WorldWideScience

Sample records for calibrated reference sources

  1. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a non...

  2. 10 CFR 70.39 - Specific licenses for the manufacture or initial transfer of calibration or reference sources.

    Science.gov (United States)

    2010-01-01

    ... using radiation detection instrumentation capable of detecting 0.005 microcurie of plutonium. If any... calibration or reference source pertinent to evaluation of the potential radiation exposure, including: (i...

  3. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Calibration or reference sources containing americium-241... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of this...

  4. Calibrated vapor generator source

    Science.gov (United States)

    Davies, J.P.; Larson, R.A.; Goodrich, L.D.; Hall, H.J.; Stoddard, B.D.; Davis, S.G.; Kaser, T.G.; Conrad, F.J.

    1995-09-26

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet. 10 figs.

  5. Calibration of Photon Sources for Brachytherapy

    Science.gov (United States)

    Rijnders, Alex

    Source calibration has to be considered an essential part of the quality assurance program in a brachytherapy department. Not only it will ensure that the source strength value used for dose calculation agrees within some predetermined limits to the value stated on the source certificate, but also it will ensure traceability to international standards. At present calibration is most often still given in terms of reference air kerma rate, although calibration in terms of absorbed dose to water would be closer to the users interest. It can be expected that in a near future several standard laboratories will be able to offer this latter service, and dosimetry protocols will have to be adapted in this way. In-air measurement using ionization chambers (e.g. a Baldwin—Farmer ionization chamber for 192Ir high dose rate HDR or pulsed dose rate PDR sources) is still considered the method of choice for high energy source calibration, but because of their ease of use and reliability well type chambers are becoming more popular and are nowadays often recommended as the standard equipment. For low energy sources well type chambers are in practice the only equipment available for calibration. Care should be taken that the chamber is calibrated at the standard laboratory for the same source type and model as used in the clinic, and using the same measurement conditions and setup. Several standard laboratories have difficulties to provide these calibration facilities, especially for the low energy seed sources (125I and 103Pd). Should a user not be able to obtain properly calibrated equipment to verify the brachytherapy sources used in his department, then at least for sources that are replaced on a regular basis, a consistency check program should be set up to ensure a minimal level of quality control before these sources are used for patient treatment.

  6. 10 CFR 32.102 - Schedule C-prototype tests for calibration or reference sources containing americium-241 or...

    Science.gov (United States)

    2010-01-01

    ... sources containing americium-241 or radium-226. 32.102 Section 32.102 Energy NUCLEAR REGULATORY COMMISSION... americium-241 or radium-226. An applicant for a license under § 32.57 shall, for any type of source which is designed to contain more than 0.185 kilobecquerel (0.005 microcurie) of americium-241 or radium-226...

  7. Evaluation of the homogeneity of reference flat sources used in calibration of surface contamination monitors; Avaliacao da homogeneidade das fontes planas de referencia utilizadas na calibracao de monitores de contaminacao de superficie

    Energy Technology Data Exchange (ETDEWEB)

    Silva Junior, I.A.; Xavier, M.; Siqueira, P.T.D.; Potiens, M.P.A., E-mail: iremarjr@ipen.br, E-mail: mxavier@ipen.br, E-mail: ptsiquei@ipen.br, E-mail: mppalbu@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2014-07-01

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

  8. RF Reference Switch for Spaceflight Radiometer Calibration

    Science.gov (United States)

    Knuble, Joseph

    2013-01-01

    The goal of this technology is to provide improved calibration and measurement sensitivity to the Soil Moisture Active Passive Mission (SMAP) radiometer. While RF switches have been used in the past to calibrate microwave radiometers, the switch used on SMAP employs several techniques uniquely tailored to the instrument requirements and passive remote-sensing in general to improve radiometer performance. Measurement error and sensitivity are improved by employing techniques to reduce thermal gradients within the device, reduce insertion loss during antenna observations, increase insertion loss temporal stability, and increase rejection of radar and RFI (radio-frequency interference) signals during calibration. The two legs of the single-pole double-throw reference switch employ three PIN diodes per leg in a parallel-shunt configuration to minimize insertion loss and increase stability while exceeding rejection requirements at 1,413 MHz. The high-speed packaged diodes are selected to minimize junction capacitance and resistance while ensuring the parallel devices have very similar I-V curves. Switch rejection is improved by adding high-impedance quarter-wave tapers before and after the diodes, along with replacing the ground via of one diode per leg with an open circuit stub. Errors due to thermal gradients in the switch are reduced by embedding the 50-ohm reference load within the switch, along with using a 0.25-in. (approximately equal to 0.6-cm) aluminum prebacked substrate. Previous spaceflight microwave radiometers did not embed the reference load and thermocouple directly within the calibration switch. In doing so, the SMAP switch reduces error caused by thermal gradients between the load and switch. Thermal issues are further reduced by moving the custom, highspeed regulated driver circuit to a physically separate PWB (printed wiring board). Regarding RF performance, previous spaceflight reference switches have not employed high-impedance tapers to improve

  9. CLARREO/RSIS Reference Inter-Calibration Ability and Requirements

    Science.gov (United States)

    Lukashin, C.; Macdonnell, D.; Roithmayr, C.; Speth, P.; Wielicki, B.

    2009-12-01

    The CLARREO Reflected Shortwave Imaging Spectrometer (RSIS) is designed to provide an SI traceable in-orbit calibration standard with absolute accuracy of 0.3% (2 sigma) over the mission lifetime. The the goal of inter-calibration is to enable rigorous decadal change observations of critical climate change components including reflected broadband radiation (CERES), decadal change in cloud properties (VIIRS/MODIS/AVHRR), surface albedo changes including snow and ice albedo feedback. The CLARREO/RSIS approach for inter-calibration is to use the highly accurate spectral reflectance and reflected radiances to establish in orbit reference for existing Earth viewing reflected solar radiation sensors: CERES and VIIRS on NPP and NPOESS satellites, as well as AVHRR and follow-on imagers on METOP. The mission goal is to be able to provide sufficient numbers of space/time/angle matched opportunities of these instruments with the CLARREO/RSIS reference measurements to overcome the random error sources from imperfect data matching and instrument noise. The inter-calibration method is to monitor over time changes in targeted sensor response functions: effective offset, gain, non-linearity, spectral response function and sensitivity to polarization of optics. In this study we used existing satellite data (CERES, PARASOL) and simulation methods to determine requirements for CLAREO/RSIS inter-calibration sampling and data matching.

  10. MSSC: Multi-Source Self-Calibration

    Science.gov (United States)

    Radcliffe, Jack F.

    2017-09-01

    Multi-Source Self-Calibration (MSSC) provides direction-dependent calibration to standard phase referencing. The code combines multiple faint sources detected within the primary beam to derive phase corrections. Each source has its CLEAN model divided into the visibilities which results in multiple point sources that are stacked in the uv plane to increase the S/N, thus permitting self-calibration. This process applies only to wide-field VLBI data sets that detect and image multiple sources within one epoch.

  11. Terrestrial reference standard sites for postlaunch sensor calibration

    Science.gov (United States)

    Teillet, P.M.; Chander, G.

    2010-01-01

    In an era when the number of Earth observation satellites is rapidly growing and measurements from satellite sensors are used to address increasingly urgent global issues, often through synergistic and operational combinations of data from multiple sources, it is imperative that scientists and decision-makers are able to rely on the accuracy of Earth observation data products. The characterization and calibration of these sensors, particularly their relative biases, are vital to the success of the developing integrated Global Earth Observation System of Systems (GEOSS) for coordinated and sustained observations of the Earth. This can only reliably be achieved in the postlaunch environment through the careful use of observations by multiple sensor systems over common, well-characterized terrestrial targets (i.e., on or near the Earth's surface). Through greater access to and understanding of these vital reference standard sites and their use, the validity and utility of information gained from Earth remote sensing will continue to improve. This paper provides a brief overview of the use of reference standard sites for postlaunch sensor radiometric calibration from historical, current, and future perspectives. Emphasis is placed on optical sensors operating in the visible, near-infrared, and shortwave infrared spectral regions.

  12. Calibration of reference KAP-meters at SSDL and cross calibration of clinical KAP-meters.

    Science.gov (United States)

    Hetland, Per O; Friberg, Eva G; Ovrebø, Kirsti M; Bjerke, Hans H

    2009-01-01

    In the summer of 2007 the secondary standard dosimetry laboratory (SSDL) in Norway established a calibration service for reference air-kerma product meter (KAP-meter). The air-kerma area product, P(KA), is a dosimetric quantity that can be directly related to the patient dose and used for risk assessment associated with different x-ray examinations. The calibration of reference KAP-meters at the SSDL gives important information on parameters influencing the calibration factor for different types of KAP-meters. The use of reference KAP-meters calibrated at the SSDL is an easy and reliable way to calibrate or verify the P(KA) indicated by the x-ray equipment out in the clinics. Twelve KAP-meters were calibrated at the SSDL by use of the substitution method at five diagnostic radiation qualities (RQRs). The calibration factors varied from 0.94 to 1.18. The energy response of the individual KAP-meters varied by a total of 20% between the different RQRs and the typical chamber transmission factors ranged from 0.78 to 0.91. It is important to use a calibrated reference KAP-meter and a harmonised calibration method in the P(KA) calibration in hospitals. The obtained uncertainty in the P(KA) readings is comparable with other calibration methods if the information in the calibration certificate is correct used, corrections are made and proper positioning of the KAP-chamber is performed. This will ensure a reliable estimate of the patient dose and a proper optimisation of conventional x-ray examinations and interventional procedures.

  13. American Folklore: A Guide to Reference Sources.

    Science.gov (United States)

    Kibbee, Jo

    1989-01-01

    This annotated bibliography represents a core collection of reference sources on American folklore. In addition to general references, genre specific reference sources are listed in the following areas: folk narrative; folk music; customary folklore; material culture; ethnic and regional bibliographies; and applied folklore. (39 references) (CLB)

  14. Physical Education Research Reference Sources.

    Science.gov (United States)

    Kissinger, Pat, Comp.

    This guide on physical education research reference resources was compiled for the use of physical education students and teachers. While it was written to be used by Northern Illinois University library users, much information may be useful to all physical education students who would be doing research using standard basic reference sources…

  15. Comparison of Blackbody Sources for Low-Temperature IR Calibration

    Science.gov (United States)

    Ljungblad, S.; Holmsten, M.; Josefson, L. E.; Klason, P.

    2015-12-01

    Radiation thermometers are traditionally mostly used in high-temperature applications. They are, however, becoming more common in different applications at room temperature or below, in applications such as monitoring frozen food and evaluating heat leakage in buildings. To measure temperature accurately with a pyrometer, calibration is essential. A problem with traditional, commercially available, blackbody sources is that ice is often formed on the surface when measuring temperatures below 0°C. This is due to the humidity of the surrounding air and, as ice does not have the same emissivity as the blackbody source, it biases the measurements. An alternative to a traditional blackbody source has been tested by SP Technical Research Institute of Sweden. The objective is to find a cost-efficient method of calibrating pyrometers by comparison at the level of accuracy required for the intended use. A disc-shaped blackbody with a surface pyramid pattern is placed in a climatic chamber with an opening for field of view of the pyrometer. The temperature of the climatic chamber is measured with two platinum resistance thermometers in the air in the vicinity of the disc. As a rule, frost will form only if the deposition surface is colder than the surrounding air, and, as this is not the case when the air of the climatic chamber is cooled, there should be no frost or ice formed on the blackbody surface. To test the disc-shaped blackbody source, a blackbody cavity immersed in a conventional stirred liquid bath was used as a reference blackbody source. Two different pyrometers were calibrated by comparison using the two different blackbody sources, and the results were compared. The results of the measurements show that the disc works as intended and is suitable as a blackbody radiation source.

  16. Reference Sources for Folklore Studies.

    Science.gov (United States)

    Pilling, George, Comp.

    An annotated listing contains 35 basic reference materials on folklore. Following a discussion of the definition of folklore, citations are divided into the following categories: encyclopedias and dictionaries, national and regional encyclopedias and dictionaries, bibliographies, guides, indexes, and periodicals. The Library of Congress…

  17. Govt. Pubs.: NTIS Reference Sources.

    Science.gov (United States)

    Korman, Richard; Aluri, Rao

    1980-01-01

    Cites review sources for NTIS (National Technical Information Service) publications and provides an annotated list of 22 reports on child abuse, Chinese language romanization, criminal justice, energy, environment, ethnic data, fire technology, genealogy, health care, local communities and federal assistance, mainstreaming, political leadership in…

  18. Anthropology: Guide to Reference Sources.

    Science.gov (United States)

    Mason, Mary G., Ed.

    More than 80 anthropology source materials concentrating on cultural and social anthropology are cited in this annotated bibliography. Materials, located in the McLennan Library at McGill University (Montreal), are listed according to type of material. Library of Congress call numbers are presented; dates of publication range from 1950 to 1985.…

  19. Development of a quality assured calibration method for the PSI radon chamber reference atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Schuler, C.; Butterweck-Dempewolf, G.; Vezzu, G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-08-01

    Radon detectors and measuring instruments are calibrated at the PSI Reference Laboratory for Radon Gas Concentration Measurements by exposing them to a calibrated radon reference atmosphere in the PSI radon chamber. A sophisticated and quality assured calibration technique was developed which guarantees the traceability of this radon chamber reference atmosphere to standards of internationally acknowledged primary laboratories. (author) 2 figs., 2 refs.

  20. Russian History; A Guide to Reference Sources.

    Science.gov (United States)

    McGill Univ., Montreal (Quebec). McLennan Library.

    This guide identifies reference sources for the study of Russian and Soviet history available in the McGill University (Montreal) McLennan Library. Russian, English, French, and German language works covering Russian history from its origins to World War II are included. The guide is arranged in two parts: general reference sources and…

  1. Environmental Sciences Reference Sources. An Annotated Bibliography.

    Science.gov (United States)

    McMartin, Mary I., Comp.

    This list of Environmental Sciences References Sources is intended to give undergraduate and graduate students a starting point when searching for information in the library. Entries are grouped according to type of reference material and then are listed in alphabetical order. The types of reference material included are guides to dictionaries,…

  2. 10 CFR 35.432 - Calibration measurements of brachytherapy sources.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Calibration measurements of brachytherapy sources. 35.432 Section 35.432 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Manual Brachytherapy § 35.432 Calibration measurements of brachytherapy sources. (a) Before the first medical use of a...

  3. Calibration procedure of Hukseflux SR25 to Establish the Diffuse Reference for the Outdoor Broadband Radiometer Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Reda, Ibrahim M. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Andreas, Afshin M. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-08-01

    Accurate pyranometer calibrations, traceable to internationally recognized standards, are critical for solar irradiance measurements. One calibration method is the component summation method, where the pyranometers are calibrated outdoors under clear sky conditions, and the reference global solar irradiance is calculated as the sum of two reference components, the diffuse horizontal and subtended beam solar irradiances. The beam component is measured with pyrheliometers traceable to the World Radiometric Reference, while there is no internationally recognized reference for the diffuse component. In the absence of such a reference, we present a method to consistently calibrate pyranometers for measuring the diffuse component. The method is based on using a modified shade/unshade method and a pyranometer with less than 0.5 W/m2 thermal offset. The calibration result shows that the responsivity of Hukseflux SR25 pyranometer equals 10.98 uV/(W/m2) with +/-0.86 percent uncertainty.

  4. Numerical design and testing of a sound source for secondary calibration of microphones using the Boundary Element Method

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Juhl, Peter Møller; Barrera Figueroa, Salvador

    2009-01-01

    Secondary calibration of microphones in free field is performed by placing the microphone under calibration in an anechoic chamber with a sound source, and exposing it to a controlled sound field. A calibrated microphone is also measured as a reference. While the two measurements are usually made...

  5. Measuring Source Code Similarity Using Reference Vectors

    Science.gov (United States)

    Ohno, Asako; Murao, Hajime

    In this paper, we propose a novel method to measure similarity between program source codes. Different to others, our method doues not compare two source codes directly but compares two reference vectors, where a reference vector is calculated from one source code and a set of reference source codes. This means that our method requires no original source code when considering an application open to public such as a search engine for the program source code on the internet. We have built a simple search system and have evaluated with Java source codes made in the university course of basic programming. Results show that the system can achieve quite high average precision rate in very short time which means the proposed method can measure correct similarity very fast.

  6. Information Entrepreneurship: Sources for Reference Librarians.

    Science.gov (United States)

    Gilton, Donna L.

    1992-01-01

    Discusses information entrepreneurs, or information brokers, and information intrapreneurship, or the establishment of fee-based information services within a library. Annotations are provided for 56 information sources that include general materials, research in these areas, and relationships with traditional reference services. (four references)…

  7. A new irradiated quartz for beta source calibration

    DEFF Research Database (Denmark)

    Hansen, Vicki; Murray, Andrew Sean; Buylaert, Jan-Pieter

    2015-01-01

    laboratories have used the various different batches of Risø calibration quartz for the calibration of beta and X-ray sources, but these have been largely undescribed. Here we describe in detail the preparation and luminescence characteristics of a new quartz standard, based on a North Sea beach sand collected...

  8. Dosimetric calibration of solid state detectors with low energy {beta} sources

    Energy Technology Data Exchange (ETDEWEB)

    Fidanzio, Andrea [Istituto di Fisica, Universita Cattolica del Sacro Cuore, Rome (Italy)], E-mail: andrea.fidanzio@rm.unicatt.it; Pia Toni, Maria [Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti (ENEA), Rome (Italy); Capote, Roberto; Pena, Juan [Departmento FAMN, Universidad de Sevilla, Facultad de Fisica, AP 1065, Sevilla 41080 (Spain); Centro de Estudios Aplicados al Desarrollo Nuclear, AP 100, La Habana 11300 (Cuba); Pasciuti, Katia [Istituto di Fisica, Universita Cattolica del Sacro Cuore, Rome (Italy); Bovi, Maurizio [Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti (ENEA), Rome (Italy); Perrone, Franco [U.O. di Fisica Sanitaria, Spedali Civili Santa Chiara, Pisa (Italy); Azario, Luigi [Istituto di Fisica, Universita Cattolica del Sacro Cuore, Rome (Italy); Lazzeri, Mauro [U.O. di Fisica Sanitaria, Spedali Civili Santa Chiara, Pisa (Italy); Gaudino, Diego [Istituto di Fisica, Universita Cattolica del Sacro Cuore, Rome (Italy); Piermattei, Angelo [Istituto di Fisica, Universita Cattolica del Sacro Cuore, Rome (Italy); U.O. di Fisica Sanitaria, Centro di Ricerca e Formazione ad Alta Tecnologia nelle Scienze Biomediche dell' Universita Cattolica Sacro Cuore, Campobasso (Italy)

    2008-01-15

    A PTW Optidos plastic scintillation and a PTW natural diamond detectors were calibrated in terms of absorbed dose to water with {beta} fields produced by {sup 90}Sr + {sup 90}Y and {sup 85}Kr reference sources. Each source was characterized at the Italian National Metrological Institute - the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of ENEA (ENEA-INMRI) - for two different series, 1 and 2, of ISO reference {beta}-particle radiation fields. Beam flattening filters were used for the series 1 {beta} fields to give uniform absorbed dose rates over a large area at a source-to-reference plane distance of 30 cm. The series 2 {beta} fields were produced at source-to-reference plane distance of 10 cm, without the beam flattening filters, in order to obtain higher absorbed dose rates. The reference absorbed dose rate values were directly determined by the Italian national standard for {beta}-particle dosimetry (a PTW extrapolation ionization chamber) for the series 1 {beta} fields and by a calibrated transfer standard chamber, (a Capintec thin fixed-volume parallel plate ionization chamber) for the series 2 {beta} fields. Finally the two solid state detectors were calibrated in terms of absorbed dose to water with the series 2 {beta} field. The expanded uncertainties of the calibration coefficients obtained for the plastic scintillation dosimeter were 10% and 12% (2SD) for the {sup 90}Sr + {sup 90}Y and the {sup 85}Kr sources, respectively. The expanded uncertainties obtained for the diamond dosimeter were 10% (2SD) and 16% (2SD) for the {sup 90}Sr + {sup 90}Y and the {sup 85}Kr sources, respectively. The good results obtained with the {sup 90}Sr + {sup 90}Y and the {sup 85}Kr {beta} sources encourage to implement this procedure to calibrate this type of detectors at shorter distances and with other {beta} sources of interest in brachytherapy, for example the {sup 106}Ru source.

  9. 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.

  10. A calibration method for photon counters using a customized standard light source

    Science.gov (United States)

    Lin, Shulang; Gu, Huarong; Tan, Qiaofeng

    2016-10-01

    Photomultiplier tubes (PMTs) are the most common photoelectric conversion apparatus used as photon counters. Because of the sensitivity of the PMTs to the interference, calibration is necessary during the application of the PMTs. Traditional solutions for calibration are either based on the inverse square law of illumination, or using light-emitting diodes (LEDs) as standard light sources. However, rigid experimental techniques are required for these solutions. And the emission spectrum of LEDs does not cover the entire spectrum of detection. In this paper, a calibration method is presented by using a customized standard light source which can provide full spectrum of weak light from the dark count level to the saturation level of the PMTs. The photon counter in a light-shielding cavity is connected, via an optical fiber, to the customized standard light source attached with an intensity detector. The calibration process is discussed and experimental results with chemical reference substance are also presented for comparison.

  11. Interlaboratory beta source calibration using TL and OSL on natural quartz

    DEFF Research Database (Denmark)

    Goksu. H.Y.; Bailiff, I.K.; Bøtter-Jensen, L.

    1995-01-01

    Laboratories using luminescence methods for dose reconstruction have to make interlaboratory source calibrations-initially this will be a single isotope beta or gamma source using one particular reference material. The procedure requires not only the administration of exact doses to the material...... Laboratory at GSF using a Go-60 source as well as the in situ measurements with an ionization chamber, calibrated to the primary standards of PTB Braunschweig. Irradiated and unirradiated quartz was distributed to the five laboratories and although different procedures were used for thermoluminescence...

  12. 10 CFR 851.27 - Reference sources.

    Science.gov (United States)

    2010-01-01

    ... OF ENERGY WORKER SAFETY AND HEALTH PROGRAM Specific Program Requirements § 851.27 Reference sources.... Department of Energy, Office of Health, Safety and Security, Forrestal Building, 1000 Independence Ave., SW...). (2) ANSI Z136.1, “Safe Use of Lasers,” (2000). (3) ANSI Z49.1, “Safety in Welding, Cutting and Allied...

  13. Anthropology: A Student's Guide to Reference Sources.

    Science.gov (United States)

    Slavin, Suzy M., Comp.

    The guide identifies approximately 100 anthropology source materials in the reference department of McLennan Library at McGill University. It was designd to help students doing anthropological research and to illustrate the variety of materials on social and cultural anthropology in the McLennan Library. Physical anthropolgy, linguistics, and…

  14. Acceptance test of an activity meter to be used as reference in a calibration methodology establishment

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Eduardo L.; Kuahara, Lilian T.; Potiens, Maria da Penha A., E-mail: educorrea1905@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2014-07-01

    The nuclear medicine is a medical physics area in which radiopharmaceuticals are used in diagnostic procedures. These radioactive elements are administered in the patient and the radiation emitted is detected by an equipment, that makes the body scan, connected to a computer software, and the image is constructed. In order to operate the nuclear medicine service must have calibrated radiation detectors. Thought, it does not exist, in Brazil, an activity meter calibration methodology, which causes many measurement uncertainties. The goal of this study is to present the acceptance test results of an activity meter to be used as reference in a new calibration methodology establishment. It was checked an activity meter Capintec, CRC-25R model, using three control sources ({sup 137}Cs, {sup 57}Co, {sup 133}Ba). The tests were based on the CNEN-NN 3.05 standard, the manufacturer manual, the TRS-454 and the TECDOC 602 and include: physical inspection, chamber voltage, zero adjustment, background response, data check and repeatability. The linearity and geometry tests could not be made, because the laboratory where the activity meter is located is not authorized to receive non-sealed radioactive sources. The equipment has presented a good behavior. All the results are in the range presented by national and international standards and the equipment is now being used in the laboratory and periodically passes through the quality control tests. (author)

  15. 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...

  16. A calibrated source of N 2O 5

    Science.gov (United States)

    Fahey, D. W.; Eubank, C. S.; Hübler, G.; Fehsenfeld, F. C.

    A calibrated source of N 2O 5 was developed for use in evaluating instruments designed to measure reactive odd-nitrogen species in the atmosphere. The desirable features of the source are the output of a very low mixing ratio of N 2O 5, the measurement of total reactive nitrogen NO y in the source output, and the use of commercially-available detection and calibration equipment. N 2O 5 was derived from a solid crystalline sample at 192 K. Mixing ratios of N 2O 5 less than 2 ppmv (parts per million by volume) were produced in a small flow ( parts per billion by volume) in flows greater than 1 STPℓ min -1. The N 2O 5 mixing ratio was determined with an accuracy of ± 15 % by using a thermal dissociator, calibrated NO/N 2 mixtures, and an NO chemiluminescence detector. The level of other reactive nitrogen species in the source output was determined with an Au catalytic converter and the NO detector.

  17. Camera self-calibration from translation by referring to a known camera.

    Science.gov (United States)

    Zhao, Bin; Hu, Zhaozheng

    2015-09-01

    This paper presents a novel linear method for camera self-calibration by referring to a known (or calibrated) camera. The method requires at least three images, with two images generated by the uncalibrated camera from pure translation and one image generated by the known reference camera. We first propose a method to compute the infinite homography from scene depths. Based on this, we use two images generated by translating the uncalibrated camera to recover scene depths, which are further utilized to linearly compute the infinite homography between an arbitrary uncalibrated image, and the image from the known camera. With the known camera as reference, the computed infinite homography is readily decomposed for camera calibration. The proposed self-calibration method has been tested with simulation and real image data. Experimental results demonstrate that the method is practical and accurate. This paper proposes using a "known reference camera" for camera calibration. The pure translation, as required in the method, is much more maneuverable, compared with some strict motions in the literature, such as pure rotation. The proposed self-calibration method has good potential for solving online camera calibration problems, which has important applications, especially for multicamera and zooming camera systems.

  18. Source point calibration from an arbitrary electron backscattering pattern

    DEFF Research Database (Denmark)

    Lassen, Niels Christian Krieger

    1999-01-01

    Precise knowledge of the position of the source point is a requirement if electron backscattering patterns (EBSPs) are to be used for crystal orientation measurements or other types of measurements which demand a geometrical analysis of the patterns. Today, possibly the most popular method...... for locating the source point is a computational technique which uses the positions of a number of indexed Kikuchi bands for calculating the coordinates of the point. A serious limitation of this calibration technique is, however, that the localized bands must first be indexed, which is difficult...... by this new calibration procedure is the same crystallographic information which is used for normal indexing of EBSPs. The procedure is shown to work successfully with patterns from a simple cubic crystal, as well as with patterns from an orthorhombic BiSCCO superconductor. In the former case, four bands...

  19. The VTTVIS line imaging spectrometer - principles, error sources, and calibration

    DEFF Research Database (Denmark)

    Jørgensen, R.N.

    2002-01-01

    work describing the basic principles, potential error sources, and/or adjustment and calibration procedures. This report fulfils the need for such documentationwith special focus on the system at KVL. The PGP based system has several severe error sources, which should be removed prior any analysis....... Most of the random noise sources can be minimised by carefully selecting high-grade components especially withconcern to the camera. Systematic error sources like CCD fixed pattern noise (FPN), CCD photoresponse nonuniformity (PRNU), CCD charge transfer efficiency (CTE), slit width variations, changes...... in off-axis transmission efficiencies, diffractionefficiencies, and image distortion have a significant impact on the instrument performance. Procedures removing or minimising these systematic error sources are developed and described for the system build at KVL but can be generalised to other PGP...

  20. Calibration of Radiation Thermometers up to : Effective Emissivity of the Source

    Science.gov (United States)

    Kozlova, O.; Briaudeau, S.; Rongione, L.; Bourson, F.; Guimier, S.; Kosmalski, S.; Sadli, M.

    2015-08-01

    The growing demand of industry for traceable temperature measurements up to encourages improvement of calibration techniques for industrial-type radiation thermometers in this temperature range. High-temperature fixed points can be used at such high temperatures, but due to the small diameter of apertures of their cavities (3 mm), they are not adapted for the large field-of-views commonly featured by this kind of radiation thermometers. At LNE-Cnam, a Thermo Gauge furnace of 25.4 mm source aperture diameter is used as a comparison source to calibrate customers' instruments against a reference radiation thermometer calibrated according to the ITS-90 with the lowest uncertainties achievable in the Laboratory. But the furnace blackbody radiator exhibits a large temperature gradient that degrades its effective emissivity, and increases the calibration uncertainty due to the lack of information on the working spectral band of the industrial radiation thermometer. In order to estimate the corrections to apply, the temperature distribution (radial and on-axis) of the Thermo Gauge furnace blackbody radiator was characterized and the effective emissivity of the Thermo Gauge cavity was determined by three different methods. Because of this investigation, the corrections due to different fields of view and due to the different spectral bands of the reference pyrometer and the customer's pyrometer were obtained and the uncertainties on these corrections were evaluated.

  1. Use of Naturally Available Reference Targets to Calibrate Airborne Laser Scanning Intensity Data

    Directory of Open Access Journals (Sweden)

    Paula Litkey

    2009-04-01

    Full Text Available We have studied the possibility of calibrating airborne laser scanning (ALS intensity data, using land targets typically available in urban areas. For this purpose, a test area around Espoonlahti Harbor, Espoo, Finland, for which a long time series of ALS campaigns is available, was selected. Different target samples (beach sand, concrete, asphalt, different types of gravel were collected and measured in the laboratory. Using tarps, which have certain backscattering properties, the natural samples were calibrated and studied, taking into account the atmospheric effect, incidence angle and flying height. Using data from different flights and altitudes, a time series for the natural samples was generated. Studying the stability of the samples, we could obtain information on the most ideal types of natural targets for ALS radiometric calibration. Using the selected natural samples as reference, the ALS points of typical land targets were calibrated again and examined. Results showed the need for more accurate ground reference data, before using natural samples in ALS intensity data calibration. Also, the NIR camera-based field system was used for collecting ground reference data. This system proved to be a good means for collecting in situ reference data, especially for targets with inhomogeneous surface reflection properties.

  2. Study and mitigation of calibration error sources in a water vapour Raman lidar

    Science.gov (United States)

    David, Leslie; Bock, Olivier; Bosser, Pierre; Thom, Christian; Pelon, Jacques

    2014-05-01

    The monitoring of water vapour throughout the atmosphere is important for many scientific applications (weather forecasting, climate research, calibration of GNSS altimetry measurements). Measuring water vapour remains a technical challenge because of its high variability in space and time. The major issues are achieving long-term stability (e.g., for climate trends monitoring) and high accuracy (e.g. for calibration/validation applications). LAREG and LOEMI at Institut National de l'Information Géographique et Forestière (IGN) have developed a mobile scanning water vapour Raman lidar in collaboration with LATMOS at CNRS. This system aims at providing high accuracy water vapour measurements throughout the troposphere for calibrating GNSS wet delay signals and thus improving vertical positioning. Current developments aim at improving the calibration method and long term stability of the system to allow the Raman lidar to be used as a reference instrument. The IGN-LATMOS lidar was deployed in the DEMEVAP (Development of Methodologies for Water Vapour Measurement) campaign that took place in 2011 at the Observatoire de Haute Provence. The goals of DEMEVAP were to inter-compare different water vapour sounding techniques (lidars, operational and research radiosondes, GPS,…) and to study various calibration methods for the Raman lidar. A significant decrease of the signals and of the calibration constants of the IGN-LATMOS Raman lidar has been noticed all along the campaign. This led us to study the likely sources of uncertainty and drifts in each part of the instrument: emission, reception and detection. We inventoried several error sources as well as instability sources. The impact of the temperature dependence of the Raman lines on the filter transmission or the fluorescence in the fibre, are examples of the error sources. We investigated each error source and each instability source (uncontrolled laser beam jitter, temporal fluctuations of the photomultiplier

  3. Calibration of Nu-Instruments Noblesse multicollector mass spectrometers for argon isotopic measurements using a newly developed reference gas

    Science.gov (United States)

    Coble, M.A.; Grove, M.; Calvert, A.T.

    2011-01-01

    The greatest challenge limiting 40Ar/39Ar multicollection measurements is the availability of appropriate standard gasses to intercalibrate detectors. In particular, use of zoom lens ion-optics to steer and focus ion beams into a fixed detector array (i.e., Nu Instruments Noblesse) makes intercalibration of multiple detectors challenging because different ion-optic tuning conditions are required for optimal peak shape and sensitivity at different mass stations. We have found that detector efficiency and mass discrimination are affected by changes in ion-optic tuning parameters. Reliance upon an atmospheric Ar standard to calibrate the Noblesse is problematic because there is no straightforward way to relate atmospheric 40Ar and 36Ar to measurements of 40Ar and 39Ar if they are measured on separate detectors. After exploring alternative calibration approaches, we have concluded that calibration of the Noblesse is best performed using exactly the same source, detector, and ion-optic tuning settings as those used in routine 40Ar/39Ar analysis. To accomplish this, we have developed synthetic reference gasses containing 40Ar, 39Ar and 38Ar produced by mixing gasses derived from neutron-irradiated sanidine with an enriched 38Ar spike. We present a new method for calibrating the Noblesse based on use of both atmospheric Ar and the synthetic reference gasses. By combining atmospheric Ar and synthetic reference gas in different ways, we can directly measure 40Ar/39Ar, 38Ar/39Ar, and 36Ar/39Ar correction factors over ratios that vary from 0.5 to 460. These correction factors are reproducible to better than ??0.5??? (2?? standard error) over intervals spanning ~24h but can vary systematically by ~4% over 2weeks of continuous use when electron multiplier settings are held constant. Monitoring this variation requires daily calibration of the instrument. Application of the calibration method to 40Ar/39Ar multicollection measurements of widely used sanidine reference materials

  4. Programmable and automatic calibrator for radio sources at 45 MHz

    Science.gov (United States)

    Aparici, J.; May, J.; Salas, F.; Ventura, J.

    1981-12-01

    The design, construction and operation of a standard calibrator is presented. The calibrator consists of saturated diodes controlled by an indirect feed-back system and a digital-to-analog converter. The advantages over similar designs are described, as for instance, high-resolution in the calibration scale, good stability, very fast calibrations, use of balanced electronic switches, etc.

  5. Awareness and perception of reference sources and services by ...

    African Journals Online (AJOL)

    ... e-mail, telephone and social media (e.g. facebook). It was also revealed that 228 (70.45%) have good knowledge of what reference source are; 192 (59.08%) have good understanding of what reference services are, and 241 (74.15%) make use of reference sources in the Federal University of Technology, Owerri library.

  6. Results of the PEP`93 intercomparison of reference cell calibrations and newer technology performance measurements

    Energy Technology Data Exchange (ETDEWEB)

    Osterwald, C.R.; Emery, K. [National Renewable Energy Lab., Golden, CO (United States); Anevsky, S. [All-Union Research Inst. for Optophysical Measurements, Moscow (Russian Federation)] [and others

    1996-05-01

    This paper presents the results of an international intercomparison of photovoltaic (PV) performance measurements and calibrations. The intercomparison, which was organized and operated by a group of experts representing national laboratories from across the globe (i.e., the authors of this paper), was accomplished by circulating two sample sets. One set consisted of twenty silicon reference cells that would, hopefully, form the basis of an international PV reference scale. A qualification procedure applied to the calibration results gave average calibration numbers with an overall standard deviation of less than 2% for the entire set. The second set was assembled from a wide range of newer technologies that present unique problems for PV measurements. As might be expected, these results showed much larger differences among laboratories. Methods were then identified that should be used to measure such devices, along with problems to avoid.

  7. Temperature compensated and self-calibrated current sensor using reference magnetic field

    Science.gov (United States)

    Yakymyshyn, Christopher Paul; Brubaker, Michael Allen; Yakymyshyn, Pamela Jane

    2007-10-09

    A method is described to provide temperature compensation and self-calibration of a current sensor based on a plurality of magnetic field sensors positioned around a current carrying conductor. A reference magnetic field generated within the current sensor housing is detected by the magnetic field sensors and is used to correct variations in the output signal due to temperature variations and aging.

  8. Temperature compensated and self-calibrated current sensor using reference current

    Science.gov (United States)

    Yakymyshyn, Christopher Paul [Seminole, FL; Brubaker, Michael Allen [Loveland, CO; Yakymyshyn, Pamela Jane [Seminole, FL

    2008-01-22

    A method is described to provide temperature compensation and self-calibration of a current sensor based on a plurality of magnetic field sensors positioned around a current carrying conductor. A reference electrical current carried by a conductor positioned within the sensing window of the current sensor is used to correct variations in the output signal due to temperature variations and aging.

  9. 10 CFR 35.2432 - Records of calibration measurements of brachytherapy sources.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Records of calibration measurements of brachytherapy... Records § 35.2432 Records of calibration measurements of brachytherapy sources. (a) A licensee shall maintain a record of the calibrations of brachytherapy sources required by § 35.432 for 3 years after the...

  10. 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

  11. Factors affecting quality for beta dose rate measurements using ISO 6980 series I reference sources

    Energy Technology Data Exchange (ETDEWEB)

    Burns, R.E. Jr.; O`Brien, J.M. Jr. [Atlan-Tech, Rosewll, GA (United States)

    1993-12-31

    Atlan-Tech, Inc. has performed several calibrations of ISO 6980 Series 1 reference beta sources over the past two to three years. There were many problems encountered in attempting to compare the results of these calibrations with those from other laboratories, indicating the need for more standardization in the methodology employed for the measurement of the absorbed dose rate from ISO 6980 Series 1 reference beta sources. This document describes some of the problems encountered in attempting to intercompare results of beta dose-rate measurements. It proposes some solutions in an attempt to open a dialogue among facilities using reference beta standards for the purpose of promoting better measurement quality assurance through data intercomparison.

  12. Folklore: A Guide to Reference Sources.

    Science.gov (United States)

    Slavin, Suzy, Comp.

    This biliography, designed primarily for students of literature and anthropology, deals principally with traditional oral folk literature and the folk tale narrative. The materials in the bibliography, cited for their references to folk arts, crafts, customs, legends, and riddles, are listed within four categories: guides and handbooks,…

  13. Calibration of a multi-beam Laser System by using a TLS-generated Reference

    Directory of Open Access Journals (Sweden)

    M. Gordon

    2013-10-01

    Full Text Available Rotating multi-beam LIDARs mounted on moving platforms have become very successful for many applications such as autonomous navigation, obstacle avoidance or mobile mapping. To obtain accurate point coordinates, a precise calibration of such a LIDAR system is required. For the determination of the corresponding parameters we propose a calibration scheme which exploits the information of 3D reference point clouds captured by a terrestrial laser scanning (TLS device. It is assumed that the accuracy of this point clouds is considerably higher than that from the multi-beam LIDAR and that the data represent faces of man-made objects at different distances. After extracting planes in the reference data sets, the point-plane-incidences of the measured points and the reference planes are used to formulate the implicit constraints. We inspect the Velodyne HDL-64E S2 system as the best-known representative for this kind of sensor system. The usability and feasibility of the calibration procedure is demonstrated with real data sets representing building faces (walls, roof planes and ground. Beside the improvement of the point accuracy by considering the calibration results, we test the significance of the parameters related to the sensor model and consider the uncertainty of measurements w.r.t. the measured distances. The Velodyne returns two kinds of measurements – distances and encoder angles. To account for this, we perform a variance component estimation to obtain realistic standard deviations for the observations.

  14. In situ calibration of the Gamma Reaction History instrument using reference samples (“pucks” for areal density measurements

    Directory of Open Access Journals (Sweden)

    Hoffman N.M.

    2013-11-01

    Full Text Available The introduction of a sample of carbon, for example a disk or “puck”, near an imploding DT-filled capsule creates a source of 12C gamma rays that can serve as a reference for calibrating the response of the Gamma Reaction History (GRH detector [1]. Such calibration is important in the measurement of ablator areal density ⟨ρR⟩abl in plastic-ablator DT-filled capsules at OMEGA [2], by allowing ⟨ρR⟩abl to be inferred as a function of ratios of signals rather than from absolute measurements of signal magnitudes. Systematic uncertainties in signal measurements and detector responses therefore cancel, permitting more accurate measurements of ⟨ρR⟩abl.

  15. 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.

  16. Whole body counter calibration using Monte Carlo modeling with an array of phantom sizes based on national anthropometric reference data.

    Science.gov (United States)

    Shypailo, R J; Ellis, K J

    2011-05-21

    During construction of the whole body counter (WBC) at the Children's Nutrition Research Center (CNRC), efficiency calibration was needed to translate acquired counts of (40)K to actual grams of potassium for measurement of total body potassium (TBK) in a diverse subject population. The MCNP Monte Carlo n-particle simulation program was used to describe the WBC (54 detectors plus shielding), test individual detector counting response, and create a series of virtual anthropomorphic phantoms based on national reference anthropometric data. Each phantom included an outer layer of adipose tissue and an inner core of lean tissue. Phantoms were designed for both genders representing ages 3.5 to 18.5 years with body sizes from the 5th to the 95th percentile based on body weight. In addition, a spherical surface source surrounding the WBC was modeled in order to measure the effects of subject mass on room background interference. Individual detector measurements showed good agreement with the MCNP model. The background source model came close to agreement with empirical measurements, but showed a trend deviating from unity with increasing subject size. Results from the MCNP simulation of the CNRC WBC agreed well with empirical measurements using BOMAB phantoms. Individual detector efficiency corrections were used to improve the accuracy of the model. Nonlinear multiple regression efficiency calibration equations were derived for each gender. Room background correction is critical in improving the accuracy of the WBC calibration.

  17. Whole body counter calibration using Monte Carlo modeling with an array of phantom sizes based on national anthropometric reference data

    Science.gov (United States)

    Shypailo, R. J.; Ellis, K. J.

    2011-05-01

    During construction of the whole body counter (WBC) at the Children's Nutrition Research Center (CNRC), efficiency calibration was needed to translate acquired counts of 40K to actual grams of potassium for measurement of total body potassium (TBK) in a diverse subject population. The MCNP Monte Carlo n-particle simulation program was used to describe the WBC (54 detectors plus shielding), test individual detector counting response, and create a series of virtual anthropomorphic phantoms based on national reference anthropometric data. Each phantom included an outer layer of adipose tissue and an inner core of lean tissue. Phantoms were designed for both genders representing ages 3.5 to 18.5 years with body sizes from the 5th to the 95th percentile based on body weight. In addition, a spherical surface source surrounding the WBC was modeled in order to measure the effects of subject mass on room background interference. Individual detector measurements showed good agreement with the MCNP model. The background source model came close to agreement with empirical measurements, but showed a trend deviating from unity with increasing subject size. Results from the MCNP simulation of the CNRC WBC agreed well with empirical measurements using BOMAB phantoms. Individual detector efficiency corrections were used to improve the accuracy of the model. Nonlinear multiple regression efficiency calibration equations were derived for each gender. Room background correction is critical in improving the accuracy of the WBC calibration.

  18. Zotero : a free and open-source reference manager

    DEFF Research Database (Denmark)

    Courraud, Julie

    2014-01-01

    Zotero is a free, open-source reference management program compatible with Linux®, Mac®, and Windows® operating systems. Libraries are backed up online allowing sharing between computers and even multiple users. Zotero makes it easy to keep your reference library organised and ‘clean’. Reference...

  19. 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.

  20. 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.

  1. Self-calibrating lensless inline-holographic microscopy by a sample holder with reference structures.

    Science.gov (United States)

    Riesenberg, Rainer; Kanka, Mario

    2014-09-01

    A self-calibration technique for lensless compact chip-microscopes based on inline holography with pinhole illumination is presented. The pinhole illumination wave acts as reference and is needed for the reconstruction process. This reference wave is assumed to be spherical, so that its phase is already determined by the position of the pinhole in relation to the image sensor. It is shown that the reconstructed spatial resolution is strongly dependent on the estimation for the pinhole to sensor distance. A precision in the range of tens of microns was reached for microscopic imaging with a spatial resolution in the range of one micron. Therefore additional reference crosses are prepared lithographically on the sample holder. The hologram, which contains the optical information about the sample as well as the reference crosses, is used for calibration and image reconstruction at the same time. The presented technique was tested to allow the reconstruction of a spatial resolution corresponding to the limit of detection apertures of about 0.66. The technique was applied to holograms of test beads and blood smear samples.

  2. Advanced Calibration Source for Planetary and Earth Observing Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Radiometric calibration is critical to many NASA activities.  At NASA SSC, imaging cameras have been used in-situ to monitor propulsion test stand...

  3. Metrological tests of a 200 L calibration source for HPGE detector systems for assay of radioactive waste drums.

    Science.gov (United States)

    Boshkova, T; Mitev, K

    2016-03-01

    In this work we present test procedures, approval criteria and results from two metrological inspections of a certified large volume (152)Eu source (drum about 200L) intended for calibration of HPGe gamma assay systems used for activity measurement of radioactive waste drums. The aim of the inspections was to prove the stability of the calibration source during its working life. The large volume source was designed and produced in 2007. It consists of 448 identical sealed radioactive sources (modules) apportioned in 32 transparent plastic tubes which were placed in a wooden matrix which filled the drum. During the inspections the modules were subjected to tests for verification of their certified characteristics. The results show a perfect compliance with the NIST basic guidelines for the properties of a radioactive certified reference material (CRM) and demonstrate the stability of the large volume CRM-drum after 7 years of operation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. 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

  5. Rotating-coil calibration in a reference quadrupole, considering roll-angle misalignment and higher-order harmonics

    CERN Document Server

    AUTHOR|(CDS)2075492; Buzio, Marco; Köster, Oliver; Russenschuck, Stephan; Severino, Giordana

    2016-01-01

    A method is proposed for calibrating the radius of a rotating coil sensor by relaxing the metrological constraints on alignment and field errors of the reference quadrupole. A coil radius calibration considering a roll-angle misalignment of the measurement bench, the magnet, and the motor-drive unit is analyzed. Then, the error arising from higher-order harmonic field imperfections in the reference quadrupole is assessed. The method is validated by numerical field computation for both the higher-order harmonic errors and the roll-angle misalignment. Finally, an experimental proof-of-principle demonstration is car-ried out in a calibration magnet with sextupole harmonic.

  6. Improvements on the directional characteristics of a calibration sound source using the Boundary Element Method

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Barrera Figueroa, Salvador; Juhl, Peter Møller

    2008-01-01

    The project Euromet-792 aims to investigate and improve methods for secondary free-field calibration of microphones. In this framework, the comparison method is being studied at DFM in relation to the more usual substitution method of microphone calibration. The design of the sound source is of p...

  7. Neutron calibration field of bare {sup 252}Cf source in Vietnam

    Energy Technology Data Exchange (ETDEWEB)

    Le, Ngoc Thiem; Tran, Hoai Nam; Nguyen, Khai Tuan [Institute for Nuclear Science and Technology, Hanoi (Viet Nam); Trinh, Glap Van [Institute of Research and Development, Duy Tan University, Da Nang (Viet Nam)

    2017-02-15

    This paper presents the establishment and characterization of a neutron calibration field using a bare {sup 252}Cf source of low neutron source strength in Vietnam. The characterization of the field in terms of neutron flux spectra and neutron ambient dose equivalent rates were performed by Monte Carlo simulations using the MCNP5 code. The anisotropy effect of the source was also investigated. The neutron ambient dose equivalent rates at three reference distances of 75, 125, and 150 cm from the source were calculated and compared with the measurements using the Aloka TPS-451C neutron survey meters. The discrepancy between the calculated and measured values is found to be about 10%. To separate the scattered and the direct components from the total neutron flux spectra, an in-house shadow cone of 10% borated polyethylene was used. The shielding efficiency of the shadow cone was estimated using the MCNP5 code. The results confirmed that the shielding efficiency of the shadow cone is acceptable.

  8. Calibrating the sensing-coil radius by feed-down from a harmonic reference

    CERN Document Server

    Arpaia, Pasquale; Koster, Oliver; Russenschuck, Stephan; Severino, Giordana

    2015-01-01

    a harmonic field error of higher order is present in the calibration magnet. This also yields a calibration whena sextupole magnet is used, for example, when an insitu calibration is required. The proposed calibration method has been validated by simulations with the

  9. Well GeHP detector calibration for environmental measurements using reference materials

    Energy Technology Data Exchange (ETDEWEB)

    Tedjani, A. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Bourgogne Franche-Comté, F-25030 Besançon (France); Laboratoire de Physique des Rayonnements et Applications, Université de Jijel, B.P. 98, Oueled Aissa, Jijel 18000 (Algeria); Mavon, C. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Bourgogne Franche-Comté, F-25030 Besançon (France); Belafrites, A. [Laboratoire de Physique des Rayonnements et Applications, Université de Jijel, B.P. 98, Oueled Aissa, Jijel 18000 (Algeria); Degrelle, D. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Bourgogne Franche-Comté, F-25030 Besançon (France); Boumala, D. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Bourgogne Franche-Comté, F-25030 Besançon (France); Laboratoire de Physique des Rayonnements et Applications, Université de Jijel, B.P. 98, Oueled Aissa, Jijel 18000 (Algeria); Rius, D. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Bourgogne Franche-Comté, F-25030 Besançon (France); Groetz, J.-E., E-mail: jegroetz@univ-fcomte.fr [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Bourgogne Franche-Comté, F-25030 Besançon (France)

    2016-12-01

    A well-type detector installed in the Modane underground Laboratory (LSM) can combine both low background and high detection efficiency and it is well suited for the analysis of small amounts of environmental samples. Reference materials such as IAEA-447 (moss-soil), IAEA-RG-Th1 and IAEA-RG-U1 were used for the detector calibration, owing to a chemical composition close to those of the environmental samples. Nevertheless, the matrix effects and the true coincidence summing effects must be corrected from the full energy peak efficiency (FEPE). The FEPE was performed for a wide range of energy by a semi-empirical method using Monte Carlo simulation (MCNP6), intended for environmental measurements such as lake sediments dating. In the well geometry, the true coincidence summing effects could be very important and correction factors have been computed in three different ways.

  10. A high-precision position-based calibration table as the reference for angular accelerometer calibration experiment

    NARCIS (Netherlands)

    Jatiningrum, D.; De Visser, C.C.; Van Paassen, M.M.; Mulder, M.

    2015-01-01

    With the role of angular accelerometers in future fault-tolerant flight control systems, an in-depth evaluation of their performance then becomes a critical issue from the perspective of control system design. In this paper, a position-based calibration table is utilized to provide a sufficiently

  11. Comparison of information sources for case-referent data.

    Science.gov (United States)

    Persson, B; Karlsson, M; Axelson, O

    1994-10-01

    Exposure assessment and the ascertainment of cases are topics of main concern in epidemiologic research. To investigate validity aspects of this kind practically, a comparative evaluation was performed of information sources for case-referent data. Cases of Hodgkin's disease and non-Hodgkin's lymphoma diagnosed in 1975-1984 were collected from the Regional Cancer Register in Linköping. The study population was restricted to men 20-80 years of age at diagnosis. Living cases included in a previous case-referent study and the complementary cases from the register were compared with regard to the exposures indicated by job title and industrial branch, as given in the National Population Census in 1975. Furthermore, questionnaire-based exposure information from the case-referent study was compared with exposures derived from census information. Only 21% of all of the cases in the study base had been included in the questionnaire-based case-referent study. No major differences in the distribution of exposure were found for the two case series, except that fewer subjects were economically inactive in the previous case-referent study. No clear relations appeared between survival and particular exposures. Risk estimates derived from the present cancer register study were compared with corresponding estimates from the previous case-referent study. With restriction to only economically active cases, the risk estimates approached those of the case-referent study. This comparison showed that incomplete ascertainment of cases in a case-referent study was not an important source of bias, at least not in relation to what could be achieved by more complete case ascertainment through register linkage.

  12. Radio optical reference frame. 6: Additional source positions in the northern hemisphere

    Science.gov (United States)

    Fey, A. L.; Russell, J. L.; de Vegt, C.; Zacharias, N.; Johnston, K. J.; Ma, C.; Hall, D. M.; Holdenried, E. R.

    1994-01-01

    Radio and optical positions for northern hemisphere extragalactic sources are reported. Milliarcsecond (mas) accurate radio positions of 106 sources north of -2 deg declination are derived from Mark III Very Long Baseline Interferometry (VLBI) observations taken during ten experiments from 1990 January through 1990 October. The results presented supplement an ongoing project to define and maintain an all-sky radio/optical reference frame of 400 or more extragalactic sources with mas accurate radio and optical positions. Radio positions for 34 new sources are presented along with improved radio positions for 72 sources already in the reference frame catalog. An additional nine sources have been determined to be unsuitable reference frame objects. Radio observations of nine calibration sources tie the new positions to the existing catalogue. The radio positions of the new sources have formal mean errors of approximately 0.7 mas in right ascension and approximately 1.0 mas in declination. Sources for which we report improved radio positions now have formal mean errors of approximately 0.5 mas in both coordinates, an improvement in some cases by as much as 75%. Positions in the FK5 system have also been obtained for the optical counterparts of an additional five northern hemisphere radio sources using prime focus plates from the Kitt Peak National Observatory's 4 m telescope and a Ritchey-Chretien focus plate from the Calar Alto 2.2 m telescope. The optical positions have internal accuracies of about 0.03 sec and differ from the radio positions by about 0.07 sec on the average.

  13. Uniformity measurement of wide area reference sources for beta emitters.

    Science.gov (United States)

    Ohshiro, Masahiro; Shiina, Takuya; Yamada, Takahiro

    2016-03-01

    When conducting uniformity measurements of a wide area reference source with a detector having a window of a size similar to that of a gridded individual portion area on the source, it is important to carefully consider neighbor effects on measuring emission rates of the individual target portion resulting from the gap between the source and detector window. Optimization of the uniformity measurement conditions was studied for beta-emitting wide area reference sources in this study. A measurement system consisting of a PR-gas (Ar: 90%+CH4: 10%) flow type windowed proportional counter and a motorized XY stage was installed. This system is adapted to the uniformity measurement of two different types of (36)Cl sources made by different manufacturers. Uniformity measurement of a 100mm×100mm source divided into 16 portions of 6.25cm(2) (25mm squared) each could be conducted using our system under the present conditions with a neighbor effect of around 15% or less. The measurement results by use of this system were also compared with those using the imaging plate technique. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. High Flux Isotope Reactor cold neutron source reference design concept

    Energy Technology Data Exchange (ETDEWEB)

    Selby, D.L.; Lucas, A.T.; Hyman, C.R. [and others

    1998-05-01

    In February 1995, Oak Ridge National Laboratory`s (ORNL`s) deputy director formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. In May 1995, a team was formed to examine the feasibility of retrofitting a liquid hydrogen (LH{sub 2}) cold source facility into an existing HFIR beam tube. The results of this feasibility study indicated that the most practical location for such a cold source was the HB-4 beam tube. This location provides a potential flux environment higher than the Institut Laue-Langevin (ILL) vertical cold source and maximizes the space available for a future cold neutron guide hall expansion. It was determined that this cold neutron beam would be comparable, in cold neutron brightness, to the best facilities in the world, and a decision was made to complete a preconceptual design study with the intention of proceeding with an activity to install a working LH{sub 2} cold source in the HFIR HB-4 beam tube. During the development of the reference design the liquid hydrogen concept was changed to a supercritical hydrogen system for a number of reasons. This report documents the reference supercritical hydrogen design and its performance. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and testing, (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the conceptual design phase and establishes the baseline reference concept.

  15. Optical Positions of ICRF Sources Using UCAC Reference Stars

    Science.gov (United States)

    Assafin, M.; Zacharias, N.; Rafferty, T. J.; Zacharias, M. I.; da Silva Neto, D. N.; Andrei, A. H.; Vieira Martins, R.

    2003-05-01

    New optical positions on the 30 mas precision level have been obtained for 172 extragalactic International Celestial Reference Frame (ICRF) sources mainly in the range -30°sources, taken at the 1.60 m Cassegrain telescope of the Laboratório Nacional de Astrofísica, Brazil. A significant improvement in the optical positions was achieved over a previous determination of source positions. The mean optical positions are compared with the ICRF radio positions. The overall optical minus radio offsets are -6 and -15 mas for right ascension and declination, respectively. The formal internal error of these mean offsets is ~2.3 mas. This indicates a possible systematic error in the UCAC declinations of ~10 to 15 mas. Both the optical counterpart observations and the optical reference stars are observed about 9 yr after the Hipparcos mean epoch, and our results set an upper limit for a possible Hipparcos system rotation with respect to the International Celestial Reference System for the z-axis of about 0.7 mas yr-1. Based on observations obtained at Cerro Tololo Inter-American Observatory (CTIO) and in part on observations at the Laboratório Nacional de Astrofísica, Brazil. CTIO is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.

  16. Technology, safety, and costs of decommissioning a reference large irradiator and reference sealed sources

    Energy Technology Data Exchange (ETDEWEB)

    Haffner, D.R.; Villelgas, A.J. [Pacific Northwest Lab., Richland, WA (United States)

    1996-01-01

    This report contains the results of a study sponsored by the US Nuclear Regulatory Commission (NRC) to examine the decommissioning of large radioactive irradiators and their respective facilities, and a broad spectrum of sealed radioactive sources and their respective devices. Conceptual decommissioning activities are identified, and the technology, safety, and costs (in early 1993 dollars) associated with decommissioning the reference large irradiator and sealed source facilities are evaluated. The study provides bases and background data for possible future NRC rulemaking regarding decommissioning, for evaluation of the reasonableness of planned decommissioning actions, and for determining if adequate funds are reserved by the licensees for decommissioning of their large irradiator or sealed source facilities. Another purpose of this study is to provide background and information to assist licensees in planning and carrying out the decommissioning of their sealed radioactive sources and respective facilities.

  17. An absolute calibration source for laboratory and satellite infrared spectrometers.

    Science.gov (United States)

    Karoli, A R; Hickey, J R; Nelson, R E

    1967-07-01

    A compact blackbody source with an operating range of -40 degrees C to + 60 degrees C, utilizing thermoelectric heat pumping for uniform and stable temperature control, has been developed. The blackbody radiator (target) consists of a blackened honeycomb cavity array coupled to four matched, two-stage (cascade type) thermoelectric modules. This array, located within a temperature-regulated baffle system, produces a blackbody of high emissivity (>0.995) with small thermal gradients over the source area (65 cm(2)). Heat pumping of the target and baffles is controlled, independently, by two interference-free, proportional regulators which provide linear thermal control in both the heating and cooling modes of operation. Additional features of this blackbody source include excellent stability and rapid response to input temperature changes. Provisions are made for temperature monitoring at five locations on the target and at the center of each of the four baffle units. Performance characteristics and test results obtained in nonabsorbing atmospheres and under vacuum conditions are presented, as are the details of construction and operation.

  18. Novel reference site approach to prototyping, calibrating, and validating Earth observation data and products

    Science.gov (United States)

    Schaepman, M. E.; Morsdorf, F.; Leiterer, R.; Pfeifer, N.; Hollaus, M.; Disney, M.; Lewis, P.; Gastellu-Etchegorry, J.; Brazile, J.; Koetz, B.

    2012-12-01

    Much of global change is driven by feedback mechanisms taking place at spatial and temporal scales that are smaller than those currently incorporated in models. This severely limits our ability to predict, mitigate and adapt to environmental change at local and regional scales. Ideally, global modelling, reference sites and data will gradually converge to spatial and temporal scales where processes at their characteristic length scale can be compared, Ultimately; scale invariant observations and products would be the goal. But because of the inherent nature of a changing environment, spatio-temporal homogeneity of reference sites will remain a main concern. Globally distributed sites with naturally changing homogeneity and biome cover are of fundamental importance to understand potential bias errors in retrieval algorithms, amongst other benefits. We propose a new site concept using a highly detailed description of vegetation based on terrestrial and airborne laser scanning, extensive optical properties measurements as well as airborne imaging spectrometer data acquisition in combination with both, 1D and 3D radiative transfer models. Effects of horizontal and vertical heterogeneities and asymmetrical structure of vegetation and high temporal dynamics can be simulated and used in algorithm development, calibration and validation procedures. The approach allows comparison with heritage algorithms and products, and will support estimates of scale invariance for all spatial, spectral, and temporal dimensions. The site design is further using standards, allowing stage 1 & 2 validation according to CEOS/LPV (Committee on Earth Observation Satellites/ Land Product Validation Subgroup) recommendations as well as supporting the Quality Assurance Framework for Earth Observation (QA4EO) of the ESA/CEOS Cal/Val initiative. We demonstrate feasibility of the approach using the 'Laegeren' site (temperate deciduous forest, with dominant beech trees; 47°28'42.0" N; 8°21'51.8" E

  19. Effective density of Aquadag and fullerene soot black carbon reference materials used for SP2 calibration

    Directory of Open Access Journals (Sweden)

    M. Gysel

    2011-12-01

    Full Text Available The mass and effective density of black carbon (BC particles generated from aqueous suspensions of Aquadag and fullerene soot was measured and parametrized as a function of their mobility diameter. The measurements were made by two independent research groups by operating a differential mobility analyser (DMA in series with an aerosol particle mass analyser (APM or a Couette centrifugal particle mass analyser (CPMA. Consistent and reproducible results were found in this study for different production lots of Aquadag, indicating that the effective density of these particles is a stable quantity and largely unaffected by differences in aerosol generation procedures and suspension treatments. The effective density of fullerene soot particles from one production lot was also found to be stable and independent of suspension treatments. Some differences to previous literature data were observed for both Aquadag and fullerene soot at larger particle diameters. Knowledge of the exact relationship between mobility diameter and particle mass is of great importance, as DMAs are commonly used to size-select particles from BC reference materials for calibration of single particle soot photometers (SP2, which quantitatively detect the BC mass in single particles.

