taggers, used in the Δms measurement; and measuring the B$0\\atop{d}$ mixing frequency in a B → Dπ sample, establishing the feasibility of the mixing measurement in this sample whose decay-length is strongly biased by the selective SVT trigger. We analyze a total integrated luminosity of 355 pb-1 collected with the CDF II Detector. By triggering on muons, using the conventional di-muon trigger; or displaced tracks, using the SVT trigger, we gather a sample rich in bottom and charm mesons.

  11. Accuracy of Dose Calibrators for 68Ga PET Imaging: Unexpected Findings in a Multicenter Clinical Pretrial Assessment.

    Science.gov (United States)

    Bailey, Dale L; Hofman, Michael S; Forwood, Nicholas J; O'Keefe, Graeme J; Scott, Andrew M; van Wyngaardt, Winifred M; Howe, Bonnie; Kovacev, Olga; Francis, Roslyn J

    2018-04-01

    We report the discovery of a systematic miscalibration during the work-up process for site validation of a multicenter clinical PET imaging trial using 68 Ga, which manifested as a consistent and reproducible underestimation in the quantitative accuracy (assessed by SUV) of a range of PET systems from different manufacturers at several different facilities around Australia. Methods: Sites were asked to follow a strict preparation protocol to create a radioactive phantom with 68 Ga to be imaged using a standard clinical protocol before commencing imaging in the trial. All sites had routinely used 68 Ga for clinical PET imaging for many years. The reconstructed image data were transferred to an imaging core laboratory for analysis, along with information about ancillary equipment such as the radionuclide dose calibrator. Fourteen PET systems were assessed from 10 nuclear medicine facilities in Australia, with the aim for each PET system being to produce images within 5% of the true SUV. Results: At initial testing, 10 of the 14 PET systems underestimated the SUV by 15% on average (range, 13%-23%). Multiple PET systems at one site, from two different manufacturers, were all similarly affected, suggesting a common cause. We eventually identified an incorrect factory-shipped dose calibrator setting from a single manufacturer as being the cause. The calibrator setting for 68 Ga was subsequently adjusted by the users so that the reconstructed images produced accurate values. Conclusion: PET imaging involves a chain of measurements and calibrations to produce accurate quantitative performance. Testing of the entire chain is simple, however, and should form part of any quality assurance program or prequalifying site assessment before commencing a quantitative imaging trial or clinical imaging. © 2018 by the Society of Nuclear Medicine and Molecular Imaging.

  12. Life History Traits and Niche Instability Impact Accuracy and Temporal Transferability for Historically Calibrated Distribution Models of North American Birds.

    Science.gov (United States)

    Wogan, Guinevere O U

    2016-01-01

    A primary assumption of environmental niche models (ENMs) is that models are both accurate and transferable across geography or time; however, recent work has shown that models may be accurate but not highly transferable. While some of this is due to modeling technique, individual species ecologies may also underlie this phenomenon. Life history traits certainly influence the accuracy of predictive ENMs, but their impact on model transferability is less understood. This study investigated how life history traits influence the predictive accuracy and transferability of ENMs using historically calibrated models for birds. In this study I used historical occurrence and climate data (1950-1990s) to build models for a sample of birds, and then projected them forward to the 'future' (1960-1990s). The models were then validated against models generated from occurrence data at that 'future' time. Internal and external validation metrics, as well as metrics assessing transferability, and Generalized Linear Models were used to identify life history traits that were significant predictors of accuracy and transferability. This study found that the predictive ability of ENMs differs with regard to life history characteristics such as range, migration, and habitat, and that the rarity versus commonness of a species affects the predicted stability and overlap and hence the transferability of projected models. Projected ENMs with both high accuracy and transferability scores, still sometimes suffered from over- or under- predicted species ranges. Life history traits certainly influenced the accuracy of predictive ENMs for birds, but while aspects of geographic range impact model transferability, the mechanisms underlying this are less understood.

  13. Calibration aspects of a polarimetric phased array airborne SAR [L'Etalonnage d'un SAR aeroporte polarimetrique a antenna active}

    NARCIS (Netherlands)

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

    1994-01-01

    Purpose of calibration is to get an accurate and Precise instrument. The precision of the instrument can be determined using internal calibration, while the accuracy is denoted with absolute calibration. With internal calibration only the instrument is considered. Because of practical considerations

  14. A new reliable, transposable and cost-effective assay for absolute quantification of total plasmatic bevacizumab by LC-MS/MS in human plasma comparing two internal standard calibration approaches.

    Science.gov (United States)

    Legeron, Rachel; Xuereb, Fabien; Chaignepain, Stephane; Gadeau, Alain-Pierre; Claverol, Stephane; Dupuy, Jean-William; Djabarouti, Sarah; Couffinhal, Thierry; Schmitter, Jean-Marie; Breilh, Dominique

    2017-12-01

    The quantification of monoclonal antibodies (mAbs) such as bevacizumab, a recombinant humanized immunoglobulin G1 (hIgG1), in biological fluids, is an essential prerequisite to any pharmacokinetic preclinical and clinical study. To date, reference techniques used to quantify mAbs rely on enzyme-linked immunosorbent assay (ELISA) lacking specificity. Furthermore, the commercially available ELISA kit to quantify bevacizumab in human plasma only assesses the free fraction of the drug. However, the conditions of storage and analysis of plasma samples could alter the physiological equilibrium between the free, bound and partially bound forms of bevacizumab and this could result in over- or underestimation of drug concentration. We developed a new assay for absolute quantification of total fraction of bevacizumab by liquid chromatography tandem mass spectrometry (LC-MS/MS) basing identification and quantification of bevacizumab on two specific peptides. In this report we compare our assay with two internal standard (IS) calibration approaches: one using a different human mAb (Trastuzumab) and the other using a stable isotope labeled specific peptide. After enrichment by affinity chromatography on protein A and concentration by ultrafiltration, human plasma samples were proteolyzed by trypsin. Linearity was established from 12.5 to 500μg/mL with an interday accuracy ranging from 101.7 to 110.6% and precision from 7.0% to 9.9%. This study demonstrates the importance of the choice of the IS in quantifying bevacizumab in human plasma and highlights the difficulty of reaching a reliable proteolysis with a sufficient recovery. We developed a reliable and cost-effective LC-MS/MS method to quantify total plasmatic fraction of bevacizumab in human plasma. Through our development we proposed a generic methodology easily transposable to quantify all IgG1 subclass very useful for clinical pharmacokinetics studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Electron cyclotron emission spectra in X- and O-mode polarisation at JET: Martin-Puplett interferometer, absolute calibration, revised uncertainties, inboard/outboard temperature profile, and wall properties.

    Science.gov (United States)

    Schmuck, S; Fessey, J; Boom, J E; Meneses, L; Abreu, P; Belonohy, E; Lupelli, I

    2016-09-01

    At the tokamak Joint European Torus (JET), the electron cyclotron emission spectra in O-mode and X-mode polarisations are diagnosed simultaneous in absolute terms for several harmonics with two Martin-Puplett interferometers. From the second harmonic range in X-mode polarisation, the electron temperature profile can be deduced for the outboard side (low magnetic field strength) of JET but only for some parts of the inboard side (high magnetic field strength). This spatial restriction can be bypassed, if a cutoff is not present inside the plasma for O-mode waves in the first harmonic range. Then, from this spectral domain, the profile on the entire inboard side is accessible. The profile determination relies on the new absolute and independent calibration for both interferometers. During the calibration procedure, the antenna pattern was investigated as well, and, potentially, an increase in the diagnostic responsivity of about 5% was found for the domain 100-300 GHz. This increase and other uncertainty sources are taken into account in the thorough revision of the uncertainty for the diagnostic absolute calibration. The uncertainty deduced and the convolution inherent for Fourier spectroscopy diagnostics have implications for the temperature profile inferred. Having probed the electron cyclotron emission spectra in orthogonal polarisation directions for the first harmonic range, a condition is derived for the reflection and polarisation-scrambling coefficients of the first wall on the outboard side of JET.

  16. The Quantitative Relationship Between ISO 15197 Accuracy Criteria and Mean Absolute Relative Difference (MARD) in the Evaluation of Analytical Performance of Self-Monitoring of Blood Glucose (SMBG) Systems.

    Science.gov (United States)

    Pardo, Scott; Simmons, David A

    2016-09-01

    The relationship between International Organization for Standardization (ISO) accuracy criteria and mean absolute relative difference (MARD), 2 methods for assessing the accuracy of blood glucose meters, is complex. While lower MARD values are generally better than higher MARD values, it is not possible to define a particular MARD value that ensures a blood glucose meter will satisfy the ISO accuracy criteria. The MARD value that ensures passing the ISO accuracy test can be described only as a probabilistic range. In this work, a Bayesian model is presented to represent the relationship between ISO accuracy criteria and MARD. Under the assumptions made in this work, there is nearly a 100% chance of satisfying ISO 15197:2013 accuracy requirements if the MARD value is between 3.25% and 5.25%. © 2016 Diabetes Technology Society.

  17. The Effects of Strategy Training and an Extrinsic Incentive on Fourth- and Fifth-Grade Students' Performance, Confidence, and Calibration Accuracy

    Science.gov (United States)

    Gutierrez de Blume, Antonio P.

    2017-01-01

    This study investigated the influence of strategy training instruction and an extrinsic incentive on American fourth- and fifth-grade students' (N = 35) performance, confidence in performance, and calibration accuracy. Using an experimental design, children were randomized to either an experimental group (strategy training and an extrinsic…

  18. High accuracy calibration of a dynamic vapor sorption instrument and determination of the equilibrium humidities using single salts

    DEFF Research Database (Denmark)

    Rörig-Dalgaard, Inge; Svensson, Staffan

    2016-01-01

    We present a procedure for accurately calibrating a dynamic vapor sorption (DVS) instrument using single salts. The procedure accounts for and tailors distinct calibration tests according to the fundamental properties of each salt. Especially relevant properties influencing the calibration...... are the heat of solution, heat of condensation, and the kinetics connected to the salt phase transition, as these influence the microclimate surrounding the salts during calibration. All these issues were dealt with to obtain precise calibration results. The DVS instrument comprises two control modes......-known equilibrium RH of each salt solution, the presented method’s results are both accurate with significant agreement and precise with small variation....

  19. INTRODUCING NOVEL GENERATION OF HIGH ACCURACY CAMERA OPTICAL-TESTING AND CALIBRATION TEST-STANDS FEASIBLE FOR SERIES PRODUCTION OF CAMERAS

    Directory of Open Access Journals (Sweden)

    M. Nekouei Shahraki

    2015-12-01

    Full Text Available The recent advances in the field of computer-vision have opened the doors of many opportunities for taking advantage of these techniques and technologies in many fields and applications. Having a high demand for these systems in today and future vehicles implies a high production volume of video cameras. The above criterions imply that it is critical to design test systems which deliver fast and accurate calibration and optical-testing capabilities. In this paper we introduce new generation of test-stands delivering high calibration quality in single-shot calibration of fisheye surround-view cameras. This incorporates important geometric features from bundle-block calibration, delivers very high (sub-pixel calibration accuracy, makes possible a very fast calibration procedure (few seconds, and realizes autonomous calibration via machines. We have used the geometrical shape of a Spherical Helix (Type: 3D Spherical Spiral with special geometrical characteristics, having a uniform radius which corresponds to the uniform motion. This geometrical feature was mechanically realized using three dimensional truncated icosahedrons which practically allow the implementation of a spherical helix on multiple surfaces. Furthermore the test-stand enables us to perform many other important optical tests such as stray-light testing, enabling us to evaluate the certain qualities of the camera optical module.

  20. Accuracy of Visante and Zeiss-Humphrey Optical Coherence Tomographers and their cross calibration with optical pachymetry and physical references

    Directory of Open Access Journals (Sweden)

    Jyotsna Maram

    2011-10-01

    Conclusions: Using references lenses with refractive index of the cornea (1.376 allows rapid and simple calibration and cross calibration of instruments for measuring the corneal thickness. The Visante and OCT II do not produce measurements that are equal to physical references with refractive index equal to the human cornea.

  1. 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.

  2. Accuracy and calibration of integrated radiation output indicators in diagnostic radiology: A report of the AAPM Imaging Physics Committee Task Group 190

    International Nuclear Information System (INIS)

    Lin, Pei-Jan P.; Schueler, Beth A.; Balter, Stephen; Strauss, Keith J.; Wunderle, Kevin A.; LaFrance, M. Terry; Kim, Don-Soo; Behrman, Richard H.; Shepard, S. Jeff; Bercha, Ishtiaq H.

    2015-01-01

    Due to the proliferation of disciplines employing fluoroscopy as their primary imaging tool and the prolonged extensive use of fluoroscopy in interventional and cardiovascular angiography procedures, “dose-area-product” (DAP) meters were installed to monitor and record the radiation dose delivered to patients. In some cases, the radiation dose or the output value is calculated, rather than measured, using the pertinent radiological parameters and geometrical information. The AAPM Task Group 190 (TG-190) was established to evaluate the accuracy of the DAP meter in 2008. Since then, the term “DAP-meter” has been revised to air kerma-area product (KAP) meter. The charge of TG 190 (Accuracy and Calibration of Integrated Radiation Output Indicators in Diagnostic Radiology) has also been realigned to investigate the “Accuracy and Calibration of Integrated Radiation Output Indicators” which is reflected in the title of the task group, to include situations where the KAP may be acquired with or without the presence of a physical “meter.” To accomplish this goal, validation test protocols were developed to compare the displayed radiation output value to an external measurement. These test protocols were applied to a number of clinical systems to collect information on the accuracy of dose display values in the field

  3. Accuracy and calibration of integrated radiation output indicators in diagnostic radiology: A report of the AAPM Imaging Physics Committee Task Group 190

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Pei-Jan P., E-mail: Pei-Jan.Lin@vcuhealth.org [Virginia Commonwealth University Medical Center, Richmond, Virginia 23298 (United States); Schueler, Beth A. [Mayo Clinic, Rochester, Minnesota 55905 (United States); Balter, Stephen [Columbia University Medical Center, New York, New York 10032 (United States); Strauss, Keith J. [Children’s Hospital Medical Center, Cincinnati, Ohio 45229 (United States); Wunderle, Kevin A. [Cleveland Clinic Foundation, Cleveland, Ohio 44195 (United States); LaFrance, M. Terry [Baystate Health Systems, Inc., Springfield, Massachusetts 01199 (United States); Kim, Don-Soo [Children’s Hospital Boston, Boston, Massachusetts 02115 (United States); Behrman, Richard H. [Boston University Medical Center, Boston, Massachusetts 02118 (United States); Shepard, S. Jeff [University of Texas MD Anderson Cancer Center, Houston, Texas 77096 (United States); Bercha, Ishtiaq H. [Children’s Hospital Colorado, Aurora, Colorado 80045 (United States)

    2015-12-15

    Due to the proliferation of disciplines employing fluoroscopy as their primary imaging tool and the prolonged extensive use of fluoroscopy in interventional and cardiovascular angiography procedures, “dose-area-product” (DAP) meters were installed to monitor and record the radiation dose delivered to patients. In some cases, the radiation dose or the output value is calculated, rather than measured, using the pertinent radiological parameters and geometrical information. The AAPM Task Group 190 (TG-190) was established to evaluate the accuracy of the DAP meter in 2008. Since then, the term “DAP-meter” has been revised to air kerma-area product (KAP) meter. The charge of TG 190 (Accuracy and Calibration of Integrated Radiation Output Indicators in Diagnostic Radiology) has also been realigned to investigate the “Accuracy and Calibration of Integrated Radiation Output Indicators” which is reflected in the title of the task group, to include situations where the KAP may be acquired with or without the presence of a physical “meter.” To accomplish this goal, validation test protocols were developed to compare the displayed radiation output value to an external measurement. These test protocols were applied to a number of clinical systems to collect information on the accuracy of dose display values in the field.

  4. Accuracy and calibration of integrated radiation output indicators in diagnostic radiology: A report of the AAPM Imaging Physics Committee Task Group 190.

    Science.gov (United States)

    Lin, Pei-Jan P; Schueler, Beth A; Balter, Stephen; Strauss, Keith J; Wunderle, Kevin A; LaFrance, M Terry; Kim, Don-Soo; Behrman, Richard H; Shepard, S Jeff; Bercha, Ishtiaq H

    2015-12-01

    Due to the proliferation of disciplines employing fluoroscopy as their primary imaging tool and the prolonged extensive use of fluoroscopy in interventional and cardiovascular angiography procedures, "dose-area-product" (DAP) meters were installed to monitor and record the radiation dose delivered to patients. In some cases, the radiation dose or the output value is calculated, rather than measured, using the pertinent radiological parameters and geometrical information. The AAPM Task Group 190 (TG-190) was established to evaluate the accuracy of the DAP meter in 2008. Since then, the term "DAP-meter" has been revised to air kerma-area product (KAP) meter. The charge of TG 190 (Accuracy and Calibration of Integrated Radiation Output Indicators in Diagnostic Radiology) has also been realigned to investigate the "Accuracy and Calibration of Integrated Radiation Output Indicators" which is reflected in the title of the task group, to include situations where the KAP may be acquired with or without the presence of a physical "meter." To accomplish this goal, validation test protocols were developed to compare the displayed radiation output value to an external measurement. These test protocols were applied to a number of clinical systems to collect information on the accuracy of dose display values in the field.

  5. Absolute calibration of imaging plate detectors for electron kinetic energies between 150 keV and 1.75 MeV

    Czech Academy of Sciences Publication Activity Database

    Singh, Sushil K.; Slavíček, T.; Hodak, R.; Versaci, Roberto; Pridal, P.; Kumar, D.

    2017-01-01

    Roč. 88, č. 7 (2017), 1-4, č. článku 075105. ISSN 0034-6748 R&D Projects: GA MŠk EF15_008/0000162; GA MŠk LQ1606 Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:68378271 Keywords : calibration * elektron Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 1.515, year: 2016

  6. Self consistently calibrated photopyroelectric calorimeter for the high resolution simultaneous absolute measurement of the specific heat and of the thermal conductivity

    Directory of Open Access Journals (Sweden)

    U. Zammit

    2012-03-01

    Full Text Available High temperature resolution study of the specific heat and of the thermal conductivity over the smecticA-nematic and nematic-isotropic phase transitions in octylcynobephenyl liquid crystal using a new photopyroelectric calorimetry configuration are reported, where, unlike previously adopted ones, no calibration is required other than the procedure used during the actual measurement. This makes photopyroelectric calorimetry suitable for “absolute” measurements of the thermal parameters like most other existing conventional calorimetric techniques where, however, the thermal conductivity cannot be measured.

  7. Prism-pair interferometry by homodyne interferometers with a common light source for high-accuracy measurement of the absolute refractive index of glasses.

    Science.gov (United States)

    Hori, Yasuaki; Hirai, Akiko; Minoshima, Kaoru

    2011-03-10

    A prism-pair interferometer comprising two homodyne interferometers with a common light source was developed for high-precision measurements of the refractive index of optical glasses with an uncertainty of the order of 10(-6). The two interferometers measure changes in the optical path length in the glass sample and in air, respectively. Uncertainties in the absolute wavelength of the common light source are cancelled out by calculating a ratio between the results from the interferometers. Uncertainties in phase measurement are suppressed by a quadrature detection system. The combined standard uncertainty of the developed system is evaluated as 1.1×10(-6).

  8. Precision and accuracy control of dose calibrator: CAPINTEC CRC 12 in laboratory for radiopharmacy of Nuclear Medicine Institute of Sucre, Bolivia

    International Nuclear Information System (INIS)

    Huanca Sardinas, E; Castro Sacci, O; Torrez Cabero, M; Vasquez Ibanez, M.R; Zambrana Zelada, AJ.

    2013-01-01

    The dose calibrator is one of the indispensable tools in radiopharmacy laboratories of a nuclear medicine department also is mandated to provide accurate readings. A very high doses produce unnecessary radiation exposure to the patient or a very low dose, prolong the acquisition time of the studies affecting the quality of the image. In the present work we did a retrospective analysis of the results of quality checks performed at precision accuracy of the Gauge CRC12 CAPINTEC dose calibrator over a period of 16 years, using sealed certified sources with low power, medium and high: Ba 133 , Cs 137 , Co 60 and Co 57 . The results showed that the lowest standard deviation value was 0.17 for Ba133, relative to Co 57 of 2.97 in the control of accuracy. Accuracy over control values were also lower standard deviation for Ba 133 1.00, relative to Co 57 10.06. Being stated that the CRC12 CAPINTEC activimeter reliability is acceptable during the reporting period and under the conditions indicated. Therefore, we continue to make these quality control procedures and the professional must feel confident that the measurements obtained with it are reliable

  9. A Software Module for High-Accuracy Calibration of Rings and Cylinders on CMM using Multi-Orientation Techniques (Multi-Step and Reversal methods)

    DEFF Research Database (Denmark)

    Tosello, Guido; De Chiffre, Leonardo

    . The Centre for Geometrical Metrology (CGM) at the Technical University of Denmark takes care of free form measurements, in collaboration with DIMEG, University of Padova, Italy. The present report describes a software module, ROUNDCAL, to be used for high-accuracy calibration of rings and cylinders....... The purpose of the software is to calculate the form error and the least square circle of rings and cylinders by mean of average of pontwise measuring results becoming from so-called multi-orientation techniques (both reversal and multi-step methods) in order to eliminate systematic errors of CMM ....

  10. Absolute Summ

    Science.gov (United States)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  11. Absolute dimensions of eclipsing binaries. XXVIII. BK Pegasi and other F-type binaries: Prospects for calibration of convective core overshoot

    Science.gov (United States)

    Clausen, J. V.; Frandsen, S.; Bruntt, H.; Olsen, E. H.; Helt, B. E.; Gregersen, K.; Juncher, D.; Krogstrup, P.

    2010-06-01

    Context. Double-lined, detached eclipsing binaries are our main source for accurate stellar masses and radii. In this paper we focus on the 1.15-1.70 M⊙ interval where convective core overshoot is gradually ramped up in theoretical evolutionary models. Aims: We aim to determine absolute dimensions and abundances for the F-type detached eclipsing binary BK Peg, and to perform a detailed comparison with results from recent stellar evolutionary models, including a sample of previously studied systems with accurate parameters. Methods: uvby light curves and uvbyβ standard photometry were obtained with the Strömgren Automatic Telescope, ESO, La Silla, and high-resolution spectra were acquired with the FIES spectrograph at the Nordic Optical Telescope, La Palma. Results: The 5 fd 49 period orbit of BK Peg is slightly eccentric (e = 0.053). The two components are quite different with masses and radii of (1.414 ± 0.007 M⊙, 1.988 ± 0.008 Rsun) and (1.257 ± 0.005 M⊙, 1.474 ± 0.017 Rsun), respectively. The measured rotational velocities are 16.6 ± 0.2 (primary) and 13.4 ± 0.2 (secondary) km s-1. For the secondary component this corresponds to (pseudo)synchronous rotation, whereas the primary component seems to rotate at a slightly lower rate. We derive an iron abundance of [Fe/H] = -0.12 ± 0.07 and similar abundances for Si, Ca, Sc, Ti, Cr and Ni. The stars have evolved to the upper half of the main-sequence band. Yonsei-Yale and Victoria-Regina evolutionary models for the observed metal abundance reproduce BK Peg at ages of 2.75 and 2.50 Gyr, respectively, but tend to predict a lower age for the more massive primary component than for the secondary. We find the same age trend for three other upper main-sequence systems in a sample of well studied eclipsing binaries with components in the 1.15-1.70 M⊙ range. We also find that the Yonsei-Yale models systematically predict higher ages than the Victoria-Regina models. The sample includes BW Aqr, and as a

  12. Results from Source-Based and Detector-Based Calibrations of a CLARREO Calibration Demonstration System

    Science.gov (United States)

    Angal, Amit; Mccorkel, Joel; Thome, Kurt

    2016-01-01

    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 GLAMRs case, are a set of NIST-calibrated transfer radiometers. A portable version of the SOLARIS, Suitcase SOLARIS is used to evaluate GLAMRs 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 (k2) 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 5 (k2) absolute uncertainties. Limitations of the 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. (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  13. STELLAR COLOR REGRESSION: A SPECTROSCOPY-BASED METHOD FOR COLOR CALIBRATION TO A FEW MILLIMAGNITUDE ACCURACY AND THE RECALIBRATION OF STRIPE 82

    International Nuclear Information System (INIS)

    Yuan, Haibo; Liu, Xiaowei; Xiang, Maosheng; Huang, Yang; Zhang, Huihua; Chen, Bingqiu

    2015-01-01

    In this paper we propose a spectroscopy-based stellar color regression (SCR) method to perform accurate color calibration for modern imaging surveys, taking advantage of millions of stellar spectra now available. The method is straightforward, insensitive to systematic errors in the spectroscopically determined stellar atmospheric parameters, applicable to regions that are effectively covered by spectroscopic surveys, and capable of delivering an accuracy of a few millimagnitudes for color calibration. As an illustration, we have applied the method to the Sloan Digital Sky Survey (SDSS) Stripe 82 data. With a total number of 23,759 spectroscopically targeted stars, we have mapped out the small but strongly correlated color zero-point errors present in the photometric catalog of Stripe 82, and we improve the color calibration by a factor of two to three. Our study also reveals some small but significant magnitude dependence errors in the z band for some charge-coupled devices (CCDs). Such errors are likely to be present in all the SDSS photometric data. Our results are compared with those from a completely independent test based on the intrinsic colors of red galaxies presented by Ivezić et al. The comparison, as well as other tests, shows that the SCR method has achieved a color calibration internally consistent at a level of about 5 mmag in u – g, 3 mmag in g – r, and 2 mmag in r – i and i – z. Given the power of the SCR method, we discuss briefly the potential benefits by applying the method to existing, ongoing, and upcoming imaging surveys

  14. Mass Evolution of Mediterranean, Black, Red, and Caspian Seas from GRACE and Altimetry: Accuracy Assessment and Solution Calibration

    Science.gov (United States)

    Loomis, B. D.; Luthcke, S. B.

    2016-01-01

    We present new measurements of mass evolution for the Mediterranean, Black, Red, and Caspian Seas as determined by the NASA Goddard Space Flight Center (GSFC) GRACE time-variable global gravity mascon solutions. These new solutions are compared to sea surface altimetry measurements of sea level anomalies with steric corrections applied. To assess their accuracy, the GRACE and altimetry-derived solutions are applied to the set of forward models used by GSFC for processing the GRACE Level-1B datasets, with the resulting inter-satellite range acceleration residuals providing a useful metric for analyzing solution quality.

  15. Absolute noninvasive measurement of CO2 mole fraction emitted by E. coli and S. aureus using calibration-free 2f WMS applied to a 2004  nm VCSEL.

    Science.gov (United States)

    Zarin, A S; Chakraborty, Arup Lal; Upadhyay, Abhishek

    2017-06-01

    We report the first demonstration, to the best of our knowledge, of accurate real-time noninvasive measurement of the absolute cumulative mole fraction of metabolic carbon dioxide emitted by Escherichia coli and Staphylococcus aureus over a period of several hours of their life cycles using a recently developed calibration-free wavelength modulation spectroscopy technique. A 1 mW vertical-cavity surface-emitting laser is used to interrogate a single rotational vibrational absorption line of carbon dioxide at 2003.5 nm. The measurements are immune to laser intensity fluctuations and variable optical coupling that is inevitable in such free-space coupled experiments that run over 10-18 h. The cumulative carbon dioxide mole fraction follows the characteristic modified Gompertz model that is typical of bacterial growth in batch cultures. The characteristic growth parameters are extracted from this curve. The technique can be readily extended to study multiple volatile organic compounds that bacteria are known to emit.

  16. Calibration of the radiometric asteroid scale using occultation diameters

    Science.gov (United States)

    Brown, R. H.; Morrison, D.; Telesco, C. M.; Brunk, W. E.

    1982-10-01

    The paper describes a new approach to the calibration of the radiometric asteroid scale, which relies on recent accurate occultation measurements of the diameters of 2 Pallas (Wasserman et al., 1979) and 3 Juno (Millis et al., 1981), and the Voyager diameter of J4 Callisto, as well as IR photometry of these objects obtained with the NASA 3-m Infrared Telescope Facility. It is shown that this calibration is internally consistent to better than 5%, and probably has an absolute accuracy of + or - 5%. It is noted that a revision of the TRIAD radiometric diameters downward is required to bring them into agreement with the new calibration.

  17. Online absolute pose compensation and steering control of industrial robot based on six degrees of freedom laser measurement

    Science.gov (United States)

    Yang, Juqing; Wang, Dayong; Fan, Baixing; Dong, Dengfeng; Zhou, Weihu

    2017-03-01

    In-situ intelligent manufacturing for large-volume equipment requires industrial robots with absolute high-accuracy positioning and orientation steering control. Conventional robots mainly employ an offline calibration technology to identify and compensate key robotic parameters. However, the dynamic and static parameters of a robot change nonlinearly. It is not possible to acquire a robot's actual parameters and control the absolute pose of the robot with a high accuracy within a large workspace by offline calibration in real-time. This study proposes a real-time online absolute pose steering control method for an industrial robot based on six degrees of freedom laser tracking measurement, which adopts comprehensive compensation and correction of differential movement variables. First, the pose steering control system and robot kinematics error model are constructed, and then the pose error compensation mechanism and algorithm are introduced in detail. By accurately achieving the position and orientation of the robot end-tool, mapping the computed Jacobian matrix of the joint variable and correcting the joint variable, the real-time online absolute pose compensation for an industrial robot is accurately implemented in simulations and experimental tests. The average positioning error is 0.048 mm and orientation accuracy is better than 0.01 deg. The results demonstrate that the proposed method is feasible, and the online absolute accuracy of a robot is sufficiently enhanced.

  18. 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

  19. ESTIMATION OF RADIOMETRIC CALIBRATION COEFFICIENTS OF EGYPTSAT-1 SENSOR

    Directory of Open Access Journals (Sweden)

    A. H. Nasr

    2012-07-01

    Full Text Available Sensors usually must be calibrated as part of a measurement system. Calibration may include the procedure of correcting the transfer of the sensor, using the reference measurements, in such a way that a specific input-output relation can be guaranteed with a certain accuracy and under certain conditions. It is necessary to perform a calibration to relate the output signal precisely to the physical input signal (e.g., the output Digital Numbers (DNs to the absolute units of at-sensor spectral radiance. Generic calibration data associated with Egyptsat-1 sensor are not provided by the manufacturer. Therefore, this study was conducted to estimate Egyptsat-1 sensor specific calibration data and tabulates the necessary constants for its different multispectral bands. We focused our attention on the relative calibration between Egyptsat-1 and Spot-4 sensors for their great spectral similarity. The key idea is to use concurrent correlation of signals received at both sensors in the same day (i.e., sensors are observing the same phenomenon. Calibration formula constructed from Spot-4 sensor is used to derive the calibration coefficients for Egyptsat-1. A brief overview of the radiometric calibration coefficients retrieval procedures is presented. A reasonable estimate of the overall calibration coefficient is obtained. They have been used to calibrate reflectances of Egyptsat-1 sensor. Further updates to evaluate and improve the retrieved calibration data are being investigated.

  20. Design of a Two-Step Calibration Method of Kinematic Parameters for Serial Robots

    Science.gov (United States)

    WANG, Wei; WANG, Lei; YUN, Chao

    2017-03-01

    Serial robots are used to handle workpieces with large dimensions, and calibrating kinematic parameters is one of the most efficient ways to upgrade their accuracy. Many models are set up to investigate how many kinematic parameters can be identified to meet the minimal principle, but the base frame and the kinematic parameter are indistinctly calibrated in a one-step way. A two-step method of calibrating kinematic parameters is proposed to improve the accuracy of the robot's base frame and kinematic parameters. The forward kinematics described with respect to the measuring coordinate frame are established based on the product-of-exponential (POE) formula. In the first step the robot's base coordinate frame is calibrated by the unit quaternion form. The errors of both the robot's reference configuration and the base coordinate frame's pose are equivalently transformed to the zero-position errors of the robot's joints. The simplified model of the robot's positioning error is established in second-power explicit expressions. Then the identification model is finished by the least square method, requiring measuring position coordinates only. The complete subtasks of calibrating the robot's 39 kinematic parameters are finished in the second step. It's proved by a group of calibration experiments that by the proposed two-step calibration method the average absolute accuracy of industrial robots is updated to 0.23 mm. This paper presents that the robot's base frame should be calibrated before its kinematic parameters in order to upgrade its absolute positioning accuracy.

  1. Accuracy of stress measurement by Laue microdiffraction (Laue-DIC method): the influence of image noise, calibration errors and spot number.

    Science.gov (United States)

    Zhang, F G; Bornert, M; Petit, J; Castelnau, O

    2017-07-01

    Laue microdiffraction, available at several synchrotron radiation facilities, is well suited for measuring the intragranular stress field in deformed materials thanks to the achievable submicrometer beam size. The traditional method for extracting elastic strain (and hence stress) and lattice orientation from a microdiffraction image relies on fitting each Laue spot with an analytical function to estimate the peak position on the detector screen. The method is thus limited to spots exhibiting ellipsoidal shapes, thereby impeding the study of specimens plastically deformed. To overcome this difficulty, the so-called Laue-DIC method introduces digital image correlation (DIC) for the evaluation of the relative positions of spots, which can thus be of any shape. This paper is dedicated to evaluating the accuracy of this Laue-DIC method. First, a simple image noise model is established and verified on the data acquired at beamline BM32 of the European Synchrotron Radiation Facility. Then, the effect of image noise on errors on spot displacement measured by DIC is evaluated by Monte Carlo simulation. Finally, the combined effect of the image noise, calibration errors and the number of Laue spots used for data treatment is investigated. Results in terms of the uncertainty of stress measurement are provided, and various error regimes are identified.

  2. A new network of faint calibration stars from the near infrared spectrometer (NIRS) on the IRTS

    Science.gov (United States)

    Freund, Minoru M.; Matsuura, Mikako; Murakami, Hiroshi; Cohen, Martin; Noda, Manabu; Matsuura, Shuji; Matsumoto, Toshio

    1997-01-01

    The point source extraction and calibration of the near infrared spectrometer (NIRS) onboard the Infrared Telescope in Space (IRTS) is described. About 7 percent of the sky was observed during a one month mission in the range of 1.4 micrometers to 4 micrometers. The accuracy of the spectral shape and absolute values of calibration stars provided by the NIRS/IRTS were validated.

  3. X-ray calibration facility for plasma diagnostics of the MegaJoule laser

    International Nuclear Information System (INIS)

    Hubert, S.; Prevot, V.

    2013-01-01

    The Laser MegaJoule (LMJ) located at CEA-CESTA will be equipped with x-ray plasma diagnostics using different kinds of x-ray components such as filters, mirrors, crystals, detectors and cameras. To guarantee LMJ measurements, detectors such as x-ray cameras need to be regularly calibrated. An x-ray laboratory is devoted to this task and performs absolute x-ray calibrations for similar x-ray cameras running on Laser Integration Line (LIL). This paper presents the x-ray calibration bench with its x-ray tube based High Energy x-ray Source (HEXS) and some calibration results. By mean of an ingenious transposition system under vacuum absolute x-ray calibration of x-ray cameras, like streak and stripline ones, can be carried out. Coupled to a new collimation system with micrometric accuracy on aperture sensitivity quantum efficiency measurements can be achieved with reduced uncertainties. (authors)

  4. Characterization of a self-calibrating, high-precision, stacked-stage, vertical dual-axis goniometer.

    Science.gov (United States)

    Mendenhall, Marcus H; Henins, Albert; Windover, Donald; Cline, James P

    2016-06-01

    We present details on the alignment and calibration of a goniometer assembly consisting two stacked, optically encoded, vertical axis rotation stages. A technique for its calibration is presented that utilizes a stable, uncalibrated, third stage to position a mirror in conjunction with a nulling autocollimator. Such a system provides a self-calibrating set of angular stages with absolute accuracy of ±0.1 second of plane angle (k=2 expanded uncertainty) around the full circle, suitable for laboratory application. This calibration technique permits in situ , absolute angular calibration of an operational goniometer assembly that is requisite for fully traceable angle measurement, as the installation of the encoder is known to change its performance from the angular calibration data provided by the manufacturer.

  5. Cost effective robust rule calibration system

    Directory of Open Access Journals (Sweden)

    Greeff P.

    2014-01-01

    Full Text Available One of the main calibration services of African NMIs (National Metrology Institutes is the measurement of tapes and rules. This is mainly regulated by legal metrology and OIML (International Organisation of Legal Metrology specifications are therefore referenced. Specifically, OIML R-35 is the standard to which rules or line scales must conform. The accuracy of most African NMIs systems however, cannot prove conformance to this specification. This article will detail the development of a new, cost effective, line scale calibration system, which will have accuracy better than the specification prescribed. The system was locally developed and its design is based on off-the-shelf components and open source software. It is also ready-for-upgrade to an absolute system. The system and details of the line detection algorithm will be presented.

  6. 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.

  7. Improvement in the accuracy of polymer gel dosimeters using scintillating fibers

    International Nuclear Information System (INIS)

    Tremblay, Nicolas M; Hubert-Tremblay, Vincent; Bujold, Rachel; Beaulieu, Luc; Lepage, Martin

    2010-01-01

    We propose a novel method for the absolute calibration of polyacrylamide gel (PAG) dosimeters with one or more reference scintillating fiber dosimeters inserted inside the gel. Four calibrated scintillating fibers were inserted into a cylindrical glass container filled with a PAG dosimeter irradiated with a wedge filtered 6 MV photon beam. Calibration curves using small glass vials containing the same gel as the cylindrical containers were used to obtain a first calibration curve. This calibration curve was then adjusted with the dose measured with one of the scintillating fibers in a low gradient part of the field using different approaches. Among these, it was found that a translation of the gel calibration curve yielded the highest accuracy with PAG dosimeters.

  8. Accuracy evaluation of a new real-time continuous glucose monitoring algorithm in hypoglycemia

    DEFF Research Database (Denmark)

    Mahmoudi, Zeinab; Jensen, Morten Hasselstrøm; Johansen, Mette Dencker

    2014-01-01

    UNLABELLED: Abstract Background: The purpose of this study was to evaluate the performance of a new continuous glucose monitoring (CGM) calibration algorithm and to compare it with the Guardian(®) REAL-Time (RT) (Medtronic Diabetes, Northridge, CA) calibration algorithm in hypoglycemia. SUBJECTS...... AND METHODS: CGM data were obtained from 10 type 1 diabetes patients undergoing insulin-induced hypoglycemia. Data were obtained in two separate sessions using the Guardian RT CGM device. Data from the same CGM sensor were calibrated by two different algorithms: the Guardian RT algorithm and a new calibration...... algorithm. The accuracy of the two algorithms was compared using four performance metrics. RESULTS: The median (mean) of absolute relative deviation in the whole range of plasma glucose was 20.2% (32.1%) for the Guardian RT calibration and 17.4% (25.9%) for the new calibration algorithm. The mean (SD...

  9. 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...

  10. Absolute nuclear material assay

    Science.gov (United States)

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  11. Absolute nuclear material assay

    Science.gov (United States)

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  12. Summary of KOMPSAT-5 Calibration and Validation

    Science.gov (United States)

    Yang, D.; Jeong, H.; Lee, S.; Kim, B.

    2013-12-01

    including pointing, relative and absolute calibration as well as geolocation accuracy determination. The absolute calibration will be accomplished by determining absolute radiometric accuracy using already deployed trihedral corner reflectors on calibration and validation sites located southeast from Ulaanbaatar, Mongolia. To establish a measure for the assess the final image products, geolocation accuracies of image products with different imaging modes will be determined by using deployed point targets and available Digital Terrain Model (DTM), and on different image processing levels. In summary, this paper will present calibration and validation activities performed during the LEOP and IOT of KOMPSAT-5. The methodology and procedure of calibration and validation will be explained as well as its results. Based on the results, the applications of SAR image products on geophysical processes will be also discussed.

  13. Calibration of robotic drilling systems with a moving rail

    Directory of Open Access Journals (Sweden)

    Tian Wei

    2014-12-01

    Full Text Available Industrial robots are widely used in aircraft assembly systems such as robotic drilling systems. It is necessary to expand a robot’s working range with a moving rail. A method for improving the position accuracy of an automated assembly system with an industrial robot mounted on a moving rail is proposed. A multi-station method is used to control the robot in this study. The robot only works at stations which are certain positions defined on the moving rail. The calibration of the robot system is composed by the calibration of the robot and the calibration of the stations. The calibration of the robot is based on error similarity and inverse distance weighted interpolation. The calibration of the stations is based on a magnetic strip and a magnetic sensor. Validation tests were performed in this study, which showed that the accuracy of the robot system gained significant improvement using the proposed method. The absolute position errors were reduced by about 85% to less than 0.3 mm compared with the maximum nearly 2 mm before calibration.

  14. ABSOLUTE NEUTRINO MASSES

    DEFF Research Database (Denmark)

    Schechter, J.; Shahid, M. N.

    2012-01-01

    We discuss the possibility of using experiments timing the propagation of neutrino beams over large distances to help determine the absolute masses of the three neutrinos.......We discuss the possibility of using experiments timing the propagation of neutrino beams over large distances to help determine the absolute masses of the three neutrinos....