  20. The results of the PEP`93 intercomparison of reference cell calibrations and newer technology performance measurements: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Osterwald, C.R. [National Renewable Energy Lab., Golden, CO (United States); Anevsky, S. [All-Union Research Inst. for Optophysical Measurements, Moscow (Russian Federation); Barua, A.K. [Indian Association for the Cultivation of Science, Calcutta (India)] [and others

    1998-03-01

    This report presents the results of an international intercomparison of photovoltaic (PV) performance measurements and calibrations that took place from 1993 to 1997. The intercomparison, which was organized and operated by a group of representatives from national PV measurements laboratories, was accomplished by circulating two sample sets. One set, consisting of 20 silicon reference cells, was intended to form the basis of an international PV reference scale. A qualification procedure applied to the calibration results gave average calibration numbers with an overall standard deviation of less than 2% for the entire set. The second sample set was assembled from a wide range of newer technologies that present unique problems for PV measurements. As might be expected, these results showed much greater differences among the laboratories. Methods were then identified that should be used to measure such devices, along with problems to avoid. The report concludes with recommendations for future intercomparisons.

  1. Improvements on the directional characteristics of a calibration sound source using the Boundary Element Method

    DEFF Research Database (Denmark)

    Henriquez, Vicente Cutanda; Barrera Figueroa, Salvador; Juhl, Peter Møller

    2008-01-01

    The project Euromet-792 aims to investigate and improve methods for secondary free-field calibration of microphones. In this framework, the comparison method is being studied at DFM in relation to the more usual substitution method of microphone calibration. The design of the sound source...... is of particular importance to achieve a sound field that reaches both microphones with the same level and that is sufficiently uniform at the microphone positions, in order to reduce the effect of misalignment. An existing sound source has been modeled using the Boundary Element Method, and the simulations have...... been used to modify the source and make it suitable for this kind of calibration. It has been found that a central plug, already present in the device, can be re-shaped in such a way that makes the sound field on the microphone positions more uniform, even at rather high frequencies. Measurements have...

  2. A method of camera calibration in the measurement process with reference mark for approaching observation space target

    Science.gov (United States)

    Zhang, Hua; Zeng, Luan

    2017-11-01

    Binocular stereoscopic vision can be used for space-based space targets near observation. In order to solve the problem that the traditional binocular vision system cannot work normally after interference, an online calibration method of binocular stereo measuring camera with self-reference is proposed. The method uses an auxiliary optical imaging device to insert the image of the standard reference object into the edge of the main optical path and image with the target on the same focal plane, which is equivalent to a standard reference in the binocular imaging optical system; When the position of the system and the imaging device parameters are disturbed, the image of the standard reference will change accordingly in the imaging plane, and the position of the standard reference object does not change. The camera's external parameters can be re-calibrated by the visual relationship of the standard reference object. The experimental results show that the maximum mean square error of the same object can be reduced from the original 72.88mm to 1.65mm when the right camera is deflected by 0.4 degrees and the left camera is high and low with 0.2° rotation. This method can realize the online calibration of binocular stereoscopic vision measurement system, which can effectively improve the anti - jamming ability of the system.

  3. Performance of thin CaSO{sub 4}:Dy pellets for calibration of a {sup 90}Sr+{sup 90}Y source

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, M.L. [Instituto de Pesquisas Energeticas e Nucleares, Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Centro Regional de Ciencias Nucleares, Comissao Nacional de Energia Nuclear, Av. Prof. Luiz Freire, 200, 50740-540 Recife, PE (Brazil); Caldas, L.V.E. [Instituto de Pesquisas Energeticas e Nucleares, Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil)], E-mail: lcaldas@ipen.br

    2007-09-21

    Because of the radionuclide long half-life, {sup 90}Sr+{sup 90}Y, plane or concave sources, utilized in brachytherapy, have to be calibrated initially by the manufacturer and then routinely while they are utilized. Plane applicators can be calibrated against a conventional extrapolation chamber, but concave sources, because of their geometry, should be calibrated using relative dosimeters, as thermoluminescent (TL) materials. Thin CaSO{sub 4}:Dy pellets are produced at IPEN specially for beta radiation detection. Previous works showed the feasibility of this material in the dosimetry of {sup 90}Sr+{sup 90}Y sources in a wide range of absorbed dose in air. The aim of this work was to study the usefulness of these pellets for the calibration of a {sup 90}Sr+{sup 90}Y concave applicator. To reach this objective, a special phantom was designed and manufactured in PTFE with semi spherical geometry. Because of the dependence of the TL response on the mass of the pellet, the response of each pellet was normalized by its mass in order to reduce the dispersion on TL response. Important characteristics of this material were obtained in reference of a standard {sup 90}Sr+{sup 90}Y source, and the pellets were calibrated against a plane applicator; then they were utilized to calibrate the concave applicator.

  4. Herschel SPIRE fourier transform spectrometer: calibration of its bright-source mode

    Science.gov (United States)

    Lu, Nanyao; Polehampton, Edward T.; Swinyard, Bruce M.; Benielli, Dominique; Fulton, Trevor; Hopwood, Rosalind; Imhof, Peter; Lim, Tanya; Marchili, Nicola; Naylor, David A.; Schulz, Bernhard; Sidher, Sunil; Valtchanov, Ivan

    2014-07-01

    The Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) on board the ESA Herschel Space Observatory has two detector setting modes: (a) a nominal mode, which is optimized for observing moderately bright to faint astronomical targets, and (b) a bright-source mode recommended for sources significantly brighter than 500 Jy, within the SPIRE FTS bandwidth of 446.7-1544 GHz (or 194-671 microns in wavelength), which employs a reduced detector responsivity and out-of-phase analog signal amplifier/demodulator. We address in detail the calibration issues unique to the bright-source mode, describe the integration of the bright-mode data processing into the existing pipeline for the nominal mode, and show that the flux calibration accuracy of the bright-source mode is generally within 2 % of that of the nominal mode, and that the bright-source mode is 3 to 4 times less sensitive than the nominal mode.

  5. Use of a reference source in probability imaging.

    Science.gov (United States)

    Aime, C; Aristidi, E; Lantéri, H; Ricort, G

    1993-05-20

    We describe the relations between the statistics of the speckled image I(x) that is produced by an astronomical object at the focus of a telescope and the statistics of the point-source speckle pattern S(x) that is obtained under comparable conditions of turbulence. We show that the characteristic function (CF) of I(x) can be written as a central slice of a higher-order CF of S(x); as a consequence, probability density functions (PDF's) of I(x) and S(x) are related to one another by means of projections. An illustration, consisting of one-dimensional scans obtained with the European Southern Observatory's slit-scanning infrared specklograph, is made for real data. It is shown how the onefold and twofold PDF's of a double star can be synthesized from the twofold and the threefold PDF's of the reference source.

  6. Validation and calibration of structural models that combine information from multiple sources.

    Science.gov (United States)

    Dahabreh, Issa J; Wong, John B; Trikalinos, Thomas A

    2017-02-01

    Mathematical models that attempt to capture structural relationships between their components and combine information from multiple sources are increasingly used in medicine. Areas covered: We provide an overview of methods for model validation and calibration and survey studies comparing alternative approaches. Expert commentary: Model validation entails a confrontation of models with data, background knowledge, and other models, and can inform judgments about model credibility. Calibration involves selecting parameter values to improve the agreement of model outputs with data. When the goal of modeling is quantitative inference on the effects of interventions or forecasting, calibration can be viewed as estimation. This view clarifies issues related to parameter identifiability and facilitates formal model validation and the examination of consistency among different sources of information. In contrast, when the goal of modeling is the generation of qualitative insights about the modeled phenomenon, calibration is a rather informal process for selecting inputs that result in model behavior that roughly reproduces select aspects of the modeled phenomenon and cannot be equated to an estimation procedure. Current empirical research on validation and calibration methods consists primarily of methodological appraisals or case-studies of alternative techniques and cannot address the numerous complex and multifaceted methodological decisions that modelers must make. Further research is needed on different approaches for developing and validating complex models that combine evidence from multiple sources.

  7. Adaptive Sliding Mode Control of MEMS AC Voltage Reference Source

    Directory of Open Access Journals (Sweden)

    Ehsan Ranjbar

    2017-01-01

    Full Text Available The accuracy of physical parameters of a tunable MEMS capacitor, as the major part of MEMS AC voltage reference, is of great importance to achieve an accurate output voltage free of the malfunctioning noise and disturbance. Even though strenuous endeavors are made to fabricate MEMS tunable capacitors with desiderated accurate physical characteristics and ameliorate exactness of physical parameters’ values, parametric uncertainties ineluctably emerge in fabrication process attributable to imperfections in micromachining process. First off, this paper considers applying an adaptive sliding mode controller design in the MEMS AC voltage reference source so that it is capable of giving off a well-regulated output voltage in defiance of jumbling parametric uncertainties in the plant dynamics and also aggravating external disturbance imposed on the system. Secondly, it puts an investigatory comparison with the designed model reference adaptive controller and the pole-placement state feedback one into one’s prospective. Not only does the tuned adaptive sliding mode controller show remarkable robustness against slow parameter variation and external disturbance being compared to the pole-placement state feedback one, but also it immensely gets robust against the external disturbance in comparison with the conventional adaptive controller. The simulation results are promising.

  8. THE SUN AS A CALIBRATION SIGNAL SOURCE FOR L- AND S-BAND TELEMETRY

    Science.gov (United States)

    performance at all times. The sun provides sufficient signal strength in these bands, and its subtended angle of 0.5 deg from the earth is small enough to...communications link the sun could be used as a signal source for calibration purposes. Characteristics of solar emission are reviewed briefly, and the methods of determining receiving system noise temperature are developed.

  9. Primary calibrations of radionuclide solutions and sources for the EML quality assessment program

    Energy Technology Data Exchange (ETDEWEB)

    Fisenne, I.M. [Dept. of Energy, New York, NY (United States)

    1993-12-31

    The quality assurance procedures established for the operation of the U.S. Department of Energy`s Environmental Measurements Laboratory (DOE-EML`s) Quality Assessment Program (QAP) are essentially the same as those that are in effect for any EML program involving radiometric measurements. All these programs have at their core the use of radionuclide standards for their instrument calibration. This paper focuses on EML`s approach to the acquisition, calibration and application of a wide range of radionuclide sources that are required to meet its programmatic needs.

  10. Calibration of a time-resolved hard-x-ray detector using radioactive sources

    Energy Technology Data Exchange (ETDEWEB)

    Stoeckl, C., E-mail: csto@lle.rochester.edu; Theobald, W.; Regan, S. P.; Romanofsky, M. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States)

    2016-11-15

    A four-channel, time-resolved, hard x-ray detector (HXRD) has been operating at the Laboratory for Laser Energetics for more than a decade. The slope temperature of the hot-electron population in direct-drive inertial confinement fusion experiments is inferred by recording the hard x-ray radiation generated in the interaction of the electrons with the target. Measuring the energy deposited by hot electrons requires an absolute calibration of the hard x-ray detector. A novel method to obtain an absolute calibration of the HXRD using single photons from radioactive sources was developed, which uses a thermoelectrically cooled, low-noise, charge-sensitive amplifier.

  11. Astronomical calibration of 40Ar/39Ar reference minerals using high-precision, multi-collector (ARGUSVI) mass spectrometry

    Science.gov (United States)

    Phillips, D.; Matchan, E. L.; Honda, M.; Kuiper, K. F.

    2017-01-01

    The new generation of multi-collector mass spectrometers (e.g. ARGUSVI) permit ultra-high precision (1%) in 40K decay constants and the ages of natural reference minerals that form the basis of the technique. For example, reported ages for widely used 40Ar/39Ar reference materials, such as the ca. 28 Ma Fish Canyon Tuff sanidine (FCTs) and the ca. 1.2 Ma Alder Creek Rhyolite sanidine (ACRs), vary by >1%. Recent attempts to independently calibrate these reference minerals have focused on K-Ar analyses of the same minerals and inter-comparisons with astronomically tuned tephras in sedimentary sequences and U-Pb zircon ages from volcanic rocks. Most of these studies used older generation (effectively single-collector) mass spectrometers that employed peak-jumping analytical methods to acquire 40Ar/39Ar data. In this study, we reassess the inter-calibration and ages of commonly used 40Ar/39Ar reference minerals Fish Canyon Tuff sanidine (FCTs), Alder Creek Rhyolite sanidine (ACRs) and Mount Dromedary biotite (MD2b; equivalent to GA-1550 biotite), relative to the astronomically tuned age of A1 Tephra sanidine (A1Ts), Faneromeni section, Crete (Rivera et al., 2011), using a multi-collector ARGUSVI mass spectrometer. These analyses confirm the exceptional precision capability (0.1% in the 40Ar/39Ar ages of reference minerals without consideration of recoil artefacts, thus limiting the benefits of high precision multi-collector analyses. Significant improvement to the accuracy of the 40Ar/39Ar method (<0.1%) will require further inter-laboratory 40Ar/39Ar studies utilizing multi-collector mass spectrometry, additional constraints on recoil 39ArK loss from reference minerals, further resolution of discrepancies between astronomically tuned sedimentary successions and refinement of the 238U/206Pb zircon age cross-calibration approach.

  12. UV scale calibration transfer from an improved pyroelectric detector standard to field UV-A meters and 365 nm excitation sources

    Science.gov (United States)

    Eppeldauer, G. P.; Podobedov, V. B.; Cooksey, C. C.

    2017-05-01

    Calibration of the emitted radiation from UV sources peaking at 365 nm, is necessary to perform the ASTM required 1 mW/cm2 minimum irradiance in certain military material (ships, airplanes etc) tests. These UV "black lights" are applied for crack-recognition using fluorescent liquid penetrant inspection. At present, these nondestructive tests are performed using Hg-lamps. Lack of a proper standard and the different spectral responsivities of the available UV meters cause significant measurement errors even if the same UV-365 source is measured. A pyroelectric radiometer standard with spectrally flat (constant) response in the UV-VIS range has been developed to solve the problem. The response curve of this standard determined from spectral reflectance measurement, is converted into spectral irradiance responsivity with standard cryogenic radiometer. The flat pyroelectric radiometer standard can be used to perform uniform integrated irradiance measurements from all kinds of UV sources (with different peaks and distributions) without using any source standard. Using this broadband calibration method, yearly spectral calibrations for the reference UV (LED) sources and irradiance meters is not needed. Field UV sources and meters can be calibrated against the pyroelectric radiometer standard for broadband (integrated) irradiance and integrated responsivity. Using the broadband measurement procedure, the UV measurements give uniform results with significantly decreased uncertainties.

  13. A method for the temperature calibration of an infrared camera using water as a radiative source.

    Science.gov (United States)

    Bower, S M; Kou, J; Saylor, J R

    2009-09-01

    Presented here is an effective low-cost method for the temperature calibration of infrared cameras, for applications in the 0-100 degrees C range. The calibration of image gray level intensity to temperature is achieved by imaging an upwelling flow of water, the temperature of which is measured with a thermistor probe. The upwelling flow is created by a diffuser located below the water surface of a constant temperature water bath. The thermistor probe is kept immediately below the surface, and the distance from the diffuser outlet to the surface is adjusted so that the deformation of the water surface on account of the flow is small, yet the difference between the surface temperature seen by the camera and the bulk temperature measured by the thermistor is also small. The benefit of this method compared to typical calibration procedures is that, without sacrificing the quality of the calibration, relatively expensive commercial blackbodies are replaced by water as the radiative source (epsilon approximately 0.98 for the wavelengths considered here). A heat transfer analysis is provided, which improves the accuracy of the calibration method and also provides the user with guidance to further increases in accuracy of the method.

  14. Nickel replicas as calibration reference standards for industrial surface texture instruments

    DEFF Research Database (Denmark)

    Sammatini-Malberg, Maria-Pia

    The present report is a documentation of measurements carried out at DTU on Nickel replicas. The research is performed in the frame of the project with contract SMT4-CT97-2176 with title: Calibration Standards for Surface Topography Measuring Systems down to Nanometric Scale.......The present report is a documentation of measurements carried out at DTU on Nickel replicas. The research is performed in the frame of the project with contract SMT4-CT97-2176 with title: Calibration Standards for Surface Topography Measuring Systems down to Nanometric Scale....

  15. Availability of color calibration for consistent color display in medical images and optimization of reference brightness for clinical use

    Science.gov (United States)

    Iwai, Daiki; Suganami, Haruka; Hosoba, Minoru; Ohno, Kazuko; Emoto, Yutaka; Tabata, Yoshito; Matsui, Norihisa

    2013-03-01

    Color image consistency has not been accomplished yet except the Digital Imaging and Communication in Medicine (DICOM) Supplement 100 for implementing a color reproduction pipeline and device independent color spaces. Thus, most healthcare enterprises could not check monitor degradation routinely. To ensure color consistency in medical color imaging, monitor color calibration should be introduced. Using simple color calibration device . chromaticity of colors including typical color (Red, Green, Blue, Green and White) are measured as device independent profile connection space value called u'v' before and after calibration. In addition, clinical color images are displayed and visual differences are observed. In color calibration, monitor brightness level has to be set to quite lower value 80 cd/m2 according to sRGB standard. As Maximum brightness of most color monitors available currently for medical use have much higher brightness than 80 cd/m2, it is not seemed to be appropriate to use 80 cd/m2 level for calibration. Therefore, we propose that new brightness standard should be introduced while maintaining the color representation in clinical use. To evaluate effects of brightness to chromaticity experimentally, brightness level is changed in two monitors from 80 to 270cd/m2 and chromaticity value are compared with each brightness levels. As a result, there are no significant differences in chromaticity diagram when brightness levels are changed. In conclusion, chromaticity is close to theoretical value after color calibration. Moreover, chromaticity isn't moved when brightness is changed. The results indicate optimized reference brightness level for clinical use could be set at high brightness in current monitors .

  16. Accuracy assessment for the radiometric calibration of imaging sensors using preflight techniques relying on the sun as a source

    Science.gov (United States)

    Thome, K.; Czapla-Myers, J.; Kuester, M.; Anderson, N.

    2008-08-01

    The Remote Sensing Group (RSG) at the University of Arizona has performed high-accuracy radiometric calibration in the laboratory for more than 20 years in support of vicarious calibration of space-borne and airborne imaging sensors. Typical laboratory calibration relies on lamp-based sources which, while convenient to operate and control, do not simulate the solar spectrum that is the basic energy source for many of the imaging systems. Using the sun as a source for preflight radiometric calibration reduces uncertainties caused by the spectral mismatch between the preflight and inflight calibration, especially in the case in which a solar diffuser is the inflight calibration method. Difficulties in using the sun include varying atmospheric conditions, changing solar angle during the day and with season, and ensuring traceability to national standards. This paper presents several approaches using the sun as a radiometric calibration source coupled with the expected traceable accuracies for each method. The methods include direct viewing of the solar disk with the sensor of interest, illumination of the sensor's inflight solar diffuser by the sun, and illumination of an external diffuser that is imaged by the sensor. The results of the error analysis show that it is feasible to achieve preflight calibration using the sun as a source at the same level of uncertainty as those of lamp-based approaches. The error analysis is evaluated and compared to solar-radiation-based calibrations of one of RSG's laboratory-grade radiometers.

  17. What Is the Reference? An Examination of Alternatives to the Reference Sources Used in IES TM-30-15

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.

    2016-12-22

    A study was undertaken to document the role of the reference illuminant in the IES TM-30-15 method for evaluating color rendition. TM-30-15 relies on a relative reference scheme; that is, the reference illuminant and test source always have the same correlated color temperature (CCT). The reference illuminant is a Planckian radiator, model of daylight, or combination of those two, depending on the exact CCT of the test source. Three alternative reference schemes were considered: 1) either using all Planckian radiators or all daylight models; 2) using only one of ten possible illuminants (Planckian, daylight, or equal energy), regardless of the CCT of the test source; 3) using an off-Planckian reference illuminant (i.e., a source with a negative Duv). No reference scheme is inherently superior to another, with differences in metric values largely a result of small differences in gamut shape of the reference alternatives. While using any of the alternative schemes is more reasonable in the TM-30-15 evaluation framework than it was with the CIE CRI framework, the differences still ultimately manifest only as changes in interpretation of the results. References are employed in color rendering measures to provide a familiar point of comparison, not to establish an ideal source.

  18. A novel method of calibrating a MEMS inertial reference unit on a turntable under limited working conditions

    Science.gov (United States)

    Lu, Jiazhen; Liang, Shufang; Yang, Yanqiang

    2017-10-01

    Micro-electro-mechanical systems (MEMS) inertial measurement devices tend to be widely used in inertial navigation systems and have quickly emerged on the market due to their characteristics of low cost, high reliability and small size. Calibration is the most effective way to remove the deterministic error of an inertial reference unit (IRU), which in this paper consists of three orthogonally mounted MEMS gyros. However, common testing methods in the lab cannot predict the corresponding errors precisely when the turntable’s working condition is restricted. In this paper, the turntable can only provide a relatively small rotation angle. Moreover, the errors must be compensated exactly because of the great effect caused by the high angular velocity of the craft. To deal with this question, a new method is proposed to evaluate the MEMS IRU’s performance. In the calibration procedure, a one-axis table that can rotate a limited angle in the form of a sine function is utilized to provide the MEMS IRU’s angular velocity. A new algorithm based on Fourier series is designed to calculate the misalignment and scale factor errors. The proposed method is tested in a set of experiments, and the calibration results are compared to a traditional calibration method performed under normal working conditions to verify their correctness. In addition, a verification test in the given rotation speed is implemented for further demonstration.

  19. Preliminary assessment of several parameters to measure and compare usefulness of the CEOS reference pseudo-invariant calibration sites

    Science.gov (United States)

    Chander, Gyanesh; Angal, Amit; Xiong, Xiaoxiong (.; Helder, Dennis L.; Mishra, Nischal; Choi, Taeyoung (.; Wu, Aisheng

    2010-10-01

    Test sites are central to any future quality assurance and quality control (QA/QC) strategy. The Committee on Earth Observation Satellites (CEOS) Working Group for Calibration and Validation (WGCV) Infrared Visible Optical Sensors (IVOS) worked with collaborators around the world to establish a core set of CEOS-endorsed, globally distributed, reference standard test sites (both instrumented and pseudo-invariant) for the post-launch calibration of space-based optical imaging sensors. The pseudo-invariant calibration sites (PICS) have high reflectance and are usually made up of sand dunes with low aerosol loading and practically no vegetation. The goal of this paper is to provide preliminary assessment of "several parameters" than can be used on an operational basis to compare and measure usefulness of reference sites all over the world. The data from Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) and the Earth Observing-1 (EO-1) Hyperion sensors over the CEOS PICS were used to perform a preliminary assessment of several parameters, such as usable area, data availability, top-of-atmosphere (TOA) reflectance, at-sensor brightness temperature, spatial uniformity, temporal stability, spectral stability, and typical spectrum observed over the sites.

  20. Effects of Different Containers on Radioactivity Measurements using a Dose Calibrator with Special Reference to (111)In and (123)I.

    Science.gov (United States)

    Inoue, Yusuke; Abe, Yutaka; Kikuchi, Kei; Miyatake, Hiroki; Watanabe, Atsushi

    2017-01-01

    Low-energy characteristic x-rays emitted by (111)In and (123)I sources are easily absorbed by the containers of the sources, affecting radioactivity measurements using a dose calibrator. We examined the effects of different containers on the estimated activities. The radioactivities of (111)In, (123)I, (201)Tl, and (99m)Tc were measured in containers frequently employed in clinical practice in Japan. The (111)In measurements were performed in the vials A and B of the (111)In-pentetreotide preparation kit and in the plastic syringe. The activities of (123)I-metaiodobenzylguanidine and (201)Tl chloride were measured in the prefilled glass syringes and plastic syringes. The milking vial, vial A, vial B, and plastic syringe were used to assay (99m)Tc. For (111)In and (123)I, measurements were performed with and without a copper filter. The filter was inserted into the well of the dose calibrator to absorb low-energy x-rays. The relative estimate was defined as the ratio of the activity estimated with the dose calibrator to the standard activity. The estimated activities varied greatly depending on the container when (111)In and (123)I sources were assayed without the copper filter. The relative estimates of (111)In were 0.908, 1.072, and 1.373 in the vial A, vial B, and plastic syringe, respectively. The relative estimates of (123)I were 1.052 and 1.352 in the glass syringe and plastic syringe, respectively. Use of the copper filter eliminated the container-dependence in (111)In and (123)I measurements. Container-dependence was demonstrated in neither (201)Tl nor (99m)Tc measurements. The activities of (111)In and (123)I estimated with a dose calibrator differ greatly among the containers. Accurate estimation may be attained using the container-specific correction factor or using the copper filter.

  1. Accurate efficiency calibration of a low-energy HPGe detector using a monochromatic x-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Plagnard, Johann; Bobin, Christophe; Lepy, Marie-Christine [Commissariat a l' Energie Atomique, Laboratoire National Henri Becquerel, 91191 Gif-sur-Yvette Cedex (France)

    2007-05-15

    HPGe detector efficiency has been calibrated using complementary methods involving radioactive x-ray standards, reference synchrotron flux (Super ACO, LURE, France) and a monochromatic x-ray source (SOLEX), combined with Monte Carlo simulation. In the study described here, SOLEX was used to determine the thickness of detector components that create absorption sites in front of the active zone of the detector, by energy scanning in the vicinity of their K and L binding energies. The layers of aluminium (infrared shielding), nickel (electrical contact) and germanium (dead layer) have been measured. This approach ensures accurate determination of the thickness of each component and enables the detector efficiency calculation by Monte Carlo simulation. Differences between simulated data and experimental efficiency values are about 1-5% at energies above 1400 eV and reach 20% at lower energies. (authors)

  2. Argon mini-arc meets its match: use of a laser-driven plasma source in ultraviolet-detector calibrations.

    Science.gov (United States)

    Arp, Uwe; Vest, Robert; Houston, Jeanne; Lucatorto, Thomas

    2014-02-20

    The National Institute of Standards and Technology operates two spectral comparator facilities, both of which are used to provide detector calibrations from the ultraviolet to the near-infrared spectral range. One, the Ultraviolet Spectral Comparator Facility (UV SCF), has been in operation for more than two decades, providing one of the core calibration services. Recently, the illumination source used in the UV SCF has been changed from an argon mini-arc source to a laser-driven plasma light source. This new source has higher brightness, a smaller source size, better temporal stability, and much better conversion efficiency than the previous source. The improvements in the capabilities are summarized.

  3. Direct intensity calibration of X-ray grazing-incidence microscopes with home-lab source

    Science.gov (United States)

    Li, Yaran; Xie, Qing; Chen, Zhiqiang; Xin, Qiuqi; Wang, Xin; Mu, Baozhong; Wang, Zhanshan; Liu, Shenye; Ding, Yongkun

    2018-01-01

    Direct intensity calibration of X-ray grazing-incidence microscopes is urgently needed in quantitative studies of X-ray emission from laser plasma sources in inertial confinement fusion. The existing calibration methods for single reflecting mirrors, crystals, gratings, filters, and X-ray detectors are not applicable for such X-ray microscopes due to the specific optical structure and the restrictions of object-image relation. This article presents a reliable and efficient method that can be performed using a divergent X-ray source and an energy dispersive Si-PIN (silicon positive-intrinsic-negative) detector in an ordinary X-ray laboratory. The transmission theory of X-ray flux in imaging diagnostics is introduced, and the quantities to be measured are defined. The calibration method is verified by a W/Si multilayer-coated Kirkpatrick-Baez microscope with a field of view of ˜95 μm at 17.48 keV. The mirror reflectance curve in the 1D coordinate is drawn with a peak value of 20.9% and an uncertainty of ˜6.0%.

  4. Calibration of reference values used in evaluation of leaf analysis for Isparta Region at apple trees

    Directory of Open Access Journals (Sweden)

    Kadir UÇGUN

    2013-12-01

    Full Text Available This study was carried out on leaves taken from apple orchards been in Isparta province in 2010-2011. With this study, reference values were determined for apple trees and compared with other reference values. 150 orchards were determined where cultivated intensively apple as fruit production amount and leaf samples were taken at the beginning of July. N, P, K, Ca, Mg, Mn, Zn and B were analyzed in taken leaf samples. The upper and lower level was determined for each nutrient. Reference values of N, P, K, Mg, Ca, Mn, Zn and B were %2.45-2.85, %0.18-0.24, %1.57-1.99, %1.10-1.41, %0.32-0.43, 39-80 ppm, 13-26 ppm nd 33-42 ppm, respectively. When these reference values were compared with reference values obtained previous research, it was determined that N reference values of this research were higher than previous results, but Zn values were lower and the rest of the nutrient values were similar with the other references values.

  5. Building Energy Simulation Test for Existing Homes (BESTEST-EX): Instructions for Implementing the Test Procedure, Calibration Test Reference Results, and Example Acceptance-Range Criteria

    Energy Technology Data Exchange (ETDEWEB)

    Judkoff, R.; Polly, B.; Bianchi, M.; Neymark, J.; Kennedy, M.

    2011-08-01

    This publication summarizes building energy simulation test for existing homes (BESTEST-EX): instructions for implementing the test procedure, calibration tests reference results, and example acceptance-range criteria.

  6. Stable isotope analyses of oxygen (18 O:17 O:16 O) and chlorine (37 Cl:35 Cl) in perchlorate: reference materials, calibrations, methods, and interferences.

    Science.gov (United States)

    Böhlke, J K; Mroczkowski, Stanley J; Sturchio, Neil C; Heraty, Linnea J; Richman, Kent W; Sullivan, Donald B; Griffith, Kris N; Gu, Baohua; Hatzinger, Paul B

    2017-01-15

    Perchlorate (ClO4- ) is a common trace constituent of water, soils, and plants; it has both natural and synthetic sources and is subject to biodegradation. The stable isotope ratios of Cl and O provide three independent quantities for ClO4- source attribution and natural attenuation studies: δ37 Cl, δ18 O, and δ17 O (or Δ17 O or 17 Δ) values. Documented reference materials, calibration schemes, methods, and interferences will improve the reliability of such studies. Three large batches of KClO4 with contrasting isotopic compositions were synthesized and analyzed against VSMOW-SLAP, atmospheric O2 , and international nitrate and chloride reference materials. Three analytical methods were tested for O isotopes: conversion of ClO4- to CO for continuous-flow IRMS (CO-CFIRMS), decomposition to O2 for dual-inlet IRMS (O2-DIIRMS), and decomposition to O2 with molecular-sieve trap (O2-DIIRMS+T). For Cl isotopes, KCl produced by thermal decomposition of KClO4 was reprecipitated as AgCl and converted into CH3 Cl for DIIRMS. KClO4 isotopic reference materials (USGS37, USGS38, USGS39) represent a wide range of Cl and O isotopic compositions, including non-mass-dependent O isotopic variation. Isotopic fractionation and exchange can affect O isotope analyses of ClO4- depending on the decomposition method. Routine analyses can be adjusted for such effects by normalization, using reference materials prepared and analyzed as samples. Analytical errors caused by SO42- , NO3- , ReO42- , and C-bearing contaminants include isotope mixing and fractionation effects on CO and O2 , plus direct interference from CO2 in the mass spectrometer. The results highlight the importance of effective purification of ClO4- from environmental samples. KClO4 reference materials are available for testing methods and calibrating isotopic data for ClO4- and other substances with widely varying Cl or O isotopic compositions. Current ClO4- extraction, purification, and analysis techniques provide

  7. Stable isotope analyses of oxygen (18O:17O:16O) and chlorine (37Cl:35Cl) in perchlorate: reference materials, calibrations, methods, and interferences

    Science.gov (United States)

    Böhlke, John Karl; Mroczkowski, Stanley J.; Sturchio, Neil C.; Heraty, Linnea J.; Richman, Kent W.; Sullivan, Donald B.; Griffith, Kris N.; Gu, Baohua; Hatzinger, Paul B.

    2017-01-01

    RationalePerchlorate (ClO4−) is a common trace constituent of water, soils, and plants; it has both natural and synthetic sources and is subject to biodegradation. The stable isotope ratios of Cl and O provide three independent quantities for ClO4− source attribution and natural attenuation studies: δ37Cl, δ18O, and δ17O (or Δ17O or 17Δ) values. Documented reference materials, calibration schemes, methods, and interferences will improve the reliability of such studies.MethodsThree large batches of KClO4 with contrasting isotopic compositions were synthesized and analyzed against VSMOW-SLAP, atmospheric O2, and international nitrate and chloride reference materials. Three analytical methods were tested for O isotopes: conversion of ClO4− to CO for continuous-flow IRMS (CO-CFIRMS), decomposition to O2 for dual-inlet IRMS (O2-DIIRMS), and decomposition to O2 with molecular-sieve trap (O2-DIIRMS+T). For Cl isotopes, KCl produced by thermal decomposition of KClO4 was reprecipitated as AgCl and converted into CH3Cl for DIIRMS.ResultsKClO4 isotopic reference materials (USGS37, USGS38, USGS39) represent a wide range of Cl and O isotopic compositions, including non-mass-dependent O isotopic variation. Isotopic fractionation and exchange can affect O isotope analyses of ClO4− depending on the decomposition method. Routine analyses can be adjusted for such effects by normalization, using reference materials prepared and analyzed as samples. Analytical errors caused by SO42−, NO3−, ReO42−, and C-bearing contaminants include isotope mixing and fractionation effects on CO and O2, plus direct interference from CO2 in the mass spectrometer. The results highlight the importance of effective purification of ClO4− from environmental samples.ConclusionsKClO4 reference materials are available for testing methods and calibrating isotopic data for ClO4− and other substances with widely varying Cl or O isotopic compositions. Current ClO4−extraction, purification

  8. Calibration of the WFC3 Emission-Line Filters and Application of the Results to the Greatest Source of Uncertainties in Determining Abundances in Gase

    Science.gov (United States)

    O'Dell, C.

    2010-09-01

    The WFC3 is arguably the most powerful camera that has been used on the HST. This capability arises in part from the uniquely complete set of narrow-band filters that were incorporated for making images of nebulae in emission-lines. Turning these oft-times beautiful images into scientifically useful information requires accurate flux calibration of the filters, which is the first subject of this proposal. The present plan is that WFC3 calibration will be done from pre-launch properties of the filters and observations of stars. The WFC3 filters transmission profiles were measured pre-launch in a different optical configuration and temperature than applies within the WFC3, thus rendering uncertain any flux calibrations tied to those pre-launch measurements. We propose to perform a ?ground-truth? calibration of the WFC3 narrow-band filters using NGC 6720 as a reference source, in much the same manner that the PI did when calibrating similar filters in the WFPC2 and the ACS.These new calibrations will then be used to address the t^2 problem in Gaseous Nebulae. This is the source of uncertainties in the relative abundances of factors 1.1 to 10 and undermines efforts to trace the abundance variations within our Galaxy and other galaxies. The t^2 problem remains unresolved after four decades and the NGC 6720 images used for the filter calibration may resolve the problem if they show that regions of small-scale temperature fluctuations arise from low-temperature shadow-zones behind knots that are known to exist within the nebula or from high-temperature shocks that have been posited. Unlike the case of the Orion Nebula, where we have addressed this problem with fewer diagnostic filters, the geometry of NGC 6720 is ideally favorable for seeing these temperature variations and identifying their cause.

  9. Estimation of surgical tool-tip tracking error distribution in coordinate reference frame involving pivot calibration uncertainty.

    Science.gov (United States)

    Min, Zhe; Ren, Hongliang; Meng, Max Q-H

    2017-10-01

    Accurate understanding of surgical tool-tip tracking error is important for decision making in image-guided surgery. In this Letter, the authors present a novel method to estimate/model surgical tool-tip tracking error in which they take pivot calibration uncertainty into consideration. First, a new type of error that is referred to as total target registration error (TTRE) is formally defined in a single-rigid registration. Target localisation error (TLE) in two spaces to be registered is considered in proposed TTRE formulation. With first-order approximation in fiducial localisation error (FLE) or TLE magnitude, TTRE statistics (mean, covariance matrix and root-mean-square (RMS)) are then derived. Second, surgical tool-tip tracking error in optical tracking system (OTS) frame is formulated using TTRE when pivot calibration uncertainty is considered. Finally, TTRE statistics of tool-tip in OTS frame are then propagated relative to a coordinate reference frame (CRF) rigid-body. Monte Carlo simulations are conducted to validate the proposed error model. The percentage passing statistical tests that there is no difference between simulated and theoretical mean and covariance matrix of tool-tip tracking error in CRF space is more than 90% in all test cases. The RMS percentage difference between simulated and theoretical tool-tip tracking error in CRF space is within 5% in all test cases.

  10. MTS-6 detectors calibration by using 239Pu-Be neutron source

    Directory of Open Access Journals (Sweden)

    Małgorzata Wrzesień

    2017-12-01

    Full Text Available Background: Thermoluminescent detectors, type MTS-6, containing isotope 6Li (lithium are sensitive in the range of thermal neutron energy; the 239Pu-Be (plutonium-and-beryllium source emits neutrons in the energy range from 1 to 11 MeV. These seemingly contradictory elements may be combined by using the paraffin moderator, a determined density of thermal neutrons in the paraffin block and a conversion coefficient neutron flux to kerma, not forgetting the simultaneous registration of the photon radiation inseparable from the companion neutron radiation. The main aim of this work is to present the idea of calibration of thermoluminescent detectors that consist of a 6Li isotope, by using 239Pu-Be neutron radiation source. Material and Methods: In this work, MTS-6 and MTS-7 thermoluminescent detectors and a plutonium-and-beryllium (239Pu-Be neutron source were used. Paraffin wax fills the block, acting as a moderator. The calibration idea was based on the determination of dose equivalent rate based on the average kerma rate calculated taking into account the empirically determined function describing the density of thermal neutron flux in the paraffin block and a conversion coefficient neutron flux to kerma. Results: The calculated value of the thermal neutron flux density was 1817.5 neutrons/cm2/s and the average value of kerma rate determined on this basis amounted to 244 μGy/h, and the dose equivalent rate 610 μSv/h. The calculated value allowed for the assessment of the length of time of exposure of the detectors directly in the paraffin block. Conclusions: The calibration coefficient for the used batch of detectors is (6.80±0.42×10–7 Sv/impulse. Med Pr 2017;68(6:705–710

  11. MTS-6 detectors calibration by using 239Pu-Be neutron source.

    Science.gov (United States)

    Wrzesień, Małgorzata; Albiniak, Łukasz; Al-Hameed, Hiba

    2017-10-17

    Thermoluminescent detectors, type MTS-6, containing isotope 6Li (lithium) are sensitive in the range of thermal neutron energy; the 239Pu-Be (plutonium-and-beryllium) source emits neutrons in the energy range from 1 to 11 MeV. These seemingly contradictory elements may be combined by using the paraffin moderator, a determined density of thermal neutrons in the paraffin block and a conversion coefficient neutron flux to kerma, not forgetting the simultaneous registration of the photon radiation inseparable from the companion neutron radiation. The main aim of this work is to present the idea of calibration of thermoluminescent detectors that consist of a 6Li isotope, by using 239Pu-Be neutron radiation source. In this work, MTS-6 and MTS-7 thermoluminescent detectors and a plutonium-and-beryllium (239Pu-Be) neutron source were used. Paraffin wax fills the block, acting as a moderator. The calibration idea was based on the determination of dose equivalent rate based on the average kerma rate calculated taking into account the empirically determined function describing the density of thermal neutron flux in the paraffin block and a conversion coefficient neutron flux to kerma. The calculated value of the thermal neutron flux density was 1817.5 neutrons/cm2/s and the average value of kerma rate determined on this basis amounted to 244 μGy/h, and the dose equivalent rate 610 μSv/h. The calculated value allowed for the assessment of the length of time of exposure of the detectors directly in the paraffin block. The calibration coefficient for the used batch of detectors is (6.80±0.42)×10-7 Sv/impulse. Med Pr 2017;68(6):705-710.

  12. A calibrated UV-LED based light source for water purification and characterisation of photocatalysis.

    Science.gov (United States)

    Sergejevs, A; Clarke, C T; Allsopp, D W E; Marugan, J; Jaroenworaluck, A; Singhapong, W; Manpetch, P; Timmers, R; Casado, C; Bowen, C R

    2017-11-08

    Photocatalysis has a potential to become a cost effective industrial process for water cleaning. One of the most studied photocatalysts is titanium dioxide which, as a wide band gap semiconductor, requires ultraviolet (UV) light for its photoactivation. This is at the wavelengths where the efficiency of present-day light emitting diodes (LEDs) decreases rapidly, which presents a challenge in the use of UV-LEDs for commercially viable photocatalysis. There is also a need for accurate photocatalysis measurement of remediation rates of water-borne contaminants for determining optimum exposure doses in industrial applications. In response to these challenges, this paper describes a UV-LED based photocatalytic test reactor that provides a calibrated adjustable light source and pre-defined test conditions to remove as many sources of uncertainty in photocatalytic analysis as possible and thereby improve data reliability. The test reactor provides a selectable intensity of up to 1.9 kW m -2 at the photocatalyst surface. The comparability of the results is achieved through the use of pre-calibration and control electronics that minimize the largest sources of uncertainty; most notably variations in the intensity and directionality of the UV light emission of LEDs and in LED device heating.

  13. Supervised Vicarious Calibration (SVC of Multi-Source Hyperspectral Remote-Sensing Data

    Directory of Open Access Journals (Sweden)

    Anna Brook

    2015-05-01

    Full Text Available Introduced in 2011, the supervised vicarious calibration (SVC approach is a promising approach to radiometric calibration and atmospheric correction of airborne hyperspectral (HRS data. This paper presents a comprehensive study by which the SVC method has been systematically examined and a complete protocol for its practical execution has been established—along with possible limitations encountered during the campaign. The technique was applied to multi-sourced HRS data in order to: (1 verify the at-sensor radiometric calibration and (2 obtain radiometric and atmospheric correction coefficients. Spanning two select study sites along the southeast coast of France, data were collected simultaneously by three airborne sensors (AisaDUAL, AHS and CASI-1500i aboard two aircrafts (CASA of National Institute for Aerospace Technology INTA ES and DORNIER 228 of NERC-ARSF Centre UK. The SVC ground calibration site was assembled along sand dunes near Montpellier and the thematic data were acquired from other areas in the south of France (Salon-de-Provence, Marseille, Avignon and Montpellier on 28 October 2010 between 12:00 and 16:00 UTC. The results of this study confirm that the SVC method enables reliable inspection and, if necessary, in-situ fine radiometric recalibration of airborne hyperspectral data. Independent of sensor or platform quality, the SVC approach allows users to improve at-sensor data to obtain more accurate physical units and subsequently improved reflectance information. Flight direction was found to be important, whereas the flight altitude posed very low impact. The numerous rules and major outcomes of this experiment enable a new standard of atmospherically corrected data based on better radiometric output. Future research should examine the potential of SVC to be applied to super-and-hyperspectral data obtained from on-orbit sensors.

  14. Constrained Maximum Likelihood Estimation for Model Calibration Using Summary-level Information from External Big Data Sources.

    Science.gov (United States)

    Chatterjee, Nilanjan; Chen, Yi-Hau; Maas, Paige; Carroll, Raymond J

    2016-03-01

    Information from various public and private data sources of extremely large sample sizes are now increasingly available for research purposes. Statistical methods are needed for utilizing information from such big data sources while analyzing data from individual studies that may collect more detailed information required for addressing specific hypotheses of interest. In this article, we consider the problem of building regression models based on individual-level data from an "internal" study while utilizing summary-level information, such as information on parameters for reduced models, from an "external" big data source. We identify a set of very general constraints that link internal and external models. These constraints are used to develop a framework for semiparametric maximum likelihood inference that allows the distribution of covariates to be estimated using either the internal sample or an external reference sample. We develop extensions for handling complex stratified sampling designs, such as case-control sampling, for the internal study. Asymptotic theory and variance estimators are developed for each case. We use simulation studies and a real data application to assess the performance of the proposed methods in contrast to the generalized regression (GR) calibration methodology that is popular in the sample survey literature.

  15. Radio Frequency Plasma Discharge Lamps for Use as Stable Calibration Light Sources

    Science.gov (United States)

    McAndrew, Brendan; Cooper, John; Arecchi, Angelo; McKee, Greg; Durell, Christopher

    2012-01-01

    Stable high radiance in visible and near-ultraviolet wavelengths is desirable for radiometric calibration sources. In this work, newly available electrodeless radio-frequency (RF) driven plasma light sources were combined with research grade, low-noise power supplies and coupled to an integrating sphere to produce a uniform radiance source. The stock light sources consist of a 28 VDC power supply, RF driver, and a resonant RF cavity. The RF cavity includes a small bulb with a fill gas that is ionized by the electric field and emits light. This assembly is known as the emitter. The RF driver supplies a source of RF energy to the emitter. In commercial form, embedded electronics within the RF driver perform a continual optimization routine to maximize energy transfer to the emitter. This optimization routine continually varies the light output sinusoidally by approximately 2% over a several-second period. Modifying to eliminate this optimization eliminates the sinusoidal variation but allows the output to slowly drift over time. This drift can be minimized by allowing sufficient warm-up time to achieve thermal equilibrium. It was also found that supplying the RF driver with a low-noise source of DC electrical power improves the stability of the lamp output. Finally, coupling the light into an integrating sphere reduces the effect of spatial fluctuations, and decreases noise at the output port of the sphere.

  16. Numeric data services and sources for the general reference librarian

    CERN Document Server

    Kellam, Lynda

    2011-01-01

    The proliferation of online access to social science statistical and numeric data sources, such as the U.S. Census Bureau's American Fact Finder, has lead to an increased interest in supporting these sources in academic libraries. Many large libraries have been able to devote staff to data services for years, and recently smaller academic libraries have recognized the need to provide numeric data services and support. This guidebook serves as a primer to developing and supporting social science statistical and numerical data sources in the academic library. It provides strategies for the estab

  17. A stable and inexpensive wavelength reference for precise wavelength calibration of radial velocity spectrographs

    Science.gov (United States)

    Feger, Tobias; Ireland, Michael J.; Bento, Joao; Bacigalupo, Carlos

    2014-08-01

    We present a stable, inexpensive wavelength reference, based on a white-light interferometer for the use on current and future (arrays of) diffraction-limited radial velocity (RV) spectrographs. The primary aim of using an interferometer is to obtain a dense sinusoidal wavelength reference with spectral coverage between 450-650 nm. Its basic setup consists of an unbalanced fiber Mach-Zehnder interferometer (FMZI) that creates an interference pattern in the spectral domain due to superposition of phase delayed light, set by a fixed optical path-length difference (OPD). To achieve long-term stability, the interferometer is actively locked to a stable atomic line. The system operates in closed-loop using a thermo-optic modulator as the phase feedback component. We conducted stability measurements by superimposing the wavelength reference with thorium-argon (ThAr) emission lines and found the differential RMS shift to be ~5 m s-1 within 30 minute bins in an experiment lasting 5 hours.

  18. Sources of inspiration? Making sense of scientific references in patents

    NARCIS (Netherlands)

    Callaert, Julie; Pellens, Maikel; van Looy, Bart

    2013-01-01

    Scientific references in patent documents can be used as indicators signaling science-technology interactions. Whether they reflect a direct ‘knowledge flow’ from science to technology is subject of debate. Based on 33 interviews with inventors at Belgian firms and knowledge-generating institutes

  19. Shakespeare: A Student's Guide to Basic Reference Sources.

    Science.gov (United States)

    Claener, Anne, Comp.

    Basic and standard reference materials dealing with William Shakespeare are listed in this bibliography. Annotated entries are grouped under the following headings: concordances, dictionaries, encyclopedias and handbooks, and bibliographies. The section on bibliographies is further divided into lists of editions of Shakespeare's work, general…

  20. Geometry calibration between X-ray source and detector for tomosynthesis with a portable X-ray system.

    Science.gov (United States)

    Sato, Kohei; Ohnishi, Takashi; Sekine, Masashi; Haneishi, Hideaki

    2017-05-01

    Tomosynthesis is attracting attention as a low-dose tomography technology compared with X-ray CT. However, conventional tomosynthesis imaging devices are large and stationary. Furthermore, there is a limitation in the working range of the X-ray source during image acquisition. We have previously proposed the use of a portable X-ray device for tomosynthesis that can be used for ward rounds and emergency medicine. The weight of this device can be reduced by using a flat panel detector (FPD), and flexibility is realized by the free placement of the X-ray source and FPD. Tomosynthesis using a portable X-ray device requires calibration of the geometry between the X-ray source and detector at each image acquisition. We propose a method for geometry calibration and demonstrate tomosynthesis image reconstruction by this method. An image processing-based calibration method using an asymmetric and multilayered calibration object (AMCO) is presented. Since the AMCO is always attached to the X-ray source housing for geometry calibration, the additional setting of a calibration object or marker around or on the patients is not required. The AMCO's multilayer structure improves the calibration accuracy, especially in the out-of-plane direction. Two experiments were conducted. The first was performed to evaluate the calibration accuracy using an XY positioning stage and a gonio stage. As a result, an accuracy of approximately 1 mm was achieved both in the in-plane and out-of-plane directions. An angular accuracy of approximately [Formula: see text] was confirmed. The second experiment was conducted to evaluate the reconstructed image using a foot model phantom. Only the sagittal plane could be clearly observed with the proposed method. We proposed a tomosynthesis imaging system using a portable X-ray device. From the experimental results, the proposed method could provide sufficient calibration accuracy and a clear sagittal plane of the reconstructed tomosynthesis image.

  1. Select Bibliography and Overview of Bunge's Publications Related to Reference Sources.

    Science.gov (United States)

    Gelfand, Julia

    1999-01-01

    Includes citations to five articles written by Charles Bunge related to reference sources and provides an overview of his views on reference materials. Highlights include sources with the most information; images and illustrative material, especially in light of technology; and collection development, including reviewing tools. (LRW)

  2. The Supercontinuum Laser Source Fundamentals with Updated References

    CERN Document Server

    Alfano, Robert R

    2006-01-01

    Photonics and nonlinear optics are important areas of science, engineering and technology. One of the most important ultrafast nonlinear optical processes is the supercontinuum (SC) – the production of intense white light pulses covering: uv, visible, NIR, MIR, and IR. It is produced using ultrashort laser pulses (ps/fs) to produce the ultrabroad band of frequencies. This book covers the fundamental principles and surveys research of current thinkers and experts in the field with updated references of the key breakthroughs over the past decade and a half. The application of SC are time-resolved pump-SC probe absorption and excitation spectroscopy for chemistry, biology and physics fundamental processes; optical coherence tomography; ultrashort pulse generation in femtosecond and attosecond regions; frequency clocks; phase stabilization; optical communication; atmospheric science; lightning control; optical medical imaging; biological cell imaging; and metrology standards.

  3. Timing reference generators and chopper controllers for neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, R.; Merl, R.; Rose, C. [Los Alamos National Laboratory, Los Alamos, NM (United States)

    2001-03-01

    Due to AC-power-grid frequency fluctuations, the designers for accelerator-based spallation-neutron facilities have worked to optimize the competing and contrasting demands of accelerator and neutron chopper performance. Powerful new simulation techniques have enabled the modeling of the timing systems that integrate chopper controllers and chopper hardware. For the first time, we are able to quantitatively access the tradeoffs between these two constraints and design or upgrade a facility to optimize total system performance. Thus, at LANSCE, we now operate multiple chopper systems and the accelerator as simple slaves to a single master-timing-reference generator. For the SNS we recommend a similar system that is somewhat less tightly coupled to the power grid. (author)

  4. Validation of a Monte Carlo Model of the Fork Detector with a Calibrated Neutron Source

    Science.gov (United States)

    Borella, Alessandro; Mihailescu, Liviu-Cristian

    2014-02-01

    The investigation of experimental methods for safeguarding spent fuel elements is one of the research areas at the Belgian Nuclear Research Centre SCK•CEN. A version of the so-called Fork Detector has been designed at SCK•CEN and is in use at the Belgian Nuclear Power Plant of Doel for burnup determination purposes. The Fork Detector relies on passive neutron and gamma measurements for the assessment of the burnup and safeguards verification activities. In order to better evaluate and understand the method and in view to extend its capabilities, an effort to model the Fork detector was made with the code MCNPX. A validation of the model was done in the past using spent fuel measurement data. This paper reports about the measurements carried out at the Laboratory for Nuclear Calibrations (LNK) of SCK•CEN with a 252Cf source calibrated according to ISO 8529 standards. The experimental data are presented and compared with simulations. In the simulations, not only was the detector modeled but also the measurement room was taken into account based on the available design information. The results of this comparison exercise are also presented in this paper.

  5. 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)

  6. Uranium recovery from low-level aqueous sources. [76 references

    Energy Technology Data Exchange (ETDEWEB)

    Kelmers, A.D.; Goeller, H.E.

    1981-03-01

    The aqueous sources of soluble uranium were surveyed and evaluated in terms of the uranium geochemical cycle in an effort to identify potential unexploited resources. Freshwater sources appeared to be too low in uranium content to merit consideration, while seawater, although very dilute (approx. 3.3 ppB), contains approx. 4 x 10/sup 9/ metric tons of uranium in all the world's oceans. A literature review of recent publications and patents concerning uranium recovery from seawater was conducted. Considerable experimental work is currently under way in Japan; less is being done in the European countries. An assessment of the current state of technology is presented in this report. Repeated screening programs have identified hydrous titanium oxide as the most promising candidate absorbent. However, some of its properties such as distribution coefficient, selectivity, loading, and possibly stability appear to render its use inadequate in a practical recovery system. Also, various assessments of the energy efficiency of pumped or tidal power schemes for contacting the sorbent and seawater are in major disagreement. Needed future research and development tasks are discussed. A fundamental sorbent development program to greatly improve sorbent properties would be required to permit practical recovery of uranium from seawater. Major unresolved engineering aspects of such recovery systems are also identified and discussed.

  7. Medicina array demonstrator: calibration and radiation pattern characterization using a UAV-mounted radio-frequency source

    Science.gov (United States)

    Pupillo, G.; Naldi, G.; Bianchi, G.; Mattana, A.; Monari, J.; Perini, F.; Poloni, M.; Schiaffino, M.; Bolli, P.; Lingua, A.; Aicardi, I.; Bendea, H.; Maschio, P.; Piras, M.; Virone, G.; Paonessa, F.; Farooqui, Z.; Tibaldi, A.; Addamo, G.; Peverini, O. A.; Tascone, R.; Wijnholds, S. J.

    2015-06-01

    One of the most challenging aspects of the new-generation Low-Frequency Aperture Array (LFAA) radio telescopes is instrument calibration. The operational LOw-Frequency ARray (LOFAR) instrument and the future LFAA element of the Square Kilometre Array (SKA) require advanced calibration techniques to reach the expected outstanding performance. In this framework, a small array, called Medicina Array Demonstrator (MAD), has been designed and installed in Italy to provide a test bench for antenna characterization and calibration techniques based on a flying artificial test source. A radio-frequency tone is transmitted through a dipole antenna mounted on a micro Unmanned Aerial Vehicle (UAV) (hexacopter) and received by each element of the array. A modern digital FPGA-based back-end is responsible for both data-acquisition and data-reduction. A simple amplitude and phase equalization algorithm is exploited for array calibration owing to the high stability and accuracy of the developed artificial test source. Both the measured embedded element patterns and calibrated array patterns are found to be in good agreement with the simulated data. The successful measurement campaign has demonstrated that a UAV-mounted test source provides a means to accurately validate and calibrate the full-polarized response of an antenna/array in operating conditions, including consequently effects like mutual coupling between the array elements and contribution of the environment to the antenna patterns. A similar system can therefore find a future application in the SKA-LFAA context.

  8. GT0 Explosion Sources for IMS Infrasound Calibration: Charge Design and Yield Estimation from Near-source Observations

    Science.gov (United States)

    Gitterman, Y.; Hofstetter, R.

    2014-03-01

    Three large-scale on-surface explosions were conducted by the Geophysical Institute of Israel (GII) at the Sayarim Military Range, Negev desert, Israel: about 82 tons of strong high explosives in August 2009, and two explosions of about 10 and 100 tons of ANFO explosives in January 2011. It was a collaborative effort between Israel, CTBTO, USA and several European countries, with the main goal to provide fully controlled ground truth (GT0) infrasound sources, monitored by extensive observations, for calibration of International Monitoring System (IMS) infrasound stations in Europe, Middle East and Asia. In all shots, the explosives were assembled like a pyramid/hemisphere on dry desert alluvium, with a complicated explosion design, different from the ideal homogenous hemisphere used in similar experiments in the past. Strong boosters and an upward charge detonation scheme were applied to provide more energy radiated to the atmosphere. Under these conditions the evaluation of the actual explosion yield, an important source parameter, is crucial for the GT0 calibration experiment. Audio-visual, air-shock and acoustic records were utilized for interpretation of observed unique blast effects, and for determination of blast wave parameters suited for yield estimation and the associated relationships. High-pressure gauges were deployed at 100-600 m to record air-blast properties, evaluate the efficiency of the charge design and energy generation, and provide a reliable estimation of the charge yield. The yield estimators, based on empirical scaled relations for well-known basic air-blast parameters—the peak pressure, impulse and positive phase duration, as well as on the crater dimensions and seismic magnitudes, were analyzed. A novel empirical scaled relationship for the little-known secondary shock delay was developed, consistent for broad ranges of ANFO charges and distances, which facilitates using this stable and reliable air-blast parameter as a new potential

  9. ALPHACAL: A new user-friendly tool for the calibration of alpha-particle sources.

    Science.gov (United States)

    Timón, A Fernández; Vargas, M Jurado; Gallardo, P Álvarez; Sánchez-Oro, J; Peralta, L

    2018-02-01

    In this work, we present and describe the program ALPHACAL, specifically developed for the calibration of alpha-particle sources. It is therefore more user-friendly and less time-consuming than multipurpose codes developed for a wide range of applications. The program is based on the recently developed code AlfaMC, which simulates specifically the transport of alpha particles. Both cylindrical and point sources mounted on the surface of polished backings can be simulated, as is the convention in experimental measurements of alpha-particle sources. In addition to the efficiency calculation and determination of the backscattering coefficient, some additional tools are available to the user, like the visualization of energy spectrum, use of energy cut-off or low-energy tail corrections. ALPHACAL has been implemented in C++ language using QT library, so it is available for Windows, MacOs and Linux platforms. It is free and can be provided under request to the authors. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Portable, Solid-State Light Sources for Field Radiometric Calibrations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Various Earth Science fields require well-calibrated field radiometers whose calibrations must be tracked and verified in the field. NASA has long recognized...

  11. Portable, Solid-State Light Sources for Field Radiometric Calibrations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Various Earth Science fields require well-calibrated field radiometers whose calibrations must be tracked and verified in the field. NASA has long recognized the...

  12. Development of a UAV-mounted Light Source for Fluorescence Detector Calibration of the Telescope Array Experiment

    Science.gov (United States)

    Hayashi, Motoki; Tameda, Yuichiro; Tomida, Takayuki; Tsunesada, Yoshiki; Seki, Terutsugu; Saito, Yoshinori

    We are developing a unmanned aerial vehicle (UAV), which is called "Opt-copter", carrying a calibrated light source for fluorescence detector (FD) calibration of the Telescope Array (TA) experiment. Opt-copter is equipped with a high accuracy GPS device and a LED light source in the shape of a dodecahedron. A positioning accuracy of the GPS mounted on the UAV is 0.1 m, which meets the requirement for the calibration of the FDs at the distance of 100 m. The light source consists of 12 UV LEDs attached on each side of the dodecahedron, and it is covered with a spherical diffuser to improve the spatial uniformity of the light intensity. We report the status of Opt-copter development and the results of its test at the TA site.

  13. A Guide to Audio-Visual References: Selection and Ordering Sources.

    Science.gov (United States)

    Bonn, Thomas L., Comp.