  15. Accuracy assessment of ALOS optical instruments: PRISM and AVNIR-2

    Science.gov (United States)

    Tadono, Takeo; Shimada, Masanobu; Iwata, Takanori; Takaku, Junichi; Kawamoto, Sachi

    2017-11-01

    This paper describes the updated results of calibration and validation to assess the accuracies for optical instruments onboard the Advanced Land Observing Satellite (ALOS, nicknamed "Daichi"), which was successfully launched on January 24th, 2006 and it is continuously operating very well. ALOS has an L-band Synthetic Aperture Radar called PALSAR and two optical instruments i.e. the Panchromatic Remotesensing Instrument for Stereo Mapping (PRISM) and the Advanced Visible and Near Infrared Radiometer type-2 (AVNIR-2). PRISM consists of three radiometers and is used to derive a digital surface model (DSM) with high spatial resolution that is an objective of the ALOS mission. Therefore, geometric calibration is important in generating a precise DSM with stereo pair images of PRISM. AVNIR-2 has four radiometric bands from blue to near infrared and uses for regional environment and disaster monitoring etc. The radiometric calibration and image quality evaluation are also important for AVNIR-2 as well as PRISM. This paper describes updated results of geometric calibration including geolocation determination accuracy evaluations of PRISM and AVNIR-2, image quality evaluation of PRISM, and validation of generated PRISM DSM. These works will be done during the ALOS mission life as an operational calibration to keep absolute accuracies of the standard products.

  16. Optimization of SPECT calibration for quantification of images applied to dosimetry with iodine-131

    International Nuclear Information System (INIS)

    Carvalho, Samira Marques de

    2018-01-01

    SPECT systems calibration plays an essential role in the accuracy of the quantification of images. In this work, in its first stage, an optimized SPECT calibration method was proposed for 131 I studies, considering the partial volume effect (PVE) and the position of the calibration source. In the second stage, the study aimed to investigate the impact of count density and reconstruction parameters on the determination of the calibration factor and the quantification of the image in dosimetry studies, considering the reality of clinical practice in Brazil. In the final step, the study aimed evaluating the influence of several factors in the calibration for absorbed dose calculation using Monte Carlo simulations (MC) GATE code. Calibration was performed by determining a calibration curve (sensitivity versus volume) obtained by applying different thresholds. Then, the calibration factors were determined with an exponential function adjustment. Images were performed with high and low counts densities for several source positions within the simulator. To validate the calibration method, the calibration factors were used for absolute quantification of the total reference activities. The images were reconstructed adopting two approaches of different parameters, usually used in patient images. The methodology developed for the calibration of the tomographic system was easier and faster to implement than other procedures suggested to improve the accuracy of the results. The study also revealed the influence of the location of the calibration source, demonstrating better precision in the absolute quantification considering the location of the target region during the calibration of the system. The study applied in the Brazilian thyroid protocol suggests the revision of the calibration of the SPECT system, including different positions for the reference source, besides acquisitions considering the Signal to Noise Ratio (SNR) of the images. Finally, the doses obtained with the

  17. Precision spectroscopy with a frequency-comb-calibrated solar spectrograph

    Science.gov (United States)

    Doerr, H.-P.

    2015-06-01

    The measurement of the velocity field of the plasma at the solar surface is a standard diagnostic tool in observational solar physics. Detailed information about the energy transport as well as on the stratification of temperature, pressure and magnetic fields in the solar atmosphere are encoded in Doppler shifts and in the precise shape of the spectral lines. The available instruments deliver data of excellent quality and precision. However, absolute wavelength calibration in solar spectroscopy was so far mostly limited to indirect methods and in general suffers from large systematic uncertainties of the order of 100 m/s. During the course of this thesis, a novel wavelength calibration system based on a laser frequency comb was deployed to the solar Vacuum Tower Telescope (VTT), Tenerife, with the goal of enabling highly accurate solar wavelength measurements at the level of 1 m/s on an absolute scale. The frequency comb was developed in a collaboration between the Kiepenheuer-Institute for Solar Physics, Freiburg, Germany and the Max Planck Institute for Quantum Optics, Garching, Germany. The efforts cumulated in the new prototype instrument LARS (Lars is an Absolute Reference Spectrograph) for solar precision spectroscopy which is in preliminary scientific operation since~2013. The instrument is based on the high-resolution echelle spectrograph of the VTT for which feed optics based on single-mode optical fibres were developed for this project. The setup routinely achieves an absolute calibration accuracy of 60 cm/s and a repeatability of 2.5 cm/s. An unprecedented repeatability of only 0.32 cm/s could be demonstrated with a differential calibration scheme. In combination with the high spectral resolving power of the spectrograph of 7x10^5 and virtually absent internal scattered light, LARS provides a spectral purity and fidelity that previously was the domain of Fourier-transform spectrometers only. The instrument therefore provides unique capabilities for

  18. Improvement of the Ca determination accuracy with k (0)-INAA using an HPGe coaxial detector with extended energy range efficiency calibration

    Czech Academy of Sciences Publication Activity Database

    Kučera, Jan; Kubešová, Marie; Lebeda, Ondřej

    2018-01-01

    Roč. 315, č. 3 (2018), s. 671-675 ISSN 0236-5731. [7th International K0-Users Workshop. Montreal, 03.09.2017-08.09.2017] R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : k(0)-INAA * Ca determination * HPGe detector * High- energy efficiency calibration * Co-56 activity standard Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 1.282, year: 2016

  19. NGS Absolute Gravity Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NGS Absolute Gravity data (78 stations) was received in July 1993. Principal gravity parameters include Gravity Value, Uncertainty, and Vertical Gradient. The...

  20. Decoherence at absolute zero

    OpenAIRE

    Sinha, Supurna

    2005-01-01

    We present an analytical study of the loss of quantum coherence at absolute zero. Our model consists of a harmonic oscillator coupled to an environment of harmonic oscillators at absolute zero. We find that for an Ohmic bath, the offdiagonal elements of the density matrix in the position representation decay as a power law in time at late times. This slow loss of coherence in the quantum domain is qualitatively different from the exponential decay observed in studies of high temperature envir...

  1. Stimulus Probability Effects in Absolute Identification

    Science.gov (United States)

    Kent, Christopher; Lamberts, Koen

    2016-01-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of…

  2. Invited Article: Deep Impact instrument calibration.

    Science.gov (United States)

    Klaasen, Kenneth P; A'Hearn, Michael F; Baca, Michael; Delamere, Alan; Desnoyer, Mark; Farnham, Tony; Groussin, Olivier; Hampton, Donald; Ipatov, Sergei; Li, Jianyang; Lisse, Carey; Mastrodemos, Nickolaos; McLaughlin, Stephanie; Sunshine, Jessica; Thomas, Peter; Wellnitz, Dennis

    2008-09-01

    Calibration of NASA's Deep Impact spacecraft instruments allows reliable scientific interpretation of the images and spectra returned from comet Tempel 1. Calibrations of the four onboard remote sensing imaging instruments have been performed in the areas of geometric calibration, spatial resolution, spectral resolution, and radiometric response. Error sources such as noise (random, coherent, encoding, data compression), detector readout artifacts, scattered light, and radiation interactions have been quantified. The point spread functions (PSFs) of the medium resolution instrument and its twin impactor targeting sensor are near the theoretical minimum [ approximately 1.7 pixels full width at half maximum (FWHM)]. However, the high resolution instrument camera was found to be out of focus with a PSF FWHM of approximately 9 pixels. The charge coupled device (CCD) read noise is approximately 1 DN. Electrical cross-talk between the CCD detector quadrants is correctable to <2 DN. The IR spectrometer response nonlinearity is correctable to approximately 1%. Spectrometer read noise is approximately 2 DN. The variation in zero-exposure signal level with time and spectrometer temperature is not fully characterized; currently corrections are good to approximately 10 DN at best. Wavelength mapping onto the detector is known within 1 pixel; spectral lines have a FWHM of approximately 2 pixels. About 1% of the IR detector pixels behave badly and remain uncalibrated. The spectrometer exhibits a faint ghost image from reflection off a beamsplitter. Instrument absolute radiometric calibration accuracies were determined generally to <10% using star imaging. Flat-field calibration reduces pixel-to-pixel response differences to approximately 0.5% for the cameras and <2% for the spectrometer. A standard calibration image processing pipeline is used to produce archival image files for analysis by researchers.

  3. A high-accuracy two-position alignment inertial navigation system for lunar rovers aided by a star sensor with a calibration and positioning function

    International Nuclear Information System (INIS)

    Lu, Jiazhen; Lei, Chaohua; Yang, Yanqiang; Liu, Ming

    2016-01-01

    An integrated inertial/celestial navigation system (INS/CNS) has wide applicability in lunar rovers as it provides accurate and autonomous navigational information. Initialization is particularly vital for a INS. This paper proposes a two-position initialization method based on a standard Kalman filter. The difference between the computed star vector and the measured star vector is measured. With the aid of a star sensor and the two positions, the attitudinal and positional errors can be greatly reduced, and the biases of three gyros and accelerometers can also be estimated. The semi-physical simulation results show that the positional and attitudinal errors converge within 0.07″ and 0.1 m, respectively, when the given initial positional error is 1 km and the attitudinal error is 10°. These good results show that the proposed method can accomplish alignment, positioning and calibration functions simultaneously. Thus the proposed two-position initialization method has the potential for application in lunar rover navigation. (paper)

  4. Approach to Absolute Zero

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 6. Approach to Absolute Zero 0.3 K. to a Few Milli-Kelvin. R Srinivasan. Series Article Volume 2 Issue 6 June 1997 pp 6-14. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/002/06/0006-0014 ...

  5. Approach to Absolute Zero

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 2. Approach to Absolute Zero From 4. 22 K. to 0. 3 K. R Srinivasan. Series Article Volume 2 Issue 2 February 1997 pp 8-16. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/002/02/0008-0016 ...

  6. Approach to Absolute Zero

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 10. Approach to Absolute Zero Below 10 milli-Kelvin. R Srinivasan. Series Article Volume 2 Issue 10 October 1997 pp 8-16. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/002/10/0008-0016 ...

  7. Approach to Absolute Zero

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 10. Approach to Absolute Zero Below 10 milli-Kelvin. R Srinivasan. Series Article Volume 2 Issue 10 October 1997 pp 8-16. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/002/10/0008-0016 ...

  8. Absolute pitch--electrophysiological evidence.

    Science.gov (United States)

    Barnea, A; Granot, R; Pratt, H

    1994-02-01

    People who have the ability to label or to produce notes without any reference are considered to possess Absolute Pitch (AP). Others, who need a reference in order to identify the notes, possess Relative Pitch (RP). The AP ability is assumed to reflect a unique, language-like representation of non-lexical musical notes in memory. The purpose of this study was to examine this assumption by comparing Event Related Potentials (ERP) of musicians with and without AP, to lexical and non-lexical representation of musical material. Subjects were eighteen young adult musicians. Seven were AP and eleven RP. Auditory stimuli, presented through earphones, were piano notes (non-lexical) or a voice saying the note's name (lexical). Visual stimuli, presented on a computer display were note symbols (non-lexical) or letters (lexical). Subjects performed a number of tasks, combining the two modalities (visual and auditory) and stimulus types (lexical and non-lexical), and reaction times (RT), performance accuracy and evoked potentials were recorded. The tasks forced the subjects to transfer mental representations of musical material from one mode to another. Our most important findings were the differences, between groups, in the scalp distribution of P300 amplitudes. We conclude that absolute pitch possessors use the same internal language as relative pitch possessors, when possible, but the distribution of the underlying brain activity is different between AP and RP subjects.

  9. South African initiative for pre-flight radiometric calibration of satellite imagers

    CSIR Research Space (South Africa)

    Griffith, D

    2009-07-01

    Full Text Available integrating sphere with conventional lamps for absolute radiance response calibration and a multi-grating turret monochromator system for the relative spectral response calibration. The calibration hardware is housed in a class 100 000 clean room area.... 2. ABSOLUTE RADIOMETRIC CALIBRATION Absolute radiometric calibration is performed using a LabSphere USS4000C integrating sphere furnished with a set of Quartz Tungsten Halogen (QTH) lamps driven by precision current controllers...

  10. Portable compact multifunction IR calibrator

    International Nuclear Information System (INIS)

    Wyatt, C.L.; Jacobsen, L.; Steed, A.

    1988-01-01

    A compact portable multifunction calibrator designed for future sensor systems is described which enables a linearity calibration for all detectors simultaneously using a near small-area source, a high-resolution mapping of the focal plane with 10 microrad setability and with a blur of less than 100 microrad, system spectral response calibration (radiometer) using a Michelson interferometer source, relative spectral response (spectrometer) using high-temperature external commercial blackbody simulators, and an absolute calibration using an internal low-temperature extended-area source. 5 references

  11. Fundamental principles of absolute radiometry and the philosophy of this NBS program (1968 to 1971)

    Science.gov (United States)

    Geist, J.

    1972-01-01

    A description is given work performed on a program to develop an electrically calibrated detector (also called absolute radiometer, absolute detector, and electrically calibrated radiometer) that could be used to realize, maintain, and transfer a scale of total irradiance. The program includes a comprehensive investigation of the theoretical basis of absolute detector radiometry, as well as the design and construction of a number of detectors. A theoretical analysis of the sources of error is also included.

  12. Spectral and Radiometric Calibration using Tunable Lasers Project

    Data.gov (United States)

    National Aeronautics and Space Administration —  SIRCUS-based calibration relies on a set of monitoring radiometers and tunable laser sources to provide an absolute radiometric calibration that can approach...

  13. Magnitude and accuracy differences between judgements of remembering and forgetting.

    Science.gov (United States)

    Serra, Michael J; England, Benjamin D

    2012-01-01

    Metacognition researchers have recently begun to examine the effects of framing judgements of learning (JOLs) in terms of forgetting (rather than remembering) on the judgements' magnitude and accuracy. Although a promising new direction for the study of metamemory, initial studies have yielded inconsistent results. To help resolve these inconsistencies, in four experiments we had college students (N = 434) study paired associates and make JOLs framed in terms of either remembering or forgetting over two study-test trials. Our goals were to further document the effects of framing on the magnitude and accuracy of JOLs and to consider explanations for why specific patterns tend to emerge. The present experiments provide evidence that (a) judgements of forgetting are psychologically anchored at the midpoint of the JOL scale, whereas judgements of remembering are anchored at a lower point, (b) differences in absolute accuracy (calibration) by frame are largely artefactual and stem from differences in anchoring, (c) differences in JOL magnitude and absolute accuracy by frame do not obtain when memory cues are salient to participants, and (d) a forget frame impairs the relative accuracy (resolution) of JOLs across trials by reducing participants' reliance on cues such as memory for past test performance.

  14. Mars Exploration Rover Navigation Camera in-flight calibration

    Science.gov (United States)

    Soderblom, J.M.; Bell, J.F.; Johnson, J. R.; Joseph, J.; Wolff, M.J.

    2008-01-01

    The Navigation Camera (Navcam) instruments on the Mars Exploration Rover (MER) spacecraft provide support for both tactical operations as well as scientific observations where color information is not necessary: large-scale morphology, atmospheric monitoring including cloud observations and dust devil movies, and context imaging for both the thermal emission spectrometer and the in situ instruments on the Instrument Deployment Device. The Navcams are a panchromatic stereoscopic imaging system built using identical charge-coupled device (CCD) detectors and nearly identical electronics boards as the other cameras on the MER spacecraft. Previous calibration efforts were primarily focused on providing a detailed geometric calibration in line with the principal function of the Navcams, to provide data for the MER navigation team. This paper provides a detailed description of a new Navcam calibration pipeline developed to provide an absolute radiometric calibration that we estimate to have an absolute accuracy of 10% and a relative precision of 2.5%. Our calibration pipeline includes steps to model and remove the bias offset, the dark current charge that accumulates in both the active and readout regions of the CCD, and the shutter smear. It also corrects pixel-to-pixel responsivity variations using flat-field images, and converts from raw instrument-corrected digital number values per second to units of radiance (W m-2 nm-1 sr-1), or to radiance factor (I/F). We also describe here the initial results of two applications where radiance-calibrated Navcam data provide unique information for surface photometric and atmospheric aerosol studies. Copyright 2008 by the American Geophysical Union.

  15. Analysis of thermal power calibration method

    International Nuclear Information System (INIS)

    Zagar, T.; Ravnik, M.; Persic, A.

    2000-01-01

    The methods for determining fuel element burnup have recently become interesting because of activities related to the shipment of highly enriched fuel elements back to the United States for final disposal before 2009. The most common and practical method for determining fuel element burnup in research reactors is reactor calculation. Experience has shown that burnup calculations become complicated and biased with uncertainties if a long period of reactor operation must be reproduced. Besides this, accuracy of calculated burnup is always limited with accuracy of reactor power calibration, since burnup calculation is based on calculated power density distribution, which is usually expressed in terms of power released per fuel element and normalised to the reactor power It is obvious that reactor thermal power calibration is very important for precise fuel element burnup calculation. Calculated fuel element burnup is linearly dependent on the thermal reactor power. The reactor power level may be determined from measured absolute thermal flux distribution across the core in the horizontal and vertical planes. Flux distributions are measured with activation of cadmium covered and bare foils irradiated by the steady reactor power. But it should be realised that this method is time consuming and not accurate. This method is practical only for zero power reactors and is in practice very seldom performed for other reactors (e.g. for TRIGA reactor in Ljubljana absolute thermal flux distribution was not performed since reactor reconstruction in 1991). In case of power reactors and research reactors in which a temperature rise across the core is produced and measured than a heat balance method is the most common and accurate method of determining the power output of the core. The purpose of this paper is to analyse the accuracy of calorimetric reactor power calibration method and to analyse the influence of control rod position on nuclear detector reading for TRIGA reactors

  16. Calibration and uncertainty in electromagnetic fields measuring methods

    International Nuclear Information System (INIS)

    Anglesio, L.; Crotti, G.; Borsero, M.; Vizio, G.

    1999-01-01

    Calibration and reliability in electromagnetic field measuring methods are assured by calibration of measuring instruments. In this work are illustrated systems for generation of electromagnetic fields at low and high frequency, calibration standard and accuracy [it

  17. Accuracy and consistency of weights provided by home bathroom scales.

    Science.gov (United States)

    Yorkin, Meredith; Spaccarotella, Kim; Martin-Biggers, Jennifer; Quick, Virginia; Byrd-Bredbenner, Carol

    2013-12-17

    Self-reported body weight is often used for calculation of Body Mass Index because it is easy to collect. Little is known about sources of error introduced by using bathroom scales to measure weight at home. The objective of this study was to evaluate the accuracy and consistency of digital versus dial-type bathroom scales commonly used for self-reported weight. Participants brought functioning bathroom scales (n=18 dial-type, n=43 digital-type) to a central location. Trained researchers assessed accuracy and consistency using certified calibration weights at 10 kg, 25 kg, 50 kg, 75 kg, 100 kg, and 110 kg. Data also were collected on frequency of calibration, age and floor surface beneath the scale. All participants reported using their scale on hard surface flooring. Before calibration, all digital scales displayed 0, but dial scales displayed a mean absolute initial weight of 0.95 (1.9 SD) kg. Digital scales accurately weighed test loads whereas dial-type scale weights differed significantly (pdigital scales at all weights (pDigital home bathroom scales provide sufficiently accurate and consistent weights for public health research. Reminders to zero scales before each use may further improve accuracy of self-reported weight.

  18. An integrated approach to monitoring the calibration stability of operational dual-polarization radars

    Directory of Open Access Journals (Sweden)

    M. Vaccarono

    2016-11-01

    Full Text Available The stability of weather radar calibration is a mandatory aspect for quantitative applications, such as rainfall estimation, short-term weather prediction and initialization of numerical atmospheric and hydrological models. Over the years, calibration monitoring techniques based on external sources have been developed, specifically calibration using the Sun and calibration based on ground clutter returns. In this paper, these two techniques are integrated and complemented with a self-consistency procedure and an intercalibration technique. The aim of the integrated approach is to implement a robust method for online monitoring, able to detect significant changes in the radar calibration. The physical consistency of polarimetric radar observables is exploited using the self-consistency approach, based on the expected correspondence between dual-polarization power and phase measurements in rain. This technique allows a reference absolute value to be provided for the radar calibration, from which eventual deviations may be detected using the other procedures. In particular, the ground clutter calibration is implemented on both polarization channels (horizontal and vertical for each radar scan, allowing the polarimetric variables to be monitored and hardware failures to promptly be recognized. The Sun calibration allows monitoring the calibration and sensitivity of the radar receiver, in addition to the antenna pointing accuracy. It is applied using observations collected during the standard operational scans but requires long integration times (several days in order to accumulate a sufficient amount of useful data. Finally, an intercalibration technique is developed and performed to compare colocated measurements collected in rain by two radars in overlapping regions. The integrated approach is performed on the C-band weather radar network in northwestern Italy, during July–October 2014. The set of methods considered appears suitable to establish

  19. Absolute Gravimetry in Fennoscandia

    DEFF Research Database (Denmark)

    Pettersen, B. R; TImmen, L.; Gitlein, O.

    away from this central location. An oval shaped zero uplift isoline tracks the general western and northern coastline of Norway and the Kola peninsula. It returns southwest through Russian Karelia and touches the southern tip of Sweden and northern Denmark. The uplift area (as measured by present day...... motions) has its major axis in the direction of southwest to northeast and covers a distance of about 2000 km. Absolute gravimetry was made in Finland and Norway in 1976 with a rise-and fall instrument. A decade later the number of gravity stations was expanded by JILAg-5, in Finland from 1988, in Norway...... acquired by IfE (FG5-220), FGI (FG5-221), and UMB (FG5-226). New absolute gravity stations were established by the national mapping agencies in Denmark, Norway, and Sweden. The total number of prepared sites in Fennoscandia is now about 30. Most of them are co-located with permanent GPS, for many of which...

  20. 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...

  1. Absolute beam current monitoring in endstation c

    International Nuclear Information System (INIS)

    Bochna, C.

    1995-01-01

    The first few experiments at CEBAF require approximately 1% absolute measurements of beam currents expected to range from 10-25μA. This represents errors of 100-250 nA. The initial complement of beam current monitors are of the non intercepting type. CEBAF accelerator division has provided a stripline monitor and a cavity monitor, and the authors have installed an Unser monitor (parametric current transformer or PCT). After calibrating the Unser monitor with a precision current reference, the authors plan to transfer this calibration using CW beam to the stripline monitors and cavity monitors. It is important that this be done fairly rapidly because while the gain of the Unser monitor is quite stable, the offset may drift on the order of .5μA per hour. A summary of what the authors have learned about the linearity, zero drift, and gain drift of each type of current monitor will be presented

  2. Thermodynamics of negative absolute pressures

    International Nuclear Information System (INIS)

    Lukacs, B.; Martinas, K.

    1984-03-01

    The authors show that the possibility of negative absolute pressure can be incorporated into the axiomatic thermodynamics, analogously to the negative absolute temperature. There are examples for such systems (GUT, QCD) processing negative absolute pressure in such domains where it can be expected from thermodynamical considerations. (author)

  3. PERFORMANCE ASSESSMENT AND GEOMETRIC CALIBRATION OF RESOURCESAT-2

    Directory of Open Access Journals (Sweden)

    P. V. Radhadevi

    2016-06-01

    Full Text Available Resourcesat-2 (RS-2 has successfully completed five years of operations in its orbit. This satellite has multi-resolution and multi-spectral capabilities in a single platform. A continuous and autonomous co-registration, geo-location and radiometric calibration of image data from different sensors with widely varying view angles and resolution was one of the challenges of RS-2 data processing. On-orbit geometric performance of RS-2 sensors has been widely assessed and calibrated during the initial phase operations. Since then, as an ongoing activity, various geometric performance data are being generated periodically. This is performed with sites of dense ground control points (GCPs. These parameters are correlated to the direct geo-location accuracy of the RS-2 sensors and are monitored and validated to maintain the performance. This paper brings out the geometric accuracy assessment, calibration and validation done for about 500 datasets of RS-2. The objectives of this study are to ensure the best absolute and relative location accuracy of different cameras, location performance with payload steering and co-registration of multiple bands. This is done using a viewing geometry model, given ephemeris and attitude data, precise camera geometry and datum transformation. In the model, the forward and reverse transformations between the coordinate systems associated with the focal plane, payload, body, orbit and ground are rigorously and explicitly defined. System level tests using comparisons to ground check points have validated the operational geo-location accuracy performance and the stability of the calibration parameters.

  4. In-situ calibration of nuclear-plant platinum resistance thermometers using Johnson noise methods. Final report

    International Nuclear Information System (INIS)

    Blalock, T.V.; Shepard, R.L.

    1983-06-01

    Methods for in situ calibration of reactor plant platinum resistance thermometers using Johnson noise measurements were tested in the laboratory and in two operating reactors: Diablo Canyon and Sequoyah. The Johnson noise methods provide an absolute measurement of the thermometer temperature and can be compared with the dc calibration of the thermometers to confirm their calibration without removing the thermometers from the plant coolant loops. Inaccuracies of less than 0.1% were obtained with these methods for ideal situations where the noise measuring equipment could be connected directly to the installed thermometer terminals. For measurements made at the ends of long extension cables, inaccuracies were 0.5 to 1.0%, at best. Extension cables must be optimized and well characterized electrically to achieve such accuracies. Other factors that affect the accuracy of these methods were evaluated

  5. Numerical evaluation of magnetic absolute measurements with arbitrarily distributed DI-fluxgate theodolite orientations

    Directory of Open Access Journals (Sweden)

    H.-P. Brunke

    2018-01-01

    Full Text Available At geomagnetic observatories the absolute measurements are needed to determine the calibration parameters of the continuously recording vector magnetometer (variometer. Absolute measurements are indispensable for determining the vector of the geomagnetic field over long periods of time. A standard DI (declination, inclination measuring scheme for absolute measurements establishes routines in magnetic observatories. The traditional measuring schema uses a fixed number of eight orientations (Jankowski et al., 1996.We present a numerical method, allowing for the evaluation of an arbitrary number (minimum of five as there are five independent parameters of telescope orientations. Our method provides D, I and Z base values and calculated error bars of them.A general approach has significant advantages. Additional measurements may be seamlessly incorporated for higher accuracy. Individual erroneous readings are identified and can be discarded without invalidating the entire data set. A priori information can be incorporated. We expect the general method to also ease requirements for automated DI-flux measurements. The method can reveal certain properties of the DI theodolite which are not captured by the conventional method.Based on the alternative evaluation method, a new faster and less error-prone measuring schema is presented. It avoids needing to calculate the magnetic meridian prior to the inclination measurements.Measurements in the vicinity of the magnetic equator are possible with theodolites and without a zenith ocular.The implementation of the method in MATLAB is available as source code at the GFZ Data Center Brunke (2017.

  6. Numerical evaluation of magnetic absolute measurements with arbitrarily distributed DI-fluxgate theodolite orientations

    Science.gov (United States)

    Brunke, Heinz-Peter; Matzka, Jürgen

    2018-01-01

    At geomagnetic observatories the absolute measurements are needed to determine the calibration parameters of the continuously recording vector magnetometer (variometer). Absolute measurements are indispensable for determining the vector of the geomagnetic field over long periods of time. A standard DI (declination, inclination) measuring scheme for absolute measurements establishes routines in magnetic observatories. The traditional measuring schema uses a fixed number of eight orientations (Jankowski et al., 1996).We present a numerical method, allowing for the evaluation of an arbitrary number (minimum of five as there are five independent parameters) of telescope orientations. Our method provides D, I and Z base values and calculated error bars of them.A general approach has significant advantages. Additional measurements may be seamlessly incorporated for higher accuracy. Individual erroneous readings are identified and can be discarded without invalidating the entire data set. A priori information can be incorporated. We expect the general method to also ease requirements for automated DI-flux measurements. The method can reveal certain properties of the DI theodolite which are not captured by the conventional method.Based on the alternative evaluation method, a new faster and less error-prone measuring schema is presented. It avoids needing to calculate the magnetic meridian prior to the inclination measurements.Measurements in the vicinity of the magnetic equator are possible with theodolites and without a zenith ocular.The implementation of the method in MATLAB is available as source code at the GFZ Data Center Brunke (2017).

  7. Montagem e acurácia de um sistema experimental de pesagem para calibração de sensores de umidade do solo Assembling and accuracy of an experimental weighing system for calibration of soil moisture sensors

    Directory of Open Access Journals (Sweden)

    Ricardo Martins Santos

    2006-12-01

    , 10 and 20 kg were used during seven loading and unloading cycles. A linear calibration model (r² = 0.999 was found and the repeatability, hysteresis, and linearity errors were 0.119%, 0.068%, and 0.009% of full scale (FS. The accuracy limits, which represent the overall performance of the weighing system, were ±0.083% of FS. The weighing system, in terms of functionality and performance, were considered to be adequate for calibration of soil moisture sensors, like capacitance probes, with undisturbed soil samples under laboratory conditions. The estimated final cost of the system was US$ 766.00.

  8. 14 MeV calibration of JET neutron detectors—phase 1: calibration and characterization of the neutron source

    Science.gov (United States)

    Batistoni, P.; Popovichev, S.; Cufar, A.; Ghani, Z.; Giacomelli, L.; Jednorog, S.; Klix, A.; Lilley, S.; Laszynska, E.; Loreti, S.; Packer, L.; Peacock, A.; Pillon, M.; Price, R.; Rebai, M.; Rigamonti, D.; Roberts, N.; Tardocchi, M.; Thomas, D.; Contributors, JET

    2018-02-01

    In view of the planned DT operations at JET, a calibration of the JET neutron monitors at 14 MeV neutron energy is needed using a 14 MeV neutron generator deployed inside the vacuum vessel by the JET remote handling system. The target accuracy of this calibration is  ±10% as also required by ITER, where a precise neutron yield measurement is important, e.g. for tritium accountancy. To achieve this accuracy, the 14 MeV neutron generator selected as the calibration source has been fully characterised and calibrated prior to the in-vessel calibration of the JET monitors. This paper describes the measurements performed using different types of neutron detectors, spectrometers, calibrated long counters and activation foils which allowed us to obtain the neutron emission rate and the anisotropy of the neutron generator, i.e. the neutron flux and energy spectrum dependence on emission angle, and to derive the absolute emission rate in 4π sr. The use of high resolution diamond spectrometers made it possible to resolve the complex features of the neutron energy spectra resulting from the mixed D/T beam ions reacting with the D/T nuclei present in the neutron generator target. As the neutron generator is not a stable neutron source, several monitoring detectors were attached to it by means of an ad hoc mechanical structure to continuously monitor the neutron emission rate during the in-vessel calibration. These monitoring detectors, two diamond diodes and activation foils, have been calibrated in terms of neutrons/counts within  ±5% total uncertainty. A neutron source routine has been developed, able to produce the neutron spectra resulting from all possible reactions occurring with the D/T ions in the beam impinging on the Ti D/T target. The neutron energy spectra calculated by combining the source routine with a MCNP model of the neutron generator have been validated by the measurements. These numerical tools will be key in analysing the results from the in

  9. Accuracy of the LEP Spectrometer Beam Orbit Monitors

    CERN Document Server

    Barbero, E; Prochnow, J; Bergoz, J; Unser, K; Matheson, J; Torrence, E

    2001-01-01

    At the LEP e+/e- collider, a spectrometer is used to determine the beam energy with a target accuracy of 10-4. The spectrometer measures the lattice dipole bending angle of the beam using six beam position monitors (BPMs). The required calibration error imposes a BPM accuracy of a 10-6 m corresponding to a relative electrical signal variation of 2. 10-5. The operating parameters have been compared with beam simulator results and non-linearBPM response simulations. The relative beam current variations between 0.02 and 0.03 and position changes of 0.1 mm during the fills of last year lead to uncertainties in the orbit measurements of well below 10-6 m. For accuracy tests absolute beam currents were varied by a factor of three. The environment magnetical field is introduced to correct orbit readings. The BPM linearity and calibration was checked using moveable supports and wire position sensors. The BPM triplet quantity is used to determine the orbit position monitors accuracy. The BPM triplet changed during the...

  10. Systematic calibration of an integrated x-ray and optical tomography system for preclinical radiation research

    International Nuclear Information System (INIS)

    Yang, Yidong; Wang, Ken Kang-Hsin; Wong, John W.; Eslami, Sohrab; Iordachita, Iulian I.; Patterson, Michael S.

    2015-01-01

    Purpose: The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides excellent bone to soft tissue contrast, but is incapable of differentiating tumors from surrounding soft tissue. Bioluminescence tomography (BLT), in contrast, allows direct visualization of even subpalpable tumors and quantitative evaluation of tumor response. Integration of BLT with CBCT offers complementary image information, with CBCT delineating anatomic structures and BLT differentiating luminescent tumors. This study is to develop a systematic method to calibrate an integrated CBCT and BLT imaging system which can be adopted onboard the SARRP to guide focal tumor irradiation. Methods: The integrated imaging system consists of CBCT, diffuse optical tomography (DOT), and BLT. The anatomy acquired from CBCT and optical properties acquired from DOT serve as a priori information for the subsequent BLT reconstruction. Phantoms were designed and procedures were developed to calibrate the CBCT, DOT/BLT, and the entire integrated system. Geometrical calibration was performed to calibrate the CBCT system. Flat field correction was performed to correct the nonuniform response of the optical imaging system. Absolute emittance calibration was performed to convert the camera readout to the emittance at the phantom or animal surface, which enabled the direct reconstruction of the bioluminescence source strength. Phantom and mouse imaging were performed to validate the calibration. Results: All calibration procedures were successfully performed. Both CBCT of a thin wire and a euthanized mouse revealed no spatial artifact, validating the accuracy of the CBCT calibration. The absolute emittance calibration was validated with a 650 nm laser source, resulting in a 3

  11. Systematic calibration of an integrated x-ray and optical tomography system for preclinical radiation research

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yidong, E-mail: yidongyang@med.miami.edu [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231 and Department of Radiation Oncology, University of Miami School of Medicine, Miami, Florida 33136 (United States); Wang, Ken Kang-Hsin; Wong, John W. [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231 (United States); Eslami, Sohrab; Iordachita, Iulian I. [Laboratory for Computational Sensing and Robotics, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Patterson, Michael S. [Juravinski Cancer Centre and Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario L8S4K1 (Canada)

    2015-04-15

    Purpose: The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides excellent bone to soft tissue contrast, but is incapable of differentiating tumors from surrounding soft tissue. Bioluminescence tomography (BLT), in contrast, allows direct visualization of even subpalpable tumors and quantitative evaluation of tumor response. Integration of BLT with CBCT offers complementary image information, with CBCT delineating anatomic structures and BLT differentiating luminescent tumors. This study is to develop a systematic method to calibrate an integrated CBCT and BLT imaging system which can be adopted onboard the SARRP to guide focal tumor irradiation. Methods: The integrated imaging system consists of CBCT, diffuse optical tomography (DOT), and BLT. The anatomy acquired from CBCT and optical properties acquired from DOT serve as a priori information for the subsequent BLT reconstruction. Phantoms were designed and procedures were developed to calibrate the CBCT, DOT/BLT, and the entire integrated system. Geometrical calibration was performed to calibrate the CBCT system. Flat field correction was performed to correct the nonuniform response of the optical imaging system. Absolute emittance calibration was performed to convert the camera readout to the emittance at the phantom or animal surface, which enabled the direct reconstruction of the bioluminescence source strength. Phantom and mouse imaging were performed to validate the calibration. Results: All calibration procedures were successfully performed. Both CBCT of a thin wire and a euthanized mouse revealed no spatial artifact, validating the accuracy of the CBCT calibration. The absolute emittance calibration was validated with a 650 nm laser source, resulting in a 3

  12. ACCURACY TEST OF MICROSOFT KINECT FOR HUMAN MORPHOLOGIC MEASUREMENTS

    Directory of Open Access Journals (Sweden)

    B. Molnár

    2012-08-01

    Full Text Available The Microsoft Kinect sensor, a popular gaming console, is widely used in a large number of applications, including close-range 3D measurements. This low-end device is rather inexpensive compared to similar active imaging systems. The Kinect sensors include an RGB camera, an IR projector, an IR camera and an audio unit. The human morphologic measurements require high accuracy with fast data acquisition rate. To achieve the highest accuracy, the depth sensor and the RGB camera should be calibrated and co-registered to achieve high-quality 3D point cloud as well as optical imagery. Since this is a low-end sensor, developed for different purpose, the accuracy could be critical for 3D measurement-based applications. Therefore, two types of accuracy test are performed: (1 for describing the absolute accuracy, the ranging accuracy of the device in the range of 0.4 to 15 m should be estimated, and (2 the relative accuracy of points depending on the range should be characterized. For the accuracy investigation, a test field was created with two spheres, while the relative accuracy is described by sphere fitting performance and the distance estimation between the sphere center points. Some other factors can be also considered, such as the angle of incidence or the material used in these tests. The non-ambiguity range of the sensor is from 0.3 to 4 m, but, based on our experiences, it can be extended up to 20 m. Obviously, this methodology raises some accuracy issues which make accuracy testing really important.

  13. In-Flight Measurement of the Absolute Energy Scale of the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, M.; /Stanford U., HEPL /SLAC /KIPAC, Menlo Park; Ajello, M.; /Stanford U., HEPL /SLAC /KIPAC, Menlo Park; Allafort, A.; /Stanford U., HEPL /SLAC /KIPAC, Menlo Park; Atwood, W.B.; /UC, Santa Cruz; Axelsson, M.; /Stockholm U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm; Baldini, L.; /INFN, Pisa; Barbiellini, G.; /INFN, Trieste /Trieste U.; Bastieri, D.; /INFN, Padua /Padua U.; Bechtol, K.; /Stanford U., HEPL /SLAC /KIPAC, Menlo Park; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /Stanford U., HEPL /SLAC /KIPAC, Menlo Park; Bloom, E.D.; /Stanford U., HEPL /SLAC /KIPAC, Menlo Park; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /SLAC /KIPAC, Menlo Park; Bouvier, A.; /UC, Santa Cruz; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari Polytechnic /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Buehler, R.; /Stanford U., HEPL /SLAC /KIPAC, Menlo Park; Buson, S.; /INFN, Padua /Padua U. /CSIC, Catalunya /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /Unlisted, US /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /ASDC, Frascati /Perugia U. /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /Montpellier U. /ASDC, Frascati /Bari Polytechnic /INFN, Bari /Naval Research Lab, Wash., D.C. /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /Montpellier U. /Bari Polytechnic /INFN, Bari /Ecole Polytechnique /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /Ecole Polytechnique /Hiroshima U. /Stanford U., HEPL /SLAC /KIPAC, Menlo Park /Bari Polytechnic /INFN, Bari /INFN, Bari /NASA, Goddard /INFN, Perugia /Perugia U.; /more authors..

    2012-09-20

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to survey the gamma-ray sky from 20 MeV to several hundreds of GeV. In this energy band there are no astronomical sources with sufficiently well known and sharp spectral features to allow an absolute calibration of the LAT energy scale. However, the geomagnetic cutoff in the cosmic ray electron-plus-positron (CRE) spectrum in low Earth orbit does provide such a spectral feature. The energy and spectral shape of this cutoff can be calculated with the aid of a numerical code tracing charged particles in the Earth's magnetic field. By comparing the cutoff value with that measured by the LAT in different geomagnetic positions, we have obtained several calibration points between {approx}6 and {approx}13 GeV with an estimated uncertainty of {approx}2%. An energy calibration with such high accuracy reduces the systematic uncertainty in LAT measurements of, for example, the spectral cutoff in the emission from gamma ray pulsars.

  14. Calibration of High Precision Robot Arm for the Crafting of Magnets for Use in Neutron Experiments

    Science.gov (United States)

    Riley, Benjamin; Crawford, Christopher

    2017-01-01

    The magnetic scalar potential can be used to design precision magnetic fields with surface currents in arbitrary geometry. We are using this technique to design holding field coils for spin transport of neutrons and 3He atoms into the measurement cell of the SNS EDM experiment. We construct holding field coils as three-dimensional printed circuits boards using a Staubli RX130 6-axis industrial robotic arm to etch the circuit. While the arm has a 35-micron repeatability position, the absolute accuracy depends on calibration of transformation matrices between each link, characterized by Denavit-Hartenberg parameters. After factors such as coordinate system degeneracies and free parameters are taken into account, there are 29 parameters that must be calibrated. The robot model, calibration method, and results are presented in this poster.

  15. Calibration and data validation of wireless sensor network

    Science.gov (United States)

    Zhang, Jialin; Liu, Qiang; Li, Xiuhong; Niu, Hailin; Cai, Erli; Chang, Chongyan

    2015-12-01

    Soil moisture is an important parameter in the study of agriculture, ecology and carbon cycle. However, it has great difficulties to retrieve soil moisture content using remote sensing techniques. Even, field measurements can hardly reflect the spatial variation of soil moisture, due to the tremendous heterogeneity in its spatial distribution. Wireless Sensor Network (WSN), as a new technology for ground data collection, has been gradually applied to various fields. This novel technique has great advantages in monitoring soil moisture content, obtaining the soil moisture data in real time from multiple sites and different depths. Taking Huailai remote sensing comprehensive experimental station of Chinese Academy of Sciences for example, this paper introduces the calibration and data validation of soil moisture wireless sensor network. Oven drying method is used to calibrate the soil moisture sensor EC-5. The analysis indicates that the data measured by EC-5 had fairly well accuracy, so that the further calibration is not necessary. Data validation experiments had been taken from three aspects: data validity verification, temporal and spatial validation. It is clear to see that WSN data reveals the changes of soil moisture both in spatial domain and in different depths. Although the soil moisture data measured by WSN still do not have enough absolute accuracy, its continuous real-time data can clearly reflect the temporal and spatial relative variation, and the wide installation of sensors enables the data be obtained by the large amount, which was practically unavailable before.

  16. Radiation Calibration Measurements

    International Nuclear Information System (INIS)

    Omondi, C.

    2017-01-01

    KEBS Radiation Dosimetry mandate are: Custodian of Kenya Standards on Ionizing radiation, Ensure traceability to International System (SI ) and Calibration radiation equipment. RAF 8/040 on Radioisotope applications for troubleshooting and optimizing industrial process established Radiotracer Laboratory objective is to introduce and implement radiotracer technique for problem solving of industrial challenges. Gamma ray scanning technique applied is to Locate blockages, Locate liquid in vapor lines, Locate areas of lost refractory or lining in a pipe and Measure flowing densities. Equipment used for diagnostic and radiation protection must be calibrated to ensure Accuracy and Traceability

  17. The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF.

    Science.gov (United States)

    Casey, D T; Frenje, J A; Johnson, M Gatu; Séguin, F H; Li, C K; Petrasso, R D; Glebov, V Yu; Katz, J; Magoon, J; Meyerhofer, D D; Sangster, T C; Shoup, M; Ulreich, J; Ashabranner, R C; Bionta, R M; Carpenter, A C; Felker, B; Khater, H Y; LePape, S; MacKinnon, A; McKernan, M A; Moran, M; Rygg, J R; Yeoman, M F; Zacharias, R; Leeper, R J; Fletcher, K; Farrell, M; Jasion, D; Kilkenny, J; Paguio, R

    2013-04-01

    The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, ion-temperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describes ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF.

  18. Thermoluminescence dating (TL-Dating): an absolute method for archeological dating of ceramic base materials

    International Nuclear Information System (INIS)

    Wan Saffiey Wan Abdullah

    2004-01-01

    Thermoluminescence dating is one of the known techniques that have been established in many laboratories across the regions. This technique is capable to date the archeological ceramic base materials and provides an absolute measurement with an accuracy of 5%. The study involves the dating of ceramic clay from historical site at Sungai Mas, Kuala Muda, Kedah. Pieces of broken poetry of archeological sample excavated by the Museum Department and Antiquity (JM4) have been dated using the TLD techniques at MINT laboratory. A TLD dosemeter of LiF chips is used for the background and sample dose measurement. The preparation of sample and the calibration techniques for the estimation of palaedose or dose presented in the sample since distant past is established. Results indicate that the samples are in the era of civilization from 200BP to 1600BP. Error factors associated in the measurement procedures are also discussed

  19. Uncertainty Evaluations of the CRCS In-orbit Field Radiometric Calibration Methods for Thermal Infrared Channels of FENGYUN Meteorological Satellites

    Science.gov (United States)

    Zhang, Y.; Rong, Z.; Min, M.; Hao, X.; Yang, H.

    2017-12-01

    Meteorological satellites have become an irreplaceable weather and ocean-observing tool in China. These satellites are used to monitor natural disasters and improve the efficiency of many sectors of Chinese national economy. It is impossible to ignore the space-derived data in the fields of meteorology, hydrology, and agriculture, as well as disaster monitoring in China, a large agricultural country. For this reason, China is making a sustained effort to build and enhance its meteorological observing system and application system. The first Chinese polar-orbiting weather satellite was launched in 1988. Since then China has launched 14 meteorological satellites, 7 of which are sun synchronous and 7 of which are geostationary satellites; China will continue its two types of meteorological satellite programs. In order to achieve the in-orbit absolute radiometric calibration of the operational meteorological satellites' thermal infrared channels, China radiometric calibration sites (CRCS) established a set of in-orbit field absolute radiometric calibration methods (FCM) for thermal infrared channels (TIR) and the uncertainty of this method was evaluated and analyzed based on TERRA/AQUA MODIS observations. Comparisons between the MODIS at pupil brightness temperatures (BTs) and the simulated BTs at the top of atmosphere using radiative transfer model (RTM) based on field measurements showed that the accuracy of the current in-orbit field absolute radiometric calibration methods was better than 1.00K (@300K, K=1) in thermal infrared channels. Therefore, the current CRCS field calibration method for TIR channels applied to Chinese metrological satellites was with favorable calibration accuracy: for 10.5-11.5µm channel was better than 0.75K (@300K, K=1) and for 11.5-12.5µm channel was better than 0.85K (@300K, K=1).

  20. Absolute risk, absolute risk reduction and relative risk

    Directory of Open Access Journals (Sweden)

    Jose Andres Calvache

    2012-12-01

    Full Text Available This article illustrates the epidemiological concepts of absolute risk, absolute risk reduction and relative risk through a clinical example. In addition, it emphasizes the usefulness of these concepts in clinical practice, clinical research and health decision-making process.

  1. Scanner calibration revisited

    Directory of Open Access Journals (Sweden)

    Pozhitkov Alexander E

    2010-07-01

    Full Text Available Abstract Background Calibration of a microarray scanner is critical for accurate interpretation of microarray results. Shi et al. (BMC Bioinformatics, 2005, 6, Art. No. S11 Suppl. 2. reported usage of a Full Moon BioSystems slide for calibration. Inspired by the Shi et al. work, we have calibrated microarray scanners in our previous research. We were puzzled however, that most of the signal intensities from a biological sample fell below the sensitivity threshold level determined by the calibration slide. This conundrum led us to re-investigate the quality of calibration provided by the Full Moon BioSystems slide as well as the accuracy of the analysis performed by Shi et al. Methods Signal intensities were recorded on three different microarray scanners at various photomultiplier gain levels using the same calibration slide from Full Moon BioSystems. Data analysis was conducted on raw signal intensities without normalization or transformation of any kind. Weighted least-squares method was used to fit the data. Results We found that initial analysis performed by Shi et al. did not take into account autofluorescence of the Full Moon BioSystems slide, which led to a grossly distorted microarray scanner response. Our analysis revealed that a power-law function, which is explicitly accounting for the slide autofluorescence, perfectly described a relationship between signal intensities and fluorophore quantities. Conclusions Microarray scanners respond in a much less distorted fashion than was reported by Shi et al. Full Moon BioSystems calibration slides are inadequate for performing calibration. We recommend against using these slides.

  2. 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.

  3. Calibration methods for the Hargreaves-Samani equation

    Directory of Open Access Journals (Sweden)

    Lucas Borges Ferreira

    Full Text Available ABSTRACT The estimation of the reference evapotranspiration is an important factor for hydrological studies, design and management of irrigation systems, among others. The Penman Monteith equation presents high precision and accuracy in the estimation of this variable. However, its use becomes limited due to the large number of required meteorological data. In this context, the Hargreaves-Samani equation could be used as alternative, although, for a better performance a local calibration is required. Thus, the aim was to compare the calibration process of the Hargreaves-Samani equation by linear regression, by adjustment of the coefficients (A and B and exponent (C of the equation and by combinations of the two previous alternatives. Daily data from 6 weather stations, located in the state of Minas Gerais, from the period 1997 to 2016 were used. The calibration of the Hargreaves-Samani equation was performed in five ways: calibration by linear regression, adjustment of parameter “A”, adjustment of parameters “A” and “C”, adjustment of parameters “A”, “B” and “C” and adjustment of parameters “A”, “B” and “C” followed by calibration by linear regression. The performances of the models were evaluated based on the statistical indicators mean absolute error, mean bias error, Willmott’s index of agreement, correlation coefficient and performance index. All the studied methodologies promoted better estimations of reference evapotranspiration. The simultaneous adjustment of the empirical parameters “A”, “B” and “C” was the best alternative for calibration of the Hargreaves-Samani equation.

  4. 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....

  5. ZY3-02 Laser Altimeter On-orbit Geometrical Calibration and Test

    Directory of Open Access Journals (Sweden)

    TANG Xinming

    2017-06-01

    Full Text Available ZY3-02 is the first satellite equipped with a laser altimeter for earth observation in China .This laser altimeter is an experimental payload for land elevation measurement experiment. The ranging and pointing bias of the laser altimeter would change due to the launch vibration, the space environment difference or other factors, and that could bring plane and elevation errors of laser altimeter. In this paper, we propose an on-orbit geometric calibration method using a ground-based electro-optical detection system based on the analysis of ZY3-02 laser altimeter characteristic, and this method constructs the rigorous geometric calibration model, which consider the pointing and ranging bias as unknown systematic errors, and the unknown parameters are calibrated with laser spot's location captured by laser detectors and the minimum ranging error principle. With the ALOS-DSM data as reference, the elevation accuracy of the laser altimeter can be improved from 100~150 meters before calibration to 2~3 meters after calibration when the terrain slope is less than 2 degree. With several ground control points obtained with RTK in laser footprint for validation, the absolute elevation precision of laser altimeter in the flat area can reach about 1 meter after the calibration. The test results demonstrated the effectiveness and feasibility of the proposed method.

  6. Calibration of Nanopositioning Stages

    Directory of Open Access Journals (Sweden)

    Ning Tan

    2015-12-01

    Full Text Available Accuracy is one of the most important criteria for the performance evaluation of micro- and nanorobots or systems. Nanopositioning stages are used to achieve the high positioning resolution and accuracy for a wide and growing scope of applications. However, their positioning accuracy and repeatability are not well known and difficult to guarantee, which induces many drawbacks for many applications. For example, in the mechanical characterisation of biological samples, it is difficult to perform several cycles in a repeatable way so as not to induce negative influences on the study. It also prevents one from controlling accurately a tool with respect to a sample without adding additional sensors for closed loop control. This paper aims at quantifying the positioning repeatability and accuracy based on the ISO 9283:1998 standard, and analyzing factors influencing positioning accuracy onto a case study of 1-DoF (Degree-of-Freedom nanopositioning stage. The influence of thermal drift is notably quantified. Performances improvement of the nanopositioning stage are then investigated through robot calibration (i.e., open-loop approach. Two models (static and adaptive models are proposed to compensate for both geometric errors and thermal drift. Validation experiments are conducted over a long period (several days showing that the accuracy of the stage is improved from typical micrometer range to 400 nm using the static model and even down to 100 nm using the adaptive model. In addition, we extend the 1-DoF calibration to multi-DoF with a case study of a 2-DoF nanopositioning robot. Results demonstrate that the model efficiently improved the 2D accuracy from 1400 nm to 200 nm.

  7. Accuracy of magnetic resonance based susceptibility measurements

    Science.gov (United States)

    Erdevig, Hannah E.; Russek, Stephen E.; Carnicka, Slavka; Stupic, Karl F.; Keenan, Kathryn E.

    2017-05-01

    Magnetic Resonance Imaging (MRI) is increasingly used to map the magnetic susceptibility of tissue to identify cerebral microbleeds associated with traumatic brain injury and pathological iron deposits associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease. Accurate measurements of susceptibility are important for determining oxygen and iron content in blood vessels and brain tissue for use in noninvasive clinical diagnosis and treatment assessments. Induced magnetic fields with amplitude on the order of 100 nT, can be detected using MRI phase images. The induced field distributions can then be inverted to obtain quantitative susceptibility maps. The focus of this research was to determine the accuracy of MRI-based susceptibility measurements using simple phantom geometries and to compare the susceptibility measurements with magnetometry measurements where SI-traceable standards are available. The susceptibilities of paramagnetic salt solutions in cylindrical containers were measured as a function of orientation relative to the static MRI field. The observed induced fields as a function of orientation of the cylinder were in good agreement with simple models. The MRI susceptibility measurements were compared with SQUID magnetometry using NIST-traceable standards. MRI can accurately measure relative magnetic susceptibilities while SQUID magnetometry measures absolute magnetic susceptibility. Given the accuracy of moment measurements of tissue mimicking samples, and the need to look at small differences in tissue properties, the use of existing NIST standard reference materials to calibrate MRI reference structures is problematic and better reference materials are required.

  8. Absolute nondestructive quantitative determination of uranium in special nuclear materials

    International Nuclear Information System (INIS)

    Dragnev, T.; Damyanov, B.; Grozev, G.; Karamanova, J.

    1985-01-01

    An absolute nondestructive method for quantitative measurement of uranium concentration and enrichment in special nuclear materials is proposed. The method uses intrinsic calibration and portable instrumentation and the particularly suitable for IAEA safequards applications. The intrinsic calibration accumulates the positive experience of the previous measurements and the results will be continuously improving. It is possible to measure standards in laboratories and use the results for analysis at different time and places. The tests show a good agreement with known classical methods and better results in some cases

  9. The Advanced LIGO photon calibrators.

    Science.gov (United States)

    Karki, S; Tuyenbayev, D; Kandhasamy, S; Abbott, B P; Abbott, T D; Anders, E H; Berliner, J; Betzwieser, J; Cahillane, C; Canete, L; Conley, C; Daveloza, H P; De Lillo, N; Gleason, J R; Goetz, E; Izumi, K; Kissel, J S; Mendell, G; Quetschke, V; Rodruck, M; Sachdev, S; Sadecki, T; Schwinberg, P B; Sottile, A; Wade, M; Weinstein, A J; West, M; Savage, R L

    2016-11-01

    The two interferometers of the Laser Interferometry Gravitational-wave Observatory (LIGO) recently detected gravitational waves from the mergers of binary black hole systems. Accurate calibration of the output of these detectors was crucial for the observation of these events and the extraction of parameters of the sources. The principal tools used to calibrate the responses of the second-generation (Advanced) LIGO detectors to gravitational waves are systems based on radiation pressure and referred to as photon calibrators. These systems, which were completely redesigned for Advanced LIGO, include several significant upgrades that enable them to meet the calibration requirements of second-generation gravitational wave detectors in the new era of gravitational-wave astronomy. We report on the design, implementation, and operation of these Advanced LIGO photon calibrators that are currently providing fiducial displacements on the order of 10 -18 m/Hz with accuracy and precision of better than 1%.

  10. The Advanced LIGO photon calibrators

    Science.gov (United States)

    Karki, S.; Tuyenbayev, D.; Kandhasamy, S.; Abbott, B. P.; Abbott, T. D.; Anders, E. H.; Berliner, J.; Betzwieser, J.; Cahillane, C.; Canete, L.; Conley, C.; Daveloza, H. P.; De Lillo, N.; Gleason, J. R.; Goetz, E.; Izumi, K.; Kissel, J. S.; Mendell, G.; Quetschke, V.; Rodruck, M.; Sachdev, S.; Sadecki, T.; Schwinberg, P. B.; Sottile, A.; Wade, M.; Weinstein, A. J.; West, M.; Savage, R. L.

    2016-11-01

    The two interferometers of the Laser Interferometry Gravitational-wave Observatory (LIGO) recently detected gravitational waves from the mergers of binary black hole systems. Accurate calibration of the output of these detectors was crucial for the observation of these events and the extraction of parameters of the sources. The principal tools used to calibrate the responses of the second-generation (Advanced) LIGO detectors to gravitational waves are systems based on radiation pressure and referred to as photon calibrators. These systems, which were completely redesigned for Advanced LIGO, include several significant upgrades that enable them to meet the calibration requirements of second-generation gravitational wave detectors in the new era of gravitational-wave astronomy. We report on the design, implementation, and operation of these Advanced LIGO photon calibrators that are currently providing fiducial displacements on the order of 1 0-18m /√{Hz } with accuracy and precision of better than 1%.

  11. Calibration of film radiochromic EBT2 for sources of I-125 encapsulated

    International Nuclear Information System (INIS)

    Huerga Cabrerizo, C.; Luquero Llopis, N.; Torre Hernandez, I. de la; Ferrer Garcia, C.; Corredoira silva, E.; Serrada Hierro, A.

    2013-01-01

    This paper determines the calibration curve in absolute dose for sources of I-125 encapsulated to estimate its uncertainty. In order to assess energy dependence is compared with the obtained for an accelerator of 6MV calibration curve. (Author)

  12. 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

  13. Immune Algorithm Complex Method for Transducer Calibration

    Directory of Open Access Journals (Sweden)

    YU Jiangming

    2014-08-01

    Full Text Available As a key link in engineering test tasks, the transducer calibration has significant influence on accuracy and reliability of test results. Because of unknown and complex nonlinear characteristics, conventional method can’t achieve satisfactory accuracy. An Immune algorithm complex modeling approach is proposed, and the simulated studies on the calibration of third multiple output transducers is made respectively by use of the developed complex modeling. The simulated and experimental results show that the Immune algorithm complex modeling approach can improve significantly calibration precision comparison with traditional calibration methods.

  14. Calibration issues for neutron diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Sadler, G.J. [JET Joint Undertaking, Abingdon (United Kingdom); Adams, J.M. [AEA Technology, Harwell (United Kingdom); Barnes, C.W. [Los Alamos National Lab., NM (United States)] [and others

    1997-12-01

    The performance of diagnostic systems are limited by their weakest constituents, including their calibration issues. Neutron diagnostics are notorious for problems encountered while determining their absolute calibrations, due mainly to the nature of the neutron transport problem. In order to facilitate the determination of an accurate and precise calibration, the diagnostic design should be such as to minimize the scattered neutron flux. ITER will use a comprehensive set of neutron diagnostics--comprising radial and vertical neutron cameras, neutron spectrometers, a neutron activation system and internal and external fission chambers--to provide accurate measurements of fusion power and power densities as a function of time. The calibration of such an important diagnostic system merits careful consideration. Some thoughts have already been given to this subject during the conceptual design phase in relation to the time-integrated neutron activation and time-dependent neutron yield monitors. However, no overall calibration strategy has been worked out so far. This paper represents a first attempt to address this vital issue. Experience gained from present large tokamaks (JET, TFTR and JT60U) and proposals for ITER are reviewed. The need to use a 14-MeV neutron generator as opposed to radioactive sources for in-situ calibration of D-T diagnostics will be stressed. It is clear that the overall absolute determination of fusion power will have to rely on a combination of nuclear measuring techniques, for which the provision of accurate and independent calibrations will constitute an ongoing process as ITER moves from one phase of operation to the next.

  15. An improved generalized Newton method for absolute value equations.

    Science.gov (United States)

    Feng, Jingmei; Liu, Sanyang

    2016-01-01

    In this paper, we suggest and analyze an improved generalized Newton method for solving the NP-hard absolute value equations [Formula: see text] when the singular values of A exceed 1. We show that the global and local quadratic convergence of the proposed method. Numerical experiments show the efficiency of the method and the high accuracy of calculation.

  16. A calculation and uncertainty evaluation method for the effective area of a piston rod used in quasi-static pressure calibration

    Science.gov (United States)

    Gu, Tingwei; Kong, Deren; Shang, Fei; Chen, Jing

    2018-04-01

    This paper describes the merits and demerits of different sensors for measuring propellant gas pressure, the applicable range of the frequently used dynamic pressure calibration methods, and the working principle of absolute quasi-static pressure calibration based on the drop-weight device. The main factors affecting the accuracy of pressure calibration are analyzed from two aspects of the force sensor and the piston area. To calculate the effective area of the piston rod and evaluate the uncertainty between the force sensor and the corresponding peak pressure in the absolute quasi-static pressure calibration process, a method for solving these problems based on the least squares principle is proposed. According to the relevant quasi-static pressure calibration experimental data, the least squares fitting model between the peak force and the peak pressure, and the effective area of the piston rod and its measurement uncertainty, are obtained. The fitting model is tested by an additional group of experiments, and the peak pressure obtained by the existing high-precision comparison calibration method is taken as the reference value. The test results show that the peak pressure obtained by the least squares fitting model is closer to the reference value than the one directly calculated by the cross-sectional area of the piston rod. When the peak pressure is higher than 150 MPa, the percentage difference is less than 0.71%, which can meet the requirements of practical application.

  17. In-orbit Calibration and Local Gravity Field Continuation Problem

    Science.gov (United States)

    Pail, R.

    In the course of the GOCE data processing many calibration tasks have to be per- formed. Towards the final part of the data stream, an absolute calibration and vali- dation of the gradiometer signal is required. One of the most promising methods for such an in-orbit calibration is the use of well-surveyed areas on the Earth's surface, where the accuracy of the known gravity field information is high enough to meet the mission requirements. For this purpose ground gravity data have to be continued upward to the GOCE satellite altitude of approximately 250 km, where a comparison with the actual observations is performed. Since there are only very few regions on the globe which fulfil the accuracy requirements, the corresponding gravity information is extremely locally bounded, dismissing standard global continuation strategies and simultaneously resulting in edge effect and windowing problems. Based on a synthetic gravity test environment ­ providing in addition to statistical er- ror information also absolute error estimates ­ several upward continuation methods, e.g. least squares collocation, equivalent source techniques using point masses or area density distributions defined on a spherical surface section, are described, assessed and compared. It turns out that all these strictly local approaches fail to work suffi- ciently accurate. Consequently, a combined solution strategy is proposed, supporting the high-quality gravity field information within the well-surveyed test area with a low accuracy, but globally defined Earth model. Under quite realistic assumptions the upward continuation is performed with rms errors of gravity gradients in the order of 1 mE. The most crucial limiting factor of this method is spectral leakage in the course of an adequate representation of the initial gravity information. We will particularly focus on the consequences and effects of the different approaches on the accuracy of GOCE level 1b and 2 products. In order to demonstrate

  18. A Calibration Method for A Linear Structured Light System with Three Collinear Points

    Directory of Open Access Journals (Sweden)

    Yan Liu

    2011-12-01

    Full Text Available A calibration method to calibrate both the camera intrinsic parameters and the structured light projector based on three collinear points with any known distance is presented. First, fix one point of the target and move it in the camera field of view with unknown viewpoint at least six times. Next, use camera to obtain the image of the points so as to identify the camera intrinsic parameters. Then, move the target in the structure light plane at least twice. Using the calibrated camera obtains the images of the three points and adopts the principle of triangulation to work out the coordinates of the calibration points in the camera coordinate system. Finally, employ the random sample consensus algorithm to eliminate the outlier and adopt the genetic algorithm for system identification to find the coefficients of the structured light plane. The average absolute error and the average relative error of the segment measurement with this structured light system are 0.13 mm and 0.04%, respectively. Those show that the measuring accuracy of this system achieves the requirements of the basic error limit. Comparison results show that the measurement accuracy of our method is superior to the other method for the same targets.

  19. Further calibration of the Swift ultraviolet/optical telescope

    Science.gov (United States)

    Breeveld, A. A.; Curran, P. A.; Hoversten, E. A.; Koch, S.; Landsman, W.; Marshall, F. E.; Page, M. J.; Poole, T. S.; Roming, P.; Smith, P. J.; Still, M.; Yershov, V.; Blustin, A. J.; Brown, P. J.; Gronwall, C.; Holland, S. T.; Kuin, N. P. M.; McGowan, K.; Rosen, S.; Boyd, P.; Broos, P.; Carter, M.; Chester, M. M.; Hancock, B.; Huckle, H.; Immler, S.; Ivanushkina, M.; Kennedy, T.; Mason, K. O.; Morgan, A. N.; Oates, S.; de Pasquale, M.; Schady, P.; Siegel, M.; vanden Berk, D.

    2010-08-01

    The Ultraviolet/Optical Telescope (UVOT) is one of three instruments onboard the Swift observatory. The photometric calibration has been published, and this paper follows up with details on other aspects of the calibration including a measurement of the point spread function with an assessment of the orbital variation and the effect on photometry. A correction for large-scale variations in sensitivity over the field of view is described, as well as a model of the coincidence loss which is used to assess the coincidence correction in extended regions. We have provided a correction for the detector distortion and measured the resulting internal astrometric accuracy of the UVOT, also giving the absolute accuracy with respect to the International Celestial Reference System. We have compiled statistics on the background count rates, and discuss the sources of the background, including instrumental scattered light. In each case, we describe any impact on UVOT measurements, whether any correction is applied in the standard pipeline data processing or whether further steps are recommended.

  20. SDSS-IV/MaNGA: SPECTROPHOTOMETRIC CALIBRATION TECHNIQUE

    International Nuclear Information System (INIS)

    Yan, Renbin; Sánchez-Gallego, José R.; Tremonti, Christy; Bershady, Matthew A.; Eigenbrot, Arthur; Wake, David A.; Law, David R.; Schlegel, David J.; Bundy, Kevin; Drory, Niv; MacDonald, Nicholas; Bizyaev, Dmitry; Blanc, Guillermo A.; Blanton, Michael R.; Hogg, David W.; Cherinka, Brian; Gunn, James E.; Harding, Paul; Sánchez, Sebastian F.

    2016-01-01

    Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), one of three core programs in the Sloan Digital Sky Survey-IV, is an integral-field spectroscopic survey of roughly 10,000 nearby galaxies. It employs dithered observations using 17 hexagonal bundles of 2″ fibers to obtain resolved spectroscopy over a wide wavelength range of 3600–10300 Å. To map the internal variations within each galaxy, we need to perform accurate spectral surface photometry, which is to calibrate the specific intensity at every spatial location sampled by each individual aperture element of the integral field unit. The calibration must correct only for the flux loss due to atmospheric throughput and the instrument response, but not for losses due to the finite geometry of the fiber aperture. This requires the use of standard star measurements to strictly separate these two flux loss factors (throughput versus geometry), a difficult challenge with standard single-fiber spectroscopy techniques due to various practical limitations. Therefore, we developed a technique for spectral surface photometry using multiple small fiber-bundles targeting standard stars simultaneously with galaxy observations. We discuss the principles of our approach and how they compare to previous efforts, and we demonstrate the precision and accuracy achieved. MaNGA's relative calibration between the wavelengths of Hα and Hβ has an rms of 1.7%, while that between [N ii] λ6583 and [O ii] λ3727 has an rms of 4.7%. Using extinction-corrected star formation rates and gas-phase metallicities as an illustration, this level of precision guarantees that flux calibration errors will be sub-dominant when estimating these quantities. The absolute calibration is better than 5% for more than 89% of MaNGA's wavelength range

  1. SDSS-IV/MaNGA: SPECTROPHOTOMETRIC CALIBRATION TECHNIQUE

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Renbin; Sánchez-Gallego, José R. [Department of Physics and Astronomy, University of Kentucky, 505 Rose St., Lexington, KY 40506-0057 (United States); Tremonti, Christy; Bershady, Matthew A.; Eigenbrot, Arthur; Wake, David A. [Department of Astronomy, University of Winsconsin-Madison, 475 N. Charter Street, Madison, WI 53706-1582 (United States); Law, David R. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Schlegel, David J. [Physics Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8160 (United States); Bundy, Kevin [Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Drory, Niv [McDonald Observatory, Department of Astronomy, University of Texas at Austin, 1 University Station, Austin, TX 78712-0259 (United States); MacDonald, Nicholas [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Bizyaev, Dmitry [Apache Point Observatory, P.O. Box 59, sunspot, NM 88349 (United States); Blanc, Guillermo A. [Departamento de Astronomía, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago (Chile); Blanton, Michael R.; Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Cherinka, Brian [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada); Gunn, James E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Harding, Paul [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States); Sánchez, Sebastian F., E-mail: yanrenbin@uky.edu [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, A.P. 70-264, 04510 Mexico D.F. (Mexico); and others

    2016-01-15

    Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), one of three core programs in the Sloan Digital Sky Survey-IV, is an integral-field spectroscopic survey of roughly 10,000 nearby galaxies. It employs dithered observations using 17 hexagonal bundles of 2″ fibers to obtain resolved spectroscopy over a wide wavelength range of 3600–10300 Å. To map the internal variations within each galaxy, we need to perform accurate spectral surface photometry, which is to calibrate the specific intensity at every spatial location sampled by each individual aperture element of the integral field unit. The calibration must correct only for the flux loss due to atmospheric throughput and the instrument response, but not for losses due to the finite geometry of the fiber aperture. This requires the use of standard star measurements to strictly separate these two flux loss factors (throughput versus geometry), a difficult challenge with standard single-fiber spectroscopy techniques due to various practical limitations. Therefore, we developed a technique for spectral surface photometry using multiple small fiber-bundles targeting standard stars simultaneously with galaxy observations. We discuss the principles of our approach and how they compare to previous efforts, and we demonstrate the precision and accuracy achieved. MaNGA's relative calibration between the wavelengths of Hα and Hβ has an rms of 1.7%, while that between [N ii] λ6583 and [O ii] λ3727 has an rms of 4.7%. Using extinction-corrected star formation rates and gas-phase metallicities as an illustration, this level of precision guarantees that flux calibration errors will be sub-dominant when estimating these quantities. The absolute calibration is better than 5% for more than 89% of MaNGA's wavelength range.

  2. A kinetic-based sigmoidal model for the polymerase chain reaction and its application to high-capacity absolute quantitative real-time PCR

    Directory of Open Access Journals (Sweden)

    Stewart Don

    2008-05-01

    Full Text Available Abstract Background Based upon defining a common reference point, current real-time quantitative PCR technologies compare relative differences in amplification profile position. As such, absolute quantification requires construction of target-specific standard curves that are highly resource intensive and prone to introducing quantitative errors. Sigmoidal modeling using nonlinear regression has previously demonstrated that absolute quantification can be accomplished without standard curves; however, quantitative errors caused by distortions within the plateau phase have impeded effective implementation of this alternative approach. Results Recognition that amplification rate is linearly correlated to amplicon quantity led to the derivation of two sigmoid functions that allow target quantification via linear regression analysis. In addition to circumventing quantitative errors produced by plateau distortions, this approach allows the amplification efficiency within individual amplification reactions to be determined. Absolute quantification is accomplished by first converting individual fluorescence readings into target quantity expressed in fluorescence units, followed by conversion into the number of target molecules via optical calibration. Founded upon expressing reaction fluorescence in relation to amplicon DNA mass, a seminal element of this study was to implement optical calibration using lambda gDNA as a universal quantitative standard. Not only does this eliminate the need to prepare target-specific quantitative standards, it relegates establishment of quantitative scale to a single, highly defined entity. The quantitative competency of this approach was assessed by exploiting "limiting dilution assay" for absolute quantification, which provided an independent gold standard from which to verify quantitative accuracy. This yielded substantive corroborating evidence that absolute accuracies of ± 25% can be routinely achieved. Comparison

  3. 40Ar/39Ar age calibration against counted annuallayers

    DEFF Research Database (Denmark)

    Storey, Michael; Stecher, Ole

    2008-01-01

    The 40Ar/39Ar method, based on the decay of the naturally occurring radioactive isotope 40K, is capable of producing ages with precision better than ± 0.1 %. However, accuracy is limited to no better than 1 % mainly due to the relatively large uncertainty in the 40K decay constants. One approach...... worth exploring for an improved absolute age basis for the 40Ar/39Ar system is through cross-calibration with counted annual layers (e.g. tree rings, varves and ice cores). North Atlantic Ash Zone (NAAZ) II is found within the dated part of the annual Greenland ice core record. NAAZ II has been...... correlated to the Icelandic peralkaline rhyolitic Thorsmörk ignimbrite. We will present preliminary 40Ar/39Ar results on the age of this eruption...

  4. Absolute marine gravimetry with matter-wave interferometry.

    Science.gov (United States)

    Bidel, Y; Zahzam, N; Blanchard, C; Bonnin, A; Cadoret, M; Bresson, A; Rouxel, D; Lequentrec-Lalancette, M F

    2018-02-12

    Measuring gravity from an aircraft or a ship is essential in geodesy, geophysics, mineral and hydrocarbon exploration, and navigation. Today, only relative sensors are available for onboard gravimetry. This is a major drawback because of the calibration and drift estimation procedures which lead to important operational constraints. Atom interferometry is a promising technology to obtain onboard absolute gravimeter. But, despite high performances obtained in static condition, no precise measurements were reported in dynamic. Here, we present absolute gravity measurements from a ship with a sensor based on atom interferometry. Despite rough sea conditions, we obtained precision below 10 -5  m s -2 . The atom gravimeter was also compared with a commercial spring gravimeter and showed better performances. This demonstration opens the way to the next generation of inertial sensors (accelerometer, gyroscope) based on atom interferometry which should provide high-precision absolute measurements from a moving platform.

  5. Commodity-Free Calibration

    Science.gov (United States)

    2008-01-01

    Commodity-free calibration is a reaction rate calibration technique that does not require the addition of any commodities. This technique is a specific form of the reaction rate technique, where all of the necessary reactants, other than the sample being analyzed, are either inherent in the analyzing system or specifically added or provided to the system for a reason other than calibration. After introduction, the component of interest is exposed to other reactants or flow paths already present in the system. The instrument detector records one of the following to determine the rate of reaction: the increase in the response of the reaction product, a decrease in the signal of the analyte response, or a decrease in the signal from the inherent reactant. With this data, the initial concentration of the analyte is calculated. This type of system can analyze and calibrate simultaneously, reduce the risk of false positives and exposure to toxic vapors, and improve accuracy. Moreover, having an excess of the reactant already present in the system eliminates the need to add commodities, which further reduces cost, logistic problems, and potential contamination. Also, the calculations involved can be simplified by comparison to those of the reaction rate technique. We conducted tests with hypergols as an initial investigation into the feasiblility of the technique.

  6. High Accuracy Beam Current Monitor System for CEBAF'S Experimental Hall A

    International Nuclear Information System (INIS)

    J. Denard; A. Saha; G. Lavessiere

    2001-01-01

    CEBAF accelerator delivers continuous wave (CW) electron beams to three experimental Halls. In Hall A, all experiments require continuous, non-invasive current measurements and a few experiments require an absolute accuracy of 0.2 % in the current range from 1 to 180 (micro)A. A Parametric Current Transformer (PCT), manufactured by Bergoz, has an accurate and stable sensitivity of 4 (micro)A/V but its offset drifts at the muA level over time preclude its direct use for continuous measurements. Two cavity monitors are calibrated against the PCT with at least 50 (micro)A of beam current. The calibration procedure suppresses the error due to PCT's offset drifts by turning the beam on and off, which is invasive to the experiment. One of the goals of the system is to minimize the calibration time without compromising the measurement's accuracy. The linearity of the cavity monitors is a critical parameter for transferring the accurate calibration done at high currents over the whole dynamic range. The method for measuring accurately the linearity is described

  7. Simulation and analysis of spectroscopic filter of rotational Raman lidar for absolute measurement of atmospheric temperature

    Science.gov (United States)

    Li, Qimeng; Li, Shichun; Hu, Xianglong; Zhao, Jing; Xin, Wenhui; Song, Yuehui; Hua, Dengxin

    2018-01-01

    The absolute measurement technique for atmospheric temperature can avoid the calibration process and improve the measurement accuracy. To achieve the rotational Raman temperature lidar of absolute measurement, the two-stage parallel multi-channel spectroscopic filter combined a first-order blazed grating with a fiber Bragg grating is designed and its performance is tested. The parameters and the optical path structure of the core cascaded-device (micron-level fiber array) are optimized, the optical path of the primary spectroscope is simulated and the maximum centrifugal distortion of the rotational Raman spectrum is approximately 0.0031 nm, the centrifugal ratio of 0.69%. The experimental results show that the channel coefficients of the primary spectroscope are 0.67, 0.91, 0.67, 0.75, 0.82, 0.63, 0.87, 0.97, 0.89, 0.87 and 1 by using the twelfth channel as a reference and the average FWHM is about 0.44 nm. The maximum deviation between the experimental wavelength and the theoretical value is approximately 0.0398 nm, with the deviation degree of 8.86%. The effective suppression to elastic scattering signal are 30.6, 35.2, 37.1, 38.4, 36.8, 38.2, 41.0, 44.3, 44.0, 46.7 dB. That means, combined with the second spectroscope, the suppression at least is up to 65 dB. Therefore we can fine extract single rotational Raman line to achieve the absolute measurement technique.

  8. Prelaunch calibrations and on-orbit performance analysis of FY-2D SVISSR infrared channels

    Science.gov (United States)

    Zhang, Yong; Chen, Fuchun

    2014-10-01

    Meteorological satellites have become an irreplaceable weather and ocean-observing tool in China. These satellites are used to monitor natural disasters and improve the efficiency of many sectors of Chinese national economy. FY-2 series satellites are one of the key components of Chinese meteorological observing system and application system. In this paper, the operational satellite- FY-2D's infrared channels were focused and analyzed. The instruments' background was introduced briefly. The main payload SVISSR specifications were compared with its ancestral VISSR. The optical structure of the SVISSR was also expressed. FY-2D prelaunch calibrations methodology was introduced and the accuracies of the absolute radiometric calibration were analyzed. Some key optics on-orbit performance of FY-2D SVISSR were analyzed include onboard blackbody, cold FPA and detector noise level. All of these works show that FY- 2D's main payload SVISSR was in a healthy status.

  9. Model independent approach to the single photoelectron calibration of photomultiplier tubes

    Energy Technology Data Exchange (ETDEWEB)

    Saldanha, R.; Grandi, L.; Guardincerri, Y.; Wester, T.

    2017-08-01

    The accurate calibration of photomultiplier tubes is critical in a wide variety of applications in which it is necessary to know the absolute number of detected photons or precisely determine the resolution of the signal. Conventional calibration methods rely on fitting the photomultiplier response to a low intensity light source with analytical approximations to the single photoelectron distribution, often leading to biased estimates due to the inability to accurately model the full distribution, especially at low charge values. In this paper we present a simple statistical method to extract the relevant single photoelectron calibration parameters without making any assumptions about the underlying single photoelectron distribution. We illustrate the use of this method through the calibration of a Hamamatsu R11410 photomultiplier tube and study the accuracy and precision of the method using Monte Carlo simulations. The method is found to have significantly reduced bias compared to conventional methods and works under a wide range of light intensities, making it suitable for simultaneously calibrating large arrays of photomultiplier tubes.

  10. Precision and accuracy control of dose calibrator: CAPINTEC CRC 12 in laboratory for radiopharmacy of Nuclear Medicine Institute of Sucre, Bolivia; Control de precision y exactitud del calibrador de dosis: CAPINTEC CRC 12 del Laboratorio de Radiofarmacia del Instituto de Medicina Nuclear Sucre

    Energy Technology Data Exchange (ETDEWEB)

    Huanca Sardinas, E; Castro Sacci, O; Torrez Cabero, M; Vasquez Ibanez, M.R; Zambrana Zelada, AJ., E-mail: nuclear_sre@entelnet.bo, E-mail: ehuancasardinas@hotmail.com, E-mail: marcetorrez@hotmail.com, E-mail: maritavas@yahoo.es, E-mail: alfzambrana@gmail.com [Universidad Mayor Real y Pontifica de San Francisco Xavier de Chuquisaca, Sucre (Bolivia, Plurinational State of). Radiofarmacia - Instituto de Medicina Nuclear de Sucre. Hospital Santa Barbara

    2013-11-01

    The dose calibrator is one of the indispensable tools in radiopharmacy laboratories of a nuclear medicine department also is mandated to provide accurate readings. A very high doses produce unnecessary radiation exposure to the patient or a very low dose, prolong the acquisition time of the studies affecting the quality of the image. In the present work we did a retrospective analysis of the results of quality checks performed at precision accuracy of the Gauge CRC12 CAPINTEC dose calibrator over a period of 16 years, using sealed certified sources with low power, medium and high: Ba{sup 133} , Cs{sup 137} , Co{sup 60} and Co{sup 57}. The results showed that the lowest standard deviation value was 0.17 for Ba133, relative to Co{sup 57} of 2.97 in the control of accuracy. Accuracy over control values were also lower standard deviation for Ba{sup 133} 1.00, relative to Co{sup 57} 10.06. Being stated that the CRC12 CAPINTEC activimeter reliability is acceptable during the reporting period and under the conditions indicated. Therefore, we continue to make these quality control procedures and the professional must feel confident that the measurements obtained with it are reliable.

  11. Calibration of PMIS pavement performance prediction models.

    Science.gov (United States)

    2012-02-01

    Improve the accuracy of TxDOTs existing pavement performance prediction models through calibrating these models using actual field data obtained from the Pavement Management Information System (PMIS). : Ensure logical performance superiority patte...

  12. Iowa calibration of MEPDG performance prediction models.

    Science.gov (United States)

    2013-06-01

    This study aims to improve the accuracy of AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) pavement : performance predictions for Iowa pavement systems through local calibration of MEPDG prediction models. A total of 130 : representative p...

  13. New on-orbit geometric interior parameters self-calibration approach based on three-view stereoscopic images from high-resolution multi-TDI-CCD optical satellites.

    Science.gov (United States)

    Cheng, Yufeng; Wang, Mi; Jin, Shuying; He, Luxiao; Tian, Yuan

    2018-03-19

    To increase the field of view (FOV), combining multiple time-delayed and integrated charge-coupled devices (TDI-CCD) into the camera and the pushbroom imaging modality are traditionally used with high-resolution optical satellites. It is becoming increasingly labor- and cost-intensive to build and maintain a calibration field with high resolution and broad coverage. This paper introduces a simple and feasible on-orbit geometric self-calibration approach for high-resolution multi-TDI-CCD optical satellites based on three-view stereoscopic images. With the aid of the a priori geometric constraint of tie points in the triple-overlap regions of stereoscopic images, as well as tie points between adjacent single TDI-CCD images (STIs), high accuracy calibration of all TDI-CCD detectors can be achieved using a small number of absolute ground control points (GCPs) covering the selected primary STI. This method greatly reduces the demand on the calibration field and thus is more time-, effort- and cost-effective. Experimental results indicated that the proposed self-calibration approach is effective for increasing the relative internal accuracy without the limitations associated with using a traditional reference calibration field, which could have great significance for future super-high-resolution optical satellites.