    Audio-visual reference sources and finding guides to identify media for classroom utilization are compiled in this list of sources at State University of New York College at Cortland libraries. Citations with annotations and library locations are included under the subject headings: (1) general sources for all media formats; (2) reviews, guides,…

  14. A calibrator based on the use of low-coherent light source straightness interferometer and compensation method.

    Science.gov (United States)

    Lin, Shyh-Tsong; Yeh, Sheng-Lih; Chiu, Chi-Shang; Huang, Mou-Shan

    2011-10-24

    A calibrator utilizing a low-coherent light source straightness interferometer and a compensation method is introduced for straightness measurements in this paper. Where the interference pattern, which is modulated by an envelope function, generated by the interferometer undergoes a shifting as the Wolaston prism of the interferometer experiences a lateral displacement, and the compensation method senses the displacement by driving the prism back to the position to restore the pattern. A setup, which is with a measurement sensitivity of 36.6°/μm, constructed for realizing the calibrator is demonstrated. The experimental results from the uses of the setup reveal that the setup is with a measurement resolution and stability of 0.019 and 0.08 μm, respectively, validate the calibrator, and confirm the calibrator's applicability of straightness measurements and advantage of extensible working distance. © 2011 Optical Society of America

  15. Comprehensive inter-laboratory calibration of reference materials for delta O-18 versus VSMOW using various on-line high-temperature conversion techniques

    NARCIS (Netherlands)

    Brand, Willi A.; Coplen, Tyler B.; Aerts-Bijma, Anita T.; Böhlke, J.K.; Gehre, Matthias; Geilmann, Heike; Gröning, Manfred; Jansen, Henk G.; Meijer, Harro A. J.; Mroczkowski, Stanley J.; Qi, Haiping; Soergel, Karin; Stuart-Williams, Hilary; Weise, Stephan M.; Werner, Roland A.

    2009-01-01

    Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high-temperature conversion techniques (HTC)a in an evaluation sponsored by the International Union of Pure and

  16. Fourier transform holography with extended references using a coherent ultra-broadband light source

    NARCIS (Netherlands)

    Tenner, V.T.; Eikema, K.S.E.; Witte, S.M.

    2014-01-01

    We demonstrate a technique that enables lensless holographic imaging with extended reference structures, using ultra-broadband radiation sources for illumination. We show that this 'two-pulse imaging' approach works with one- and two-dimensional HERALDO reference structures, and demonstrate that the

  17. Method to calibrate an ionization chamber for measuring indoor radon concentrations with standard gamma-ray sources

    Science.gov (United States)

    Matsumoto, Yuzuru; Tokumori, Kenji; Iwata, Toru; Sakae, Takeji; Ishibashi, Kenji; Katase, Akira

    1989-06-01

    Most instruments for measuring radon concentrations in the air should be calibrated using air with known radon concentrations, obtained from a solution of radium. However, safe handling of such a solution of alpha-active elements can be troublesome. Standard gamma-ray sources of low activity are handled more safely and typically used to obtain the absolute detection efficiency of a Ge detector with high accuracy. A new method has been developed to calibrate a radon detector with such sources. A radon exhalation rate for a substance containing a small amount of radium is measured with the radon detector to be calibrated. After this, the vessel containing the radium is sealed so that the radon does not escape from it. The buildup of the activity of 214Bi in it is obtained from gamma-ray measurements and gives the radon exhalation rate on the basis of the activity of the standard sources. From the comparison between the two values of the exhalation rate, the radon detector is calibrated. A plane multiwire-electrode ionization chamber is used as a radon detector, and its detection efficiency is calculated from its geometrical form. The radon exhalation rate computed from the calculated efficiency agrees with that determined from the activity of the standard gamma-ray sources within their specified 6% error.

  18. Blackbody source in the -50 to +200 degrees C range for the calibration of radiometers and radiation thermometers.

    Science.gov (United States)

    Quinn, T J; Martin, J E

    1991-11-01

    A high-accuracy, large-aperture calibration source for radiometers and infrared radiation pyrometers operating in the range from -50 to +200 degrees C is described. It is shown that by means of reflecting surfaces inside the blackbody the requirements for temperature uniformity can be substantially relaxed while high accuracy in the characterization of the effectivet emperaturei s maintained.

  19. High dose rate 192Ir source calibration: A single institution experience

    Science.gov (United States)

    Abdullah, R.; Abdullah, N. H.; Mohamed, M.; Idris, N. R. N.; Yusoff, A. L.; Chen, S. C.; Zakaria, A.

    2017-05-01

    Measurement of source strength of new high dose rate (HDR) 192Ir supplied by the manufacturer is part of quality assurance recommended by Radiation Safety Section, Ministry of Health of Malaysia. The source strength is determined in reference air kerma rate (RAKR). The purpose of this study was to evaluate RAKR measurement of 192Ir using well-type ionisation chamber with RAKR stated in the certificate provided by the manufacturer. A retrospective study on 19 MicroSelectron HDR 192Ir Classic from 2001 to 2009 and 12 MicroSelectron HDR 192Ir V2 sources from 2009 to 2016 supplied by manufacturer were compared. From the study, the agreement between measured RAKR and RAKR stated in the certificate by manufacturer for all 32 sources supplied were within ±2.5%. As a conclusion, a threshold level of ±2.5% can be used as suitable indicator to spot problems of the brachytherapy system in Department of Nuclear Medicine Radiotherapy and Oncology, Hospital USM.

  20. A proficiency test system to improve performance of milk analysis methods and produce reference values for component calibration samples for infrared milk analysis.

    Science.gov (United States)

    Wojciechowski, Karen L; Melilli, Caterina; Barbano, David M

    2016-08-01

    Our goal was to determine the feasibility of combining proficiency testing, analytical method quality-assurance system, and production of reference samples for calibration of infrared milk analyzers to achieve a more efficient use of resources and reduce costs while maximizing analytical accuracy within and among milk payment-testing laboratories. To achieve this, we developed and demonstrated a multilaboratory combined proficiency testing and analytical method quality-assurance system as an approach to evaluate and improve the analytical performance of methods. A set of modified milks was developed and optimized to serve multiple purposes (i.e., proficiency testing, quality-assurance and method improvement, and to provide reference materials for calibration of secondary testing methods). Over a period of years, the approach has enabled the group of laboratories to document improved analytical performance (i.e., reduced within- and between-laboratory variation) of chemical reference methods used as the primary reference for calibration of high-speed electronic milk-testing equipment. An annual meeting of the laboratory technicians allows for review of results and discussion of each method and provides a forum for communication of experience and techniques that are of value to new analysts in the group. The monthly proficiency testing sample exchanges have the added benefit of producing all-laboratory mean reference values for a set of 14 milks that can be used for calibration, evaluation, and troubleshooting of calibration adjustment issues on infrared milk analyzers. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  1. 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.

  2. A primary standard for the measurement of alpha and beta particle surface emission rate from large area reference sources.

    Science.gov (United States)

    Ravindra, Anuradha; Kulkarni, D B; Joseph, Leena; Kulkarni, M S; Babu, D A R

    2016-01-01

    A large area windowless gas flow multi wire proportional counting system for the calibration of large area reference sources has been developed as a primary standard at Bhabha Atomic Research Centre (BARC). The counting system consists of a multi wire proportional counter (MWPC), vacuum system, gas flow system and pulse processing units. The MWPC detector assembly consists of a vacuum tight aluminum enclosure, multi wire grid and sliding source tray. Various detector characteristics like operating characteristics curve, Fe-55 spectrum for beta discriminator threshold setting and dead time of the measurement system were studied and determined in order to achieve an optimized detection capability. The surface emission rates of different source strengths were measured and their relative combined standard uncertainties were determined. Large Area Sources Comparison Exercise (LASCE) was organized by International Committee on Radionuclide Metrology (ICRM) working group and coordinated by National Institute for Ionising Radiation Metrology (ENEA), Italy, to demonstrate equivalence of surface emission rate measurements at the international platform. BARC participated in the programme and the results of LASCE are also discussed in this paper. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. A transportable source of gamma rays with discrete energies and wide range for calibration and on-site testing of gamma-ray detectors

    Science.gov (United States)

    Granja, Carlos; Slavicek, Tomas; Kroupa, Martin; Owens, Alan; Pospisil, Stanislav; Janout, Zdenek; Kralik, Miloslav; Solc, Jaroslav; Valach, Ondrej

    2015-01-01

    We describe a compact and transportable wide energy range, gamma-ray station for the calibration of gamma-ray sensitive devices. The station was specifically designed for the on-site testing and calibration of gamma-ray sensitive spacecraft payloads, intended for space flight on the BepiColombo and SoIar Orbiter missions of the European Space Agency. The source is intended to serve as a calibrated reference for post test center qualification of integrated payload instruments and for preflight evaluation of scientific radiation sensors. Discrete gamma rays in the energy range 100 keV-9 MeV are produced in the station with reasonable intensity using a radionuclide neutron source and 100 l of distilled water with 22 kg salt dissolved. The gamma-rays generated contain many discrete lines conveniently evenly distributed over the entire energy range. The neutron and gamma-ray fields have been simulated by Monte Carlo calculations. Results of the numerical calculations are given in the form of neutron and gamma-ray spectra as well as dose equivalent rate. The dose rate was also determined directly by dedicated dosemetric measurements. The gamma-ray field produced in the station was characterized using a conventional HPGe detector. The application of the station is demonstrated by measurements taken with a flight-qualified LaBr3:Ce scintillation detector. Gamma-ray spectra acquired by both detectors are presented. The minimum measuring times for calibration of the flight-version detector, was between 2 and 10 min (up to 6.2 MeV) and 20-30 min (up to 8 MeV), when the detector was placed at a distance 2-5 m from the station.

  4. 76 FR 19524 - Publication of Inflation Adjustment Factor, Nonconventional Source Fuel Credit, and Reference...

    Science.gov (United States)

    2011-04-07

    ... Internal Revenue Service Publication of Inflation Adjustment Factor, Nonconventional Source Fuel Credit...: Notice. SUMMARY: Publication of the inflation adjustment factor, nonconventional source fuel credit, and.... 45K). The inflation adjustment factor and reference price are used to determine the credit allowable...

  5. 78 FR 21008 - Publication of Inflation Adjustment Factor, Nonconventional Source Fuel Credit, and Reference...

    Science.gov (United States)

    2013-04-08

    ... Internal Revenue Service Publication of Inflation Adjustment Factor, Nonconventional Source Fuel Credit...: Notice. SUMMARY: Publication of the inflation adjustment factor, nonconventional source fuel credit, and.... 45K). The inflation adjustment factor and reference price are used to determine the credit allowable...

  6. Efficient Location of Research Reference Sources in the Field of Dance.

    Science.gov (United States)

    Kissinger, Pat; Jay, Danielle

    More than 45 basic dance reference research sources that would be useful to students, scholars, teachers, historians, and therapists are discussed in this bibliographic essay. Aspects of dance covered include choreography, criticism, teaching principles, aesthetic theory, dance therapy, and history. Sources are grouped by type: dictionaries and…

  7. Validation and calibration of various reference evapotranspiration alternative methods under the climate conditions of Bosnia and Herzegovina

    Directory of Open Access Journals (Sweden)

    Sabrija Čadro

    2017-12-01

    . Keywords: Reference Evapotranspiration, Limited data, FAO-56 Penman-Monteith, Calibration, Thornthwaite

  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. European Concerted Action on Anticoagulation. A multicentre calibration study of WHO international reference preparations for thromboplastin, rabbit (RBT/90) and human (rTF/95).

    Science.gov (United States)

    Poller, L; Keown, M; Chauhan, N; van den Besselaar, A M H P; Tripodi, A; Shiach, C; Jespersen, J

    2005-06-01

    A 10 centre calibration was performed after six years to determine the international sensitivity index (ISI) of rTF/95 relative to RBT/90, and to assess any international normalised ratio (INR) bias compared with the original multicentre calibration. After exclusion of one outlying centre, the follow up calibration gave a mean ISI for rTF/95 of 0.99, which although a small difference, is significantly greater than the mean ISI of 0.94 obtained previously. The change in ISI for international reference preparation (IRP) rTF/95 relative to RBT/90 would lead to a slight bias in INR for human compared with rabbit thromboplastins. At a theoretical INR of 3.0, the INR bias is 6.0%, and this is below the accepted 10% level of clinical relevance. Ongoing stability monitoring of World Health Organisation thromboplastin IRP is advised.

  10. Application of the reference method isotope dilution gas chromatography mass spectrometry (ID/GC/MS) to establish metrological traceability for calibration and control of blood glucose test systems.

    Science.gov (United States)

    Andreis, Elisabeth; Küllmer, Kai; Appel, Matthias

    2014-05-01

    Self-monitoring of blood glucose (BG) by means of handheld BG systems is a cornerstone in diabetes therapy. The aim of this article is to describe a procedure with proven traceability for calibration and evaluation of BG systems to guarantee reliable BG measurements. Isotope dilution gas chromatography mass spectrometry (ID/GC/MS) is a method that fulfills all requirements to be used in a higher-order reference measurement procedure. However, this method is not applicable for routine measurements because of the time-consuming sample preparation. A hexokinase method with perchloric acid (PCA) sample pretreatment is used in a measurement procedure for such purposes. This method is directly linked to the ID/GC/MS method by calibration with a glucose solution that has an ID/GC/MS-determined target value. BG systems are calibrated with whole blood samples. The glucose levels in such samples are analyzed by this ID/GC/MS-linked hexokinase method to establish traceability to higher-order reference material. For method comparison, the glucose concentrations in 577 whole blood samples were measured using the PCA-hexokinase method and the ID/GC/MS method; this resulted in a mean deviation of 0.1%. The mean deviation between BG levels measured in >500 valid whole blood samples with BG systems and the ID/GC/MS was 1.1%. BG systems allow a reliable glucose measurement if a true reference measurement procedure, with a noninterrupted traceability chain using ID/GC/MS linked hexokinase method for calibration of BG systems, is implemented. Systems should be calibrated by means of a traceable and defined measurement procedure to avoid bias. © 2014 Diabetes Technology Society.

  11. Intercomparison and calibration of dose calibrators used in nuclear medicine facilities

    CERN Document Server

    Costa, A M D

    2003-01-01

    The aim of this work was to establish a working standard for intercomparison and calibration of dose calibrators used in most of nuclear medicine facilities for the determination of the activity of radionuclides administered to patients in specific examinations or therapeutic procedures. A commercial dose calibrator, a set of standard radioactive sources, and syringes, vials and ampoules with radionuclide solutions used in nuclear medicine were utilized in this work. The commercial dose calibrator was calibrated for radionuclide solutions used in nuclear medicine. Simple instrument tests, such as linearity response and variation response with the source volume at a constant source activity concentration were performed. This instrument may be used as a reference system for intercomparison and calibration of other activity meters, as a method of quality control of dose calibrators utilized in nuclear medicine facilities.

  12. Calibration of a {sup 19} {sup 2}Ir source for high dose brachytherapy using various techniques; Calibracion de una fuente de {sup 192} Ir para braquiterapia de alta tasa de dosis mediante diversas tecnicas

    Energy Technology Data Exchange (ETDEWEB)

    Montilla Prieto, Tedicel C., E-mail: tcdicel@gmaiLcam [Instituto de Oncologia Dr. Miguel Perez Carreno, Barbula (Venezuela, Bolivarian Republic of). Departamento de Fisica y Dosimetria; Padron Rivero, Alvaro D., E-mail: alvarodpadronr@yahoo.com.ve [Universidad de Carabobo, Barbula (Venezuela, Bolivarian Republic of). Facultad de Ciencias de la Salud. Departamento de Ciencias Fisiologicas

    2013-10-01

    In this research we studied three experimental procedures for calibration of a source of {sup 192}Ir to high dose rate for clinical brachytherapy use, and thus were compared and analysis of the advantages and disadvantages of each. For this study we quantified the value of the current kerma rate reference in air by three procedures: source calibration using a well chamber, with an cylindrical ionization chamber in air, and a cylindrical ionization chamber on a phantom, and this magnitude was compared with the value provided by the manufacturer of the source and thereby obtaining the deviation corresponding . Thus, it was found that the deviation corresponding to the source calibration making use of a well chamber, remained within tolerance, while the cylindrical ionization chamber in air and on phantom exceeded the standards established in some documents. However, although both the measurement in air and in the phantom are the procedures for the final calibration source, these can be used to verify that the delivered dose are in tolerance.

  13. Comparing the biocidal properties of non-thermal plasma sources by reference protocol

    Science.gov (United States)

    Khun, Josef; Jirešová, Jana; Kujalová, Lucie; Hozák, Pavel; Scholtz, Vladimír

    2017-10-01

    The previously proposed reference protocol enabling easy comparison of biocidal properties of different non-thermal plasma sources has been followed and discussed. For inactivation tests the reference protocol has used spores of Gram positive bacterium Bacillus subtilis (ATCC 6633) deposited on a polycarbonate membrane as reference sample. In this work, biocidal properties of a negative glow corona, positive streamer corona, positive transient spark and cometary discharges are being compared in both open air and closed apparatus. Despite the total number of bacteria surviving 1 h exposure has decreased by up to 7 orders in closed apparatus, in open one, only weak inhibition bactericidal effect has been observed.

  14. Calibration of the E Si detector in a DE-E telescope with a ^212Pb pin source

    Science.gov (United States)

    Chan, Ka Pang

    2012-10-01

    In nuclear physics experiments, telescopes composed of two or more large area silicon strip detectors are used to identify charged particles. To use the energy loss method for particle identification, a thin (˜0.065mm) silicon detector (DE) is mounted in front of a thicker E detector (˜1.5 mm). The DE Si detector can be calibrated with 8.785, 6.778, 6.288, 5.685 and 5.423 MeV alpha particles emitted from a ^228Th source. However, this method cannot be used to calibrate the E detector as the alpha particles cannot penetrate the front DE detector. We have developed a method to calibrate the E detector by inserting a small irradiated dowel pin between the two Si detectors. The pin source is electroplated with ^212Pb nuclei which emit alpha particles with 8.785 MeV, 6.090 and 6.051 MeV. Insertion of the dowel pin is designed and guided so that the head of the pin lies near the center of the detector at a distance of 2.72 mm away from the surface of the E detector. In addition to providing two strong alpha peaks for calibrations, the close distance and high pixilation of the E detector allows accurate determination of the front dead layer of the E Si strip detector. This technique has been implemented successfully in calibrating the E Si detectors in the NSCL High Resolution Array (HiRA) consisting of 20 closely pack DE-E-CsI telescopes.

  15. A curvature calibrated bandgap reference with base—emitter current compensating in a 0.13 μm CMOS process

    Science.gov (United States)

    Zhuo, Ma; Xiaoqiang, Tan; Lunguo, Xie; Yang, Guo

    2010-11-01

    In bandgap references, the effect caused by the input offset of the operational amplifier can be effectively reduced by the utilization of cascade bipolar junction transistors (BJTs). But in modern CMOS logic processes, due to the small value of β, the base—emitter path of BJTs has a significant streaming effect on the collector current, which leads to a large temperature drift for the reference voltage. To solve this problem, a base—emitter current compensating technique is proposed in a cascade BJT bandgap reference structure to calibrate the curvature of the output voltage to temperature. Experimental results based on the 0.13 μm logic CMOS process show that the reference voltage is 1.238 V and the temperature coefficient is 6.2 ppm/°C within the range of -40 to 125 °C.

  16. A transportable source of gamma rays with discrete energies and wide range for calibration and on-site testing of gamma-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Granja, Carlos, E-mail: carlos.granja@utef.cvut.cz [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 12800 Prague 2 (Czech Republic); Slavicek, Tomas; Kroupa, Martin [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 12800 Prague 2 (Czech Republic); Owens, Alan [European Space Technology Centre ESTEC, European Space Agency ESA, Keplerlaan 1, 2200AG Noordwijk (Netherlands); Pospisil, Stanislav; Janout, Zdenek [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 12800 Prague 2 (Czech Republic); Kralik, Miloslav; Solc, Jaroslav [Czech Metrology Institute, Radiova 3, 102 00 Prague 10 (Czech Republic); Valach, Ondrej [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 12800 Prague 2 (Czech Republic)

    2015-01-21

    We describe a compact and transportable wide energy range, gamma-ray station for the calibration of gamma-ray sensitive devices. The station was specifically designed for the on-site testing and calibration of gamma-ray sensitive spacecraft payloads, intended for space flight on the BepiColombo and SoIar Orbiter missions of the European Space Agency. The source is intended to serve as a calibrated reference for post test center qualification of integrated payload instruments and for preflight evaluation of scientific radiation sensors. Discrete gamma rays in the energy range 100 keV–9 MeV are produced in the station with reasonable intensity using a radionuclide neutron source and 100 l of distilled water with 22 kg salt dissolved. The gamma-rays generated contain many discrete lines conveniently evenly distributed over the entire energy range. The neutron and gamma-ray fields have been simulated by Monte Carlo calculations. Results of the numerical calculations are given in the form of neutron and gamma-ray spectra as well as dose equivalent rate. The dose rate was also determined directly by dedicated dosemetric measurements. The gamma-ray field produced in the station was characterized using a conventional HPGe detector. The application of the station is demonstrated by measurements taken with a flight-qualified LaBr{sub 3}:Ce scintillation detector. Gamma-ray spectra acquired by both detectors are presented. The minimum measuring times for calibration of the flight-version detector, was between 2 and 10 min (up to 6.2 MeV) and 20–30 min (up to 8 MeV), when the detector was placed at a distance 2–5 m from the station. - Highlights: • Transportable station of mono-energetic gamma rays has been built. • Produced neutron and gamma ray field simulated by Monte Carlo calculations. • Discrete gamma rays produced in wide energy range up to 9 MeV. • Produced gamma ray spectra measured by HPGe and scintillating LaBr{sub 3}Ce detectors. • Demonstration of

  17. Herschel SPIRE FTS spectral line source calibrators

    DEFF Research Database (Denmark)

    Hopwood, Rosalind; Polehampton, Edward; Valtchanov, Ivan

    2015-01-01

    We present a summary of the Herschel SPIRE/FTS calibration programme to monitor the repeatability of spectral lines. Observations of planetary nebulae and post-AGB stars are used to assess repeatability and model the asymmetry of the instrument line shape....

  18. A certified urea reference material (NMIJ CRM 6006-a) as a reliable calibrant for the elemental analyses of amino acids and food samples.

    Science.gov (United States)

    Itoh, Nobuyasu; Yamazaki, Taichi; Sato, Ayako; Numata, Masahiko; Takatsu, Akiko

    2014-01-01

    We examined the reliability of a certified reference material (CRM) for urea (NMIJ CRM 6006-a) as a calibrant for N, C, and H in elemental analyzers. Only the N content for this CRM is provided as an indicative value. To estimate the C and H contents of the urea CRM, we took into account the purity of the urea and the presence of other identified impurities. When we examined the use of various masses of the calibrant (0.2 to 2 mg), we unexpectedly observed low signal intensities for small masses of H and N, but these plateaued at about 2 mg. We therefore analyzed four amino acid CRMs and four food CRMs on a 2-mg scale with the urea CRM as the calibrant. For the amino acid CRMs, the differences in the analytical and theoretical contents (≤0.0026 kg/kg) were acceptable with good repeatability (≤0.0013 kg/kg in standard deviation; n = 4). For food CRMs, comparable repeatabilities to those obtained with amino acid CRMs (≤0.0025 kg/kg in standard deviation; n = 4) were obtained. The urea CRM can therefore be used as a reliable calibrant for C, H, and N in an elemental analyzer.

  19. Inaccuracy of INR measurements and suggestions for improved WHO guidelines for calibration of reference preparations – a statistical study

    DEFF Research Database (Denmark)

    Attermann, Jørn

    2003-01-01

    %, when prediction is performed under the conventional WHO model. Under the same model the CV of the predicted vs. the true INR is believed to be only about 1% when it in reality is more than 4%. We suggest that the conventional calibration procedure is modified in order to reduce the twofold negative...... impact of lower true accuracy and overestimated reported accuracy on oral anticoagulant therapy and to allow for an unambiguous definition of true INR values....

  20. Analysis of reference sources used in drug-related Wikipedia articles.

    Science.gov (United States)

    Koppen, Laura; Phillips, Jennifer; Papageorgiou, Renee

    2015-07-01

    References from drug-related Wikipedia articles and a drug information database were compared. Drugs in Food and Drug Administration (FDA) MedWatch alerts from January-July 2013 were searched in Wikipedia and Lexicomp to compare reference types and to assess the time for drug safety information to be incorporated into Wikipedia articles. Wikipedia most commonly cited peer-reviewed journal articles (49.2%) and news articles (12.0%). MedWatch citations were incorporated into Wikipedia on average in 5.9 days. Wikipedia cited various sources but may not be a reliable, up-to-date resource for drug safety information.

  1. OPTICAL SPECTRA OF CANDIDATE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) FLAT-SPECTRUM RADIO SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Titov, O.; Stanford, Laura M. [Geoscience Australia, P.O. Box 378, Canberra, ACT 2601 (Australia); Johnston, Helen M.; Hunstead, Richard W. [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Pursimo, T. [Nordic Optical Telescope, Nordic Optical Telescope Apartado 474E-38700 Santa Cruz de La Palma, Santa Cruz de Tenerife (Spain); Jauncey, David L. [CSIRO Astronomy and Space Science, ATNF and Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Maslennikov, K. [Central Astronomical Observatory at Pulkovo, Pulkovskoye Shosse, 65/1, 196140, St. Petersburg (Russian Federation); Boldycheva, A., E-mail: oleg.titov@ga.gov.au [Ioffe Physical Technical Institute, 26 Polytekhnicheskaya, St. Petersburg, 194021 (Russian Federation)

    2013-07-01

    Continuing our program of spectroscopic observations of International Celestial Reference Frame (ICRF) sources, we present redshifts for 120 quasars and radio galaxies. Data were obtained with five telescopes: the 3.58 m European Southern Observatory New Technology Telescope, the two 8.2 m Gemini telescopes, the 2.5 m Nordic Optical Telescope (NOT), and the 6.0 m Big Azimuthal Telescope of the Special Astrophysical Observatory in Russia. The targets were selected from the International VLBI Service for Geodesy and Astrometry candidate International Celestial Reference Catalog which forms part of an observational very long baseline interferometry (VLBI) program to strengthen the celestial reference frame. We obtained spectra of the potential optical counterparts of more than 150 compact flat-spectrum radio sources, and measured redshifts of 120 emission-line objects, together with 19 BL Lac objects. These identifications add significantly to the precise radio-optical frame tie to be undertaken by Gaia, due to be launched in 2013, and to the existing data available for analyzing source proper motions over the celestial sphere. We show that the distribution of redshifts for ICRF sources is consistent with the much larger sample drawn from Faint Images of the Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying that the ultra-compact VLBI sources are not distinguished from the overall radio-loud quasar population. In addition, we obtained NOT spectra for five radio sources from the FIRST and NRAO VLA Sky Survey catalogs, selected on the basis of their red colors, which yielded three quasars with z > 4.

  2. Ultrasonic calibration and certification of V1 and V2 type reference standard blocks for use in Non-Destructive Testing

    Science.gov (United States)

    Maggi, L. E.; Silva, C. E. R.; Alvarenga, A. V.; Costa-Felix, R. P. B.

    2011-02-01

    Ultrasonic Non-Destructive Testing (US-NDT) has many industrial applications, such as flaws detection, welding integrity evaluation and solid material thickness measurement. To evaluate the instrumentation conditions, before a measurement begins, a "calibration" should be carried out with the aid of a reference standard block (RSB). Types V1 (ISO 2400) and V2 (ISO 7963) are the most widely used in US-NDT. Due their characteristics, V1 and V2 RSB can be classified as Reference Material, so that they can be certified, resulting in a Certified Reference Material (CRM). This paper describes technical aspects of a V1 and V2 RSB certification, based on ISO 2400, ISO 7963, EN 12223 and EN 27963. According the certification protocol established at Inmetro's Laboratory of Ultrasound, RSB relevant dimensions were determined through calibration. Ultrasound velocity was assessed by using a scope and a signal generator at 5 MHz. Uncertainties were determined including measurement accuracy under repeatability conditions. A complete uncertainty budget was determined for both parameters. Within the specimens used, velocities were in accordance with specifications 5920 ± 30 m/s.

  3. Absolute experimental and numerical calibration of the 14 MeV neutron source at the Frascati neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Angelone, M.; Pillon, M.; Batistoni, P.; Martini, M.; Martone, M.; Rado, V. [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, C.P. 65---00044 Frascati, Rome (Italy)

    1996-06-01

    The absolute neutron yield of the 14 MeV Frascati neutron generator (FNG) is routinely measured by means of the associated alpha-particle method with a silicon surface barrier detector (SSD). This paper describes the work carried out to characterize the neutron source in terms of absolute intensity and angle-energy distribution of the emitted neutrons. The development of the measuring setup and the assessment of the measurement results are also reported. A complementary calibration procedure for validating the SSD results, based on the use of fission chambers and the activation technique, is also reported. An accurate analysis of the system has been performed via the Monte Carlo neutron and photon MCNP transport code. A detailed model of the neutron source that includes ion slowing down has been inserted into the MCNP code to permit a numerical calibration of the neutron source for comparison with the experimental results. The resulting agreement among the various methods is very good considering the uncertainties, and an accuracy of {plus_minus}2{percent} is achieved for the measurement of the 14 MeV neutron yield of the FNG. {copyright} {ital 1996 American Institute of Physics.}

  4. Absolute experimental and numerical calibration of the 14 MeV neutron source at the Frascati neutron generator

    Science.gov (United States)

    Angelone, M.; Pillon, M.; Batistoni, P.; Martini, M.; Martone, M.; Rado, V.

    1996-06-01

    The absolute neutron yield of the 14 MeV Frascati neutron generator (FNG) is routinely measured by means of the associated alpha-particle method with a silicon surface barrier detector (SSD). This paper describes the work carried out to characterize the neutron source in terms of absolute intensity and angle-energy distribution of the emitted neutrons. The development of the measuring setup and the assessment of the measurement results are also reported. A complementary calibration procedure for validating the SSD results, based on the use of fission chambers and the activation technique, is also reported. An accurate analysis of the system has been performed via the Monte Carlo neutron and photon MCNP transport code. A detailed model of the neutron source that includes ion slowing down has been inserted into the MCNP code to permit a numerical calibration of the neutron source for comparison with the experimental results. The resulting agreement among the various methods is very good considering the uncertainties, and an accuracy of ±2% is achieved for the measurement of the 14 MeV neutron yield of the FNG.

  5. Xenon N4,500 Auger spectrum - a useful calibration source

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, T.X.; Bozek, J.D.; Kukk, E.; Myrseth, V.; Saethre, L.J.; Thomas, T.D.; Wiesner, Karoline

    2002-02-06

    In the xenon N4,5OO Auger spectrum there are 19 prominent lines ranging from 8 to 36 eV that provide a convenient set of standards for calibrating electron spectrometers. Combining optical data with recent measurements of this spectrum gives energies for these lines that are absolutely accurate to 11 meV. For most lines the relative accuracy is better than 1 meV; for a few it is about 3 meV. The spin-orbit splitting of the xenon 4d lines is measured to be 1979.0 +- 0.5meV.

  6. Generalized Reference Fields and Source Interpolation for the Difference Formulation of Radiation Transport

    Energy Technology Data Exchange (ETDEWEB)

    Luu, T C; Brooks, E D; Szoke, A

    2009-02-05

    In the difference formulation for the transport of thermally emitted photons, the photon intensity is defined relative to a reference field, the black body at the local material temperature. This choice of reference field combines the separate emission and absorption terms that nearly cancel, removing the dominant cause of noise in the Monte Carlo solution of thick systems, but introduces time and space derivative source terms that can not be determined until the end of the time step. The space derivative source term can also lead to noise induced crashes under certain conditions where the real physical photon intensity differs strongly from a black body at the local material temperature. In this paper, we consider a difference formulation relative to the material temperature at the beginning of the time step, or in cases where an alternative temperature better describes the radiation field, that temperature. The result is a method where iterative solution of the material energy equation is efficient and noise induced crashes are avoided. We couple our generalized reference field scheme with an ad hoc interpolation of the space derivative source, resulting in an algorithm that produces the correct flux between zones as the physical system approaches the thick limit.

  7. Comparison of the Equine Reference Sequence with Its Sanger Source Data and New Illumina Reads.

    Directory of Open Access Journals (Sweden)

    Jovan Rebolledo-Mendez

    Full Text Available The reference assembly for the domestic horse, EquCab2, published in 2009, was built using approximately 30 million Sanger reads from a Thoroughbred mare named Twilight. Contiguity in the assembly was facilitated using nearly 315 thousand BAC end sequences from Twilight's half brother Bravo. Since then, it has served as the foundation for many genome-wide analyses that include not only the modern horse, but ancient horses and other equid species as well. As data mapped to this reference has accumulated, consistent variation between mapped datasets and the reference, in terms of regions with no read coverage, single nucleotide variants, and small insertions/deletions have become apparent. In many cases, it is not clear whether these differences are the result of true sequence variation between the research subjects' and Twilight's genome or due to errors in the reference. EquCab2 is regarded as "The Twilight Assembly." The objective of this study was to identify inconsistencies between the EquCab2 assembly and the source Twilight Sanger data used to build it. To that end, the original Sanger and BAC end reads have been mapped back to this equine reference and assessed with the addition of approximately 40X coverage of new Illumina Paired-End sequence data. The resulting mapped datasets identify those regions with low Sanger read coverage, as well as variation in genomic content that is not consistent with either the original Twilight Sanger data or the new genomic sequence data generated from Twilight on the Illumina platform. As the haploid EquCab2 reference assembly was created using Sanger reads derived largely from a single individual, the vast majority of variation detected in a mapped dataset comprised of those same Sanger reads should be heterozygous. In contrast, homozygous variations would represent either errors in the reference or contributions from Bravo's BAC end sequences. Our analysis identifies 720,843 homozygous discrepancies

  8. Sayarim Infrasound Calibration Explosion: conducting, near-source and local observations

    Science.gov (United States)

    Gitterman, Y.; Hofstetter, A.

    2009-12-01

    The large-scale calibration explosion was successfully conducted by the Geophysical Institute of Israel at Sayarim Military Range on 26 August 2009 (detonation time 6:31:54.0 GMT, coordinates 30.00057°N, 34.81351°E). A charge of about 82 tons of HE explosives, assembled as a pyramid on the soft sediment surface, was detonated upwards. High-pressures and strong ground motions in the range 70-600 m were measured, and speed video recording was done. Preliminary analysis showed higher recorded peak pressures than estimated values, whereas the created crater and seismic magnitude (by Israel Seismic Network) were smaller than expected for this on-surface charge. These results confirm that the charge design provided necessary explosion energy generation and partition: maximum of the energy to the atmosphere and minimum to the ground. The primary goal of this calibration experiment was reached: infrasound signals were observed at numerous stations in Israel, the Mediterranean and Europe, including IMS stations, at distances up to 3500 km. We present here the charge design features, conducting procedures, the analysis of high-pressure, accelerometer and speed video recordings, and seismic and infrasound observations at Israel stations, in the range 0.1-360 km.

  9. Method for radiometric calibration of an endoscope's camera and light source

    Science.gov (United States)

    Rai, Lav; Higgins, William E.

    2008-03-01

    An endoscope is a commonly used instrument for performing minimally invasive visual examination of the tissues inside the body. A physician uses the endoscopic video images to identify tissue abnormalities. The images, however, are highly dependent on the optical properties of the endoscope and its orientation and location with respect to the tissue structure. The analysis of endoscopic video images is, therefore, purely subjective. Studies suggest that the fusion of endoscopic video images (providing color and texture information) with virtual endoscopic views (providing structural information) can be useful for assessing various pathologies for several applications: (1) surgical simulation, training, and pedagogy; (2) the creation of a database for pathologies; and (3) the building of patient-specific models. Such fusion requires both geometric and radiometric alignment of endoscopic video images in the texture space. Inconsistent estimates of texture/color of the tissue surface result in seams when multiple endoscopic video images are combined together. This paper (1) identifies the endoscope-dependent variables to be calibrated for objective and consistent estimation of surface texture/color and (2) presents an integrated set of methods to measure them. Results show that the calibration method can be successfully used to estimate objective color/texture values for simple planar scenes, whereas uncalibrated endoscopes performed very poorly for the same tests.

  10. A permeation-controlled formaldehyde reference source for application in environmental test chambers.

    Science.gov (United States)

    Salthammer, Tunga; Giesen, Ruth; Schripp, Tobias

    2017-10-01

    In a wide range of indoor air pollutants, formaldehyde is one of the most-used and best-known substances. In order to protect human health, many countries have established threshold values for the release of formaldehyde from miscellaneous products and revise them constantly. Compliance with these regulations is usually assessed by emission test chamber measurements or derived methods. To control and improve the mechanisms of an emission test chamber, a reliable reference source with sample mimicking emission properties is required but not available so far. This study describes a permeation-controlled reference source based on the application of paraformaldehyde as formaldehyde releasing polymeric compound. Interactions between the formaldehyde release of the source and the governing chamber parameters temperature, relative humidity and air velocity were investigated in 1 m(3) emission chambers. Depending on the conditions, constant formaldehyde concentrations between approximately 10 ppb and 150 ppb can be adjusted for up to 600 h. A linear correlation between the logarithm of the chamber concentration and the reciprocal temperature was found. The results support the feasibility of the source for validation of emission test chamber performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Improvement in the practical implementation of neutron source strength calibration using prompt gamma rays.

    Science.gov (United States)

    Khabaz, Rahim; Rene Vega-Carrillo, Hector

    2013-08-01

    In this study, the neutron emission rate from neutron sources using prompt gamma rays in hydrogen was determined, and several improvements were applied. Using Monte Carlo calculations, the best positions for the source, moderator and detector relative to each other were selected. For (241)Am-Be and (252)Cf sources, the sizes for polyethylene spheres with the highest efficiency were 12- and 10-inch, respectively. In addition, a new shielding cone was designed to account for scattered neutrons and gamma rays. The newly designed shielding cone, which is 45 cm in length, provided suitable attenuation for the source radiation. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  12. Calibration of Rainfall-Runoff Model by Referring to Hydrological Separation of Runoff Components using Chemical and Isotopic Characteristics of Discharge

    Science.gov (United States)

    Chikamori, H.

    2008-12-01

    Calibration of Rainfall-Runoff Model by Referring to Hydrological Separation of Runoff Components using Chemical and Isotopic Characteristics of Discharge Hidetaka Chikamori Graduate School of Environmental Science, Okayama University, JAPAN A rainfall-runoff model is generally calibrated by minimizing error in calculated runoff using records of hydrological components, that is, observed rainfall, discharge and observed or estimated evapotranpiration. However, calibration using only hydrological components sometimes produces a model with strange structure that does not reflect physical properties of an objective basin. It is probably due to error in referred hydrological records. In this study, the author calibrated a rainfall runoff model using not only hydrological record but also chemical and isotopic data of discharge so as to obtain a reasonably structured model from multiple viewpoints. Besides, the model structure was improved in order to simulate isotopic characteristics well. It is well known that ratio of surface flow in total flow can be estimated by change in concentration of cation or anion. Relative concentration of 18O, δ18O is well used for separating runoff of retained water in soil as "old water" from total runoff. A Long-and-Short Term Tank Model (LST2 Model) was applied to three Hinoki Cypress catchments in Mie experimental basin located in the middle of Japan. One of these catchments is of well-maintained planted forest, and two are of poor-maintained planted. A model was calibrated by Differential Evolution for each catchment using hydrological data, concentration of K+ and δ18O. In these catchments, Gomi et al (2008) showed that concentration of K+ well expresses ratio of surface runoff to total runoff, and that δ18O subsurface runoff to total runoff. The results show that an original version of LST2 Model cannot simulated delayed subsurface flow ratio estimated by δ18O, although it well simulates surface flow ratio estimated by

  13. Application of advanced shearing techniques to the calibration of autocollimators with small angle generators and investigation of error sources.

    Science.gov (United States)

    Yandayan, T; Geckeler, R D; Aksulu, M; Akgoz, S A; Ozgur, B

    2016-05-01

    The application of advanced error-separating shearing techniques to the precise calibration of autocollimators with Small Angle Generators (SAGs) was carried out for the first time. The experimental realization was achieved using the High Precision Small Angle Generator (HPSAG) of TUBITAK UME under classical dimensional metrology laboratory environmental conditions. The standard uncertainty value of 5 mas (24.2 nrad) reached by classical calibration method was improved to the level of 1.38 mas (6.7 nrad). Shearing techniques, which offer a unique opportunity to separate the errors of devices without recourse to any external standard, were first adapted by Physikalisch-Technische Bundesanstalt (PTB) to the calibration of autocollimators with angle encoders. It has been demonstrated experimentally in a clean room environment using the primary angle standard of PTB (WMT 220). The application of the technique to a different type of angle measurement system extends the range of the shearing technique further and reveals other advantages. For example, the angular scales of the SAGs are based on linear measurement systems (e.g., capacitive nanosensors for the HPSAG). Therefore, SAGs show different systematic errors when compared to angle encoders. In addition to the error-separation of HPSAG and the autocollimator, detailed investigations on error sources were carried out. Apart from determination of the systematic errors of the capacitive sensor used in the HPSAG, it was also demonstrated that the shearing method enables the unique opportunity to characterize other error sources such as errors due to temperature drift in long term measurements. This proves that the shearing technique is a very powerful method for investigating angle measuring systems, for their improvement, and for specifying precautions to be taken during the measurements.

  14. Selecting Sources that Define a Stable Celestial Reference Frame with the Allan Variance

    Science.gov (United States)

    Le Bail, Karine; Gordon, David; Ma, Chopo

    2016-12-01

    The ICRF2 was adopted by the IAU in 2009 and was based on the positions of 3,414 radio sources determined by VLBI. Discussions on the next realization of the ICRF (ICRF3) have been underway within the IAU and IVS since 2012. VLBI has made significant advances since ICRF2. From the latest GSFC solution, we extract a set of sources that defines a stable celestial reference frame, as shown by Feissel-Vernier 2003 te{Feissel-Vernier2003} using tools such as the Allan variance and the drift of the position time series. This method also allows us to highlight a set of the least stable sources that may need special handling.

  15. Comprehensive inter-laboratory calibration of reference materials for δ18O versus VSMOW using various on-line high-temperature conversion techniques

    Science.gov (United States)

    Brand, Willi A.; Coplen, Tyler B.; Aerts-Bijma, Anita T.; Bohlke, John Karl; Gehre, Matthias; Geilmann, Heike; Groning, Manfred; Jansen, Henk G.; Meijer, Harro A. J.; Mroczkowski, Stanley J.; Qi, Haiping; Soergel, Karin; Stuart-Williams, Hilary; Weise, Stephan M.; Werner, Roland A.

    2009-01-01

    Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high-temperature conversion techniques (HTC) in an evaluation sponsored by the International Union of Pure and Applied Chemistry (IUPAC). To aid in the calibration of these reference materials, which span more than 125‰, an artificially enriched reference water (δ18O of +78.91‰) and two barium sulfates (one depleted and one enriched in 18O) were prepared and calibrated relative to VSMOW2 and SLAP reference waters. These materials were used to calibrate the other isotopic reference materials in this study, which yielded:Reference materialδ18O and estimated combined uncertainty IAEA-602 benzoic acid+71.28 ± 0.36‰USGS35 sodium nitrate+56.81 ± 0.31‰IAEA-NO-3 potassium nitrate+25.32 ± 0.29‰IAEA-601 benzoic acid+23.14 ± 0.19‰IAEA-SO-5 barium sulfate+12.13 ± 0.33‰NBS 127 barium sulfate+8.59 ± 0.26‰VSMOW2 water0‰IAEA-600 caffeine−3.48 ± 0.53‰IAEA-SO-6 barium sulfate−11.35 ± 0.31‰USGS34 potassium nitrate−27.78 ± 0.37‰SLAP water−55.5‰The seemingly large estimated combined uncertainties arise from differences in instrumentation and methodology and difficulty in accounting for all measurement bias. They are composed of the 3-fold standard errors directly calculated from the measurements and provision for systematic errors discussed in this paper. A primary conclusion of this study is that nitrate samples analyzed for δ18O should be analyzed with internationally distributed isotopic nitrates, and likewise for sulfates and organics. Authors reporting relative differences of oxygen-isotope ratios (δ18O) of nitrates, sulfates, or organic material should explicitly state in their reports the δ18O values of two or more internationally distributed nitrates (USGS34, IAEA-NO-3, and USGS35), sulfates (IAEA-SO-5, IAEA

  16. Radioactive standards and calibration methods for contamination monitoring instruments

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Makoto [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-06-01

    Contamination monitoring in the facilities for handling unsealed radioactive materials is one of the most important procedures for radiation protection as well as radiation dose monitoring. For implementation of the proper contamination monitoring, radiation measuring instruments should not only be suitable to the purpose of monitoring, but also be well calibrated for the objective qualities of measurement. In the calibration of contamination monitoring instruments, quality reference activities need to be used. They are supplied in different such as extended sources, radioactive solutions or radioactive gases. These reference activities must be traceable to the national standards or equivalent standards. On the other hand, the appropriate calibration methods must be applied for each type of contamination monitoring instruments. In this paper, the concepts of calibration for contamination monitoring instruments, reference sources, determination methods of reference quantities and practical calibration methods of contamination monitoring instruments, including the procedures carried out in Japan Atomic Energy Research Institute and some relevant experimental data. (G.K.)

  17. Water vapor as an error source in microwave geodetic systems: Background and survey of calibration techniques. [very long base interferometry

    Science.gov (United States)

    Claflin, E. S.; Resch, G. M.

    1980-01-01

    Water vapor as an error source in radio interferometry systems is briefly examined. At microwave frequencies, the delay imposed by tropospheric water vapor becomes a limiting error source for high accuracy geodetic systems. The mapping of tropospheric induced errors into 'solved-for' parameters depends upon baseline length and observing strategy. Simulation analysis (and experience) indicates that in some cases, errors in estimating tropospheric delay can be magnified in their effect on baseline components. The various techniques by which tropospheric water can be estimated or measured are surveyed with particular consideration to their possible use as a calibration technique in support to very long baseline interferometry experiments. The method of remote sensing using a microwave radiometer seems to be the most effective way to provide an accurate estimate of water vapor delay.

  18. Operational Experience with Radioactive Source Calibration of the CMS Hadron Endcap Calorimeter Wedges with Phase I Upgrade Electronics

    CERN Document Server

    Bilki, Burak

    2017-01-01

    The Phase I Upgrade of the CMS Hadron Endcap Calorimeters consists of new photodetectors and front-end electronics. The upgrade will allow the elimination of the high amplitude noise and drifting response of the Hybrid Photo-Diodes, at the same time enabling the mitigation of the radiation damage of the scintillators and the wavelength shifting fibers with a larger spectral acceptance of the Silicon Photomultipliers. The upgrade will also allow increasing the longitudinal segmentation of the readout to be beneficial for pile-up mitigation and recalibration due to depth-dependent radiation damage. As a realistic operational exercise, the responses of the Hadron Endcap Calorimeter wedges were calibrated with a 60Co radioactive source both with current and upgrade electronics. The exercise provided significant experience towards the full upgrade during the Year End Technical Stop 2017-2018. Here we describe the instrumentation details and the operational experiences related to the sourcing exercise.

  19. Calibration of the nonlinear ring model at the Diamond Light Source

    CERN Document Server

    Bartolini, R; Rehm, G; Martin, I P S

    2011-01-01

    Nonlinear beam dynamics plays a crucial role in defining the performance of a storage ring. The beam lifetime, the injection efficiency, and the dynamic and momentum apertures available to the beam are optimized during the design phase by a proper optimization of the linear lattice and of the distribution of sextupole families. The correct implementation of the design model, especially the nonlinear part, is a nontrivial accelerator physics task. Several parameters of the nonlinear dynamics can be used to compare the real machine with the model and eventually to correct the accelerator. Most of these parameters are extracted from the analysis of turn-by-turn data after the excitation of betatron oscillations of the particles in the ring. We present the experimental results of the campaign of measurements carried out at the Diamond storage ring to characterize the nonlinear beam dynamics. A combination of frequency map analysis with the detuning with momentum measurements has allowed for a precise calibration ...

  20. VCSEL-based calibration-free carbon monoxide sensor at 2.3 μm with in-line reference cell

    Science.gov (United States)

    Chen, J.; Hangauer, A.; Strzoda, R.; Amann, M.-C.

    2011-02-01

    A compact and calibration-free carbon monoxide sensor approach utilizing the wide current-tunability of 2.3 μm VCSELs is reported. A separate reference cell is avoided by filling the reference gas (methane) in the photodetector housing. By applying bandwidth optimized wide/narrow wavelength scan concept, inherent wavelength scale calibration and self-monitoring of the sensor are realized, with which the laser aging process is also under control. An efficient linear least-squares curve fit using an analytical signal model for the narrow scan spectrum is done, utilizing the knowledge of the absolute wavelength scale and also the estimated WMS modulation amplitude obtained from the wide scan. The scan width of the narrow spectrum is optimized aiming at the maximum signal to noise ratio on the determined CO concentration. These concepts are universal and can be utilized for optical sensing of other gases as well and the sensor was tested under diverse applications e.g. fire detection and combustion optimization.

  1. Applications of an 88Y/Be photoneutron calibration source to dark matter and neutrino experiments.

    Science.gov (United States)

    Collar, J I

    2013-05-24

    The low-energy monochromatic neutron emission from an (88)Y/Be source can be exploited to mimic the few keV(nr) nuclear recoils expected from low-mass weakly interacting massive particles and coherent scattering of neutrinos off nuclei. Using this source, a experiment, resulting in a marked increase of its tension with other searches, under the standard set of phenomenological assumptions. The method is illustrated for other target materials (superheated and noble liquids).

  2. Using structural equation modeling to construct calibration equations relating PM2.5 mass concentration samplers to the federal reference method sampler

    Science.gov (United States)

    Bilonick, Richard A.; Connell, Daniel P.; Talbott, Evelyn O.; Rager, Judith R.; Xue, Tao

    2015-02-01

    concentration measurements made by seven collocated samplers at an urban monitoring site in Pittsburgh, Pennsylvania, were used. These samplers, which included three federal reference method (FRM) samplers, three speciation samplers, and a tapered element oscillating microbalance (TEOM), operated at various times during the 10-year PARIES study period. Because TEOM measurements are known to depend on temperature, the constructed SEM provided calibration equations relating the TEOM to the FRM and speciation samplers as a function of ambient temperature. It was shown that TEOM imprecision and TEOM bias (relative to the FRM) both decreased as temperature increased. It also was shown that the temperature dependency for bias was non-linear and followed a sigmoidal (logistic) pattern. The speciation samplers exhibited only small bias relative to the FRM samplers, although the FRM samplers were shown to be substantially more precise than both the TEOM and the speciation samplers. Comparison of the SEM results to pairwise simple linear regression results showed that the regression results can differ substantially from the correctly-derived calibration equations, especially if the less-precise device is used as the independent variable in the regression.

  3. Calibration of the nonlinear ring model at the Diamond Light Source

    Directory of Open Access Journals (Sweden)

    R. Bartolini

    2011-05-01

    Full Text Available Nonlinear beam dynamics plays a crucial role in defining the performance of a storage ring. The beam lifetime, the injection efficiency, and the dynamic and momentum apertures available to the beam are optimized during the design phase by a proper optimization of the linear lattice and of the distribution of sextupole families. The correct implementation of the design model, especially the nonlinear part, is a nontrivial accelerator physics task. Several parameters of the nonlinear dynamics can be used to compare the real machine with the model and eventually to correct the accelerator. Most of these parameters are extracted from the analysis of turn-by-turn data after the excitation of betatron oscillations of the particles in the ring. We present the experimental results of the campaign of measurements carried out at the Diamond storage ring to characterize the nonlinear beam dynamics. A combination of frequency map analysis with the detuning with momentum measurements has allowed for a precise calibration of the nonlinear model that can accurately reproduce the nonlinear beam dynamics in Diamond.

  4. In situ calibration of a light source in a sensor device

    Energy Technology Data Exchange (ETDEWEB)

    Okandan, Murat; Serkland, Darwin k.; Merchant, Bion J.

    2015-12-29

    A sensor device is described herein, wherein the sensor device includes an optical measurement system, such as an interferometer. The sensor device further includes a low-power light source that is configured to emit an optical signal having a constant wavelength, wherein accuracy of a measurement output by the sensor device is dependent upon the optical signal having the constant wavelength. At least a portion of the optical signal is directed to a vapor cell, the vapor cell including an atomic species that absorbs light having the constant wavelength. A photodetector captures light that exits the vapor cell, and generates an electrical signal that is indicative of intensity of the light that exits the vapor cell. A control circuit controls operation of the light source based upon the electrical signal, such that the light source emits the optical signal with the constant wavelength.

  5. A curved crystal spectrometer for energy calibration and spectral characterization of mammographic x-ray sources.

    Science.gov (United States)

    Hudson, L T; Deslattes, R D; Henins, A; Chantler, C T; Kessler, E G; Schweppe, J E

    1996-10-01

    Clinical efficacy of diagnostic radiology for mammographic examinations is critically dependent on source characteristics, detection efficiency, image resolution and applied high voltage. In this report we focus on means for evaluation of source-dependent issues including noninvasive determination of the applied high voltage, and characterization of intrinsic spectral distributions which in turn reflect the effects of added filtration and target and window contamination. It is shown that a particular form of x-ray curved crystal spectrometry with electronic imaging can serve to determine all relevant parameters within the confines of a standard clinical exposure.

  6. A multi-source satellite data approach for modelling Lake Turkana water level: calibration and validation using satellite altimetry data

    Directory of Open Access Journals (Sweden)

    N. M. Velpuri

    2012-01-01

    Full Text Available Lake Turkana is one of the largest desert lakes in the world and is characterized by high degrees of inter- and intra-annual fluctuations. The hydrology and water balance of this lake have not been well understood due to its remote location and unavailability of reliable ground truth datasets. Managing surface water resources is a great challenge in areas where in-situ data are either limited or unavailable. In this study, multi-source satellite-driven data such as satellite-based rainfall estimates, modelled runoff, evapotranspiration, and a digital elevation dataset were used to model Lake Turkana water levels from 1998 to 2009. Due to the unavailability of reliable lake level data, an approach is presented to calibrate and validate the water balance model of Lake Turkana using a composite lake level product of TOPEX/Poseidon, Jason-1, and ENVISAT satellite altimetry data. Model validation results showed that the satellite-driven water balance model can satisfactorily capture the patterns and seasonal variations of the Lake Turkana water level fluctuations with a Pearson's correlation coefficient of 0.90 and a Nash-Sutcliffe Coefficient of Efficiency (NSCE of 0.80 during the validation period (2004–2009. Model error estimates were within 10% of the natural variability of the lake. Our analysis indicated that fluctuations in Lake Turkana water levels are mainly driven by lake inflows and over-the-lake evaporation. Over-the-lake rainfall contributes only up to 30% of lake evaporative demand. During the modelling time period, Lake Turkana showed seasonal variations of 1–2 m. The lake level fluctuated in the range up to 4 m between the years 1998–2009. This study demonstrated the usefulness of satellite altimetry data to calibrate and validate the satellite-driven hydrological model for Lake Turkana without using any in-situ data. Furthermore, for Lake Turkana, we identified and outlined opportunities and challenges of using a calibrated

  7. A multi-source satellite data approach for modelling Lake Turkana water level: calibration and validation using satellite altimetry data

    Science.gov (United States)

    Velpuri, N. M.; Senay, G. B.; Asante, K. O.

    2012-01-01

    Lake Turkana is one of the largest desert lakes in the world and is characterized by high degrees of inter- and intra-annual fluctuations. The hydrology and water balance of this lake have not been well understood due to its remote location and unavailability of reliable ground truth datasets. Managing surface water resources is a great challenge in areas where in-situ data are either limited or unavailable. In this study, multi-source satellite-driven data such as satellite-based rainfall estimates, modelled runoff, evapotranspiration, and a digital elevation dataset were used to model Lake Turkana water levels from 1998 to 2009. Due to the unavailability of reliable lake level data, an approach is presented to calibrate and validate the water balance model of Lake Turkana using a composite lake level product of TOPEX/Poseidon, Jason-1, and ENVISAT satellite altimetry data. Model validation results showed that the satellite-driven water balance model can satisfactorily capture the patterns and seasonal variations of the Lake Turkana water level fluctuations with a Pearson's correlation coefficient of 0.90 and a Nash-Sutcliffe Coefficient of Efficiency (NSCE) of 0.80 during the validation period (2004-2009). Model error estimates were within 10% of the natural variability of the lake. Our analysis indicated that fluctuations in Lake Turkana water levels are mainly driven by lake inflows and over-the-lake evaporation. Over-the-lake rainfall contributes only up to 30% of lake evaporative demand. During the modelling time period, Lake Turkana showed seasonal variations of 1-2 m. The lake level fluctuated in the range up to 4 m between the years 1998-2009. This study demonstrated the usefulness of satellite altimetry data to calibrate and validate the satellite-driven hydrological model for Lake Turkana without using any in-situ data. Furthermore, for Lake Turkana, we identified and outlined opportunities and challenges of using a calibrated satellite-driven water

  8. A multi-source satellite data approach for modelling Lake Turkana water level: Calibration and validation using satellite altimetry data

    Science.gov (United States)

    Velpuri, N.M.; Senay, G.B.; Asante, K.O.

    2012-01-01

    Lake Turkana is one of the largest desert lakes in the world and is characterized by high degrees of interand intra-annual fluctuations. The hydrology and water balance of this lake have not been well understood due to its remote location and unavailability of reliable ground truth datasets. Managing surface water resources is a great challenge in areas where in-situ data are either limited or unavailable. In this study, multi-source satellite-driven data such as satellite-based rainfall estimates, modelled runoff, evapotranspiration, and a digital elevation dataset were used to model Lake Turkana water levels from 1998 to 2009. Due to the unavailability of reliable lake level data, an approach is presented to calibrate and validate the water balance model of Lake Turkana using a composite lake level product of TOPEX/Poseidon, Jason-1, and ENVISAT satellite altimetry data. Model validation results showed that the satellitedriven water balance model can satisfactorily capture the patterns and seasonal variations of the Lake Turkana water level fluctuations with a Pearson's correlation coefficient of 0.90 and a Nash-Sutcliffe Coefficient of Efficiency (NSCE) of 0.80 during the validation period (2004-2009). Model error estimates were within 10% of the natural variability of the lake. Our analysis indicated that fluctuations in Lake Turkana water levels are mainly driven by lake inflows and over-the-lake evaporation. Over-the-lake rainfall contributes only up to 30% of lake evaporative demand. During the modelling time period, Lake Turkana showed seasonal variations of 1-2m. The lake level fluctuated in the range up to 4m between the years 1998-2009. This study demonstrated the usefulness of satellite altimetry data to calibrate and validate the satellite-driven hydrological model for Lake Turkana without using any in-situ data. Furthermore, for Lake Turkana, we identified and outlined opportunities and challenges of using a calibrated satellite-driven water balance

  9. A new scanning system for alpha decay events as calibration sources for range-energy relation in nuclear emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, J., E-mail: jyoshida@gifu-u.ac.jp; Kinbara, S.; Mishina, A.; Nakazawa, K.; Soe, M.K.; Theint, A.M.M.; Tint, K.T.

    2017-03-01

    A new scanning system named “Vertex picker” has been developed to rapid collect alpha decay events, which are calibration sources for the range-energy relation in nuclear emulsion. A computer-controlled optical microscope scans emulsion layers exhaustively, and a high-speed and high-resolution camera takes their micrographs. A dedicated image processing picks out vertex-like shapes. Practical operations of alpha decay search were demonstrated by emulsion sheets of the KEK-PS E373 experiment. Alpha decays of nearly 28 events were detected in eye-check work on a PC monitor per hour. This yield is nearly 20 times more effective than that by the conventional eye-scan method. The speed and quality is acceptable for the coming new experiment, J-PARC E07.

  10. Operational Experience with Radioactive Source Calibration of the CMS Hadron Endcap Calorimeter Wedges with Phase I Upgrade Electronics

    CERN Document Server

    Bilki, Burak

    2017-01-01

    The Phase I Upgrade of the CMS Hadron Endcap Calorimeters consist of new photodetectors (Silicon Photomultipliers in place of Hybrid Photo-Diodes) and front-end electronics (QIE11). The upgrade will allow the elimination of the high amplitude noise and drifting response of the Hybrid Photo-Diodes, at the same time enabling the mitigation of the radiation damage of the scintillators and the wavelength shifting fibers with a larger spectral acceptance of the Silicon Photomultipliers. The upgrade will also allow to increase the longitudinal segmentation of the readout to be beneficial for pile-up mitigation and recalibration due to depth-dependent radiation damage.As a realistic operational exercise, the responses of the Hadron Endcap Calorimeter wedges are being calibrated with a $^{60}$Co radioactive source both with current and upgrade electronics. The exercise will provide a manifestation of the benefits of the upgrade. Here we describe the instrumentation details and the operational experiences related to t...

  11. Optical counterpart positions of extragalactic radio sources and connecting optical and radio reference frames

    Science.gov (United States)

    Aslan, Z.; Gumerov, R.; Jin, W.; Khamitov, I.; Maigurova, N.; Pinigin, G.; Tang, Z.; Wang, S.