  14. Development of absolute radiometric response functions for HyPlant & G-LiHT using SIRCUS Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this project is to provide absolute radiometric and cross-calibrated spectral characterizations for G-LiHT and HyPlant.  The objectives are: (i) to...

  15. System Design, Calibration and Performance Analysis of a Novel 360° Stereo Panoramic Mobile Mapping System

    Science.gov (United States)

    Blaser, S.; Nebiker, S.; Cavegn, S.

    2017-05-01

    Image-based mobile mapping systems enable the efficient acquisition of georeferenced image sequences, which can later be exploited in cloud-based 3D geoinformation services. In order to provide a 360° coverage with accurate 3D measuring capabilities, we present a novel 360° stereo panoramic camera configuration. By using two 360° panorama cameras tilted forward and backward in combination with conventional forward and backward looking stereo camera systems, we achieve a full 360° multi-stereo coverage. We furthermore developed a fully operational new mobile mapping system based on our proposed approach, which fulfils our high accuracy requirements. We successfully implemented a rigorous sensor and system calibration procedure, which allows calibrating all stereo systems with a superior accuracy compared to that of previous work. Our study delivered absolute 3D point accuracies in the range of 4 to 6 cm and relative accuracies of 3D distances in the range of 1 to 3 cm. These results were achieved in a challenging urban area. Furthermore, we automatically reconstructed a 3D city model of our study area by employing all captured and georeferenced mobile mapping imagery. The result is a very high detailed and almost complete 3D city model of the street environment.

  16. The PMA Catalogue: 420 million positions and absolute proper motions

    Science.gov (United States)

    Akhmetov, V. S.; Fedorov, P. N.; Velichko, A. B.; Shulga, V. M.

    2017-07-01

    We present a catalogue that contains about 420 million absolute proper motions of stars. It was derived from the combination of positions from Gaia DR1 and 2MASS, with a mean difference of epochs of about 15 yr. Most of the systematic zonal errors inherent in the 2MASS Catalogue were eliminated before deriving the absolute proper motions. The absolute calibration procedure (zero-pointing of the proper motions) was carried out using about 1.6 million positions of extragalactic sources. The mean formal error of the absolute calibration is less than 0.35 mas yr-1. The derived proper motions cover the whole celestial sphere without gaps for a range of stellar magnitudes from 8 to 21 mag. In the sky areas where the extragalactic sources are invisible (the avoidance zone), a dedicated procedure was used that transforms the relative proper motions into absolute ones. The rms error of proper motions depends on stellar magnitude and ranges from 2-5 mas yr-1 for stars with 10 mag < G < 17 mag to 5-10 mas yr-1 for faint ones. The present catalogue contains the Gaia DR1 positions of stars for the J2015 epoch. The system of the PMA proper motions does not depend on the systematic errors of the 2MASS positions, and in the range from 14 to 21 mag represents an independent realization of a quasi-inertial reference frame in the optical and near-infrared wavelength range. The Catalogue also contains stellar magnitudes taken from the Gaia DR1 and 2MASS catalogues. A comparison of the PMA proper motions of stars with similar data from certain recent catalogues has been undertaken.

  17. The CHEOPS calibration bench

    Science.gov (United States)

    Wildi, F.; Chazelas, B.; Deline, A.; Sarajlic, M.; Sordet, M.

    2017-09-01

    CHEOPS is an ESA Class S Mission aiming at the characterization of exoplanets through the precise measurement of their radius, using the transit method [1]. To achieve this goal, the payload is designed to be a high precision "absolute" photometer, looking at one star at a time. It will be able to cover la large fraction of the sky by repointing. Its launch is expected at the end of 2017 [2, this conference]. CHEOPS' main science is the measure of the transit of exoplanets of radius ranging from 1 to 6 Earth radii orbiting bright stars. The required photometric stability to reach this goal is of 20 ppm in 6 hours for a 9th magnitude star. The CHEOPS' only instrument is a Ritchey-Chretien style telescope with 300 mm effective aperture diameter, which provides a defocussed image of the target star on a single frame-transfer backside illuminated CCD detector cooled to -40°C and stabilized within 10 mK [2]. CHEOPS being in a LEO, it is equipped with a high performance baffle. The spacecraft platform provides a pointing stability of flat-fielding necessary In the rest of this article we will refer to the only CHEOPS instrument simply as "CHEOP" Its behavior will be calibrated thoroughly on the ground and only a small subset of the calibrations can be redone in flight. The main focuses of the calibrations are the photonic gain stability and sensibility to the environment variations and the Flat field that has to be known at a precision better than 0.1%.

  18. Convective blueshifts in the solar atmosphere. I. Absolute measurements with LARS of the spectral lines at 6302 Å

    Science.gov (United States)

    Löhner-Böttcher, J.; Schmidt, W.; Stief, F.; Steinmetz, T.; Holzwarth, R.

    2018-03-01

    Context. The solar convection manifests as granulation and intergranulation at the solar surface. In the photosphere, convective motions induce differential Doppler shifts to spectral lines. The observed convective blueshift varies across the solar disk. Aim. We focus on the impact of solar convection on the atmosphere and aim to resolve its velocity stratification in the photosphere. Methods: We performed high-resolution spectroscopic observations of the solar spectrum in the 6302 Å range with the Laser Absolute Reference Spectrograph at the Vacuum Tower Telescope. A laser frequency comb enabled the calibration of the spectra to an absolute wavelength scale with an accuracy of 1 m s-1. We systematically scanned the quiet Sun from the disk center to the limb at ten selected heliocentric positions. The analysis included 99 time sequences of up to 20 min in length. By means of ephemeris and reference corrections, we translated wavelength shifts into absolute line-of-sight velocities. A bisector analysis on the line profiles yielded the shapes and convective shifts of seven photospheric lines. Results: At the disk center, the bisector profiles of the iron lines feature a pronounced C-shape with maximum convective blueshifts of up to -450 m s-1 in the spectral line wings. Toward the solar limb, the bisectors change into a "\\"-shape with a saturation in the line core at a redshift of +100 m s-1. The center-to-limb variation of the line core velocities shows a slight increase in blueshift when departing the disk center for larger heliocentric angles. This increase in blueshift is more pronounced for the magnetically less active meridian than for the equator. Toward the solar limb, the blueshift decreases and can turn into a redshift. In general, weaker lines exhibit stronger blueshifts. Conclusions: Best spectroscopic measurements enabled the accurate determination of absolute convective shifts in the solar photosphere. We convolved the results to lower spectral

  19. Cross-calibration of interferometric SAR data

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2003-01-01

    Generation of digital elevation models from interferometric synthetic aperture radar (SAR) data is a well established technique. Achieving a high geometric fidelity calls for a calibration accounting for inaccurate navigation data and system parameters as well as system imperfections. Fully......, but not necessarily from map to map. It is based on natural distributed targets for which no a priori knowledge is needed. In particular, no DEM is required as in calibration techniques based on dedicated calibration scenes. To achieve absolute calibration, i.e. elimination of a constant elevation offset, a single...... ground control point is often needed. The paper presents the principles and mathematics of the cross-calibration technique and illustrates its successful application to EMISAR data....

  20. The ATLAS Electromagnetic Calorimeter Calibration Workshop

    CERN Multimedia

    Hong Ma; Isabelle Wingerter

    The ATLAS Electromagnetic Calorimeter Calibration Workshop took place at LAPP-Annecy from the 1st to the 3rd of October; 45 people attended the workshop. A detailed program was setup before the workshop. The agenda was organised around very focused presentations where questions were raised to allow arguments to be exchanged and answers to be proposed. The main topics were: Electronics calibration Handling of problematic channels Cluster level corrections for electrons and photons Absolute energy scale Streams for calibration samples Calibration constants processing Learning from commissioning Forty-five people attended the workshop. The workshop was on the whole lively and fruitful. Based on years of experience with test beam analysis and Monte Carlo simulation, and the recent operation of the detector in the commissioning, the methods to calibrate the electromagnetic calorimeter are well known. Some of the procedures are being exercised in the commisssioning, which have demonstrated the c...

  1. Another look at volume self-calibration: calibration and self-calibration within a pinhole model of Scheimpflug cameras

    International Nuclear Information System (INIS)

    Cornic, Philippe; Le Besnerais, Guy; Champagnat, Frédéric; Illoul, Cédric; Cheminet, Adam; Le Sant, Yves; Leclaire, Benjamin

    2016-01-01

    We address calibration and self-calibration of tomographic PIV experiments within a pinhole model of cameras. A complete and explicit pinhole model of a camera equipped with a 2-tilt angles Scheimpflug adapter is presented. It is then used in a calibration procedure based on a freely moving calibration plate. While the resulting calibrations are accurate enough for Tomo-PIV, we confirm, through a simple experiment, that they are not stable in time, and illustrate how the pinhole framework can be used to provide a quantitative evaluation of geometrical drifts in the setup. We propose an original self-calibration method based on global optimization of the extrinsic parameters of the pinhole model. These methods are successfully applied to the tomographic PIV of an air jet experiment. An unexpected by-product of our work is to show that volume self-calibration induces a change in the world frame coordinates. Provided the calibration drift is small, as generally observed in PIV, the bias on the estimated velocity field is negligible but the absolute location cannot be accurately recovered using standard calibration data. (paper)

  2. Spitzer/JWST Cross Calibration: IRAC Observations of Potential Calibrators for JWST

    Science.gov (United States)

    Carey, Sean J.; Gordon, Karl D.; Lowrance, Patrick; Ingalls, James G.; Glaccum, William J.; Grillmair, Carl J.; E Krick, Jessica; Laine, Seppo J.; Fazio, Giovanni G.; Hora, Joseph L.; Bohlin, Ralph

    2017-06-01

    We present observations at 3.6 and 4.5 microns using IRAC on the Spitzer Space Telescope of a set of main sequence A stars and white dwarfs that are potential calibrators across the JWST instrument suite. The stars range from brightnesses of 4.4 to 15 mag in K band. The calibration observations use a similar redundancy to the observing strategy for the IRAC primary calibrators (Reach et al. 2005) and the photometry is obtained using identical methods and instrumental photometric corrections as those applied to the IRAC primary calibrators (Carey et al. 2009). The resulting photometry is then compared to the predictions based on spectra from the CALSPEC Calibration Database (http://www.stsci.edu/hst/observatory/crds/calspec.html) and the IRAC bandpasses. These observations are part of an ongoing collaboration between IPAC and STScI investigating absolute calibration in the infrared.

  3. TL dosimeters for gamma and thermal neutrons used at ENEA. Accuracy and calibration standards; Dosimetri a TL per neutroni termici e gamma impiegati in ENEA: metodo, calibrazione e qualificazione

    Energy Technology Data Exchange (ETDEWEB)

    Fantuzzi, E.; Gualdrini, G.F.; Monteventi, F.; Morelli, B.; Uleri, G. [ENEA, Centro Ricerche Ezio Clementel, Bologna (Italy). Dipt. Ambiente

    1998-07-01

    This work summaries the experimental results achieved on the characterisation of dosimetric systems used at ENEA (National Agency for New Technology, Energy and the Environment) laboratory in Bologna (Italy) and describes the calibration method either for a two-element dosemeter Harshaw and for a two-element dosemeter assembled at ENEA with higher sensitivity LiF detectors. Both calculation algorithm and calibration procedure have been defined and analyzed in terms of the dosimetric reference quantities. In addition, parameters responsible and crucial for the dosimetric reference quantities. In addition, parameters responsible and crucial for the dosimetric results are pointed out. Finally, intercomparisons between experimental data and numerical data (Monte Carlo code) are shown. [Italian] Vengono esposti i metodi utilizzati per la calibrazione di un dosimetro Harshaw e di uno con maggiore sensibilita' prodotto dal centro ENEA di Bologna con LiF. Sono stati definiti sia l'algoritmo di calcolo sia la procedura di calibrazione ed analizzate le problematiche legate alle grandezze di riferimento. Sono state inoltre individuate le specifiche variabili che possono incidere sul dato dosimetrico ed infine esposti i risultati di interconfronti sperimentali e di calcolo con tecnica Monte Carlo.

  4. Performance standard for dose Calibrator

    CERN Document Server

    Darmawati, S

    2002-01-01

    Dose calibrator is an instrument used in hospitals to determine the activity of radionuclide for nuclear medicine purposes. International Electrotechnical Commission (IEC) has published IEC 1303:1994 standard that can be used as guidance to test the performance of the instrument. This paper briefly describes content of the document,as well as explains the assessment that had been carried out to test the instrument accuracy in Indonesia through intercomparison measurement.Its is suggested that hospitals acquire a medical physicist to perform the test for its dose calibrator. The need for performance standard in the form of Indonesia Standard is also touched.

  5. Relationship between LIBS Ablation and Pit Volume for Geologic Samples: Applications for in situ Absolute Geochronology

    Science.gov (United States)

    Devismes, D.; Cohen, Barbara A.

    2014-01-01

    In planetary sciences, in situ absolute geochronology is a scientific and engineering challenge. Currently, the age of the Martian surface can only be determined by crater density counting. However this method has significant uncertainties and needs to be calibrated with absolute ages. We are developing an instrument to acquire in situ absolute geochronology based on the K-Ar method. The protocol is based on the laser ablation of a rock by hundreds of laser pulses. Laser Induced Breakdown Spectroscopy (LIBS) gives the potassium content of the ablated material and a mass spectrometer (quadrupole or ion trap) measures the quantity of 40Ar released. In order to accurately measure the quantity of released 40Ar in cases where Ar is an atmospheric constituent (e.g., Mars), the sample is first put into a chamber under high vacuum. The 40Arquantity, the concentration of K and the estimation of the ablated mass are the parameters needed to give the age of the rocks. The main uncertainties with this method are directly linked to the measures of the mass (typically some µg) and of the concentration of K by LIBS (up to 10%). Because the ablated mass is small compared to the mass of the sample, and because material is redeposited onto the sample after ablation, it is not possible to directly measure the ablated mass. Our current protocol measures the ablated volume and estimates the sample density to calculate ablated mass. The precision and accuracy of this method may be improved by using knowledge of the sample's geologic properties to predict its response to laser ablation, i.e., understanding whether natural samples have a predictable relationship between laser energy deposited and resultant ablation volume. In contrast to most previous studies of laser ablation, theoretical equations are not highly applicable. The reasons are numerous, but the most important are: a) geologic rocks are complex, polymineralic materials; b) the conditions of ablation are unusual (for example

  6. Self Calibrating Interferometric Sensor

    DEFF Research Database (Denmark)

    Sørensen, Henrik Schiøtt

    with theoretical models for describing the optical phenomena utilized in this technique. A model based on ray–tracing has been developed and shown to be a valuable tool for describing certain features in the fringe pattern. The MIBD measurement technique has been expanded to do absolute determination...... to Maxwell’s equations has with high accuracy described the optical effects when binding events occurs on the inside of a capillary. It is of paramount importance to find a practical stop criteria for the else infinite summation used to find the scattering constants, which is the basis for the model...... microflow chips. The MIBD technology has been transferred to a chip based platform with a close–to–capillary like geometry. These assembled chips has in the MIBD setup shown detection limits of Δn = 4 · 10−6. The fabrication has been done by isotropic etching in silicon through a silicon nitride sacrificial...

  7. Calibration of a modified temperature-light intensity logger for quantifying water electrical conductivity

    Science.gov (United States)

    Gillman, M. A.; Lamoureux, S. F.; Lafrenière, M. J.

    2017-09-01

    The Stream Temperature, Intermittency, and Conductivity (STIC) electrical conductivity (EC) logger as presented by Chapin et al. (2014) serves as an inexpensive (˜50 USD) means to assess relative EC in freshwater environments. This communication demonstrates the calibration of the STIC logger for quantifying EC, and provides examples from a month long field deployment in the High Arctic. Calibration models followed multiple nonlinear regression and produced calibration curves with high coefficient of determination values (R2 = 0.995 - 0.998; n = 5). Percent error of mean predicted specific conductance at 25°C (SpC) to known SpC ranged in magnitude from -0.6% to 13% (mean = -1.4%), and mean absolute percent error (MAPE) ranged from 2.1% to 13% (mean = 5.3%). Across all tested loggers we found good accuracy and precision, with both error metrics increasing with increasing SpC values. During 10, month-long field deployments, there were no logger failures and full data recovery was achieved. Point SpC measurements at the location of STIC loggers recorded via a more expensive commercial electrical conductivity logger followed similar trends to STIC SpC records, with 1:1.05 and 1:1.08 relationships between the STIC and commercial logger SpC values. These results demonstrate that STIC loggers calibrated to quantify EC are an economical means to increase the spatiotemporal resolution of water quality investigations.

  8. Design, test, and calibration of an electrostatic beam position monitor

    Directory of Open Access Journals (Sweden)

    Maurice Cohen-Solal

    2010-03-01

    Full Text Available The low beta of proton or ion beams favors an electrostatic pickup to measure the transverse beam centroid position. Often papers on beam position monitors (BPM are focused on a particular aspect of the problem; however, it is important to consider all various issues of a position measurement system. Based on our experience at the IPHI (high intensity injector proton facility at CEA-Saclay, this paper will address all aspects to design, test, and calibrate a BPM for proton linear accelerators, while emphasizing the determination of the absolute beam position. We present details of the readout electronics, and describe the calibration of the BPM using a test station. For calculation and simulation of the electrical signals we developed a Mathematica script. The error analysis presented, on the basis of six BPMs installed in the high energy section of IPHI, demonstrates the expected accuracy of the position measurement. These studies also identify the parameters that could improve the performance of the beam position control. The experience from these developments is currently being used for the BPM design and test stand dedicated to the Spiral2 accelerator at Ganil-Caen which will deliver heavy ion beams.

  9. Absolute dating of the Aegean Late Bronze Age

    International Nuclear Information System (INIS)

    Warren, P.M.

    1987-01-01

    A recent argument for raising the absolute date of the beginning of the Aegean Late Bronze (LB) Age to about 1700 B.C. is critically examined. It is argued here that: (1) the alabaster lid from Knossos did have the stratigraphical context assigned to it by Evans, in all probability Middle Minoan IIIA, c. 1650 B.C.; (2) the attempt to date the alabastron found in an early Eighteenth Dynasty context at Aniba to Late Minoan IIIA:1 is open to objections; (3) radiocarbon dates from Aegean LB I contexts are too wide in their calibrated ranges and too inconsistent both within and between site sets to offer any reliable grounds at present for raising Aegean LB I absolute chronology to 1700 B.C. Other evidence, however, suggests this period began about 1600 B.C., i.e. some fifty years earlier than the conventional date of 1550 B.C. (author)

  10. Absolute MR thermometry using nanocarriers.

    Science.gov (United States)

    Deckers, Roel; Sprinkhuizen, Sara M; Crielaard, Bart J; Ippel, Johannes H; Boelens, Rolf; Bakker, Chris J G; Storm, Gert; Lammers, Twan; Bartels, Lambertus W

    2014-01-01

    Accurate time-resolved temperature mapping is crucial for the safe use of hyperthermia-mediated drug delivery. We here propose a magnetic resonance imaging temperature mapping method in which drug delivery systems serve not only to improve tumor targeting, but also as an accurate and absolute nano-thermometer. This method is based on the temperature-dependent chemical shift difference between water protons and the protons in different groups of drug delivery systems. We show that the chemical shift of the protons in the ethylene oxide group in polyethylene glycol (PEG) is temperature-independent, whereas the proton resonance of water decreases with increasing temperature. The frequency difference between both resonances is linear and does not depend on pH and physiological salt conditions. In addition, we show that the proton resonance of the methyl group in N-(2-hydroxypropyl)-methacrylamide (HPMA) is temperature-independent. Therefore, PEGylated liposomes, polymeric mPEG-b-pHPMAm-Lac2 micelles and HPMA copolymers can provide a temperature-independent reference frequency for absolute magnetic resonance (MR) thermometry. Subsequently, we show that multigradient echo MR imaging with PEGylated liposomes in situ allows accurate, time-resolved temperature mapping. In conclusion, nanocarrier materials may serve as highly versatile tools for tumor-targeted drug delivery, acting not only as hyperthermia-responsive drug delivery systems, but also as accurate and precise nano-thermometers. Copyright © 2014 John Wiley & Sons, Ltd.

  11. First absolute measurements of fast-ion losses in the ASDEX Upgrade tokamak

    Science.gov (United States)

    Rodriguez-Ramos, M.; Garcia-Munoz, M.; Jimenez-Ramos, M. C.; Garcia Lopez, J.; Galdon-Quiroga, J.; Sanchis-Sanchez, L.; Ayllon-Guerola, J.; Faitsch, M.; Gonzalez-Martin, J.; Hermann, A.; de Marne, P.; Rivero-Rodriguez, J. F.; Sieglin, B.; Snicker, A.; the ASDEX Upgrade Team

    2017-10-01

    A new diagnostic technique that allows to obtain absolute fluxes of fast-ion losses measured with absolutely calibrated scintillator based fast-ion loss detectors (FILD) is presented here. First absolute fluxes of fast-ion losses have been obtained in the ASDEX Upgrade tokamak. An instrument function that includes the scintillator efficiency, collimator geometry, optical transmission and camera efficiency has been constructed. The scintillator response to deuterium ions in the relevant energy range of fast-ions has been characterized using a tandem accelerator. Absolute flux of neutral beam injection (NBI) prompt losses has been obtained in magnetohydrodynamic quiescent plasmas. The temporal evolution of the heat load measured with FILD follows that measured at the FILD entrance obtained with an Infra-Red camera looking at the FILD detector head. ASCOT simulations are in good agreement with the absolute heat load of NBI prompt losses measured with FILD.

  12. Performance evaluations of continuous glucose monitoring systems: precision absolute relative deviation is part of the assessment.

    Science.gov (United States)

    Obermaier, Karin; Schmelzeisen-Redeker, Günther; Schoemaker, Michael; Klötzer, Hans-Martin; Kirchsteiger, Harald; Eikmeier, Heino; del Re, Luigi

    2013-07-01

    Even though a Clinical and Laboratory Standards Institute proposal exists on the design of studies and performance criteria for continuous glucose monitoring (CGM) systems, it has not yet led to a consistent evaluation of different systems, as no consensus has been reached on the reference method to evaluate them or on acceptance levels. As a consequence, performance assessment of CGM systems tends to be inconclusive, and a comparison of the outcome of different studies is difficult. Published information and available data (as presented in this issue of Journal of Diabetes Science and Technology by Freckmann and coauthors) are used to assess the suitability of several frequently used methods [International Organization for Standardization, continuous glucose error grid analysis, mean absolute relative deviation (MARD), precision absolute relative deviation (PARD)] when assessing performance of CGM systems in terms of accuracy and precision. The combined use of MARD and PARD seems to allow for better characterization of sensor performance. The use of different quantities for calibration and evaluation, e.g., capillary blood using a blood glucose (BG) meter versus venous blood using a laboratory measurement, introduces an additional error source. Using BG values measured in more or less large intervals as the only reference leads to a significant loss of information in comparison with the continuous sensor signal and possibly to an erroneous estimation of sensor performance during swings. Both can be improved using data from two identical CGM sensors worn by the same patient in parallel. Evaluation of CGM performance studies should follow an identical study design, including sufficient swings in glycemia. At least a part of the study participants should wear two identical CGM sensors in parallel. All data available should be used for evaluation, both by MARD and PARD, a good PARD value being a precondition to trust a good MARD value. Results should be analyzed and

  13. (1) H-NMR quantification of major saccharides in açaí raw materials: a comparison of the internal standard methodology with the absolute intensity qNMR method.

    Science.gov (United States)

    Sterling, Cole; Crouch, Ronald; Russell, David J; Calderón, Angela I

    2013-01-01

    While the use of internal standard methodology for qNMR is a proven and reliable form of quantification, simplified alternative approaches are needed. Agilent's absolute intensity qNMR utility software is a valuable alternative that has not yet been subjected to validation in the peer-reviewed literature. To provide validation of Agilent's absolute intensity qNMR method with a specific application to natural product quantification by measuring saccharide content in açaí materials. In order to validate the method, calibration test samples of ibuprofen were prepared in DMSO-d6 at nine different concentrations and measured with (1) H-NMR. A minimum of 40 spectra were collected for each sample, and the absolute intensity utility was used for quantification. The same methodology was then applied to the açaí materials, creating triplicates for each of the materials and using 3-(trimethylsilyl)-1-propanesulphonic acid sodium salt in water-d2 as both the solvent and internal standard. (1) H-NMR spectra were collected, and the amounts of glucose, sucrose and fructose were determined using both the internal standard approach and the absolute intensity qNMR method. Applying the absolute intensity utility to the ibuprofen samples demonstrated a linear response (R(2)  = 0.99943). For the açaí investigations, results obtained from the absolute intensity method were comparable to those obtained from the internal standard approach, with percentage differences ranging from 0.5-6.2%. This study demonstrates the accuracy, precision and reliability of Agilent's absolute intensity qNMR method. In addition, practical information is provided for assessing the saccharide contents of açaí materials. Copyright © 2013 John Wiley & Sons, Ltd.

  14. Calibration and intercomparison methods of dose calibrators used in nuclear medicine facilities

    International Nuclear Information System (INIS)

    Costa, Alessandro Martins da

    1999-01-01

    Dose calibrators are used in most of the nuclear medicine facilities to determine the amount of radioactivity administered to a patient in a particular investigation or therapeutic procedure. It is therefore of vital importance that the equipment used presents good performance and is regular;y calibrated at a authorized laboratory. This occurs of adequate quality assurance procedures are carried out. Such quality control tests should be performed daily, other biannually or yearly, testing, for example, its accuracy and precision, the reproducibility and response linearity. In this work a commercial dose calibrator was calibrated with solution of radionuclides used in nuclear medicine. Simple instrument tests, such as response linearity and the response variation of the source volume increase at a constant source activity concentration, were performed. This instrument can now be used as a working standard for calibration of other dose calibrators/ An intercomparison procedure was proposed as a method of quality control of dose calibrators used in nuclear medicine facilities. (author)

  15. "Absolute" sterility and "absolute" freedom from particle contamination.

    Science.gov (United States)

    Knapp, J Z

    1998-01-01

    Until the recent past, sterility of an injectable product was only discussed in absolute terms. Any description of sterility other than as an absolute could simply not be envisioned. While dealing in absolute yes/no statements is philosophically satisfying, these yes/no statements can't accommodate all real world scientific problems. Among these problems is the sterility problems faced in the mass production of injectable compounds. Many descriptions of procedures employed to achieve sterility in parenteral production batches were reported in the literature. The theoretical framework that could unite the widespread observations and practices into practical methodology was missing until recently. Production line control of the sterility of injectable products was essentially based on gut evaluations. The present achievement of rational, production line control of product sterility is based on the recognition that product sterility could not be simply regarded as a sharply edged yes/no affair. The present rational control is based on the fact that the sterility of a product is determined by the degree of contamination in the product prior to sterilization and to the parameters of the sterilization process. The end result of the sterilization process is now described as a probabalistic reduction of the initial contamination. The essential laboratory measurements on which this conclusion was based is due to Pflug (1-3). He assembled a theoretical framework, based on experimental data, that characterizes the sterility achieved in an injectable product with a single number. The end result of the sterilization process is now described as a probabalistic reduction of the initial contamination. As in many disciplines, the ability to achieve an objective evaluation of this important attribute provided the basis for scientific analysis, improved control and thus improved production and reduced cost. An equivalent framework is essential for the communication and

  16. Tolerance on sphere radius for the calibration of the transfer function of coherence scanning interferometry

    Science.gov (United States)

    Su, Rong; Coupland, Jeremy M.; Wang, Yuhang; Leach, Richard K.

    2017-06-01

    Although coherence scanning interferometry (CSI) commonly achieves a sub-nanometre noise level in surface topography measurement, the absolute accuracy is difficult to determine when measuring a surface that contains varying local slope angles and curvatures. Recent research has shown that it is possible to use a single sphere with a radius much greater than the source wavelength to calibrate the three-dimensional transfer function of a CSI system. A major requirement is the accurate knowledge of the sphere radius, but the three-dimensional measurement of a sphere with nanometre level uncertainty is a highly challenging metrology problem, and is not currently feasible. Perfect spheres do not exist and every measurement has uncertainty. Without having a quantitative understanding of the tolerance of the sphere radius, the calibration method cannot be used confidently for calibration of the transfer function of a CSI system that may be used in research laboratories or industry. In this paper, the effects of the tolerance of the radius of the calibration sphere on surface topography measurements are quantitatively analysed through a computational approach. CSI measurements of spherical, sinusoidal and rough surfaces are investigated in the presence of various degrees of radius error. A lookup table that relates the surface height error as a function of the radius error and surface slope angle is provided. The users may estimate the required tolerances of the sphere radius for their specific surface measurements if this calibration approach is used. The output of this paper provides a feasibility analysis for this calibration method for further development and applications.

  17. Satellite Instrument Calibration for Measuring Global Climate Change. Report of a Workshop at the University of Maryland Inn and Conference Center, College Park, MD. , November 12-14, 2002

    Science.gov (United States)

    Ohring, G.; Wielicki, B.; Spencer, R.; Emery, B.; Datla, R.

    2004-01-01

    Measuring the small changes associated with long-term global climate change from space is a daunting task. To address these problems and recommend directions for improvements in satellite instrument calibration some 75 scientists, including researchers who develop and analyze long-term data sets from satellites, experts in the field of satellite instrument calibration, and physicists working on state of the art calibration sources and standards met November 12 - 14, 2002 and discussed the issues. The workshop defined the absolute accuracies and long-term stabilities of global climate data sets that are needed to detect expected trends, translated these data set accuracies and stabilities to required satellite instrument accuracies and stabilities, and evaluated the ability of current observing systems to meet these requirements. The workshop's recommendations include a set of basic axioms or overarching principles that must guide high quality climate observations in general, and a roadmap for improving satellite instrument characterization, calibration, inter-calibration, and associated activities to meet the challenge of measuring global climate change. It is also recommended that a follow-up workshop be conducted to discuss implementation of the roadmap developed at this workshop.

  18. 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.

  19. 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

  20. Traceable X,Y self-calibration at single nm level of an optical microscope used for coherence scanning interferometry

    Science.gov (United States)

    Ekberg, Peter; Mattsson, Lars

    2018-03-01

    Coherence scanning interferometry used in optical profilers are typically good for Z-calibration at nm-levels, but the X,Y accuracy is often left without further notice than typical resolution limits of the optics, i.e. of the order of ~1 µm. For the calibration of metrology tools we rely on traceable artefacts, e.g. gauge blocks for traditional coordinate measurement machines, and lithographically mask made artefacts for microscope calibrations. In situations where the repeatability and accuracy of the measurement tool is much better than the uncertainty of the traceable artefact, we are bound to specify the uncertainty based on the calibration artefact rather than on the measurement tool. This is a big drawback as the specified uncertainty of a calibrated measurement may shrink the available manufacturing tolerance. To improve the uncertainty in X,Y we can use self-calibration. Then, we do not need to know anything more than that the artefact contains a pattern with some nominal grid. This also gives the opportunity to manufacture the artefact in-house, rather than buying a calibrated and expensive artefact. The self-calibration approach we present here is based on an iteration algorithm, rather than the traditional mathematical inversion, and it leads to much more relaxed constrains on the input measurements. In this paper we show how the X,Y errors, primarily optical distortions, within the field of view (FOV) of an optical coherence scanning interferometry microscope, can be reduced with a large factor. By self-calibration we achieve an X,Y consistency in the 175  ×  175 µm2 FOV of ~2.3 nm (1σ) using the 50×  objective. Besides the calibrated coordinate X,Y system of the microscope we also receive, as a bonus, the absolute positions of the pattern in the artefact with a combined uncertainty of 6 nm (1σ) by relying on a traceable 1D linear measurement of a twin artefact at NIST.

  1. Signal Processing and Calibration of Continuous-Wave Focused CO2 Doppler Lidars for Atmospheric Backscatter Measurement

    Science.gov (United States)

    Rothermel, Jeffry; Chambers, Diana M.; Jarzembski, Maurice A.; Srivastava, Vandana; Bowdle, David A.; Jones, William D.

    1996-01-01

    Two continuous-wave(CW)focused C02 Doppler lidars (9.1 and 10.6 micrometers) were developed for airborne in situ aerosol backscatter measurements. The complex path of reliably calibrating these systems, with different signal processors, for accurate derivation of atmospheric backscatter coefficients is documented. Lidar calibration for absolute backscatter measurement for both lidars is based on range response over the lidar sample volume, not solely at focus. Both lidars were calibrated with a new technique using well-characterized aerosols as radiometric standard targets and related to conventional hard-target calibration. A digital signal processor (DSP), a surface acoustic and spectrum analyzer and manually tuned spectrum analyzer signal analyzers were used. The DSP signals were analyzed with an innovative method of correcting for systematic noise fluctuation; the noise statistics exhibit the chi-square distribution predicted by theory. System parametric studies and detailed calibration improved the accuracy of conversion from the measured signal-to-noise ratio to absolute backscatter. The minimum backscatter sensitivity is approximately 3 x 10(exp -12)/m/sr at 9.1 micrometers and approximately 9 x 10(exp -12)/m/sr at 10.6 micrometers. Sample measurements are shown for a flight over the remote Pacific Ocean in 1990 as part of the NASA Global Backscatter Experiment (GLOBE) survey missions, the first time to our knowledge that 9.1-10.6 micrometer lidar intercomparisons were made. Measurements at 9.1 micrometers, a potential wavelength for space-based lidar remote-sensing applications, are to our knowledge the first based on the rare isotope C-12 O(2)-18 gas.

  2. Gauge calibration system based on piston manometer

    Science.gov (United States)

    Warshawsky, I.

    1981-01-01

    An unbaked calibration system is described that permits absolute calibration with a piston manometer in the range 0.0002 to 6 Pa, with a probable error of 5 microPa + 0.8%, or in the range 0.00008 to 0.02 Pa, with a probable error of 2 microPa + 1%. Procedures and techniques that permit this performance are detailed. For hot-cathode ion gauges, the magnitudes of systematic corrections for envelope temperature and grid current are also indicated.

  3. A rediscussion of the atmospheric extinction and the absolute spectral-energy distribution of Vega

    International Nuclear Information System (INIS)

    Hayes, D.S.; Latham, D.W.

    1975-01-01

    For both the Lick and the Palomar calibrations of the spectral-energy distribution of Vega, the atmospheric extinction was treated incorrectly. We present a model for extinction in the Earth's atmosphere and use this model to calculate corrections to the Lick and Palomar calibrations. We also describe a method that can be used to fabricate mean extinction coefficients for any mountain observatory. We combine selected portions of the corrected Lick and corrected Palomar calibrations with the new Mount Hopkins calibration to generate an absolute spectral-energy distibution of Vega over the wavelength range 3300--10,800 A. Until better measurements become available, we recommend the use of this calibration for all practical applications

  4. 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.

  5. The Importance of Calibration in Clinical Psychology.

    Science.gov (United States)

    Lindhiem, Oliver; Petersen, Isaac T; Mentch, Lucas K; Youngstrom, Eric A

    2018-02-01

    Accuracy has several elements, not all of which have received equal attention in the field of clinical psychology. Calibration, the degree to which a probabilistic estimate of an event reflects the true underlying probability of the event, has largely been neglected in the field of clinical psychology in favor of other components of accuracy such as discrimination (e.g., sensitivity, specificity, area under the receiver operating characteristic curve). Although it is frequently overlooked, calibration is a critical component of accuracy with particular relevance for prognostic models and risk-assessment tools. With advances in personalized medicine and the increasing use of probabilistic (0% to 100%) estimates and predictions in mental health research, the need for careful attention to calibration has become increasingly important.

  6. Absolute GPS Time Event Generation and Capture for Remote Locations

    Science.gov (United States)

    HIRES Collaboration

    The HiRes experiment operates fixed location and portable lasers at remote desert locations to generate calibration events. One physics goal of HiRes is to search for unusual showers. These may appear similar to upward or horizontally pointing laser tracks used for atmospheric calibration. It is therefore necessary to remove all of these calibration events from the HiRes detector data stream in a physics blind manner. A robust and convenient "tagging" method is to generate the calibration events at precisely known times. To facilitate this tagging method we have developed the GPSY (Global Positioning System YAG) module. It uses a GPS receiver, an embedded processor and additional timing logic to generate laser triggers at arbitrary programmed times and frequencies with better than 100nS accuracy. The GPSY module has two trigger outputs (one microsecond resolution) to trigger the laser flash-lamp and Q-switch and one event capture input (25nS resolution). The GPSY module can be programmed either by a front panel menu based interface or by a host computer via an RS232 serial interface. The latter also allows for computer logging of generated and captured event times. Details of the design and the implementation of these devices will be presented. 1 Motivation Air Showers represent a small fraction, much less than a percent, of the total High Resolution Fly's Eye data sample. The bulk of the sample is calibration data. Most of this calibration data is generated by two types of systems that use lasers. One type sends light directly to the detectors via optical fibers to monitor detector gains (Girard 2001). The other sends a beam of light into the sky and the scattered light that reaches the detectors is used to monitor atmospheric effects (Wiencke 1998). It is important that these calibration events be cleanly separated from the rest of the sample both to provide a complete set of monitoring information, and more

  7. Absolute activity determination of I-125 in the thyroid

    International Nuclear Information System (INIS)

    Pelled, O.; German, U.; Kol, R.; Levinson, S.; Laichter, Y.

    1997-01-01

    I-125 has been widely used in nuclear medicine and as a tracer in different experiments. The dose equivalent to the thyroid Tom internal contamination of 1-125, can be estimated by in-vivo monitoring of the thyroid or through bioassay of urine . The in-vivo monitoring of the thyroid can be carried out by counting the photon emission from the decay of the 1-125 , by a Nal(Tl) detector calibrated with a thyroid phantom. This direct method is sensitive , but due to the low photon energy (27keV to 35keV), the counting efficiency depends strongly on the variations of the thyroid mass , thyroid depth below the surface , thyroid shape and detector position . It is estimated that the uncertainty of the activity determination can reach several hundred percents . A mewed for absolute determination of the activity of a '251 source based on the counting rate values of file 27 keV photons and the 54 keV coincidence photo peak, which diminishes the geometry dependence of the counting efficiency , was applied to determine the uptake of 125-I in human thyroid In this work we checked also the application of the absolute determination method wife high sensitivity phoswich detectors. We compare the results of calculations of interval exposure to 125-I for a real case, evaluated by the absolute determination method and by the direct method. (authors)

  8. Enhancement of diffusers BRDF accuracy

    Science.gov (United States)

    Otter, Gerard; Bazalgette Courrèges-Lacoste, Gregory; van Brug, Hedser; Schaarsberg, Jos Groote; Delwart, Steven; del Bello, Umberto

    2017-11-01

    This paper reports the result of an ESA study conducted at TNO to investigate properties of various diffusers. Diffusers are widely used in space instruments as part of the on-board absolute calibration. Knowledge of the behaviour of the diffuser is therefore most important. From measurements of launched instruments in-orbit it has been discovered that when a diffuser is used in the vacuum of space the BRDF can change with respect to the one in ambient conditions. This is called the air/vacuum effect and has been simulated in this study by measuring the BRDF in a laboratory in ambient as well as vacuum conditions. Another studied effect is related to the design parameters of the optical system and the scattering properties of the diffuser. The effect is called Spectral Features and is a noise like structure superimposed on the diffuser BRDF. Modern space spectrometers, which have high spectral resolution and/or a small field of view (high spatial resolution) are suffering from this effect. The choice of diffuser can be very critical with respect to the required absolute radiometric calibration of an instrument. Even if the Spectral Features are small it can influence the error budget of the retrieval algorithms for the level 2 products. in this presentation diffuser trade-off results are presented and the Spectral Features model applied to the optical configuration of the MERIS instrument is compared to in-flight measurements of MERIS.

  9. UAV CAMERAS: OVERVIEW AND GEOMETRIC CALIBRATION BENCHMARK

    Directory of Open Access Journals (Sweden)

    M. Cramer

    2017-08-01

    Full Text Available Different UAV platforms and sensors are used in mapping already, many of them equipped with (sometimes modified cameras as known from the consumer market. Even though these systems normally fulfil their requested mapping accuracy, the question arises, which system performs best? This asks for a benchmark, to check selected UAV based camera systems in well-defined, reproducible environments. Such benchmark is tried within this work here. Nine different cameras used on UAV platforms, representing typical camera classes, are considered. The focus is laid on the geometry here, which is tightly linked to the process of geometrical calibration of the system. In most applications the calibration is performed in-situ, i.e. calibration parameters are obtained as part of the project data itself. This is often motivated because consumer cameras do not keep constant geometry, thus, cannot be seen as metric cameras. Still, some of the commercial systems are quite stable over time, as it was proven from repeated (terrestrial calibrations runs. Already (pre-calibrated systems may offer advantages, especially when the block geometry of the project does not allow for a stable and sufficient in-situ calibration. Especially for such scenario close to metric UAV cameras may have advantages. Empirical airborne test flights in a calibration field have shown how block geometry influences the estimated calibration parameters and how consistent the parameters from lab calibration can be reproduced.

  10. Uav Cameras: Overview and Geometric Calibration Benchmark

    Science.gov (United States)

    Cramer, M.; Przybilla, H.-J.; Zurhorst, A.

    2017-08-01

    Different UAV platforms and sensors are used in mapping already, many of them equipped with (sometimes) modified cameras as known from the consumer market. Even though these systems normally fulfil their requested mapping accuracy, the question arises, which system performs best? This asks for a benchmark, to check selected UAV based camera systems in well-defined, reproducible environments. Such benchmark is tried within this work here. Nine different cameras used on UAV platforms, representing typical camera classes, are considered. The focus is laid on the geometry here, which is tightly linked to the process of geometrical calibration of the system. In most applications the calibration is performed in-situ, i.e. calibration parameters are obtained as part of the project data itself. This is often motivated because consumer cameras do not keep constant geometry, thus, cannot be seen as metric cameras. Still, some of the commercial systems are quite stable over time, as it was proven from repeated (terrestrial) calibrations runs. Already (pre-)calibrated systems may offer advantages, especially when the block geometry of the project does not allow for a stable and sufficient in-situ calibration. Especially for such scenario close to metric UAV cameras may have advantages. Empirical airborne test flights in a calibration field have shown how block geometry influences the estimated calibration parameters and how consistent the parameters from lab calibration can be reproduced.

  11. Technical preparations for the in-vessel 14 MeV neutron calibration at JET

    Energy Technology Data Exchange (ETDEWEB)

    Batistoni, P., E-mail: paola.batistoni@enea.it [ENEA, Department of Fusion and Nuclear Safety Technology, I-00044, Frascati, Rome (Italy); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); Popovichev, S. [CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); Crowe, R. [Remote Applications in Challenging Environments (RACE), Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); Cufar, A. [Reactor Physics Division, Jožef Stefan Institute, Jamova cesta 39, SI-1000, Ljubljana (Slovenia); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); Ghani, Z. [CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); Keogh, K. [Remote Applications in Challenging Environments (RACE), Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); Peacock, A. [JET Exploitation Unit, Abingdon, Oxon, OX14 3DB (United Kingdom); Price, R. [Remote Applications in Challenging Environments (RACE), Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); Baranov, A.; Korotkov, S.; Lykin, P.; Samoshin, A. [All-Russia Research Institute of Automatics (VNIIA), 22, Sushchevskaya str., 127055, Moscow (Russian Federation)

    2017-04-15

    Highlights: • The JET 14 MeV neutron calibration requires a neutron generator to be deployed inside the vacuum vessel by means of the remote handling system. • A neutron generator of suitable intensity and compliant with physics, remote handling and safety requirements has been identified and procured.The scientific programme of the preparatory phase devoted to fully characterizing the selected 14 MeV neutron generator is discussed. • The aim is to measure the absolute neutron emission rate within (± 5%) and the energy spectrum of emitted neutron as a function of angles. • The physics preparations, source issues, safety and engineering aspects required to calibrate directly the JET neutron detectors are discussed. - Abstract: The power output of fusion devices is measured from their neutron yields which relate directly to the fusion yield. In this paper we describe the devices and methods that have been prepared to perform a new in situ 14 MeV neutron calibration at JET in view of the new DT campaign planned at JET in the next years. The target accuracy of this calibration is ±10% as required for ITER, where a precise neutron yield measurement is important, e.g., for tritium accountancy. In this paper, the constraints and early decisions which defined the main calibration approach are discussed, e.g., the choice of 14 MeV neutron source and the deployment method. The physics preparations, source issues, safety and engineering aspects required to calibrate directly the JET neutron detectors are also discussed. The existing JET remote-handling system will be used to deploy the neutron source inside the JET vessel. For this purpose, compatible tooling and systems necessary to ensure safe and efficient deployment have been developed. The scientific programme of the preparatory phase is devoted to fully characterizing the selected 14 MeV neutron generator to be used as the calibrating source, obtain a better understanding of the limitations of the

  12. Technical preparations for the in-vessel 14 MeV neutron calibration at JET

    International Nuclear Information System (INIS)

    Batistoni, P.; Popovichev, S.; Crowe, R.; Cufar, A.; Ghani, Z.; Keogh, K.; Peacock, A.; Price, R.; Baranov, A.; Korotkov, S.; Lykin, P.; Samoshin, A.

    2017-01-01

    Highlights: • The JET 14 MeV neutron calibration requires a neutron generator to be deployed inside the vacuum vessel by means of the remote handling system. • A neutron generator of suitable intensity and compliant with physics, remote handling and safety requirements has been identified and procured.The scientific programme of the preparatory phase devoted to fully characterizing the selected 14 MeV neutron generator is discussed. • The aim is to measure the absolute neutron emission rate within (± 5%) and the energy spectrum of emitted neutron as a function of angles. • The physics preparations, source issues, safety and engineering aspects required to calibrate directly the JET neutron detectors are discussed. - Abstract: The power output of fusion devices is measured from their neutron yields which relate directly to the fusion yield. In this paper we describe the devices and methods that have been prepared to perform a new in situ 14 MeV neutron calibration at JET in view of the new DT campaign planned at JET in the next years. The target accuracy of this calibration is ±10% as required for ITER, where a precise neutron yield measurement is important, e.g., for tritium accountancy. In this paper, the constraints and early decisions which defined the main calibration approach are discussed, e.g., the choice of 14 MeV neutron source and the deployment method. The physics preparations, source issues, safety and engineering aspects required to calibrate directly the JET neutron detectors are also discussed. The existing JET remote-handling system will be used to deploy the neutron source inside the JET vessel. For this purpose, compatible tooling and systems necessary to ensure safe and efficient deployment have been developed. The scientific programme of the preparatory phase is devoted to fully characterizing the selected 14 MeV neutron generator to be used as the calibrating source, obtain a better understanding of the limitations of the

  13. Results of Absolute Cavity Pyrgeometer and Infrared Integrating Sphere Comparisons

    Energy Technology Data Exchange (ETDEWEB)

    Reda, Ibrahim M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sengupta, Manajit [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dooraghi, Michael R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Grobner, Julian [Physikalisch-Meteorologisches Observatorium Davos (PMOD); Thomann, Christian [Physikalisch-Meteorologisches Observatorium Davos (PMOD); Long, Chuck [National Oceanic and Atmospheric Administration; McComiskey, Allison [National Oceanic and Atmospheric Administration; Hall, Emiel [National Oceanic and Atmospheric Administration; Wacker, Stefan [Deutscher Wetterdienst

    2018-03-05

    Accurate and traceable atmospheric longwave irradiance measurements are required for understanding radiative impacts on the Earth's energy budget. The standard to which pyrgeometers are traceable is the interim World Infrared Standard Group (WISG), maintained in the Physikalisch-Meteorologisches Observatorium Davos (PMOD). The WISG consists of four pyrgeometers that were calibrated using Rolf Philipona's Absolute Sky-scanning Radiometer [1]. The Atmospheric Radiation Measurement (ARM) facility has recently adopted the WISG to maintain the traceability of the calibrations of all Eppley precision infrared radiometer (PIR) pyrgeometers. Subsequently, Julian Grobner [2] developed the infrared interferometer spectrometer and radiometer (IRIS) radiometer, and Ibrahim Reda [3] developed the absolute cavity pyrgeometer (ACP). The ACP and IRIS were developed to establish a world reference for calibrating pyrgeometers with traceability to the International System of Units (SI). The two radiometers are unwindowed with negligible spectral dependence, and they are traceable to SI units through the temperature scale (ITS-90). The two instruments were compared directly to the WISG three times at PMOD and twice at the Southern Great Plains (SGP) facility to WISG-traceable pyrgeometers. The ACP and IRIS agreed within +/- 1 W/m2 to +/- 3 W/m2 in all comparisons, whereas the WISG references exhibit a 2-5 Wm2 low bias compared to the ACP/IRIS average, depending on the water vapor column, as noted in Grobner et al. [4]. Consequently, a case for changing the current WISG has been made by Grobner and Reda. However, during the five comparisons the column water vapor exceeded 8 mm. Therefore, it is recommended that more ACP and IRIS comparisons should be held under different environmental conditions and water vapor column content to better establish the traceability of these instruments to SI with established uncertainty.

  14. Calibration of film radiochromic EBT2 for sources of I-125 encapsulated; Calibracion de pelicula radiocromica EBT2 para fuentes de I-125 encapsulado

    Energy Technology Data Exchange (ETDEWEB)

    Huerga Cabrerizo, C.; Luquero Llopis, N.; Torre Hernandez, I. de la; Ferrer Garcia, C.; Corredoira silva, E.; Serrada Hierro, A.

    2013-07-01

    This paper determines the calibration curve in absolute dose for sources of I-125 encapsulated to estimate its uncertainty. In order to assess energy dependence is compared with the obtained for an accelerator of 6MV calibration curve. (Author)

  15. Calibration Techniques for Accurate Measurements by Underwater Camera Systems.

    Science.gov (United States)

    Shortis, Mark

    2015-12-07

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems.

  16. Calibration Techniques for Accurate Measurements by Underwater Camera Systems

    Directory of Open Access Journals (Sweden)

    Mark Shortis

    2015-12-01

    Full Text Available Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems.

  17. A water flow calorimeter calibration system

    International Nuclear Information System (INIS)

    Ullrich, F.T.

    1983-01-01

    Neutral beam systems are instrumented by several water flow calorimeter systems, and some means is needed to verify the accuracy of such systems and diagnose their failures. This report describes a calibration system for these calorimeters. The calibrator consists of two 24 kilowatt circulation water heaters, with associated controls and instrumentation. The unit can supply power from 0 to 48 kW in five coarse steps and one fine range. Energy is controlled by varying the power and the time of operation of the heaters. The power is measured by means of precision power transducers, and the energy is measured by integrating the power with respect to time. The accuracy of the energy measurement is better than 0.5% when the power supplied is near full scale, and the energy resolution is better than 1 kilojoule. The maximum energy delivered is approximately 50 megajoules. The calorimetry loop to be calibrated is opened, and the calibrator is put in series with the calorimeter heat source. The calorimeter is then operated in its normal fashion, with the calibrator used as the heat source. The calibrator can also be used in a stand alone mode to calibrate calorimeter sensors removed from systems

  18. An Experimental Benchmark for Improved Simulation of Absolute Soft X-Ray Emission from Polystyrene Targets Irradiated With the Nike Laser

    National Research Council Canada - National Science Library

    Weaver, J. L; Busquet, M; Colombant, D. G; Mostovych, A. N; Feldman, U; Klapisch, M; Seely, J. F; Brown, C; Holland, G

    2005-01-01

    Absolutely calibrated, time-resolved spectral intensity measurements of soft x-ray emission from laser-irradiated polystyrene targets are compared to radiation-hydrodynamic simulations that include...

  19. Memory for musical tempo: Additional evidence that auditory memory is absolute

    OpenAIRE

    Levitin, Daniel J.; Cook, Perry R.

    1996-01-01

    We report evidence that long term memory retains absolute (accurate) features of perceptual events. Specifically, we show that memory for music seems to preserve the absolute tempo of the musical performance. In Experiment 1, 46 subjects sang popular songs from memory, and their tempos were compared to recorded versions of the songs. Seventy-two of the subjects came within 8% of the actual tempo on two consecutive trials (using different songs), demonstrating accuracy near the perceptual thre...

  20. Calibration Lessons Learned from Hyperion Experience

    Science.gov (United States)

    Casement, S.; Ho, K.; Sandor-Leahy, S.; Biggar, S.; Czapla-Myers, J.; McCorkel, J.; Thome, K.

    2009-12-01

    The use of hyperspectral imagers to provide climate-quality data sets, such as those expected from the solar reflective sensor on the Climate Absolute Radiance and Refractivity Observatory (CLARREO), requires stringent radiometric calibration requirements. These stringent requirements have been nearly met with broadband radiometers such as CERES, but high resolution spectrometers pose additional challenges. A review of the calibration processes for past space-based HSIs provide guidance on the calibration processes that will be needed for future sensors. In November 2000, the Earth Observer-1 (EO-1) platform was launched onboard a Boeing Delta II launch vehicle. The primary purpose of the EO-1 mission was to provide a technological testbed for spaceborne components. The platform has three sensors onboard, of which, the hyperspectral imager (HSI) Hyperion, is discussed here. The Hyperion sensor at the time had no comparable sensor in earth orbit, being the first grating-based, hyperspectral, civilian sensor in earth orbit. Ground and on-orbit calibration procedures including all cross-calibration activities have achieved an estimated instrument absolute radiometric error of 2.9% in the Visible channel (0.4 - 1.0 microns) and 3.4% in the shortwave infrared (SWIR, 0.9 - 2.5 microns) channel (EO-1/Hyperion Early Orbit Checkout Report Part II On-Orbit Performance Verification and Calibration). This paper describes the key components of the Hyperion calibration process that are applicable to future HSI missions. The pre-launch methods relied on then newly-developed, detector-based methods. Subsequent vicarious methods including cross-calibration with other sensors and the reflectance-based method showed significant differences from the prelaunch calibration. Such a difference demonstrated the importance of the vicarious methods as well as pointing to areas for improvement in the prelaunch methods. We also identify areas where lessons learned from Hyperion regarding

  1. A discussion of calibration techniques for evaluating binary and categorical predictive models.

    Science.gov (United States)

    Fenlon, Caroline; O'Grady, Luke; Doherty, Michael L; Dunnion, John

    2018-01-01

    Modelling of binary and categorical events is a commonly used tool to simulate epidemiological processes in veterinary research. Logistic and multinomial regression, naïve Bayes, decision trees and support vector machines are popular data mining techniques used to predict the probabilities of events with two or more outcomes. Thorough evaluation of a predictive model is important to validate its ability for use in decision-support or broader simulation modelling. Measures of discrimination, such as sensitivity, specificity and receiver operating characteristics, are commonly used to evaluate how well the model can distinguish between the possible outcomes. However, these discrimination tests cannot confirm that the predicted probabilities are accurate and without bias. This paper describes a range of calibration tests, which typically measure the accuracy of predicted probabilities by comparing them to mean event occurrence rates within groups of similar test records. These include overall goodness-of-fit statistics in the form of the Hosmer-Lemeshow and Brier tests. Visual assessment of prediction accuracy is carried out using plots of calibration and deviance (the difference between the outcome and its predicted probability). The slope and intercept of the calibration plot are compared to the perfect diagonal using the unreliability test. Mean absolute calibration error provides an estimate of the level of predictive error. This paper uses sample predictions from a binary logistic regression model to illustrate the use of calibration techniques. Code is provided to perform the tests in the R statistical programming language. The benefits and disadvantages of each test are described. Discrimination tests are useful for establishing a model's diagnostic abilities, but may not suitably assess the model's usefulness for other predictive applications, such as stochastic simulation. Calibration tests may be more informative than discrimination tests for evaluating

  2. Towards absolute laser spectroscopic CO2 isotope ratio measurements

    Science.gov (United States)

    Anyangwe Nwaboh, Javis; Werhahn, Olav; Ebert, Volker

    2017-04-01

    Knowledge of isotope composition of carbon dioxide (CO2) in the atmosphere is necessary to identify sources and sinks of this key greenhouse gas. In the last years, laser spectroscopic techniques such as cavity ring-down spectroscopy (CRDS) and tunable diode laser absorption spectroscopy (TDLAS) have been shown to perform accurate isotope ratio measurements for CO2 and other gases like water vapour (H2O) [1,2]. Typically, isotope ratios are reported in literature referring to reference materials provided by e.g. the International Atomic Energy Agency (IAEA). However, there could be some benefit if field deployable absolute isotope ratio measurement methods were developed to address issues such as exhausted reference material like the Pee Dee Belemnite (PDB) standard. Absolute isotope ratio measurements would be particularly important for situations where reference materials do not even exist. Here, we present CRDS and TDLAS-based absolute isotope ratios (13C/12C ) in atmospheric CO2. We demonstrate the capabilities of the used methods by measuring CO2 isotope ratios in gas standards. We compare our results to values reported for the isotope certified gas standards. Guide to the expression of uncertainty in measurement (GUM) compliant uncertainty budgets on the CRDS and TDLAS absolute isotope ratio measurements are presented, and traceability is addressed. We outline the current impediments in realizing high accuracy absolute isotope ratio measurements using laser spectroscopic methods, propose solutions and the way forward. Acknowledgement Parts of this work have been carried out within the European Metrology Research Programme (EMRP) ENV52 project-HIGHGAS. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. References [1] B. Kühnreich, S. Wagner, J. C. Habig,·O. Möhler, H. Saathoff, V. Ebert, Appl. Phys. B 119:177-187 (2015). [2] E. Kerstel, L. Gianfrani, Appl. Phys. B 92, 439-449 (2008).

  3. 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.

  4. Traceable Determination of the Absolute Neutron Emission Yields of UO2F2 Working Reference Materials

    International Nuclear Information System (INIS)

    LaFleur, A.M.; Swinhoe, M.T.; Mayo, D.R.; Sapp, B.A.; Croft, S.; Mayer, R.L.

    2013-06-01

    The nuclear material contained in the process equipment of a uranium enrichment plant (referred to as holdup) is an important component of the overall nuclear material inventory for the plant. Accurate quantification and verification of holdup is needed to improve international safeguards and nuclear material accountancy. This is also needed for criticality safety and waste disposition. Passive neutron and gamma-ray nondestructive assay (NDA) methods are used to measure the holdup in process equipment. A key advantage of neutron measurements is that neutrons are highly penetrating and can be measured through thick walled equipment. The dominant source of neutrons in the UO 2 F 2 holdup is from the 19 F(α, n) 22 Na reaction resulting from 234 U alpha decay when uranium is enriched. There is a considerable spread between different historic determinations of the 19 F(α, n) yield from uranium which limits the accuracy of modeling and the calibration of NDA instruments. Furthermore, the compound form and presence of water also significantly affects the neutron emission rate from the holdup. This paper describes a series of experimental measurements performed at Los Alamos National Laboratory (LANL) to determine the absolute neutron emission yield from 10 different UO 2 F 2 working reference materials (WRMs) fabricated at the Portsmouth Gaseous Diffusion Plant (PGDP). The Mini Epithermal Neutron Multiplicity Counter (Mini ENMC) and a NIST certified 252 Cf neutron source were used for these measurements. The high efficiency and short die-away time of the Mini ENMC provides the high measurement precision needed to certify the neutron emission yield. The experiment was designed to achieve sub 1% accuracy in the net counting rate on each item and to provide assurance that important factors such as instrument stability, item placement and background were well understood. The traceable neutron yields measured from the WRMs were used to determine a more accurate neutron yield

  5. Swarm's absolute magnetometer experimental vector mode, an innovative capability for space magnetometry

    DEFF Research Database (Denmark)

    Hulot, Gauthier; Vigneron, Pierre; Leger, Jean-Michel

    2015-01-01

    ESA's Swarm satellites carry a new generation of 4He absolute magnetometers (ASM), designed by CEA-Leti and developed in partnership with CNES. These instruments are the rst-ever space-born magnetometers to use a common sensor to simultaneously deliver 1Hz independent absolute scalar and vector...... be monitored from space with such absolute vector magnetometers....... readings of the magnetic eld. Since launch, these ASMs provided very high accuracy scalar eld data, as nominally required for the mission, together with experimental vector eld data. Here, we compare geomagnetic eld models built from such ASM-only data with models built from the mission's nominal 1Hz data...

  6. Beam-Based Calibration of the Electron Energy in the Fermilab Electron Cooler

    CERN Document Server

    Seletsky, Sergey

    2005-01-01

    Electron cooling of 8.9 GeV antiprotons in the Fermilab's Recycler ring requires precise matching of electron and antiproton velocities. While the final match can be done by optimization of the cooling process, for the very first cooling one should rely on the knowledge of absolute values of electron and antiproton energies. The upper limit for the energy uncertainty of both beams is determined by the Recycler's momentum aperture and is equal to 0.3%. The paper discusses a method of the electron energy calibration that is based on the measurement of the electron's Larmor wavelength in the field of the cooling section solenoid. The method was tested in an 18 m long cooling section prototype with 3.5 MeV electrons. An accuracy of 0.3% was demonstrated.

  7. Calibration of nuclides by gamma-gamma sum peak coincidence counting

    International Nuclear Information System (INIS)

    Guevara, E.A.

    1986-01-01

    The feasibility of extending sum peak coincidence counting to the direct calibration of gamma-ray emitters having particular decay schemes was investigated, also checkings of the measurement accuracy, by comparing with more precise beta-gamma coincidence counting have been performed. New theoretical studies and experiments were developed, demonstrating the reliability of the procedure. Uncertainties of less than one percent were obtained when certain radioactive sources were measured. The application of the procedure to 60 Co, 22 Na, 47 Ca and 148 Pm was studied. Theoretical bases of sum peak coincidence counting were set in order to extend it as an alternative method for absolute activity determination. In this respect, theoretical studies were performed for positive and negative beta decay, and electron capture, either accompanied or unaccompanied by coincident gamma rays. They include decay schemes containing up to three daughter nuclide excited levels, for different geometrical configurations. Equations are proposed for a possible generalization of the procedure. (M.E.L.) [es

  8. Absolute distance measurements using two-mode laser telemetry

    Science.gov (United States)

    Lintz, Michel.; Courde, C.; Brillet, A.; Man, C. N.

    2017-11-01

    A novel laser ranging method is described that uses a two-mode laser source, and detection of the phase of the return beam. The design eliminates the cyclic error usually associated with phase measurements and provides unambiguous, absolute distance determination. Measurements of an ≍ 8m path are obtained at a beat frequency of 13 GHz. We analyse the ≍1 μm stability of the data obtained with this preliminary implementation, and expect that an improved version will allow accuracies well below 1 μm, for the kilometer-scale distances involved in satellite formation flight.

  9. Absolutely summing multilinear operators: a Panorama | Pellegrino ...

    African Journals Online (AJOL)

    This paper has a twofold purpose: to present an overview of the theory of absolutely summing operators and its different generalizations for the multilinear setting, and to sketch the beginning of a research project related to an objective search of “perfect” multilinear extensions of the ideal of absolutely summing operators.

  10. MEAN OF MEDIAN ABSOLUTE DERIVATION TECHNIQUE MEAN ...

    African Journals Online (AJOL)

    eobe

    The accurate estimation of noise variance in an image is the first important stage ... lung image was lung image was developed. developed. developed. The development of mean of median absolute derivation technique development of mean of median absolute .... that are non-real numbers during initial processing.

  11. Quantum nonequilibrium equalities with absolute irreversibility

    Science.gov (United States)

    Funo, Ken; Murashita, Yûto; Ueda, Masahito

    2015-07-01

    We derive quantum nonequilibrium equalities in absolutely irreversible processes. Here by absolute irreversibility we mean that in the backward process the density matrix does not return to the subspace spanned by those eigenvectors that have nonzero weight in the initial density matrix. Since the initial state of a memory and the postmeasurement state of the system are usually restricted to a subspace, absolute irreversibility occurs during the measurement and feedback processes. An additional entropy produced in absolutely irreversible processes needs to be taken into account to derive nonequilibrium equalities. We discuss a model of a feedback control on a qubit system to illustrate the obtained equalities. By introducing N heat baths each composed of a qubit and letting them interact with the system, we show how the entropy reduction via feedback control can be converted into work. An explicit form of extractable work in the presence of absolute irreversibility is given.

  12. Sensor modelling and camera calibration for close-range photogrammetry

    Science.gov (United States)

    Luhmann, Thomas; Fraser, Clive; Maas, Hans-Gerd

    2016-05-01

    Metric calibration is a critical prerequisite to the application of modern, mostly consumer-grade digital cameras for close-range photogrammetric measurement. This paper reviews aspects of sensor modelling and photogrammetric calibration, with attention being focussed on techniques of automated self-calibration. Following an initial overview of the history and the state of the art, selected topics of current interest within calibration for close-range photogrammetry are addressed. These include sensor modelling, with standard, extended and generic calibration models being summarised, along with non-traditional camera systems. Self-calibration via both targeted planar arrays and targetless scenes amenable to SfM-based exterior orientation are then discussed, after which aspects of calibration and measurement accuracy are covered. Whereas camera self-calibration is largely a mature technology, there is always scope for additional research to enhance the models and processes employed with the many camera systems nowadays utilised in close-range photogrammetry.

  13. LIDAR TS for ITER core plasma. Part III: calibration and higher edge resolution

    Science.gov (United States)

    Nielsen, P.; Gowers, C.; Salzmann, H.

    2017-12-01

    Calibration, after initial installation, of the proposed two wavelength LIDAR Thomson Scattering System requires no access to the front end and does not require a foreign gas fill for Raman scattering. As already described, the variation of solid angle of collection with scattering position is a simple geometrical variation over the unvignetted region. The additional loss over the vignetted region can easily be estimated and in the case of a small beam dump located between the Be tiles, it is within the specified accuracy of the density. The only additional calibration is the absolute spectral transmission of the front-end optics. Over time we expect the transmission of the two front-end mirrors to suffer a deterioration mainly due to depositions. The reduction in transmission is likely to be worse towards the blue end of the scattering spectrum. It is therefore necessary to have a method to monitor such changes and to determine its spectral variation. Standard methods use two lasers at different wavelength with a small time separation. Using the two-wavelength approach, a method has been developed to determine the relative spectral variation of the transmission loss, using simply the measured signals in plasmas with peak temperatures of 4–6 keV . Comparing the calculated line integral of the fitted density over the full chord to the corresponding interferometer data we also have an absolute calibration. At the outer plasma boundary, the standard resolution of the LIDAR Thomson Scattering System is not sufficient to determine the edge gradient in an H-mode plasma. However, because of the step like nature of the signal here, it is possible to carry out a deconvolution of the scattered signals, thereby achieving an effective resolution of ~ 1–2 cm in the outer 10–20 cm.

  14. Accuracy of a continuous glucose monitoring system in dogs and cats with diabetic ketoacidosis.

    Science.gov (United States)

    Reineke, Erica L; Fletcher, Daniel J; King, Lesley G; Drobatz, Kenneth J

    2010-06-01

    (1) To determine the ability of a continuous interstitial glucose monitoring system (CGMS) to accurately estimate blood glucose (BG) in dogs and cats with diabetic ketoacidosis. (2) To determine the effect of perfusion, hydration, body condition score, severity of ketosis, and frequency of calibration on the accuracy of the CGMS. Prospective study. University Teaching Hospital. Thirteen dogs and 11 cats diagnosed with diabetic ketoacidosis were enrolled in the study within 24 hours of presentation. Once BG dropped below 22.2 mmol/L (400 mg/dL), a sterile flexible glucose sensor was placed aseptically in the interstitial space and attached to the continuous glucose monitoring device for estimation of the interstitial glucose every 5 minutes. BG measurements were taken with a portable BG meter every 2-4 hours at the discretion of the primary clinician and compared with CGMS glucose measurements. The CGMS estimates of BG and BG measured on the glucometer were strongly associated regardless of calibration frequency (calibration every 8 h: r=0.86, Pglucose measurements was found but was not associated with body condition, perfusion, or degree of ketosis. A weak association between hydration status of the patient as assessed with the visual analog scale and absolute percent error (Spearman's rank correlation, rho=-0.079, 95% CI=-0.15 to -0.01, P=0.03) was found, with the device being more accurate in the more hydrated patients. The CGMS provides clinically accurate estimates of BG in patients with diabetic ketoacidosis.

  15. Laser Calibration of the ATLAS Tile Calorimeter

    CERN Document Server

    Di Gregorio, Giulia; The ATLAS collaboration

    2017-01-01

    High performance stability of the ATLAS Tile Calorimeter is achieved with a set of calibration procedures. One step of the calibration procedure is based on measurements of the response stability to laser excitation of the PMTs that are used to readout the calorimeter cells. A facility to study in lab the PMT stability response is operating in the PISA-INFN laboratories since 2015. Goals of the tests in lab are to study the time evolution of the PMT response to reproduce and to understand the origin of the response drifts seen with the PMT mounted on the Tile calorimeter in its normal operating during LHC run I and run II. A new statistical approach was developed to measure drift of the absolute gain. This approach was applied to both the ATLAS laser calibration data and to data collected in the Pisa local laboratory. The preliminary results from these two studies are shown.

  16. In situ vector calibration of magnetic observatories

    Directory of Open Access Journals (Sweden)

    A. Gonsette

    2017-09-01

    Full Text Available The goal of magnetic observatories is to measure and provide a vector magnetic field in a geodetic coordinate system. For that purpose, instrument set-up and calibration are crucial. In particular, the scale factor and orientation of a vector magnetometer may affect the magnetic field measurement. Here, we highlight the baseline concept and demonstrate that it is essential for data quality control. We show how the baselines can highlight a possible calibration error. We also provide a calibration method based on high-frequency absolute measurements. This method determines a transformation matrix for correcting variometer data suffering from scale factor and orientation errors. We finally present a practical case where recovered data have been successfully compared to those coming from a reference magnetometer.

  17. Thermoluminescence dating (TL-dating): measurement and accuracy factors in archaeological dating of ceramic base materials

    International Nuclear Information System (INIS)

    Wan Saffiey Wan Abdullah

    2004-01-01

    Thermoluminescence dating is one of the known techniques that have been established in many laboratories across the region. This technique is capable of dating the archaeological ceramic base materials and provide an absolute measurement with an accuracy of ±15%. The study involves the dating of pottery from a historical site at Sungai Mas, Mukim Kota, Daerah Kuala Muda, Kedah. Pieces of broken pottery of archaeological sample excavated by the Museum Department and Antiquity (JMA) have been dated using the thermoluminescence detector (TLD) techniques at MINT laboratory. A TLD dosemeter of LiF chips is used for the measurement of background and sample dose measurement. The preparation of sample and the calibration techniques for the estimation of palaedose or dose presented in the sample since distant past is established. Results indicate that the samples are in the era of civilization from 200 BP to 1600 BP. Error factors associated in the measurement procedures were identified and discussed. (Author)

  18. Absolute luminosity measurement at LHCb with beam-gas imaging

    CERN Document Server

    Barschel, C

    2013-01-01

    A novel technique to measure the absolute luminosity at the Large Hadron Collider (LHC) using beam-gas interactions has been successfully used in the LHCb experiment. A gas injection device (SMOG) has been installed in the LHCb experiment to increase the pressure around the interaction point during dedicated fills. The Beam-Gas Imaging method (BGI) has now the potential to surpass the accuracy of the commonly used *van der Meer scan* method (VDM). The technique has been used in 10 LHC fills during 2012 including and also provided a first luminosity measurement for proton-lead collisions. This talk presents the principles of the gas injection and the improvements reached with the increased pressure. Furthermore the gas injection increased the accuracy measurement of the so-called ghost charges and also intensities per bunch. Those uncertainties are becoming the dominating factor because the uncertainty on the total beam current have been reduced.

  19. An Improved Photometric Calibration of the Sloan Digital Sky Survey Imaging Data

    Energy Technology Data Exchange (ETDEWEB)

    Padmanabhan, Nikhil; Schlegel, D.J.; Finkbeiner, D.P.; Barentine, J.C.; Blanton, M.R.; Brewington, H.J.; Gunn, J.E.; Harvanek, M.; Hogg, D.W.; Ivezic, Z.; Johnston, D.; /LBL, Berkeley /Princeton U. /Harvard-Smithsonian Ctr. Astrophys. /Texas U., Astron. Dept. /Apache Point Observ. /New York U. /Washington U., Seattle, Astron. Dept. /Caltech, JPL

    2007-03-01

    We present an algorithm to photometrically calibrate wide field optical imaging surveys, that simultaneously solves for the calibration parameters and relative stellar fluxes using overlapping observations. The algorithm decouples the problem of ''relative'' calibrations from that of ''absolute'' calibrations; the absolute calibration is reduced to determining a few numbers for the entire survey. We pay special attention to the spatial structure of the calibration errors, allowing one to isolate particular error modes in downstream analyses. Applying this to the Sloan Digital Sky Survey imaging data, we achieve {approx}1% relative calibration errors across 8500 deg{sup 2} in griz; the errors are {approx}2% for the u band. These errors are dominated by unmodeled atmospheric variations at Apache Point Observatory.

  20. A Technique for Binocular Stereo Vision System Calibration by the Nonlinear Optimization and Calibration Points with Accurate Coordinates

    International Nuclear Information System (INIS)

    Chen, H; Ye, D; Che, R S; Chen, G

    2006-01-01

    With the increasing need for higher accuracy measurement in computer vision, the precision of camera calibration is a more important factor. The objective of stereo camera calibration is to estimate the intrinsic and extrinsic parameters of each camera. We presented a high-accurate technique to calibrate binocular stereo vision system having been mounted the locations and attitudes, which was realized by combining nonlinear optimization method with accurate calibration points. The calibration points with accurate coordinates, were formed by an infrared LED moved with three-dimensional coordinate measurement machine, which can ensure indeterminacy of measurement is 1/30000. By using bilinear interpolation square-gray weighted centroid location algorithm, the imaging centers of the calibration points can be accurately determined. The accuracy of the calibration is measured in terms of the accuracy in the reconstructing calibration points through triangulation, the mean distance between reconstructing point and given calibration point is 0.039mm. The technique can satisfy the goals of measurement and camera accurate calibration

  1. Application of x-ray fluorescence (XRF) absolute analysis method for silica refractories

    International Nuclear Information System (INIS)

    Asakura, Hideo; Yamada, Yasujiro; Kansai, Kouhei; Tomatsu, Ichirou; Murata, Mamoru

    2015-01-01

    X-ray fluorescence (XRF) analysis is a rapid and precise quantitative analytical method for the determination of major and trace elements in many industries and academics. XRF analytical values are relative due to the use of the calibration curves calculated from measuring the reference standard materials such as Japanese Refractory Reference Materials (JRRM) series with certified values determined by wet chemical analysis. The development of the XRF analytical method from relative to absolute analysis will help much to determine the absolute values of samples from the fields where reference standard samples have not been prepared, and thus can be applied widely in many industries. The implement of the absolute XRF analysis for silica refractories requires high purity reagents and/or reference standard solution for the binary basic calibration curve, and theoretical matrix correction coefficients for the multi-components silica refractories analysis. The reproducibility and repeatability of this method for Al 2 O 3 5 mass% sample were 0.009 and 0.006 mass% in Al 2 O 3 and showed better values that those of ICP-AES recognized as an absolute method in JIS R 2212-2, which yielded 0.028 and 0.031 mass%, respectively. The XRF absolute analysis for JRRM 200 series, 201a and 205a does not show a bias but coincides with their certified values. (author)

  2. Application of composite small calibration objects in traffic accident scene photogrammetry.

    Science.gov (United States)

    Chen, Qiang; Xu, Hongguo; Tan, Lidong

    2015-01-01

    In order to address the difficulty of arranging large calibration objects and the low measurement accuracy of small calibration objects in traffic accident scene photogrammetry, a photogrammetric method based on a composite of small calibration objects is proposed. Several small calibration objects are placed around the traffic accident scene, and the coordinate system of the composite calibration object is given based on one of them. By maintaining the relative position and coplanar relationship of the small calibration objects, the local coordinate system of each small calibration object is transformed into the coordinate system of the composite calibration object. The two-dimensional direct linear transformation method is improved based on minimizing the reprojection error of the calibration points of all objects. A rectified image is obtained using the nonlinear optimization method. The increased accuracy of traffic accident scene photogrammetry using a composite small calibration object is demonstrated through the analysis of field experiments and case studies.

  3. Cumulative sum quality control for calibrated breast density measurements

    International Nuclear Information System (INIS)

    Heine, John J.; Cao Ke; Beam, Craig

    2009-01-01

    Purpose: Breast density is a significant breast cancer risk factor. Although various methods are used to estimate breast density, there is no standard measurement for this important factor. The authors are developing a breast density standardization method for use in full field digital mammography (FFDM). The approach calibrates for interpatient acquisition technique differences. The calibration produces a normalized breast density pixel value scale. The method relies on first generating a baseline (BL) calibration dataset, which required extensive phantom imaging. Standardizing prospective mammograms with calibration data generated in the past could introduce unanticipated error in the standardized output if the calibration dataset is no longer valid. Methods: Sample points from the BL calibration dataset were imaged approximately biweekly over an extended timeframe. These serial samples were used to evaluate the BL dataset reproducibility and quantify the serial calibration accuracy. The cumulative sum (Cusum) quality control method was used to evaluate the serial sampling. Results: There is considerable drift in the serial sample points from the BL calibration dataset that is x-ray beam dependent. Systematic deviation from the BL dataset caused significant calibration errors. This system drift was not captured with routine system quality control measures. Cusum analysis indicated that the drift is a sign of system wear and eventual x-ray tube failure. Conclusions: The BL calibration dataset must be monitored and periodically updated, when necessary, to account for sustained system variations to maintain the calibration accuracy.

  4. Cumulative sum quality control for calibrated breast density measurements

    Energy Technology Data Exchange (ETDEWEB)

    Heine, John J.; Cao Ke; Beam, Craig [Cancer Prevention and Control Division, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, Florida 33612 (United States); Division of Epidemiology and Biostatistics, School of Public Health, University of Illinois at Chicago, 1603 W. Taylor St., Chicago, Illinois 60612 (United States)

    2009-12-15

    Purpose: Breast density is a significant breast cancer risk factor. Although various methods are used to estimate breast density, there is no standard measurement for this important factor. The authors are developing a breast density standardization method for use in full field digital mammography (FFDM). The approach calibrates for interpatient acquisition technique differences. The calibration produces a normalized breast density pixel value scale. The method relies on first generating a baseline (BL) calibration dataset, which required extensive phantom imaging. Standardizing prospective mammograms with calibration data generated in the past could introduce unanticipated error in the standardized output if the calibration dataset is no longer valid. Methods: Sample points from the BL calibration dataset were imaged approximately biweekly over an extended timeframe. These serial samples were used to evaluate the BL dataset reproducibility and quantify the serial calibration accuracy. The cumulative sum (Cusum) quality control method was used to evaluate the serial sampling. Results: There is considerable drift in the serial sample points from the BL calibration dataset that is x-ray beam dependent. Systematic deviation from the BL dataset caused significant calibration errors. This system drift was not captured with routine system quality control measures. Cusum analysis indicated that the drift is a sign of system wear and eventual x-ray tube failure. Conclusions: The BL calibration dataset must be monitored and periodically updated, when necessary, to account for sustained system variations to maintain the calibration accuracy.

  5. Retained Gas Sampler Calibration and Simulant Tests

    Energy Technology Data Exchange (ETDEWEB)

    CRAWFORD, B.A.

    2000-01-05

    This test plan provides a method for calibration of the retained gas sampler (RGS) for ammonia gas analysis. Simulant solutions of ammonium hydroxide at known concentrations will be diluted with isotopically labeled 0.04 M ammonium hydroxide solution. Sea sand solids will also be mixed with ammonium hydroxide solution and diluent to determine the accuracy of the system for ammonia gas analysis.

  6. Mine neutralisation with small calibre projectile impact

    NARCIS (Netherlands)

    Dijkstra, M.H.; Meulman, J.H.

    2005-01-01

    The Dutch Ministry of Defence has asked TNO to study mine neutralisation by small calibre projectile impact. This method would not demand the close approach of a suspected object. A single shot with a high accuracy weapon at a large stand-off will eliminate the danger and will allow for close

  7. Retained Gas Sampler Calibration and Simulant Tests

    International Nuclear Information System (INIS)

    CRAWFORD, B.A.

    2000-01-01

    This test plan provides a method for calibration of the retained gas sampler (RGS) for ammonia gas analysis. Simulant solutions of ammonium hydroxide at known concentrations will be diluted with isotopically labeled 0.04 M ammonium hydroxide solution. Sea sand solids will also be mixed with ammonium hydroxide solution and diluent to determine the accuracy of the system for ammonia gas analysis

  8. The absolute environmental performance of buildings

    DEFF Research Database (Denmark)

    Brejnrod, Kathrine Nykjær; Kalbar, Pradip; Petersen, Steffen

    2017-01-01

    sustainability for the standard house were proposed focusing on three measures: minimizing environmental impacts from building construction, minimizing impacts from energy consumption during use phase, and reducing the living area per person. In an intermediate path, absolute sustainability can be obtained...... by reducing the impacts from construction by 89%, use phase energy consumption by 80%, and the living area by 60%.......Our paper presents a novel approach for absolute sustainability assessment of a building's environmental performance. It is demonstrated how the absolute sustainable share of the earth carrying capacity of a specific building type can be estimated using carrying capacity based normalization factors...