    2010-01-01

    We discuss the results of an investigation of astrometric positions of extragalactic radio sources from a list for the International Celestial Reference Frame. About 300 fields around extragalactic radio sources were observed during the years 2000-2003. The observations were performed mainly using two telescopes equipped with CCD cameras at TUG, Turkey (Russian-Turkish Telescope - RTT150) and at YAO (1 m telescope), (Kunming, China). The mean accuracies of the measured positions are 38 mas in right ascension and 35 mas in declination. A comparison between the measured optical positions determined using the UCAC2 catalog and the radio positions from the current ICRF shows that the overall optical-minus- radio offsets are -4 and +15 mas for right ascension and declination, respectively. The formal internal errors of these mean offsets are 4 mas. The results of optical positions with respect to the reference catalogue 2MASS are also given. A search for a relation between optical and radio reference frames indicates that the orientation angles are near zero within their accuracy of about 5 mas. The link accuracy becomes 3 mas when our observations are combined with other studies. Tables 2 and 3 giving the positions are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/510/A10Present address: İstanbul Kültür University, Ataköy Yerleşkesi, 34156 Istanbul, Turkey

  12. Basic poly(propylene glycols) as reference compounds for internal mass calibration in positive-ion matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Gross, Jürgen H

    2017-12-01

    Basic poly(propylene glycols), commercially available under the trade name Jeffamine, are evaluated for their potential use as internal mass calibrants in matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry. Due to their basic amino endgroups Jeffamines are expected to deliver [M+H] + ions in higher yields than neutral poly(propylene glycols) or poly(ethylene glycols). Aiming at accurate mass measurements and molecular formula determinations by matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry, four Jeffamines (M-600, M-2005, D-400, D-230) were thus compared. As a result, Jeffamine M-2005 is introduced as a new mass calibrant for positive-ion matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry in the range of m/z 200-1200 and the reference mass list is provided. While Jeffamine M-2005 is compatible with α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, and 2-[(2 E)-3-(4- tert-butylphenyl)-2-methylprop-2-enylidene]malonitrile matrix, its use in combination with 2-[(2 E)-3-(4- tert-butylphenyl)-2-methylprop-2-enylidene]malonitrile provides best results due to low laser fluence requirements. Applications to PEG 300, PEG 600, the ionic liquid trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl)-trifluorophosphate, and [60]fullerene demonstrate mass accuracies of 2-5 ppm.

  13. The Italian reference site for TEM methods

    Directory of Open Access Journals (Sweden)

    Vincenzo Sapia

    2015-11-01

    Full Text Available The success of a long term transient electromagnetic survey (TEM rigorously calls for appropriate system calibration, in addition to advanced processing and inversion of the measured data. In fact, acquisition of TEM data can be affected by a variety of noise sources from both inside and outside the system, making it difficult, for example, to define an absolute turn off time and/or to synchronize transmitter and receiver. For these reasons, a reference site plays an important role. As first step, we performed the calibration of a Geonics 47 at the Lyngby reference site in Denmark. We then set up a new reference site using the same calibrated TEM instrument. The reference site was established in the San Rossore park area (Pisa, where we identified an area that matches the required conditions. Subsequently, a series of TEM measurements were collected in the selected area using two pre-calibrated TEM instruments: the Geonics 47 and the WalkTEM respectively. The reference responses were therefore jointly inverted, obtaining a 5 layers model that was appointed to be the TEM reference model for the site. Afterwards, based on that reference model, we calibrated the Geonics 47 and 57 instruments for a 100 x 100 m central loop configuration. A unique time-shift and a data level shift factor was calculated and applied to the TEM system as result of the calibration procedure. The San Rossore TEM reference site is now available for anyone interested in calibrating TEM systems.

  14. Cannibalism in Latin-Greek sources: its references in mythology and ancient philosophy

    Directory of Open Access Journals (Sweden)

    Domingo F. Sanz

    2013-06-01

    Full Text Available This article tries to analyze and comment on the greater amount of references regarding the phenomenon of cannibalism that there exists in Greek and Latin literary tradition. After reviewing many of the sources, it is possible to distinguish the different ways in which this tradition approached such phenomenon and to discover a common intention: starting from the mythology or the Homeric epic, going through the different philosophical trends and schools of thought, we will begin to realize and conclude that in many occasions there is a use of the concept of cannibalism to negatively define «the other», the outcast or foreigner, opening thus a topic that still survives nowadays.

  15. Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) with Standard Reference Line for the Analysis of Stainless Steel.

    Science.gov (United States)

    Fu, Hongbo; Dong, Fengzhong; Wang, Huadong; Jia, Junwei; Ni, Zhibo

    2017-08-01

    In this work, calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is used to analyze a certified stainless steel sample. Due to self-absorption of the spectral lines from the major element Fe and the sparse lines of trace elements, it is usually not easy to construct the Boltzmann plots of all species. A standard reference line method is proposed here to solve this difficulty under the assumption of local thermodynamic equilibrium so that the same temperature value for all elements present into the plasma can be considered. Based on the concentration and rich spectral lines of Fe, the Stark broadening of Fe(I) 381.584 nm and Saha-Boltzmann plots of this element are used to calculate the electron density and the plasma temperature, respectively. In order to determine the plasma temperature accurately, which is seriously affected by self-absorption, a pre-selection procedure for eliminating those spectral lines with strong self-absorption is employed. Then, one spectral line of each element is selected to calculate its corresponding concentration. The results from the standard reference lines with and without self-absorption of Fe are compared. This method allows us to measure trace element content and effectively avoid the adverse effects due to self-absorption.

  16. Validation of modified milk reference sample in terms of its suitability for infra-red analysis calibration via evaluation of physical properties

    Directory of Open Access Journals (Sweden)

    Oto Hanuš

    2010-01-01

    Full Text Available Routine milk analyses using the efficient indirect infra-red method are important for the milk food chain quality. The reliability of the results depends on the calibration quality. It is important to use a relevant set of reference calibration samples (RCSs. RCSs with right range of values can be prepared using various methods. This paper was aimed to balance the impacts of dilution for decrease of main components in RCSs because of minimal change of matrix interference effects. Cow milk samples (MSs were diluted (4/1 using distilled water, NaCl solution and a solution with specific composition (SC; because of disturbance in the balance of the milk matrix (NaCl 1.145; KCl 0.849; K2HPO4 1.8463; citric acid 1.7; urea 0.3 g / l for reduction in main milk components. Fat (F, crude protein (CP, lactose (L, milk freezing point (MFP, osmolality (OS and electrical conductivity (EC were measured in all (original as well as modified MSs. The lowest MFP and OS were in the original milk −0.5559 °C and 274.5 mOsmol/kg. The MFP was increased to −0.4369 °C and osmolality decreased to 217.83 ­mOsmol/kg by the addition of water. The MFP was decreased (−0.4903 °C and returned to original milk value by the addition of NaCl solutin. MFP was −0.4788 °C due to SC addition. The decrease was less than for NaCl. The ability of other SC components (K2HPO4, KCl, citric acid and urea to MFP decrease is less than for NaCl solution. EC was highest for NaCl set 4.69 mS / cm, EC for SC was 4.48 mS / cm (P < 0.001. The original MSs set showed EC 4.27 mS / cm. The SC was the nearest to original MSs in terms of total mineral composition. ECs for both modifications differed (P < 0.001 from original MSs. The procedure is applicable for balance of interference effects of milk matrix because of relevant calibration.

  17. Estimating usual food intake distributions by using the multiple source method in the EPIC-Potsdam Calibration Study.

    Science.gov (United States)

    Haubrock, Jennifer; Nöthlings, Ute; Volatier, Jean-Luc; Dekkers, Arnold; Ocké, Marga; Harttig, Ulrich; Illner, Anne-Kathrin; Knüppel, Sven; Andersen, Lene F; Boeing, Heiner

    2011-05-01

    Estimating usual food intake distributions from short-term quantitative measurements is critical when occasionally or rarely eaten food groups are considered. To overcome this challenge by statistical modeling, the Multiple Source Method (MSM) was developed in 2006. The MSM provides usual food intake distributions from individual short-term estimates by combining the probability and the amount of consumption with incorporation of covariates into the modeling part. Habitual consumption frequency information may be used in 2 ways: first, to distinguish true nonconsumers from occasional nonconsumers in short-term measurements and second, as a covariate in the statistical model. The MSM is therefore able to calculate estimates for occasional nonconsumers. External information on the proportion of nonconsumers of a food can also be handled by the MSM. As a proof-of-concept, we applied the MSM to a data set from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam Calibration Study (2004) comprising 393 participants who completed two 24-h dietary recalls and one FFQ. Usual intake distributions were estimated for 38 food groups with a proportion of nonconsumers > 70% in the 24-h dietary recalls. The intake estimates derived by the MSM corresponded with the observed values such as the group mean. This study shows that the MSM is a useful and applicable statistical technique to estimate usual food intake distributions, if at least 2 repeated measurements per participant are available, even for food groups with a sizeable percentage of nonconsumers.

  18. The 2008 Wells, Nevada earthquake sequence: Source constraints using calibrated multiple event relocation and InSAR

    Science.gov (United States)

    Nealy, Jennifer; Benz, Harley M.; Hayes, Gavin; Berman, Eric; Barnhart, William

    2017-01-01

    The 2008 Wells, NV earthquake represents the largest domestic event in the conterminous U.S. outside of California since the October 1983 Borah Peak earthquake in southern Idaho. We present an improved catalog, magnitude complete to 1.6, of the foreshock-aftershock sequence, supplementing the current U.S. Geological Survey (USGS) Preliminary Determination of Epicenters (PDE) catalog with 1,928 well-located events. In order to create this catalog, both subspace and kurtosis detectors are used to obtain an initial set of earthquakes and associated locations. The latter are then calibrated through the implementation of the hypocentroidal decomposition method and relocated using the BayesLoc relocation technique. We additionally perform a finite fault slip analysis of the mainshock using InSAR observations. By combining the relocated sequence with the finite fault analysis, we show that the aftershocks occur primarily updip and along the southwestern edge of the zone of maximum slip. The aftershock locations illuminate areas of post-mainshock strain increase; aftershock depths, ranging from 5 to 16 km, are consistent with InSAR imaging, which shows that the Wells earthquake was a buried source with no observable near-surface offset.

  19. Determining the irradiance signal from an asymmetric source with directional detectors: application to calibrations of radiometers with diffusers.

    Science.gov (United States)

    Manninen, Pasi; Kärhä, Petri; Ikonen, Erkki

    2008-09-10

    The energy transfer integral between radiating rectangular and detecting circular parallel plates having nonideal angular characteristics is solved for modeling the distance dependence of the irradiance signal. The equation derived for the irradiance signal, which is called the modified inverse-square law, depends on the position, shape, size, and angular characteristics of the light source and the detector. We apply the new model equation to the calibration of a spectroradiometer to determine accurately the distance offsets, which fix the positions of the effective receiving apertures of diffusers used in the entrance optics of spectroradiometers. Earlier measurement results, e.g., for solar UV irradiance, may include uncorrected effects and can be corrected reliably as diffuser offsets and other correction factors are determined with the modified inverse-square law. Simplifications of the modified inverse-square law for analyzing the distance offsets and the correction factors are studied. Simplified equations for the diffuser offset analysis may be used without losing the accuracy when the cosine response of the diffuser is reasonably good. However, for diffusers whose angular responsivities deviate much from the cosinusoidal angular responsivity, large approximation errors in the diffuser offset values may appear if the angular effects are not properly taken into account.

  20. Off-axis reference beam for full-field swept-source OCT and holoscopy

    Science.gov (United States)

    Hillmann, Dierck; Spahr, Hendrik; Sudkamp, Helge; Hain, Carola; Hinkel, Laura; Franke, Gesa; Hüttmann, Gereon

    2017-10-01

    In numerous applications, Fourier-domain optical coherence tomography (FD-OCT) suffers from a limited imaging depth due to signal roll-off, a limited focal range, and autocorrelation noise. Here, we propose a parallel full-field FD-OCT imaging method that uses a swept laser source and an area camera in combination with an off-axis reference, which is incident on the camera at a small angle. As in digital off-axis holography, this angle separates autocorrelation signals and the complex conjugated mirror image from the actual signal in Fourier space. We demonstrate that by reconstructing the signal term only, this approach enables full-range imaging, i.e., it increases the imaging depth by a factor of two, and removes autocorrelation artifacts. The previously demonstrated techniques of inverse scattering and holoscopy can then numerically extend the focal range without loss of lateral resolution or imaging sensitivity. The resulting, significantly enhanced measurement depth is demonstrated by imaging a porcine eye over its entire depth, including cornea, lens, and retina. Finally, the feasibility of in vivo measurements is demonstrated by imaging the living human retina.

  1. Fast source camera identification using matching signs between query and reference fingerprints.

    Science.gov (United States)

    Hu, Yongjian; Li, Chang-Tsun; Lai, Zhimao

    Fast camera fingerprint search is an important issue for source camera identification in real-world applications. So far there has been little work done in this area. In this paper, we propose a novel fast search algorithm. We use global information derived from the relationship between the query fingerprint/digest and the reference fingerprints/digests in the database to guide fast search. This information can provide more accurate and robust clues for the selection of candidate matching database fingerprints. Because the quality of query fingerprints may degrade or vary in realistic applications, the construction of robust search clues is significant. To speed up the search process, we adopt a lookup table that is built on the separate-chaining hash table. The proposed algorithm has been tested using query images from real-world photos. Experiments demonstrate that our algorithm can well adapt to query fingerprints with different quality. It can achieve higher detection rates with lower computational cost than the traditional brute-force search algorithm and a pioneering fast search algorithm in literature.

  2. An Analytical Method of Auxiliary Sources Solution for Plane Wave Scattering by Impedance Cylinders - A Reference Solution for the Numerical Method of Auxiliary Sources

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2004-01-01

    To facilitate the validation of the numerical Method of Auxiliary Sources an analytical Method of Auxiliary Sources solution is derived in this paper. The Analytical solution is valid for transverse magnetic, and electric, plane wave scattering by circular impedance Cylinders, and it is derived...... of the numerical Method of Auxiliary Sources for a range of scattering configurations....... with their singularities at different positions away from the origin. The transformation necessitates a truncation of the wave transformation but the inaccuracy introduced hereby is shown to be negligible. The analytical Method of Auxiliary Sources solution is employed as a reference to investigate the accuracy...

  3. An LC-MS/MS based candidate reference method for the quantification of total gentamicin in human serum and plasma using NMR characterized calibrator material.

    Science.gov (United States)

    Lucha, Stephanie; Taibon, Judith; Pongratz, Stephan; Geletneky, Christian; Huber, Erasmus; Wintterle-Roehm, Christine; Lang, Robert; Grimm, Stefanie H; Duelffer, Thomas; Tarasov, Kirill; Zander, Johannes; Vogeser, Michael; Kobold, Uwe

    2017-01-01

    Accurate measurement of gentamicin concentration in serum and plasma is required for therapeutic drug monitoring to ensure appropriate treatment of patients. In this work, we present a validated LC-MS/MS-based candidate reference measurement procedure for total gentamicin quantification to be used for standardization and harmonization of routine assays applied for therapeutic drug monitoring of this compound. Total gentamicin is the sum of the concentrations of five known congeners C1, C1a, C2, C2a and C2b. To our knowledge, there is so far no LC-MS method for quantification of total gentamicin in human serum described in literature. Sample preparation was based on sample dilution with an aqueous internal standard solution followed by protein precipitation. Stable derivatives of gentamicin-glycine congeners were prepared by chemical synthesis and used as internal standards. The primary calibration material used in this assay was characterized by NMR spectroscopy and the pattern of the gentamicin congeners was determined. The total gentamicin was reported as the sum of the congeners which were quantified individually by LC-MS/MS. The method allows the measurement of total gentamicin in human serum and plasma in the concentration range of 0.1 to 12.0μg/ml with an assay imprecision of ≤6% CV and an assay accuracy between 96% and 114%. LOD and LOQ for the total gentamicin were 0.04μg/ml and 0.13μg/ml, respectively. Comparative measurement of 128 native patient samples using this method implemented at two laboratory sites showed an excellent agreement. Validation results proved that this protocol describes a robust and reliable method which is suggested as reference measurement procedure for the standardization and harmonization of routine assays for the quantification of total gentamicin. Copyright © 2016. Published by Elsevier B.V.

  4. Geometric Calibration Using Line Fiducials for Cone-Beam CT with General, Non-Circular Source-Detector Trajectories.

    Science.gov (United States)

    Jacobson, M W; Ketcha, M; Uneri, A; Goerres, J; De Silva, T; Reaungamornrat, S; Vogt, S; Kleinszig, G; Siewerdsen, J H

    2017-03-01

    Traditional BB-based geometric calibration methods for cone-beam CT (CBCT) rely strongly on foreknowledge of the scan trajectory shape. This is a hindrance to the implementation of variable trajectory CBCT systems, normally requiring a dedicated calibration phantom or software algorithm for every scan orbit of interest. A more flexible method of calibration is proposed here that accommodates multiple orbit types - including strongly noncircular trajectories - with a single phantom and software routine. The proposed method uses a calibration phantom consisting of multiple line-shaped wire segments. Geometric models relating the 3D line equations of the wires to the 2D line equations of their projections are used as the basis for system geometry estimation. This method was tested using a mobile C-arm CT system and comparisons were made to standard BB-based calibrations. Simulation studies were also conducted using a sinusoid-on-sphere orbit. Calibration performance was quantified in terms of Point Spread Function (PSF) width and back projection error. Visual image quality was assessed with respect to spatial resolution in trabecular bone in an anthropomorphic head phantom. The wire-based calibration method performed equal to or better than BB-based calibrations in all evaluated metrics. For the sinusoidal scans, the method provided reliable calibration, validating its application to non-circular trajectories. Furthermore, the ability to improve image quality using non-circular orbits in conjunction with this calibration method was demonstrated. The proposed method has been shown feasible for conventional circular CBCT scans and offers a promising tool for non-circular scan orbits that can improve image quality, reduce dose, and extend field of view.

  5. Experimental determinations of correction factors as a function of vertical displacement of radioactive sources in the radionuclide calibrators of the CRCN-NE, Pernambuco, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Fragoso, Maria da Conceiao de Farias; Albuquerque, Antonio Morais de Sa; Lacerda, Isabelle Viviane Batista de; Oliveira, Mercia L. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, MG (Brazil)

    2011-07-01

    In nuclear medicine, the accurate knowledge of the activity of radio-pharmaceuticals which will be administered to the patients is an important factor to ensure the success of diagnosis or therapy. The activity measurements are performed in reentrant ionization chambers, also known as radionuclide calibrators. These equipment are sensitive to changes in radioactive sample geometry and its position within the chamber well. The purpose this work was to evaluate the behavior of radionuclide calibrators by means of vertical displacement of radioactive sources in the well and to determine experimentally the correction factors for each radionuclide, recognizing the specific positions in which the measurements must be made to ensure the highest sensitivity. The highest activity was obtained between 6 and 8 cm from the bottom of the well for both radionuclide calibrators utilized at this work. (author)

  6. Calibration of scintillation cells for radon-222 measurements

    Science.gov (United States)

    Aakko, Kyllikki; Oksanen, Eero

    The calibration, of a radon-222 measurement system is described. The detector of the system is based on ZnS(Ag) coated scintillation cell. Evacuated cells are used for grab sample measurements of radon-222 in air. Three types of radioactive sources were used to evaluate the calibration coefficient. Standard activities were generated from commercially available solid and liquid radium-226 sources, and from a self-made radon-222 source whose activity was crosschecked by gamma spectrometric measurements. Radium-226 sources are traceable to US National Institute of Standards and Technology reference standards. Sources of error on calibration are discussed. Best accuracy was obtained by gamma spectrometrically crosschecked radon source. Considerable difficulties were encountered with the traditional method of emanating a known activity of radon-222 from a standard liquid radium-226 source. Three separate solid radium-226 sources gave results with rather large deviations. The final error weighted coefficients agree well with international intercalibration results.

  7. Aigaion: A Web-based Open Source Software for Managing the Bibliographic References

    OpenAIRE

    Jose, Sanjo; Jayakanth, Francis

    2008-01-01

    Publishing research papers is an integral part of a researcher's professional life. Every research article will invariably provide large number of citations/bibliographic references of the papers that are being cited in that article. All such citations are to be rendered in the citation style specified by a publisher and they should be accurate. Researchers, over a period of time, accumulate a large number of bibliographic references that are relevant to their research and cite relevant refer...

  8. The fading of Cassiopeia A, and improved models for the absolute spectrum of primary radio calibration sources

    Science.gov (United States)

    Trotter, A. S.; Reichart, D. E.; Egger, R. E.; Stýblová, J.; Paggen, M. L.; Martin, J. R.; Dutton, D. A.; Reichart, J. E.; Kumar, N. D.; Maples, M. P.; Barlow, B. N.; Berger, T. A.; Foster, A. C.; Frank, N. R.; Ghigo, F. D.; Haislip, J. B.; Heatherly, S. A.; Kouprianov, V. V.; LaCluyzé, A. P.; Moffett, D. A.; Moore, J. P.; Stanley, J. L.; White, S.

    2017-08-01

    Based on 5 yr of observations with the 40-foot telescope at Green Bank Observatory (GBO), Reichart & Stephens found that the radio source Cassiopeia A had either faded more slowly between the mid-1970s and late 1990s than Baars et al. had found it to be fading between the late 1940s and mid-1970s, or that it had rebrightened and then resumed fading sometime between the mid-1970s and mid-1990s, in the L band (1.4 GHz). Here, we present 15 additional years of observations of Cas A and Cyg A with the 40-foot in the L band, and three and a half additional years of observations of Cas A, Cyg A, Tau A and Vir A with GBO's recently refurbished 20-m telescope in the L and X (9 GHz) bands. We also present a more sophisticated analysis of the 40-foot data, and a reanalysis of the Baars et al. data, which reveals small, but non-negligible differences. We find that overall, between the late 1950s and late 2010s, Cas A faded at an average rate of 0.670 ± 0.019 per cent yr-1 in the L band, consistent with Reichart & Stephens. However, we also find, at the 6.3σ credible level, that it did not fade at a constant rate. Rather, Cas A faded at a faster rate through at least the late 1960s, rebrightened (or at least faded at a much slower rate), and then resumed fading at a similarly fast rate by, at most, the late 1990s. Given these differences from the original Baars et al. analysis, and given the importance of their fitted spectral and temporal models for flux-density calibration in radio astronomy, we update and improve on these models for all four of these radio sources. In doing so, we additionally find that Tau A is fading at a rate of 0.102^{+0.042}_{-0.043} per cent yr-1 in the L band.

  9. Reference Librarians use Electronic Sources Six Times More than Print Sources to Answer Patrons' Questions. A review of: Bradford, Jane T., Barbara Costello, and Robert Lenholt. “Reference Service in the Digital Age: An Analysis of Sources Used to Answer Reference Questions.” The Journal of Academic Librarianship 31.3 (May 2005: 263-72.

    Directory of Open Access Journals (Sweden)

    Lorie A. Kloda

    2006-06-01

    Full Text Available Objective – To test the hypothesis that electronic sources are used by librarians more often than print sources to answer questions at the reference desk. Design – Use study. Setting – Small, private university in the United States. Subjects – Five full-time and two part‐time librarians working at the reference desk for four months (two months in the fall of 2002, and two months in the spring of 2003. Methods – The study recorded every question asked by library patrons during the two study periods, with the exception of non‐library related directional questions and hardware problems. For each question recorded, librarians, while working solo at the reference desk, paraphrased the question and recorded the source(s used to answer each question. Although questions were recorded regardless of source – in person, via email, or by telephone – the medium in which each question was asked and answered was not recorded. For the first half of the study period (fall 2002 semester, librarians kept manual records that were subsequently transcribed into a spreadsheet by a student assistant. In the second half of the study period (spring 2003 semester, the librarians entered data directly into a spreadsheet. The study’s data monitor (who was also a study participant was responsible for ensuring the integrity of the data and for assigning a category to each source. The source category ‘librarian’ was problematic in that it was unclear whether or not the actual source of the answer was the librarian or a source located by the librarian. After the first half of the study, the procedure was changed to require that a reference librarian was to label a source used to answer a question as ‘librarian’ only if the answer came from a librarian’s own knowledge, and if it did not require consultation of an outside source. Categories were generated on the fly, as the data monitor reviewed the recorded questions and sources. By the end of the

  10. English and American Theatre and Drama: A Student's Guide to Reference Sources.

    Science.gov (United States)

    Claener, Ann, Comp.

    Reference works dealing with English and American theatre and drama are listed and annotated in this paper. Part One, "Reference Works," is divided into six sections: encyclopedias and handbooks; dictionaries of terms; English and American histories; biography; indexes to characters in plays and to plays in collections; and directories of…

  11. IUVS echelle-mode observations of interplanetary hydrogen: Standard for calibration and reference for cavity variations between Earth and Mars during MAVEN cruise

    Science.gov (United States)

    Mayyasi, Majd; Clarke, John; Quémerais, Eric; Katushkina, Olga; Bhattacharyya, Dolon; Chaufray, Jean-Yves; Bertaux, Jean-Loup; McClintock, Bill; Stewart, Ian; Holsclaw, Greg; Deighan, Justin; Chaffin, Michael; Schneider, Nick; Jakosky, Bruce

    2017-02-01

    The high-resolution echelle mode of the Imaging Ultraviolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile Evolution mission has been designed to measure D and H Lyman α emissions from the Martian atmosphere to obtain key information about the physical processes by which water escapes into space. Toward this goal, the absolute calibration of the instrument is critical for determining the D and H densities, the D/H ratio, and the escape flux of water. The instrument made observations of interplanetary hydrogen (IPH) along multiple look directions and conducted several postlaunch calibration campaigns during cruise as well as during orbit around Mars. The calibration efforts monitored instrument degradation and produced a consistent calibration factor at the hydrogen Lyman α wavelength (121.567 nm). The instrument was calibrated with the diffuse emission of interplanetary hydrogen (IPH) as a standard candle using measurements and model results from the Solar Wind Anisotropies (SWAN) instrument. Validation of the calibrated instrument was made by (1) comparisons to simultaneous observations of the IPH made with the lower resolution FUV mode of the IUVS instrument that were independently calibrated by using standard stars and by (2) comparisons to same-day observations of Mars at hydrogen Lyman α made with the Hubble Space Telescope that were calculated with a radiative transfer model. Adopted FUV mode values and Hubble Space Telescope-based model results agreed with the echelle SWAN calibrated values to within 6% and 4%, respectively. The calibrated IUVS instrument can be used to interpret emissions of atmospheric species at Mars for insights into water evolution at the planet, as well as observed IPH measurements made during cruise for further insights into dynamics of the inner heliosphere.

  12. European Concerted Action on Anticoagulation. A multicentre calibration study of WHO international reference preparations for thromboplastin, rabbit (RBT/90) and human (rTF/95)

    OpenAIRE

    Poller, L.; Keown, M; Chauhan, N.; van den Besselaar, A M H P; Tripodi, A.; Shiach, C; Jespersen, J

    2005-01-01

    A 10 centre calibration was performed after six years to determine the international sensitivity index (ISI) of rTF/95 relative to RBT/90, and to assess any international normalised ratio (INR) bias compared with the original multicentre calibration. After exclusion of one outlying centre, the follow up calibration gave a mean ISI for rTF/95 of 0.99, which although a small difference, is significantly greater than the mean ISI of 0.94 obtained previously. The change in ISI for international r...

  13. 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 correspondi...

  14. Laboratory implantation for well type ionization chambers calibration; Implantacao de um laboratorio para calibracao de camaras de ionizacao tipo poco

    Energy Technology Data Exchange (ETDEWEB)

    Vianello, E.A.; Dias, D.J.; Almeida, C.E. de [Laboratorio de Ciencias Radiologicas- LCR- DBB (UERJ). R. Sao Francisco Xavier, 524- Pav. HLC, sala 136 terreo- CEP 20.550-013. Rio de Janeiro (Brazil)

    1998-12-31

    The Radiological Science Laboratory is implanting a service for calibration of well type chambers by IAEA training program. The kerma rate in the air (mu Gy/h) of the linear Cs-137 reference source CDCS-J4 have been determined using a well type chamber Standard Imaging HDR-1000 model, which have been calibrated at Secondary Standard Laboratory Calibration of IAEA, whereas two HDR-1000 Plus chambers were calibrated too, following the same standards. The results were compared with Wisconsin University calibration certification and has demonstrated that well type ionization chamber calibration can be used in brachytherapy for several kinds of radionuclides. (Author)

  15. 77 FR 22067 - Publication of Inflation Adjustment Factor, Nonconventional Source Fuel Credit, and Reference...

    Science.gov (United States)

    2012-04-12

    ... Internal Revenue Service Publication of Inflation Adjustment Factor, Nonconventional Source Fuel Credit...: Notice. SUMMARY: Publication of the inflation adjustment factor, nonconventional source fuel credit, and.... section 45K). The inflation adjustment factor is used to determine the credit allowable under section 45K...

  16. Real-time dynamic calibration of a tunable frequency laser source using a Fabry-Pérot interferometer

    Science.gov (United States)

    Mandula, Gábor; Kis, Zsolt; Lengyel, Krisztián

    2015-12-01

    We report on a method for real-time dynamic calibration of a tunable external cavity diode laser by using a partially mode-matched plano-concave Fabry-Pérot interferometer in reflection geometry. Wide range laser frequency scanning is carried out by piezo-driven tilting of a diffractive grating playing the role of a frequency selective mirror in the laser cavity. The grating tilting system has a considerable mechanical inertness, so static laser frequency calibration leads to false results. The proposed real-time dynamic calibration based on the identification of primary- and Gouy-effect type secondary interference peaks with known frequency and temporal history can be used for a wide scanning range (from 0.2 GHz to more than 1 GHz). A concave spherical mirror with a radius of R = 100 cm and a plain 1% transmitting mirror was used as a Fabry-Pérot interferometer with various resonator lengths to investigate and demonstrate real-time calibration procedures for two kinds of laser frequency scanning functions.

  17. Real-time dynamic calibration of a tunable frequency laser source using a Fabry-Pérot interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Mandula, Gábor, E-mail: mandula.gabor@wigner.mta.hu; Kis, Zsolt; Lengyel, Krisztián [Wigner Research Centre for Physics of the Hungarian Academy of Sciences, Konkoly-Thege Miklós út 29-33, H-1121 Budapest (Hungary)

    2015-12-15

    We report on a method for real-time dynamic calibration of a tunable external cavity diode laser by using a partially mode-matched plano-concave Fabry-Pérot interferometer in reflection geometry. Wide range laser frequency scanning is carried out by piezo-driven tilting of a diffractive grating playing the role of a frequency selective mirror in the laser cavity. The grating tilting system has a considerable mechanical inertness, so static laser frequency calibration leads to false results. The proposed real-time dynamic calibration based on the identification of primary- and Gouy-effect type secondary interference peaks with known frequency and temporal history can be used for a wide scanning range (from 0.2 GHz to more than 1 GHz). A concave spherical mirror with a radius of R = 100 cm and a plain 1% transmitting mirror was used as a Fabry-Pérot interferometer with various resonator lengths to investigate and demonstrate real-time calibration procedures for two kinds of laser frequency scanning functions.

  18. Dark Energy Survey Year 1 Results: Cross-Correlation Redshifts in the DES -- Calibration of the Weak Lensing Source Redshift Distributions

    Energy Technology Data Exchange (ETDEWEB)

    Davis, C.; et al.

    2017-10-06

    We present the calibration of the Dark Energy Survey Year 1 (DES Y1) weak lensing source galaxy redshift distributions from clustering measurements. By cross-correlating the positions of source galaxies with luminous red galaxies selected by the redMaGiC algorithm we measure the redshift distributions of the source galaxies as placed into different tomographic bins. These measurements constrain any such shifts to an accuracy of $\\sim0.02$ and can be computed even when the clustering measurements do not span the full redshift range. The highest-redshift source bin is not constrained by the clustering measurements because of the minimal redshift overlap with the redMaGiC galaxies. We compare our constraints with those obtained from $\\texttt{COSMOS}$ 30-band photometry and find that our two very different methods produce consistent constraints.

  19. 16 CFR 1209.8 - Procedure for calibration of radiation instrumentation.

    Science.gov (United States)

    2010-01-01

    ... radiation pyrometer. Repeat for each temperature. (b) Total heat flux meter. The total flux meter shall be... meter. This latter calibration shall make use of the radiant panel tester as the heat source... maintain a dedicated calibrated reference flux meter against which one or more working flux meters can be...

  20. Utilization of PowerPoint Presentation Software in Library Instruction of Subject Specific Reference Sources.

    Science.gov (United States)

    Bushong, Sara

    This paper reports on a study conducted to determine if PowerPoint presentation is the most effective medium to explain two reference books: "The Storyteller's Sourcebook" and "A Guide to Folktales in the English Language." A secondary purpose was to see if the students who saw the PowerPoint presentation received higher…

  1. Handbook of Reference Sources and Services for Small and Medium-sized Libraries. Second Edition.

    Science.gov (United States)

    Nichols, Margaret Irby

    The primary objective of this guide is to help librarians select adult services reference tools which cover many different topics, with special emphasis on recent social and technological changes. Arrangement is topical, with particular attention given to the following topics: AIDS, abortion, the environment, economic problems, the crisis in…

  2. Motion Pictures: An Update Survey of Reference Sources, 1982-1988.

    Science.gov (United States)

    Block, Eleanor S.

    1989-01-01

    Surveys motion picture reference materials published since 1982. Materials are presented in the following categories: encyclopedic works about films, filmmakers and the industry; film criticism; people on the screen and behind it; horror, science fiction and Westerns; literature on film; catalogs and filmographies; and special collections. (70…

  3. Study on spectral calibration of an ultraviolet Fourier transform imaging spectrometer with high precision

    Science.gov (United States)

    Yang, Wenming; Liao, Ningfang; Cheng, Haobo; Li, Yasheng; Bai, Xueqiong; Deng, Chengyang

    2018-01-01

    In this paper, we reported the laboratory spectral calibration of an ultraviolet (UV) Fourier transform imaging spectrometer (FTIS). A short overview of the designed UV-FTIS, which feature with a Cassegrain objective, an Offner relay optics system and a spatial-and-temporal modulation Michelson structure, is given. The experimental setup of spectral calibration is described, including details of the light source and integrating sphere. A high pressure mercury lamp was used to acquire reference spectrum. We calculated the all optical path difference (OPD) to achieve spectral response of every wavelength sample and divided the position of reference peak to subpixel to increase the precision of spectral calibration. The spectrum of spectral calibration show two weakly responded peaks, which was validated by reference spectrum of fiber optic spectrometer. The deviation of wavelength calibration is low to establish a best spectrometer resolution. The results of spectral calibration can meet the requirements of the UV-FTIS application.

  4. TECHNIQUE OF ESTIMATION OF ERROR IN THE REFERENCE VALUE OF THE DOSE DURING THE LINEAR ACCELERATOR RADIATION OUTPUT CALIBRATION PROCEDURE. Part 2. Dependence on the characteristics of collimator, optical sourse-distance indicator, treatment field, lasers and treatment couch

    Directory of Open Access Journals (Sweden)

    Y. V. Tsitovich

    2016-01-01

    Full Text Available To ensure the safety of radiation oncology patients needed to provide consistent functional characteristics of the medical linear accelerators, which affect the accuracy of dose delivery. To this end, their quality control procedures, which include the calibration of radiation output of the linac, the error in determining the dose reference value during which must not exceed 2 %, is provided. The aim is to develop a methodology for determining the error (difference between a measured value of quantity and its true value in determining this value, depending on the characteristics of the collimator, the source to surface distance pointer, lasers, radiation field and treatment table. To achieve the objectives have been carried out dosimetric measurements of Trilogy S/N 3567 linac dose distributions, on the basis of which dose errors depending on the accuracy setting the zero position of the collimator, the deviation of the collimator rotation isocenter, the sourcesurface distance pointer accuracy, field size accuracy, the accuracy of lasers and treatment table positioning were obtained. It was found that the greatest impact on the value of the error has the error in the optical SSD indication and the error in the lasers position in the plane perpendicular to the plane of incidence of the radiation beam (up to 3.64 % for the energy of 6 MV. Dose errors caused by error in the field size were different for two photon energies, and reached 2.54 % for 6 MeV and 1.33% for 18 MeV. Errors caused by the rest of the characteristic do not exceed 1 %. Thus, it is possible to express the results of periodic quality control of these devices integrated in linac in terms of dose and use them to conduct a comprehensive assessment of the possibility of clinical use of a linear accelerator for oncology patients irradiation on the basis of the calibration of radiation output in case of development of techniques that allow to analyze the influence dosimetric

  5. Lidar to lidar calibration

    DEFF Research Database (Denmark)

    Georgieva Yankova, Ginka; Courtney, Michael

    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....

  6. ESTIMATION OF NEUTRON SCATTER CORRECTION FOR CALIBRATION OF PERSONNEL DOSIMETER AND DOSERATEMETER AGAINST 241Am-Be SOURCE-MONTE CARLO SIMULATION AND MEASUREMENTS.

    Science.gov (United States)

    Dawn, Sandipan; Bakshi, A K; Sathian, Deepa; Selvam, T Palani

    2017-06-15

    Neutron scatter contributions as a function of distance along the transverse axis of 241Am-Be source were estimated by three different methods such as shadow cone, semi-empirical and Monte Carlo. The Monte Carlo-based FLUKA code was used to simulate the existing room used for the calibration of CR-39 detector as well as LB6411 doseratemeter for selected distances from 241Am-Be source. The modified 241Am-Be spectra at different irradiation geometries such as at different source detector distances, behind the shadow cone, at the surface of the water phantom were also evaluated using Monte Carlo calculations. Neutron scatter contributions, estimated using three different methods compare reasonably well. It is proposed to use the scattering correction factors estimated through Monte Carlo simulation and other methods for the calibration of CR-39 detector and doseratemeter at 0.75 and 1 m distance from the source. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Calibração regional e local da equação de Hargreaves para estimativa da evapotranspiração de referência Regional and local calibration of Hargreaves equation for estimating reference evapotranspiration

    Directory of Open Access Journals (Sweden)

    Diego Simões Fernandes

    2012-06-01

    Full Text Available A equação de Penman-Monteith FAO-56 (EToPM tem sido recomendada pela FAO, Organização para a Alimentação e Agricultura das Nações Unidas (ONU, como padrão para estimar a evapotranspiração de referência (ETo. Essa equação requer muitas variáveis que não estão disponíveis na maioria das estações meteorológicas no Brasil central. Por outro lado, a equação de Hargreaves é considerada simples e demanda somente dados de temperatura máxima e mínima para estimar a ETo. Entretanto, essa equação requer um ajuste local. Esse estudo analisa a possibilidade de utilizar a equação de Hargreaves ajustada para estimar a ETo no estado de Goiás. Para isso, os parâmetros empíricos, HC (coeficiente empírico de Hargreaves e HE (expoente empírico de Hargreaves, da equação de Hargreaves foram ajustados considerando dois processos, ajuste local (HGR - Hargreaves ajuste local e ajuste regional (HGL - Hargreaves ajuste regional. Para o HGL, os parâmetros empíricos foram ajustados para cada estação meteorológica. Já, para o HGR, os parâmetros empíricos foram ajustados considerando conjuntamente os dados de todas as estações meteorológicas. A equação de Hargreaves ajustada para ambos os processos, local e regional, apresentou valores de ERQM de 17,95 e 21,93%, respectivamente, considerando o conjunto total de dados climáticos. A equação de Hargreaves ajustada localmente ou regionalmente é uma opção para estimar os valores diários de ETo no Estado de Goiás em locais em que a disponibilidade de dados climáticos é limitada.The FAO-56 Penman-Monteith equation (EToPM has been recommended by the Food and Agriculture Organization (FAO of the United Nations as the standard equation for estimating reference evapotranspiration (ETo. The FAO-56 PM equation requires numerous weather data that are not available in most of the stations of Brazil central. On the other hand, the Hargreaves equation is a more simple equation for

  8. Bibliography of Military History. A Selected and Annotated History of Reference Sources, 3rd ed.

    Science.gov (United States)

    Aimone, Alan C., Comp.

    This revision of the 1975 publication of the same name has increased the scope of sources to include non-print materials, and has added several new categories: Order of Battles, Abstracts, Lineages, Statistics, and Guidebooks. The previous topic headings are grouped by document type or, in some cases, by subject, such as Customs, Decorations,…

  9. Dynamic Modeling of Networks, Microgrids, and Renewable Sources in the dq0 Reference Frame

    DEFF Research Database (Denmark)

    Baimel, Dmitry; Belikov, Juri; Guerrero, Josep M.

    2017-01-01

    With increasing the penetration of distributed and renewable sources into power grids, and with increasing the use of power electronics-based devices, the dynamic behavior of large-scale power systems is becoming increasingly complex. These recent developments have led to several models attempting...... to simplify the analysis of dynamic phenomena, among them are models based on the dq0 transformation. Many recent works present dq0-based models of various power system components, ranging from small renewable sources to complete networks. The purpose of this paper is to review and categorize these works......, with an objective to promote a straightforward modeling and the analysis of complex systems, based on dq0 quantities. This paper opens by recalling basic concepts of the dq0 transformation and dq0-based models. We then review several recent works related to dq0 modeling and analysis, considering the models...

  10. Field calibration of cup anemometers

    DEFF Research Database (Denmark)

    Schmidt Paulsen, Uwe; Mortensen, Niels Gylling; Hansen, Jens Carsten

    2007-01-01

    A field calibration method and results are described along with the experience gained with the method. The cup anemometers to be calibrated are mounted in a row on a 10-m high rig and calibrated in the free wind against a reference cup anemometer. The method has been reported [1] to improve...... the statistical bias on the data relative to calibrations carried out in a wind tunnel. The methodology is sufficiently accurate for calibration of cup anemometers used for wind resource assessments and provides a simple, reliable and cost-effective solution to cup anemometer calibration, especially suited...

  11. Moderator design studies for a new neutron reference source based on the D-T fusion reaction

    Science.gov (United States)

    Mozhayev, Andrey V.; Piper, Roman K.; Rathbone, Bruce A.; McDonald, Joseph C.

    2016-06-01

    The radioactive isotope Californium-252 (252Cf) is relied upon internationally as a neutron calibration source for ionizing radiation dosimetry because of its high specific activity. The source may be placed within a heavy-water (D2O) moderating sphere to produce a softened spectrum representative of neutron fields common to commercial nuclear power plant environments, among others. Due to termination of the U.S. Department of Energy loan/lease program in 2012, the expense of obtaining 252Cf sources has undergone a significant increase, rendering high output sources largely unattainable. On the other hand, the use of neutron generators in research and industry applications has increased dramatically in recent years. Neutron generators based on deuteriumtritium (D-T) fusion reaction provide high neutron fluence rates and, therefore, could possibly be used as a replacement for 252Cf. To be viable, the 14 MeV D-T output spectrum must be significantly moderated to approximate common workplace environments. This paper presents the results of an effort to select appropriate moderating materials and design a configuration to reshape the primary neutron field toward a spectrum approaching that from a nuclear power plant workplace. A series of Monte-Carlo (MCNP) simulations of single layer high- and low-Z materials are used to identify initial candidate moderators. Candidates are refined through a similar series of simulations involving combinations of 2-5 different materials. The simulated energy distribution using these candidate moderators are rated in comparison to a target spectrum. Other properties, such as fluence preservation and/or enhancement, prompt gamma production and other characteristics are also considered.

  12. Moderator design studies for a new neutron reference source based on the D–T fusion reaction

    Energy Technology Data Exchange (ETDEWEB)

    Mozhayev, Andrey V.; Piper, Roman K.; Rathbone, Bruce A.; McDonald, Joseph C.

    2016-06-01

    The radioactive isotope Californium-252 (252Cf) is relied upon internationally as a neutron calibration source for ionizing radiation dosimetry because of its high specific activity. The source may be placed within a heavy-water (D2O) moderating sphere to produce a softened spectrum representative of neutron fields common to commercial nuclear power plant environments, among others. Due to termination of the U.S. Department of Energy loan/lease program in 2012, the expense of obtaining 252Cf sources has undergone a significant increase, rendering high output sources largely unattainable. On the other hand, the use of neutron generators in research and industry applications has increased dramatically in recent years. Neutron generators based on deuterium-tritium (D-T) fusion reaction provide high neutron fluence rates and, therefore, could possibly be used as a replacement for 252Cf. To be viable, the 14.6 MeV D-T output spectrum must be significantly moderated to approximate common workplace environments. This paper presents the results of an effort to select appropriate moderating materials and design a configuration to reshape the primary neutron field toward a spectrum approaching that from a nuclear power plant workplace. A series of Monte-Carlo (MCNP) simulations of single layer high- and low-Z materials are used to identify initial candidate moderators. Candidates are refined through a similar series of simulations involving combinations of 2 to 5 different materials. The simulated energy distribution using these candidate moderators are rated in comparison to a target spectrum. Other properties, such as fluence preservation and/or enhancement, prompt gamma production and other characteristics are also considered.

  13. Calibrating R-LINE model results with observational data to develop annual mobile source air pollutant fields at fine spatial resolution: Application in Atlanta

    Science.gov (United States)

    Zhai, Xinxin; Russell, Armistead G.; Sampath, Poornima; Mulholland, James A.; Kim, Byeong-Uk; Kim, Yunhee; D'Onofrio, David

    2016-12-01

    The Research LINE-source (R-LINE) dispersion model for near-surface releases is a dispersion model developed to estimate the impacts of line sources, such as automobiles, on primary air pollutant levels. In a multiyear application in Atlanta, R-LINE simulations overestimated concentrations and spatial gradients compared to measurements. In this study we present a computationally efficient procedure for calculating annual average spatial fields and develop an approach for calibrating R-LINE concentrations with observational data. Simulated hourly concentrations of PM2.5, CO and NOx from mobile sources at 250 m resolution in the 20-county Atlanta area based on average diurnal emission profiles and meteorological categories were used to estimate annual averages. Compared to mobile source PM2.5 impacts estimated by chemical mass balance with gas constraints (CMB-GC), a source apportionment model based on PM2.5 speciation measurements, R-LINE estimates of traffic-generated PM2.5 impacts were found to be higher by a factor of 1.8 on average across all sites. Compared to observations of daily 1 h maximum CO and NOx, R-LINE estimates were higher by factors of 1.3 and 4.2 on average, respectively. Annual averages estimated by R-LINE were calibrated by regression with observations from 2002 to 2011 at multiple sites for daily 1 h maximum CO and NOx and with measurement-based mobile source impacts estimated by CMB-GC for PM2.5. The calibration reduced normalized mean bias (NMB) from 29% to 0.3% for PM2.5, from 22% to -1% for CO, and from 303% to 49% for NOx. Cross-validation analysis (withholding sites one at a time) leads to NMB of 13%, 1%, and 69% for PM2.5, CO, and NOx, respectively. The observation-calibrated R-LINE annual average spatial fields were compared with pollutant fields from observation-blended, 12 km resolution Community Multi-scale Air Quality (CMAQ) model fields for CO and NOx, with Pearson correlation R2 values of 0.55 for CO and 0.54 for NOx found. The

  14. VLBA Scientific Memorandum n. 31: Astrometric calibration of mm-VLBI using "Source/Frequency Phase Referenced" observations

    OpenAIRE

    Dodson, Richard; Rioja, Maria J.

    2009-01-01

    In this document we layout a new method to achieve "bona fide" high precision Very-Long-Baseline-Interferometry (VLBI) astrometric measurements of frequency-dependent positions of celestial sources (even) in the high (mm-wavelength) frequency range, where conventional phase referencing techniques fail. Our method, dubbed "Source/Frequency Phase Referencing" (SFPR) combines fast frequency-switching (or dual-frequency observations) with the source switching of conventional phase referencing tec...

  15. CLUSTERED RADIO INTERFEROMETRIC CALIBRATION

    NARCIS (Netherlands)

    Kazemi, S.; Yatawatta, S.; Zaroubi, S.

    2011-01-01

    This paper introduces an amendment to radio interferometric calibration of sources below the noise level. The main idea is to employ the information of the stronger sources' measured signals as a plug-in criterion to solve for the weaker ones. For this purpose, we construct a number of source

  16. A compiled catalogue of reference stars around 227 ICRF extragalactic radio sources.

    Science.gov (United States)

    Ryl'kov, V. P.; Narizhnaya, N. V.; Dement'eva, A. A.; Pinigin, G. I.; Maigurova, N. V.; Martinov, M. V.

    A compiled catalogue of21440 stars with magnitudes from 10 to 17 is prepared on the basis of original observations made from the end of the 20th to the beginning of the 21th century. The catalogue con tains 227 fields of the cetes tial sphere around extragalactic radio sources in a declination zone from -17 to +89°. The field size is 40' for both right ascension and declination. The internal accuracy of positions for both coordinates is not worse than 0.1". The comparison of stellar positions with the use of the UCAC2 and CMC13 catalogues shows that the average external accuracy is about 0.05-0.15" for the majority ofchosenfields of the compiled catalogue. The positions of 10795 stars up to +50° in declination are given at epoch J2000.0, whereas the positions of other stars are given at the epoch of an observation.

  17. An image-based skeletal dosimetry model for the ICRP reference newborn-internal electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Pafundi, Deanna; Lee, Choonsik; Bolch, Wesley [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL (United States); Rajon, Didier [Department of Neurosurgery, University of Florida, Gainesville, FL (United States); Jokisch, Derek [Department of Physics and Astronomy, Francis Marion University, Florence, SC (United States)], E-mail: wbolch@ufl.edu

    2010-04-07

    In this study, a comprehensive electron dosimetry model of newborn skeletal tissues is presented. The model is constructed using the University of Florida newborn hybrid phantom of Lee et al (2007 Phys. Med. Biol. 52 3309-33), the newborn skeletal tissue model of Pafundi et al (2009 Phys. Med. Biol. 54 4497-531) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow (surrogate tissue for hematopoietic stem cells), shallow marrow (surrogate tissue for osteoprogenitor cells) and unossified cartilage (surrogate tissue for chondrocytes). Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following source tissues: active marrow, trabecular bone (surfaces and volumes), cortical bone (surfaces and volumes) and cartilage. Transport results are reported as specific absorbed fractions according to the MIRD schema and are given as skeletal-averaged values in the paper with bone-specific values reported in both tabular and graphic format as electronic annexes (supplementary data). The method utilized in this work uniquely includes (1) explicit accounting for the finite size and shape of newborn ossification centers (spongiosa regions), (2) explicit accounting for active and shallow marrow dose from electron emissions in cortical bone as well as sites of unossified cartilage, (3) proper accounting of the distribution of trabecular and cortical volumes and surfaces in the newborn skeleton when considering mineral bone sources and (4) explicit consideration of the marrow cellularity changes for active marrow self-irradiation as applicable to radionuclide therapy of diseased marrow in the newborn child.

  18. An image-based skeletal dosimetry model for the ICRP reference newborn—internal electron sources

    Science.gov (United States)

    Pafundi, Deanna; Rajon, Didier; Jokisch, Derek; Lee, Choonsik; Bolch, Wesley

    2010-04-01

    In this study, a comprehensive electron dosimetry model of newborn skeletal tissues is presented. The model is constructed using the University of Florida newborn hybrid phantom of Lee et al (2007 Phys. Med. Biol. 52 3309-33), the newborn skeletal tissue model of Pafundi et al (2009 Phys. Med. Biol. 54 4497-531) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow (surrogate tissue for hematopoietic stem cells), shallow marrow (surrogate tissue for osteoprogenitor cells) and unossified cartilage (surrogate tissue for chondrocytes). Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following source tissues: active marrow, trabecular bone (surfaces and volumes), cortical bone (surfaces and volumes) and cartilage. Transport results are reported as specific absorbed fractions according to the MIRD schema and are given as skeletal-averaged values in the paper with bone-specific values reported in both tabular and graphic format as electronic annexes (supplementary data). The method utilized in this work uniquely includes (1) explicit accounting for the finite size and shape of newborn ossification centers (spongiosa regions), (2) explicit accounting for active and shallow marrow dose from electron emissions in cortical bone as well as sites of unossified cartilage, (3) proper accounting of the distribution of trabecular and cortical volumes and surfaces in the newborn skeleton when considering mineral bone sources and (4) explicit consideration of the marrow cellularity changes for active marrow self-irradiation as applicable to radionuclide therapy of diseased marrow in the newborn child.

  19. Optomechanical reference accelerometer

    CERN Document Server

    Gerberding, Oliver; Melcher, John; Pratt, Jon; Taylor, Jacob

    2015-01-01

    We present an optomechanical accelerometer with high dynamic range, high bandwidth and read-out noise levels below 8 {\\mu}g/$\\sqrt{\\mathrm{Hz}}$. The straightforward assembly and low cost of our device make it a prime candidate for on-site reference calibrations and autonomous navigation. We present experimental data taken with a vacuum sealed, portable prototype and deduce the achieved bias stability and scale factor accuracy. Additionally, we present a comprehensive model of the device physics that we use to analyze the fundamental noise sources and accuracy limitations of such devices.

  20. Seed-Derived Second Harmonic source for in situ alignment and calibration of trace gas measurement instruments Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I effort will demonstrate the feasibility of developing a tunable, high-power, narrowband seed laser source integrated with a broadband,...

  1. 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)

  2. The calibration of read-out-streak photometry in the XMM-Newton Optical Monitor and the construction of a bright-source catalogue

    Science.gov (United States)

    Page, M. J.; Chan, N.; Breeveld, A. A.; Talavera, A.; Yershov, V.; Kennedy, T.; Kuin, N. P. M.; Hancock, B.; Smith, P. J.; Carter, M.

    2017-04-01

    The dynamic range of the XMM-Newton Optical Monitor (XMM-OM) is limited at the bright end by coincidence loss, the superposition of multiple photons in the individual frames recorded from its micro-channel-plate (MCP) intensified charge-coupled device (CCD) detector. One way to overcome this limitation is to use photons that arrive during the frame transfer of the CCD, forming vertical read-out streaks for bright sources. We calibrate these read-out streaks for photometry of bright sources observed with XMM-OM. The bright-source limit for read-out-streak photometry is set by the recharge time of the MCPs. For XMM-OM, we find that the MCP recharge time is 5.5 × 10-4 s. We determine that the effective bright limits for read-out-streak photometry with XMM-OM are approximately 1.5 mag brighter than the bright-source limits for normal aperture photometry in full-frame images. This translates into bright-source limits in Vega magnitudes of UVW2=7.1, UVM2=8.0, UVW1=9.4, U=10.5, B=11.5, V=10.2, and White=12.5 for data taken early in the mission. The limits brighten by up to 0.2 mag, depending on filter, over the course of the mission as the detector ages. The method is demonstrated by deriving UVW1 photometry for the symbiotic nova RR Telescopii, and the new photometry is used to constrain the e-folding time of its decaying ultraviolet (UV) emission. Using the read-out-streak method, we obtain photometry for 50 per cent of the missing UV source measurements in version 2.1 of the XMM-Newton Serendipitous UV Source Survey catalogue.

  3. An image-based skeletal dosimetry model for the ICRP reference adult female—internal electron sources

    Science.gov (United States)

    O'Reilly, Shannon E.; DeWeese, Lindsay S.; Maynard, Matthew R.; Rajon, Didier A.; Wayson, Michael B.; Marshall, Emily L.; Bolch, Wesley E.

    2016-12-01

    An image-based skeletal dosimetry model for internal electron sources was created for the ICRP-defined reference adult female. Many previous skeletal dosimetry models, which are still employed in commonly used internal dosimetry software, do not properly account for electron escape from trabecular spongiosa, electron cross-fire from cortical bone, and the impact of marrow cellularity on active marrow self-irradiation. Furthermore, these existing models do not employ the current ICRP definition of a 50 µm bone endosteum (or shallow marrow). Each of these limitations was addressed in the present study. Electron transport was completed to determine specific absorbed fractions to both active and shallow marrow of the skeletal regions of the University of Florida reference adult female. The skeletal macrostructure and microstructure were modeled separately. The bone macrostructure was based on the whole-body hybrid computational phantom of the UF series of reference models, while the bone microstructure was derived from microCT images of skeletal region samples taken from a 45 years-old female cadaver. The active and shallow marrow are typically adopted as surrogate tissue regions for the hematopoietic stem cells and osteoprogenitor cells, respectively. Source tissues included active marrow, inactive marrow, trabecular bone volume, trabecular bone surfaces, cortical bone volume, and cortical bone surfaces. Marrow cellularity was varied from 10 to 100 percent for active marrow self-irradiation. All other sources were run at the defined ICRP Publication 70 cellularity for each bone site. A total of 33 discrete electron energies, ranging from 1 keV to 10 MeV, were either simulated or analytically modeled. The method of combining skeletal macrostructure and microstructure absorbed fractions assessed using MCNPX electron transport was found to yield results similar to those determined with the PIRT model applied to the UF adult male skeletal dosimetry model. Calculated

  4. An image-based skeletal dosimetry model for the ICRP reference adult female-internal electron sources.

    Science.gov (United States)

    O'Reilly, Shannon E; DeWeese, Lindsay S; Maynard, Matthew R; Rajon, Didier A; Wayson, Michael B; Marshall, Emily L; Bolch, Wesley E

    2016-12-21

    An image-based skeletal dosimetry model for internal electron sources was created for the ICRP-defined reference adult female. Many previous skeletal dosimetry models, which are still employed in commonly used internal dosimetry software, do not properly account for electron escape from trabecular spongiosa, electron cross-fire from cortical bone, and the impact of marrow cellularity on active marrow self-irradiation. Furthermore, these existing models do not employ the current ICRP definition of a 50 µm bone endosteum (or shallow marrow). Each of these limitations was addressed in the present study. Electron transport was completed to determine specific absorbed fractions to both active and shallow marrow of the skeletal regions of the University of Florida reference adult female. The skeletal macrostructure and microstructure were modeled separately. The bone macrostructure was based on the whole-body hybrid computational phantom of the UF series of reference models, while the bone microstructure was derived from microCT images of skeletal region samples taken from a 45 years-old female cadaver. The active and shallow marrow are typically adopted as surrogate tissue regions for the hematopoietic stem cells and osteoprogenitor cells, respectively. Source tissues included active marrow, inactive marrow, trabecular bone volume, trabecular bone surfaces, cortical bone volume, and cortical bone surfaces. Marrow cellularity was varied from 10 to 100 percent for active marrow self-irradiation. All other sources were run at the defined ICRP Publication 70 cellularity for each bone site. A total of 33 discrete electron energies, ranging from 1 keV to 10 MeV, were either simulated or analytically modeled. The method of combining skeletal macrostructure and microstructure absorbed fractions assessed using MCNPX electron transport was found to yield results similar to those determined with the PIRT model applied to the UF adult male skeletal dosimetry model. Calculated

  5. Development of a certified reference material for calibration of DSC and DTA below room temperature: NMIJ CRM 5401-a, Cyclohexane for Thermal Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Yoshitaka, E-mail: y-shimizu@aist.go.jp; Ohte, Yoko; Kato, Kenji

    2013-09-20

    Highlights: • We developed a new CRM for quality assurance of DSC and DTA below room temperature. • Certified values are temperatures and enthalpies of two phase transitions. • Certified values agree with literature values. • Certified values are determined by adiabatic calorimetry and traceable to the SI. • Purity of this CRM was confirmed more than 0.9999. - Abstract: For the quality assurance of performance of differential scanning calorimeters (DSC) and differential thermal analyzers (DTA) below room temperature, we have developed “NMIJ CRM 5401-a, Cyclohexane for Thermal Analysis” applicable to calibration of DSC and DTA in the low temperature. Adiabatic calorimetry was used to measure the temperatures and enthalpies of solid–solid phase transition and fusion as certified values, and to determine the purity in amount of substance fraction as information. The certified values are consistent with their corresponding literature values within expanded uncertainties and have traceability to the SI. Purity in amount of substance fraction was measured by fractional melting method based on freezing point depression method and was confirmed to be more than 0.9999. NMIJ CRM 5401-a was produced based on a quality system in compliance with ISO Guide 34: 2000. We demonstrate the usefulness of NMIJ CRM 5401-a in the calibration, quality control, and validation aspects of DSC and DTA.

  6. An open source, 3D printed preclinical MRI phantom for repeated measures of contrast agents and reference standards.

    Science.gov (United States)

    Cox, B L; Ludwig, K D; Adamson, E B; Eliceiri, K W; Fain, S B

    2018-03-01

    In medical imaging, clinicians, researchers and technicians have begun to use 3D printing to create specialized phantoms to replace commercial ones due to their customizable and iterative nature. Presented here is the design of a 3D printed open source, reusable magnetic resonance imaging (MRI) phantom, capable of flood-filling, with removable samples for measurements of contrast agent solutions and reference standards, and for use in evaluating acquisition techniques and image reconstruction performance. The phantom was designed using SolidWorks, a computer-aided design software package. The phantom consists of custom and off-the-shelf parts and incorporates an air hole and Luer Lock system to aid in flood filling, a marker for orientation of samples in the filled mode and bolt and tube holes for assembly. The cost of construction for all materials is under $90. All design files are open-source and available for download. To demonstrate utility, B 0 field mapping was performed using a series of gadolinium concentrations in both the unfilled and flood-filled mode. An excellent linear agreement (R 2 >0.998) was observed between measured relaxation rates (R 1 /R 2 ) and gadolinium concentration. The phantom provides a reliable setup to test data acquisition and reconstruction methods and verify physical alignment in alternative nuclei MRI techniques (e.g. carbon-13 and fluorine-19 MRI). A cost-effective, open-source MRI phantom design for repeated quantitative measurement of contrast agents and reference standards in preclinical research is presented. Specifically, the work is an example of how the emerging technology of 3D printing improves flexibility and access for custom phantom design.