  9. The absolute frequency of the 87Sr optical clock transition

    DEFF Research Database (Denmark)

    Campbell, Gretchen K.; Ludlow, Andrew D.; Blatt, Sebastian

    2008-01-01

    The absolute frequency of the 1S0–3P0 clock transition of 87Sr has been measured to be 429 228 004 229 873.65 (37) Hz using lattice-confined atoms, where the fractional uncertainty of 8.6 × 10-16 represents one of the most accurate measurements of an atomic transition frequency to date. After...... a detailed study of systematic effects, which reduced the total systematic uncertainty of the Sr lattice clock to 1.5 × 10-16, the clock frequency is measured against a hydrogen maser which is simultaneously calibrated to the US primary frequency standard, the NIST Cs fountain clock, NIST-F1. The comparison...... is made possible using a femtosecond laser based optical frequency comb to phase coherently connect the optical and microwave spectral regions and by a 3.5 km fibre transfer scheme to compare the remotely located clock signals....

  10. Attempts to Improve Absolute Quantification of Cerebral Blood Flow in Dynamic Susceptibility Contrast Magnetic Resonance Imaging: A Simplified T1-Weighted Steady-State Cerebral Blood Volume Approach

    International Nuclear Information System (INIS)

    Wirestam, R.; Knutsson, L.; Risberg, J.; Boerjesson, S.; Larsson, E.M.; Gustafson, L.; Passant, U.; Staahlberg, F.

    2007-01-01

    Background: Attempts to retrieve absolute values of cerebral blood flow (CBF) by dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) have typically resulted in overestimations. Purpose: To improve DSC-MRI CBF estimates by calibrating the DSC-MRI-based cerebral blood volume (CBV) with a corresponding T1-weighted (T1W) steady-state (ss) CBV estimate. Material and Methods: 17 volunteers were investigated by DSC-MRI and 133Xe SPECT. Steady-state CBV calculation, assuming no water exchange, was accomplished using signal values from blood and tissue, before and after contrast agent, obtained by T1W spin-echo imaging. Using steady-state and DSC-MRI CBV estimates, a calibration factor K = CBV(ss)/CBV(DSC) was obtained for each individual. Average whole-brain CBF(DSC) was calculated, and the corrected MRI-based CBF estimate was given by CBF(ss) = KxCBF(DSC). Results: Average whole-brain SPECT CBF was 40.1±6.9 ml/min 100 g, while the corresponding uncorrected DSC-MRI-based value was 69.2±13.8 ml/mi 100 g. After correction with the calibration factor, a CBF(ss) of 42.7±14.0 ml/min 100 g was obtained. The linear fit to CBF(ss)-versus-CBF(SPECT) data was close to proportionality (R 0.52). Conclusion: Calibration by steady-state CBV reduced the population average CBF to a reasonable level, and a modest linear correlation with the reference 133Xe SPECT technique was observed. Possible explanations for the limited accuracy are, for example, large-vessel partial-volume effects, low post-contrast signal enhancement in T1W images, and water-exchange effects

  11. Scintillator's sensitivity calibration method in synchrotron radiation facility

    International Nuclear Information System (INIS)

    He Xiao'an; Du Huabing; Li Chaoguang; Yi Rongqing; Xiao Tiqiao

    2012-01-01

    Researches on scintillator's sensitivity method has been carried out recently in Shanghai synchrotron radiation facility. By some experimental researches in light source and detector's linearity, it built a new method for calibrating scintillator's sensitivity. Finally, calibration results were acquired by theory simulation of experimental data which were in accordance with radioactive source methods results, and the new method improved the data accuracy. (authors)

  12. Stormwater quality calibration by SWMM: A case study in Northern ...

    African Journals Online (AJOL)

    The process of hydraulic and quality calibration is described and the values of the adjusted parameters are presented, comparing them with those obtained from other studies. The calibrated model simulated accurately the hydrograph\\'s shape and the time of presentation of the peak flows. The accuracy of adjustment of the ...

  13. Stormwater quality calibration by SWMM: A case study in Northern ...

    African Journals Online (AJOL)

    2005-05-10

    May 10, 2005 ... The process of hydraulic and quality calibration is described and the values of the adjusted parameters are presented, comparing them with those obtained from other studies. The calibrated model simulated accurately the hydrograph's shape and the time of presentation of the peak flows. The accuracy of ...

  14. Calibration of the Atlas electromagnetic calorimeter. Search for the Higgs boson in its invisible decays; Etalonnage du calorimetre electromagnetique d'ATLAS. Recherche du boson de Higgs dans ses desintegrations invisibles

    Energy Technology Data Exchange (ETDEWEB)

    Neukermans, L

    2002-05-01

    The most promising channels for an intermediate mass Higgs boson discovery at LHC are leptonic and photonic decays. Therefore, a good uniformity of response of the electromagnetic calorimeter is required to reach the 0.7% constant term needed. This thesis deals with the absolute calibration of this detector. An electrical description of the calibration system, the detector and its read-out chain has been made for a better comprehension of the signal pulse shapes. A method, using a convolution of the calibration waveforms, has been developed to predict physics response, leading to absolute calibration. The level of accuracy obtained allows to reach the 0.3% contribution to the constant term required. Test beam analysis of a prototype module showed the performance of the electromagnetic calorimeter in terms of local resolution and linearity. A uniformity study has been made, leading to a 0.8% dispersion on a {delta}{eta} x {delta}{phi} = 1.2 x 0.75 area. In a second part, the observability of an invisible Higgs boson produced via weak boson fusion at the LHC is presented. A level 1 trigger strategy for this purely jet and missing E{sub T} final states is discussed. A method to measure the level of background using physics events is presented. This analysis shows that an invisible branching ratio of 25% could be reached at 95% CL with only 30 fb{sup -1} for a Higgs boson mass of 120 GeV/c{sup 2}. (author)

  15. ASTEROID ABSOLUTE MAGNITUDES V10.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Absolute magnitudes and slopes, mostly IAU-adopted with exceptions noted, for all asteroids numbered as of the 2006 March 14 batch of Minor Planet Circulars.

  16. ASTEROID ABSOLUTE MAGNITUDES V11.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Absolute magnitudes and slopes, mostly IAU-adopted with exceptions noted, for all asteroids numbered as of the 2007 April 2 batch of Minor Planet Circulars.

  17. ASTEROID ABSOLUTE MAGNITUDES V12.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Absolute magnitudes and slopes, mostly IAU-adopted with exceptions noted, for all asteroids numbered as of the 2008 April 20 batch of Minor Planet Circulars.

  18. ASTEROID ABSOLUTE MAGNITUDES V7.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set tabulates the IAU-adopted absolute V magnitude and slope parameter for all numbered asteroids as of the given stop date. The data set is updated yearly.

  19. ASTEROID ABSOLUTE MAGNITUDES V9.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Absolute magnitudes and slopes, mostly IAU-adopted with exceptions noted, for all asteroids numbered as of the 2005 April 7 batch of Minor Planet Circulars.

  20. ASTEROID ABSOLUTE MAGNITUDES V8.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Absolute magnitudes and slopes, mostly IAU-adopted with exceptions noted, for all asteroids numbered as of the 2004 April 15 batch of Minor Planet Circulars

  1. Micrometry combined with profile mapping for the absolute measurement of Integrated Column Density (ICD) and for accurate X-ray mass attenuation coefficients using XERT

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M. Tauhidul; Rae, Nicholas A.; Glover, Jack L.; Barnea, Zwi [School of Physics, University of Melbourne, Victoria 3010 (Australia); Chantler, Christopher T., E-mail: chantler@physics.unimelb.edu.a [School of Physics, University of Melbourne, Victoria 3010 (Australia)

    2010-07-21

    Absolute values of the column densities [{rho}t]{sub c} of four gold foils were measured using micrometry combined with the 2D X-ray attenuation profile. The absolute calibration of [{rho}t]{sub c} was made with a reference foil and the [{rho}t]{sub c} of other foils were determined following the thickness transfer method. By this method, we obtain absolute calibration to 0.1% or better which was not possible using only the X-ray map of a single foil over its central region.

  2. Absolutely uniform illumination of laser fusion pellets

    International Nuclear Information System (INIS)

    Schmitt, A.J.

    1984-01-01

    Absolutely uniform illumination of spherical laser fusion pellets is possible when the energy deposition from a single beam is given by a simple cos 2 theta distribution. Conditions can be derived for which the laser beam targeting angles allow this absolute illumination uniformity. Configurations based upon the cube and higher order Platonic solids satisfy the constraints, as well as an infinite class of other less symmetric configurations

  3. Absolutely uniform illumination of laser fusion pellets

    International Nuclear Information System (INIS)

    Schmitt, A.J.

    1984-01-01

    Absolutely uniform illumination of spherical laser fusion pellets is possible when the energy deposition from a single laser beam is given by a simple cos 2 theta distribution. Conditions can be derived for which the laser beam targeting angles allow this absolute illumination uniformity. Configurations based upon the cube and higher order Platonic solids satisfy the constraints, as well as infinite class of other less symmetric configurations

  4. Absolute spectrophotometry of Nova Cygni 1975

    International Nuclear Information System (INIS)

    Kontizas, E.; Kontizas, M.; Smyth, M.J.

    1976-01-01

    Radiometric photoelectric spectrophotometry of Nova Cygni 1975 was carried out on 1975 August 31, September 2, 3. α Lyr was used as reference star and its absolute spectral energy distribution was used to reduce the spectrophotometry of the nova to absolute units. Emission strengths of Hα, Hβ, Hγ (in W cm -2 ) were derived. The Balmer decrement Hα:Hβ:Hγ was compared with theory, and found to deviate less than had been reported for an earlier nova. (author)

  5. COMPARISON OF METHODS FOR GEOMETRIC CAMERA CALIBRATION

    Directory of Open Access Journals (Sweden)

    J. Hieronymus

    2012-09-01

    Full Text Available Methods for geometric calibration of cameras in close-range photogrammetry are established and well investigated. The most common one is based on test-fields with well-known pattern, which are observed from different directions. The parameters of a distortion model are calculated using bundle-block-adjustment-algorithms. This methods works well for short focal lengths, but is essentially more problematic to use with large focal lengths. Those would require very large test-fields and surrounding space. To overcome this problem, there is another common method for calibration used in remote sensing. It employs measurements using collimator and a goniometer. A third calibration method uses diffractive optical elements (DOE to project holograms of well known pattern. In this paper these three calibration methods are compared empirically, especially in terms of accuracy. A camera has been calibrated with those methods mentioned above. All methods provide a set of distortion correction parameters as used by the photogrammetric software Australis. The resulting parameter values are very similar for all investigated methods. The three sets of distortion parameters are crosscompared against all three calibration methods. This is achieved by inserting the gained distortion parameters as fixed input into the calibration algorithms and only adjusting the exterior orientation. The RMS (root mean square of the remaining image coordinate residuals are taken as a measure of distortion correction quality. There are differences resulting from the different calibration methods. Nevertheless the measure is small for every comparison, which means that all three calibration methods can be used for accurate geometric calibration.

  6. Guidelines on calibration of neutron measuring devices

    International Nuclear Information System (INIS)

    Burger, G.

    1988-01-01

    The International Atomic Energy Agency and the World Health Organization have agreed to establish an IAEA/WHO Network of Secondary Standard Dosimetry Laboratories (SSDLs) in order to improve accuracy in applied radiation dosimetry throughout the world. These SSDLs must be equipped with, and maintain, secondary standard instruments, which have been calibrated against primary standards, and must be nominated by their governments for membership of the network. The majority of the existing SSDLs were established primarily to work with photon radiation (X-rays and gamma rays). Neutron sources are, however, increasingly being applied in industrial processes, research, nuclear power development and radiation biology and medicine. Thus, it is desirable that the SSDLs in countries using neutron sources on a regular basis should also fulfil the minimum requirements to calibrate neutron measuring devices. It is the primary purpose of this handbook to provide guidance on calibration of instruments for radiation protection. A calibration laboratory should also be in a position to calibrate instrumentation being used for the measurement of kerma and absorbed dose and their corresponding rates. This calibration is generally done with photons. In addition, since each neutron field is usually contaminated by photons produced in the source or by scatter in the surrounding media, neutron protection instrumentation has to be tested with respect to its intrinsic photon response. The laboratory will therefore need to possess equipment for photon calibration. This publication deals primarily with methods of applying radioactive neutron sources for calibration of instrumentation, and gives an indication of the space, manpower and facilities needed to fulfil the minimum requirements of a calibration laboratory for neutron work. It is intended to serve as a guide for centres about to start on neutron dosimetry standardization and calibration. 94 refs, 8 figs, 12 tabs

  7. Optimal Design of the Absolute Positioning Sensor for a High-Speed Maglev Train and Research on Its Fault Diagnosis

    OpenAIRE

    Junge Zhang; Song Xue; Zhiqiang Long; Dapeng Zhang

    2012-01-01

    This paper studies an absolute positioning sensor for a high-speed maglev train and its fault diagnosis method. The absolute positioning sensor is an important sensor for the high-speed maglev train to accomplish its synchronous traction. It is used to calibrate the error of the relative positioning sensor which is used to provide the magnetic phase signal. On the basis of the analysis for the principle of the absolute positioning sensor, the paper describes the design of the sending and rece...

  8. Error analysis in newborn screening: can quotients support the absolute values?

    Science.gov (United States)

    Arneth, Borros; Hintz, Martin

    2017-03-01

    Newborn screening is performed using modern tandem mass spectrometry, which can simultaneously detect a variety of analytes, including several amino acids and fatty acids. Tandem mass spectrometry measures the diagnostic parameters as absolute concentrations and produces fragments which are used as markers of specific substances. Several prominent quotients can also be derived, which are quotients of two absolute measured concentrations. In this study, we determined the precision of both the absolute concentrations and the derived quotients. First, the measurement error of the absolute concentrations and the measurement error of the ratios were practically determined. Then, the Gaussian theory of error calculation was used. Finally, these errors were compared with one another. The practical analytical accuracies of the quotients were significantly higher (e.g., coefficient of variation (CV) = 5.1% for the phenylalanine to tyrosine (Phe/Tyr) quotient and CV = 5.6% for the Fisher quotient) than the accuracies of the absolute measured concentrations (mean CVs = 12%). According to our results, the ratios are analytically correct and, from an analytical point of view, can support the absolute values in finding the correct diagnosis.

  9. Landsat-8 Thermal Infrared Sensor (TIRS) Vicarious Radiometric Calibration

    Science.gov (United States)

    Barsi, Julia A.; Shott, John R.; Raqueno, Nina G.; Markham, Brian L.; Radocinski, Robert G.

    2014-01-01

    Launched in February 2013, the Landsat-8 carries on-board the Thermal Infrared Sensor (TIRS), a two-band thermal pushbroom imager, to maintain the thermal imaging capability of the Landsat program. The TIRS bands are centered at roughly 10.9 and 12 micrometers (Bands 10 and 11 respectively). They have 100 m spatial resolution and image coincidently with the Operational Land Imager (OLI), also on-board Landsat-8. The TIRS instrument has an internal calibration system consisting of a variable temperature blackbody and a special viewport with which it can see deep space; a two point calibration can be performed twice an orbit. Immediately after launch, a rigorous vicarious calibration program was started to validate the absolute calibration of the system. The two vicarious calibration teams, NASA/Jet Propulsion Laboratory (JPL) and the Rochester Institute of Technology (RIT), both make use of buoys deployed on large water bodies as the primary monitoring technique. RIT took advantage of cross-calibration opportunity soon after launch when Landsat-8 and Landsat-7 were imaging the same targets within a few minutes of each other to perform a validation of the absolute calibration. Terra MODIS is also being used for regular monitoring of the TIRS absolute calibration. The buoy initial results showed a large error in both bands, 0.29 and 0.51 W/sq m·sr·micrometers or -2.1 K and -4.4 K at 300 K in Band 10 and 11 respectively, where TIRS data was too hot. A calibration update was recommended for both bands to correct for a bias error and was implemented on 3 February 2014 in the USGS/EROS processing system, but the residual variability is still larger than desired for both bands (0.12 and 0.2 W/sq m·sr·micrometers or 0.87 and 1.67 K at 300 K). Additional work has uncovered the source of the calibration error: out-of-field stray light. While analysis continues to characterize the stray light contribution, the vicarious calibration work proceeds. The additional data have

  10. Landsat-8 Thermal Infrared Sensor (TIRS Vicarious Radiometric Calibration

    Directory of Open Access Journals (Sweden)

    Julia A. Barsi

    2014-11-01

    Full Text Available Launched in February 2013, the Landsat-8 carries on-board the Thermal Infrared Sensor (TIRS, a two-band thermal pushbroom imager, to maintain the thermal imaging capability of the Landsat program. The TIRS bands are centered at roughly 10.9 and 12 μm (Bands 10 and 11 respectively. They have 100 m spatial resolution and image coincidently with the Operational Land Imager (OLI, also on-board Landsat-8. The TIRS instrument has an internal calibration system consisting of a variable temperature blackbody and a special viewport with which it can see deep space; a two point calibration can be performed twice an orbit. Immediately after launch, a rigorous vicarious calibration program was started to validate the absolute calibration of the system. The two vicarious calibration teams, NASA/Jet Propulsion Laboratory (JPL and the Rochester Institute of Technology (RIT, both make use of buoys deployed on large water bodies as the primary monitoring technique. RIT took advantage of cross-calibration opportunity soon after launch when Landsat-8 and Landsat-7 were imaging the same targets within a few minutes of each other to perform a validation of the absolute calibration. Terra MODIS is also being used for regular monitoring of the TIRS absolute calibration. The buoy initial results showed a large error in both bands, 0.29 and 0.51 W/m2·sr·μm or −2.1 K and −4.4 K at 300 K in Band 10 and 11 respectively, where TIRS data was too hot. A calibration update was recommended for both bands to correct for a bias error and was implemented on 3 February 2014 in the USGS/EROS processing system, but the residual variability is still larger than desired for both bands (0.12 and 0.2 W/m2·sr·μm or 0.87 and 1.67 K at 300 K. Additional work has uncovered the source of the calibration error: out-of-field stray light. While analysis continues to characterize the stray light contribution, the vicarious calibration work proceeds. The additional data have not changed

  11. Calibration of Geodetic Instruments

    Directory of Open Access Journals (Sweden)

    Marek Bajtala

    2005-06-01

    Full Text Available The problem of metrology and security systems of unification, correctness and standard reproducibilities belong to the preferred requirements of theory and technical practice in geodesy. Requirements on the control and verification of measured instruments and equipments increase and the importance and up-to-date of calibration get into the foreground. Calibration possibilities of length-scales (of electronic rangefinders and angle-scales (of horizontal circles of geodetic instruments. Calibration of electronic rangefinders on the linear comparative baseline in terrain. Primary standard of planar angle – optical traverse and its exploitation for calibration of the horizontal circles of theodolites. The calibration equipment of the Institute of Slovak Metrology in Bratislava. The Calibration process and results from the calibration of horizontal circles of selected geodetic instruments.

  12. AFM lateral force calibration for an integrated probe using a calibration grating

    International Nuclear Information System (INIS)

    Wang, Huabin; Gee, Michelle L.

    2014-01-01

    Atomic force microscopy (AFM) friction measurements on hard and soft materials remain a challenge due to the difficulties associated with accurately calibrating the cantilever for lateral force measurement. One of the most widely accepted lateral force calibration methods is the wedge method. This method is often used in a simplified format but in so doing sacrifices accuracy. In the present work, we have further developed the wedge method to provide a lateral force calibration method for integrated AFM probes that is easy to use without compromising accuracy and reliability. Raw friction calibration data are collected from a single scan image by continuous ramping of the set point as the facets of a standard grating are scanned. These data are analysed to yield an accurate lateral force conversion/calibration factor that is not influenced by adhesion forces or load deviation. By demonstrating this new calibration method, we illustrate its reliability, speed and ease of execution. This method makes accessible reliable boundary lubrication studies on adhesive and heterogeneous surfaces that require spatial resolution of frictional forces. - Highlights: • We develop a simple and accurate method for lateral force calibration in AFM friction measurements. • We detail the basis of the method and illustrate how to use it and its reliability with example data. • Our method is easy, accurate and accounts for the affects of adhesion on friction measurements. • The method is applicable to integrated probes, as opposed to colloidal probes. • This allows accurate AFM friction measurements on spatially heterogeneous and adhesive surfaces

  13. Automated intraoperative calibration for prostate cancer brachytherapy

    International Nuclear Information System (INIS)

    Kuiran Chen, Thomas; Heffter, Tamas; Lasso, Andras; Pinter, Csaba; Abolmaesumi, Purang; Burdette, E. Clif; Fichtinger, Gabor

    2011-01-01

    Purpose: Prostate cancer brachytherapy relies on an accurate spatial registration between the implant needles and the TRUS image, called ''calibration''. The authors propose a new device and a fast, automatic method to calibrate the brachytherapy system in the operating room, with instant error feedback. Methods: A device was CAD-designed and precision-engineered, which mechanically couples a calibration phantom with an exact replica of the standard brachytherapy template. From real-time TRUS images acquired from the calibration device and processed by the calibration system, the coordinate transformation between the brachytherapy template and the TRUS images was computed automatically. The system instantly generated a report of the target reconstruction accuracy based on the current calibration outcome. Results: Four types of validation tests were conducted. First, 50 independent, real-time calibration trials yielded an average of 0.57 ± 0.13 mm line reconstruction error (LRE) relative to ground truth. Second, the averaged LRE was 0.37 ± 0.25 mm relative to ground truth in tests with six different commercial TRUS scanners operating at similar imaging settings. Furthermore, testing with five different commercial stepper systems yielded an average of 0.29 ± 0.16 mm LRE relative to ground truth. Finally, the system achieved an average of 0.56 ± 0.27 mm target registration error (TRE) relative to ground truth in needle insertion tests through the template in a water tank. Conclusions: The proposed automatic, intraoperative calibration system for prostate cancer brachytherapy has achieved high accuracy, precision, and robustness.

  14. Calibration Errors in Interferometric Radio Polarimetry

    Science.gov (United States)

    Hales, Christopher A.

    2017-08-01

    Residual calibration errors are difficult to predict in interferometric radio polarimetry because they depend on the observational calibration strategy employed, encompassing the Stokes vector of the calibrator and parallactic angle coverage. This work presents analytic derivations and simulations that enable examination of residual on-axis instrumental leakage and position-angle errors for a suite of calibration strategies. The focus is on arrays comprising alt-azimuth antennas with common feeds over which parallactic angle is approximately uniform. The results indicate that calibration schemes requiring parallactic angle coverage in the linear feed basis (e.g., the Atacama Large Millimeter/submillimeter Array) need only observe over 30°, beyond which no significant improvements in calibration accuracy are obtained. In the circular feed basis (e.g., the Very Large Array above 1 GHz), 30° is also appropriate when the Stokes vector of the leakage calibrator is known a priori, but this rises to 90° when the Stokes vector is unknown. These findings illustrate and quantify concepts that were previously obscure rules of thumb.

  15. Calibration of cosmogenic 3He and 10Be production rates in the High Tropics

    Science.gov (United States)

    Blard, Pierre-Henri; Martin, Léo; Lavé, Jérôme; Charreau, Julien; Condom, Thomas; Lupker, Maarten; Braucher, Régis; Bourlès, Didier

    2014-05-01

    It is critical to refine both the accuracy and the precision of the in situ cosmogenic dating tool, especially for establishing reliable glacial chronologies that can be compared to other paleoclimatic records. Recent cross-calibrations of cosmogenic 3He in pyroxene and 10Be in quartz [1, 2] showed that, both at low (1300 m) and high elevation (4850 m), the 3He/10Be production ratio was probably ~40% higher than the value of ~23 initially defined in the 90's. This recent update is consistent with the last independent determinations of the sea level high latitude production rates of 10Be and 3He, that are about 4 and 125 at.g-1.yr-1, respectively [e.g. 3, 4]. However, major questions remain about these production rates at high elevation, notably because existing calibration sites for both 3He and 10Be are scarce above 2000 m. It is thus crucial to produce new high precision calibration data at high elevation. Here we report cosmogenic 10Be data from boulders sampled on a glacial fan located at 3800 m in the Central Altiplano (Bolivia), whose age is independently constrained by stratigraphic correlations and radiocarbon dating at ca. 16 ka. These data can be used to calibrate the production rate of 10Be at high elevation, in the Tropics. After scaling to sea level and high latitude, these data yield a sea level high latitude P10 ranging from 3.8 to 4.2 at.g-1.yr-1, depending on the used scaling scheme. These new calibration data are in good agreement with recent absolute and cross-calibration of 3He in pyroxenes and 10Be in quartz, from dacitic moraines located at 4850 m in the Southern Altiplano (22° S, Tropical Andes) [2,5]. The so-obtained 3He/10Be production ratio of 33.3±0.9 (1σ) combined with an absolute 3He production rate locally calibrated in the Central Altiplano, at 3800 m, indeed yielded a sea level high latitude P10 ranging from 3.7±0.2 to 4.1±0.2 at.g-1.yr-1, depending on the scaling scheme [2,5]. These values are also consistent with the 10Be

  16. Cadastral Database Positional Accuracy Improvement

    Science.gov (United States)

    Hashim, N. M.; Omar, A. H.; Ramli, S. N. M.; Omar, K. M.; Din, N.

    2017-10-01

    Positional Accuracy Improvement (PAI) is the refining process of the geometry feature in a geospatial dataset to improve its actual position. This actual position relates to the absolute position in specific coordinate system and the relation to the neighborhood features. With the growth of spatial based technology especially Geographical Information System (GIS) and Global Navigation Satellite System (GNSS), the PAI campaign is inevitable especially to the legacy cadastral database. Integration of legacy dataset and higher accuracy dataset like GNSS observation is a potential solution for improving the legacy dataset. However, by merely integrating both datasets will lead to a distortion of the relative geometry. The improved dataset should be further treated to minimize inherent errors and fitting to the new accurate dataset. The main focus of this study is to describe a method of angular based Least Square Adjustment (LSA) for PAI process of legacy dataset. The existing high accuracy dataset known as National Digital Cadastral Database (NDCDB) is then used as bench mark to validate the results. It was found that the propose technique is highly possible for positional accuracy improvement of legacy spatial datasets.

  17. Proton beam monitor chamber calibration

    International Nuclear Information System (INIS)

    Gomà, C; Meer, D; Safai, S; Lorentini, S

    2014-01-01

    The first goal of this paper is to clarify the reference conditions for the reference dosimetry of clinical proton beams. A clear distinction is made between proton beam delivery systems which should be calibrated with a spread-out Bragg peak field and those that should be calibrated with a (pseudo-)monoenergetic proton beam. For the latter, this paper also compares two independent dosimetry techniques to calibrate the beam monitor chambers: absolute dosimetry (of the number of protons exiting the nozzle) with a Faraday cup and reference dosimetry (i.e. determination of the absorbed dose to water under IAEA TRS-398 reference conditions) with an ionization chamber. To compare the two techniques, Monte Carlo simulations were performed to convert dose-to-water to proton fluence. A good agreement was found between the Faraday cup technique and the reference dosimetry with a plane-parallel ionization chamber. The differences—of the order of 3%—were found to be within the uncertainty of the comparison. For cylindrical ionization chambers, however, the agreement was only possible when positioning the effective point of measurement of the chamber at the reference measurement depth—i.e. not complying with IAEA TRS-398 recommendations. In conclusion, for cylindrical ionization chambers, IAEA TRS-398 reference conditions for monoenergetic proton beams led to a systematic error in the determination of the absorbed dose to water, especially relevant for low-energy proton beams. To overcome this problem, the effective point of measurement of cylindrical ionization chambers should be taken into account when positioning the reference point of the chamber. Within the current IAEA TRS-398 recommendations, it seems advisable to use plane-parallel ionization chambers—rather than cylindrical chambers—for the reference dosimetry of pseudo-monoenergetic proton beams. (paper)

  18. Calibration of the Ørsted vector magnetometer

    DEFF Research Database (Denmark)

    Olsen, Nils; Tøffner-Clausen, Lars; Sabaka, T.J.

    2003-01-01

    The vector fluxgate magnetometer of the Orsted satellite is routinely calibrated by comparing its output with measurements of the absolute magnetic intensity from the Overhauser instrument, which is the second magnetometer of the satellite. We describe the method used for and the result obtained...

  19. Planck 2013 results. VIII. HFI photometric calibration and mapmaking

    CERN Document Server

    Ade, P A R; Armitage-Caplan, C; Arnaud, M; Ashdown, M; Atrio-Barandela, F; Aumont, J; Baccigalupi, C; Banday, A J; Barreiro, R B; Battaner, E; Benabed, K; Benoît, A; Benoit-Lévy, A; Bernard, J -P; Bersanelli, M; Bertincourt, B; Bielewicz, P; Bobin, J; Bock, J J; Bond, J R; Borrill, J; Bouchet, F R; Boulanger, F; Bridges, M; Bucher, M; Burigana, C; Cardoso, J -F; Catalano, A; Challinor, A; Chamballu, A; Chary, R -R; Chen, X; Chiang, L -Y; Chiang, H C; Christensen, P R; Church, S; Clements, D L; Colombi, S; Colombo, L P L; Combet, C; Couchot, F; Coulais, A; Crill, B P; Curto, A; Cuttaia, F; Danese, L; Davies, R D; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Désert, F -X; Dickinson, C; Diego, J M; Dole, H; Donzelli, S; Doré, O; Douspis, M; Dupac, X; Efstathiou, G; Enßlin, T A; Eriksen, H K; Filliard, C; Finelli, F; Forni, O; Frailis, M; Franceschi, E; Galeotta, S; Ganga, K; Giard, M; Giardino, G; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Gruppuso, A; Hansen, F K; Hanson, D; Harrison, D; Helou, G; Henrot-Versillé, S; Hernández-Monteagudo, C; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hornstrup, A; Hovest, W; Huffenberger, K M; Jaffe, T R; Jaffe, A H; Jones, W C; Juvela, M; Keihänen, E; Keskitalo, R; Kisner, T S; Kneissl, R; Knoche, J; Knox, L; Kunz, M; Kurki-Suonio, H; Lagache, G; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lawrence, C R; Jeune, M Le; Lellouch, E; Leonardi, R; Leroy, C; Lesgourgues, J; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maffei, B; Mandolesi, N; Maris, M; Marshall, D J; Martin, P G; Martínez-González, E; Masi, S; Matarrese, S; Matthai, F; Maurin, L; Mazzotta, P; McGehee, P; Meinhold, P R; Melchiorri, A; Mendes, L; Mennella, A; Migliaccio, M; Mitra, S; Miville-Deschênes, M -A; Moneti, A; Montier, L; Moreno, R; Morgante, G; Mortlock, D; Munshi, D; Murphy, J A; Naselsky, P; Nati, F; Natoli, P; Netterfield, C B; Nørgaard-Nielsen, H U; Noviello, F; Novikov, D; Novikov, I; Osborne, S; Oxborrow, C A; Paci, F; Pagano, L; Pajot, F; Paladini, R; Paoletti, D; Partridge, B; Pasian, F; Patanchon, G; Perdereau, O; Perotto, L; Perrotta, F; Piacentini, F; Piat, M; Pierpaoli, E; Pietrobon, D; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Popa, L; Poutanen, T; Pratt, G W; Prézeau, G; Prunet, S; Puget, J -L; Rachen, J P; Reinecke, M; Remazeilles, M; Renault, C; Ricciardi, S; Riller, T; Ristorcelli, I; Rocha, G; Rosset, C; Roudier, G; Rusholme, B; Santos, D; Savini, G; Shellard, E P S; Spencer, L D; Starck, J -L; Stolyarov, V; Stompor, R; Sudiwala, R; Sunyaev, R; Sureau, F; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Tavagnacco, D; Techene, S; Terenzi, L; Tomasi, M; Tristram, M; Tucci, M; Umana, G; Valenziano, L; Valiviita, J; Van Tent, B; Vielva, P; Villa, F; Vittorio, N; Wade, L A; Wandelt, B D; Yvon, D; Zacchei, A; Zonca, A

    2014-01-01

    This paper describes the processing applied to the HFI cleaned time-ordered data to produce photometrically calibrated maps. HFI observes the sky over a broad range of frequencies, from 100 to 857 GHz. To get the best accuracy on the calibration on such a large range, two different photometric calibration schemes have to be used. The 545 and 857 \\GHz\\ data are calibrated using Uranus and Neptune flux density measurements, compared with models of their atmospheric emissions to calibrate the data. The lower frequencies (below 353 GHz) are calibrated using the cosmological microwave background dipole.One of the components of this anisotropy results from the orbital motion of the satellite in the Solar System, and is therefore time-variable. Photometric calibration is thus tightly linked to mapmaking, which also addresses low frequency noise removal. The 2013 released HFI data show some evidence for apparent gain variations of the HFI bolometers' detection chain. These variations were identified by comparing obse...

  20. A Comparison of Two Balance Calibration Model Building Methods

    Science.gov (United States)

    DeLoach, Richard; Ulbrich, Norbert

    2007-01-01

    Simulated strain-gage balance calibration data is used to compare the accuracy of two balance calibration model building methods for different noise environments and calibration experiment designs. The first building method obtains a math model for the analysis of balance calibration data after applying a candidate math model search algorithm to the calibration data set. The second building method uses stepwise regression analysis in order to construct a model for the analysis. Four balance calibration data sets were simulated in order to compare the accuracy of the two math model building methods. The simulated data sets were prepared using the traditional One Factor At a Time (OFAT) technique and the Modern Design of Experiments (MDOE) approach. Random and systematic errors were introduced in the simulated calibration data sets in order to study their influence on the math model building methods. Residuals of the fitted calibration responses and other statistical metrics were compared in order to evaluate the calibration models developed with different combinations of noise environment, experiment design, and model building method. Overall, predicted math models and residuals of both math model building methods show very good agreement. Significant differences in model quality were attributable to noise environment, experiment design, and their interaction. Generally, the addition of systematic error significantly degraded the quality of calibration models developed from OFAT data by either method, but MDOE experiment designs were more robust with respect to the introduction of a systematic component of the unexplained variance.

  1. A global algorithm for estimating Absolute Salinity

    Directory of Open Access Journals (Sweden)

    T. J. McDougall

    2012-12-01

    Full Text Available The International Thermodynamic Equation of Seawater – 2010 has defined the thermodynamic properties of seawater in terms of a new salinity variable, Absolute Salinity, which takes into account the spatial variation of the composition of seawater. Absolute Salinity more accurately reflects the effects of the dissolved material in seawater on the thermodynamic properties (particularly density than does Practical Salinity.

    When a seawater sample has standard composition (i.e. the ratios of the constituents of sea salt are the same as those of surface water of the North Atlantic, Practical Salinity can be used to accurately evaluate the thermodynamic properties of seawater. When seawater is not of standard composition, Practical Salinity alone is not sufficient and the Absolute Salinity Anomaly needs to be estimated; this anomaly is as large as 0.025 g kg−1 in the northernmost North Pacific. Here we provide an algorithm for estimating Absolute Salinity Anomaly for any location (x, y, p in the world ocean.

    To develop this algorithm, we used the Absolute Salinity Anomaly that is found by comparing the density calculated from Practical Salinity to the density measured in the laboratory. These estimates of Absolute Salinity Anomaly however are limited to the number of available observations (namely 811. In order to provide a practical method that can be used at any location in the world ocean, we take advantage of approximate relationships between Absolute Salinity Anomaly and silicate concentrations (which are available globally.

  2. Comparison of Different Calibration Methods in a Non-invasive ICP Assessment Model.

    Science.gov (United States)

    Schmidt, Bernhard; Cardim, Danilo; Weinhold, Marco; Streif, Stefan; McLeod, Damian D; Czosnyka, Marek; Klingelhöfer, Jürgen

    2018-01-01

    Previously we described the method of continuous intracranial pressure (ICP) estimation using arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV). The model was constructed using reference patient data. Various individual calibration strategies were used in the current attempt to improve the accuracy of this non-invasive ICP (nICP) assessment tool. Forty-one patients (mean, 52 years; range, 18-77 years) with severe brain injuries were studied. CBFV in the middle cerebral artery (MCA), ABP and invasively assessed ICP were simultaneously recorded for 1 h. Recording was repeated at days 2, 4 and 7. In the first recording, invasively assessed ICP was recorded to calibrate the nICP procedure by means of either a constant shift of nICP (snICP), a constant shift of nICP/ABP ratio (anICP) or by including this recording for a model reconstruction (cnICP). At follow-up days, the calibrated nICP procedures were applied and the results compared to the original nICP. In 76 follow-up recordings, the mean differences (Bias), the SD and the mean absolute differences (ΔICP) between ICP and the nICP methods were (in mmHg): nICP, -5.6 ± 5.72, 6.5; snICP, +0.7 ± 6.98, 5.5, n.s.; anICP, +1.0 ± 7.22, 5.6, n.s.; cnICP, -3.4 ± 5.68, 5.4, p ICP. This overestimation could be reduced by cnICP calibration, but not completely avoided. Constant shift calibrations (snICP, anICP) decrease the Bias to ICP, but increase SD and, therefore, increase the 95% confidence interval (CI = 2 × SD). This calibration method cannot be recommended. Compared to nICP, the cnICP method reduced the Bias and slightly reduced SD, and showed significantly decreased ΔICP. Compared to snICP and anICP, the Bias was higher. This effect was probably caused by the patients with craniotomy. The cnICP calibration method using initial recordings for model reconstruction showed the best results.

  3. Estimating Absolute and Relative Physical Activity Intensity Across Age via Accelerometry in Adults

    OpenAIRE

    Miller, Nora E.; Strath, Scott J.; Swartz, Ann M.; Cashin, Susan E.

    2010-01-01

    This study examined the predictive validity of accelerometers (ACC) to estimate physical activity intensity (PAI) across age and differences in intensity predictions when expressed in relative and absolute PAI terms. Ninety adults categorized into 3 age groups (20–29, 40–49, and 60–69 yr) completed a treadmill calibration study with simultaneous ACC (7164 Actigraph) and oxygen-consumption assessment. Results revealed strong linear relations between ACC output and measured PAI (R2 = .62–.89) a...

  4. Accuracy Analysis and Validation of the Mars Science Laboratory (MSL) Robotic Arm

    Science.gov (United States)

    Collins, Curtis L.; Robinson, Matthew L.

    2013-01-01

    The Mars Science Laboratory (MSL) Curiosity Rover is currently exploring the surface of Mars with a suite of tools and instruments mounted to the end of a five degree-of-freedom robotic arm. To verify and meet a set of end-to-end system level accuracy requirements, a detailed positioning uncertainty model of the arm was developed and exercised over the arm operational workspace. Error sources at each link in the arm kinematic chain were estimated and their effects propagated to the tool frames.A rigorous test and measurement program was developed and implemented to collect data to characterize and calibrate the kinematic and stiffness parameters of the arm. Numerous absolute and relative accuracy and repeatability requirements were validated with a combination of analysis and test data extrapolated to the Mars gravity and thermal environment. Initial results of arm accuracy and repeatability on Mars demonstrate the effectiveness of the modeling and test program as the rover continues to explore the foothills of Mount Sharp.

  5. On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform

    Science.gov (United States)

    Brown, Anthony M.

    2018-01-01

    Recent advances in unmanned aerial vehicle (UAV) technology have made UAVs an attractive possibility as an airborne calibration platform for astronomical facilities. This is especially true for arrays of telescopes spread over a large area such as the Cherenkov Telescope Array (CTA). In this paper, the feasibility of using UAVs to calibrate CTA is investigated. Assuming a UAV at 1km altitude above CTA, operating on astronomically clear nights with stratified, low atmospheric dust content, appropriate thermal protection for the calibration light source and an onboard photodiode to monitor its absolute light intensity, inter-calibration of CTA's telescopes of the same size class is found to be achievable with a 6 - 8 % uncertainty. For cross-calibration of different telescope size classes, a systematic uncertainty of 8 - 10 % is found to be achievable. Importantly, equipping the UAV with a multi-wavelength calibration light source affords us the ability to monitor the wavelength-dependent degradation of CTA telescopes' optical system, allowing us to not only maintain this 6 - 10 % uncertainty after the first few years of telescope deployment, but also to accurately account for the effect of multi-wavelength degradation on the cross-calibration of CTA by other techniques, namely with images of air showers and local muons. A UAV-based system thus provides CTA with several independent and complementary methods of cross-calibrating the optical throughput of individual telescopes. Furthermore, housing environmental sensors on the UAV system allows us to not only minimise the systematic uncertainty associated with the atmospheric transmission of the calibration signal, it also allows us to map the dust content above CTA as well as monitor the temperature, humidity and pressure profiles of the first kilometre of atmosphere above CTA with each UAV flight.

  6. Absolute Thermal SST Measurements over the Deepwater Horizon Oil Spill

    Science.gov (United States)

    Good, W. S.; Warden, R.; Kaptchen, P. F.; Finch, T.; Emery, W. J.