  7. Tetraphasic polar organic chemical integrative sampler for the determination of a wide polarity range organic pollutants in water. The use of performance reference compounds and in-situ calibration.

    Science.gov (United States)

    Iparraguirre, A; Prieto, A; Vallejo, A; Moeder, M; Zuloaga, O; Etxebarria, N; Paschke, A

    2017-03-01

    In the present work, a homemade polar organic chemical integrative sampler (POCIS) was studied for the determination of 16 target analytes. The suitability of the combination of triphasic mixture (used in so called pesticides-POCIS) and octadecyl-functionalized silica gel (C18) as sorbent for POCIS was evaluated for the determination of alkylphenols (APs), several hormones, bisphenol-A (BPA), synthetic musk fragrances and herbicides such as trifluralin (Tri) and alachlor (Ala). With this purpose, POCIS laboratory calibration study, using a continuous-flow calibration system, was carried out in order to determine the uptake behavior and sampling rate (Rs) values for each target analyte. While the most hydrophobic compounds, (synthetic musk fragrances, some APs and Tri), showed poor linearity and low accumulation, a linear accumulation was observed for compounds whose logarithmic octanol-water partition coefficient (log Kow) ranged from 5.3 (4-tert-octylphenol, 4t-OP) to 3.1 (cis-androsterone, ADT). The Rs values obtained ranged from 0.190Lday-1 (4t-OP) to 0.042Lday-1 (BPA and equilin, EQ). The addition of C18 to the commonly used triphasic mixture increased the applicability of the POCIS sampler to compounds slightly more non-polar, such as 4t-OP. As far as we know, this is the first time that a combination of tetraphasic sorbent composed by the commercially available triphasic sorbent (Isolute ENV+polystyrene divinylbenzene and Ambersorb 1500 carbon dispersed on S-X3 Biobeads) and C18 was evaluated for passive sampling of the target analytes. The developed POCIS samplers were applied in field experiments from Halle (Germany) wastewater treatment plant (WWTP) effluent. Concerning the calculation of Rs values, the time weighted average (TWA) water concentration CWTWA values were determined considering three different approaches: (i) Rs from laboratory calibration (ii) Rs from laboratory calibration corrected with the use of performance reference compounds (PRCs) and

  8. Reciprocity calibration of impulse responses of acoustic emission transducers.

    Science.gov (United States)

    Hatano, H; Chaya, T; Watanabe, S; Jinbo, K

    1998-01-01

    By means of reciprocity calibration in Rayleigh-wave and longitudinal-wave sound fields, frequency characteristics of amplitude and phase of absolute sensitivity of acoustic emission transducers were measured on the basis of the newly derived complex reciprocity parameters, and the impulse responses were obtained through inverse Fourier transform. Calibration results were confirmed with supplemental experiments in which the fracturing of a pencil lead was utilized for the source of elastic waves. Impulse responses of acoustic emission transducers to both the Rayleigh-wave and longitudinal-wave displacement velocities were determined by means of purely electrical measurements without the use of mechanical sound sources or reference transducers.

  9. Ultrasonic calibration and certification of V1 and V2 type reference standard blocks for use in Non-Destructive Testing

    OpenAIRE

    Maggi, Luís Eduardo; Silva, Cristiane Evelise Ribeiro da; Alvarenga, André Victor; Costa-Félix, Rodrigo Pereira Barretto da

    2011-01-01

    Ultrasonic Non-Destructive Testing (US-NDT) has many industrial applications,such as flaws detection, welding integrity evaluation and solid material thickness measurement.To evaluate the instrumentation conditions, before a measurement begins, a “calibration” should be carried out with the aid of a reference standard block (RSB). Types V1 (ISO 2400) and V2 (ISO 7963) are the most widely used in US-NDT. Due their characteristics, V1 and V2 RSB can be classified as Reference Material, so that ...

  10. Frequency analysis of a step dynamic pressure calibrator

    Science.gov (United States)

    Choi, In-Mook; Yang, Inseok; Yang, Tae-Heon

    2012-09-01

    A dynamic high pressure standard is becoming more essential in the fields of mobile engines, space science, and especially the area of defense such as long-range missile development. However, a complication arises when a dynamic high pressure sensor is compared with a reference dynamic pressure gauge calibrated in static mode. Also, it is difficult to determine a reference dynamic pressure signal from the calibrator because a dynamic high pressure calibrator generates unnecessary oscillations in a positive-going pressure step method. A dynamic high pressure calibrator, using a quick-opening ball valve, generates a fast step pressure change within 1 ms; however, the calibrator also generates a big impulse force that can lead to a short life-time of the system and to oscillating characteristics in response to the dynamic sensor to be calibrated. In this paper, unnecessary additional resonant frequencies besides those of the step function are characterized using frequency analysis. Accordingly, the main sources of resonance are described. In order to remove unnecessary frequencies, the post processing results, obtained by a filter, are given; also, a method for the modification of the dynamic calibration system is proposed.

  11. Reference masses for precision mass spectrometry design and implementation of a Pierce geometry to the cluster Ion source at ISOLTRAP

    CERN Document Server

    Lommen, Jonathan

    At the mass spectrometer ISOLTRAP carbon clusters ($^{12}$Cn, 1$\\leqslant$n$\\leqslant$25) are provided as reference masses, which are of particular importance in higher mass ranges (m $\\geqslant$ 200u). In this mass range the measurlment uncertainty is increasingly dominated by the difference of the reference mass and the mass of the ion of interest. Using carbon clusters instead of the common $^{133}$Cs ions, this difference decreases. The carbon clusters are produced in a laser ion source which has been improved in the frame of this thesis. The fluctuations of the count rate have been investigated as a function of the laser energy. Furthermore, the energy density at the target has been increased by implementation of a telescope into the laser beam line, which leads to a more narrow energy distribution of the ions. Through the exact adjustment of timing and length of a pulsed cavity an energy range with constant count rate could be selected. In order to provide ideal starting conditions during and after the ...

  12. 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...

  13. 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...... uncertainty was verified from independent measurements of the same sample by demonstrating statistical control of analytical results and the absence of bias. The proposed method takes into account uncertainties of the measurement, as well as of the amount of calibrant. It is applicable to all types...

  14. The Impact of Indoor and Outdoor Radiometer Calibration on Solar Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Habte, Aron; Sengupta, Manajit; Andreas, Afshin; Reda, Ibrahim; Robinson, Justin

    2016-06-02

    This study addresses the effect of calibration methodologies on calibration responsivities and the resulting impact on radiometric measurements. The calibration responsivities used in this study are provided by NREL's broadband outdoor radiometer calibration (BORCAL) and a few prominent manufacturers. The BORCAL method provides outdoor calibration responsivity of pyranometers and pyrheliometers at a 45 degree solar zenith angle and responsivity as a function of solar zenith angle determined by clear-sky comparisons to reference irradiance. The BORCAL method also employs a thermal offset correction to the calibration responsivity of single-black thermopile detectors used in pyranometers. Indoor calibrations of radiometers by their manufacturers are performed using a stable artificial light source in a side-by-side comparison of the test radiometer under calibration to a reference radiometer of the same type. These different methods of calibration demonstrated 1percent to 2 percent differences in solar irradiance measurement. Analyzing these values will ultimately enable a reduction in radiometric measurement uncertainties and assist in developing consensus on a standard for calibration.

  15. GPI Calibrations

    Science.gov (United States)

    Rantakyrö, Fredrik T.

    2017-09-01

    "The Gemini Planet Imager requires a large set of Calibrations. These can be split into two major sets, one set associated with each observation and one set related to biweekly calibrations. The observation set is to optimize the correction of miscroshifts in the IFU spectra and the latter set is for correction of detector and instrument cosmetics."

  16. Evaluation of quenching correction characteristics according to the standard source for calibration when analyzing the tritium using ultra-low-level liquid scintillation counter

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Sung Jin; Kim, Hyo Jin; Kim, Hyun; Jeong, Dong Hyeok; Kang, Yeong Rok [Research Center, Dongnam Institute of Radiological and Medical Sciences, Busan (Korea, Republic of)

    2016-12-15

    The quenching is in general corrected during the process of calibrating equipment before analyzing the environmental sample. More specifically, the samples are counted for the number of prepared samples according to the mixing ratio of source, quencher and scintillator and then the quenching correction curve is created based on the results of counting. This study intends to evaluate the differences in the quenching correction curve using the standard sources for quenching with different vial properties and then, based on the results, evaluate the effect of the concentration of tritium among environmental samples. As introduced earlier, to correct the quenching using LSC, a series of samples with different degree of quenching but with consistent activity concentration are counted in sequence and the quenching correction curve is created using software. These results indicate that if the quenching is corrected under the same conditions (scintillation cocktail, vial, etc.) as the environmental samples to be counted and analyzed, it will minimize uncertainties, thereby enabling it to obtain more accurate results.

  17. CERN radiation protection (RP) calibration facilities

    Energy Technology Data Exchange (ETDEWEB)

    Pozzi, Fabio

    2016-04-14

    , the facility was commissioned by measuring the calibration quantities of interest, e.g. H*(10), as a function of the source-to-detector distance. In the case of neutron measurements, a comparison with the Monte Carlo results was carried out; in fact, the neutron scattering can be an important issue and the Monte Carlo method can contribute to its estimation and optimization. Neutron calibrations often need to be performed at neutron energies or spectra very much different from those generated by radioactive sources employed in standard calibration laboratories. Unfortunately, fields with a broad neutron spectrum extending to a few GeVs are very rare and the scientific community is calling for worldwide sharing of the existing facilities. The CERN RP group has been managing the CERN-EU high-energy Reference Field (CERF) facility for 20 years, which is a unique calibration field in its kind. CERF is a workplace field that reproduces the neutron spectrum encountered in the vicinity of high-energy accelerators and at commercial flight altitudes. Within the context of providing a well-characterized workplace field to the scientific community, Monte Carlo simulations were performed with the present development version of the FLUKA code. The simulations were compared with experimental measurements showing promising results for the future ISO accreditation of the facility as workplace reference facility. Even though the accreditation process is fairly long, the work achieved so far is setting the bases to start this process in the right way.

  18. Field calibration of cup anemometers

    DEFF Research Database (Denmark)

    Kristensen, L.; Jensen, G.; Hansen, A.

    2001-01-01

    An outdoor calibration facility for cup anemometers, where the signals from 10 anemometers of which at least one is a reference can be can be recorded simultaneously, has been established. The results are discussed with special emphasis on the statisticalsignificance of the calibration expressions...

  19. Evaluation of stormwater micropollutant source control and end-of-pipe control strategies using an uncertainty-calibrated integrated dynamic simulation model.

    Science.gov (United States)

    Vezzaro, L; Sharma, A K; Ledin, A; Mikkelsen, P S

    2015-03-15

    The estimation of micropollutant (MP) fluxes in stormwater systems is a fundamental prerequisite when preparing strategies to reduce stormwater MP discharges to natural waters. Dynamic integrated models can be important tools in this step, as they can be used to integrate the limited data provided by monitoring campaigns and to evaluate the performance of different strategies based on model simulation results. This study presents an example where six different control strategies, including both source-control and end-of-pipe treatment, were compared. The comparison focused on fluxes of heavy metals (copper, zinc) and organic compounds (fluoranthene). MP fluxes were estimated by using an integrated dynamic model, in combination with stormwater quality measurements. MP sources were identified by using GIS land usage data, runoff quality was simulated by using a conceptual accumulation/washoff model, and a stormwater retention pond was simulated by using a dynamic treatment model based on MP inherent properties. Uncertainty in the results was estimated with a pseudo-Bayesian method. Despite the great uncertainty in the MP fluxes estimated by the runoff quality model, it was possible to compare the six scenarios in terms of discharged MP fluxes, compliance with water quality criteria, and sediment accumulation. Source-control strategies obtained better results in terms of reduction of MP emissions, but all the simulated strategies failed in fulfilling the criteria based on emission limit values. The results presented in this study shows how the efficiency of MP pollution control strategies can be quantified by combining advanced modeling tools (integrated stormwater quality model, uncertainty calibration). Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. A radio optical reference frame. I - Precise radio source positions determined by Mark III VLBI - Observations from 1979 to 1988 and a tie to the FK5

    Science.gov (United States)

    Ma, C.; Shaffer, D. B.; de Vegt, C.; Johnston, K. J.; Russell, J. L.

    1990-04-01

    Observations from 600 Mark III VLBI experiments from 1979 to 1988, resulting in 237,681 acceptable pairs of group delay and phase delay rate observations, have been used to derive positions of 182 extragalactic radio sources with typical formal standard errors less than 1 mas. The sources are distributed fairly evenly above delta = -30 deg, and 70 sources have delta greater than 0 deg. Analysis with different troposphere models, as well as internal and external comparisons, indicates that a coordinate frame defined by this set of radio sources should be reliable at the 1 mas level. The right ascension zero point of this reference frame has been aligned with the FK5 by using the optical positions of 28 extragalactic radio sources whose positions are on the FK5 system. Because of known defects in the knowledge of astronomical constants, daily nutation offsets in longitude and obliquity were determined relative to an arbitrary reference day in the set of experiments.

  1. Change of X-ray intensity in reference spectrometric gamma sources. [Radioisotopes: /sup 54/Mn, /sup 57/Co, /sup 65/Zn, /sup 88/Y, /sup 113/Sn, /sup 137/Cs, /sup 139/Ce, /sup 203/Hg, /sup 241/Am

    Energy Technology Data Exchange (ETDEWEB)

    Vylov, Ts.; Gromov, K.Ya.; Brudanin, V.B.; Matveev, S.V.; Stepanov, Eh.K.

    1982-04-01

    The results of investigations of effects influencing on the intensity of low-enegry ..gamma..- and X-radiations of reference spectrometric ..gamma..-sources (RSGS) are presented. The investigations have been performed with the aid of Ge(Li)-spectrometer. It has been found that quantum absorption in a polyethylene protective film constitutes less than 1% A /1% at the energy over 14 keV. The effect resulting from backscattering from the polyethylene film is negligibly small, whereas the increase in thickness and atomic number of substrate leads to continuous distribution distortion in the field of the spectrum line and therefore to ambiguous choice of background parameters in the course of computer spectrum unfolding. The self absorption in the source and absorption in the air layer between the detector inlet window and the source are evaluated. The conclusion is drawn on the usability of RSGS for calibrating semiconductor spectrometers by recording efficiency, when the energy is 14 keV and above.

  2. Shortwave Radiometer Calibration Methods Comparison and Resulting Solar Irradiance Measurement Differences: A User Perspective

    Energy Technology Data Exchange (ETDEWEB)

    Habte, Aron; Sengupta, Manajit; Andreas, Afshin; Reda, Ibrahim; Robinson, Justin

    2016-11-21

    Banks financing solar energy projects require assurance that these systems will produce the energy predicted. Furthermore, utility planners and grid system operators need to understand the impact of the variable solar resource on solar energy conversion system performance. Accurate solar radiation data sets reduce the expense associated with mitigating performance risk and assist in understanding the impacts of solar resource variability. The accuracy of solar radiation measured by radiometers depends on the instrument performance specification, installation method, calibration procedure, measurement conditions, maintenance practices, location, and environmental conditions. This study addresses the effect of different calibration methods provided by radiometric calibration service providers, such as NREL and manufacturers of radiometers, on the resulting calibration responsivity. Some of these radiometers are calibrated indoors and some outdoors. To establish or understand the differences in calibration methodology, we processed and analyzed field-measured data from these radiometers. This study investigates calibration responsivities provided by NREL's broadband outdoor radiometer calibration (BORCAL) and a few prominent manufacturers. The BORCAL method provides the outdoor calibration responsivity of pyranometers and pyrheliometers at 45 degree solar zenith angle, and as a function of solar zenith angle determined by clear-sky comparisons with reference irradiance. The BORCAL method also employs a thermal offset correction to the calibration responsivity of single-black thermopile detectors used in pyranometers. Indoor calibrations of radiometers by their manufacturers are performed using a stable artificial light source in a side-by-side comparison between the test radiometer under calibration and a reference radiometer of the same type. In both methods, the reference radiometer calibrations are traceable to the World Radiometric Reference (WRR). These

  3. On chromatic and geometrical calibration

    OpenAIRE

    Folm-Hansen, Jørgen

    1999-01-01

    The main subject of the present thesis is different methods for the geometrical and chromatic calibration of cameras in various environments. For the monochromatic issues of the calibration we present the acquisition of monochrome images, the classic monochrome aberrations and the various sources of non-uniformity of the illumination of the image plane. Only the image deforming aberrations and the non-uniformity of illumination are included in the calibration models. The topics of the pinhole...

  4. Reference Materials

    Science.gov (United States)

    Merkus, Henk G.

    Reference materials for measurement of particle size and porosity may be used for calibration or qualification of instruments or for validation of operating procedures or operators. They cover a broad range of materials. On the one hand there are the certified reference materials, for which governmental institutes have certified one or more typical size or porosity values. Then, there is a large group of reference materials from commercial companies. And on the other hand there are typical products in a given line of industry, where size or porosity values come from the analysis laboratory itself or from some round-robin test in a group of industrial laboratories. Their regular application is essential for adequate quality control of particle size and porosity measurement, as required in e.g., ISO 17025 on quality management. In relation to this, some quality requirements for certification are presented.

  5. Methylobacterium genome sequences: a reference blueprint to investigate microbial metabolism of C1 compounds from natural and industrial sources.

    Science.gov (United States)

    Vuilleumier, Stéphane; Chistoserdova, Ludmila; Lee, Ming-Chun; Bringel, Françoise; Lajus, Aurélie; Zhou, Yang; Gourion, Benjamin; Barbe, Valérie; Chang, Jean; Cruveiller, Stéphane; Dossat, Carole; Gillett, Will; Gruffaz, Christelle; Haugen, Eric; Hourcade, Edith; Levy, Ruth; Mangenot, Sophie; Muller, Emilie; Nadalig, Thierry; Pagni, Marco; Penny, Christian; Peyraud, Rémi; Robinson, David G; Roche, David; Rouy, Zoé; Saenampechek, Channakhone; Salvignol, Grégory; Vallenet, David; Wu, Zaining; Marx, Christopher J; Vorholt, Julia A; Olson, Maynard V; Kaul, Rajinder; Weissenbach, Jean; Médigue, Claudine; Lidstrom, Mary E

    2009-01-01

    Methylotrophy describes the ability of organisms to grow on reduced organic compounds without carbon-carbon bonds. The genomes of two pink-pigmented facultative methylotrophic bacteria of the Alpha-proteobacterial genus Methylobacterium, the reference species Methylobacterium extorquens strain AM1 and the dichloromethane-degrading strain DM4, were compared. The 6.88 Mb genome of strain AM1 comprises a 5.51 Mb chromosome, a 1.26 Mb megaplasmid and three plasmids, while the 6.12 Mb genome of strain DM4 features a 5.94 Mb chromosome and two plasmids. The chromosomes are highly syntenic and share a large majority of genes, while plasmids are mostly strain-specific, with the exception of a 130 kb region of the strain AM1 megaplasmid which is syntenic to a chromosomal region of strain DM4. Both genomes contain large sets of insertion elements, many of them strain-specific, suggesting an important potential for genomic plasticity. Most of the genomic determinants associated with methylotrophy are nearly identical, with two exceptions that illustrate the metabolic and genomic versatility of Methylobacterium. A 126 kb dichloromethane utilization (dcm) gene cluster is essential for the ability of strain DM4 to use DCM as the sole carbon and energy source for growth and is unique to strain DM4. The methylamine utilization (mau) gene cluster is only found in strain AM1, indicating that strain DM4 employs an alternative system for growth with methylamine. The dcm and mau clusters represent two of the chromosomal genomic islands (AM1: 28; DM4: 17) that were defined. The mau cluster is flanked by mobile elements, but the dcm cluster disrupts a gene annotated as chelatase and for which we propose the name "island integration determinant" (iid). These two genome sequences provide a platform for intra- and interspecies genomic comparisons in the genus Methylobacterium, and for investigations of the adaptive mechanisms which allow bacterial lineages to acquire methylotrophic

  6. Studies on dosimetric tests applying source irradiation force of Cs-137 for using in chambers for calibration and TLD type dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Laila Lorena X. [Pontificia Univ. Catolica de Goias (PUC-GO), Goiania, GO (Brazil). Dept. de Matematica, Fisica, Quimica e Engenharia de Alimentos; Barbosa, Rugles Cesar, E-mail: rbarbosa@cnen.gov.br [Centro Regional de Ciencias Nucleares do Centro Oeste (CRCN-CO/CNEN-GO), Abadia de Goias, GO (Brazil). Laboratorio de Radioprotecao; Correa, Rosangela S., E-mail: rcorrea@cnen.gov.br [Centro Regional de Ciencias Nucleares do Centro Oeste (CRCN-CO/CNEN-GO), Abadia de Goias, GO (Brazil). Laboratorio de Imagens e Dosimetria

    2011-07-01

    The West Central region of Brazil does not have a basic infrastructure for research, development, training programs, and personnel dosimetry education. All of them applied to environmental, industrial and medical uses. Service deployment for irradiance of TLD, via {sup 137}Cs irradiator J. L. SHEPHERD model 28-8A (444 activity GBq) in CRCN-CO, it is necessary to introduce procedures for calibration of the radiator and other procedures related to dosimetry and calibration. Such procedures should be repeated periodically, as necessary to introduce techniques that make the service of the CRCN-CO a template, and that meet all standards requirements for radioprotection and operation of dosimetry and calibration. The objective of this work was to evaluate the radiation field of Cs-137, and the automatic system which systematizes the calibration procedures attached to a system control target for the radiator/calibration of monitors, and portable dosimeters. (author)

  7. Site calibration

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Georgieva Yankova, Ginka

    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...... 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 [2]. The possible measurement sector for power performance...... according to [1] is also described in [2] and no results from the site calibration have shown any necessary exclusion from this sector. All parts of the sensors and the measurement system have been installed by DTU....

  8. Verification of L-band SAR calibration

    Science.gov (United States)

    Larson, R. W.; Jackson, P. L.; Kasischke, E.

    1985-01-01

    Absolute calibration of a digital L-band SAR system to an accuracy of better than 3 dB has been verified. This was accomplished with a calibration signal generator that produces the phase history of a point target. This signal relates calibration values to various SAR data sets. Values of radar cross-section (RCS) of reference reflectors were obtained using a derived calibration relationship for the L-band channel on the ERIM/CCRS X-C-L SAR system. Calibrated RCS values were compared to known RCS values of each reference reflector for verification and to obtain an error estimate. The calibration was based on the radar response to 21 calibrated reference reflectors.

  9. Based on Narcissus of radiometric calibration technology

    Science.gov (United States)

    Jin, Libing; Tang, Shaofan; Liu, Jianfeng; Peng, Honggang

    2015-08-01

    Thermal radiation is an inherent property of all objects. Generally, it is believed that the body, which temperature is above absolute zero, can keep generating infrared radiation. Infrared remote sensing, using of satellite-borne or airborne sensors, collects infrared information to identify the surface feature and inversion of surface parameters, temperature, etc. In order to get more accurately feature information, quantitative measurement is required. Infrared radiometric calibration is one of the key technologies of quantitative infrared remote sensing. Most high-resolution thermal imaging systems are cooling. For the infrared optical system which is having a cooled detector, there are some special phenomenons. Since the temperature of the detector's photosensitive surface is generally low, which is very different from system temperature, it is a very strong cold radiation source. Narcissus refers to the case that the cooled detector can "see" its own reflecting image, which may affect the image quality of infrared system seriously. But for radiometric calibration of satellite-borne infrared camera, it can sometimes take advantage of the narcissus instead of cold cryogenic radiometric calibration. In this paper, the use of narcissus to carry out radiometric calibration is summarized, and simulation results show the feasibility.

  10. Everything in its place. Social bookmarking and reference manager tools to collect, manage and cite information sources.

    Science.gov (United States)

    Giglia, E

    2010-06-01

    Aim of this contribution was to present some free reference manager software and social bookmarking tools. They help scholars and authors in recording, managing and re-using Web pages, scientific articles and bibliographic citations. Most of them support integration within the commonly used browsers or word processors, in order to easily create or import a full bibliography or a single reference.

  11. Methylobacterium genome sequences: a reference blueprint to investigate microbial metabolism of C1 compounds from natural and industrial sources.

    Directory of Open Access Journals (Sweden)

    Stéphane Vuilleumier

    Full Text Available BACKGROUND: Methylotrophy describes the ability of organisms to grow on reduced organic compounds without carbon-carbon bonds. The genomes of two pink-pigmented facultative methylotrophic bacteria of the Alpha-proteobacterial genus Methylobacterium, the reference species Methylobacterium extorquens strain AM1 and the dichloromethane-degrading strain DM4, were compared. METHODOLOGY/PRINCIPAL FINDINGS: The 6.88 Mb genome of strain AM1 comprises a 5.51 Mb chromosome, a 1.26 Mb megaplasmid and three plasmids, while the 6.12 Mb genome of strain DM4 features a 5.94 Mb chromosome and two plasmids. The chromosomes are highly syntenic and share a large majority of genes, while plasmids are mostly strain-specific, with the exception of a 130 kb region of the strain AM1 megaplasmid which is syntenic to a chromosomal region of strain DM4. Both genomes contain large sets of insertion elements, many of them strain-specific, suggesting an important potential for genomic plasticity. Most of the genomic determinants associated with methylotrophy are nearly identical, with two exceptions that illustrate the metabolic and genomic versatility of Methylobacterium. A 126 kb dichloromethane utilization (dcm gene cluster is essential for the ability of strain DM4 to use DCM as the sole carbon and energy source for growth and is unique to strain DM4. The methylamine utilization (mau gene cluster is only found in strain AM1, indicating that strain DM4 employs an alternative system for growth with methylamine. The dcm and mau clusters represent two of the chromosomal genomic islands (AM1: 28; DM4: 17 that were defined. The mau cluster is flanked by mobile elements, but the dcm cluster disrupts a gene annotated as chelatase and for which we propose the name "island integration determinant" (iid. CONCLUSION/SIGNIFICANCE: These two genome sequences provide a platform for intra- and interspecies genomic comparisons in the genus Methylobacterium, and for investigations of the

  12. On chromatic and geometrical calibration

    DEFF Research Database (Denmark)

    Folm-Hansen, Jørgen

    1999-01-01

    The main subject of the present thesis is different methods for the geometrical and chromatic calibration of cameras in various environments. For the monochromatic issues of the calibration we present the acquisition of monochrome images, the classic monochrome aberrations and the various sources...... to design calibration targets for both geometrical and chromatic calibration are described. We present some possible systematical errors on the detection of the objects in the calibration targets, if viewed in a non orthogonal angle, if the intensities are uneven or if the image blurring is uneven. Finally...... of non-uniformity of the illumination of the image plane. Only the image deforming aberrations and the non-uniformity of illumination are included in the calibration models. The topics of the pinhole camera model and the extension to the Direct Linear Transform (DLT) are described. It is shown how...

  13. Implementation of the method air-kerma product area in KAP camera calibration with reference qualities of X-ray series at the SSDL RQR of Mexico; Implementacion del metodo producto kerma en aire-area en la calibracion de camaras KAP con calidades de referencia de rayos X de la serie RQR en el LSCD de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Cejudo, Jesus; Tovar, Victor M., E-mail: jesus.cejudo@ini.gob.mx, E-mail: victor.tovar@inin.gob.mx [lnstituto Nacional de lnvestigaciones Nucleares (DMRI/LSDC/lNlN), Ocoyoacac (Mexico). Centro Nuclear Dr. Nabor Carrillo Flores. Laboratorio Secundario de Calibracion Dosimetrica

    2013-10-01

    The X-Ray machines, at a reference laboratory for the instrument calibration in diagnostic radiology, should compliance with the ISO requirements. Sometimes there is not available as much laboratories as needed in Latin American countries. So this project shows the KAP ionization chamber implementation method using the TRS-457 radiation quality from the IAEA at the SSDL of Mexico. The KAP instruments calibration method consists in doing a substitution comparison using a standard reference with traceability to a primary laboratory and a transmission-monitoring chamber that measures the number of photons of the X-ray primary beam. A KAP chamber calibration requires a special array that consists in collocating the chamber in two different positions of its calibration process. Then, with air kerma-area product coefficient together with a corrected electrometer measure at referential conditions, the patient dosimetry magnitudes are calculated. The dosimetry necessity at hospitals always will be in function of possessing a highly reliable calibration coefficient chamber for making these measures. That dosimetry results will help in reducing the total or partial irradiation emitted to the human body of the patient. This is how stochastic risks will be lessened due to diagnostic studies. The purpose of this project is to have a synergy with calibration for making known that the SSDL of Mexico has the technical capacity to act as a link between primary standard dosimetry laboratories and the ionizing radiation equipment users who require that their KAP chamber have traceability from the primary standard to the user. (author)

  14. Is popular radio a source of exposure to alcohol references in mid to later life? A content analysis

    OpenAIRE

    Haighton, Katie; Halligan, Joel; Scott, S

    2017-01-01

    Background\\ud There is concern around alcohol consumption in mid to later life yet little understanding about what influences this behaviour. No previous research has explored the extent to which adults in mid to later life may be exposed to alcohol references in the media. This project aimed to determine the frequency of alcohol references on radio stations with a high proportion of listeners in mid to later life.\\ud Methods\\ud Content analysis of alcohol references on four popular UK music-...

  15. Is popular radio a source of exposure to alcohol references in mid to later life? A content analysis.

    Science.gov (United States)

    Haighton, C; Halligan, J; Scott, S

    2017-04-20

    There is concern around alcohol consumption in mid to later life yet little understanding about what influences this behaviour. No previous research has explored the extent to which adults in mid to later life may be exposed to alcohol references in the media. This project aimed to determine the frequency of alcohol references on radio stations with a high proportion of listeners in mid to later life. Content analysis of alcohol references on four popular UK music-based radio stations with a high proportion of listeners aged 55-64 years over three time points. Alcohol references occur frequently, but vary by time of year and type of radio station. When alcohol is mentioned its consumption is portrayed as the norm, without negative consequences. On three commercial stations, the majority of mentions came from advertising, whereas on BBC Radio 2 nearly all references were talk-based. All adverts for direct promotion of alcohol were by supermarkets. Alcohol was frequently associated with celebrations, socializing or something to consume for its own sake. Adults in the age group 55-64 may be exposed to references to alcohol that could serve to reinforce norms of consumption of alcohol and promote purchases of cheap alcohol.

  16. Introduction to Reference Sources in the Health Sciences: an interview with Jo Anne Boorkman, Jeffrey T. Huber and Fred W. Roper. Interview by Elizabeth Connor.

    Science.gov (United States)

    Boorkman, Jo Anne; Huber, Jeffrey T; Roper, Fred W

    2005-01-01

    Few works serve as solid a framework for the field of health sciences librarianship or provide as many insights and detailed knowledge as Introduction to Reference Sources in the Health Sciences. Now in its fourth edition, the book's editors and contributors represent an impressive range of experience, expertise, and subject knowledge appreciated by practicing librarians in a variety of settings and by students of health sciences librarianship. Jo Anne Boorkman, Jeffrey T. Huber, and Fred W. Roper answered a series of questions about the latest edition of this seminal work, and offered opinions about reference works, services, and librarians.

  17. Mathematical efficiency calibration in gamma spectroscopy

    CERN Document Server

    Kaminski, S; Wilhelm, C

    2003-01-01

    Mathematical efficiency calibration with the LabSOCS software was introduced for two detectors in the measurement laboratory of the Central Safety Department of Forschungszentrum Karlsruhe. In the present contribution, conventional efficiency calibration of gamma spectroscopy systems and mathematical efficiency calibration with LabSOCS are compared with respect to their performance, uncertainties, expenses, and results. It is reported about the experience gained, and the advantages and disadvantages of both methods of efficiency calibration are listed. The results allow the conclusion to be drawn that mathematical efficiency calibration is a real alternative to conventional efficiency calibration of gamma spectroscopy systems as obtained by measurements of mixed gamma ray standard sources.

  18. A compact sup 3 H(p,gamma) sup 4 He 19.8 MeV gamma-ray source for energy calibration at the Sudbury Neutrino Observatory

    CERN Document Server

    Poon, A W P; Waltham, C E; Browne, M C; Robertson, R G H; Kherani, N P; Mak, H B

    2000-01-01

    The Sudbury Neutrino Observatory (SNO) is a new 1000-t D sub 2 O Cherenkov solar neutrino detector. A high-energy gamma-ray source is needed to calibrate SNO beyond the sup 8 B solar neutrino endpoint of 15 MeV. This paper describes the design and construction of a source that generates 19.8 MeV gamma rays using the sup 3 H(p,gamma) sup 4 He reaction (''pT''), and demonstrates that the source meets all the physical, operational and lifetime requirements for calibrating SNO. An ion source was built into this unit to generate and to accelerate protons up to 30 keV, and a high-purity scandium tritide target with a scandium-tritium atomic ratio of 1 : 2.0+-0.2 was included. This pT source is the first self-contained, compact, and portable high-energy gamma-ray source (E subgamma>10 MeV). (authors)

  19. A condensed {sup 83m}Kr calibration source for the KATRIN experiment; Eine kondensierte {sup 83m}Kr-Kalibrationsquelle fuer das KATRIN-Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ostrick, Beatrix

    2009-02-09

    A calibration source of condensed {sup 83m}Kr was built and tested within the frame of this thesis. The energy of the K-32-conversion electrons is fixed due to the energy of the nuclear transition and the binding energy of the K-shell electrons and for that reason it is provided with a natural stability. Alternatively to tritium measurements in the main beamline of the KATRIN experiment and permanently and synchronously at a another MAC-E-Filter (Monitor Spectrometer) this stable electron line can be used as an indicator of the stability of the HV-measurement and spectrometer conditions. {sup 83m}Kr is a short living gas with a halflife of T{sub 1/2}=1.83 h. To allow a long term monitoring the gas was condensed onto a graphite plate (HOPG). Due to the presence of the substrate the measured line position of the conversion electrons is changed. On the one hand side the work function of the substrate enters, on the other hand side the charge distribution in the substrate recorders itself under the influence of the final state of the conversion process (mirror charge). This leads to an additional binding energy of the {sup 83m}Kr{sup +}, which is transfered to the kinetic energy of the emitted electron. Both the work function and the binding energy of the final state is modified by the presence of residual gas, which is thereby the main cause of instabilities. The aim of this doctoral thesis was to define a film preparation method which leads to a reproducible energy of the conversion electrons. Therefore three methods were tested: cleaning of the substrate with a) a resister by heating, b) by laser ablation and c) preparing a fresh preplating made of stable krypton. Without ablation an ongoing pollution of the substrate appeared which shifted the line position. With ablation 19 films were prepared over the period of one month which showed a stability of 1 ppm. Thereby together with the selection of the cleanest films whose substrate was cleaned by heating, a longterm

  20. 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.

  1. Development of a Tunable LED-Based Colorimetric Source

    OpenAIRE

    Brown, Steven W.; Santana, Carlos; Eppeldauer, George P.

    2002-01-01

    A novel, spectrally tunable light-source utilizing light emitting diodes (LEDs) for radiometric, photometric, and colorimetric applications is described. The tunable source can simulate standard sources and can be used as a transfer source to propagate photometric and colorimetric scales from calibrated reference instruments to test artifacts with minimal increase in uncertainty. In this prototype source, 40 LEDs with 10 different spectral distributions were mounted onto an integrating sphere...

  2. Calibrating Legal Judgments

    Directory of Open Access Journals (Sweden)

    Frederick Schauer

    2017-09-01

    Full Text Available Objective to study the notion and essence of legal judgments calibration the possibilities of using it in the lawenforcement activity to explore the expenses and advantages of using it. Methods dialectic approach to the cognition of social phenomena which enables to analyze them in historical development and functioning in the context of the integrity of objective and subjective factors it determined the choice of the following research methods formallegal comparative legal sociological methods of cognitive psychology and philosophy. Results In ordinary life people who assess other peoplersaquos judgments typically take into account the other judgments of those they are assessing in order to calibrate the judgment presently being assessed. The restaurant and hotel rating website TripAdvisor is exemplary because it facilitates calibration by providing access to a raterrsaquos previous ratings. Such information allows a user to see whether a particular rating comes from a rater who is enthusiastic about every place she patronizes or instead from someone who is incessantly hard to please. And even when less systematized as in assessing a letter of recommendation or college transcript calibration by recourse to the decisional history of those whose judgments are being assessed is ubiquitous. Yet despite the ubiquity and utility of such calibration the legal system seems perversely to reject it. Appellate courts do not openly adjust their standard of review based on the previous judgments of the judge whose decision they are reviewing nor do judges in reviewing legislative or administrative decisions magistrates in evaluating search warrant representations or jurors in assessing witness perception. In most legal domains calibration by reference to the prior decisions of the reviewee is invisible either because it does not exist or because reviewing bodies are unwilling to admit using what they in fact know and employ. Scientific novelty for the first

  3. Deep Impact instrument calibration

    Science.gov (United States)

    Klaasen, K.; A'Hearn, M. F.; Baca, M.; Delamere, A.; Desnoyer, M.; Farnham, T.; Groussin, O.; Hampton, D.; Ipatov, S.; Li, J.-Y.; Lisse, C.; Mastrodemos, N.; McLaughlin, S.; Sunshine, J.; Thomas, P.; Wellnitz, D.

    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 [~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 ~9 pixels. The charge coupled device (CCD) read noise is ~1 DN. Electrical cross-talk between the CCD detector quadrants is correctable to <2 DN. The IR spectrometer response nonlinearity is correctable to ~1%. Spectrometer read noise is ~2 DN. The variation in zero-exposure signal level with time and spectrometer temperature is not fully characterized; currently corrections are good to ~10 DN at best. Wavelength mapping onto the detector is known within 1 pixel; spectral lines have a FWHM of ~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 ~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.

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

    Directory of Open Access Journals (Sweden)

    Jin Li

    2016-10-01

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

  5. Digital camera self-calibration

    Science.gov (United States)

    Fraser, Clive S.

    Over the 25 years since the introduction of analytical camera self-calibration there has been a revolution in close-range photogrammetric image acquisition systems. High-resolution, large-area 'digital' CCD sensors have all but replaced film cameras. Throughout the period of this transition, self-calibration models have remained essentially unchanged. This paper reviews the application of analytical self-calibration to digital cameras. Computer vision perspectives are touched upon, the quality of self-calibration is discussed, and an overview is given of each of the four main sources of departures from collinearity in CCD cameras. Practical issues are also addressed and experimental results are used to highlight important characteristics of digital camera self-calibration.

  6. Variation in the calibrated response of LiF, Al2O3, and silicon dosimeters when used for in-phantom measurements of source photons with energies between 30 KeV AND 300 KeV.

    Science.gov (United States)

    Poudel, Sashi; Currier, Blake; Medich, David C

    2015-04-01

    The MCNP5 radiation transport code was used to quantify changes in the absorbed dose conversion factor for LiF, Al2O3, and silicon-based electronic dosimeters calibrated in-air using standard techniques and summarily used to measure absorbed dose to water when placed in a water phantom. A mono-energetic photon source was modeled at energies between 30 keV and 300 keV for a point-source placed at the center of a water phantom, a point-source placed at the surface of the phantom, and for a 10-cm radial field geometry. Dosimetric calculations were obtained for water, LiF, Al2O3, and silicon at depths of 0.2 cm and 10 cm from the source. These results were achieved using the MCNP5 *FMESH photon energy-fluence tally, which was coupled with the appropriate DE/DF card for each dosimetric material studied to convert energy-fluence into the absorbed dose. The dosimeter's absorbed dose conversion factor was calculated as a ratio of the absorbed dose to water to that of the dosimeter measured at a specified phantom depth. The dosimeter's calibration value also was obtained. Based on these results, the absorbed dose conversion factor for a LiF dosimeter was found to deviate from its calibration value by up to 9%, an Al2O3 dosimeter by 43%, and a silicon dosimeter by 61%. These data therefore can be used to obtain LiF, Al2O3, and silicon dosimeter correction factors for mono-energetic and poly-energetic sources at measurement depths up to 10 cm under the irradiation geometries investigated herein.

  7. Radiometric absolute noise-temperature measurement system features improved accuracy and calibration ease

    Science.gov (United States)

    Brown, W.; Ewen, H.; Haroules, G.

    1970-01-01

    Radiometric receiver system, which measures noise temperatures in degrees Kelvin, does not require cryogenic noise sources for routine operation. It eliminates radiometer calibration errors associated with RF attenuation measurements. Calibrated noise source is required only for laboratory adjustment and calibration.

  8. Modeling, analysis, and design of stationary reference frame droop controlled parallel three-phase voltage source inverters

    DEFF Research Database (Denmark)

    Vasquez, Juan Carlos; Guerrero, Josep M.; Savaghebi, Mehdi

    2011-01-01

    Power electronics based microgrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models...

  9. Modeling, analysis, and design of stationary reference frame droop controlled parallel three-phase voltage source inverters

    DEFF Research Database (Denmark)

    Vasquez, Juan Carlos; Guerrero, Josep M.; Savaghebi, Mehdi

    2013-01-01

    Power electronics based MicroGrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of parallel connected three-phase VSIs are derived. The proposed voltage and current inner control loops...

  10. The Use of General and Specialized Corpora as Reference Sources for Academic English Writing: A Case Study

    Science.gov (United States)

    Chang, Ji-Yeon

    2014-01-01

    Corpora have been suggested as valuable sources for teaching English for academic purposes (EAP). Since previous studies have mainly focused on corpus use in classroom settings, more research is needed to reveal how students react to using corpora on their own and what should be provided to help them become autonomous corpus users, considering…

  11. Towards a global network of gamma-ray detector calibration facilities

    Science.gov (United States)

    Tijs, Marco; Koomans, Ronald; Limburg, Han

    2016-09-01

    Gamma-ray logging tools are applied worldwide. At various locations, calibration facilities are used to calibrate these gamma-ray logging systems. Several attempts have been made to cross-correlate well known calibration pits, but this cross-correlation does not include calibration facilities in Europe or private company calibration facilities. Our aim is to set-up a framework that gives the possibility to interlink all calibration facilities worldwide by using `tools of opportunity' - tools that have been calibrated in different calibration facilities, whether this usage was on a coordinated basis or by coincidence. To compare the measurement of different tools, it is important to understand the behaviour of the tools in the different calibration pits. Borehole properties, such as diameter, fluid, casing and probe diameter strongly influence the outcome of gamma-ray borehole logging. Logs need to be properly calibrated and compensated for these borehole properties in order to obtain in-situ grades or to do cross-hole correlation. Some tool providers provide tool-specific correction curves for this purpose. Others rely on reference measurements against sources of known radionuclide concentration and geometry. In this article, we present an attempt to set-up a framework for transferring `local' calibrations to be applied `globally'. This framework includes corrections for any geometry and detector size to give absolute concentrations of radionuclides from borehole measurements. This model is used to compare measurements in the calibration pits of Grand Junction, located in the USA; Adelaide (previously known as AMDEL), located in Adelaide Australia; and Stonehenge, located at Medusa Explorations BV in the Netherlands.

  12. Effect of different precursors on generation of reference spectra for structural molecular background correction by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry: Determination of antimony in cosmetics.

    Science.gov (United States)

    Barros, Ariane Isis; Victor de Babos, Diego; Ferreira, Edilene Cristina; Gomes Neto, José Anchieta

    2016-12-01

    Different precursors were evaluated for the generation of reference spectra and correction of the background caused by SiO molecules in the determination of Sb in facial cosmetics by high-resolution continuum source graphite furnace atomic absorption spectrometry employing direct solid sample analysis. Zeolite and mica were the most effective precursors for background correction during Sb determination using the 217.581nm and 231.147nm lines. Full 2 3 factorial design and central composite design were used to optimize the atomizer temperature program. The optimum pyrolysis and atomization temperatures were 1500 and 2100°C, respectively. A Pd(NO 3 ) 2 /Mg(NO 3 ) 2 mixture was employed as the chemical modifier, and calibration was performed at 217.581nm with aqueous standards containing Sb in the range 0.5-2.25ng, resulting in a correlation coefficient of 0.9995 and a slope of 0.1548s ng -1 . The sample mass was in the range 0.15-0.25mg. The accuracy of the method was determined by analysis of Montana Soil (II) certified reference material, together with addition/recovery tests. The Sb concentration found was in agreement with the certified value, at a 95% confidence level (paired t-test). Recoveries of Sb added to the samples were in the range 82-108%. The limit of quantification was 0.9mgkg -1 and the relative standard deviation (n=3) ranged from 0.5% to 7.1%. From thirteen analyzed samples, Sb was not detected in ten samples (blush, eye shadow and compact powder); three samples (two blush and one eye shadow) presented Sb concentration in the 9.1-14.5mgkg -1 range. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Calibration techniques for fringe projectors

    Science.gov (United States)

    Peters, Joerg; Patzelt, Stefan; Horn, Frank; Goch, Gert

    2001-10-01

    Fringe Projection systems generate phase distributions of an object illuminated with a specific fringe pattern. These phase correspond to the object coordinates. It is mostly necessary to transform the dimension-less phases to a metric dimension. Until today this is realized by photogrammetric techniques, which are subdivided into three main processes. At first a reference plane is defined. Then a grid within this plane is fixed. In the third step, the height axis is calibrated by different methods, for example, by use of a single height step or another well defined base object. This article describes a new method to calibrate the measuring volume by a multi-value calibration algorithm. As a first step, the fringe projection systems detects the phase distribution of a plane, denoted as reference plane. The, the plane moves stepwise in z-direction. In each step the phase distribution is detected, while an interferometer measures the distance of the z-coordinate form the reference plane. Together with the discrete x-y-coordinates of a CCD- detection unit, a 3D measuring volume is defined. The volume calibration is performed by separate polynomials for each x- y-coordinate, which are derived from the corresponding values of the phase distributions and the interferometric height values. With this method some problems of the conventional 'single value calibration' can be solved. This contribution describes the theoretical solution of the problem and presents first experimental results.

  14. drLumi: An open-source package to manage data, calibrate, and conduct quality control of multiplex bead-based immunoassays data analysis.

    Directory of Open Access Journals (Sweden)

    Hector Sanz

    Full Text Available Multiplex bead-based immunoassays are used to measure concentrations of several analytes simultaneously. These assays include control standard curves (SC to reduce between-plate variability and normalize quantitation of analytes of biological samples. Suboptimal calibration might result in large random error and decreased number of samples with analyte concentrations within the limits of quantification. Suboptimal calibration may be a consequence of poor fitness of the functions used for the SC, the treatment of the background noise and the method used to estimate the limits of quantification. Currently assessment of fitness of curves is largely dependent on operator and that may add additional error. Moreover, there is no software to automate data managing and quality control. In this article we present a R package, drLumi, with functions for managing data, calibrating assays and performing quality control. To optimize the assay the package implements: i three dose-response functions, ii four approaches for treating background noise and iii three methods for estimating limits of quantifications. Other implemented functions are focused on the quality control of the fitted standard curve: detection of outliers, estimation of the confidence or prediction interval, and estimation of summary statistics. With demonstration purpose, we apply the software to 30 cytokines, chemokines and growth factors measured in a multiplex bead-based immunoassay in a study aiming to measure correlates of risk or protection from malaria of the RTS,S malaria vaccine nested in the Phase 3 randomized controlled trial of this vaccine.

  15. Field calibration of cup anemometers

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, L.; Jensen, G.; Hansen, A.; Kirkegaard, P.

    2001-01-01

    An outdoor calibration facility for cup anemometers, where the signals from 10 anemometers of which at least one is a reference can be recorded simultaneously, has been established. The results are discussed with special emphasis on the statistical significance of the calibration expressions. It is concluded that the method has the advantage that many anemometers can be calibrated accurately with a minimum of work and cost. The obvious disadvantage is that the calibration of a set of anemometers may take more than one month in order to have wind speeds covering a sufficiently large magnitude range in a wind direction sector where we can be sure that the instruments are exposed to identical, simultaneous wind flows. Another main conclusion is that statistical uncertainty must be carefully evaluated since the individual 10 minute wind-speed averages are not statistically independent. (au)

  16. Universal calibration facility for VIS-TIR wide-angle videospectrometric airborne sensors

    Science.gov (United States)

    Oertel, Dieter; Morozova, Svetlana P.

    1994-06-01

    The European Union and DLR are funding a new 79-channel airborne imaging spectrometer: DAIS-7915, which is built by GER Corporation. Based on the requirements for ground calibration of the DAIS-7915, a Universal Calibration Facility (UCF) for VIS-TIR wide-angel videospectrometric airborne sensors has been developed at the DLR-Institute of Optoelectronic. The spectral coverage of the UCF is 0.4 - 14.5 micrometers . The UCF consists of the spectrometric-geometric calibration part (SCP), the relative diffuse radiometric source (RDRS), the thermal absolute calibration part (TACP) and the absolute radiometric calibration part (ARCP). The SCP, RDRS, and TACP can be used for laboratory calibration as well as for hangar calibration of the sensor installed in the aircraft. The ARCP consists of an integrating sphere with 165 cm diameter and an opening of 40 X 55 cm2. The sphere is intercalibrated by means of an absolute diffuse source (ADS) and a spectro- radiometer. The ADS has been recognized and admitted for application as a reference instrument for measuring the spectral radiance in the wavelength region of 0.4 - 2.5 micrometers .

  17. Calibration of Nacelle-based Lidar instrument

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Courtney, Michael

    This report presents the result of the lidar calibration performed for a two-beam nacelle based lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference 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....

  18. Calibration of Nacelle-based Lidar instrument

    DEFF Research Database (Denmark)

    Georgieva Yankova, Ginka; Courtney, Michael

    This report presents the result of the lidar calibration performed for a four-beam nacelle based lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark.Denmark. Calibration is here understood as the establishment of a relation between the reference 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....

  19. Laboratory panel and radiometer calibration

    CSIR Research Space (South Africa)

    Deadman, AJ

    2011-07-01

    Full Text Available this is not possible, that a look-up table be created to correct 8?/hemispherical reflectance values. 6. REFERENCES [1] N.P. Fox ?QA4EO-WGCV-IVO-CLP-008: Protocol for the CEOS WGCV pilot Comparison of techniques/instruments used for vicarious calibration...

  20. Proposal of a postal system for Ir-192 sources calibration used in high dose rate brachytherapy with LiF:Mn:Ti thermoluminescent dosemeters; Proposta de um sistema postal para a calibracao de fontes de {sup 192} Ir, utilizadas em braquiterapia de alta taxa de dose, com dosimetros termoluminescentes de LiF: Mn: Ti

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, W.S.; Borges, J.C.; Almeida, C.E.V. [Instituto de Radioprotecao e Dosimetria. CNEN Caixa Postal 37750, 22780-160, Rio de Janeiro (Brazil)

    1998-12-31

    A proposal in order to improve the brachytherapy quality control and to allow postal intercomparison of Ir-192 sources used in high dose rate brachytherapy has been presented. The LiF: Mn: Ti (TLD 100) detector has been selected for such purpose. The experimental array and the TLDs irradiation and calibration techniques, at the treatment units, have been specified in the light of more recent methodology of Ir-192 calibration sources. (Author)

  1. Calibration of the SNO+ experiment

    Science.gov (United States)

    Maneira, J.; Falk, E.; Leming, E.; Peeters, S.; SNO+ Collaboration.

    2017-09-01

    The main goal of the SNO+ experiment is to perform a low-background and high-isotope-mass search for neutrinoless double-beta decay, employing 780 tonnes of liquid scintillator loaded with tellurium, in its initial phase at 0.5% by mass for a total mass of 1330 kg of 130Te. The SNO+ physics program includes also measurements of geo- and reactor neutrinos, supernova and solar neutrinos. Calibrations are an essential component of the SNO+ data-taking and analysis plan. The achievement of the physics goals requires both an extensive and regular calibration. This serves several goals: the measurement of several detector parameters, the validation of the simulation model and the constraint of systematic uncertainties on the reconstruction and particle identification algorithms. SNO+ faces stringent radiopurity requirements which, in turn, largely determine the materials selection, sealing and overall design of both the sources and deployment systems. In fact, to avoid frequent access to the inner volume of the detector, several permanent optical calibration systems have been developed and installed outside that volume. At the same time, the calibration source internal deployment system was re-designed as a fully sealed system, with more stringent material selection, but following the same working principle as the system used in SNO. This poster described the overall SNO+ calibration strategy, discussed the several new and innovative sources, both optical and radioactive, and covered the developments on source deployment systems.

  2. Development of a radon standard source

    Science.gov (United States)

    Sakamoto, Shigeyasu; Ishimori, Yuu; Maruo, Yoshihiro

    2005-06-01

    The present paper describes the development of a radon standard source for use in establishing the traceability of radon concentration measurements in air. Previously, radon generated by bubbling air through a radium salt solution was widely used for calibration of radon measurement equipment; however, the handling of a solid-phase radon source is easier. In the present study, the radioactivity of radon released in a vapor phase was determined from the difference between the radioactivity of the radium and the residual radon progenies in the source. A germanium detector, calibrated using gamma reference sources, was used for these radioactivity measurements. Under equilibrium conditions the radioactivity of the radon released from the radium source was found to be 988 Bq. The source was sealed in a stainless-steel container having a nominal capacity of 6 l to produce a radon standard source of density of 167.5 [Bq/l].

  3. Calibrating pen dosimeters with and without a phantom

    Energy Technology Data Exchange (ETDEWEB)

    Nonato, Fernanda B.C.; Cescon, Claudinei T.; Caldas, Linda V.E., E-mail: fbnonato@ipen.b, E-mail: ctcescon@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Thirty one direct reading dosimeters (pen dosimeters) were calibrated and tested in standard beams of gamma radiation, with and without the use of a phantom. The calibration was performed with a Co-60 source and tested with a Cs-137 source. The dose-response curves of the pen dosimeters and their calibration factors for a Co-60 source, with and without the use of a phantom were obtained. The results show the need to calibrate the pen dosimeters with a phantom. (author)

  4. Blind calibration of radio interferometric arrays using sparsity constraints and its implications for self-calibration

    Science.gov (United States)

    Chiarucci, Simone; Wijnholds, Stefan J.

    2018-02-01

    Blind calibration, i.e. calibration without a priori knowledge of the source model, is robust to the presence of unknown sources such as transient phenomena or (low-power) broad-band radio frequency interference that escaped detection. In this paper, we present a novel method for blind calibration of a radio interferometric array assuming that the observed field only contains a small number of discrete point sources. We show the huge computational advantage over previous blind calibration methods and we assess its statistical efficiency and robustness to noise and the quality of the initial estimate. We demonstrate the method on actual data from a Low-Frequency Array low-band antenna station showing that our blind calibration is able to recover the same gain solutions as the regular calibration approach, as expected from theory and simulations. We also discuss the implications of our findings for the robustness of regular self-calibration to poor starting models.

  5. Calibration of Ground-based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement unce...

  6. Calibration of Ground -based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement unce...

  7. sources

    Directory of Open Access Journals (Sweden)

    Shu-Yin Chiang

    2002-01-01

    Full Text Available In this paper, we study the simplified models of the ATM (Asynchronous Transfer Mode multiplexer network with Bernoulli random traffic sources. Based on the model, the performance measures are analyzed by the different output service schemes.

  8. Mexican national pyronometer network calibration

    Science.gov (United States)

    VAldes, M.; Villarreal, L.; Estevez, H.; Riveros, D.

    2013-12-01

    In order to take advantage of the solar radiation as an alternate energy source it is necessary to evaluate the spatial and temporal availability. The Mexican National Meterological Service (SMN) has a network with 136 meteorological stations, each coupled with a pyronometer for measuring the global solar radiation. Some of these stations had not been calibrated in several years. The Mexican Department of Energy (SENER) in order to count on a reliable evaluation of the solar resource funded this project to calibrate the SMN pyrometer network and validate the data. The calibration of the 136 pyronometers by the intercomparison method recommended by the World Meterological Organization (WMO) requires lengthy observations and specific environmental conditions such as clear skies and a stable atmosphere, circumstances that determine the site and season of the calibration. The Solar Radiation Section of the Instituto de Geofísica of the Universidad Nacional Autónoma de México is a Regional Center of the WMO and is certified to carry out the calibration procedures and emit certificates. We are responsible for the recalibration of the pyronometer network of the SMN. A continuous emission solar simulator with exposed areas with 30cm diameters was acquired to reduce the calibration time and not depend on atmospheric conditions. We present the results of the calibration of 10 thermopile pyronometers and one photovoltaic cell by the intercomparison method with more than 10000 observations each and those obtained with the solar simulator.

  9. Phase A: calibration concepts for HIRES

    Science.gov (United States)

    Huke, Philipp; Origlia, Livia; Riva, Marco; Charsley, Jake; McCracken, Richard; Reid, Derryck; Kowzan, Grzegorz; Maslowski, Piotr; Disseau, Karen; Schäfer, Sebastian; Broeg, Christopher; Sarajlic, Mirsad; Dolon, François; Korhonen, Heidi; Reiners, Ansgar; Boisse, Isabelle; Perruchot, Sandrine; Ottogalli, Sebastien; Pepe, Francesco; Oliva, Ernesto

    2017-06-01

    The instrumentation plan for the E-ELT foresees a High Resolution Spectrograph (HIRES). Among its main goals are the detection of atmospheres of exoplanets and the determination of fundamental physical constants. For this, high radial velocity precision and accuracy are required. HIRES will be designed for maximum intrinsic stability. Systematic errors from effects like intrapixel variations or random errors like fiber noise need to be calibrated. Based on the main requirements for the calibration of HIRES, we discuss different potential calibration sources and how they can be applied. We outline the frequency calibration concept for HIRES using these sources.

  10. Fundamentals of Reference

    Science.gov (United States)

    Mulac, Carolyn M.

    2012-01-01

    The all-in-one "Reference reference" you've been waiting for, this invaluable book offers a concise introduction to reference sources and services for a variety of readers, from library staff members who are asked to work in the reference department to managers and others who wish to familiarize themselves with this important area of…

  11. 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.

  12. An image-based skeletal dosimetry model for the ICRP reference adult male—internal electron sources

    Science.gov (United States)

    Hough, Matthew; Johnson, Perry; Rajon, Didier; Jokisch, Derek; Lee, Choonsik; Bolch, Wesley

    2011-04-01

    In this study, a comprehensive electron dosimetry model of the adult male skeletal tissues is presented. The model is constructed using the University of Florida adult male hybrid phantom of Lee et al (2010 Phys. Med. Biol. 55 339-63) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow, associated with radiogenic leukemia, and total shallow marrow, associated with radiogenic bone cancer. Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following sources: bone marrow (active and inactive), trabecular bone (surfaces and volumes), and cortical bone (surfaces and volumes). Specific absorbed fractions are computed according to the MIRD schema, and are given as skeletal-averaged values in the paper with site-specific values reported in both tabular and graphical format in an electronic annex available from http://stacks.iop.org/0031-9155/56/2309/mmedia. The distribution of cortical bone and spongiosa at the macroscopic dimensions of the phantom, as well as the distribution of trabecular bone and marrow tissues at the microscopic dimensions of the phantom, is imposed through detailed analyses of whole-body ex vivo CT images (1 mm resolution) and spongiosa-specific ex vivo microCT images (30 µm resolution), respectively, taken from a 40 year male cadaver. The method utilized in this work includes: (1) explicit accounting for changes in marrow self-dose with variations in marrow cellularity, (2) explicit accounting for electron escape from spongiosa, (3) explicit consideration of spongiosa cross-fire from cortical bone, and (4) explicit consideration of the ICRP's change in the surrogate tissue region defining the location of the osteoprogenitor cells (from a 10 µm endosteal layer covering the trabecular and cortical surfaces to a 50 µm shallow marrow layer covering trabecular and medullary cavity surfaces). Skeletal

  13. An image-based skeletal dosimetry model for the ICRP reference adult male-internal electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Hough, Matthew; Johnson, Perry; Bolch, Wesley [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL (United States); Rajon, Didier [Department of Neurosurgery, University of Florida, Gainesville, FL (United States); Jokisch, Derek [Department of Physics and Astronomy, Francis Marion University, Florence, SC (United States); Lee, Choonsik, E-mail: wbolch@ufl.edu [Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD (United States)

    2011-04-21

    In this study, a comprehensive electron dosimetry model of the adult male skeletal tissues is presented. The model is constructed using the University of Florida adult male hybrid phantom of Lee et al (2010 Phys. Med. Biol. 55 339-63) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow, associated with radiogenic leukemia, and total shallow marrow, associated with radiogenic bone cancer. Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following sources: bone marrow (active and inactive), trabecular bone (surfaces and volumes), and cortical bone (surfaces and volumes). Specific absorbed fractions are computed according to the MIRD schema, and are given as skeletal-averaged values in the paper with site-specific values reported in both tabular and graphical format in an electronic annex available from http://stacks.iop.org/0031-9155/56/2309/mmedia. The distribution of cortical bone and spongiosa at the macroscopic dimensions of the phantom, as well as the distribution of trabecular bone and marrow tissues at the microscopic dimensions of the phantom, is imposed through detailed analyses of whole-body ex vivo CT images (1 mm resolution) and spongiosa-specific ex vivo microCT images (30 {mu}m resolution), respectively, taken from a 40 year male cadaver. The method utilized in this work includes: (1) explicit accounting for changes in marrow self-dose with variations in marrow cellularity, (2) explicit accounting for electron escape from spongiosa, (3) explicit consideration of spongiosa cross-fire from cortical bone, and (4) explicit consideration of the ICRP's change in the surrogate tissue region defining the location of the osteoprogenitor cells (from a 10 {mu}m endosteal layer covering the trabecular and cortical surfaces to a 50 {mu}m shallow marrow layer covering trabecular and medullary cavity surfaces). Skeletal

  14. Sources

    OpenAIRE

    2015-01-01

    Sources Fondation Pablo Iglesias. Alcala de Henares. Sections : Archives privées de Manuel ArijaArchives extérieuresArchives FNJS de EspañaPrensa Archives Générales de l’Administration. Alcala de Henares. Sections : Opposition au franquismeSig. 653 Sig TOP 82/68.103-68.602.Índice de las cartas colectivas, Relaciones, Cartas al Ministro de Información de Marzo de 1965. c.662. Sources cinématographiques Filmothèque Nationale d’Espagne.NO.DO. N° 1157C. 08/03/1965.aguirre Javier, Blanco vertical....

  15. Long-Term Stability Assessment of Sonoran Desert for Vicarious Calibration of GOES-R

    Science.gov (United States)

    Kim, W.; Liang, S.; Cao, C.

    2012-12-01

    Vicarious calibration refers to calibration techniques that do not depend on onboard calibration devices. Although sensors and onboard calibration devices undergo rigorous validation processes before launch, performance of sensors often degrades after the launch due to exposure to the harsh space environment and the aging of devices. Such in-flight changes of devices can be identified and adjusted through vicarious calibration activities where the sensor degradation is measured in reference to exterior calibration sources such as the Sun, the Moon, and the Earth surface. Sonoran desert is one of the best calibration sites located in the North America that are available for vicarious calibration of GOES-R satellite. To accurately calibrate sensors onboard GOES-R satellite (e.g. advanced baseline imager (ABI)), the temporal stability of Sonoran desert needs to be assessed precisely. However, short-/mid-term variations in top-of-atmosphere (TOA) reflectance caused by meteorological variables such as water vapor amount and aerosol loading are often difficult to retrieve, making the use of TOA reflectance time series for the stability assessment of the site. In this paper, we address this issue of normalization of TOA reflectance time series using a time series analysis algorithm - seasonal trend decomposition procedure based on LOESS (STL) (Cleveland et al, 1990). The algorithm is basically a collection of smoothing filters which leads to decomposition of a time series into three additive components; seasonal, trend, and remainder. Since this non-linear technique is capable of extracting seasonal patterns in the presence of trend changes, the seasonal variation can be effectively identified in the time series of remote sensing data subject to various environmental changes. The experiment results performed with Landsat 5 TM data show that the decomposition results acquired for the Sonoran Desert area produce normalized series that have much less uncertainty than those

  16. Inclusion of thin target and source regions in alimentary and respiratory tract systems of mesh-type ICRP adult reference phantoms

    Science.gov (United States)

    Kim, Han Sung; Yeom, Yeon Soo; Tat Nguyen, Thang; Choi, Chansoo; Han, Min Cheol; Lee, Jai Ki; Kim, Chan Hyeong; Zankl, Maria; Petoussi-Henss, Nina; Bolch, Wesley E.; Lee, Choonsik; Qiu, Rui; Eckerman, Keith; Chung, Beom Sun

    2017-03-01

    It is not feasible to define very small or complex organs and tissues in the current voxel-type adult reference computational phantoms of the International Commission on Radiological Protection (ICRP), which limit dose coefficients for weakly penetrating radiations. To address the problem, the ICRP is converting the voxel-type reference phantoms into mesh-type phantoms. In the present study, as a part of the conversion project, the micrometer-thick target and source regions in the alimentary and respiratory tract systems as described in ICRP Publications 100 and 66 were included in the mesh-type ICRP reference adult male and female phantoms. In addition, realistic lung airway models were simulated to represent the bronchial (BB) and bronchiolar (bb) regions. The electron specific absorbed fraction (SAF) values for the alimentary and respiratory tract systems were then calculated and compared with the values calculated with the stylized models of ICRP Publications 100 and 66. The comparisons show generally good agreement for the oral cavity, oesophagus, and BB, whereas for the stomach, small intestine, large intestine, extrathoracic region, and bb, there are some differences (e.g. up to ~9 times in the large intestine). The difference is mainly due to anatomical difference in these organs between the realistic mesh-type phantoms and the simplified stylized models. The new alimentary and respiratory tract models in the mesh-type ICRP reference phantoms preserve the topology and dimensions of the voxel-type ICRP phantoms and provide more reliable SAF values than the simplified models adopted in previous ICRP Publications.

  17. Inclusion of thin target and source regions in alimentary and respiratory tract systems of mesh-type ICRP adult reference phantoms.

    Science.gov (United States)

    Kim, Han Sung; Yeom, Yeon Soo; Nguyen, Thang Tat; Choi, Chansoo; Han, Min Cheol; Lee, Jai Ki; Kim, Chan Hyeong; Zankl, Maria; Petoussi-Henss, Nina; Bolch, Wesley E; Lee, Choonsik; Qiu, Rui; Eckerman, Keith; Chung, Beom Sun

    2017-03-21

    It is not feasible to define very small or complex organs and tissues in the current voxel-type adult reference computational phantoms of the International Commission on Radiological Protection (ICRP), which limit dose coefficients for weakly penetrating radiations. To address the problem, the ICRP is converting the voxel-type reference phantoms into mesh-type phantoms. In the present study, as a part of the conversion project, the micrometer-thick target and source regions in the alimentary and respiratory tract systems as described in ICRP Publications 100 and 66 were included in the mesh-type ICRP reference adult male and female phantoms. In addition, realistic lung airway models were simulated to represent the bronchial (BB) and bronchiolar (bb) regions. The electron specific absorbed fraction (SAF) values for the alimentary and respiratory tract systems were then calculated and compared with the values calculated with the stylized models of ICRP Publications 100 and 66. The comparisons show generally good agreement for the oral cavity, oesophagus, and BB, whereas for the stomach, small intestine, large intestine, extrathoracic region, and bb, there are some differences (e.g. up to ~9 times in the large intestine). The difference is mainly due to anatomical difference in these organs between the realistic mesh-type phantoms and the simplified stylized models. The new alimentary and respiratory tract models in the mesh-type ICRP reference phantoms preserve the topology and dimensions of the voxel-type ICRP phantoms and provide more reliable SAF values than the simplified models adopted in previous ICRP Publications.

  18. Geometric calibration of ERS satellite SAR images

    DEFF Research Database (Denmark)

    Mohr, Johan Jacob; Madsen, Søren Nørvang

    2001-01-01

    Geometric calibration of the European Remote Sensing (ERS) Satellite synthetic aperture radar (SAR) slant range images is important in relation to mapping areas without ground reference points and also in relation to automated processing. The relevant SAR system parameters are discussed and calib......Geometric calibration of the European Remote Sensing (ERS) Satellite synthetic aperture radar (SAR) slant range images is important in relation to mapping areas without ground reference points and also in relation to automated processing. The relevant SAR system parameters are discussed...... on a seven-year ERS-1 and a four-year ERS-2 time series, the long term stability is found to be sufficient to allow a single calibration covering the entire mission period. A descending and an ascending orbit tandem pair of the ESA calibration site on Flevoland, suitable for calibration of ERS SAR processors...

  19. 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...

  20. Optimization of geometrical calibration in pinhole SPECT.

    Science.gov (United States)

    Bequé, Dirk; Nuyts, Johan; Suetens, Paul; Bormans, Guy

    2005-02-01

    Previously, we developed a method to determine the acquisition geometry of a pinhole camera. This information is needed for the correct reconstruction of pinhole single photon emission computed tomography images. The method uses a calibration phantom consisting of three point sources and their positions in the field of view (FOV) influence the accuracy of the geometry estimate. This paper proposes two particular configurations of point sources with specific positions and orientations in the FOV for optimal image reconstruction accuracy. For the proposed calibration setups, inaccuracies of the geometry estimate due to noise in the calibration data, only cause subresolution inaccuracies in reconstructed images. The calibration method also uses a model of the point source configuration, which is only known with limited accuracy. The study demonstrates, however, that, with the proposed calibration setups, the error in reconstructed images is comparable to the error in the phantom model.

  1. INFLUENCE OF SCATTERED NEUTRON RADIATION ON METROLOGICAL CHARACTERISTICS OF АТ140 NEUTRON CALIBRATION FACILITY

    Directory of Open Access Journals (Sweden)

    D. I. Komar

    2017-01-01

    Full Text Available Today facilities with collimated radiation field are widely used as reference in metrological support of devices for neutron radiation measurement. Neutron fields formed by radionuclide neutron sources. The aim of this research was to study characteristics of experimentally realized neutron fields geometries on АТ140 Neutron Calibration Facility using Monte Carlo method.For calibration, we put a device into neutron field with known flux density or ambient equivalent dose rate. We can form neutron beam from radionuclide fast-neutron source in different geometries. In containercollimator of АТ140 Neutron Calibration Facility we can install special inserts to gather fast-neutron geometry or thermal-neutron geometry. We need to consider neutron scattering from air and room’s walls. We can conduct measurements of neutron field characteristics in several points and get the other using Monte Carlo method.Thermal neutron collimator forms a beam from radionuclide source with a significant amount of neutrons with thermal energies. From found relationship between full neutron flux and distance to neutron source we see that inverse square law is violated. Scattered radiation contribution into total flux increases when we are moving away from neutron source and significantly influences neutron fields characteristics. While source is exposed in shadow-cone geometry neutron specter has pronounced thermal component from wall scattering.In this work, we examined main geometry types used to acquire reference neutron radiation using radionuclide sources. We developed Monte Carlo model for 238Pu-Be neutron source and АТ140 Neutron Calibration Facility’s container-collimator. We have shown the most significant neutron energy distribution factor to be scattered radiation from room’s walls. It leads to significant changes of neutron radiation specter at a distance from the source. When planning location, and installing the facility we should consider

  2. An Improved Calibration Method for Hydrazine Monitors for the United States Air Force

    Energy Technology Data Exchange (ETDEWEB)

    Korsah, K

    2003-07-07

    Kintek system output concentration is less than the calculated output of the generator alone but can be calibrated as a system by using coulometric titration of gas samples collected with impingers. (3) The calibrated Kintek system output concentration is reproducible even after having been disassembled and moved and reassembled. (4) The uncertainty of the reference gas concentration generated by the Kintek system is less than half the uncertainty of the Zellweger Analytics' (ZA) reference gas concentration and can be easily lowered to one third or less of the ZA method by using lower-uncertainty flow rate or total flow measuring instruments. (5) The largest sources of uncertainty in the current ORNL calibration system are the permeation rate of the permeation tubes and the flow rate of the impinger sampling pump used to collect gas samples for calibrating the Kintek system. Upgrading the measurement equipment, as stated in (4), can reduce both of these. (6) The coulometric titration technique can be used to periodically assess the performance of the Kintek system and determine a suitable recalibration interval. (7) The Kintek system has been used to calibrate two MDA 7100s and an Interscan 4187 in less than one workday. The system can be upgraded (e.g., by automating it) to provide more calibrations per day. (8) The humidity of both the reference gas and the environment of the Chemcassette affect the MDA 7100 hydrazine detector's readings. However, ORNL believes that the environmental effect is less significant than the effect of the reference gas humidity. (9) The ORNL calibration method based on the Kintek 491 M-B gas standard can correct for the effect of the humidity of the reference gas to produce the same calibration as that of ZA's. Zellweger Analytics calibrations are typically performed at 45%-55% relative humidity. (10) Tests using the Interscan 4187 showed that the instrument was not accurate in its lower (0-100 ppb) range. Subsequent

  3. jasonSWIR Calibration of Spectralon Reflectance Factor

    Science.gov (United States)

    Georgiev, Georgi T.; Butler, James J.; Cooksey, Cahterine; Ding, Leibo; Thome, Kurtis J.

    2011-01-01

    Satellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Factor (BRF) of laboratory-based diffusers used in their pre-flight and on-orbit radiometric calibrations. BRF measurements are required throughout the reflected-solar spectrum from the ultraviolet through the shortwave infrared. Spectralon diffusers are commonly used as a reflectance standard for bidirectional and hemispherical geometries. The Diffuser Calibration Laboratory (DCaL) at NASA's Goddard Space Flight Center is a secondary calibration facility with reflectance measurements traceable to those made by the Spectral Tri-function Automated Reference Reflectometer (STARR) facility at the National Institute of Standards and Technology (NIST). For more than two decades, the DCaL has provided numerous NASA projects with BRF data in the ultraviolet (UV), visible (VIS) and the Near infraRed (NIR) spectral regions. Presented in this paper are measurements of BRF from 1475nm to 1625nm obtained using an indium gallium arsenide detector and a tunable coherent light source. The sample was a 2 inch diameter, 99% white Spectralon target. The BRF results are discussed and compared to empirically generated data from a model based on NIST certified values of 6deg directional/hemispherical spectral reflectance factors from 900nm to 2500nm. Employing a new NIST capability for measuring bidirectional reflectance using a cooled, extended InGaAs detector, BRF calibration measurements of the same sample were also made using NIST's STARR from 1475nm to 1625nm at an incident angle of 0deg and at viewing angles of 40deg, 45deg, and 50deg. The total combined uncertainty for BRF in this ShortWave Infrared (SWIR) range is less than 1%. This measurement capability will evolve into a BRF calibration service in SWIR region in support of NASA remote sensing missions. Keywords: BRF, BRDF, Calibration, Spectralon, Reflectance, Remote Sensing.

  4. Transmittance measurement of a heliostat facility used in the preflight radiometric calibration of Earth-observing sensors

    Science.gov (United States)

    Czapla-Myers, J.; Thome, K.; Anderson, N.; McCorkel, J.; Leisso, N.; Good, W.; Collins, S.

    2009-08-01

    Ball Aerospace and Technologies Corporation in Boulder, Colorado, has developed a heliostat facility that will be used to determine the preflight radiometric calibration of Earth-observing sensors that operate in the solar-reflective regime. While automatically tracking the Sun, the heliostat directs the solar beam inside a thermal vacuum chamber, where the sensor under test resides. The main advantage to using the Sun as the illumination source for preflight radiometric calibration is because it will also be the source of illumination when the sensor is in flight. This minimizes errors in the pre- and post-launch calibration due to spectral mismatches. It also allows the instrument under test to operate at irradiance values similar to those on orbit. The Remote Sensing Group at the University of Arizona measured the transmittance of the heliostat facility using three methods, the first of which is a relative measurement made using a hyperspectral portable spectroradiometer and well-calibrated reference panel. The second method is also a relative measurement, and uses a 12-channel automated solar radiometer. The final method is an absolute measurement using a hyperspectral spectroradiometer and reference panel combination, where the spectroradiometer is calibrated on site using a solar-radiation-based calibration.

  5. Sources

    OpenAIRE

    2014-01-01

    Archives Archivo Histórico del Estado de Jalisco Fondo Gobernación, Asunto Pasaportes y Salvoconductos : G-8-877/9773-9775 G-8-878/9774, 9776, 9777 et 9781 G-8-879/9782-9788 G-8-880/9789-9798 G-8-881-882/9803 G-8-882/9804-9805 G-8-883/9806-9811 G-8-884/9813 G-8-885/9817-9820 G-8-886/9822-9825 G-8-887/9826-9830 G-8-888/9835 G-8-889-890/9837 G-8-889/9839 Sources imprimées Livres et chroniques O’Farrill Romulo, (2004) Reseña histórica estadística y comercial de México y sus estados, directorio g...

  6. Calibration services for medical applications of radiation

    Energy Technology Data Exchange (ETDEWEB)

    DeWerd, L.A.

    1993-12-31

    Calibration services for the medical community applications of radiation involve measuring radiation precisely and having traceability to the National Institute of Standards and Technology (NIST). Radiation therapy applications involve the use of ionization chambers and electrometers for external beams and well-type ionization chamber systems as well as radioactive sources for brachytherapy. Diagnostic x-ray applications involve ionization chamber systems and devices to measure other parameters of the x-ray machine, such as non-invasive kVp meters. Calibration laboratories have been established to provide radiation calibration services while maintaining traceability to NIST. New radiation applications of the medical community spur investigation to provide the future calibration needs.

  7. FY2008 Calibration Systems Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, Bret D.; Myers, Tanya L.; Broocks, Bryan T.

    2009-01-01

    The Calibrations project has been exploring alternative technologies for calibration of passive sensors in the infrared (IR) spectral region. In particular, we have investigated using quantum cascade lasers (QCLs) because these devices offer several advantages over conventional blackbodies such as reductions in size and weight while providing a spectral source in the IR with high output power. These devices can provide a rapid, multi-level radiance scheme to fit any nonlinear behavior as well as a spectral calibration that includes the fore-optics, which is currently not available for on-board calibration systems.

  8. NIST display colorimeter calibration facility

    Science.gov (United States)

    Brown, Steven W.; Ohno, Yoshihiro

    2003-07-01

    A facility has been developed at the National Institute of Standards and Technology (NIST) to provide calibration services for color-measuring instruments to address the need for improving and certifying the measurement uncertainties of this type of instrument. While NIST has active programs in photometry, flat panel display metrology, and color and appearance measurements, these are the first services offered by NIST tailored to color-measuring instruments for displays. An overview of the facility, the calibration approach, and associated uncertainties are presented. Details of a new tunable colorimetric source and the development of new transfer standard instruments are discussed.

  9. Calibration of low light/near infrared cameras with satellite remote sensing to measure incandescence and thermal signatures for source parameter estimation

    Science.gov (United States)

    Harrild, M.; Webley, P.; Dehn, J.

    2013-12-01

    Volcanic activity ranges from low level lava effusion to large explosive eruptions, easily capable of ejecting ash up to aircraft cruise altitudes. Knowledge and understanding of precursory activity and thermal signatures are vital for monitoring volcanogenic processes. For many years, satellite remote sensing has been used to determine effusion rates and expensive ground based thermal cameras can calibrate these measurements. However, this investigation explores the use of webcams to image volcanic activity in the visible to near-infrared (NIR) portion of the spectrum, by comparison of webcam pixel brightness to temperatures obtained from co-located FLIR cameras. By determining this relationship, webcam imagery can be used to approximate volcanic eruption temperatures, indicating changes in activity. A field campaign, presented here, to Stromboli, June 2013, demonstrates the use of co-located cameras to determine temperatures from pixel brightness resulting from various Type 1, 2a and 2b eruptions. This method is ideal for monitoring (particularly in remote locations) as the cameras are cheap, consume little power, are easily replaced, provide near real-time data and the images can be compared to satellite observations. A plethora of webcam imagery also exists for past eruptions, that will be analyzed and initial results are presented. Preliminary investigations were conducted in laboratory settings to determine saturation levels of each camera (wavelength dependent) and the required temporal resolution to accurately detect thermal signatures and calculate rise rates. Combined together and coupled with other observations such as seismic, infrasonic and space-borne, this data analysis will provide an increased understanding into volcanogenic processes. Two pairs of time co-incidental images showing the progression of an eruption from Stromboli's southwest crater on June 23rd 2013 at 20:52:15 and 20:52:19 UTC. a) and c) show thermal infrared images taken using a

  10. Best Reference Practices are Not Observed in Telephone Ready Reference Services. A review of: Agosto, Denise A. and Holly Anderton. “Whatever Happened to ‘Always Cite the Source?’” Reference & User Services Quarterly 47.1 (2007: 44-54.

    Directory of Open Access Journals (Sweden)

    Julie McKenna

    2008-06-01

    Full Text Available Objective – To study source citing practice in telephone reference service in large public libraries in the United States and Canada. Design – Field simulation (unobtrusive testing.Setting – Large public libraries in the United States and Canada.Subjects – Telephone reference staff of the 25 largest public libraries in the United States and Canada.Methods – The 2005 World Book Almanac was used to select the 25 largest (in terms of population served public libraries in Canada and the United States. Each system’s Web site was checked to locate the telephone number for reference service. For some systems it was necessary to call the general telephone number for the main library or the first branch listed on the Web site. Five ready reference test questions were developed from a list of questions that students in a graduate library and information science course had previously asked of public library telephone reference services. The selected questions in the order that they were asked were: 1. Can you tell me when Valentine’s Day is?2. Who is the current governor/premier (of the state/province where the library is located?3. What is the population of Montana?4. In which state is the Southern Poverty Law Center (SPLC located?5. What is the French word for “chiropractor”?The authors called each of the 25 libraries during five consecutive weeks at different times of the business day. Each week, one question was asked; once an answer was received, no clarification was requested and the call was ended. The study reports the results of 125 reference transactions. For this study, the following definitions were used to assess complete citation for each type of information resource:• For a Web site – the complete URL (title and sponsor of the site not required.• For a digital database – the database title and the title and year of the specific item (author, publisher, page number not required.• For a print resource – the title

  11. Calibration of soil heat flux sensors.

    NARCIS (Netherlands)

    Loon, van W.K.P.; Bastings, H.M.H.; Moors, E.J.

    1998-01-01

    Soil heat flux is difficult to measure accurately and soil heat flux plates are difficult to calibrate. In this research the reference heat flux was calculated from the temperature gradient and independent thermal conductivity measurements. Reference conductivities, as measured by the non-steady

  12. New numerical simulation method to calibrate the regular hexagonal NaI(Tl) detector with radioactive point sources situated non-axial

    Science.gov (United States)

    Hamzawy, Ayman; Grozdanov, Dimitar N.; Badawi, Mohamed S.; Aliyev, Fuad A.; Thabet, Abouzeid A.; Abbas, Mahmoud I.; Ruskov, Ivan N.; El-Khatib, Ahmed M.; Kopatch, Yuri N.; Gouda, Mona M.

    2016-11-01

    Scintillation crystals are usually used for detection of energetic photons at room temperature in high energy and nuclear physics research, non-destructive analysis of materials testing, safeguards, nuclear treaty verification, geological exploration, and medical imaging. Therefore, new designs and construction of radioactive beam facilities are coming on-line with these science brunches. A good number of researchers are investigating the efficiency of the γ-ray detectors to improve the models and techniques used in order to deal with the most pressing problems in physics research today. In the present work, a new integrative and uncomplicated numerical simulation method (NSM) is used to compute the full-energy (photo) peak efficiency of a regular hexagonal prism NaI(Tl) gamma-ray detector using radioactive point sources situated non-axial within its front surface boundaries. This simulation method is based on the efficiency transfer method. Most of the mathematical formulas in this work are derived analytically and solved numerically. The main core of the NSM is the calculation of the effective solid angle for radioactive point sources, which are situated non-axially at different distances from the front surface of the detector. The attenuation of the γ-rays through the detector's material and any other materials in-between the source and the detector is taken into account. A remarkable agreement between the experimental and calculated by present formalism results has been observed.

  13. Optical calibration of SNO +

    Science.gov (United States)

    Leming, Edward; SNO+ Collaboration

    2015-04-01

    Situated 2 km underground in Sudbury, Northern Ontario, the SNO + detector consists of an acrylic sphere 12 m in diameter containing 780 tons of target mass, surrounded by approximately 9,500 PMTs. For SNO, this target mass was heavy water, however the change to SNO + is defined by the change of this target mass to a novel scintillator. With the lower energy threshold, low intrinsic radioactivity levels and the best shielding against muons and cosmogenic activation of all existing neutrino experiments, SNO + will be sensitive to exciting new physics. The experiment will be studying solar, reactor, super nova and geo-neutrinos, though the main purpose of SNO + is the search for neutrinoless double-beta decay of Te-130. To meet the requirements imposed by the physics on detector performance, a detailed optical calibration is needed. Source deployment must be kept to a minimum and eliminated if possible, in order to meet the stringent radiopurity requirements. This led to the development of the Embedded LED/laser Light Injection Entity (ELLIE) system. This talk provides a summary of the upgrades to from SNO to SNO +, discussing the requirements on and methods of optical calibration, focusing on the deployed laserball and ELLIE system.

  14. Biomass Scenario Model Documentation: Data and References

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y.; Newes, E.; Bush, B.; Peterson, S.; Stright, D.

    2013-05-01

    The Biomass Scenario Model (BSM) is a system dynamics model that represents the entire biomass-to-biofuels supply chain, from feedstock to fuel use. The BSM is a complex model that has been used for extensive analyses; the model and its results can be better understood if input data used for initialization and calibration are well-characterized. It has been carefully validated and calibrated against the available data, with data gaps filled in using expert opinion and internally consistent assumed values. Most of the main data sources that feed into the model are recognized as baseline values by the industry. This report documents data sources and references in Version 2 of the BSM (BSM2), which only contains the ethanol pathway, although subsequent versions of the BSM contain multiple conversion pathways. The BSM2 contains over 12,000 total input values, with 506 distinct variables. Many of the variables are opportunities for the user to define scenarios, while others are simply used to initialize a stock, such as the initial number of biorefineries. However, around 35% of the distinct variables are defined by external sources, such as models or reports. The focus of this report is to provide insight into which sources are most influential in each area of the supply chain.

  15. Calibration of the ROSAT HRI Spectral Response

    Science.gov (United States)

    Prestwich, Andrea H.; Silverman, John; McDowell, Jonathan; Callanan, Paul; Snowden, Steve

    2000-01-01

    The ROSAT High Resolution Imager has a limited (2-band) spectral response. This spectral capability can give X-ray hardness ratios on spatial scales of 5 arcseconds. The spectral response of the center of the detector was calibrated before the launch of ROSAT, but the gain decreases with time and also is a function of position on the detector. To complicate matters further, the satellite is 'wobbled', possibly moving a source across several spatial gain states. These difficulties have prevented the spectral response of the ROSAT High Resolution Imager (HRI) from being used for scientific measurements. We have used Bright Earth data and in-flight calibration sources to map the spatial and temporal gain changes, and written software which will allow ROSAT users to generate a calibrated XSPEC (an x ray spectral fitting package) response matrix and hence determine a calibrated hardness ratio. In this report, we describe the calibration procedure and show how to obtain a response matrix. In Section 2 we give an overview of the calibration procedure, in Section 3 we give a summary of HRI spatial and temporal gain variations. Section 4 describes the routines used to determine the gain distribution of a source. In Sections 5 and 6, we describe in detail how, the Bright Earth database and calibration sources are used to derive a corrected response matrix for a given observation. Finally, Section 7 describes how to use the software.

  16. Technique for Radiometer and Antenna Array Calibration with a Radiated Noise Diode

    Science.gov (United States)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2009-01-01

    This paper presents a new technique to calibrate a microwave radiometer and antenna array system. This calibration technique uses a radiated noise source in addition to two calibration sources internal to the radiometer. The method accurately calibrates antenna arrays with embedded active devices (such as amplifiers) which are used extensively in active phased array antennas.

  17. WE-E-BRE-01: An Image-Based Skeletal Dosimetry Model for the ICRP Reference Adult Female - Internal Electron Sources

    Energy Technology Data Exchange (ETDEWEB)

    O' Reilly, S; Maynard, M; Marshall, E; Bolch, W [Department of Biomedical Engineering, University of Florida, Gainesville, FL (United States); Sinclair, L [Oregon Health and Science University, Portland, OR (United States); Rajon, D [Department of Neurosurgery, University of Florida, Gainesville, FL (United States); Wayson, M [Department of Radiology, University of Florida, Gainesville, FL (United States)

    2014-06-15

    Purpose: Limitations seen in previous skeletal dosimetry models, which are still employed in commonly used software today, include the lack of consideration of electron escape and cross-fire from cortical bone, the modeling of infinite spongiosa, the disregard of the effect of varying cellularity on active marrow self-irradiation, and the lack of use of the more recent ICRP definition of a 50 micron surrogate tissue region for the osteoprogenitor cells - shallow marrow. These limitations were addressed in the present dosimetry model. Methods: Electron transport was completed to determine specific absorbed fractions to active marrow and shallow marrow of the skeletal regions of the adult female. The bone macrostructure was obtained from the whole-body hybrid computational phantom of the UF series of reference phantoms, while the bone microstructure was derived from microCT images of skeletal region samples taken from a 45 year-old female cadaver. The target tissue regions were active marrow and shallow marrow. The source tissues were active marrow, inactive marrow, trabecular bone volume, trabecular bone surfaces, cortical bone volume and cortical bone surfaces. The marrow cellularity was varied from 10 to 100 percent for active marrow self-irradiation. A total of 33 discrete electron energies, ranging from 1 keV to 10 MeV, were either simulated or modeled analytically. Results: The method of combining macro- and microstructure absorbed fractions calculated using MCNPX electron transport was found to yield results similar to those determined with the PIRT model for the UF adult male in the Hough et al. study. Conclusion: The calculated skeletal averaged absorbed fractions for each source-target combination were found to follow similar trends of more recent dosimetry models (image-based models) and did not follow current models used in nuclear medicine dosimetry at high energies (due to that models use of an infinite expanse of trabecular spongiosa)

  18. Onic reference in discourse

    OpenAIRE

    Shilikhina, K.

    2011-01-01

    the paper discusses the relation between ironic nomination and the real world. Starting with a brief overview of existing theories of reference the paper explores various ways of ironic reference indefinite pronouns and noun phrases for pseudo-indefinite and definite reference respectively. Metalinguistic assessment of ironic reference is used as yet another source of information. Ironic nomination fulfills several functions: referentive, evaluative and regulative. The evaluative function bec...

  19. Evaluation of stormwater micropollutant source control and end-of-pipe control strategies using an uncertainty-calibrated integrated dynamic simulation model

    DEFF Research Database (Denmark)

    Vezzaro, Luca; Sharma, Anitha Kumari; Ledin, Anna

    2015-01-01

    The estimation of micropollutant (MP) fluxes in stormwater systems is a fundamental prerequisite when preparing strategies to reduce stormwater MP discharges to natural waters. Dynamic integrated models can be important tools in this step, as they can be used to integrate the limited data provided...... (copper, zinc) and organic compounds (fluoranthene). MP fluxes were estimated by using an integrated dynamic model, in combination with stormwater quality measurements. MP sources were identified by using GIS land usage data, runoff quality was simulated by using a conceptual accumulation/washoff model......, and a stormwater retention pond was simulated by using a dynamic treatment model based on MP inherent properties. Uncertainty in the results was estimated with a pseudo-Bayesian method. Despite the great uncertainty in the MP fluxes estimated by the runoff quality model, it was possible to compare the six...

  20. Synthesis Polarimetry Calibration

    Science.gov (United States)

    Moellenbrock, George

    2017-10-01

    Synthesis instrumental polarization calibration fundamentals for both linear (ALMA) and circular (EVLA) feed bases are reviewed, with special attention to the calibration heuristics supported in CASA. Practical problems affecting modern instruments are also discussed.

  1. Intercomparison of calibration procedures of high dose rate {sup 192} Ir sources in Brazil and a proposal of a new methodology; Intercomparacao de procedimientos de calibracao de fontes de {sup 192} Ir de alta taxa de dose no Brasil e proposta de uma nova metodologia

    Energy Technology Data Exchange (ETDEWEB)

    Marechal, M.H.; Almeida, C.E. de [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes IRD/CNEN. Caixa Postal 37750 CEP 22780-160 Rio de Janeiro (Brazil)

    1998-12-31

    The objective of this paper is to report the results of an intercomparison of the calibration procedures for {sup 192} Ir sources presently in use in Brazil and to proposal a calibration procedure to derive the N{sub k} for a Farmer type ionization chamber for {sup 192} Ir energy by interpolating from a {sup 60} Co gamma-rays and 250 kV x-rays calibration factors. the intercomparison results were all within {+-} 3.0 % except one case where 4.6 % was observed and latter identified as a problem with N-k value for X-rays. The method proposed by the present work make possible the improvement of the metrological coherence among the calibration laboratories and their users once the N{sub k} values could then provided by any of the members of SSDL network. (Author)

  2. Calibration and Rating of Photovoltaics: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Emery, K.

    2012-06-01

    Rating the performance of photovoltaic (PV) modules is critical to determining the cost per watt, and efficiency is useful to assess the relative progress among PV concepts. Procedures for determining the efficiency for PV technologies from 1-sun to low concentration to high concentration are discussed. We also discuss the state of the art in primary and secondary calibration of PV reference cells used by calibration laboratories around the world. Finally, we consider challenges to rating PV technologies and areas for improvement.

  3. Calibration of the Accuscan II In Vivo System for Whole Body Counting

    Energy Technology Data Exchange (ETDEWEB)

    Orval R. Perry; David L. Georgeson

    2011-08-01

    This report describes the April 2011 calibration of the Accuscan II HpGe In Vivo system for whole body counting. The source used for the calibration was a NIST traceable BOMAB manufactured by DOE as INL2006 BOMAB containing Eu-154, Eu-155, Eu-152, Sb-125 and Y-88 with energies from 27 keV to 1836 keV with a reference date of 11/29/2006. The actual usable energy range was 86.5 keV to 1597 keV on 4/21/2011. The BOMAB was constructed inside the Accuscan II counting 'tub' in the order of legs, thighs, abdomen, thorax/arms, neck, and head. Each piece was taped to the backwall of the counter. The arms were taped to the thorax. The phantom was constructed between the v-ridges on the backwall of the Accuscan II counter. The energy and efficiency calibrations were performed using the INL2006 BOMAB. The calibrations were performed with the detectors in the scanning mode. This report includes an overview introduction and records for the energy/FWHM and efficiency calibration including performance verification and validation counting. The Accuscan II system was successfully calibrated for whole body counting and verified in accordance with ANSI/HPS N13.30-1996 criteria.

  4. Calibration of Ground-based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference 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 wind vanes...

  5. Calibration of Ground -based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Yordanova, Ginka

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference 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 wind vanes...

  6. Calibrators and control samples for bilirubinometers.

    Science.gov (United States)

    Blijenberg, B G; Brügmann, G; Geilenkeuser, W J; Kusyschyn, R; Röhle, G; Schlebusch, H; Schneider, C

    1993-06-01

    The different matrix properties of neonatal serum and commercial control samples can lead to considerable errors in the calibration and control of bilirubinometers. These difficulties can be avoided by calibration with serum from healthy adults which is supplemented with unconjugated bilirubin. But this procedure is impracticable for most routine laboratories. Under certain preconditions, control samples, with bilirubin concentrations determined with correctly calibrated bilirubinometers or spectrophotometers, are also suitable as calibrators. This was established by determination of the bilirubin concentration of 16 different control samples, using both the reference method and correctly calibrated bilirubinometers or spectrophotometers in three or four specialist laboratories. This was also confirmed in several interlaboratory surveys, some involving up to 72 laboratories. The results of these investigations show that a control sample should be used for the calibration of a bilirubinometer only if it meets the following preconditions: 1. There should be no significant difference between the bilirubin values determined with the reference method and with a correctly calibrated spectrophotometer or bilirubinometer. 2. The bilirubin concentration should lie in the range 230-300 mumol/l. The photometric response of bilirubinometers has a limited linear range, so that analytical results greater than 300 mumol/l must be rated as basically unreliable.

  7. Reference gene screening for analyzing gene expression across goat tissue.

    Science.gov (United States)

    Zhang, Yu; Zhang, Xiao-Dong; Liu, Xing; Li, Yun-Sheng; Ding, Jian-Ping; Zhang, Xiao-Rong; Zhang, Yun-Hai

    2013-12-01

    Real-time quantitative PCR (qRT-PCR) is one of the important methods for investigating the changes in mRNA expression levels in cells and tissues. Selection of the proper reference genes is very important when calibrating the results of real-time quantitative PCR. Studies on the selection of reference genes in goat tissues are limited, despite the economic importance of their meat and dairy products. We used real-time quantitative PCR to detect the expression levels of eight reference gene candidates (18S, TBP, HMBS, YWHAZ, ACTB, HPRT1, GAPDH and EEF1A2) in ten tissues types sourced from Boer goats. The optimal reference gene combination was selected according to the results determined by geNorm, NormFinder and Bestkeeper software packages. The analyses showed that tissue is an important variability factor in genes expression stability. When all tissues were considered, 18S, TBP and HMBS is the optimal reference combination for calibrating quantitative PCR analysis of gene expression from goat tissues. Dividing data set by tissues, ACTB was the most stable in stomach, small intestine and ovary, 18S in heart and spleen, HMBS in uterus and lung, TBP in liver, HPRT1 in kidney and GAPDH in muscle. Overall, this study provided valuable information about the goat reference genes that can be used in order to perform a proper normalisation when relative quantification by qRT-PCR studies is undertaken.

  8. Reference Gene Screening for Analyzing Gene Expression Across Goat Tissue

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    2013-12-01

    Full Text Available Real-time quantitative PCR (qRT-PCR is one of the important methods for investigating the changes in mRNA expression levels in cells and tissues. Selection of the proper reference genes is very important when calibrating the results of real-time quantitative PCR. Studies on the selection of reference genes in goat tissues are limited, despite the economic importance of their meat and dairy products. We used real-time quantitative PCR to detect the expression levels of eight reference gene candidates (18S, TBP, HMBS, YWHAZ, ACTB, HPRT1, GAPDH and EEF1A2 in ten tissues types sourced from Boer goats. The optimal reference gene combination was selected according to the results determined by geNorm, NormFinder and Bestkeeper software packages. The analyses showed that tissue is an important variability factor in genes expression stability. When all tissues were considered, 18S, TBP and HMBS is the optimal reference combination for calibrating quantitative PCR analysis of gene expression from goat tissues. Dividing data set by tissues, ACTB was the most stable in stomach, small intestine and ovary, 18S in heart and spleen, HMBS in uterus and lung, TBP in liver, HPRT1 in kidney and GAPDH in muscle. Overall, this study provided valuable information about the goat reference genes that can be used in order to perform a proper normalisation when relative quantification by qRT-PCR studies is undertaken.

  9. Air kerma and absorbed dose standards for reference dosimetry in brachytherapy

    Science.gov (United States)

    2014-01-01

    This article reviews recent developments in primary standards for the calibration of brachytherapy sources, with an emphasis on the currently most common photon-emitting radionuclides. The introduction discusses the need for reference dosimetry in brachytherapy in general. The following section focuses on the three main quantities, i.e. reference air kerma rate, air kerma strength and absorbed dose rate to water, which are currently used for the specification of brachytherapy photon sources and which can be realized with primary standards from first principles. An overview of different air kerma and absorbed dose standards, which have been independently developed by various national metrology institutes over the past two decades, is given in the next two sections. Other dosimetry techniques for brachytherapy will also be discussed. The review closes with an outlook on a possible transition from air kerma to absorbed dose to water-based calibrations for brachytherapy sources in the future. PMID:24814696

  10. 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.

  11. Automated correction on X-rays calibration using transmission chamber and LabVIEW{sup TM}

    Energy Technology Data Exchange (ETDEWEB)

    Betti, Flavio; Potiens, Maria da Penha Albuquerque, E-mail: fbetti@ipen.b, E-mail: mppalbu@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    Uncertainties during prolonged exposure times on X-rays calibration procedures at the Instruments Calibration facilities at IPEN may suffer from efficiency (and therefore intensity) variations on the industrial X-Ray generator used. Using a transmission chamber as an online reference chamber during the whole irradiation process is proposed in order to compensate for such error source. Also temperature (and pressure) fluctuations may arise from the performance limited calibration room air conditioning system. As an open ionization chamber, that monitor chamber does require calculation of a correction factor due to the temperature and pressure effects on air density. Sending and processing data from all related instruments (electrometer, thermometer and barometer) can be more easily achieved by interfacing them to a host computer running an especially developed algorithm using LabVIEW{sup TM} environment which will not only apply the proper correction factors during runtime, but also determine the exact length of time to reach a desired condition, which can be: time period, charge collected, or air kerma, based on the previous calibration of the whole system using a reference chamber traceable to primary standard dosimetry laboratories. When performing such calibration, two temperature sensors (secondary standard thermistors) are simultaneously used, one for the transmission chamber, and other for the reference chamber. As the substitution method is used during actual customer's calibration, the readings from the second thermistor can also be used when desired for further corrections. Use of LabVIEW{sup TM} programming language allowed for a shorter development time, and it is also extremely convenient to make things easier when improvements and modifications are called for. (author)

  12. Pyrgeometer calibration at the National Renewable Energy Laboratory (NREL)

    Science.gov (United States)

    Reda, Ibrahim; Hickey, John R.; Stoffel, Tom; Myers, Daryl

    2002-10-01

    Pyrgeometers are used to measure longwave terrestrial radiation. Regular pyrgeometer calibration against an internationally recognized standard is required in order to measure the longwave radiation consistently at different sites around the globe. At present, there is no internationally recognized standard to calibrate pyrgeometers. A well-characterized blackbody is, however, an accepted approach. This paper describes a method of establishing a precise blackbody reference and using it to calibrate a group of four transfer reference pyrgeometers. The group is then deployed outdoors to evaluate the precision of the blackbody calibration. The results from the outdoor data shows that the percentage mean-square-error of each transfer reference pyrgeometer is 0.12%, 0.07%, 0.46%, and 0.10% with a resultant percentage root-mean-square of 0.43%. The errors are calculated with respect to the average of the irradiance readings of the transfer reference pyrgeometers. To minimize the number of transfer reference pyrgeometers and to allow more space for calibrating test pyrgeometers, a sub-set of the transfer reference pyrgeometers is then used to calibrate a test pyrgeometer outdoors. The calibration of the test pyrgeometer resulted in reducing its error from /+4.00% to /+/-0.32% with respect to the irradiance measured by the sub-set of the transfer reference pyrgeometers. The outdoor calibration method can minimize the calibration cost resulting from using the lengthy and costly blackbody calibration because many pyrgeometers can be calibrated at the same time. Appendix A shows a diagram that describes the paper's concept.

  13. Scalar Calibration of Vector Magnetometers

    DEFF Research Database (Denmark)

    Merayo, José M.G.; Brauer, Peter; Primdahl, Fritz

    2000-01-01

    The calibration parameters of a vector magnetometer are estimated only by the use of a scalar reference magnetometer. The method presented in this paper differs from those previously reported in its linearized parametrization. This allows the determination of three offsets or signals in the absence...... of a magnetic field, three scale factors for normalization of the axes and three non-orthogonality angles which build up an orthogonal system intrinsically in the sensor. The advantage of this method compared with others lies in its linear least squares estimator, which finds independently and uniquely...... the parameters for a given data set. Therefore, a magnetometer may be characterized inexpensively in the Earth's magnetic-field environment. This procedure has been used successfully in the pre-flight calibration of the state-of-the-art magnetometers on board the magnetic mapping satellites Orsted, Astrid-2...

  14. Estimation of Completeness of Cancer Registration for Patients Referred to Shiraz Selected Centers through a Two Source Capture Re-capture Method, 2009 Data.

    Science.gov (United States)

    Sharifian, Roxana; SedaghatNia, Mohammad Hossein; Nematolahi, Mohtram; Zare, Najaf; Barzegari, Saeed

    2015-01-01

    Cancer has important social consequences with cancer registration as the basis of moving towards prevention. The present study aimed to estimate the completeness of registration of the ten most common cancers in patients referred to selected hospitals in Shiraz, Iran by using capture-recapture method. This cross-sectional analytical study was performed in 2014 based on the data of 2009, on a total of 4,388 registered cancer patients. After cleaning data from two sources, using capture-recapture common findings were identified. Then, the percentage of the completeness of cancer registration was estimated using Chapman and Chao methods. Finally, the effects of demographic and treatment variables on the completeness of cancer registration were investigated. The results showed that the percentages of completeness of cancer registration in the selected hospitals of Shiraz were 58.6% and 58.4%, and influenced by different variables. The age group between 40-49 years old was the highest represented and for the age group under 20 years old was the lowest for cancer registration. Breast cancer had the highest registration level and after that, thyroid and lung cancers, while colorectal cancer had the lowest registration level. According to the results, the number of cancers registered was very few and it seems that factors like inadequate knowledge of some doctors, imprecise diagnosis about the types of cancer, incorrectly filled out medical documents, and lack of sufficient accuracy in recording data on the computer cause errors and defects in cancer registration. This suggests a necessity to educate and teach doctors and other medical workers about the methods of documenting information related to cancer and also conduct additional measures to improve the cancer registration system.

  15. 3D artefact for concurrent scale calibration in Computed Tomography

    DEFF Research Database (Denmark)

    Stolfi, Alessandro; De Chiffre, Leonardo

    2016-01-01

    A novel artefact for calibration of the scale in 3D X-ray Computed Tomography (CT) is presented. The artefact comprises a carbon fibre tubular structure on which a number of reference ruby spheres are glued. The artefact is positioned and scanned together with the workpiece inside the CT scanner...... providing a reference system for measurement. The artefact allows a considerable reduction of time by compressing the full process of calibration, scanning, measurement, and re-calibration, into a single process. The method allows a considerable reduction of the amount of data generated from CT scanning....... A prototype was calibrated and its applicability demonstrated....

  16. SMAP RADAR Processing and Calibration

    Science.gov (United States)

    West, R. D.; Jaruwatanadilok, S.; Kwoun, O.; Chaubell, M. J.

    2013-12-01

    The Soil Moisture Active Passive (SMAP) mission uses L-band radar and radiometer measurements to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Model sensitivities translate the soil moisture accuracy to a radar backscatter accuracy of 1 dB at 3 km resolution and a brightness temperature accuracy of 1.3 K at 40 km resolution. This presentation will describe the level 1 radar processing and calibration challenges and the choices made so far for the algorithms and software implementation. To obtain the desired high spatial resolution the level 1 radar ground processor employs synthetic aperture radar (SAR) imaging techniques. Part of the challenge of the SMAP data processing comes from doing SAR imaging on a conically scanned system with rapidly varying squint angles. The radar echo energy will be divided into range/Doppler bins using time domain processing algorithms that can easily follow the varying squint angle. For SMAP, projected range resolution is about 250 meters, while azimuth resolution varies from 400 meters to 1.2 km. Radiometric calibration of the SMAP radar means measuring, characterizing, and where necessary correcting the gain and noise contributions from every part of the system from the antenna radiation pattern all the way to the ground processing algorithms. The SMAP antenna pattern will be computed using an accurate antenna model, and then validated post-launch using homogeneous external targets such as the Amazon rain forest to look for uncorrected gain variation. Noise subtraction is applied after image processing using measurements from a noise only channel. Variations of the internal electronics are tracked by a loopback measurement which will capture most of the time and temperature variations of the transmit power and receiver gain. Long-term variations of system performance due to component aging will be tracked and corrected using stable external reference

  17. Improving photometric calibration of meteor video camera systems

    Science.gov (United States)

    Ehlert, Steven; Kingery, Aaron; Suggs, Robert

    2017-09-01

    We present the results of new calibration tests performed by the NASA Meteoroid Environment Office (MEO) designed to help quantify and minimize systematic uncertainties in meteor photometry from video camera observations. These systematic uncertainties can be categorized by two main sources: an imperfect understanding of the linearity correction for the MEO's Watec 902H2 Ultimate video cameras and uncertainties in meteor magnitudes arising from transformations between the Watec camera's Sony EX-View HAD bandpass and the bandpasses used to determine reference star magnitudes. To address the first point, we have measured the linearity response of the MEO's standard meteor video cameras using two independent laboratory tests on eight cameras. Our empirically determined linearity correction is critical for performing accurate photometry at low camera intensity levels. With regards to the second point, we have calculated synthetic magnitudes in the EX bandpass for reference stars. These synthetic magnitudes enable direct calculations of the meteor's photometric flux within the camera bandpass without requiring any assumptions of its spectral energy distribution. Systematic uncertainties in the synthetic magnitudes of individual reference stars are estimated at ∼ 0.20 mag , and are limited by the available spectral information in the reference catalogs. These two improvements allow for zero-points accurate to ∼ 0.05 - 0.10 mag in both filtered and unfiltered camera observations with no evidence for lingering systematics. These improvements are essential to accurately measuring photometric masses of individual meteors and source mass indexes.

  18. Selection of Reference Genes for Quantitative Gene Expression in Porcine Mesenchymal Stem Cells Derived from Various Sources along with Differentiation into Multilineages

    Directory of Open Access Journals (Sweden)

    Won-Jae Lee

    2015-01-01

    Full Text Available The identification of stable reference genes is a prerequisite for ensuring accurate validation of gene expression, yet too little is known about stable reference genes of porcine MSCs. The present study was, therefore, conducted to assess the stability of reference genes in porcine MSCs derived from bone marrow (BMSCs, adipose (AMSCs, and skin (SMSCs with their in vitro differentiated cells into mesenchymal lineages such as adipocytes, osteocytes, and chondrocytes. Twelve commonly used reference genes were investigated for their threshold cycle (Ct values by qRT-PCR. The Ct values of candidate reference genes were analyzed by geNorm software to clarify stable expression regardless of experimental conditions. Thus, Pearson’s correlation was applied to determine correlation between the three most stable reference genes (NF3 and optimal number of reference genes (NFopt. In assessment of stability of reference gene across experimental conditions by geNorm analysis, undifferentiated MSCs and each differentiated status into mesenchymal lineages showed slightly different results but similar patterns about more or less stable rankings. Furthermore, Pearson’s correlation revealed high correlation (r>0.9 between NF3 and NFopt. Overall, the present study showed that HMBS, YWHAZ, SDHA, and TBP are suitable reference genes for qRT-PCR in porcine MSCs.

  19. Calibration of the JEM-EUSO detector

    Directory of Open Access Journals (Sweden)

    Gorodetzky P.

    2013-06-01

    Full Text Available In order to unveil the mystery of ultra high energy cosmic rays (UHECRs, JEM-EUSO (Extreme Universe Space Observatory on-board Japan Experiment Module will observe extensive air showers induced by UHECRs from the International Space Station orbit with a huge acceptance. Calibration of the JEM-EUSO instrument, which consists of Fresnel optics and a focal surface detector with 5000 photomultipliers, is very important to discuss the origin of UHECRs precisely with the observed results. In this paper, the calibration before launch and on-orbit is described. The calibration before flight will be performed as precisely as possible with integrating spheres. In the orbit, the relative change of the performance will be checked regularly with on-board and on-ground light sources. The absolute calibration of photon detection efficiency may be performed with the moon, which is a stable light source in the nature.

  20. Calibration Systems of the ATLAS Tile Calorimeter

    CERN Document Server

    Lundberg, O

    2013-01-01

    TileCal is the hadronic calorimeter covering the most central region of the ATLAS experiment at the LHC. This sampling calorimeter uses iron plates as absorber and plastic scintillating tiles as the active material. A multi-faceted calibration system allows to monitor and equalize the calorimeter response at each stage of the signal production, from scintillation light to digitization. This calibration system is based on signal generation from different sources: a Cs radioactive source, laser light, charge injection and minimum bias events produced in proton-proton collisions. A brief description of the different TileCal calibration systems is given and the latest results on their performance in terms of calibration factors, linearity and stability are presented.

  1. Calibration systems of the ATLAS Tile Calorimeter

    CERN Document Server

    Lundberg, O; The ATLAS collaboration

    2012-01-01

    TileCal is the hadronic calorimeter covering the most central region of the ATLAS experiment at the LHC. This sampling calorimeter uses iron plates as absorber and plastic scintillating tiles as the active material. Scintillation light produced in the tiles is transmitted by wavelength shifting fibers to photomultiplier tubes (PMTs). The resulting electronic signals from the over 10000 PMTs are measured and digitized before being transferred to off-detector data-acquisition systems. A multi-faceted calibration system allows to monitor and equalize the calorimeter response at each stage of the signal production, from scintillation light to digitization. This calibration system is based on signal generation from different sources: a Cs radioactive source, laser light, charge injection and minimum bias events produced in proton-proton collisions. This talk presents a brief description of the different TileCal calibration systems and presents the latest results on their performance in terms of calibration factors...

  2. Precision alignment and calibration of optical systems using computer generated holograms

    Science.gov (United States)

    Coyle, Laura Elizabeth

    As techniques for manufacturing and metrology advance, optical systems are being designed with more complexity than ever before. Given these prescriptions, alignment and calibration can be a limiting factor in their final performance. Computer generated holograms (CGHs) have several unique properties that make them powerful tools for meeting these demanding tolerances. This work will present three novel methods for alignment and calibration of optical systems using computer generated holograms. Alignment methods using CGHs require that the optical wavefront created by the CGH be related to a mechanical datum to locate it space. An overview of existing methods is provided as background, then two new alignment methods are discussed in detail. In the first method, the CGH contact Ball Alignment Tool (CBAT) is used to align a ball or sphere mounted retroreflector (SMR) to a Fresnel zone plate pattern with micron level accuracy. The ball is bonded directly onto the CGH substrate and provides permanent, accurate registration between the optical wavefront and a mechanical reference to locate the CGH in space. A prototype CBAT was built and used to align and bond an SMR to a CGH. In the second method, CGH references are used to align axi-symmetric optics in four degrees of freedom with low uncertainty and real time feedback. The CGHs create simultaneous 3D optical references where the zero order reflection sets tilt and the first diffracted order sets centration. The flexibility of the CGH design can be used to accommodate a wide variety of optical systems and maximize sensitivity to misalignments. A 2-CGH prototype system was aligned multiplied times and the alignment uncertainty was quantified and compared to an error model. Finally, an enhanced calibration method is presented. It uses multiple perturbed measurements of a master sphere to improve the calibration of CGH-based Fizeau interferometers ultimately measuring aspheric test surfaces. The improvement in the

  3. LBCS: The LOFAR long-baseline calibrator survey

    NARCIS (Netherlands)

    Jackson, N.; Tagore, A.; Deller, A.; Moldon, J.; Varenius, E.; Morabito, L.; Bentum, Marinus Jan; Wucknitz, O.; Carozzi, T.; Conway, J.

    2016-01-01

    We outline the LOFAR Long-Baseline Calibrator Survey (LBCS), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines >1000 km. Suitable sources must contain significant correlated flux density

  4. 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...

  5. A practical implementation of microphone free-field comparison calibration according to the standard IEC 61094-8

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Torras-Rosell, Antoni; Rasmussen, Knud

    2012-01-01

    . The two methodologies assume that the two microphones are exposed to the same sound pressure. This can be achieved by measuring the ratio of output voltages either sequentially or simultaneously. The first method requires a stable source to ensure that the sound pressure is approximately the same when...... the reference and test microphones are measured, whereas the second requires a source with a symmetrical directivity that ensures that the microphones placed at opposite positions are subjected to the same sound pressure. The two methods have been investigated experimentally in an extended frequency range......An international standard concerned with the calibration of microphones in a free field by comparison has recently been published. The standard contemplates two main calibration methodologies for determining the sensitivity of a microphone under test when compared against a reference microphone...

  6. Reference citation

    National Research Council Canada - National Science Library

    Brkić, Silvija

    2013-01-01

    .... This paper deals with different styles of reference citation. Special emphasis was placed on the Vancouver Style for reference citation in biomedical journals established by the International Committee of Medical Journal Editors...

  7. Calibration of a large-scale hydrological model using satellite-based soil moisture and evapotranspiration products

    Science.gov (United States)

    López López, Patricia; Sutanudjaja, Edwin H.; Schellekens, Jaap; Sterk, Geert; Bierkens, Marc F. P.

    2017-06-01

    A considerable number of river basins around the world lack sufficient ground observations of hydro-meteorological data for effective water resources assessment and management. Several approaches can be developed to increase the quality and availability of data in these poorly gauged or ungauged river basins; among them, the use of Earth observations products has recently become promising. Earth observations of various environmental variables can be used potentially to increase knowledge about the hydrological processes in the basin and to improve streamflow model estimates, via assimilation or calibration. The present study aims to calibrate the large-scale hydrological model PCRaster GLOBal Water Balance (PCR-GLOBWB) using satellite-based products of evapotranspiration and soil moisture for the Moroccan Oum er Rbia River basin. Daily simulations at a spatial resolution of 5 × 5 arcmin are performed with varying parameters values for the 32-year period 1979-2010. Five different calibration scenarios are inter-compared: (i) reference scenario using the hydrological model with the standard parameterization, (ii) calibration using in situ-observed discharge time series, (iii) calibration using the Global Land Evaporation Amsterdam Model (GLEAM) actual evapotranspiration time series, (iv) calibration using ESA Climate Change Initiative (CCI) surface soil moisture time series and (v) step-wise calibration using GLEAM actual evapotranspiration and ESA CCI surface soil moisture time series. The impact on discharge estimates of precipitation in comparison with model parameters calibration is investigated using three global precipitation products, including ERA-Interim (EI), WATCH Forcing methodology applied to ERA-Interim reanalysis data (WFDEI) and Multi-Source Weighted-Ensemble Precipitation data by merging gauge, satellite and reanalysis data (MSWEP). Results show that GLEAM evapotranspiration and ESA CCI soil moisture may be used for model calibration resulting in

  8. Développement d’un système de mesure directe du débit d’émission de sources neutroniques

    OpenAIRE

    Ogheard, Florestan

    2012-01-01

    The manganese bath technique is the reference method for neutron source emission rates calibration. It is used to calibrate neutron sources using radionuclides (AmBe, PuBe, 252Cf,…) in terms of neutron emission rate under 4π sr. As a complement to this technique, the anisotropy of the source is measured using a rotating source holder and a neutron long counter. The neutron source to be measured is immersed in a manganese sulphate solution whereby the emitted neutrons are captured within the b...

  9. In situ calibration technique for UV spectral radiometers.

    Science.gov (United States)

    Wilson, S R; Forgan, B W

    1995-08-20

    A technique for calibrating spectral radiometers measuring global (2π sr) irradiance using solar irradiance at the top of the atmosphere as the absolute irradiance reference is reported. In addition to providing a calibration at all measured wavelengths, the technique provides a direct measure of the angular response of the radiometer. For instruments that can be used to measure the ultraviolet-B region, the calibration also provides an estimate of the ozone column amount.

  10. 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.

  11. Energy Calibration of Double Chooz Detector

    Science.gov (United States)

    Yang, Guang

    2013-04-01

    Reactor anti-neutrino oscillation experiment Double Chooz was designed to measure the mixing angle theta-13 with unprecedented sensitivity. The Double Chooz detector system consists of a main detector, an outer veto system and several calibration systems. The main detector has a cylindrical structure. It consists of the target vessel, a liquid scintillator loaded with Gd, surrounded by the gamma-catcher, a non-loaded liquid scintillator. A buffer region of non-scintillating liquid surrounds the gamma-catcher and serves to host 390 photomultiplier tubes and to decrease the level of accidental background. The Inner Veto region is outside the buffer, and the Outer Veto system covers all detector components. Far detector is operational and the near detector is under construction. The detector is calibrated with light sources, radioactive point sources, cosmics and natural radioactivity. In this presentation we will describe use of radioactive calibration sources and cross-checks performed with cosmics and natural radioactivity.

  12. Site Calibration report

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Vesth, Allan

    This report describes the site calibration carried out at Østerild, during a given period. The site calibration was performed with two Windcube WLS7 (v1) lidars at ten measurements heights. The lidar is not a sensor approved by the current version of the IEC 61400-12-1 [1] and therefore the site...

  13. TWSTFT Link Calibration Report

    Science.gov (United States)

    2015-09-01

    Washington Headquarters Services , Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302...and Bauch A (2014) THE EUROPEAN TW CALIBRATION CAMPAIGN 2014 IN THE SCOPE OF GALILEO (TGVF- FOC), An opportunity to update, TW link calibrations in

  14. In-flight radiometric calibration of the Advanced Land Imager and Hyperion sensors on the EO-1 platform and comparisons with other earth observing sensors

    Science.gov (United States)

    Biggar, Stuart F.; Thome, Kurtis J.; Wisniewski, Wit T.

    2002-09-01

    The radiometric calibration of the two optical sensors on the Earth Observing One satellite has been studied as a function of time since launch. The calibration has been determined by ground reference calibrations at well-characterized field sites, such as White Sands Missile Range and dry playas, and by reference to other sensors such as the Enhanced Thematic Mapper Plus (ETM+) on Landsat 7. The ground reference calibrations of the Advanced Land Imager (ALI) give results consistent with the on-board solar calibrator and show a significant shift since preflight calibration in the short wavelength bands. Similarly, the ground reference calibrations of Hyperion show a change since preflight calibration, however, for Hyperion the largest changes are in the short wave infrared region of the spectrum. Cross calibration of ALI with ETM+ is consistent with the ground reference calibrations in the visible and near infrared. Results showing the changes in radiometric calibration are presented.

  15. 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.

  16. A compact soft x-ray (0.1-1.2 keV) calibration bench for radiometric measurements using an original versatile Rowland circle grazing incidence monochromator

    Science.gov (United States)

    Hubert, S.