    2010-12-01

    Climate monitoring and natural disaster rapid assessment require baseline measurements that can be tracked over time to distinguish anthropogenic versus natural changes to the Earth system. Disasters like the Deepwater Horizon Oil Spill require constant monitoring to assess the potential environmental and economic impacts. Absolute calibration and validation of Earth-observing sensors is needed to allow for comparison of temporally separated data sets and provide accurate information to policy makers. The Ball Experimental Sea Surface Temperature (BESST) radiometer was designed and built by Ball Aerospace to provide a well calibrated measure of sea surface temperature (SST) from an unmanned aerial system (UAS). Currently, emissive skin SST observed by satellite infrared radiometers is validated by shipborne instruments that are expensive to deploy and can only take a few data samples along the ship track to overlap within a single satellite pixel. Implementation on a UAS will allow BESST to map the full footprint of a satellite pixel and perform averaging to remove any local variability due to the difference in footprint size of the instruments. It also enables the capability to study this sub-pixel variability to determine if smaller scale effects need to be accounted for in models to improve forecasting of ocean events. In addition to satellite sensor validation, BESST can distinguish meter scale variations in SST which could be used to remotely monitor and assess thermal pollution in rivers and coastal areas as well as study diurnal and seasonal changes to bodies of water that impact the ocean ecosystem. BESST was recently deployed on a conventional Twin Otter airplane for measurements over the Gulf of Mexico to access the thermal properties of the ocean surface being affected by the oil spill. Results of these measurements will be presented along with ancillary sensor data used to eliminate false signals including UV and Synthetic Aperture Radar (SAR

  7. Jasminum flexile flower absolute from India--a detailed comparison with three other jasmine absolutes.

    Science.gov (United States)

    Braun, Norbert A; Kohlenberg, Birgit; Sim, Sherina; Meier, Manfred; Hammerschmidt, Franz-Josef

    2009-09-01

    Jasminum flexile flower absolute from the south of India and the corresponding vacuum headspace (VHS) sample of the absolute were analyzed using GC and GC-MS. Three other commercially available Indian jasmine absolutes from the species: J. sambac, J. officinale subsp. grandiflorum, and J. auriculatum and the respective VHS samples were used for comparison purposes. One hundred and twenty-one compounds were characterized in J. flexile flower absolute, with methyl linolate, benzyl salicylate, benzyl benzoate, (2E,6E)-farnesol, and benzyl acetate as the main constituents. A detailed olfactory evaluation was also performed.

  8. Radiometric calibration of the in-flight blackbody calibration system of the GLORIA interferometer

    Directory of Open Access Journals (Sweden)

    C. Monte

    2014-01-01

    Atmosphere is an airborne, imaging, infrared Fourier transform spectrometer that applies the limb-imaging technique to perform trace gas and temperature measurements in the Earth's atmosphere with three-dimensional resolution. To ensure the traceability of these measurements to the International Temperature Scale and thereby to an absolute radiance scale, GLORIA carries an on-board calibration system. Basically, it consists of two identical large-area and high-emissivity infrared radiators, which can be continuously and independently operated at two adjustable temperatures in a range from −50 °C to 0 °C during flight. Here we describe the radiometric and thermometric characterization and calibration of the in-flight calibration system at the Reduced Background Calibration Facility of the Physikalisch-Technische Bundesanstalt. This was performed with a standard uncertainty of less than 110 mK. Extensive investigations of the system concerning its absolute radiation temperature and spectral radiance, its temperature homogeneity and its short- and long-term stability are discussed. The traceability chain of these measurements is presented.

  9. Simultaneous calibration phantom commission and geometry calibration in cone beam CT.

    Science.gov (United States)

    Xu, Yuan; Yang, Shuai; Ma, Jianhui; Li, Bin; Wu, Shuyu; Qi, Hongliang; Zhou, Linghong

    2017-08-09

    Geometry calibration is a vital step for describing the geometry of a cone beam computed tomography (CBCT) system and is a prerequisite for CBCT reconstruction. In current methods, calibration phantom commission and geometry calibration are divided into two independent tasks. Small errors in ball-bearing (BB) positioning in the phantom-making step will severely degrade the quality of phantom calibration. To solve this problem, we propose an integrated method to simultaneously realize geometry phantom commission and geometry calibration. Instead of assuming the accuracy of the geometry phantom, the integrated method considers BB centers in the phantom as an optimized parameter in the workflow. Specifically, an evaluation phantom and the corresponding evaluation contrast index are used to evaluate geometry artifacts for optimizing the BB coordinates in the geometry phantom. After utilizing particle swarm optimization, the CBCT geometry and BB coordinates in the geometry phantom are calibrated accurately and are then directly used for the next geometry calibration task in other CBCT systems. To evaluate the proposed method, both qualitative and quantitative studies were performed on simulated and realistic CBCT data. The spatial resolution of reconstructed images using dental CBCT can reach up to 15 line pair cm -1 . The proposed method is also superior to the Wiesent method in experiments. This paper shows that the proposed method is attractive for simultaneous and accurate geometry phantom commission and geometry calibration.

  10. Calibration platforms for gravimeters

    Science.gov (United States)

    Vanruymbeke, M.

    Several methods investigated in order to calibrate gravimeters by the inertial acceleration produced by a vertical motion are described. The VRR 8601 calibrating platform is especially designed to calibrate La Coste and Romberg gravimeters. For heavier gravimeters such as tidal La Coste or superconducting instruments, two other principles are possible to lift up sinusoidally the platform: a mercury crapaudine or the rotation on an inclined plane.

  11. Development of a high-performance spectral radiometer for EO calibration applications

    Science.gov (United States)

    Matis, Gregory; Bryant, Paul; James, Jay B.; McHugh, Steve

    2004-08-01

    Santa Barbara Infrared, Inc (SBIR) has developed a dual-band infrared spectroradiometer for highly accurate radiometric calibration of electro-optical (EO) test stations, light sources, and optical surfaces. The "RAD-9000" design covers the 3-5 mm and 8-12 mm spectral bands, provides thermal sensitivity of better than 40 mK, supports object temperatures from 278-373 K, and delivers better than 2% spectral resolution (Dl/l). The RAD-9000 features computer-controlled operation, an intuitive graphical user interface (GUI), motorized focus adjustment, VIS-CCD sighting/alignment capability, less than 2 mrad detector IFOV, and an internal ambient reference for background subtraction and enhanced stability. In addition to high-performance relative radiometry, the RAD-9000 offers a high degree of absolute radiometric accuracy by utilizing a dedicated radiometric reference module. The reference module incorporates two 8-inch, variable temperature, high-emissivity extended sources to provide a stable, accurate absolute radiometric reference external to the main optics.

  12. Calibrating nacelle lidars

    DEFF Research Database (Denmark)

    Courtney, Michael

    presents four concepts for performing such a nacelle lidar calibration. Of the four methods, two are found to be immediately relevant and are pursued in some detail. The first of these is a line of sight calibration method in which both lines of sight (for a two beam lidar) are individually calibrated...... by accurately aligning the beam to pass close to a reference wind speed sensor. A testing procedure is presented, reporting requirements outlined and the uncertainty of the method analysed. It is seen that the main limitation of the line of sight calibration method is the time required to obtain...

  13. ATLAS Muon Calibration Frameowrk

    CERN Document Server

    Carlino, Dr; The ATLAS collaboration; Jha, Dr; Kortner, Dr; Mazzaferro, Dr; Petrucci, Dr; Salvo, Dr; Simone, Dr; WALKER, Dr

    2010-01-01

    Automated calibration of the ATLAS detector subsystems ( like MDT and RPC chambers) are being performed at remote sites, called Remote Calibration Centers. The calibration data for the assigned part of the detector are being processed at these centers and send the result back to CERN for general use in reconstruction and analysis. In this work, we present the recent developments in data discovery mechanism and integration of Ganga as a backend which allows for the specification, submission, bookkeeping and post processing of calibration tasks on a wide set of available heterogeneous resources at remote centers.

  14. ATLAS Muon Calibration Framework

    CERN Document Server

    CARLINO, G; The ATLAS collaboration; Di Simone, A; Doria, A; Jha, MK; Mazzaferro, L; Walker, R

    2011-01-01

    Automated calibration of the ATLAS detector subsystems ( like MDT and RPC chambers) are being performed at remote sites, called Remote Calibration Centers. The calibration data for the assigned part of the detector are being processed at these centers and send the result back to CERN for general use in reconstruction and analysis. In this work, we present the recent developments in data discovery mechanism and integration of Ganga as a backend which allows for the specification, submission, bookkeeping and post processing of calibration tasks on a wide set of available heterogeneous resources at remote centers.

  15. RF impedance measurement calibration

    International Nuclear Information System (INIS)

    Matthews, P.J.; Song, J.J.

    1993-01-01

    The intent of this note is not to explain all of the available calibration methods in detail. Instead, we will focus on the calibration methods of interest for RF impedance coupling measurements and attempt to explain: (1). The standards and measurements necessary for the various calibration techniques. (2). The advantages and disadvantages of each technique. (3). The mathematical manipulations that need to be applied to the measured standards and devices. (4). An outline of the steps needed for writing a calibration routine that operated from a remote computer. For further details of the various techniques presented in this note, the reader should consult the references

  16. Analysis of absolute flatness testing in sub-stitching interferometer

    Science.gov (United States)

    Jia, Xin; Xu, Fuchao; Xie, Weimin; Xing, Tingwen

    2016-09-01

    Sub-aperture stitching is an effective way to extend the lateral and vertical dynamic range of a conventional interferometer. The test accuracy can be achieved by removing the error of reference surface by the absolute testing method. When the testing accuracy (repeatability and reproducibility) is close to 1nm, in addition to the reference surface, other factors will also affect the measuring accuracy such as environment, zoom magnification, stitching precision, tooling and fixture, the characteristics of optical materials and so on. In the thousand level cleanroom, we establish a good environment system. Long time stability, temperature controlled at 22°+/-0.02°.The humidity and noise are controlled in a certain range. We establish a stitching system in the clean room. The vibration testing system is used to test the vibration. The air pressure testing system is also used. In the motion system, we control the tilt error no more than 4 second to reduce the error. The angle error can be tested by the autocollimator and double grating reading head.

  17. Simultaneous overpass off nadir (SOON): a method for unified calibration/validation across IEOS and GEOSS system of systems

    Science.gov (United States)

    Ardanuy, Philip; Bergen, Bill; Huang, Allen; Kratz, Gene; Puschell, Jeff; Schueler, Carl; Walker, Joe

    2006-08-01

    The US operates a diverse, evolving constellation of research and operational environmental satellites, principally in polar and geosynchronous orbits. Our current and enhanced future domestic remote sensing capability is complemented by the significant capabilities of our current and potential future international partners. In this analysis, we define "success" through the data customers' "eyes": participating in the sufficient and continuously improving satisfaction of their mission responsibilities. To successfully fuse together observations from multiple simultaneous platforms and sensors into a common, self-consistent, operational environment requires that there exist a unified calibration and validation approach. Here, we consider develop a concept for an integrating framework for absolute accuracy; long-term stability; self-consistency among sensors, platforms, techniques, and observing systems; and validation and characterization of performance. Across all systems, this is a non-trivial problem. Simultaneous Nadir Overpasses, or SNO's, provide a proven intercomparison technique: simultaneous, collocated, co-angular measurements. Many systems have off-nadir elements, or effects, that must be calibrated. For these systems, the nadir technique constrains the process. We define the term "SOON," for simultaneous overpass off nadir. We present a target architecture and sensitivity analysis for the affordable, sustainable implementation of a global SOON calibration/validation network that can deliver the much-needed comprehensive, common, self-consistent operational picture in near-real time, at an affordable cost.

  18. A 20-40 MHz low-power clock oscillator with open-loop frequency calibration and temperature compensation

    Science.gov (United States)

    Lee, Dongsoo; Kim, Hongjin; Lee, Kang-Yoon

    2014-05-01

    In this paper, a 20-40 MHz low-power clock oscillator is presented to provide the frequency reference in data interface applications. The frequency source is referenced to a frequency-calibrated and temperature-compensated 2.5 GHz LC VCO that is implemented with a bondwire inductor. Class-C type VCO is adopted in order to improve the phase noise and reduce the current consumption. A full digital frequency calibration circuit is proposed to cover the wide output frequency range minimizing the frequency variation. External crystal oscillator (REF_CLK) is used only for the absolute frequency calibration at the initial programming stage and is not needed after the programming stage. On the other hand, temperature compensation is performed in an analogue way by controlling the varactor in the LC VCO. This chip is fabricated using 0.18-µm CMOS with the option of lateral PNP transistor. Lateral PNP transistors are used in the temperature compensation circuits. It can be implemented laterally in standard CMOS process. The power consumption is 4.8 mW from a 1.8 V supply. The accuracy of the frequency is ±58 ppm from -20°C to 80°C. The nominal phase noise at 1 MHz and period jitter is -122 dBc/Hz and 2 ps, respectively, when the output frequency is 25 MHz.

  19. Accuracy of the pressure scale of sphygmomanometers in clinical use within primary care.

    Science.gov (United States)

    Coleman, Andrew J; Steel, Stephen D; Ashworth, Mark; Vowler, Sarah L; Shennan, Andrew

    2005-08-01

    It is widely recommended that sphygmomanometers are maintained and calibrated regularly to ensure that the pressure scale remains accurate to within the European Standard specification of +/-3 mmHg. In primary care, however, such checks are reported to be only rarely performed. This paper describes a survey of the accuracy of the absolute static pressure scale of aneroid, mercury and automated sphygmomanometers in clinical use in primary care. On-site measurements of sphygmomanometer pressure scale accuracy were carried out in 45 general practices within Lambeth, Southwark and Lewisham. A total of 279 sphygmomanometers from these practices were included in the study. The device pressure scales were calibrated using an accurate electronic reference pressure sensor. The key finding of this study is that 17.9% (50 out of 279) of all surveyed devices gave errors exceeding the +/-3 mmHg threshold. Of these, 53.2% (33 out of 62) of aneroid devices were found to be reading in error by more than +/-3 mmHg compared with 7.8% (16 out of 217) of the combined population of mercury and automated devices. The difference between these groups is statistically significant (P=0.002). Significant differences in the performance of specific models of aneroid, mercury and automated devices were also identified. A service model for improving the accuracy of blood pressure monitoring in primary care needs to take into account the current proliferation of pressure scale errors in these devices, the lack of uptake of regular checks and the poor quality of some of the devices currently in use.

  20. Distance measurement using frequency-modulated continuous-wave ladar with calibration by a femtosecond frequency comb

    Science.gov (United States)

    Liu, Yang; Yang, Linghui; Lin, Jiarui; Zhu, Jigui

    2018-01-01

    Precise distance measurement is of interest for large-scale manufacturing, future space satellite missions, and other industrial applications. The ranging system with femtosecond optical frequency comb (FOFC) could offer high accuracy, stability and direct traceability to SI definition of the meter. Here, we propose a scheme for length measurement based on the frequency-modulated continuous-wave (FMCW) ladar with a FOFC. In this scheme, the reference interferometer in the FMCW ladar is calibrated by the intensity detection using the FOFC in the time domain within an optical wavelength resolution. With analysis of the theoretical model, this system has the potential to a high-speed, high-accuracy absolute distance measurement. Then, based on the experimental results, the evaluation of the performance of the calibration of the reference arm is discussed. In addition, the performance of this system is evaluated by a single position measurement with different tuning velocities of wavelength. The experimental results show that the reproducibility of the distance measurement is 10-5 level.

  1. Data multiplexing in radio interferometric calibration

    Science.gov (United States)

    Yatawatta, Sarod; Diblen, Faruk; Spreeuw, Hanno; Koopmans, L. V. E.

    2018-03-01

    New and upcoming radio interferometers will produce unprecedented amount of data that demand extremely powerful computers for processing. This is a limiting factor due to the large computational power and energy costs involved. Such limitations restrict several key data processing steps in radio interferometry. One such step is calibration where systematic errors in the data are determined and corrected. Accurate calibration is an essential component in reaching many scientific goals in radio astronomy and the use of consensus optimization that exploits the continuity of systematic errors across frequency significantly improves calibration accuracy. In order to reach full consensus, data at all frequencies need to be calibrated simultaneously. In the SKA regime, this can become intractable if the available compute agents do not have the resources to process data from all frequency channels simultaneously. In this paper, we propose a multiplexing scheme that is based on the alternating direction method of multipliers with cyclic updates. With this scheme, it is possible to simultaneously calibrate the full data set using far fewer compute agents than the number of frequencies at which data are available. We give simulation results to show the feasibility of the proposed multiplexing scheme in simultaneously calibrating a full data set when a limited number of compute agents are available.

  2. Using LabVIEW to facilitate calibration and verification for respiratory impedance plethysmography.

    Science.gov (United States)

    Ellis, W S; Jones, R T

    1991-12-01

    A system for calibrating the Respitrace impedance plethysmograph was developed with the capacity to quantitatively verify the accuracy of calibration. LabVIEW software was used on a Macintosh II computer to create a user-friendly environment, with the added benefit of reducing development time. The system developed enabled a research assistant to calibrate the Respitrace within 15 min while achieving an accuracy within the normally accepted 10% deviation when the Respitrace output is compared to a water spirometer standard. The system and methods described were successfully used in a study of 10 subjects smoking cigarettes containing marijuana or cocaine under four conditions, calibrating all subjects to 10% accuracy within 15 min.

  3. A new irradiated quartz for beta source calibration

    DEFF Research Database (Denmark)

    Hansen, Vicki; Murray, Andrew Sean; Buylaert, Jan-Pieter

    2015-01-01

    For luminescence dating to be an accurate absolute dating technique it is very important that we are able to deliver absolutely known radiation doses in the laboratory. This is normally done using a radiation source (alpha, beta, X-ray) calibrated against an absolutely known reference source. Man...... doses from a standardised gamma source to in-built irradiation sources....... from south-western Denmark (Rømø). Two grain sizes (4-11μm and 180-250μm) have been examined in detail. These were pre-treated (annealed, dosed and annealed again) to sensitise and stabilise the luminescence signals before being given an absolutely known gamma dose from a point 137Cs source in scatter...

  4. Effects of line fiducial parameters and beamforming on ultrasound calibration.

    Science.gov (United States)

    Ameri, Golafsoun; Baxter, John S H; McLeod, A Jonathan; Peters, Terry M; Chen, Elvis C S

    2017-01-01

    Ultrasound (US)-guided interventions are often enhanced via integration with an augmented reality environment, a necessary component of which is US calibration. Calibration requires the segmentation of fiducials, i.e., a phantom, in US images. Fiducial localization error (FLE) can decrease US calibration accuracy, which fundamentally affects the total accuracy of the interventional guidance system. Here, we investigate the effects of US image reconstruction techniques as well as phantom material and geometry on US calibration. It was shown that the FLE was reduced by 29% with synthetic transmit aperture imaging compared with conventional B-mode imaging in a Z-bar calibration, resulting in a 10% reduction of calibration error. In addition, an evaluation of a variety of calibration phantoms with different geometrical and material properties was performed. The phantoms included braided wire, plastic straws, and polyvinyl alcohol cryogel tubes with different diameters. It was shown that these properties have a significant effect on calibration error, which is a variable based on US beamforming techniques. These results would have important implications for calibration procedures and their feasibility in the context of image-guided procedures.

  5. Radiometric Cross-Calibration of the Chilean Satellite FASat-C Using RapidEye and EO-1 Hyperion Data and a Simultaneous Nadir Overpass Approach

    Directory of Open Access Journals (Sweden)

    Carolina Barrientos

    2016-07-01

    Full Text Available The absolute radiometric calibration of a satellite sensor is the critical factor that ensures the usefulness of the acquired data for quantitative applications on remote sensing. This work presents the results of the first cross-calibration of the sensor on board the Sistema Satelital de Observación de la Tierra (SSOT Chilean satellite or Air Force Satellite FASat-C. RapidEye-MSI was chosen as the reference sensor, and a simultaneous Nadir Overpass Approach (SNO was applied. The biases caused by differences in the spectral responses of both instruments were compensated through an adjustment factor derived from EO-1 Hyperion data. Through this method, the variations affecting the radiometric response of New AstroSat Optical Modular Instrument (NAOMI-1, have been corrected based on collections over the Frenchman Flat calibration site. The results of a preliminary evaluation of the pre-flight and updated coefficients have shown a significant improvement in the accuracy of at-sensor radiances and TOA reflectances: an average agreement of 2.63% (RMSE was achieved for the multispectral bands of both instruments. This research will provide a basis for the continuity of calibration and validation tasks of future Chilean space missions.

  6. Calibration of an x-ray cabinet unit for radiobiology use

    International Nuclear Information System (INIS)

    McKerracher, Carolyn; Thwaites, David I

    2006-01-01

    A Faxitron sealed x-ray cabinet, operated at 100 kV, was modified to irradiate monkey testicles, to a uniform, accurately calibrated dose, for work aimed at investigating spermatogenesis in children undergoing radiotherapy. An aluminium filter was added to increase the beam quality and a lead collimating system manufactured to reduce the beam size to between 1 and 4 cm diameter. Percentage depth doses and profiles were analysed and relative in-air outputs measured with a selection of small (0.2 cc, 0.015 cc) ion chambers. The absolute calibration of the unit was carried out in a 10 x 10 cm 2 beam with a 0.6 cc chamber. Backscatter factors were based on standard tables, but then modified according to experimental results with thermoluminescent dosimeters (TLD) in a phantom to account for reduced scatter in the irradiation situations. A suitable irradiation set-up was devised for the monkeys, to ensure accuracy of delivered dose to the target volume and minimize the dose to the surrounding healthy tissue. The homogeneity throughout the testes was calculated to be well within ±5%, using a parallel-opposed irradiation technique. The TLD measured doses to the testes on three monkeys were lower than the calculated doses by 3 to 6%. Following modifications to the standard percentage depth doses to account for changes in scatter conditions, these differences became ±3%. The uncertainties on both calculated and measured dose were estimated to be approximately ±3.2% at 1 SD

  7. Observer variability of absolute and relative thrombus density measurements in patients with acute ischemic stroke

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Emilie M.M. [Erasmus MC - University Medical Center Rotterdam, Department of Radiology, P.O. Box 2040, Rotterdam (Netherlands); Department of Radiology, AMC, Amsterdam (Netherlands); Yoo, Albert J. [Texas Stroke Institute, Plano, TX (United States); Beenen, Ludo F.; Majoie, Charles B. [Department of Radiology, AMC, Amsterdam (Netherlands); Berkhemer, Olvert A. [Department of Radiology, AMC, Amsterdam (Netherlands); Department of Neurology, Erasmus MC, Rotterdam (Netherlands); Blanken, Mark D. den; Wismans, Carrie [AMC, Department of Biomedical Engineering and Physics, Amsterdam (Netherlands); Niessen, Wiro J. [Erasmus MC - University Medical Center Rotterdam, Department of Radiology, P.O. Box 2040, Rotterdam (Netherlands); Delft University of Technology, Faculty of Applied Sciences, Delft (Netherlands); Marquering, Henk A. [Department of Radiology, AMC, Amsterdam (Netherlands); AMC, Department of Biomedical Engineering and Physics, Amsterdam (Netherlands); Collaboration: on behalf of the MR CLEAN investigators

    2016-02-15

    Thrombus density may be a predictor for acute ischemic stroke treatment success. However, only limited data on observer variability for thrombus density measurements exist. This study assesses the variability and bias of four common thrombus density measurement methods by expert and non-expert observers. For 132 consecutive patients with acute ischemic stroke, three experts and two trained observers determined thrombus density by placing three standardized regions of interest (ROIs) in the thrombus and corresponding contralateral arterial segment. Subsequently, absolute and relative thrombus densities were determined using either one or three ROIs. Intraclass correlation coefficient (ICC) was determined, and Bland-Altman analysis was performed to evaluate interobserver and intermethod agreement. Accuracy of the trained observer was evaluated with a reference expert observer using the same statistical analysis. The highest interobserver agreement was obtained for absolute thrombus measurements using three ROIs (ICCs ranging from 0.54 to 0.91). In general, interobserver agreement was lower for relative measurements, and for using one instead of three ROIs. Interobserver agreement of trained non-experts and experts was similar. Accuracy of the trained observer measurements was comparable to the expert interobserver agreement and was better for absolute measurements and with three ROIs. The agreement between the one ROI and three ROI methods was good. Absolute thrombus density measurement has superior interobserver agreement compared to relative density measurement. Interobserver variation is smaller when multiple ROIs are used. Trained non-expert observers can accurately and reproducibly assess absolute thrombus densities using three ROIs. (orig.)

  8. Observer variability of absolute and relative thrombus density measurements in patients with acute ischemic stroke

    International Nuclear Information System (INIS)

    Santos, Emilie M.M.; Yoo, Albert J.; Beenen, Ludo F.; Majoie, Charles B.; Berkhemer, Olvert A.; Blanken, Mark D. den; Wismans, Carrie; Niessen, Wiro J.; Marquering, Henk A.

    2016-01-01

    Thrombus density may be a predictor for acute ischemic stroke treatment success. However, only limited data on observer variability for thrombus density measurements exist. This study assesses the variability and bias of four common thrombus density measurement methods by expert and non-expert observers. For 132 consecutive patients with acute ischemic stroke, three experts and two trained observers determined thrombus density by placing three standardized regions of interest (ROIs) in the thrombus and corresponding contralateral arterial segment. Subsequently, absolute and relative thrombus densities were determined using either one or three ROIs. Intraclass correlation coefficient (ICC) was determined, and Bland-Altman analysis was performed to evaluate interobserver and intermethod agreement. Accuracy of the trained observer was evaluated with a reference expert observer using the same statistical analysis. The highest interobserver agreement was obtained for absolute thrombus measurements using three ROIs (ICCs ranging from 0.54 to 0.91). In general, interobserver agreement was lower for relative measurements, and for using one instead of three ROIs. Interobserver agreement of trained non-experts and experts was similar. Accuracy of the trained observer measurements was comparable to the expert interobserver agreement and was better for absolute measurements and with three ROIs. The agreement between the one ROI and three ROI methods was good. Absolute thrombus density measurement has superior interobserver agreement compared to relative density measurement. Interobserver variation is smaller when multiple ROIs are used. Trained non-expert observers can accurately and reproducibly assess absolute thrombus densities using three ROIs. (orig.)

  9. Laser calibration of the ATLAS Tile Calorimeter

    CERN Document Server

    Di Gregorio, Giulia; The ATLAS collaboration

    2017-01-01

    High performance stability of the ATLAS Tile calorimeter is achieved with a set of calibration procedures. One step of the calibrtion procedure is based on measurements of the response stability to laser excitation of the photomultipliers (PMTs) that are used to readout the calorimeter cells. A facility to study in lab the PMT stability response is operating in the PISA-INFN laboratories since 2015. Goals of the test in lab are to study the time evolution of the PMT response to reproduce and to understand the origin of the resonse drifts seen with the PMT mounted on the Tile calorimeter in its normal operation during LHC run I and run II. A new statistical approach was developed to measure the drift of the absolute gain. This approach was applied to both the ATLAS laser calibration data and to the data collected in the Pisa local laboratory. The preliminary results from these two studies are shown.

  10. Calibrations of a tritium extraction facility

    International Nuclear Information System (INIS)

    Bretscher, M.M.; Oliver, B.M.; Farrar, H. IV.

    1983-01-01

    A tritium extraction facility has been built for the purpose of measuring the absolute tritium concentration in neutron-irradiated lithium metal samples. Two independent calibration procedures have been used to determine what fraction, if any, of tritium is lost during the extraction process. The first procedure compares independently measured 4 He and 3 H concentrations from the 6 Li(n,α)T reaction. The second procedure compared measured 6 Li(n,α)T/ 197 Au (n,γ) 198 Au thermal neutron reaction rate ratios with those obtained from Monte Carlo calculations using well-known cross sections. Both calibration methods show that within experimental errors (approx. 1.5%) no tritium is lost during the extraction process

  11. 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

  12. Site Calibration report

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Vesth, Allan

    The report describes site calibration measurements carried out on a site in Denmark. The measurements are carried out in accordance to Ref. [1]. 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...

  13. Absolute Astrometry in the next 50 Years - II

    Science.gov (United States)

    Høg, E.

    2018-01-01

    With the Gaia astrometric satellite in orbit since December 2013 it is time to look at the future of fundamental astrometry and a time frame of 50 years is needed in this matter. A space mission with Gaia-like astrometric performance is required, but not necessarily a Gaia-like satellite. A dozen science issues for a Gaia successor mission in twenty years, with launch about 2035, are presented and in this context also other possibilities for absolute astrometry with milliarcsecond (mas) or sub-mas accuracies are discussed in my report at http://arxiv.org/abs/1408.2190. In brief, the two missions (2013 and 2035) would provide an astrometric foundation for all branches of astronomy from the solar system and stellar systems, including exo-planet systems with long periods, to compact galaxies, quasars and Dark Matter substructures by data which cannot be surpassed in the next 50 years.

  14. The Absolute Normal Scores Test for Symmetry

    Science.gov (United States)

    Penfield, Douglas A.; Sachdeva, Darshan

    1976-01-01

    The absolute normal scores test is described as a test for the symmetry of a distribution of scores about a location parameter. The test is compared to the sign test and the Wilcoxon test as an alternative to the "t"-test. (Editor/RK)

  15. The Theory of Absolute Reaction Rates

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 17; Issue 7. The Theory of Absolute Reaction Rates. Henry Eyring. Classics Volume 17 Issue 7 July 2012 pp 704-711. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/017/07/0704-0711. Author Affiliations.

  16. 49 CFR 236.709 - Block, absolute.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Block, absolute. 236.709 Section 236.709 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION...

  17. Thin-film magnetoresistive absolute position detector

    NARCIS (Netherlands)

    Groenland, J.P.J.

    1990-01-01

    The subject of this thesis is the investigation of a digital absolute posi- tion-detection system, which is based on a position-information carrier (i.e. a magnetic tape) with one single code track on the one hand, and an array of magnetoresistive sensors for the detection of the information on the

  18. Det demokratiske argument for absolut ytringsfrihed

    DEFF Research Database (Denmark)

    Lægaard, Sune

    2014-01-01

    Artiklen diskuterer den påstand, at absolut ytringsfrihed er en nødvendig forudsætning for demokratisk legitimitet med udgangspunkt i en rekonstruktion af et argument fremsat af Ronald Dworkin. Spørgsmålet er, hvorfor ytringsfrihed skulle være en forudsætning for demokratisk legitimitet, og hvorf...

  19. Absolute Distance Measurements with Tunable Semiconductor Laser

    Czech Academy of Sciences Publication Activity Database

    Mikel, Břetislav; Číp, Ondřej; Lazar, Josef

    T118, - (2005), s. 41-44 ISSN 0031-8949 R&D Projects: GA AV ČR(CZ) IAB2065001 Keywords : tunable laser * absolute interferometer Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.661, year: 2004

  20. systemic complications following absolute alcohol embolisation of ...

    African Journals Online (AJOL)

    of the superficial temporal (STA), middle meningeal. (MMA) and occipital ... external jugular vein. Absolute alcohol was injected into the feeder artery using the intermittent pulsed spray technique in aliquots of 1 ml. A total of 55 ml of alcohol was injected. ... cells, vessel wall necrosis resulting in thrombosis and permanent ...

  1. On the absolute measure of Beta activities

    International Nuclear Information System (INIS)

    Sanchez del Rio, C.; Jimenez Reynaldo, O.; Rodriguez Mayquez, E.

    1956-01-01

    A new method for absolute beta counting of solid samples is given. The mea surements is made with an inside Geiger-Muller tube of new construction. The backscattering correction when using an infinite thick mounting is discussed and results for different materials given. (Author)

  2. Absolute tightness: the chemists hesitate to invest

    International Nuclear Information System (INIS)

    Anon.

    1996-01-01

    The safety requirements of industries as nuclear plants and the strengthening of regulations in the field of environment (more particularly those related to volatile organic compounds) have lead the manufacturers to build absolute tightness pumps. But these equipments do not answer all the problems and represent a high investment cost. In consequence, the chemists hesitate to invest. (O.L.)

  3. LARS: An Absolute Reference Spectrograph for solar observations. Upgrade from a prototype to a turn-key system

    Science.gov (United States)

    Löhner-Böttcher, J.; Schmidt, W.; Doerr, H.-P.; Kentischer, T.; Steinmetz, T.; Probst, R. A.; Holzwarth, R.

    2017-10-01

    Context. We designed a Laser-based Absolute Reference Spectrograph (LARS) for ultra-precise solar observations. The high-resolution echelle spectrograph of the Vacuum Tower Telescope is supported by a laser frequency comb to calibrate the solar spectrum on an absolute wavelength scale. In this article, we describe the scientific instrument and focus on the upgrades carried out in the last two years to turn the prototype into a turn-key system. Aims: The goal was to improve the short-term and long-term stability of the systems, and to enable a user-friendly and more versatile operation of the instrument. Methods: The first upgrade involved the modernization of the frequency comb. The laser system generating the comb spectrum was renewed. The Fabry-Pérot cavities were adjusted to filter to a repetition frequency of 8 GHz. A technologically matured photonic crystal fiber was implemented for spectral broadening which simplified and stabilized the setup. The new control software facilitates an automated operation of the frequency comb. The second, quite recent upgrade was performed on the optics which feed the sunlight into a single-mode fiber connected to the spectrograph. A motorized translation stage was deployed to allow the automated selection of three different fields of view with diameters of 1'', 3'', and 10'' for the analysis of the solar spectrum. Results: The successful upgrades allow for long-term observations of up to several hours per day with a stable spectral accuracy of 1 m s-1 limited by the spectrograph. The instrument covers a wavelength range between 480 nm and 700 nm in the visible. Stable, user-friendly operation of the instrument is supported. The selection of the pre-aligned fiber to change the field of view can now be done within seconds. Conclusions: LARS offers the possibility to observe absolute wavelength positions of spectral lines and Doppler velocities in the solar atmosphere. First results demonstrate the capabilities of the instrument

  4. Sandia WIPP calibration traceability

    Energy Technology Data Exchange (ETDEWEB)

    Schuhen, M.D. [Sandia National Labs., Albuquerque, NM (United States); Dean, T.A. [RE/SPEC, Inc., Albuquerque, NM (United States)

    1996-05-01

    This report summarizes the work performed to establish calibration traceability for the instrumentation used by Sandia National Laboratories at the Waste Isolation Pilot Plant (WIPP) during testing from 1980-1985. Identifying the calibration traceability is an important part of establishing a pedigree for the data and is part of the qualification of existing data. In general, the requirement states that the calibration of Measuring and Test equipment must have a valid relationship to nationally recognized standards or the basis for the calibration must be documented. Sandia recognized that just establishing calibration traceability would not necessarily mean that all QA requirements were met during the certification of test instrumentation. To address this concern, the assessment was expanded to include various activities.

  5. Presenting a high accuracy Theta-Phi-style fiber-positioner prototype with a 15-mm pitch

    Science.gov (United States)

    Haeuser, Marco; Lang-Bardl, Florian; Richter, Josef; Hess, Hans-Joachim; Degwert, Adrian; Karasz, Adolf; Kosyra, Ralf; Hopp, Ulrich; Bender, Ralf

    2014-07-01

    We present a Θ - Φ-style fiber-positioner prototype, which will be controlled via the EMI-robust CAN-Bus. Our positioner points without iterations or a metrology system. Due to the overlapping patrol disc of 17.3 mm diameter, we reach a filling factor of 100 %. The positioners diameter is 14.6 mm, containing the control electronics on a contemporary PCB of 13.5 mm width. While moving, the power consumption does not lead to a significant rise in temperature. Given a mechanical reference point measured by stall detection, the absolute accuracy is 27 μm (1σ = 14 µm) and pointings are repeatable with 7 μm (1σ = 4 μm). Better positioning may be reachable with upcoming calibration.

  6. Note: An improved calibration system with phase correction for electronic transformers with digital output.

    Science.gov (United States)

    Cheng, Han-miao; Li, Hong-bin

    2015-08-01

    The existing electronic transformer calibration systems employing data acquisition cards cannot satisfy some practical applications, because the calibration systems have phase measurement errors when they work in the mode of receiving external synchronization signals. This paper proposes an improved calibration system scheme with phase correction to improve the phase measurement accuracy. We employ NI PCI-4474 to design a calibration system, and the system has the potential to receive external synchronization signals and reach extremely high accuracy classes. Accuracy verification has been carried out in the China Electric Power Research Institute, and results demonstrate that the system surpasses the accuracy class 0.05. Furthermore, this system has been used to test the harmonics measurement accuracy of all-fiber optical current transformers. In the same process, we have used an existing calibration system, and a comparison of the test results is presented. The system after improvement is suitable for the intended applications.

  7. A Method to Test Model Calibration Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Judkoff, Ron; Polly, Ben; Neymark, Joel

    2016-08-26

    This paper describes a method for testing model calibration techniques. Calibration is commonly used in conjunction with energy retrofit audit models. An audit is conducted to gather information about the building needed to assemble an input file for a building energy modeling tool. A calibration technique is used to reconcile model predictions with utility data, and then the 'calibrated model' is used to predict energy savings from a variety of retrofit measures and combinations thereof. Current standards and guidelines such as BPI-2400 and ASHRAE-14 set criteria for 'goodness of fit' and assume that if the criteria are met, then the calibration technique is acceptable. While it is logical to use the actual performance data of the building to tune the model, it is not certain that a good fit will result in a model that better predicts post-retrofit energy savings. Therefore, the basic idea here is that the simulation program (intended for use with the calibration technique) is used to generate surrogate utility bill data and retrofit energy savings data against which the calibration technique can be tested. This provides three figures of merit for testing a calibration technique, 1) accuracy of the post-retrofit energy savings prediction, 2) closure on the 'true' input parameter values, and 3) goodness of fit to the utility bill data. The paper will also discuss the pros and cons of using this synthetic surrogate data approach versus trying to use real data sets of actual buildings.

  8. The Calibration Home Base for Imaging Spectrometers

    Directory of Open Access Journals (Sweden)

    Johannes Felix Simon Brachmann

    2016-08-01

    Full Text Available The Calibration Home Base (CHB is an optical laboratory designed for the calibration of imaging spectrometers for the VNIR/SWIR wavelength range. Radiometric, spectral and geometric calibration as well as the characterization of sensor signal dependency on polarization are realized in a precise and highly automated fashion. This allows to carry out a wide range of time consuming measurements in an ecient way. The implementation of ISO 9001 standards in all procedures ensures a traceable quality of results. Spectral measurements in the wavelength range 380–1000 nm are performed to a wavelength uncertainty of +- 0.1 nm, while an uncertainty of +-0.2 nm is reached in the wavelength range 1000 – 2500 nm. Geometric measurements are performed at increments of 1.7 µrad across track and 7.6 µrad along track. Radiometric measurements reach an absolute uncertainty of +-3% (k=1. Sensor artifacts, such as caused by stray light will be characterizable and correctable in the near future. For now, the CHB is suitable for the characterization of pushbroom sensors, spectrometers and cameras. However, it is planned to extend the CHBs capabilities in the near future such that snapshot hyperspectral imagers can be characterized as well. The calibration services of the CHB are open to third party customers from research institutes as well as industry.

  9. Improvement Of The Absolute Activity Determination Technique Of '125I In The Thyroid

    International Nuclear Information System (INIS)

    Pelled, O.; German, U.; Alfassi, Z.

    1999-01-01

    A method for absolute determination of the activity of a 125 I source based on the counting rate values of the 27 keV photons and the 54 keV coincidence photo-peak is given in the literature. We had shown in previous works, that this method, within certain limitations, diminishes the geometry dependence of the activity determination for 125 I sources and for measuring the uptake of 125 I in human thyroid. In the present work we present a farther improvement of the accuracy of the absolute determination method

  10. Absolute linear thermal-expansion measurements on copper and aluminum from 5 to 320 K

    International Nuclear Information System (INIS)

    Kroeger, F.R.; Swenson, C.A.

    1977-01-01

    A linear absolute dilatometer based on a three-terminal parallel-plate capacitor design has been used to obtain thermal expansion data for high-purity copper and aluminum from 5 to 320 K. These data have an absolute accuracy of +- 0.1% above 20 K for copper and above 30 K for aluminum, and agree well with published data at the higher temperatures. The disagreement which exists with other data below 5 K for copper and below 15 K for aluminum is believed to be sample dependent, but the mechanism is not known. The aluminum results in this region depend on the state of annealing of the sample

  11. Assignment of absolute stereostructures through quantum mechanics electronic and vibrational circular dichroism calculations.

    Science.gov (United States)

    Dai, Peng; Jiang, Nan; Tan, Ren-Xiang

    2016-01-01

    Elucidation of absolute configuration of chiral molecules including structurally complex natural products remains a challenging problem in organic chemistry. A reliable method for assigning the absolute stereostructure is to combine the experimental circular dichroism (CD) techniques such as electronic and vibrational CD (ECD and VCD), with quantum mechanics (QM) ECD and VCD calculations. The traditional QM methods as well as their continuing developments make them more applicable with accuracy. Taking some chiral natural products with diverse conformations as examples, this review describes the basic concepts and new developments of QM approaches for ECD and VCD calculations in solution and solid states.

  12. Evaluating least absolute deviation regression as an inverse model in groundwater flow calibration

    Science.gov (United States)

    Huddleston, John Matthew

    Though information regarding children's mental health is increasing, and we know that approximately 20% of children meet criteria for a mental disorder, little is known about the characteristics of the child client population at community mental health clinics. This study is an exploratory analysis of the demographic and treatment characteristics of the child client population at a psychology training clinic/community mental health center. Demographic and treatment information is presented and compared across various service categories as well as diagnostic categories. Comparisons between those served during the first six years and those served during the second six years of the study period are also made. Results are discussed in terms of generalizability of results as well as available information from the literature.

  13. Absolute calibration of photon-number-resolving detectors with an analog output using twin beams

    Czech Academy of Sciences Publication Activity Database

    Peřina Jr., J.; Haderka, Ondřej; Allevi, A.; Bondani, M.

    2014-01-01

    Roč. 104, č. 4 (2014), "041113-1"-"041113-4" ISSN 0003-6951 R&D Projects: GA ČR GAP205/12/0382 Institutional support: RVO:68378271 Keywords : photon- number resolving detector * twin beams * photon fields Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.302, year: 2014

  14. Absolute Infrared Calibration of Standard Stars by the Midcourse Space Experiment

    Science.gov (United States)

    2004-04-01

    the MSX satellite to the X-band receiver at the Applied Physics Laboratory (APL) of the Johns Hopkins University in Columbia, MD was recorded as Level...Cohen (private communication) noted that N band photometry by John Africano at the Air Force Maui Optical Site did show an episodic 0.1 magnitude...Cohen, M., Galliano , E., Loup, C., Alard, C., de Batz, B., Bertin, E., Borsenberger, J., Cioni, M. R., Copet, E., Dennefeld, M., Derriere, S., Deul, E

  15. A novel capacitive absolute positioning sensor based on time grating with nanometer resolution

    Science.gov (United States)

    Pu, Hongji; Liu, Hongzhong; Liu, Xiaokang; Peng, Kai; Yu, Zhicheng

    2018-05-01

    The present work proposes a novel capacitive absolute positioning sensor based on time grating. The sensor includes a fine incremental-displacement measurement component combined with a coarse absolute-position measurement component to obtain high-resolution absolute positioning measurements. A single row type sensor was proposed to achieve fine displacement measurement, which combines the two electrode rows of a previously proposed double-row type capacitive displacement sensor based on time grating into a single row. To achieve absolute positioning measurement, the coarse measurement component is designed as a single-row type displacement sensor employing a single spatial period over the entire measurement range. In addition, this component employs a rectangular induction electrode and four groups of orthogonal discrete excitation electrodes with half-sinusoidal envelope shapes, which were formed by alternately extending the rectangular electrodes of the fine measurement component. The fine and coarse measurement components are tightly integrated to form a compact absolute positioning sensor. A prototype sensor was manufactured using printed circuit board technology for testing and optimization of the design in conjunction with simulations. Experimental results show that the prototype sensor achieves a ±300 nm measurement accuracy with a 1 nm resolution over a displacement range of 200 mm when employing error compensation. The proposed sensor is an excellent alternative to presently available long-range absolute nanometrology sensors owing to its low cost, simple structure, and ease of manufacturing.

  16. Radiation protection instrumentation test and calibration

    International Nuclear Information System (INIS)

    Selby, J.M.; Larson, H.V.; Bartlett, W.T.; Mulhern, O.R.; Fleming, D.M.

    1978-01-01

    The operational requirements of radiation protection instrumentation are set forth in the recommendations of various commissions and committees. Additionally, the user may establish the need for different or more restrictive requirements. The ability to meet these requirements will depend not only on the instrument capabilities but also on periodic recalibrations, preventative maintenance and testing of the instruments. A new standard, ANSI N323, ''Radiation Protection Instrumentation Test and Calibration'', has been prepared and approved for use in the USA. This standard establishes calibration methods for portable radiation protection instruments used for detection and measurement of levels of ionizing radiation fields or levels of radioactive surface contamination. Included within the scope of this standard are conditions, equipment and techniques for calibration, as well as the degree of precision and accuracy required. The salient points of the new standard will be presented in the paper. The nature of improvements at our laboratory required by the standard will be discussed. (author)

  17. The Absolute Shielding Constants of Heavy Nuclei: Resolving the Enigma of the (119)Sn Absolute Shielding.

    Science.gov (United States)

    Malkin, Elena; Komorovsky, Stanislav; Repisky, Michal; Demissie, Taye B; Ruud, Kenneth

    2013-02-07

    We demonstrate that the apparent disagreement between experimental determinations and four-component relativistic calculations of the absolute shielding constants of heavy nuclei is due to the breakdown of the commonly assumed relation between the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the NMR shielding constants. We demonstrate that this breakdown has significant consequences for the absolute shielding constant of (119)Sn, leading to errors of about 1000 ppm. As a consequence, we expect that many absolute shielding constants of heavy nuclei will be in need of revision.

  18. Remote calibration system of a smart electrical energy meter

    Directory of Open Access Journals (Sweden)

    Zakariae Jebroni

    2017-12-01

    Full Text Available The need to control the power grid in real time has opened a new field of research, today researchers are trying to design electrical meters that are completely remote controlled, to create an advanced metering infrastructure. One of the most important processes in the field of measurement is the calibration of measuring instruments. The calibration process of the electrical meters was performed at laboratories. However, the new directives, now, require a regular test of accuracy. Nevertheless, moving each time on site to check the accuracy of a meter can be annoying. To solve this problem our contribution is to propose a new structure of a smart meter that integrates a calibration card, so that, this process is carried out remotely. To be able to calibrate the meter or test its accuracy, we have included an AC-AC converter powered by the electrical grid and that provides a stable voltage independent of the electrical grid in term of frequency and amplitude. The output voltage of the converter is used as the reference signal during calibration or accuracy testing. In this paper, we will present the structure of the calibration card, the study and dimensioning of the converter, as well as the control technique used to eliminate variations of the input voltage. At the end, we will present the results of simulations and experiments.

  19. Soil moisture calibration of TDR multilevel probes

    Directory of Open Access Journals (Sweden)

    Serrarens Daniel

    2000-01-01

    Full Text Available Time domain reflectometry (TDR probes are increasingly used for field estimation of soil water content. The objective of this study was to evaluate the accuracy of the multilevel TDR probe under field conditions. For this purpose, eight such TDR probes were installed in small plots that were seeded with beans and sorghum. Data collection from the probes was such that soil moisture readings were automated and logged using a standalone field unit. Neutron probe measurements were used to calibrate the TDR probes. Soil-probe contact and soil compaction were critical to the accuracy of the TDR, especially when a number of TDR probes are combined for a single calibration curve. If each probe is calibrated individually, approximate measurement errors were between 0.005 and 0.015 m³ m-3. However, measurement errors doubled to approximately 0.025 to 0.03 m³ m-3, when TDR probes were combined to yield a single calibration curve.

  20. A photon pressure calibrator for the GEO 600 gravitational wave detector

    International Nuclear Information System (INIS)

    Mossavi, K.; Hewitson, M.; Hild, S.; Seifert, F.; Weiland, U.; Smith, J.R.; Lueck, H.; Grote, H.; Willke, B.; Danzmann, K.

    2006-01-01

    Interferometer mirror displacement induced by radiation pressure is used to demonstrate an alternative calibration method for the GEO 600 detector. The photon calibrator utilizes an amplitude modulated laser diode with up to 1.4 W output power at a wavelength of 1035 nm. The achieved accuracy of the strain amplitude calibration is dominated by the laser power calibration error, which is in the range of ±4% for the measurements presented in this Letter

  1. Lidar to lidar calibration

    DEFF Research Database (Denmark)

    Fernandez Garcia, Sergio; Villanueva, Héctor

    This report presents the result of the lidar to lidar calibration performed for ground-based lidar. Calibration is here understood as the establishment of a relation between the reference lidar wind speed measurements with measurement uncertainties provided by measurement standard and corresponding...... lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from the reference lidar measurements are given for information only....

  2. A highly accurate absolute gravimetric network for Albania, Kosovo and Montenegro

    Science.gov (United States)

    Ullrich, Christian; Ruess, Diethard; Butta, Hubert; Qirko, Kristaq; Pavicevic, Bozidar; Murat, Meha

    2016-04-01

    The objective of this project is to establish a basic gravity network in Albania, Kosovo and Montenegro to enable further investigations in geodetic and geophysical issues. Therefore the first time in history absolute gravity measurements were performed in these countries. The Norwegian mapping authority Kartverket is assisting the national mapping authorities in Kosovo (KCA) (Kosovo Cadastral Agency - Agjencia Kadastrale e Kosovës), Albania (ASIG) (Autoriteti Shtetëror i Informacionit Gjeohapësinor) and in Montenegro (REA) (Real Estate Administration of Montenegro - Uprava za nekretnine Crne Gore) in improving the geodetic frameworks. The gravity measurements are funded by Kartverket. The absolute gravimetric measurements were performed from BEV (Federal Office of Metrology and Surveying) with the absolute gravimeter FG5-242. As a national metrology institute (NMI) the Metrology Service of the BEV maintains the national standards for the realisation of the legal units of measurement and ensures their international equivalence and recognition. Laser and clock of the absolute gravimeter were calibrated before and after the measurements. The absolute gravimetric survey was carried out from September to October 2015. Finally all 8 scheduled stations were successfully measured: there are three stations located in Montenegro, two stations in Kosovo and three stations in Albania. The stations are distributed over the countries to establish a gravity network for each country. The vertical gradients were measured at all 8 stations with the relative gravimeter Scintrex CG5. The high class quality of some absolute gravity stations can be used for gravity monitoring activities in future. The measurement uncertainties of the absolute gravity measurements range around 2.5 micro Gal at all stations (1 microgal = 10-8 m/s2). In Montenegro the large gravity difference of 200 MilliGal between station Zabljak and Podgorica can be even used for calibration of relative gravimeters

  3. A New Automated Instrument Calibration Facility at the Savannah River Site

    International Nuclear Information System (INIS)

    Polz, E.; Rushton, R.O.; Wilkie, W.H.; Hancock, R.C.

    1998-01-01

    The Health Physics Instrument Calibration Facility at the Savannah River Site in Aiken, SC was expressly designed and built to calibrate portable radiation survey instruments. The facility incorporates recent advances in automation technology, building layout and construction, and computer software to improve the calibration process. Nine new calibration systems automate instrument calibration and data collection. The building is laid out so that instruments are moved from one area to another in a logical, efficient manner. New software and hardware integrate all functions such as shipping/receiving, work flow, calibration, testing, and report generation. Benefits include a streamlined and integrated program, improved efficiency, reduced errors, and better accuracy

  4. Fast Calibration of Industrial Mobile Robots to Workstations using QR Codes

    DEFF Research Database (Denmark)

    Andersen, Rasmus Skovgaard; Damgaard, Jens Skov; Madsen, Ole

    2013-01-01

    a wide variety of tasks, while at the same time being fast and easy to configure and program. When an AIMM moves from one workstation to another, it is essential that it is able to calibrate its position with respect to that new station. In this paper, a new and fast calibration method based on QR codes...... is proposed. With this QR calibration, it is possible to calibrate an AIMM to a workstation in 3D in less than 1 second, which is significantly faster than existing methods. The accuracy of the calibration is ±4 mm. The method is modular in the sense that it directly supports integration and calibration...

  5. Calibration Fixture For Anemometer Probes

    Science.gov (United States)

    Lewis, Charles R.; Nagel, Robert T.

    1993-01-01

    Fixture facilitates calibration of three-dimensional sideflow thermal anemometer probes. With fixture, probe oriented at number of angles throughout its design range. Readings calibrated as function of orientation in airflow. Calibration repeatable and verifiable.

  6. WE-G-BRB-08: TG-51 Calibration of First Commercial MRI-Guided IMRT System in the Presence of 0.35 Tesla Magnetic Field.

    Science.gov (United States)

    Goddu, S; Green, O Pechenaya; Mutic, S

    2012-06-01

    The first real-time-MRI-guided radiotherapy system has been installed in a clinic and it is being evaluated. Presence of magnetic field (MF) during radiation output calibration may have implications on ionization measurements and there is a possibility that standard calibration protocols may not be suitable for dose measurements for such devices. In this study, we evaluated whether a standard calibration protocol (AAPM- TG-51) is appropriate for absolute dose measurement in presence of MF. Treatment delivery of the ViewRay (VR) system is via three 15,000Ci Cobalt-60 heads positioned 120-degrees apart and all calibration measurements were done in the presence of 0.35T MF. Two ADCL- calibrated ionization-chambers (Exradin A12, A16) were used for TG-51 calibration. Chambers were positioned at 5-cm depth, (SSD=105cm: VR's isocenter), and the MLC leaves were shaped to a 10.5cm × 10.5 cm field size. Percent-depth-dose (PDD) measurements were performed for 5 and 10 cm depths. Individual output of each head was measured using the AAPM- TG51 protocol. Calibration accuracy for each head was subsequently verified by Radiological Physics Center (RPC) TLD measurements. Measured ion-recombination (Pion) and polarity (Ppol) correction factors were less-than 1.002 and 1.006, respectively. Measured PDDs agreed with BJR-25 within ±0.2%. Maximum dose rates for the reference field size at VR's isocenter for heads 1, 2 and 3 were 1.445±0.005, 1.446±0.107, 1.431±0.006 Gy/minute, respectively. Our calibrations agreed with RPC- TLD measurements within ±1.3%, ±2.6% and ±2.0% for treatment-heads 1, 2 and 3, respectively. At the time of calibration, mean activity of the Co-60 sources was 10,800Ci±0.1%. This study shows that the TG- 51 calibration is feasible in the presence of 0.35T MF and the measurement agreement is within the range of results obtainable for conventional treatment machines. Drs. Green, Goddu, and Mutic served as scientific consultants for ViewRay, Inc. Dr. Mutic

  7. Laboratory Calibration of a Field Imaging Spectrometer System

    Directory of Open Access Journals (Sweden)

    Qingxi Tong

    2011-02-01

    Full Text Available A new Field Imaging Spectrometer System (FISS based on a cooling area CCD was developed. This paper describes the imaging principle, structural design, and main parameters of the FISS sensor. The FISS was spectrally calibrated with a double grating monochromator to determine the center wavelength and FWHM of each band. Calibration results showed that the spectral range of the FISS system is 437–902 nm, the number of channels is 344 and the spectral resolution of each channel is better than 5 nm. An integrating sphere was used to achieve absolute radiometric calibration of the FISS with less than 5% calibration error for each band. There are 215 channels with signal to noise ratios (SNRs greater than 500 (62.5% of the bands. The results demonstrated that the FISS has achieved high performance that assures the feasibility of its practical use in various fields.

  8. EUV mirror based absolute incident flux detector

    Science.gov (United States)

    Berger, Kurt W.

    2004-03-23

    A device for the in-situ monitoring of EUV radiation flux includes an integrated reflective multilayer stack. This device operates on the principle that a finite amount of in-band EUV radiation is transmitted through the entire multilayer stack. This device offers improvements over existing vacuum photo-detector devices since its calibration does not change with surface contamination.

  9. From Hubble's NGSL to Absolute Fluxes

    Science.gov (United States)

    Heap, Sara R.; Lindler, Don

    2012-01-01

    Hubble's Next Generation Spectral Library (NGSL) consists of R-l000 spectra of 374 stars of assorted temperature, gravity, and metallicity. Each spectrum covers the wavelength range, 0.18-1.00 microns. The library can be viewed and/or downloaded from the website, http://archive.stsci.edu/prepds/stisngsll. Stars in the NGSL are now being used as absolute flux standards at ground-based observatories. However, the uncertainty in the absolute flux is about 2%, which does not meet the requirements of dark-energy surveys. We are therefore developing an observing procedure that should yield fluxes with uncertainties less than 1 % and will take part in an HST proposal to observe up to 15 stars using this new procedure.

  10. Trapped individual ion at absolute zero temperature

    Science.gov (United States)

    Yu, Nan; Dehmelt, Hans; Nagourney, Warren

    1989-01-01

    Laser cooling and ion trapping have progressed to such an extent that one can now speak of realizing a confined atom at absolute zero temperature. In this short publication, we analyze an experiment toward such realization using a single Ba+ ion in a miniature rf trap. The Ba+ ion is first laser-cooled to the limit where the ion spends most of its time in the zero-point energy state. Then a test sequence allows one to verify whether or not the ion is actually in its zero-point state. The test sequence may also serve as a device for state selection of an atom at absolute zero temperature. PMID:16594054

  11. Interpolation of uniformly absolutely continuous operators

    Czech Academy of Sciences Publication Activity Database

    Cobos, F.; Gogatishvili, Amiran; Opic, B.; Pick, L.

    2013-01-01

    Roč. 286, 5-6 (2013), s. 579-599 ISSN 0025-584X R&D Projects: GA ČR GA201/08/0383 Institutional support: RVO:67985840 Keywords : uniformly absolutely continuous operators * interpolation * type of an interpolation method Subject RIV: BA - General Mathematics Impact factor: 0.658, year: 2013 http://onlinelibrary.wiley.com/doi/10.1002/ mana .201100205/full

  12. Absolute spectrophotometry of the β Lyr

    International Nuclear Information System (INIS)

    Burnashev, V.I.; Skul'skij, M.Yu.

    1978-01-01

    In 1974 an absolute spectrophotometry of β Lyr was performed with the scanning spectrophotometer in the 3300-7400 A range. The energy distribution in the β Lyr spectrum is obtained. The β Lyr model is proposed. It is shown, that the continuous spectrum of the β Lyr radiation can be presented by the total radiation of the B8 3 and A5 3 two stars and of the gaseous envelope with Te =20000 K

  13. Benzofuranoid and bicyclooctanoid neolignans:absolute configuration

    International Nuclear Information System (INIS)

    Alvarenga, M.A. de; Giesbrecht, A.M.; Gottlieb, O.R.; Yoshida, M.

    1977-01-01

    The naturally occuring benzofuranoid and bicyclo (3,2,1) octanoid neolignans have their relative configurations established by 1 H and 13 C NMR, inclusively with aid of the solvent shift technique. Interconversion of the benzofuranoid type compounds, as well as for a benzofuranoid to a bicyclooctanoid derivate, make ORD correlations, ultimately with (2S, 3S) - and (2R,3R)-2,3- dihydrobenzofurans, possible, and led to the absolute configurations of both series of neolignans [pt

  14. SRHA calibration curve

    Data.gov (United States)

    U.S. Environmental Protection Agency — an UV calibration curve for SRHA quantitation. This dataset is associated with the following publication: Chang, X., and D. Bouchard. Surfactant-Wrapped Multiwalled...

  15. Calibrated Properties Model

    Energy Technology Data Exchange (ETDEWEB)

    C. Ahlers; H. Liu

    2000-03-12

    The purpose of this Analysis/Model Report (AMR) is to document the Calibrated Properties Model that provides calibrated parameter sets for unsaturated zone (UZ) flow and transport process models for the Yucca Mountain Site Characterization Project (YMP). This work was performed in accordance with the ''AMR Development Plan for U0035 Calibrated Properties Model REV00. These calibrated property sets include matrix and fracture parameters for the UZ Flow and Transport Model (UZ Model), drift seepage models, drift-scale and mountain-scale coupled-processes models, and Total System Performance Assessment (TSPA) models as well as Performance Assessment (PA) and other participating national laboratories and government agencies. These process models provide the necessary framework to test conceptual hypotheses of flow and transport at different scales and predict flow and transport behavior under a variety of climatic and thermal-loading conditions.

  16. Calibrated Properties Model

    Energy Technology Data Exchange (ETDEWEB)

    C.F. Ahlers, H.H. Liu

    2001-12-18

    The purpose of this Analysis/Model Report (AMR) is to document the Calibrated Properties Model that provides calibrated parameter sets for unsaturated zone (UZ) flow and transport process models for the Yucca Mountain Site Characterization Project (YMP). This work was performed in accordance with the AMR Development Plan for U0035 Calibrated Properties Model REV00 (CRWMS M&O 1999c). These calibrated property sets include matrix and fracture parameters for the UZ Flow and Transport Model (UZ Model), drift seepage models, drift-scale and mountain-scale coupled-processes models, and Total System Performance Assessment (TSPA) models as well as Performance Assessment (PA) and other participating national laboratories and government agencies. These process models provide the necessary framework to test conceptual hypotheses of flow and transport at different scales and predict flow and transport behavior under a variety of climatic and thermal-loading conditions.

  17. Traceable Pyrgeometer Calibrations

    Energy Technology Data Exchange (ETDEWEB)

    Dooraghi, Mike; Kutchenreiter, Mark; Reda, Ibrahim; Habte, Aron; Sengupta, Manajit; Andreas, Afshin; Newman, Martina; Webb, Craig

    2016-05-02

    This presentation provides a high-level overview of the progress on the Broadband Outdoor Radiometer Calibrations for all shortwave and longwave radiometers that are deployed by the Atmospheric Radiation Measurement program.

  18. 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.

  19. Site Calibration, FGW

    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....

  20. Air Data Calibration Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This facility is for low altitude subsonic altimeter system calibrations of air vehicles. Mission is a direct support of the AFFTC mission. Postflight data merge is...

  1. Calibration of thermoluminiscent materials

    International Nuclear Information System (INIS)

    Bos, A.J.J.

    1989-07-01

    In this report the relation between exposure and absorbed radiation dose in various materials is represented, on the base of recent data. With the help of this a calibration procedure for thermoluminescent materials, adapted to the IRI radiation standard is still the exposure in rontgen. In switching to the air kerma standard the calibration procedure will have to be adapted. (author). 6 refs.; 4 tabs

  2. Approximation Behooves Calibration

    DEFF Research Database (Denmark)

    da Silva Ribeiro, André Manuel; Poulsen, Rolf

    2013-01-01

    Calibration based on an expansion approximation for option prices in the Heston stochastic volatility model gives stable, accurate, and fast results for S&P500-index option data over the period 2005–2009.......Calibration based on an expansion approximation for option prices in the Heston stochastic volatility model gives stable, accurate, and fast results for S&P500-index option data over the period 2005–2009....

  3. Calibration of the ZEUS forward calorimeter

    International Nuclear Information System (INIS)

    Kraemer, M.

    1990-10-01

    The physics at the ep-collider HERA requires high resolution calorimetry calibrated with an accuracy of better than 2%. The ZEUS detector meets these conditions by means of a compensating uranium scintillator sandwich calorimeter with an energy resolution of σ/E = 35%/√E + σ cal , where σ cal is the calibration error. One of the tools to minimize σ cal is the calibration with the signals of the radioactivity of the Uranium plates (UNO). Taking UNO data every 8 hours keeps the calibration stable within ≅ 1%. The muon calibration is done employing an algorithm, that determines the most probable energy loss with a precision of ≅ 1%. The channel-to-channel fluctuations of the ratio μ/UNO for a forward calorimeter (FCAL) prototype show a spread of 5.2% for the electromagnetic calorimeter and ≅ 2.5% for the hadronic sections. Improvements in the construction of the FCAL modules decreased these fluctuations to 2.0% and ≅ 1.8% respectively. The influence of the cracks between the calorimeter modules amounts to ≅ 1.7% on average for the ZEUS geometry, if a 2 mm thick Pb-sheet is introduced between the modules. We conclude that we are able to keep σ cal below 2%. (orig.)

  4. Jet Calibration at ATLAS

    CERN Document Server

    Camacho, R; The ATLAS collaboration

    2011-01-01

    The accurate measurement of jets at high transverse momentum produced in proton proton collision at a centre of mass energy at \\sqrt(s)=7 TeV is important in many physics analysis at LHC. Due to the non-compensating nature of the ATLAS calorimeter, signal losses due to noise thresholds and in dead material the jet energy needs to be calibrated. Presently, the ATLAS experiment derives the jet calibration from Monte Carlo simulation using a simple correction that relates the true and the reconstructed jet energy. The jet energy scale and its uncertainty are derived from in-situ measurements and variation in the Monte Carlo simulation. Other calibration schemes have been also developed, they use hadronic cell calibrations or the topology of the jet constituents to reduce hadronic fluctuations in the jet response, improving in that way the jet resolution. The performances of the various calibration schemes using data and simulation, the evaluation of the modelling of the properties used to derive each calibration...

  5. Calibrating nacelle lidars

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, M.

    2013-01-15

    Nacelle mounted, forward looking wind lidars are beginning to be used to provide reference wind speed measurements for the power performance testing of wind turbines. In such applications, a formal calibration procedure with a corresponding uncertainty assessment will be necessary. This report presents four concepts for performing such a nacelle lidar calibration. Of the four methods, two are found to be immediately relevant and are pursued in some detail. The first of these is a line of sight calibration method in which both lines of sight (for a two beam lidar) are individually calibrated by accurately aligning the beam to pass close to a reference wind speed sensor. A testing procedure is presented, reporting requirements outlined and the uncertainty of the method analysed. It is seen that the main limitation of the line of sight calibration method is the time required to obtain a representative distribution of radial wind speeds. An alternative method is to place the nacelle lidar on the ground and incline the beams upwards to bisect a mast equipped with reference instrumentation at a known height and range. This method will be easier and faster to implement and execute but the beam inclination introduces extra uncertainties. A procedure for conducting such a calibration is presented and initial indications of the uncertainties given. A discussion of the merits and weaknesses of the two methods is given together with some proposals for the next important steps to be taken in this work. (Author)

  6. The correction of vibration in frequency scanning interferometry based absolute distance measurement system for dynamic measurements

    Science.gov (United States)

    Lu, Cheng; Liu, Guodong; Liu, Bingguo; Chen, Fengdong; Zhuang, Zhitao; Xu, Xinke; Gan, Yu

    2015-10-01

    Absolute distance measurement systems are of significant interest in the field of metrology, which could improve the manufacturing efficiency and accuracy of large assemblies in fields such as aircraft construction, automotive engineering, and the production of modern windmill blades. Frequency scanning interferometry demonstrates noticeable advantages as an absolute distance measurement system which has a high precision and doesn't depend on a cooperative target. In this paper , the influence of inevitable vibration in the frequency scanning interferometry based absolute distance measurement system is analyzed. The distance spectrum is broadened as the existence of Doppler effect caused by vibration, which will bring in a measurement error more than 103 times bigger than the changes of optical path difference. In order to decrease the influence of vibration, the changes of the optical path difference are monitored by a frequency stabilized laser, which runs parallel to the frequency scanning interferometry. The experiment has verified the effectiveness of this method.

  7. Absolute Hydration Free Energy of Proton from First Principles Electronic Structure Calculations

    International Nuclear Information System (INIS)

    Zhan, Chang-Guo; Dixon, David A.

    2001-01-01

    The absolute hydration free energy of the proton, DGhyd298(H+), is one of the fundamental quantities for the thermodynamics of aqueous systems. Its exact value remains unknown despite extensive experimental and computational efforts. We report a first-principles determination of DGhyd298(H+) by using the latest developments in electronic structure theory and massively parallel computers. DGhyd298(H+) is accurately predicted to be -262.4 kcal/mol based on high-level, first-principles solvation-included electronic structure calculations. The absolute hydration free energies of other cations can be obtained by using appropriate available thermodynamic data in combination with this value. The high accuracy of the predicted absolute hydration free energy of proton is confirmed by applying the same protocol to predict DGhyd298(Li+)

  8. Absolute Soft X-ray Emission Measurements at the Nike Laser

    Science.gov (United States)

    Weaver, J.; Atkin, R.; Boyer, C.; Colombant, D.; Feldman, U.; Fielding, D.; Gardner, J.; Holland, G.; Klapisch, M.; Mostovych, A. N.; Obenscain, S.; Seely, J. F.

    2002-11-01

    Recent experiments at the Nike laser facility have demonstrated that, when a low intensity prepulse ( 2main laser intensity) is used to heat a thin Au or Pd coating on a planar CH target, the growth of non-uniformities due to laser imprint can be reduced from the growth observed for an uncoated CH target. The absolute radiation intensity in the soft x-ray region (0.1-1 keV) has a important role in the energy balance for layered targets. There is an ongoing effort to characterize the soft x-ray emission using an absolutely calibrated transmission grating spectrometer and filtered diode modules. Measurements of the angular distribution of the emission from unlayered solid targets (Au, Pd, CH) have recently been made using an array of moveable filtered diode modules. The data from the angular distribution studies will be presented. A new absolutely calibrated, time-resolving transmission grating spectrometer has been installed at the Nike. The new version has improved spectral resolution, selectable transmission filters, and the potential for simultaneous temporal, spatial, and spectral resolution. Preliminary data from the new spectrometer will be presented and future experiments will be briefly discussed. *Work was supported by DoE

  9. Method for determining the absolute number concentration of nanoparticles from electrospray sources.

    Science.gov (United States)

    Li, Mingdong; Guha, Suvajyoti; Zangmeister, Rebecca; Tarlov, Michael J; Zachariah, Michael R

    2011-12-20

    We have developed a simple, fast, and accurate method to measure the absolute number concentration of nanoparticles in solution. The method combines electrospray differential mobility analysis (ES-DMA) with a statistical analysis of droplet-induced oligomer formation. A key feature of the method is that it allows determination of the absolute number concentration of particles by knowing only the droplet size generated from a particular ES source, thereby eliminating the need for sample-specific calibration standards or detailed analysis of transport losses. The approach was validated by comparing the total number concentration of monodispersed Au nanoparticles determined by ES-DMA with UV/vis measurements. We also show that this approach is valid for protein molecules by quantifying the absolute number concentration of Rituxan monoclonal antibody in solution. The methodology is applicable for quantification of any electrospray process coupled to an analytical tool that can distinguish monomers from higher order oligomers. The only requirement is that the droplet size distribution be evaluated. For users only interested in implementation of the theory, we provide a section that summarizes the relevant formulas. This method eliminates the need for sample-specific calibration standards or detailed analysis of transport losses. © 2011 American Chemical Society

  10. Regional neonatal brain absolute thermometry by 1H MRS.

    Science.gov (United States)

    Bainbridge, Alan; Kendall, Giles S; De Vita, Enrico; Hagmann, Cornelia; Kapetanakis, Andrew; Cady, Ernest B; Robertson, Nicola J

    2013-04-01

    Therapeutic hypothermia is standard care for infants with moderate to severe encephalopathy. (1) H MRS thermometry (MRSt) measures regional brain absolute temperature using the temperature-dependent water chemical shift. This study evaluates the clinical feasibility of MRSt in human neonates, and correlates white matter (WM) and thalamus (Thal) MRSt with conventional rectal temperature (Trectal ) measurement. Fifty-six infants born at term underwent perinatal MRSt for suspected hypoxic-ischaemic brain injury and 33 infants born preterm had MRSt at a term-equivalent age; 56 of the 89 had Trectal measured after MRSt of either a Thal or posterior WM voxel, or both. MRSt used point-resolved spectroscopy (no water suppression; TR = 1370 ms; TE = 288 ms; 1.5 × 1.5 × 1.5 cm(3) Thal and 1.1 × 1.3 × 1.4 cm(3) WM voxels). Time domain data were phase and frequency corrected before summation and motion-corrupted data were excluded from further analysis using simple criteria [preprocessing + quality assurance (QA)]. Two published water temperature-dependence calibrations [both using cerebral creatine (Cr), choline (Cho) and N-acetylaspartate (Naa) as independent reference peaks] were compared. The temperature measurements derived from Cr, Cho and Naa were combined to give a single amplitude-weighted combination temperature (TAWC ). WM and Thal TAWC correlated linearly with Trectal (Thal slope, 0.82 ± 0.04, R(2) = 0.85, p < 0.05; WM slope, 0.95 ± 0.04, R(2) = 0.78, p < 0.05). Preprocessing + QA improved the correlation between WM TAWC and Trectal (R(2) increased from 0.27 to 0.78, p < 0.001). Both calibration datasets showed specific inconsistencies between the temperatures calculated using Cr, Cho and Naa reference peaks when applied to this neonatal dataset. Neonatal MRSt is clinically feasible. Preprocessing + QA improved MRSt reliability in WM. The consideration of MRSt calibration internal biases is necessary before combining MRSt temperatures from multiple

  11. Accuracy of force and center of pressure measures of the Wii Balance Board.

    Science.gov (United States)

    Bartlett, Harrison L; Ting, Lena H; Bingham, Jeffrey T

    2014-01-01

    The Nintendo Wii Balance Board (WBB) is increasingly used as an inexpensive force plate for assessment of postural control; however, no documentation of force and COP accuracy and reliability is publicly available. Therefore, we performed a standard measurement uncertainty analysis on 3 lightly and 6 heavily used WBBs to provide future users with information about the repeatability and accuracy of the WBB force and COP measurements. Across WBBs, we found the total uncertainty of force measurements to be within ± 9.1N, and of COP location within ± 4.1mm. However, repeatability of a single measurement within a board was better (4.5 N, 1.5mm), suggesting that the WBB is best used for relative measures using the same device, rather than absolute measurement across devices. Internally stored calibration values were comparable to those determined experimentally. Further, heavy wear did not significantly degrade performance. In combination with prior evaluation of WBB performance and published standards for measuring human balance, our study provides necessary information to evaluate the use of the WBB for analysis of human balance control. We suggest the WBB may be useful for low-resolution measurements, but should not be considered as a replacement for laboratory-grade force plates. Published by Elsevier B.V.

  12. Measuring true localization accuracy in super resolution microscopy with DNA-origami nanostructures

    International Nuclear Information System (INIS)

    Reuss, Matthias; Blom, Hans; Brismar, Hjalmar; Fördős, Ferenc; Högberg, Björn; Öktem, Ozan

    2017-01-01

    A common method to assess the performance of (super resolution) microscopes is to use the localization precision of emitters as an estimate for the achieved resolution. Naturally, this is widely used in super resolution methods based on single molecule stochastic switching. This concept suffers from the fact that it is hard to calibrate measures against a real sample (a phantom), because true absolute positions of emitters are almost always unknown. For this reason, resolution estimates are potentially biased in an image since one is blind to true position accuracy, i.e. deviation in position measurement from true positions. We have solved this issue by imaging nanorods fabricated with DNA-origami. The nanorods used are designed to have emitters attached at each end in a well-defined and highly conserved distance. These structures are widely used to gauge localization precision. Here, we additionally determined the true achievable localization accuracy and compared this figure of merit to localization precision values for two common super resolution microscope methods STED and STORM. (paper)

  13. Measuring true localization accuracy in super resolution microscopy with DNA-origami nanostructures

    Science.gov (United States)

    Reuss, Matthias; Fördős, Ferenc; Blom, Hans; Öktem, Ozan; Högberg, Björn; Brismar, Hjalmar

    2017-02-01

    A common method to assess the performance of (super resolution) microscopes is to use the localization precision of emitters as an estimate for the achieved resolution. Naturally, this is widely used in super resolution methods based on single molecule stochastic switching. This concept suffers from the fact that it is hard to calibrate measures against a real sample (a phantom), because true absolute positions of emitters are almost always unknown. For this reason, resolution estimates are potentially biased in an image since one is blind to true position accuracy, i.e. deviation in position measurement from true positions. We have solved this issue by imaging nanorods fabricated with DNA-origami. The nanorods used are designed to have emitters attached at each end in a well-defined and highly conserved distance. These structures are widely used to gauge localization precision. Here, we additionally determined the true achievable localization accuracy and compared this figure of merit to localization precision values for two common super resolution microscope methods STED and STORM.

  14. Calibration of the CMS Electromagnetic Calorimeter with LHC collision data

    CERN Document Server

    Obertino, Margherita Maria

    2012-01-01

    The CMS ECAL is one of the highest resolution electromagnetic calorimeters ever constructed, but relies upon precision calibration in order to achieve and maintain its design performance. Variations in light collected from the lead tungstate crystals, due to intrinsic differences in crystals/photodetectors, as well as variations with time due to radiation damage for example, need to be taken into account. Sophisticated and effective methods of inter-crystal and absolute calibration have been devised, using collision data from the 2011 LHC run and a dedicated light injection system. For inter-calibration, low mass particle decays ($\\pi^0$ and $\\eta$) to two photons are exploited, as well as the azimuthal symmetry of the average energy deposition at a given pseudorapidity. Absolute calibration has been performed using Z decays into electron-positron pairs. The light injection system monitors the channel response in real-time and enables the re-calibration of the measured energies over time. This is cross-checke...

  15. A new set of calibration standards for estimating the fat and mineral content of vertebrae via dual energy QCT.

    Science.gov (United States)

    Goodsitt, M M; Johnson, R H; Chesnut, C H

    1991-06-01

    A new set of calibration standards has been developed for implementing a dual-energy (DE) quantitative CT technique for estimating the fat and bone content of vertebrae. The QCT technique is based upon a three-component model of bone and utilizes calibration materials that mimic those components in their X-ray attenuation properties. The three components we chose to simulate are bone (mineral plus collagen), fat and a fat-free red marrow. This choice was predicated upon our desire to employ materials that would facilitate later experimental verification of the method. The calibration standards and a set of test samples were manufactured of tissue-simulating epoxy resins. They were employed in studies of the accuracy (consistency) and precision of the technique and in a study of 21 normal postmenopausal women. Estimates of the bone and fat content of the test samples were consistent with the manufacturer's specifications to within 13 mg/ml and 7 vol%, respectively. Long-term reproducibility (coefficient of variation) for both quantities was about 3%. The average bone content of the T12-L3 vertebrae of the human subjects was 262 +/- 32 mg/ml (152 +/- 18 mg/ml calcium hydroxyapatite or mineral) and the average fat content was 63 +/- 8%. Conventional single energy (SE) QCT measurements of these vertebrae were about 23% less than the DE mineral measurements, which is consistent with the differences between SEQCT and ash content that others have determined via chemical analysis. The DE fat content is, in absolute terms, about 15% greater than values reported in the literature and may be due to an error in the assumed composition of red marrow. The true accuracy of the bone and fat estimates is to be determined in a planned human vertebral specimen study.

  16. Calibration of piezoelectric RL shunts with explicit residual mode correction

    DEFF Research Database (Denmark)

    Høgsberg, Jan Becker; Krenk, Steen

    2017-01-01

    Piezoelectric RL (resistive-inductive) shunts are passive resonant devices used for damping of dominant vibration modes of a flexible structure and their efficiency relies on the precise calibration of the shunt components. In the present paper improved calibration accuracy is attained by an exte......Piezoelectric RL (resistive-inductive) shunts are passive resonant devices used for damping of dominant vibration modes of a flexible structure and their efficiency relies on the precise calibration of the shunt components. In the present paper improved calibration accuracy is attained...... by an extension of the local piezoelectric transducer displacement by two additional terms, representing the flexibility and inertia contributions from the residual vibration modes not directly addressed by the shunt damping. This results in an augmented dynamic model for the targeted resonant vibration mode...

  17. Increasing Accuracy in Environmental Measurements

    Science.gov (United States)

    Jacksier, Tracey; Fernandes, Adelino; Matthew, Matt; Lehmann, Horst

    2016-04-01

    Human activity is increasing the concentrations of green house gases (GHG) in the atmosphere which results in temperature increases. High precision is a key requirement of atmospheric measurements to study the global carbon cycle and its effect on climate change. Natural air containing stable isotopes are used in GHG monitoring to calibrate analytical equipment. This presentation will examine the natural air and isotopic mixture preparation process, for both molecular and isotopic concentrations, for a range of components and delta values. The role of precisely characterized source material will be presented. Analysis of individual cylinders within multiple batches will be presented to demonstrate the ability to dynamically fill multiple cylinders containing identical compositions without isotopic fractionation. Additional emphasis will focus on the ability to adjust isotope ratios to more closely bracket sample types without the reliance on combusting naturally occurring materials, thereby improving analytical accuracy.

  18. Targeting LDL Cholesterol: Beyond Absolute Goals Toward Personalized Risk.

    Science.gov (United States)

    Leibowitz, Morton; Cohen-Stavi, Chandra; Basu, Sanjay; Balicer, Ran D

    2017-06-01

    The aim of this study was to review and assess the evidence for low-density lipoprotein cholesterol (LDL-C) treatment goals as presented in current guidelines for primary and secondary prevention of cardiovascular disease. Different sets of guidelines and clinical studies for secondary prevention have centered on lower absolute LDL-C targets [achieve greater reductions in cardiovascular risk. Population-based risk models serve as the basis for statin initiation in primary prevention. Reviews of current population risk models for primary prevention show moderate ability to discriminate [with c-statistics ranging from 0.67 to 0.77 (95% CIs from 0.62 to 0.83) for men and women] with poor calibration and overestimation of risk. Individual clinical trial data are not compelling to support specific LDL-C targets and percent reductions in secondary prevention. Increasing utilization of electronic health records and data analytics will enable the development of individualized treatment goals in both primary and secondary prevention.

  19. Calibration of electrons and photons with the ATLAS detector, and its impact on ATLAS precision measurements

    CERN Document Server

    Becot, C; The ATLAS collaboration

    2014-01-01

    A precise energy calibration of electrons and photons is a key ingredient to many measurements performed with the ATLAS detector, such as the measurement of the Higgs boson mass. An improved calibration scheme is based on corrections derived from collision data, multivariant algorithms for the energy reconstruction and finally electrons from Z boson decays to set the absolute energy scale. Studies of the longitudinal shape of electromagnetic showers also lead to an improved detector material simulation. The calibration is checked with electrons from J/psi decays and photons from radiative photon decays. This contribution will describe the calibration scheme and the cross checks and the impact on ATLAS measurements.

  20. Calibrating the DARHT Electron Spectrometer with Negative Ions

    International Nuclear Information System (INIS)

    R. Trainham , A. P. Tipton , and R. R. Bartech; LAO; LANL)

    2005-01-01

    Negative ions of hydrogen and oxygen have been used to calibrate the DARHT electron spectrometer over the momentum range of 2 to 20 MeV/c. The calibration was performed on September 1, 3, and 8, 2004, and it is good to 0.5% absolute, provided that instrument alignment is carefully controlled. The momentum in MeV/c as a function of magnetic field (B in Gauss) and position in the detector plane (X in mm) is: P = (B-6.28)/(108.404-0.1935*X)