    2017-05-01

    This paper describes an original Rowland circle grazing incidence spectrometer used as a monochromator for a soft x-ray Manson source in order to calibrate both the source and detectors over the 0.1-1.2 keV spectral range. The originality of the instrument lies on a patented vacuum manipulator which allows the simultaneous boarding of two detectors, one (reference) for measuring the monochromatic radiation and the second to be calibrated. In order to achieve this, the vacuum manipulator is able to interchange, in vacuum, one detector with the other in front of the exit slit of the monochromatizing stage. One purpose of this apparatus was to completely eliminate the intrinsic bremsstrahlung emission of the x-ray diode source and isolate each characteristic line for quantitative detector calibrations. Obtained spectral resolution (Δλ/λ98%) fully meet this objective. Initially dimensioned to perform calibration of bulky x-ray cameras unfolded on the Laser MégaJoule Facility, other kinds of detector can be obviously calibrated using this instrument. A brief presentation of the first calibration of an x-ray CCD through its quantum efficiency (QE) measurement is included in this paper as example. Comparison with theoretical model for QE and previous measurements at higher energy are finally presented and discussed.

  17. Lidar to lidar calibration of Ground-based Lidar

    DEFF Research Database (Denmark)

    Fernandez Garcia, Sergio; Courtney, Michael

    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 correspondi...

  18. Calorimeter energy calibration using the energy conservation law

    Indian Academy of Sciences (India)

    A new calorimeter energy calibration method was developed for the proposed ILC detectors. The method uses the center-of-mass energy of the accelerator as the reference. It has been shown that using the energy conservation law it is possible to make ECAL and HCAL cross calibration to reach a good energy resolution ...

  19. In-situ Calibration of Ground -based Lidar instrument

    DEFF Research Database (Denmark)

    Georgieva Yankova, Ginka; Villanueva, Héctor

    This report presents the result of the lidar in-situ calibration performed at DTU’s test site for large wind turbine at Østerild, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement uncertainties provided by mea...

  20. Radiometer calibration methods and resulting irradiance differences: Radiometer calibration methods and resulting irradiance differences

    Energy Technology Data Exchange (ETDEWEB)

    Habte, Aron [National Renewable Energy Laboratory, Golden CO 80401 USA; Sengupta, Manajit [National Renewable Energy Laboratory, Golden CO 80401 USA; Andreas, Afshin [National Renewable Energy Laboratory, Golden CO 80401 USA; Reda, Ibrahim [National Renewable Energy Laboratory, Golden CO 80401 USA; Robinson, Justin [GroundWork Renewables Inc., Logan UT 84321 USA

    2016-10-07

    Accurate solar radiation measured by radiometers depends on instrument performance specifications, installation method, calibration procedure, measurement conditions, maintenance practices, location, and environmental conditions. This study addresses the effect of different calibration methodologies and resulting differences provided by radiometric calibration service providers such as the National Renewable Energy Laboratory (NREL) and manufacturers of radiometers. Some of these methods calibrate radiometers indoors and some outdoors. To establish or understand the differences in calibration methodologies, we processed and analyzed field-measured data from radiometers deployed for 10 months at NREL's Solar Radiation Research Laboratory. These different methods of calibration resulted in a difference of +/-1% to +/-2% in solar irradiance measurements. Analyzing these differences will ultimately assist in determining the uncertainties of the field radiometer data and will help develop a consensus on a standard for calibration. Further advancing procedures for precisely calibrating radiometers to world reference standards that reduce measurement uncertainties will help the accurate prediction of the output of planned solar conversion projects and improve the bankability of financing solar projects.

  1. Herschel SPIRE FTS relative spectral response calibration

    Science.gov (United States)

    Fulton, Trevor; Hopwood, Rosalind; Baluteau, Jean-Paul; Benielli, Dominique; Imhof, Peter; Lim, Tanya; Lu, Nanyao; Marchili, Nicola; Naylor, David; Polehampton, Edward; Swinyard, Bruce; Valtchanov, Ivan

    2014-07-01

    Herschel/SPIRE Fourier transform spectrometer (FTS) observations contain emission from both the Herschel Telescope and the SPIRE Instrument itself, both of which are typically orders of magnitude greater than the emission from the astronomical source, and must be removed in order to recover the source spectrum. The effects of the Herschel Telescope and the SPIRE Instrument are removed during data reduction using relative spectral response calibration curves and emission models. We present the evolution of the methods used to derive the relative spectral response calibration curves for the SPIRE FTS. The relationship between the calibration curves and the ultimate sensitivity of calibrated SPIRE FTS data is discussed and the results from the derivation methods are compared. These comparisons show that the latest derivation methods result in calibration curves that impart a factor of between 2 and 100 less noise to the overall error budget, which results in calibrated spectra for individual observations whose noise is reduced by a factor of 2-3, with a gain in the overall spectral sensitivity of 23 % and 21 % for the two detector bands, respectively.

  2. Relative vs Absolute Antenna Calibrations: How, when, and why do they differ? A Comparison of Antenna Calibration Catalogs

    Science.gov (United States)

    Mader, G. L.; Bilich, A. L.

    2013-12-01

    Since 1994, NGS has computed relative antenna calibrations for more than 350 antenna models used by NGS customers and geodetic networks worldwide. In a 'relative' calibration, the antenna under test is calibrated relative to a standard reference antenna, the AOA D/M_T chokering. The majority of NGS calibrations have been made publicly available at the web site www.ngs.noaa.gov/ANTCAL as well as via the NGS master calibrations file ant_info.003. In the mid-2000's, institutions in Germany began distributing 'absolute' antenna calibrations, where the antenna under test is calibrated independent of any reference antenna. These calibration methods also overcame some limitations of relative calibrations by going to lower elevation angles and capturing azimuthal variations. Soon thereafter (2008), the International GNSS Service (IGS) initiated a geodetic community movement away from relative calibrations and toward absolute calibrations as the defacto standard. The IGS now distributes a catalog of absolute calibrations taken from several institutions, distributed as the IGS master calibrations file igs08.atx. The competing methods and files have raised many questions about when it is or is not valid to process a geodetic network using a combination of relative and absolute calibrations, and if/when it is valid to combine the NGS and IGS catalogs. Therefore, in this study, we compare the NGS catalog of relative calibrations against the IGS catalog of absolute calibrations. As of the writing of this abstract, there are 77 antenna+radome combinations which are common to both the NGS relative and IGS absolute catalogs, spanning 16 years of testing (1997 to present). 50 different antenna models and 8 manufacturers are represented in the study sample. We apply the widely-accepted standard method for converting relative to absolute, then difference the calibrations. Various statistics describe the observed differences between phase center offset (PCO), phase center variation

  3. SMAP RADAR Calibration and Validation

    Science.gov (United States)

    West, R. D.; Jaruwatanadilok, S.; Chaubel, M. J.; Spencer, M.; Chan, S. F.; Chen, C. W.; Fore, A.

    2015-12-01

    The Soil Moisture Active Passive (SMAP) mission launched on Jan 31, 2015. The mission employs L-band radar and radiometer measurements to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Immediately following launch, there was a three month instrument checkout period, followed by six months of level 1 (L1) calibration and validation. In this presentation, we will discuss the calibration and validation activities and results for the L1 radar data. Early SMAP radar data were used to check commanded timing parameters, and to work out issues in the low- and high-resolution radar processors. From April 3-13 the radar collected receive only mode data to conduct a survey of RFI sources. Analysis of the RFI environment led to a preferred operating frequency. The RFI survey data were also used to validate noise subtraction and scaling operations in the radar processors. Normal radar operations resumed on April 13. All radar data were examined closely for image quality and calibration issues which led to improvements in the radar data products for the beta release at the end of July. Radar data were used to determine and correct for small biases in the reported spacecraft attitude. Geo-location was validated against coastline positions and the known positions of corner reflectors. Residual errors at the time of the beta release are about 350 m. Intra-swath biases in the high-resolution backscatter images are reduced to less than 0.3 dB for all polarizations. Radiometric cross-calibration with Aquarius was performed using areas of the Amazon rain forest. Cross-calibration was also examined using ocean data from the low-resolution processor and comparing with the Aquarius wind model function. Using all a-priori calibration constants provided good results with co-polarized measurements matching to better than 1 dB, and cross-polarized measurements matching to about 1 dB in the beta release. During the

  4. Improving Photometric Calibration of Meteor Video Camera Systems

    Science.gov (United States)

    Ehlert, Steven; Kingery, Aaron; Suggs, Robert

    2016-01-01

    We present the results of new calibration tests performed by the NASA Meteoroid Environment Oce (MEO) designed to help quantify and minimize systematic uncertainties in meteor photometry from video camera observations. These systematic uncertainties can be categorized by two main sources: an imperfect understanding of the linearity correction for the MEO's Watec 902H2 Ultimate video cameras and uncertainties in meteor magnitudes arising from transformations between the Watec camera's Sony EX-View HAD bandpass and the bandpasses used to determine reference star magnitudes. To address the rst point, we have measured the linearity response of the MEO's standard meteor video cameras using two independent laboratory tests on eight cameras. Our empirically determined linearity correction is critical for performing accurate photometry at low camera intensity levels. With regards to the second point, we have calculated synthetic magnitudes in the EX bandpass for reference stars. These synthetic magnitudes enable direct calculations of the meteor's photometric ux within the camera band-pass without requiring any assumptions of its spectral energy distribution. Systematic uncertainties in the synthetic magnitudes of individual reference stars are estimated at 0:20 mag, and are limited by the available spectral information in the reference catalogs. These two improvements allow for zero-points accurate to 0:05 ?? 0:10 mag in both ltered and un ltered camera observations with no evidence for lingering systematics.

  5. Identification of a common reference gene pair for qPCR in human mesenchymal stromal cells from different tissue sources treated with VEGF

    DEFF Research Database (Denmark)

    Tratwal, Josefine; Follin, Bjarke; Ekblond, Annette

    2014-01-01

    for both BMSCs and ASCs. The optimal number of RGs for ASCs was two, and the lowest variance for vWF normalization was found using TBP and YWHAZ. For BMSCs, the optimal number of RGs was four, while the two-RG combination producing the most similar results was TBP and YWHAZ. CONCLUSIONS: A common reference...

  6. Design, construction, and analysis of a continuous-temperature infrared calibrator for temperature measurement using an infrared scanner.

    Science.gov (United States)

    Hsieh, C K; Su, K C

    1979-07-01

    A continuous-temperature infrared calibrator is designed and constructed for providing reference video signals in temperature measurement using an infrared scanner. The calibrator can be controlled for a wide range of temperature settings and to present a continuous span of reference signals for calibration purposes. Both analytical and experimental methods are used to evaluate the performance of the calibrator. Results show that the calibrator has a normal total emissivity of at least 0.984, which is about 1% lower than the predicted value. Methods to improve the emissivity of the calibrator are also discussed. The paper provides for analytical equations useful for parameters estimation in the future design of the calibrator.

  7. Error Self-calibration Method in Spatial Spectrum Estimation

    Directory of Open Access Journals (Sweden)

    Huang Chuan-lu

    2014-10-01

    Full Text Available An important bottleneck in spatial spectrum estimation theory is array errors. A new error self-calibration method is presented on the basis of active error calibration and online self-calibration theories. An algorithm combining Direction Of Arrival (DOA estimation and array complex gain error calibration is developed using an auxiliary source without accurate spatial location information and numerical optimization calculation; the error calibration parameters can be used in the following spatial spectrum estimation. The method has a higher veracity than the active correction algorithm and is an offline calculation procedure, having the advantage of small computation amount, similar to the online self-calibration method, and avoiding accurate spatial location information in classical active calibration method.

  8. LLNL Calibration Program: Data Collection, Ground Truth Validation, and Regional Coda Magnitude

    Energy Technology Data Exchange (ETDEWEB)

    Myers, S C; Mayeda, K; Walter, C; Schultz, C; O' Boyle, J; Hofstetter, A; Rodgers, A; Ruppert, S

    2001-08-28

    Lawrence Livermore National Laboratory (LLNL) integrates and collects data for use in calibration of seismic detection, location, and identification. Calibration data is collected by (1) numerous seismic field efforts, many conducted under NNSA (ROA) and DTRA (PRDA) contracts, and (2) permanent seismic stations that are operated by national and international organizations. Local-network operators and international organizations (e.g. International Seismic Center) provide location and other source characterization (collectively referred to as source parameters) to LLNL, or LLNL determines these parameters from raw data. For each seismic event, LLNL rigorously characterizes the uncertainty of source parameters. This validation process is used to identify events whose source parameters are accurate enough for use in calibration. LLNL has developed criteria for determining the accuracy of seismic locations and methods to characterize the covariance of calibration datasets. Although the most desirable calibration events are chemical and nuclear explosions with highly accurate locations and origin times, catalogues of naturally occurring earthquakes offer needed geographic coverage that is not provided by man made sources. The issue in using seismically determined locations for calibration is validating the location accuracy. Sweeney (1998) presented a 50/90 teleseismic, network-coverage criterion (50 defining phases and 90{sup o} maximum azimuthal gap) that generally results in 15-km maximum epicenter error. We have also conducted tests of recently proposed local/regional criteria and found that 10-km accuracy can be achieved by applying a 20/90 criteria. We continue to conduct tests that may validate less stringent criteria (which will produce more calibration events) while maintaining desirable location accuracy. Lastly, we examine methods of characterizing the covariance structure of calibration datasets. Each dataset is likely to be effected by distinct error

  9. CRYOGENIC SYSTEM FOR PRECISE CALIBRATION OF TEMPERATURE SENSORS

    Directory of Open Access Journals (Sweden)

    A. N. Solovyev

    2016-09-01

    Full Text Available A calibration technique for cryogenic temperature sensors is proposed and implemented. The experimental setup is based on the helium cryogenerator, providing calibration of the temperature sensors of various types in wide temperature range, including cryogenic band (25-100K. A condensation thermometer with hydrogen, neon, argon and xenon as working gases is used as a reference sensor. The experimental setup was successfully used for precise (0.1K precision calibration of platinum resistive temperature detectors (Pt-100 for international nuclear physics experiments MuSun and PolFusion. The setup can also be used for calibration of temperature sensors of the other types.

  10. Aquarius L-Band Radiometers Calibration Using Cold Sky Observations

    Science.gov (United States)

    Dinnat, Emmanuel P.; Le Vine, David M.; Piepmeier, Jeffrey R.; Brown, Shannon T.; Hong, Liang

    2015-01-01

    An important element in the calibration plan for the Aquarius radiometers is to look at the cold sky. This involves rotating the satellite 180 degrees from its nominal Earth viewing configuration to point the main beams at the celestial sky. At L-band, the cold sky provides a stable, well-characterized scene to be used as a calibration reference. This paper describes the cold sky calibration for Aquarius and how it is used as part of the absolute calibration. Cold sky observations helped establish the radiometer bias, by correcting for an error in the spillover lobe of the antenna pattern, and monitor the long-term radiometer drift.

  11. Beyond Californium-A Neutron Generator Alternative for Dosimetry and Instrument Calibration in the U.S.

    Science.gov (United States)

    Piper, Roman K; Mozhayev, Andrey V; Murphy, Mark K; Thompson, Alan K

    2017-09-01

    Evaluations of neutron survey instruments, area monitors, and personal dosimeters rely on reference neutron radiations, which have evolved from the heavy reliance on (α,n) sources to a shared reliance on (α,n) and the spontaneous fission neutrons of californium-252 (Cf). Capable of producing high dose equivalent rates from an almost point source geometry, the characteristics of Cf are generally more favorable when compared to the use of (α,n) and (γ,n) sources or reactor-produced reference neutron radiations. Californium-252 is typically used in two standardized configurations: unmoderated, to yield a fission energy spectrum; or with the capsule placed within a heavy-water moderating sphere to produce a softened spectrum that is generally considered more appropriate for evaluating devices used in nuclear power plant work environments. The U.S. Department of Energy Cf Loan/Lease Program, a longtime origin of affordable Cf sources for research, testing and calibration, was terminated in 2009. Since then, high-activity sources have become increasingly cost-prohibitive for laboratories that formerly benefited from that program. Neutron generators, based on the D-T and D-D fusion reactions, have become economically competitive with Cf and are recognized internationally as important calibration and test standards. Researchers from the National Institute of Standards and Technology and the Pacific Northwest National Laboratory are jointly considering the practicality and technical challenges of implementing neutron generators as calibration standards in the U.S. This article reviews the characteristics of isotope-based neutron sources, possible isotope alternatives to Cf, and the rationale behind the increasing favor of electronically generated neutron options. The evaluation of a D-T system at PNNL has revealed characteristics that must be considered in adapting generators to the task of calibration and testing where accurate determination of a dosimetric quantity is

  12. 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....

  13. 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...

  14. 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...

  15. 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.

  16. Ames Balance Calibration Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Operations at the lab include calibrating balances for the Ames Wind Tunnels as well as for approved outside projects. Ames has a large inventory of TASK multi-piece...

  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. Standard guide for establishing calibration for a measurement method used to analyze nuclear fuel cycle materials

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This guide provides the basis for establishing calibration for a measurement method typically used in an analytical chemistry laboratory analyzing nuclear materials. Guidance is included for such activities as preparing a calibration procedure, selecting a calibration standard, controlling calibrated equipment, and documenting calibration. The guide is generic and any required technical information specific for a given method must be obtained from other sources.

  19. 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...

  20. The East Siberian Arctic Shelf is a significant source of atmospheric methane as referred from multi-year ship-based observations (2000-2015)

    Science.gov (United States)

    Kosmach, D.; Semiletov, I. P.; Shakhova, N. E.; Salyuk, A.

    2015-12-01

    According to NOAA/CMDL data, the highest concentration and greatest seasonal amplitudes of atmospheric methane (CH4) occur at 60-70N, outside the 30-60N band where the main sources of anthropogenic CH4 is located, indicating that the northern environment is a source of these gases. Analyses of ice core samples also suggest a strong pole-to-pole gradient existing during inter-glacial epochs back to preindustrial times, which is independent of anthropogenic activity. The global budget of CH4 established >40 years ago, when very little knowledge existed about Arctic terrestrial sources and nothing was known about Arctic marine sources, has never considered contribution of Arctic sources of CH4 adequately. Here we present results of the multiyear high-precision continuous measurements across the Barents Sea, the Kara Sea, the Laptev Sea, the East Siberian Sea, the Chukchi Sea, the Bering Sea, the Sea of Okhotsk and the Japan Sea performed during one expedition in each of two years (2011 and 2012). Results of our investigations demonstrate that concentrations of dissolved CH4 measured in the surface water in all 8 seas were supersaturated regards to the atmosphere. However, anomalously high concentrations of dissolved CH4 in the surface water (up to 5,000-12,000% of super-saturation) was found in the East Siberian Arctic Shelf, which is composed of the Laptev Sea, the East Siberian Sea and the Chukchi Sea.

  1. Progress in Using Continuum radiation for AXAF Calibration

    Science.gov (United States)

    Kolodziejczak, J. J.; Austin, R. A.; Elsner, R. F.; O'Dell, S. L.; Sulkanen, M. E.; Swartz, D. A.; Tennant, A. F.; Weisskopf, M. C.; Zirnstein, G.; McDermott, W. C.; hide

    1998-01-01

    X-ray calibration of the AXAF observatory at MSFC's X-Ray Calibration Facility (XRCF) made novel use of the x-ray continuum from a conventional electron-impact source. Taking advantage of the good spectral resolution of solid-state detectors, continuum measurements proved advantageous in calibrating the effective area of AXAF's High-Resolution Mirror Assembly (HRMA) and in verifying its alignment to the XRCF's optical axis. Further verification of AXAF response models will be presented.

  2. Uses of continuum radiation in the AXAF calibration

    Science.gov (United States)

    Kolodziejczak, J. J.; Austin, R. A.; Elsner, R. F.; O'Dell, S. L.; Sulkanen, M. E.; Swartz, D. A.; Tennant, A. F.; Weisskopf, M. C.; Zirnstein, G.; McDermott, W. C.

    1997-01-01

    X-ray calibration of the Advanced X-ray Astrophysics Facility (AXAF) observatory at the MSFC X-Ray Calibration Facility (XRCF) made novel use of the x-ray continuum from a conventional electron-impact source. Taking advantage of the good spectral resolution of solid-state detectors, continuum measurements proved advantageous in calibrating the effective area of AXAF's High-Resolution Mirror Assembly (HRMA) and in verifying its alignment to the XRCF's optical axis.

  3. Lidar to lidar calibration of Ground-based Lidar

    DEFF Research Database (Denmark)

    Fernandez Garcia, Sergio; Courtney, Michael

    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....

  4. Application of the Monte Carlo method to the analysis of measurement geometries for the calibration of a HP Ge detector in an environmental radioactivity laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Rodenas, Jose [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Apartado 22012, E-46071 Valencia (Spain)], E-mail: jrodenas@iqn.upv.es; Gallardo, Sergio; Ballester, Silvia; Primault, Virginie [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Apartado 22012, E-46071 Valencia (Spain); Ortiz, Josefina [Laboratorio de Radiactividad Ambiental, Universidad Politecnica de Valencia, Apartado 22012, E-46071 Valencia (Spain)

    2007-10-15

    A gamma spectrometer including an HP Ge detector is commonly used for environmental radioactivity measurements. The efficiency of the detector should be calibrated for each geometry considered. Simulation of the calibration procedure with a validated computer program is an important auxiliary tool for environmental radioactivity laboratories. The MCNP code based on the Monte Carlo method has been applied to simulate the detection process in order to obtain spectrum peaks and determine the efficiency curve for each modelled geometry. The source used for measurements was a calibration mixed radionuclide gamma reference solution, covering a wide energy range (50-2000 keV). Two measurement geometries - Marinelli beaker and Petri boxes - as well as different materials - water, charcoal, sand - containing the source have been considered. Results obtained from the Monte Carlo model have been compared with experimental measurements in the laboratory in order to validate the model.

  5. Calibrating spectral images using penalized likelihood

    NARCIS (Netherlands)

    Heijden, van der G.W.A.M.; Glasbey, C.

    2003-01-01

    A new method is presented for automatic correction of distortions and for spectral calibration (which band corresponds to which wavelength) of spectral images recorded by means of a spectrograph. The method consists of recording a bar-like pattern with an illumination source with spectral bands

  6. A gyroscope calibration analysis for the Gamma Ray Observatory (GRO)

    Science.gov (United States)

    Ketchum, Eleanor A.; Lee, Michael H.

    1989-01-01

    Current documentation and software do not adequately address the calculation and use of the optimal weight matrices involved in calibrating inertial reference units (IRU). Several facets of the GRO IRU calibration as it relates to the bias and misalignment weighting matrices are investigated. The physical meaning and use of the bias and misalignment weight matrices in IRU calibration are examined. The relation of the weighting and the final biases, misalignments, and their corrections are pursued. Methods for determining reliable, realistic weighting matrices to be used in the GRO IRU calibration (IRUCAL) utility are determined. Possible correlations among observation uncertainties are also explored. For the undetermined case where the maneuvers are insufficient to identify all calibration parameters, the weighting matrices allow as much information as possible to be extracted from the measurements. Finally, applicable simulated flight data are used, incorporating the appropriate calibration maneuvers, to test the weighting matrices in the IRUCAL utility, and examine correlation effects.

  7. A survey of the optical hazards associated with hospital light sources with reference to the Control of Artificial Optical Radiation at Work Regulations 2010.

    Science.gov (United States)

    Coleman, A; Fedele, F; Khazova, M; Freeman, P; Sarkany, R

    2010-09-01

    Workplace exposure to coherent and incoherent optical radiation from artificial sources is regulated under the Artificial Optical Radiation Directive (AORD) 2006/25/EC, now implemented in the UK under the Control of Artificial Optical Radiation at Work Regulations (AOR) 2010. These regulations set out exposure limit values. Implementing the AOR (2010 Health and Safety Statutory Instrument No 1140 www.legislation.gov.uk/uksi/2010/1140/pdf/uksi_20101140_en.pdf) requirements in a hospital environment is a potentially complex problem because of the wide variety of sources used for illumination, diagnosis and therapy. A survey of sources of incoherent optical radiation in a large hospital is reported here. The survey covers examples of office lighting, operating theatre lighting, examination lamps, and sources for ultraviolet phototherapy and visible phototherapies, including photodynamic therapy and neonatal blue-light therapy. The results of the survey are used to inform consideration of the strategy that a hospital might reasonably adopt both to demonstrate compliance with the AOR (2010) and to direct implementation effort.

  8. A survey of the optical hazards associated with hospital light sources with reference to the Control of Artificial Optical Radiation at Work Regulations 2010

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, A; Fedele, F; Freeman, P [Medical Physics Department, Guy' s and St Thomas' NHS Foundation Trust, Westminster Bridge Road, London SE1 7EH (United Kingdom); Khazova, M [Health Protection Agency, Centre for Radiation, Chemical and Environmental Hazards, Radiation Protection Division, Chilton, Didcot, Oxfordshire OX11 ORQ (United Kingdom); Sarkany, R, E-mail: andrew.coleman@gstt.nhs.u [St John' s Institute of Dermatology, Guy' s and St Thomas' NHS Foundation Trust, Westminster Bridge Road, London SE1 7EH (United Kingdom)

    2010-09-15

    Workplace exposure to coherent and incoherent optical radiation from artificial sources is regulated under the Artificial Optical Radiation Directive (AORD) 2006/25/EC, now implemented in the UK under the Control of Artificial Optical Radiation at Work Regulations (AOR) 2010. These regulations set out exposure limit values. Implementing the AOR (2010 Health and Safety Statutory Instrument No 1140 www.legislation.gov.uk/uksi/2010/1140/pdf/uksi{sub 2}0101140{sub e}n.pdf) requirements in a hospital environment is a potentially complex problem because of the wide variety of sources used for illumination, diagnosis and therapy. A survey of sources of incoherent optical radiation in a large hospital is reported here. The survey covers examples of office lighting, operating theatre lighting, examination lamps, and sources for ultraviolet phototherapy and visible phototherapies, including photodynamic therapy and neonatal blue-light therapy. The results of the survey are used to inform consideration of the strategy that a hospital might reasonably adopt both to demonstrate compliance with the AOR (2010) and to direct implementation effort.

  9. 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.

  10. R quick syntax reference

    CERN Document Server

    Tollefson, Margot

    2014-01-01

    The R Quick Syntax Reference is a handy reference book detailing the intricacies of the R language. Not only is R a free, open-source tool, R is powerful, flexible, and has state of the art statistical techniques available. With the many details which must be correct when using any language, however, the R Quick Syntax Reference makes using R easier.Starting with the basic structure of R, the book takes you on a journey through the terminology used in R and the syntax required to make R work. You will find looking up the correct form for an expression quick and easy. With a copy of the R Quick

  11. Handbook of reference electrodes

    CERN Document Server

    Inzelt, György; Scholz, Fritz

    2013-01-01

    Reference Electrodes are a crucial part of any electrochemical system, yet an up-to-date and comprehensive handbook is long overdue. Here, an experienced team of electrochemists provides an in-depth source of information and data for the proper choice and construction of reference electrodes. This includes all kinds of applications such as aqueous and non-aqueous solutions, ionic liquids, glass melts, solid electrolyte systems, and membrane electrodes. Advanced technologies such as miniaturized, conducting-polymer-based, screen-printed or disposable reference electrodes are also covered. Essen

  12. Online Calibration Methods for the DINA Model with Independent Attributes in CD-CAT

    Science.gov (United States)

    Chen, Ping; Xin, Tao; Wang, Chun; Chang, Hua-Hua

    2012-01-01

    Item replenishing is essential for item bank maintenance in cognitive diagnostic computerized adaptive testing (CD-CAT). In regular CAT, online calibration is commonly used to calibrate the new items continuously. However, until now no reference has publicly become available about online calibration for CD-CAT. Thus, this study investigates the…

  13. A force plate based method for the calibration of force/torque sensors

    NARCIS (Netherlands)

    Faber, Gert S.; Chang, Chien-Chi; Kingma, Idsart; Schepers, H. Martin; Herber, S.; Veltink, Petrus H.; Dennerlein, Jack T.

    2012-01-01

    This study describes a novel calibration method for six-degrees-of-freedom force/torque sensors (FTsensors) using a pre-calibrated force plate (FP) as a reference measuring device. In this calibration method, the FTsensor is rigidly connected to a FP and force/torque data are synchronously recorded

  14. Freehand ultrasound calibration: phantom versus tracked pointer

    Science.gov (United States)

    Welch, Mattea; Andrea, Jennifer; Ungi, Tamas; Fichtinger, Gabor

    2013-03-01

    PURPOSE: Ultrasound-guided tracked navigation requires spatial calibration between the ultrasound beam and the tracker. We examined the reproducibility and accuracy of two popular open source calibration methods1 with a handheld linear ultrasound transducer. METHODS: A total of 10 calibrations were performed using (1) a double N-wire phantom with automatic image segmentation and registration; (2) and registration of landmark points collected with a tracked pointer. Reproducibility and accuracy were characterized by comparing the resulting transformation matrices, and by comparing ground truth landmark points. RESULTS: Transformation matrices calculated with an N-wire phantom showed a variance of X: 0.02 mm (in the direction of sound propagation), Y: 0.03 mm (in the direction of transducer elements) and Z: 0.21 mm (in the elevation direction). Transformation matrices obtained with tracked pointer showed a variance of X: 0.1 mm, Y: 0.10 mm and Z: 0.43 mm. Calibration accuracy was tested with ground truth cross wire points. The N-wire phantom provided a calibration with a distance from ground truth of X: 2.44 +/- 1.44 mm, Y: 1.21 +/- 0.88 mm, and Z: 1.12 +/- 0.82 mm. Tracked pointer calibration had a distance from the ground truth of X: 0.23 +/- 0.16 mm, Y: 0.62 +/- 0.31 mm, and Z: 0.45 +/- 0.33 mm. Distance from ground truth was significantly less (ptracked pointer method in all directions. CONCLUSION: Calibration using a tracked pointer had a slightly greater variance; however it showed better accuracy over calibrations calculated with N-wire phantoms.

  15. Calibration of neutron detectors on the Joint European Torus

    Science.gov (United States)

    Batistoni, Paola; Popovichev, S.; Conroy, S.; Lengar, I.; Čufar, A.; Abhangi, M.; Snoj, L.; Horton, L.; JET Contributors

    2017-10-01

    The present paper describes the findings of the calibration of the neutron yield monitors on the Joint European Torus (JET) performed in 2013 using a 252Cf source deployed inside the torus by the remote handling system, with particular regard to the calibration of fission chambers which provide the time resolved neutron yield from JET plasmas. The experimental data obtained in toroidal, radial, and vertical scans are presented. These data are first analysed following an analytical approach adopted in the previous neutron calibrations at JET. In this way, a calibration function for the volumetric plasma source is derived which allows us to understand the importance of the different plasma regions and of different spatial profiles of neutron emissivity on fission chamber response. Neutronics analyses have also been performed to calculate the correction factors needed to derive the plasma calibration factors taking into account the different energy spectrum and angular emission distribution of the calibrating (point) 252Cf source, the discrete positions compared to the plasma volumetric source, and the calibration circumstances. All correction factors are presented and discussed. We discuss also the lessons learnt which are the basis for the on-going 14 MeV neutron calibration at JET and for ITER.

  16. Near-Infrared Camera Calibration for Optical Surgical Navigation.

    Science.gov (United States)

    Cai, Ken; Yang, Rongqian; Lin, Qinyong; Liu, Sujuan; Chen, Huazhou; Ou, Shanxing; Huang, Wenhua; Zhou, Jing

    2016-03-01

    Near-infrared optical tracking devices, which are important components of surgical navigation systems, need to be calibrated for effective tracking. The calibration results has a direct influence on the tracking accuracy of an entire system. Therefore, the study of calibration techniques is of theoretical significance and practical value. In the present work, a systematic calibration method based on movable plates is established, which analyzes existing calibration theories and implements methods using calibration reference objects. First, the distortion model of near-infrared cameras (NICs) is analyzed in the implementation of this method. Second, the calibration images from different positions and orientations are used to establish the required linear equations. The initial values of the NIC parameters are calculated with the direct linear transformation method. Finally, the accurate internal and external parameters of the NICs are obtained by conducting nonlinear optimization. Analysis results show that the relative errors of the left and right NICs in the tracking system are 0.244 and 0.282 % for the focal lengths and 0.735 and 1.111 % for the principal points, respectively. The image residuals of the left and right image sets are both less than 0.01 pixel. The standard error of the calibration result is lower than 1, and the measurement error of the tracking system is less than 0.3 mm. The experimental data show that the proposed method of calibrating NICs is effective and can generate favorable calibration results.

  17. Calibration Under Uncertainty.

    Energy Technology Data Exchange (ETDEWEB)

    Swiler, Laura Painton; Trucano, Timothy Guy

    2005-03-01

    This report is a white paper summarizing the literature and different approaches to the problem of calibrating computer model parameters in the face of model uncertainty. Model calibration is often formulated as finding the parameters that minimize the squared difference between the model-computed data (the predicted data) and the actual experimental data. This approach does not allow for explicit treatment of uncertainty or error in the model itself: the model is considered the %22true%22 deterministic representation of reality. While this approach does have utility, it is far from an accurate mathematical treatment of the true model calibration problem in which both the computed data and experimental data have error bars. This year, we examined methods to perform calibration accounting for the error in both the computer model and the data, as well as improving our understanding of its meaning for model predictability. We call this approach Calibration under Uncertainty (CUU). This talk presents our current thinking on CUU. We outline some current approaches in the literature, and discuss the Bayesian approach to CUU in detail.

  18. A spectrally tunable solid-state source for radiometric, photometric, and colorimetric applications

    Science.gov (United States)

    Fryc, Irena; Brown, Steven W.; Eppeldauer, George P.; Ohno, Yoshihiro

    2004-10-01

    A spectrally tunable light source using a large number of LEDs and an integrating sphere has been designed and being developed at NIST. The source is designed to have a capability of producing any spectral distributions mimicking various light sources in the visible region by feedback control of individual LEDs. The output spectral irradiance or radiance of the source will be calibrated by a reference instrument, and the source will be used as a spectroradiometric as well as photometric and colorimetric standard. The use of the tunable source mimicking spectra of display colors, for example, rather than a traditional incandescent standard lamp for calibration of colorimeters, can reduce the spectral mismatch errors of the colorimeter measuring displays significantly. A series of simulations have been conducted to predict the performance of the designed tunable source when used for calibration of colorimeters. The results indicate that the errors can be reduced by an order of magnitude compared with those when the colorimeters are calibrated against Illuminant A. Stray light errors of a spectroradiometer can also be effectively reduced by using the tunable source producing a blackbody spectrum at higher temperature (e.g., 9000 K). The source can also approximate various CIE daylight illuminants and common lamp spectral distributions for other photometric and colorimetric applications.

  19. First experience with single-source dual-energy computed tomography in six patients with acute arthralgia: a feasibility experiment using joint aspiration as a reference

    Energy Technology Data Exchange (ETDEWEB)

    Diekhoff, Torsten; Kiefer, Tobias; Hamm, Bernd; Hermann, Kay-Geert A. [Charite - Universitaetsmedizin Berlin Campus Mitte, Humboldt-Universitaet zu Berlin, Freie Universitaet Berlin, Department of Radiology, Berlin (Germany); Ziegeler, Katharina; Feist, Eugen [Charite - Universitaetsmedizin Berlin Campus Mitte, Humboldt-Universitaet zu Berlin, Freie Universitaet Berlin, Department of Rheumatology and Clinical Immunology, Berlin (Germany); Mews, Juergen [Toshiba Medical Systems Europe, BV, Zoetermeer (Netherlands)

    2015-11-15

    Dual-energy computed tomography (DECT) is an emerging imaging technique for examining patients with suspected gout. Single-source dual-energy CT (S-DECT) is a new way of obtaining DECT information on conventional CT scanners rather than using special dual-source CT systems. We tested the feasibility of S-DECT (320-row CT; Aquilion ONE, Toshiba Medical Systems, Otawara, Japan) in 6 patients (5 men, 1 woman; mean age 61.3, range 48 to 69 years) with acute arthralgia and suspected gout, and compared the S-DECT findings with the results of joint aspiration. Three patients had a diagnosis of gouty arthritis with negatively birefringent crystals in synovial fluid, in addition to gouty tophi in S-DECT. Three patients had no detectable crystals by polarization microscopy and no tophi on DECT. Their final diagnoses were rheumatoid arthritis, activated osteoarthritis, and septic arthritis in one case each. This initial experience suggests that S-DECT might be a valuable alternative to dual-source CT. Hence, more patients may benefit from its additional diagnostic abilities in the future. (orig.)

  20. SCIAMACHY Level 1 data: calibration concept and in-flight calibration

    Directory of Open Access Journals (Sweden)

    G. Lichtenberg

    2006-01-01

    Full Text Available The calibration of SCIAMACHY was thoroughly checked since the instrument was launched on-board ENVISAT in February 2002. While SCIAMACHY's functional performance is excellent since launch, a number of technical difficulties have appeared, that required adjustments to the calibration. The problems can be separated into three types: (1 Those caused by the instrument and/or platform environment. Among these are the high water content in the satellite structure and/or MLI layer. This results in the deposition of ice on the detectors in channels 7 and 8 which seriously affects the retrievals in the IR, mostly because of the continuous change of the slit function caused by scattering of the light through the ice layer. Additionally a light leak in channel 7 severely hampers any retrieval from this channel. (2 Problems due to errors in the on-ground calibration and/or data processing affecting for example the radiometric calibration. A new approach based on a mixture of on-ground and in-flight data is shortly described here. (3 Problems caused by principal limitations of the calibration concept, e.g. the possible appearance of spectral structures after the polarisation correction due to unavoidable errors in the determination of atmospheric polarisation. In this paper we give a complete overview of the calibration and problems that still have to be solved. We will also give an indication of the effect of calibration problems on retrievals where possible. Since the operational processing chain is currently being updated and no newly processed data are available at this point in time, for some calibration issues only a rough estimate of the effect on Level 2 products can be given. However, it is the intention of this paper to serve as a future reference for detailed studies into specific calibration issues.

  1. Resonance absorption measurements of atom concentrations in reacting gas mixtures. VI. Shapes of the vacuum ultraviolet oxygen (3S-3P) resonance triplet from microwave sources and empirical calibration in a shock tube

    Science.gov (United States)

    Pamidimukkala, Krishna M.; Lifshitz, Assa; Skinner, Gordon B.; Wood, David R.

    1981-08-01

    Spectral line profiles of the atomic oxygen triplet 3S1-3P2,1,0 emitted from microwave discharges in O2-He mixtures containing 0.1% O2 were measured in the 43rd order using a 2 m vacuum Czerny-Turner scanning spectrometer under three different lamp conditions. The profiles varied from nearly Gaussian to highly self-absorbed. The line shapes were accounted for by the amount of light absorbed by ground state oxygen atoms within the lamp. Experiments were carried out to calibrate the microwave discharge lamp for analysis of oxygen atoms using oxygen resonance triplet absorption. Known concentration of O atoms were produced in the temperature range 1950-2600 K in a shock tube by the complete dissociation of dilute (1-20 ppm) mixtures of N2O in Ar and related to the fraction of light absorbed. It was found that the ratios of the intensities of the oxygen components, measured using a low-resolution monochromator, can be used to obtain resonably accurate calibration curves. Kinetic data obtained on N2O dissociation as a part of our calibration experiments in the temperature range 1519-2408 K are also presented; the results are consistent with the correlations of Baulch et al. It was confirmed that O atom concentrations during calibration experiments were determined by stoichiometry, and not by the kinetics of N2O dissociation.

  2. Calibration method for a in vivo measurement system using mathematical simulation of the radiation source and the detector; Metodo de calibracao de um sistema de medida in vivo atraves da simulacao matematica da fonte de radiacao e do detector

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, John

    1998-12-31

    A Monte Carlo program which uses a voxel phantom has been developed to simulate in vivo measurement systems for calibration purposes. The calibration method presented here employs a mathematical phantom, produced in the form of volume elements (voxels), obtained through Magnetic Resonance Images of the human body. The calibration method uses the Monte Carlo technique to simulate the tissue contamination, the transport of the photons through the tissues and the detection of the radiation. The program simulates the transport and detection of photons between 0.035 and 2 MeV and uses, for the body representation, a voxel phantom with a format of 871 slices each of 277 x 148 picture elements. The Monte Carlo code was applied to the calibration of in vivo systems and to estimate differences in counting efficiencies between homogeneous and non-homogeneous radionuclide distributions in the lung. Calculations show a factor of 20 between deposition of {sup 241} Am at the back compared with the front of the lung. The program was also used to estimate the {sup 137} Cs body burden of an internally contaminated individual, counted with an 8 x 4 Nal (TI) detector and an {sup 241} Am body burden of an internally contaminated individual, who was counted using a planar germanium detector. (author) 24 refs., 38 figs., 23 tabs.

  3. WFIRST WFI Calibration Requirements

    Science.gov (United States)

    Scolnic, Daniel; Casertano, Stephano; WFIRST Calibration Group

    2018-01-01

    The Wide Field InfraRed Survey Telescope (WFIRST), with a planned launch in the mid-2020’s, will enable multiple generation-defining measurements in astrophysics and cosmology. One of the key goals of the mission is to limit calibration uncertainties in order to enable a wide range of experiments. Here we present the work of the WFIRST WFI Calibration Working Group, which has compiled a comprehensive set of calibration needs derived from the Mission science requirements, and has outlined a plan toachieve them. In many areas, the accuracy required has yet to be reached in any comparable mission or project. We present here the various plans of on-ground characterization, pre-launch data; internal measurements and observations in orbit; and external observations.

  4. 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...... 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 [2]. The possible measurement sector for power performance...... according to [1] is also described in [2] and no results from the site calibration have shown any necessary exclusion from this sector. All parts of the sensors and the measurement system have been installed by DTU....

  5. TARGETLESS CAMERA CALIBRATION

    Directory of Open Access Journals (Sweden)

    L. Barazzetti

    2012-09-01

    Full Text Available In photogrammetry a camera is considered calibrated if its interior orientation parameters are known. These encompass the principal distance, the principal point position and some Additional Parameters used to model possible systematic errors. The current state of the art for automated camera calibration relies on the use of coded targets to accurately determine the image correspondences. This paper presents a new methodology for the efficient and rigorous photogrammetric calibration of digital cameras which does not require any longer the use of targets. A set of images depicting a scene with a good texture are sufficient for the extraction of natural corresponding image points. These are automatically matched with feature-based approaches and robust estimation techniques. The successive photogrammetric bundle adjustment retrieves the unknown camera parameters and their theoretical accuracies. Examples, considerations and comparisons with real data and different case studies are illustrated to show the potentialities of the proposed methodology.

  6. Calibrating the Athena telescope

    Science.gov (United States)

    de Bruijne, J.; Guainazzi, M.; den Herder, J.; Bavdaz, M.; Burwitz, V.; Ferrando, P.; Lumb, D.; Natalucci, L.; Pajot, F.; Pareschi, G.

    2017-10-01

    Athena is ESA's upcoming X-ray mission, currently set for launch in 2028. With two nationally-funded, state-of-the-art instruments (a high-resolution spectrograph named X-IFU and a wide-field imager named WFI), and a telescope collecting area of 1.4-2 m^2 at 1 keV, the calibration of the spacecraft is a challenge in itself. This poster presents the current (spring 2017) plan of how to calibrate the Athena telescope. It is based on a hybrid approach, using bulk manufacturing and integration data as well as dedicated calibration measurements combined with a refined software model to simulate the full response of the optics.

  7. Accurate wavelength calibration method for compact CCD spectrometer.

    Science.gov (United States)

    Sun, Y C; Huang, C; Xia, G; Jin, S Q; Lu, H B

    2017-04-01

    Wavelength calibration is an important step in charge-coupled device (CCD) spectrometers. In this paper, an accurate calibration method is proposed. A model of a line profile spectrum is built at the beginning, followed by noise reduction, bandwidth correction, and automatic peak-seeking treatment. Experimental tests are conducted on the USB4000 spectrometer with a mercury-argon calibration light source. Compared with the traditional method, the results show that this wavelength calibration procedure obtains higher accuracy and the deviations are within 0.1 nm.

  8. AUTOMATIC CALIBRATION METHOD FOR STEREOSCOPIC SYSTEM

    Directory of Open Access Journals (Sweden)

    A. V. Krasnyaschikh

    2014-07-01

    Full Text Available The paper deals with a new method of automatic calibration for stereoscopic system using test object. The idea of the method is to register stereoscopic image of specially selected reference object in the form of a chessboard with an extra field – a frame around chessboard – by means of two cameras. An algorithm implementing this method consists of seven stages: registration of set of images for a test object; image threshold filtering; recognition of test object by size and shape; background removal; position determination of four edge points; calibrating of the first and the second cameras; calibrating of stereoscopic system on the whole. The calibration process for the first and the second cameras and the system is performed by using a program developed by Jean-Yves Bouguet. Mathematical and physical modeling is done by means of two measuring cameras and MATLAB software package. Comparative error study for determination of the coordinates of test points in manual and automatic mode is carried out by modeling, as well as calibration error depending on the number of images obtained by stereo pair.

  9. Low-level radioactive waste from commercial nuclear reactors. Volume 3. Bibliographic abstracts of significant source references. Part 2. Bibliography for treatment, storage, disposal and transportation regulatory constraints

    Energy Technology Data Exchange (ETDEWEB)

    Jolley, R.L.; Rodgers, B.R.

    1986-05-01

    The overall task of this program was to provide an assessment of currently available technology for treating commercial low-level radioactive waste (LLRW), to initiate development of a methodology for choosing one technology for a given application, and to identify research needed to improve current treatment techniques and decision methodology. The resulting report is issued in four volumes. Volume 3 of this series is a collection of abstracts of most of the reference documents used for this study. Because of the large volume of literature, the abstracts have been printed in two separate parts. Federal, state, and local regulations affect the decision process for selecting technology applications. Regulations may favor a particular technology and may prevent application of others. Volume 3, part 2 presents abstracts of the regulatory constraint documents that relate to all phases of LLRW management (e.g., treatment, packaging, storage, transportation, and disposal).

  10. Wavelength calibration of an imaging spectrometer based on Savart interferometer

    Science.gov (United States)

    Li, Qiwei; Zhang, Chunmin; Yan, Tingyu; Quan, Naicheng; Wei, Yutong; Tong, Cuncun

    2017-09-01

    The basic principle of Fourier-transform imaging spectrometer (FTIS) based on Savart interferometer is outlined. The un-identical distribution of the optical path difference which leads to the wavelength drift of each row of the interferogram is analyzed. Two typical methods for wavelength calibration of the presented system are described. The first method unifies different spectral intervals and maximum spectral frequencies of each row by a reference monochromatic light with known wavelength, and the dispersion compensation of Savart interferometer is also involved. The second approach is based on the least square fitting which builds the functional relation between recovered wavelength, row number and calibrated wavelength by concise equations. The effectiveness of the two methods is experimentally demonstrated with monochromatic lights and mixed light source across the detecting band of the system, and the results indicate that the first method has higher precision and the mean root-mean-square error of the recovered wavelengths is significantly reduced from 19.896 nm to 1.353 nm, while the second method is more convenient to implement and also has good precision of 2.709 nm.

  11. SMAP RADAR Calibration and Validation

    Science.gov (United States)

    West, R. D.; Jaruwatanadilok, S.; Chaubel, J.

    2014-12-01

    The Soil Moisture Active Passive (SMAP) mission is planned to launch on Jan 8, 2015. The mission employs L-band radar and radiometer measurements to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Immediately following launch, there will be a 3 month instrument checkout period, followed by 6 months of level 1 (L1) calibration and validation. In this presentation, we will discuss the plans and preparations for the calibration and validation of L1 radar data from SMAP. At the start of the L1 cal/val period, we will validate the operation of the instrument and of the ground processing using tools that look at readily identifiable surface features such as coast lines and corner reflectors. Geometric biases will be fit and removed. Radiometric cross-calibration with PALSAR and Aquarius will also be performed using target regions in the Amazon rain forest selected for their stability and uniformity. As the L1 cal/val period progresses, the performance of the automated short and long term calibration modules in ground processing will be tracked and verified using data from stable reference targets such as the wind corrected ocean and selected areas of rain forest that have shown good temporal stability. The performance of the radio frequency interference (RFI) removal algorithm will be validated by processing data with the algorithm turned on and off, and using different parameter settings. Additional information on the extent of RFI will be obtained from a special RFI survey conducted early in the L1 cal/val period. Radar transmissions are turned off during the RFI survey, and receive only data are collected over a variety of operating frequencies. The model based Faraday rotation corrections will also be checked during the L1 cal/val by comparing the model Faraday rotation with the measured Faraday rotation obtained by the SMAP Radiometer. This work is supported by the SMAP project at the Jet

  12. Calibration of scanning Lidar

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Courtney, Michael

    This report describes the tests carried out on a scanning lidar at the DTU Test Station for large wind turbines, Høvsøre. The tests were divided in two parts. In the first part, the purpose was to obtain wind speed calibrations at two heights against two cup anemometers mounted on a mast. Additio......This report describes the tests carried out on a scanning lidar at the DTU Test Station for large wind turbines, Høvsøre. The tests were divided in two parts. In the first part, the purpose was to obtain wind speed calibrations at two heights against two cup anemometers mounted on a mast...

  13. Calibrated entanglement entropy

    Science.gov (United States)

    Bakhmatov, I.; Deger, N. S.; Gutowski, J.; Colgáin, E. Ó.; Yavartanoo, H.

    2017-07-01

    The Ryu-Takayanagi prescription reduces the problem of calculating entanglement entropy in CFTs to the determination of minimal surfaces in a dual anti-de Sitter geometry. For 3D gravity theories and BTZ black holes, we identify the minimal surfaces as special Lagrangian cycles calibrated by the real part of the holomorphic one-form of a spacelike hypersurface. We show that (generalised) calibrations provide a unified way to determine holographic entanglement entropy from minimal surfaces, which is applicable to warped AdS3 geometries. We briefly discuss generalisations to higher dimensions.

  14. Calibration with Absolute Shrinkage

    DEFF Research Database (Denmark)

    Øjelund, Henrik; Madsen, Henrik; Thyregod, Poul

    2001-01-01

    is suggested to cope with the singular design matrix most often seen in chemometric calibration. Furthermore, the proposed algorithm may be generalized to all convex norms like Sigma/beta (j)/(gamma) where gamma greater than or equal to 1, i.e. a method that continuously varies from ridge regression...... 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...

  15. Absolute calibration of a multilayer-based XUV diagnostic

    CERN Document Server

    Stuik, R; Tümmler, J; Bijkerk, F

    2002-01-01

    A portable, universal narrowband XUV diagnostic suitable for calibration of various XUV light sources, was built, tested and fully calibrated. The diagnostic allows measurement of the absolute XUV energy and average power in two selected wavelength bands, at 11.4 and 13.4 nm. In addition, the pulse-to-pulse and long-term XUV stability of the source can be assessed, as well as the contamination of multilayer XUV optics exposed to the source. This paper describes the full calibration procedure: all optical elements were calibrated at the wavelength of operation by Physikalisch-Technische Bundesanstalt at the storage ring Bessy II, a full analysis of geometrical factors was done, and the influence of the spectral emissivity of the source on the calibration was analyzed in detail. The calibration was performed both for the centroid wavelength as for the full bandwidth of the diagnostic. The total uncertainty in the absolute calibration allowed measurement of source characteristics with an uncertainty of less than...

  16. A method to enhance the measurement accuracy of Raman shift based on high precision calibration technique

    Science.gov (United States)

    Ding, Xiang; Li, Fei; Zhang, Jiyan; Liu, Wenli

    2016-10-01

    Raman spectrometers are usually calibrated periodically to ensure their measurement accuracy of Raman shift. A combination of a piece of monocrystalline silicon chip and a low pressure discharge lamp is proposed as a candidate for the reference standard of Raman shift. A high precision calibration technique is developed to accurately determine the standard value of the silicon's Raman shift around 520cm-1. The technique is described and illustrated by measuring a piece of silicon chip against three atomic spectral lines of a neon lamp. A commercial Raman spectrometer is employed and its error characteristics of Raman shift are investigated. Error sources are evaluated based on theoretical analysis and experiments, including the sample factor, the instrumental factor, the laser factor and random factors. Experimental results show that the expanded uncertainty of the silicon's Raman shift around 520cm-1 can acheive 0.3 cm-1 (k=2), which is more accurate than most of currently used reference materials. The results are validated by comparison measurement between three Raman spectrometers. It is proved that the technique can remarkably enhance the accuracy of Raman shift, making it possible to use the silicon and the lamp to calibrate Raman spectrometers.

  17. Multimodal Spatial Calibration for Accurately Registering EEG Sensor Positions

    Directory of Open Access Journals (Sweden)

    Jianhua Zhang

    2014-01-01

    Full Text Available This paper proposes a fast and accurate calibration method to calibrate multiple multimodal sensors using a novel photogrammetry system for fast localization of EEG sensors. The EEG sensors are placed on human head and multimodal sensors are installed around the head to simultaneously obtain all EEG sensor positions. A multiple views’ calibration process is implemented to obtain the transformations of multiple views. We first develop an efficient local repair algorithm to improve the depth map, and then a special calibration body is designed. Based on them, accurate and robust calibration results can be achieved. We evaluate the proposed method by corners of a chessboard calibration plate. Experimental results demonstrate that the proposed method can achieve good performance, which can be further applied to EEG source localization applications on human brain.

  18. (Depth-dose curves of the beta reference fields (147)Pm, (85)Kr and (90)Sr/(90)Y produced by the beta secondary standard BSS2.

    Science.gov (United States)

    Brunzendorf, Jens

    2012-08-01

    The most common reference fields in beta dosimetry are the ISO 6980 series 1 radiation fields produced by the beta secondary standard BSS2 and its predecessor BSS. These reference fields require sealed beta radiation sources ((147)Pm, (85)Kr or (90)Sr/(90)Y) in combination with a source-specific beam-flattening filter, and are defined only at a given distance from the source. Every radiation sources shipped with the BSS2 is sold with a calibration certificate of the Physikalisch-Technische Bundesanstalt. The calibration workflow also comprises regular depth-dose measurements. This work publishes complete depth-dose curves of the series 1 sources (147)Pm, (85)Kr and (90)Sr/(90)Y in ICRU tissue up to a depth of 11 mm,when all electrons are stopped. For this purpose, the individual depth-dose curves of all BSS2 sources calibrated so far have been determined, i.e. the complete datasets of all BSS2 beta sources have been re-evaluated. It includes 191 depth-dose curves of 116 different sources comprising more than 2200 data points in total. Appropriate analytical representations of the nuclide-specific depth-dose curves are provided for the first time.

  19. In situ calibration of the sound strength parameter G.

    Science.gov (United States)

    Katz, Brian F G

    2015-08-01

    The room acoustic parameter "strength of sound G" is a measure of room amplification relative to a 10 m free-field reference. Due to this reference requirement, G is often considered excessively difficult to measure. Standards require reference measurements using reverberation or anechoic chambers. While possible for well-equipped laboratories, this is impractical for most practitioners. Considering the entire measurement chain, stability of amplifier and converter gains must be identical between on-site and calibration measurements, which cannot always be assured. An in situ calibration method is proposed, taking advantage of the full hall dataset. Results show significant advantages compared to previous methods.

  20. Traceability of solar UV measurements using the Qasume reference spectroradiometer.

    Science.gov (United States)

    Hülsen, Gregor; Gröbner, Julian; Nevas, Saulius; Sperfeld, Peter; Egli, Luca; Porrovecchio, Geiland; Smid, Marek

    2016-09-10

    One major objective of the European Joint Research Project "Traceability for surface spectral solar ultraviolet (UV) radiation" was to reduce the uncertainty of spectral UV measurements. The measurement instrument used for this work was the portable UV European reference spectroradiometer Qasume. The calibration uncertainty of this instrument was decreased and validated by a comparison of direct calibrations against a primary standard for spectral irradiance, a high temperature blackbody radiator, and against a reference detector using a spectrally tunable laser as a monochromatic source. The spectral irradiance responsivity of the reference detector is traceable to the primary standard of optical power, realized through a cryogenic radiometer, and to the SI unit of meter. The measuring technique was improved by the construction of a new reference spectroradiometer, QasumeII. An improved input optics removes the dependences of the measured solar irradiance on the angle of incident for solar zenith angle smaller than 75 deg. Moreover, a hybrid photon detection system enables continuous tracking of the instrument's responsivity changes. For both spectroradiometer systems an uncertainty budget was calculated. The improvements have reduced the measurement uncertainties of solar spectral UV irradiance measurements from 4.8% in 2005 to 2.0% (k=2) in the spectral region above 310 nm. The largest sources of uncertainty were the absolute spectral irradiance responsivity calibration, the angular response uncertainty, and the instrument stability using the hybrid detector, which were reduced from 3.6% to 1.1%, from 1.2% to 0.6%, and from 0.65% to 0.4%, with respect to the situation prior to the project. The new instrument was validated during a four month intercomparison relative to the Qasume reference. The mean ratio of the solar irradiance scans between the two reference spectroradiometers has an offset of +0.7% and a standard deviation of ±1.5% for a wavelength greater

  1. THz spectrometer calibration at FELIX

    Energy Technology Data Exchange (ETDEWEB)

    Koevener, Toke; Wunderlich, Steffen; Peier, Peter; Hass, Eugen; Schmidt, Bernhard [Deutsches Elektronen-Synchrotron, Hamburg (Germany)

    2016-07-01

    Coherent radiation spectroscopy is a suitable method for longitudinal electron bunch diagnostics at femtosecond bunch lengths. The absolute value of the longitudinal form factor, that is connected to the longitudinal profile, can be retrieved by measuring the intensity spectrum of a coherent transition radiation source at FLASH. The response function of the used spectrometer has to be well known in absolute values in order to perform accurate measurements. Until now, the response was predicted by calculations. As the free-electron lasers at the FELIX facility in Nijmegen (NL) provide quasi-monochromatic beams that can be tuned in a wide spectral range at micrometer wavelengths, a calibration campaign for two THz spectrometers was performed at this facility with the goal to deduce their response function. Here we present the setup at FELIX that was used for the calibration scans, the achieved scan ranges and the collected data. Furthermore, the analysis of the measured data is discussed. The results are then compared to the previous calculations of the response functions.

  2. LED-based spectrally tunable source for radiometric, photometric, and colorimetric applications

    Science.gov (United States)

    Fryc, Irena; Brown, Steven W.; Eppeldauer, George P.; Ohno, Yoshihiro

    2005-11-01

    A spectrally tunable light source using a large number of LEDs and an integrating sphere has been designed and is being constructed at the National Institute of Standards and Technology. The source is designed to have a capability of producing any spectral distribution, mimicking various light sources in the visible region by feedback control of individual LEDs. The output spectral irradiance or radiance of the source will be calibrated by a reference instrument, and the source will be used as a spectroradiometric as well as a photometric and colorimetric standard. A series of simulations have been conducted to predict the performance of the designed tunable source when used for calibration of display colorimeters. The results indicate that the errors can be reduced by an order of magnitude when the tunable source is used to calibrate the colorimeters, compared with measurement errors when the colorimeters are calibrated against Illuminant A. The source can also approximate various CIE daylight illuminants and common lamp spectral distributions for other photometric and colorimetric applications.

  3. NVLAP calibration laboratory program

    Energy Technology Data Exchange (ETDEWEB)

    Cigler, J.L.

    1993-12-31

    This paper presents an overview of the progress up to April 1993 in the development of the Calibration Laboratories Accreditation Program within the framework of the National Voluntary Laboratory Accreditation Program (NVLAP) at the National Institute of Standards and Technology (NIST).

  4. Calibrating Communication Competencies

    Science.gov (United States)

    Surges Tatum, Donna

    2016-11-01

    The Many-faceted Rasch measurement model is used in the creation of a diagnostic instrument by which communication competencies can be calibrated, the severity of observers/raters can be determined, the ability of speakers measured, and comparisons made between various groups.

  5. ECAL Energy Flow Calibration

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    My talk will be covering my work as a whole over the course of the semester. The focus will be on using energy flow calibration in ECAL to check the precision of the corrections made by the light monitoring system used to account for transparency loss within ECAL crystals due to radiation damage over time.

  6. Entropic calibration revisited

    Energy Technology Data Exchange (ETDEWEB)

    Brody, Dorje C. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)]. E-mail: d.brody@imperial.ac.uk; Buckley, Ian R.C. [Centre for Quantitative Finance, Imperial College, London SW7 2AZ (United Kingdom); Constantinou, Irene C. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom); Meister, Bernhard K. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

    2005-04-11

    The entropic calibration of the risk-neutral density function is effective in recovering the strike dependence of options, but encounters difficulties in determining the relevant greeks. By use of put-call reversal we apply the entropic method to the time reversed economy, which allows us to obtain the spot price dependence of options and the relevant greeks.

  7. Measurement System & Calibration report

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Villanueva, Héctor

    This Measurement System & Calibration report is describing DTU’s measurement system installed at a specific wind turbine. A part of the sensors has been installed by others, the rest of the sensors have been installed by DTU. The results of the measurements, described in this report, are only val...

  8. ATLAS Tile calorimeter calibration and monitoring systems

    CERN Document Server

    Cortes-Gonzalez, Arely; The ATLAS collaboration

    2017-01-01

    The ATLAS Tile Calorimeter is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes, located in the outer part of the calorimeter. The readout is segmented into about 5000 cells (longitudinally and transversally), each of them being read out by two photomultiplier in parallel. To calibrate and monitor the stability and performance of each part of the readout chain during the data taking, a set of calibration systems is used. The calibration system comprises Cesium radioactive sources, laser, charge injection elements and an integrator based readout system. Combined information from all systems allows to monitor and equalise the calorimeter r...

  9. ATLAS Tile calorimeter calibration and monitoring systems

    CERN Document Server

    Boumediene, Djamel Eddine; The ATLAS collaboration

    2017-01-01

    The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs). PMT signals are then digitized at 40 MHz and stored on detector and are only transferred off detector once the first level trigger acceptance has been confirmed. The readout is segmented into about 5000 cells (longitudinally and transversally), each of them being read out by two PMTs in parallel. To calibrate and monitor the stability and performance of each part of the readout chain, a set of calibration systems is used. The TileCal calibration system comprises Cesium radioactive sources, laser, charge injection elements and an integrator b...

  10. ATLAS Tile calorimeter calibration and monitoring systems

    CERN Document Server

    Chomont, Arthur Rene; The ATLAS collaboration

    2016-01-01

    The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs), located on the outside of the calorimeter. The readout is segmented into about 5000 cells (longitudinally and transversally), each of them being read out by two PMTs in parallel. To calibrate and monitor the stability and performance of each part of the readout chain during the data taking, a set of calibration systems is used. The TileCal calibration system comprises Cesium radioactive sources, laser and charge injection elements and it allows to monitor and equalize the calorimeter response at each stage of the signal production, from scin...

  11. Investigation of Workplace-like Calibration Fields via a Deuterium-Tritium (D-T) Neutron Generator.

    Science.gov (United States)

    Mozhayev, Andrey V; Piper, Roman K; Rathbone, Bruce A; McDonald, Joseph C

    2017-04-01

    Radiation survey meters and personal dosimeters are typically calibrated in reference neutron fields based on conventional radionuclide sources, such as americium-beryllium (Am-Be) or californium-252 (Cf), either unmodified or heavy-water moderated. However, these calibration neutron fields differ significantly from the workplace fields in which most of these survey meters and dosimeters are being used. Although some detectors are designed to yield an approximately dose-equivalent response over a particular neutron energy range, the response of other detectors is highly dependent upon neutron energy. This, in turn, can result in significant over- or underestimation of the intensity of neutron radiation and/or personal dose equivalent determined in the work environment. The use of simulated workplace neutron calibration fields that more closely match those present at the workplace could improve the accuracy of worker, and workplace, neutron dose assessment. This work provides an overview of the neutron fields found around nuclear power reactors and interim spent fuel storage installations based on available data. The feasibility of producing workplace-like calibration fields in an existing calibration facility has been investigated via Monte Carlo simulations. Several moderating assembly configurations, paired with a neutron generator using the deuterium tritium (D-T) fusion reaction, were explored.

  12. PV Cell and Module Calibrations at NREL

    Energy Technology Data Exchange (ETDEWEB)

    Emery, Keith

    2012-10-22

    NREL has equipment to measure any conceivable cell or module technology. The lack of standards for low concentration modules complicates matters. Spectrally adjustable simulators are critical for more than three junctions. NREL's 10-channel fiber optic simulator has shown that the light can be set for each junction within 1% of what it would be under the reference spectrum for up to a five-junction cell. Uncertainty in module simulators dominated by spatial nonuniformity for calibration labs. Manufacturers can mitigate this error by using matched reference modules instead of cells.

  13. Mercury CEM Calibration

    Energy Technology Data Exchange (ETDEWEB)

    John F. Schabron; Joseph F. Rovani; Susan S. Sorini

    2007-03-31

    The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005, requires that calibration of mercury continuous emissions monitors (CEMs) be performed with NIST-traceable standards. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The traceability protocol will be written by EPA. Traceability will be based on the actual analysis of the output of each calibration unit at several concentration levels ranging from about 2-40 ug/m{sup 3}, and this analysis will be directly traceable to analyses by NIST using isotope dilution inductively coupled plasma/mass spectrometry (ID ICP/MS) through a chain of analyses linking the calibration unit in the power plant to the NIST ID ICP/MS. Prior to this project, NIST did not provide a recommended mercury vapor pressure equation or list mercury vapor pressure in its vapor pressure database. The NIST Physical and Chemical Properties Division in Boulder, Colorado was subcontracted under this project to study the issue in detail and to recommend a mercury vapor pressure equation that the vendors of mercury vapor pressure calibration units can use to calculate the elemental mercury vapor concentration in an equilibrium chamber at a particular temperature. As part of this study, a preliminary evaluation of calibration units from five vendors was made. The work was performed by NIST in Gaithersburg, MD and Joe Rovani from WRI who traveled to NIST as a Visiting Scientist.

  14. Python essential reference

    CERN Document Server

    Beazley, David M

    2009-01-01

    Python Essential Reference is the definitive reference guide to the Python programming language — the one authoritative handbook that reliably untangles and explains both the core Python language and the most essential parts of the Python library. Designed for the professional programmer, the book is concise, to the point, and highly accessible. It also includes detailed information on the Python library and many advanced subjects that is not available in either the official Python documentation or any other single reference source. Thoroughly updated to reflect the significant new programming language features and library modules that have been introduced in Python 2.6 and Python 3, the fourth edition of Python Essential Reference is the definitive guide for programmers who need to modernize existing Python code or who are planning an eventual migration to Python 3. Programmers starting a new Python project will find detailed coverage of contemporary Python programming idioms.

  15. Carbon-cluster mass calibration at SHIPTRAP

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhuri, Ankur

    2007-12-10

    A carbon-cluster ion source has been installed and tested at SHIPTRAP, the Penning-trap mass spectrometer for mass measurements of heavy elements at GSI/Darmstadt, Germany. A precision mass determination is carried out by measuring the ion cyclotron frequency {omega}{sub c}=qB=m, where q/m is the charge-to-mass ratio of the ion and B is the magnetic field. The mass of the ion of interest is obtained from the comparison of its cyclotron frequency {omega}{sub c} with that of a well-known reference ion. Carbon clusters are the mass reference of choice since the unified atomic mass unit is defined as 1/12 of the mass of the {sup 12}C atom. Thus the masses of carbon clusters {sup 12}C{sub n}, n=1,2,3,.. are multiples of the unified atomic mass unit. Carbon-cluster ions {sup 12}C{sub n}{sup +}, 5{<=}n{<=}23, were produced by laser-induced desorption and ionization from a carbon sample. Carbon clusters of various sizes ({sup 12}C{sub 7}{sup +}, {sup 12}C{sub 9}{sup +}, {sup 12}C{sub 10}{sup +}, {sup 12}C{sub 11}{sup +}, {sup 12}C{sub 12}{sup +}, {sup 12}C{sub 15}{sup +}, {sup 12}C{sub 18}{sup +}, {sup 12}C{sub 19}{sup +}, {sup 12}C{sub 20}{sup +}) were used for an investigation of the accuracy of SHIPTRAP covering a mass range from 84 u to 240 u. To this end the clusters were used both as ions of interest and reference ions. Hence the true values of the frequency ratios are exactly known. The mass-dependent uncertainty was found to be negligible for the case of (m-m{sub ref})<100 u. However, a systematic uncertainty of 4.5 x 10{sup -8} was revealed. In addition, carbon clusters were employed for the first time as reference ions in an on-line studies of short-lived nuclei. Absolute mass measurements of the radionuclides {sup 144}Dy, {sup 146}Dy and {sup 147}Ho were performed using {sup 12}C{sub 11}{sup +} as reference ion. The results agree with measurements during the same run using {sup 85}Rb{sup +} as reference ion. The investigated radionuclides were produced in the

  16. A compact soft x-ray (0.1–1.2 keV) calibration bench for radiometric measurements using an original versatile Rowland circle grazing incidence monochromator

    Energy Technology Data Exchange (ETDEWEB)

    Hubert, S., E-mail: sebastien.hubert@cea.fr

    2017-05-21

    This paper describes an original Rowland circle grazing incidence spectrometer used as a monochromator for a soft x-ray Manson source in order to calibrate both the source and detectors over the 0.1–1.2 keV spectral range. The originality of the instrument lies on a patented vacuum manipulator which allows the simultaneous boarding of two detectors, one (reference) for measuring the monochromatic radiation and the second to be calibrated. In order to achieve this, the vacuum manipulator is able to interchange, in vacuum, one detector with the other in front of the exit slit of the monochromatizing stage. One purpose of this apparatus was to completely eliminate the intrinsic bremsstrahlung emission of the x-ray diode source and isolate each characteristic line for quantitative detector calibrations. Obtained spectral resolution (Δλ/λ<10{sup −2}) and spectral purity (>98%) fully meet this objective. Initially dimensioned to perform calibration of bulky x-ray cameras unfolded on the Laser MégaJoule Facility, other kinds of detector can be obviously calibrated using this instrument. A brief presentation of the first calibration of an x-ray CCD through its quantum efficiency (QE) measurement is included in this paper as example. Comparison with theoretical model for QE and previous measurements at higher energy are finally presented and discussed.

  17. Mercury Calibration System

    Energy Technology Data Exchange (ETDEWEB)

    John Schabron; Eric Kalberer; Joseph Rovani; Mark Sanderson; Ryan Boysen; William Schuster

    2009-03-11

    U.S. Environmental Protection Agency (EPA) Performance Specification 12 in the Clean Air Mercury Rule (CAMR) states that a mercury CEM must be calibrated with National Institute for Standards and Technology (NIST)-traceable standards. In early 2009, a NIST traceable standard for elemental mercury CEM calibration still does not exist. Despite the vacature of CAMR by a Federal appeals court in early 2008, a NIST traceable standard is still needed for whatever regulation is implemented in the future. Thermo Fisher is a major vendor providing complete integrated mercury continuous emissions monitoring (CEM) systems to the industry. WRI is participating with EPA, EPRI, NIST, and Thermo Fisher towards the development of the criteria that will be used in the traceability protocols to be issued by EPA. An initial draft of an elemental mercury calibration traceability protocol was distributed for comment to the participating research groups and vendors on a limited basis in early May 2007. In August 2007, EPA issued an interim traceability protocol for elemental mercury calibrators. Various working drafts of the new interim traceability protocols were distributed in late 2008 and early 2009 to participants in the Mercury Standards Working Committee project. The protocols include sections on qualification and certification. The qualification section describes in general terms tests that must be conducted by the calibrator vendors to demonstrate that their calibration equipment meets the minimum requirements to be established by EPA for use in CAMR monitoring. Variables to be examined include linearity, ambient temperature, back pressure, ambient pressure, line voltage, and effects of shipping. None of the procedures were described in detail in the draft interim documents; however they describe what EPA would like to eventually develop. WRI is providing the data and results to EPA for use in developing revised experimental procedures and realistic acceptance criteria based on

  18. Exploitation of secondary standard for calibration in units of Dw,1 cm and assessment of several HDR brachytherapy planning systems

    Science.gov (United States)

    Gabris, Frantisek; Zeman, Jozef; Valenta, Jiri; Selbach, Hans-Joachim

    2012-10-01

    A secondary standard of the BEV, calibrated at the PTB in terms of Dw,1 cm, was used for calibration of the well-type chamber-based measuring systems used in clinics. In addition to the calibration, we tried to employ it for assessment of treatment planning systems (TPS) used for each particular afterloader. The dose to water at 1 cm distance from the source position was calculated by the TPS, using reference data from the source producer certificate. The values were compared directly with the dose measured at the same distance from the source. The comparison has been carried out for GammaMed Plus and MicroSelectron HDR sources. Differences of secondary standard measurements and TPS calculations were lower than ±5%, which is below the achievable uncertainty of both dose measurement and dose determination by the TPS. Nevertheless, it is higher than generally accepted in the case of external beam radiotherapy. Additional direct measurements in terms of Dw,1 cm may improve the safety and reliability of patient treatment. Part of the EMRP JRP T02.J06 Project ‘Increasing Cancer Treatment Efficacy Using 3D Brachytherapy’.

  19. Hispanic Latin America, Spain and the Spanish-speaking Caribbean: A rich source of reference material for public health, epidemiology and tropical medicine

    Science.gov (United States)

    Williams, John R; Bórquez, Annick; Basáñez, María-Gloria

    2008-01-01

    There is a multiplicity of journals originating in Spain and the Spanish-speaking countries of Latin America and the Caribbean (SSLAC) in the health sciences of relevance to the fields of epidemiology and public health. While the subject matter of epidemiology in Spain shares many features with its neighbours in Western Europe, many aspects of epidemiology in Latin America are particular to that region. There are also distinctive theoretical and philosophical approaches to the study of epidemiology and public health arising from traditions such as the Latin American social medicine movement, of which there may be limited awareness. A number of online bibliographic databases are available which focus primarily on health sciences literature arising in Spain and Latin America, the most prominent being Literatura Latinoamericana en Ciencias de la Salud (LILACS) and LATINDEX. Some such as LILACS also extensively index grey literature. As well as in Spanish, interfaces are provided in English and Portuguese. Abstracts of articles may also be provided in English with an increasing number of journals beginning to publish entire articles written in English. Free full text articles are becoming accessible, one of the most comprehensive sources being the Scientific Electronic Library Online (SciELO). There is thus an extensive range of literature originating in Spain and SSLAC freely identifiable and often accessible online, and with the potential to provide useful inputs to the study of epidemiology and public health provided that any reluctance to explore these resources can be overcome. In this article we provide an introduction to such resources. PMID:19243576

  20. Advancing Absolute Calibration for JWST and Other Applications

    Science.gov (United States)

    Rieke, George; Bohlin, Ralph; Boyajian, Tabetha; Carey, Sean; Casagrande, Luca; Deustua, Susana; Gordon, Karl; Kraemer, Kathleen; Marengo, Massimo; Schlawin, Everett; Su, Kate; Sloan, Greg; Volk, Kevin

    2017-10-01

    We propose to exploit the unique optical stability of the Spitzer telescope, along with that of IRAC, to (1) transfer the accurate absolute calibration obtained with MSX on very bright stars directly to two reference stars within the dynamic range of the JWST imagers (and of other modern instrumentation); (2) establish a second accurate absolute calibration based on the absolutely calibrated spectrum of the sun, transferred onto the astronomical system via alpha Cen A; and (3) provide accurate infrared measurements for the 11 (of 15) highest priority stars with no such data but with accurate interferometrically measured diameters, allowing us to optimize determinations of effective temperatures using the infrared flux method and thus to extend the accurate absolute calibration spectrally. This program is integral to plans for an accurate absolute calibration of JWST and will also provide a valuable Spitzer legacy.

  1. An improved outdoor calibration procedure for broadband ultraviolet radiometers.

    Science.gov (United States)

    Cancillo, M L; Serrano, A; Antón, M; García, J A; Vilaplana, J M; de la Morena, B

    2005-01-01

    This article aims at improving the broadband ultraviolet radiometer's calibration methodology. For this goal, three broadband radiometers are calibrated against a spectrophotometer of reference. Three different one-step calibration models are tested: ratio, first order and second order. The latter is proposed in order to adequately reproduce the high dependence on the solar zenith angle shown by the other two models and, therefore, to improve the calibration performance at high solar elevations. The proposed new second-order model requires no additional information and, thus, keeps the operational character of the one-step methodology. The models are compared in terms of their root mean square error and the most qualified is subsequently validated by comparing its predictions with the spectrophotometer measurements within an independent validation data subset. Results show that the best calibration is achieved by the second-order model, with a mean bias error and mean absolute bias error lower than 2.2 and 6.7%, respectively.

  2. Optimized Spectrometers Characterization Procedure for Near Ground Support of ESA FLEX Observations: Part 1 Spectral Calibration and Characterisation

    Directory of Open Access Journals (Sweden)

    Laura Mihai

    2018-02-01

    Full Text Available The paper presents two procedures for the wavelength calibration, in the oxygen telluric absorption spectral bands (O2-A, λc = 687 nm and O2-B, λc = 760.6 nm, of field fixed-point spectrometers used for reflectance and Sun-induced fluorescence measurements. In the first case, Ne and Ar pen-type spectral lamps were employed, while the second approach is based on a double monochromator setup. The double monochromator system was characterized for the estimation of errors associated with different operating configurations. The proposed methods were applied to three Piccolo Doppio-type systems built around two QE Pros and one USB2 + H16355 Ocean Optics spectrometers. The wavelength calibration errors for all the calibrations performed on the three spectrometers are reported and potential methodological improvements discussed. The suggested calibration methods were validated, as the wavelength corrections obtained by both techniques for the QE Pro designed for fluorescence investigations were similar. However, it is recommended that a neon emission line source, as well as an argon or mercury-argon source be used to have a reference wavelength closer to the O2-B feature. The wavelength calibration can then be optimised as close to the O2-B and O2-A features as possible. The monochromator approach could also be used, but that instrument would need to be fully characterized prior to use, and although it may offer a more accurate calibration, as it could be tuned to emit light at the same wavelengths as the absorption features, it would be more time consuming as it is a scanning approach.

  3. UV irradiance radiometers calibration procedure

    OpenAIRE

    Doctorovich I. V.; Butenko V. K.; Hodovaniouk V. N.; Fodchuk I. M.; Yuriev V. G.

    2008-01-01

    The paper deals with the problems arising at calibration of narrow-band spectral-sensitive radiometers. The procedure of irradiance unit transfer to UV radiometers — UV radiometers calibration procedure — is presented.

  4. Monte Carlo modeling provides accurate calibration factors for radionuclide activity meters.

    Science.gov (United States)

    Zagni, F; Cicoria, G; Lucconi, G; Infantino, A; Lodi, F; Marengo, M

    2014-12-01

    Accurate determination of calibration factors for radionuclide activity meters is crucial for quantitative studies and in the optimization step of radiation protection, as these detectors are widespread in radiopharmacy and nuclear medicine facilities. In this work we developed the Monte Carlo model of a widely used activity meter, using the Geant4 simulation toolkit. More precisely the "PENELOPE" EM physics models were employed. The model was validated by means of several certified sources, traceable to primary activity standards, and other sources locally standardized with spectrometry measurements, plus other experimental tests. Great care was taken in order to accurately reproduce the geometrical details of the gas chamber and the activity sources, each of which is different in shape and enclosed in a unique container. Both relative calibration factors and ionization current obtained with simulations were compared against experimental measurements; further tests were carried out, such as the comparison of the relative response of the chamber for a source placed at different positions. The results showed a satisfactory level of accuracy in the energy range of interest, with the discrepancies lower than 4% for all the tested parameters. This shows that an accurate Monte Carlo modeling of this type of detector is feasible using the low-energy physics models embedded in Geant4. The obtained Monte Carlo model establishes a powerful tool for first instance determination of new calibration factors for non-standard radionuclides, for custom containers, when a reference source is not available. Moreover, the model provides an experimental setup for further research and optimization with regards to materials and geometrical details of the measuring setup, such as the ionization chamber itself or the containers configuration. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Lidar calibration experiments

    DEFF Research Database (Denmark)

    Ejsing Jørgensen, Hans; Mikkelsen, T.; Streicher, J.

    1997-01-01

    A series of atmospheric aerosol diffusion experiments combined with lidar detection was conducted to evaluate and calibrate an existing retrieval algorithm for aerosol backscatter lidar systems. The calibration experiments made use of two (almost) identical mini-lidar systems for aerosol cloud...... detection to test the reproducibility and uncertainty of lidars. Lidar data were obtained from both single-ended and double-ended Lidar configurations. A backstop was introduced in one of the experiments and a new method was developed where information obtained from the backstop can be used in the inversion...... algorithm. Independent in-situ aerosol plume concentrations were obtained from a simultaneous tracer gas experiment with SF6, and comparisons with the two lidars were made. The study shows that the reproducibility of the lidars is within 15%, including measurements from both sides of a plume...

  6. Accurate borehole probe calibration

    Energy Technology Data Exchange (ETDEWEB)

    Tchen, T.; Eisler, P. (CSIRO, Mount Waverley, Vic. (Australia). Division of Geomechanics)

    The In Situ Minerals Analysis Group in the CSIRO Division of Geomechanics has developed quantitative borehole logging techniques applicable to iron-ore and coal deposits. They are used currently to determine the formation density, either the iron-ore grades or the raw coal-ash contents, as appropriate, and the borehole diameter. The in-situ analyses depend on probe-calibration equations which were formulated by linear regression analysis that related the probe's spectral outputs with the required geological variable. Calibration equations consisting of a linear combination of first-order terms gave excellent assaying accuracy. The group achieved further improvements in assaying accuracy by developing a more generalised calibration model based on second-order terms and cross-product terms of the probe's spectral parameters. The logging data used for the statistical analysis were recorded in mine development boreholes at three Pilbara iron-ore mines and at a Queensland coal mine. Application of the generalised model, in place of the first-order model, resulted in a reduction of the root mean square (RMS) deviation between assays obtained in the laboratory and by logging, of about 15% relative for iron-ore grades and of about 8% relative for raw coal-ash content. The study also shows that the accuracy obtained using the conventional, non-spectrometric calibration model is inferior to that obtained by using either of the two spectrometric models, where the comparisons made are based on the same set of logging data. 8 refs., 6 figs., 3 tabs.

  7. Calibrated Properties Model

    Energy Technology Data Exchange (ETDEWEB)

    H. H. Liu

    2003-02-14

    This report has documented the methodologies and the data used for developing rock property sets for three infiltration maps. Model calibration is necessary to obtain parameter values appropriate for the scale of the process being modeled. Although some hydrogeologic property data (prior information) are available, these data cannot be directly used to predict flow and transport processes because they were measured on scales smaller than those characterizing property distributions in models used for the prediction. Since model calibrations were done directly on the scales of interest, the upscaling issue was automatically considered. On the other hand, joint use of data and the prior information in inversions can further increase the reliability of the developed parameters compared with those for the prior information. Rock parameter sets were developed for both the mountain and drift scales because of the scale-dependent behavior of fracture permeability. Note that these parameter sets, except those for faults, were determined using the 1-D simulations. Therefore, they cannot be directly used for modeling lateral flow because of perched water in the unsaturated zone (UZ) of Yucca Mountain. Further calibration may be needed for two- and three-dimensional modeling studies. As discussed above in Section 6.4, uncertainties for these calibrated properties are difficult to accurately determine, because of the inaccuracy of simplified methods for this complex problem or the extremely large computational expense of more rigorous methods. One estimate of uncertainty that may be useful to investigators using these properties is the uncertainty used for the prior information. In most cases, the inversions did not change the properties very much with respect to the prior information. The Output DTNs (including the input and output files for all runs) from this study are given in Section 9.4.

  8. Complete calibration of the autonomous hand-eye robot JANUS

    OpenAIRE

    Garcia, C.

    1998-01-01

    The current prototype of the JANUS robot consists of two arms and a neck with two mounted color cameras. Calibrating JANUS means to find the geometric relationships between each of these components and the reference coordinate system of the robot. The calibration procedure that we present in this report is completely vision-based: the relationships between each camera and the neck and between each arm and the neck are determined using visual measurements, which leads to a low-cost and automat...

  9. Gearbox Reliability Collaborative High-Speed Shaft Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Keller, J.; McNiff, B.

    2014-09-01

    Instrumentation has been added to the high-speed shaft, pinion, and tapered roller bearing pair of the Gearbox Reliability Collaborative gearbox to measure loads and temperatures. The new shaft bending moment and torque instrumentation was calibrated and the purpose of this document is to describe this calibration process and results, such that the raw shaft bending and torque signals can be converted to the proper engineering units and coordinate system reference for comparison to design loads and simulation model predictions.

  10. EUV Cross-Calibration Strategies for the GOES-R SUVI

    Science.gov (United States)

    Darnel, Jonathan; Seaton, Daniel

    2016-10-01

    The challenges of maintaining calibration for solar EUV instrumentation is well-known. The lack of standard calibration sources and the fact that most solar EUV telescopes are incapable of utilizing bright astronomical EUV sources for calibration make knowledge of instrument performance quite difficult. In the recent past, calibration rocket underflights have helped establish a calibration baseline. The EVE instrument on SDO for a time provided well-calibrated, high spectral resolution solar spectra for a broad range of the EUV, but has suffered a loss of coverage at the shorter wavelengths. NOAA's Solar UltraViolet Imager (SUVI), a solar EUV imager with similarities to SDO/AIA, will provide solar imagery over nearly an entire solar cycle. In order to maintain the scientific value of the SUVI's dataset, novel approaches to calibration are necessary. Here we demonstrate a suite of methods to cross-calibrate SUVI against other solar EUV instruments through the use of proxy solar spectra.

  11. Reference dosimetry on TomoTherapy: an addendum to the 1990 UK MV dosimetry code of practice

    Science.gov (United States)

    Thomas, S. J.; Aspradakis, M. M.; Byrne, J. P.; Chalmers, G.; Duane, S.; Rogers, J.; Thomas, R. A. S.; Tudor, G. S. J.; Twyman, N.

    2014-03-01

    The current UK code of practice for high-energy photon therapy dosimetry (Lillicrap et al 1990 Phys. Med. Biol. 35 1355-60) gives instructions for measuring absorbed dose to water under reference conditions for megavoltage photons. The reference conditions and the index used to specify beam quality require that a machine be able to set a 10 cm × 10 cm field at the point of measurement. TomoTherapy machines have a maximum collimator setting of 5 cm × 40 cm at a source to axis distance of 85 cm, making it impossible for users of these machines to follow the code. This addendum addresses the specification of reference irradiation geometries, the choice of ionization chambers and the determination of dosimetry corrections, the derivation of absorbed dose to water calibration factors and choice of appropriate chamber correction factors, for carrying out reference dosimetry measurements on TomoTherapy machines. The preferred secondary standard chamber remains the NE2611 chamber, which with its associated secondary standard electrometer, is calibrated at the NPL through the standard calibration service for MV photon beams produced on linear accelerators with conventional flattening filters. Procedures are given for the derivation of a beam quality index specific to the TomoTherapy beam that can be used in the determination of a calibration coefficient for the secondary standard chamber from its calibration certificate provided by the NPL. The recommended method of transfer from secondary standard to field instrument is in a static beam, at a depth of 5 cm, by sequential substitution or by simultaneous side by side irradiation in either a water phantom or a water-equivalent solid phantom. Guidance is given on the use of a field instrument in reference fields.

  12. A self-calibrating optomechanical force sensor with femtonewton resolution

    Energy Technology Data Exchange (ETDEWEB)

    Melcher, John, E-mail: john.melcher@nist.gov; Stirling, Julian; Pratt, Jon R.; Shaw, Gordon A. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Cervantes, Felipe Guzmán [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Joint Quantum Institute, University of Maryland, College Park, Maryland 20742 (United States)

    2014-12-08

    We report the development of an ultrasensitive optomechanical sensor designed to improve the accuracy and precision of force measurements with atomic force microscopy. The sensors reach quality factors of 4.3 × 10{sup 6} and force resolution on the femtonewton scale at room temperature. Self-calibration of the sensor is accomplished using radiation pressure to create a reference force. Self-calibration enables in situ calibration of the sensor in extreme environments, such as cryogenic ultra-high vacuum. The senor technology presents a viable route to force measurements at the atomic scale with uncertainties below the percent level.

  13. Polymers for Traveling Wave Ion Mobility Spectrometry Calibration

    Science.gov (United States)

    Duez, Quentin; Chirot, Fabien; Liénard, Romain; Josse, Thomas; Choi, ChangMin; Coulembier, Olivier; Dugourd, Philippe; Cornil, Jérôme; Gerbaux, Pascal; De Winter, Julien

    2017-07-01

    One of the main issues when using traveling wave ion mobility spectrometry (TWIMS) for the determination of collisional cross-section (CCS) concerns the need for a robust calibration procedure built from referent ions of known CCS. Here, we implement synthetic polymer ions as CCS calibrants in positive ion mode. Based on their intrinsic polydispersities, polymers offer in a single sample the opportunity to generate, upon electrospray ionization, numerous ions covering a broad mass range and a large CCS window for different charge states at a time. In addition, the key advantage of polymer ions as CCS calibrants lies in the robustness of their gas-phase structure with respect to the instrumental conditions, making them less prone to collisional-induced unfolding (CIU) than protein ions. In this paper, we present a CCS calibration procedure using sodium cationized polylactide and polyethylene glycol, PLA and PEG, as calibrants with reference CCS determined on a home-made drift tube. Our calibration procedure is further validated by testing the polymer calibration to determine CCS of numerous different ions for which CCS are reported in the literature. [Figure not available: see fulltext.

  14. Calibration and intercomparison methods of dose calibrators used in nuclear medicine facilities; Metodos de calibracao e de intercomparacao de calibradores de dose utilizados em servicos de medicina nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Alessandro Martins da

    1999-07-01

    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. Reach for Reference: Elementary-Middle School Science Reference Collections

    Science.gov (United States)

    Safford, Barbara Ripp

    2005-01-01

    This article presents a brief review of some new school science reference works. Two of the sources are traditional, while one is considered experimental. The two traditional reference works reviewed are "The American Heritage Children's Science Dictionary" for upper elementary grades, and "The American Heritage Student Science Dictionary" for…

  16. Uncertainty analysis of in-flight spectral calibration for hyperspectral imaging spectrometers

    Science.gov (United States)

    Zhao, Huijie; Geng, Ruonan; Jia, Guorui; Wang, Daming

    2017-10-01

    Hyperspectral imaging instrument performance, especially spectral response parameters, may change when the sensors work in-flight due to vibrations, temperature and pressure changes compared with the laboratory status. In order to derive valid information from imaging data, accurate spectral calibration accompanied by uncertainty analysis to the data must be made. The purpose of this work is to present a process to estimate the uncertainties of in-flight spectral calibration parameters by analyzing the sources of uncertainty and calculating their sensitivity coefficients. In the in-flight spectral calibration method, the band-center and bandwidth determinations are made by correlating the in-flight sensor measured radiance with reference radiance. In this procedure, the uncertainty analysis is conducted separately for three factors: (a) the radiance calculated from imaging data; (b) the reference data; (c) the matching process between the above two items. To obtain the final uncertainty, contributions due to every impact factor must be propagated through this process. Analyses have been made using above process for the Hyperion data. The results show that the shift of band-center in the oxygen absorption (about 762nm), compared with the value measured in the lab, is less than 0.9nm with uncertainties ranging from 0.063nm to 0.183nm related to spatial distribution along the across-track direction of the image, the change of bandwidth is less than 1nm with uncertainties ranging from 0.066nm to 0.166nm. This results verify the validity of the in-flight spectral calibration process.

  17. Planck 2013 results. V. LFI calibration

    Science.gov (United States)

    Planck Collaboration; Aghanim, N.; 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.; Bielewicz, P.; Bobin, J.; Bock, J. J.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R. C.; Cappellini, B.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chen, X.; Chiang, L.-Y.; Christensen, P. R.; Church, S.; Colombi, S.; Colombo, L. P. L.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Gaier, T. C.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Hanson, D.; Harrison, D.; 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, A. H.; Jaffe, T. R.; Jewell, J.; Jones, W. C.; Juvela, M.; Kangaslahti, P.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Leach, S.; Leahy, J. P.; Leonardi, R.; Lesgourgues, J.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Mazzotta, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Naselsky, P.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Novikov, D.; Novikov, I.; O'Dwyer, I. J.; Osborne, S.; Paci, F.; Pagano, L.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, D.; Peel, M.; Perdereau, O.; Perotto, L.; Perrotta, F.; 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.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Ricciardi, S.; Riller, T.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Scott, D.; Seiffert, M. D.; Shellard, E. P. S.; Spencer, L. D.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Türler, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Varis, J.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Watson, R.; Wilkinson, A.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-11-01

    We discuss the methods employed to photometrically calibrate the data acquired by the Low Frequency Instrument on Planck. Our calibration is based on a combination of the orbital dipole plus the solar dipole, caused respectively by the motion of the Planck spacecraft with respect to the Sun and by motion of the solar system with respect to the cosmic microwave background (CMB) rest frame. The latter provides a signal of a few mK with the same spectrum as the CMB anisotropies and is visible throughout the mission. In this data releasewe rely on the characterization of the solar dipole as measured by WMAP. We also present preliminary results (at 44 GHz only) on the study of the Orbital Dipole, which agree with the WMAP value of the solar system speed within our uncertainties. We compute the calibration constant for each radiometer roughly once per hour, in order to keep track of changes in the detectors' gain. Since non-idealities in the optical response of the beams proved to be important, we implemented a fast convolution algorithm which considers the full beam response in estimating the signal generated by the dipole. Moreover, in order to further reduce the impact of residual systematics due to sidelobes, we estimated time variations in the calibration constant of the 30 GHz radiometers (the ones with the largest sidelobes) using the signal of an internal reference load at 4 K instead of the CMB dipole. We have estimated the accuracy of the LFI calibration following two strategies: (1) we have run a set of simulations to assess the impact of statistical errors and systematic effects in the instrument and in the calibration procedure; and (2) we have performed a number of internal consistency checks on the data and on the brightness temperature of Jupiter. Errors in the calibration of this Planck/LFI data release are expected to be about 0.6% at 44 and 70 GHz, and 0.8% at 30 GHz. Both these preliminary results at low and high ℓ are consistent with WMAP results

  18. Precision Calibration of Infrared Synchrotron Radiation Detectors

    CERN Document Server

    Maltsev, A A; Maslova, M V

    2003-01-01

    The technique of calibration of synchrotron radiation precision detectors on a tungsten source based on similarity (close similarity) of character of spectral distributions of synchrotron and thermal radiations is given. The characteristics of various commonly used lamps, used as "standard" ones, are given. The errors of measurements are analyzed. The detectors are intended for absolute measurements of the number of electrons in a ring-shaped bunch.

  19. An approach to establish the uncertainty budget of catalytic activity concentration measurements in a reference laboratory.

    Science.gov (United States)

    Rami, Laura; Canalias, Francesca

    2015-04-01

    Reference laboratories providing reference services recognized by the Joint Committee for Traceability in Laboratory Medicine (JCTLM) must be accredited as calibration laboratories according to ISO 17025 and ISO 15195. These standards require laboratories to establish an uncertainty budget, in which the uncertainty contributions of the relevant uncertainty components are specified. We present a model to estimate the measurement uncertainty of creatine kinase catalytic activity concentration results obtained by IFCC primary reference measurement procedure. The measurement uncertainty has been estimated by following the next steps: 1) specification of the measurand; 2) identification of the most relevant uncertainty sources; 3) estimation of standard uncertainties by either type A or type B evaluation; 4) estimation of combined uncertainty while taking into account sensitivity coefficients, as well as existence of correlated uncertainty sources; and 5) estimation of expanded uncertainty with a defined coverage probability. The estimated expanded uncertainty was 2.2% (k=2). Uncertainty sources with a significant contribution to the measurement uncertainty were the following: pH adjustment (0.68%), absorbance accuracy (0.48%), wavelength adjustment (0.20%), reaction temperature (0.19%), volume fraction of sample (0.15%) and absorbance linearity (0.06%). The present model is an approach to establish the uncertainty budget of primary reference procedures for the measurement of the catalytic activity concentration of enzymes, and aims at being an example to be followed by other reference laboratories, as well as by laboratories that carry out primary reference measurement procedures.

  20. Absolute Antenna Calibration at the US National Geodetic Survey

    Science.gov (United States)

    Mader, G. L.; Bilich, A. L.

    2012-12-01

    Geodetic GNSS applications routinely demand millimeter precision and extremely high levels of accuracy. To achieve these accuracies, measurement and instrument biases at the centimeter to millimeter level must be understood. One of these biases is the antenna phase center, the apparent point of signal reception for a GNSS antenna. It has been well established that phase center patterns differ between antenna models and manufacturers; additional research suggests that the addition of a radome or the choice of antenna mount can significantly alter those a priori phase center patterns. For the more demanding GNSS positioning applications and especially in cases of mixed-antenna networks, it is all the more important to know antenna phase center variations as a function of both elevation and azimuth in the antenna reference frame and incorporate these models into analysis software. Determination of antenna phase center behavior is known as "antenna calibration". Since 1994, NGS has computed relative antenna calibrations for more than 350 antennas. In recent years, the geodetic community has moved to absolute calibrations - the IGS adopted absolute antenna phase center calibrations in 2006 for use in their orbit and clock products, and NGS's CORS group began using absolute antenna calibration upon the release of the new CORS coordinates in IGS08 epoch 2005.00 and NAD 83(2011,MA11,PA11) epoch 2010.00. Although NGS relative calibrations can be and have been converted to absolute, it is considered best practice to independently measure phase center characteristics in an absolute sense. Consequently, NGS has developed and operates an absolute calibration system. These absolute antenna calibrations accommodate the demand for greater accuracy and for 2-dimensional (elevation and azimuth) parameterization. NGS will continue to provide calibration values via the NGS web site www.ngs.noaa.gov/ANTCAL, and will publish calibrations in the ANTEX format as well as the legacy ANTINFO

  1. The Impact of Indoor and Outdoor Radiometer Calibration on Solar Measurements: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Habte, Aron; Sengupta, Manajit; Andreas, Afshin; Reda, Ibrahim; Robinson, Justin

    2016-07-01

    Accurate solar radiation data sets are critical to reducing the expenses associated with mitigating performance risk for solar energy conversion systems, and they help utility planners and grid system operators understand the impacts of solar resource variability. The accuracy of solar radiation measured by radiometers depends on the instrument performance specification, installation method, calibration procedure, measurement conditions, maintenance practices, location, and environmental conditions. This study addresses the effect of calibration methodologies and the resulting calibration responsivities provided by radiometric calibration service providers such as the National Renewable Energy Laboratory (NREL) and manufacturers of radiometers. Some of these radiometers are calibrated indoors, and some are calibrated outdoors. To establish or understand the differences in calibration methodology, we processed and analyzed field-measured data from these radiometers. This study investigates calibration responsivities provided by NREL's broadband outdoor radiometer calibration (BORCAL) and a few prominent manufacturers. The reference radiometer calibrations are traceable to the World Radiometric Reference. These different methods of calibration demonstrated 1% to 2% differences in solar irradiance measurement. Analyzing these values will ultimately assist in determining the uncertainties of the radiometer data and will assist in developing consensus on a standard for calibration.

  2. Calibrating ground-based microwave radiometers: Uncertainty and drifts

    Science.gov (United States)

    Küchler, N.; Turner, D. D.; Löhnert, U.; Crewell, S.

    2016-04-01

    The quality of microwave radiometer (MWR) calibrations, including both the absolute radiometric accuracy and the spectral consistency, determines the accuracy of geophysical retrievals. The Microwave Radiometer Calibration Experiment (MiRaCalE) was conducted to evaluate the performance of MWR calibration techniques, especially of the so-called Tipping Curve Calibrations (TCC) and Liquid Nitrogen Calibrations (LN2cal), by repeatedly calibrating a fourth-generation Humidity and Temperature Profiler (HATPRO-G4) that measures downwelling radiance between 20 GHz and 60 GHz. MiRaCalE revealed two major points to improve MWR calibrations: (i) the necessary repetition frequency for MWR calibration techniques to correct drifts, which ensures stable long-term measurements; and (ii) the spectral consistency of control measurements of a well known reference is useful to estimate calibration accuracy. Besides, we determined the accuracy of the HATPRO's liquid nitrogen-cooled blackbody's temperature. TCCs and LN2cals were found to agree within 0.5 K when observing the liquid nitrogen-cooled blackbody with a physical temperature of 77 K. This agreement of two different calibration techniques suggests that the brightness temperature of the LN2 cooled blackbody is accurate within at least 0.5 K, which is a significant reduction of the uncertainties that have been assumed to vary between 0.6 K and 1.5 K when calibrating the HATPRO-G4. The error propagation of both techniques was found to behave almost linearly, leading to maximum uncertainties of 0.7 K when observing a scene that is associated with a brightness temperature of 15 K.

  3. Transmission electron microscope calibration methods for critical dimension standards

    Science.gov (United States)

    Orji, Ndubuisi G.; Dixson, Ronald G.; Garcia-Gutierrez, Domingo I.; Bunday, Benjamin D.; Bishop, Michael; Cresswell, Michael W.; Allen, Richard A.; Allgair, John A.

    2016-10-01

    One of the key challenges in critical dimension (CD) metrology is finding suitable dimensional calibration standards. The transmission electron microscope (TEM), which produces lattice-resolved images having scale traceability to the SI (International System of Units) definition of length through an atomic lattice constant, has gained wide usage in different areas of CD calibration. One such area is critical dimension atomic force microscope (CD-AFM) tip width calibration. To properly calibrate CD-AFM tip widths, errors in the calibration process must be quantified. Although the use of TEM for CD-AFM tip width calibration has been around for about a decade, there is still confusion on what should be considered in the uncertainty analysis. We characterized CD-AFM tip-width samples using high-resolution TEM and high angle annular dark field scanning TEM and two CD-AFMs that are implemented as reference measurement systems. The results are used to outline how to develop a rigorous uncertainty estimate for TEM/CD-AFM calibration, and to compare how information from the two electron microscopy modes are applied to practical CD-AFM measurements. The results also represent a separate validation of previous TEM/CD-AFM calibration. Excellent agreement was observed.

  4. NUnit Pocket Reference

    CERN Document Server

    Hamilton, Bill

    2009-01-01

    The open source NUnit framework is an excellent way to test .NET code as it is written, saving hundreds of QA hours and headaches. Unfortunately, some of those hours saved can be wasted trying to master this popular but under-documented framework. Proof that good things come in small packages, the NUnit Pocket Reference is everything you need to get NUnit up and working for you. It's the only book you'll need on this popular and practical new open source framework.

  5. Reference material manufacture and certification for the AVNG

    Energy Technology Data Exchange (ETDEWEB)

    Hauck, Danielle K [Los Alamos National Laboratory; Mac Arthur, Duncan [Los Alamos National Laboratory; Thron, Jonathan L [Los Alamos National Laboratory; Livke, Alexander [VNIIEF; Kondratov, Sergey [VNIIEF; Razinkov, Sergey [VNIIEF

    2010-01-01

    Testing and demonstration of any radiation measurement system requires the use of appropriate radioactive sources. The AVNG implementation that we describe is an attribute measurement system built by RFNC - VNIIEF in Sarov, Russia. The AVNG detects neutron and gamma radiation signatures and displays the three unclassified attributes of 'plutonium presence,' 'plutonium mass > 2 kg,' and 'plutonium isotopic ratio ({sup 240}Pu to {sup 239}Pu) < 0.1.' The AVNG was tested using a number of reference material (RM) sources with masses and isotopic ratios above and below these thresholds. The AVNG was demonstrated in June 2009 using several of these sources in addition to detector calibration sources. Since the AVNG was designed to measure multi-kg plutonium sources, the RM was manufactured specifically for use with this system. In addition, the RM was used to test the thresholds in the AVNG, so the size and composition of each RM was certified prior to use. In this presentation, we will describe the various steps in the manufacture and certification of these RM sources.

  6. Geometrical calibration of X-ray imaging chains for three-dimensional reconstruction.

    Science.gov (United States)

    Rougée, A; Picard, C; Ponchut, C; Trousset, Y

    1993-01-01

    Reconstructing a three-dimensional (3D) object from a set of its two-dimensional (2D) X-ray projections requires that the source position and image plane orientation in 3D space be obtained with high accuracy. We present a method for estimating the geometrical parameters of an X-ray imaging chain, based on the minimization of the reprojection mean quadratic error measured on reference points of a calibration phantom. This error is explicitly calculated with respect to the geometrical parameters of the conic projection, and a conjugate gradient technique is used for its minimization. By comparison to the classical unconstrained method, better results were obtained in simulation with our method, specially when only a few reference points are available. This method may be adapted to different X-ray systems and may also be extended to the estimation of the geometrical parameters of the imaging chain trajectory in the case of dynamic acquisitions.

  7. Calibration and characterization of spectral imaging systems

    Science.gov (United States)

    Polder, Gerrit; van der Heijden, Gerie W.

    2001-09-01

    Spectral image sensors provide images with a large umber of contiguous spectral channels per pixel. This paper describes the calibration of spectrograph based spectral imaging systems. The relation between pixel position and measured wavelength was determined using three different wavelength calibration sources. Results indicate that for spectral calibration a source with very small peaks,such as a HgAr source, is preferred to arrow band filters. A second order polynomial model gives a better fit than a linear model for the pixel to wavelength mapping. The signal to noise ratio (SNR)is determined per wavelength. In the blue part of the spectrum,the SNR was lower than in the green and red part.This is due to a decreased quantum efficiency of the CCD,a smaller transmission coefficient of the spectrograph,as well as poor performance of the illuminant. Increasing the amount of blue light,using additional Fluorescent tube with special coating increased the SNR considerably. Furthermore, the spatial and spectral resolution of the system are determined.These can be used to choose appropriate binning factors to decrease the image size without losing information.

  8. Relative pointing offset analysis of calibration targets with repeated observations with Herschel-SPIRE Fourier-transform spectrometer

    Science.gov (United States)

    Valtchanov, Ivan; Hopwood, Rosalind; Polehampton, Edward; Benielli, Dominique; Fulton, Trevor; Imhof, Peter; Konopczyński, Tomasz; Lim, Tanya; Lu, Nanyao; Marchili, Nicola; Naylor, David; Swinyard, Bruce

    2014-07-01

    We present a method to derive the relative pointing offsets for SPIRE Fourier-Transform Spectrometer (FTS) solar system object (SSO) calibration targets, which were observed regularly throughout the Herschel mission. We construct ratios R obs( ν) of the spectra for all observations of a given source with respect to a reference. The reference observation is selected iteratively to be the one with the highest observed continuum. Assuming that any pointing offset leads to an overall shift of the continuum level, then these R obs( ν) represent the relative flux loss due to mispointing. The mispointing effects are more pronounced for a smaller beam, so we consider only the FTS short wavelength array (SSW, 958-1546 GHz) to derive a pointing correction. We obtain the relative pointing offset by comparing R obs( ν) to a grid of expected losses for a model source at different distances from the centre of the beam, under the assumption that the SSW FTS beam can be well approximated by a Gaussian. In order to avoid dependency on the point source flux conversion, which uses a particular observation of Uranus, we use extended source flux calibrated spectra to construct R obs( ν) for the SSOs. In order to account for continuum variability, due to the changing distance from the Herschel telescope, the SSO ratios are normalised by the expected model ratios for the corresponding observing epoch. We confirm the accuracy of the derived pointing offset by comparing the results with a number of control observations, where the actual pointing of Herschel is known with good precision. Using the method we derived pointing offsets for repeated observations of Uranus (including observations centred on off-axis detectors), Neptune, Ceres and NGC 7027. The results are used to validate and improve the point-source flux calibration of the FTS.

  9. Development of a low-level radon reference chamber; Entwicklung einer Low-Level-Radon-Referenzkammer

    Energy Technology Data Exchange (ETDEWEB)

    Linzmaier, Diana

    2013-01-04

    The naturally occurring, radioactive noble gas radon-222 exists worldwide in different activity concentrations in the air. During the decay of radon-222, decay products are generated which are electrically charged and attach to aerosols in the air. Together with the aerosols, the radon is inhaled and exhaled by humans. While the radon is nearly completely exhaled, ca. 20 % of the inhaled aerosols remain in the lungs in one breath cycle. Due to ionizing radiation, in a chain of events, lung cancer might occur. Consequently, radon and its decay products are according to the current findings the second leading cause of lung cancer. At the workplace and in the home measurements of radon activity concentration are performed to determine the radiation exposition of humans. All measurement devices for the determination of radon activity concentration are calibrated above 1000 Bq/m{sup 3}, even though the mean value of the present investigation in Germany shows only 50 Bq/m{sup 3}. For the calibration of measurement devices in the range below 1000 Bq/m{sup 3} over a long time period, the generation of a stable reference atmosphere is presented in this work. Due to a long term calibration (t>5 days) of the measurement devices, smaller uncertainties result for the calibration factor. For the calibration procedure, a so-called low-level radon reference chamber was set up and started operation. The generation of a stable reference atmosphere is effected by means of emanation sources which consist of a radium-226 activity standard. On the basis of {gamma}-spectrometry, the effective emanation coefficient ofthe emanation sources is determined. The traceability of the activity concentration in the reference volume is realized via the activity ofthe radium-226, the emanation coefficient and the volume. With the emanation sources produced, stable reference atmospheres within the range of 150 Bq/m{sup 3} to 1900 Bq/m{sup 3} are achieved. For the realization, maintenance and

  10. Forward Global Photometric Calibration of the Dark Energy Survey

    Science.gov (United States)

    Burke, D. L.; Rykoff, E. S.; Allam, S.; Annis, J.; Bechtol, K.; Bernstein, G. M.; Drlica-Wagner, A.; Finley, D. A.; Gruendl, R. A.; James, D. J.; Kent, S.; Kessler, R.; Kuhlmann, S.; Lasker, J.; Li, T. S.; Scolnic, D.; Smith, J.; Tucker, D. L.; Wester, W.; Yanny, B.; Abbott, T. M. C.; Abdalla, F. B.; Benoit-Lévy, A.; Bertin, E.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; D’Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; García-Bellido, J.; Gruen, D.; Gutierrez, G.; Honscheid, K.; Kuehn, K.; Kuropatkin, N.; Maia, M. A. G.; March, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Miquel, R.; Plazas, A. A.; Sako, M.; Sanchez, E.; Scarpine, V.; Schindler, R.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Walker, A. R.; DES Collaboration

    2018-01-01

    Many scientific goals for the Dark Energy Survey (DES) require the calibration of optical/NIR broadband b = grizY photometry that is stable in time and uniform over the celestial sky to one percent or better. It is also necessary to limit to similar accuracy systematic uncertainty in the calibrated broadband magnitudes due to uncertainty in the spectrum of the source. Here we present a “Forward Global Calibration Method (FGCM)” for photometric calibration of the DES, and we present results of its application to the first three years of the survey (Y3A1). The FGCM combines data taken with auxiliary instrumentation at the observatory with data from the broadband survey imaging itself and models of the instrument and atmosphere to estimate the spatial and time dependences of the passbands of individual DES survey exposures. “Standard” passbands that are typical of the passbands encountered during the survey are chosen. The passband of any individual observation is combined with an estimate of the source spectral shape to yield a magnitude {m}b{std} in the standard system. This “chromatic correction” to the standard system is necessary to achieve subpercent calibrations and in particular, to resolve ambiguity between the broadband brightness of a source and the shape of its SED. The FGCM achieves a reproducible and stable photometric calibration of standard magnitudes {m}b{std} of stellar sources over the multiyear Y3A1 data sample with residual random calibration errors of σ =6{--}7 {mmag} per exposure. The accuracy of the calibration is uniform across the 5000 {\\deg }2 DES footprint to within σ =7 {mmag}. The systematic uncertainties of magnitudes in the standard system due to the spectra of sources are less than 5 {mmag} for main-sequence stars with 0.5< g-i< 3.0.

  11. CALIBRATED HYDRODYNAMIC MODEL

    Directory of Open Access Journals (Sweden)

    Sezar Gülbaz

    2015-01-01

    Full Text Available The land development and increase in urbanization in a watershed affect water quantityand water quality. On one hand, urbanization provokes the adjustment of geomorphicstructure of the streams, ultimately raises peak flow rate which causes flood; on theother hand, it diminishes water quality which results in an increase in Total SuspendedSolid (TSS. Consequently, sediment accumulation in downstream of urban areas isobserved which is not preferred for longer life of dams. In order to overcome thesediment accumulation problem in dams, the amount of TSS in streams and inwatersheds should be taken under control. Low Impact Development (LID is a BestManagement Practice (BMP which may be used for this purpose. It is a land planningand engineering design method which is applied in managing storm water runoff inorder to reduce flooding as well as simultaneously improve water quality. LID includestechniques to predict suspended solid loads in surface runoff generated over imperviousurban surfaces. In this study, the impact of LID-BMPs on surface runoff and TSS isinvestigated by employing a calibrated hydrodynamic model for Sazlidere Watershedwhich is located in Istanbul, Turkey. For this purpose, a calibrated hydrodynamicmodel was developed by using Environmental Protection Agency Storm WaterManagement Model (EPA SWMM. For model calibration and validation, we set up arain gauge and a flow meter into the field and obtain rainfall and flow rate data. Andthen, we select several LID types such as retention basins, vegetative swales andpermeable pavement and we obtain their influence on peak flow rate and pollutantbuildup and washoff for TSS. Consequently, we observe the possible effects ofLID on surface runoff and TSS in Sazlidere Watershed.

  12. Design and calibration of field deployable ground-viewing radiometers.

    Science.gov (United States)

    Anderson, Nikolaus; Czapla-Myers, Jeffrey; Leisso, Nathan; Biggar, Stuart; Burkhart, Charles; Kingston, Rob; Thome, Kurtis

    2013-01-10

    Three improved ground-viewing radiometers were built to support the Radiometric Calibration Test Site (RadCaTS) developed by the Remote Sensing Group (RSG) at the University of Arizona. Improved over previous light-emitting diode based versions, these filter-based radiometers employ seven silicon detectors and one InGaAs detector covering a wavelength range of 400-1550 nm. They are temperature controlled and designed for greater stability and lower noise. The radiometer systems show signal-to-noise ratios of greater than 1000 for all eight channels at typical field calibration signal levels. Predeployment laboratory radiance calibrations using a 1 m spherical integrating source compare well with in situ field calibrations using the solar radiation based calibration method; all bands are within ±2.7% for the case tested.

  13. Smart Calibration of Excavators

    DEFF Research Database (Denmark)

    Bro, Marie; Døring, Kasper; Ellekilde, Lars-Peter

    2005-01-01

    Excavators dig holes. But where is the bucket? The purpose of this report is to treat four different problems concerning calibrations of position indicators for excavators in operation at concrete construction sites. All four problems are related to the question of how to determine the precise...... geographic and/or site-relative position of a given excavator and its bucket. However, our presentations and solutions to the problems can, nevertheless, be read and studied in any order and independently of each other. This also implies and induces a gentle warning to the reader: The {\\em{notation}} need...

  14. Local Hadronic Calibration

    CERN Document Server

    Barillari, T; Carli, T; Erdmann, J; Giovannini, P; Grahn, K J; Issever, C; Jantsch, A; Kiryunin, A; Lohwasser, K; Maslennikov, A; Menke, S; Oberlack, H; Pospelov, G; Rauter, E; Schacht, P; Spanó, F; Speckmayer, P; Stavina, P; Strízenec, P

    2008-01-01

    The scheme of the hadronic calibration is discussed. Based on the cluster reconstruction an effective noise suppression is achieved. In a first step clusters are classified as electromagnetic or hadronic clusters. The weighting scheme to correct for the different e/pion response in the ATLAS calorimeter is presented. Dead material corrections and out of cluster corrections yield finally a signal which is rather close to the energy deposited by the final state particles in the ATLAS calorimeter. The constants and algorithms are derived from single pion MC studies and tested with jets. The validation of the scheme using testbeam data is presented as well.

  15. ALTEA: The instrument calibration

    Energy Technology Data Exchange (ETDEWEB)

    Zaconte, V. [INFN and University of Rome Tor Vergata, Department of Physics, Via della Ricerca Scientifica 1, 00133 Rome (Italy)], E-mail: livio.narici@roma2.infn.it; Belli, F.; Bidoli, V.; Casolino, M.; Di Fino, L.; Narici, L.; Picozza, P.; Rinaldi, A. [INFN and University of Rome Tor Vergata, Department of Physics, Via della Ricerca Scientifica 1, 00133 Rome (Italy); Sannita, W.G. [DISM, University of Genova, Genova (Italy); Department of Psychiatry, SUNY, Stoony Brook, NY (United States); Finetti, N.; Nurzia, G.; Rantucci, E.; Scrimaglio, R.; Segreto, E. [Department of Physics, University and INFN, L' Aquila (Italy); Schardt, D. [GSI/Biophysik, Darmstadt (Germany)

    2008-05-15

    The ALTEA program is an international and multi-disciplinary project aimed at studying particle radiation in space environment and its effects on astronauts' brain functions, as the anomalous perception of light flashes first reported during Apollo missions. The ALTEA space facility includes a 6-silicon telescopes particle detector, and is onboard the International Space Station (ISS) since July 2006. In this paper, the detector calibration at the heavy-ion synchrotron SIS18 at GSI Darmstadt will be presented and compared to the Geant 3 Monte Carlo simulation. Finally, the results of a neural network analysis that was used for ion discrimination on fragmentation data will also be presented.

  16. Stable Targets for Spaceborne Microwave Radiometer Calibration

    Science.gov (United States)

    Njoku, Eni G.; Chan, S. K.; Armstrong, R. L.; Brodzik, M. J.; Savoie, M. H.; Knowles, K.

    2006-01-01

    Beginning in the 1970s, continuous observations of the Earth have been made by spaceborne microwave radiometers. Since these instruments have different observational characteristics, care must be taken in combining their data to form consistent long term records of brightness temperatures and derived geophysical quantities. To be useful for climate studies, data from different instruments must be calibrated relative to each other and to reference targets on the ground whose characteristics are stable and can be monitored continuously. Identifying such targets over land is not straightforward due to the heterogeneity and complexity of the land surface and cover. In this work, we provide an analysis of multi-sensor brightness temperature statistics over ocean, tropical forest, and ice sheet locations, spanning the period from 1978 to the present, and indicate the potential of these sites as continuous calibration monitoring targets.

  17. CVD calibration light systems specifications. Rev. 0

    Energy Technology Data Exchange (ETDEWEB)

    Mcllwain, A. K. [Analytical Science Branch, Whiteshell Laboratories, AECL Research Pinawa, Manitoba (Canada)

    1992-04-15

    Two prototype Cerenkov Viewing Device Calibration Light systems for the Mark IV CVD have been fabricated. They consist of a maintenance unit that will be used by the IAEA maintenance staff and a field unit that will be used by IAEA inspectors. More detailed information on the design of the calibration units can be obtained from the document SSP-39 and additional information on the Mark IV CVD can be obtained from the operating manual published as Canadian Safeguards Support Program document CSSP 6. The specifications refer to the prototype units which will be demonstrated to the IAEA in 1992 May. Based upon the feedback from the IAEA, the instruments will be changed in the final production models to provide devices that more closely satisfy the needs of the end users.

  18. Recent Goddard Space Flight Center (GSFC) experience with on-orbit calibration of attitude sensors

    Science.gov (United States)

    Davis, W.; Hashmall, J.; Harman, R.

    1992-01-01

    The results of on-orbit calibration for several satellites by the flight Dynamics Facility (FDF) at GSFC are reviewed. The examples discussed include attitude calibrations for sensors, including fixed-head star trackers, fine sun sensors, three-axis magnetometers, and inertial reference units taken from recent experience with the Compton Gamma Ray observatory, the Upper Atmosphere Research Satellite, and the Extreme Ultraviolet Explorer calibration. The methods used and the results of calibration are discussed, as are the improvements attained from in-flight calibration.

  19. Modernization of Koesters interferometer and high accuracy calibration gauge blocks

    Science.gov (United States)

    França, R. S.; Silva, I. L. M.; Couceiro, I. B.; Torres, M. A. C.; Bessa, M. S.; Costa, P. A.; Oliveira, W., Jr.; Grieneisen, H. P. H.

    2016-07-01

    The Optical Metrology Division (Diopt) of Inmetro is responsible for maintaining the national reference of the length unit according to International System of Units (SI) definitions. The length unit is realized by interferometric techniques and is disseminated to the dimensional community through calibrations of gauge blocks. Calibration of large gauge blocks from 100 mm to 1000 mm has been performed by Diopt with a Koesters interferometer with reference to spectral lines of a krypton discharge lamp. Replacement of this lamp by frequency stabilized lasers, traceable now to the time and frequency scale, is described and the first results are reported.

  20. Node-to-node field calibration of wireless distributed air pollution sensor network.

    Science.gov (United States)

    Kizel, Fadi; Etzion, Yael; Shafran-Nathan, Rakefet; Levy, Ilan; Fishbain, Barak; Bartonova, Alena; Broday, David M

    2018-02-01

    Low-cost air quality sensors offer high-resolution spatiotemporal measurements that can be used for air resources management and exposure estimation. Yet, such sensors require frequent calibration to provide reliable data, since even after a laboratory calibration they might not report correct values when they are deployed in the field, due to interference with other pollutants, as a result of sensitivity to environmental conditions and due to sensor aging and drift. Field calibration has been suggested as a means for overcoming these limitations, with the common strategy involving periodical collocations of the sensors at an air quality monitoring station. However, the cost and complexity involved in relocating numerous sensor nodes back and forth, and the loss of data during the repeated calibration periods make this strategy inefficient. This work examines an alternative approach, a node-to-node (N2N) calibration, where only one sensor in each chain is directly calibrated against the reference measurements and the rest of the sensors are calibrated sequentially one against the other while they are deployed and collocated in pairs. The calibration can be performed multiple times as a routine procedure. This procedure minimizes the total number of sensor relocations, and enables calibration while simultaneously collecting data at the deployment sites. We studied N2N chain calibration and the propagation of the calibration error analytically, computationally and experimentally. The in-situ N2N calibration is shown to be generic and applicable for different pollutants, sensing technologies, sensor platforms, chain lengths, and sensor order within the chain. In particular, we show that chain calibration of three nodes, each calibrated for a week, propagate calibration errors that are similar to those found in direct field calibration. Hence, N2N calibration is shown to be suitable for calibration of distributed sensor networks. Copyright © 2017 Elsevier Ltd. All